Allsop, DJ, Norberg, MM, Copeland, J, Fu, S & Budney, AJ 2011, 'The Cannabis Withdrawal Scale development: Patterns and predictors of cannabis withdrawal and distress', DRUG AND ALCOHOL DEPENDENCE, vol. 119, no. 1-2, pp. 123-129.
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Background Rates of treatment seeking for cannabis are increasing, and relapse is common. Management of cannabis withdrawal is an important intervention point. No psychometrically sound measure for cannabis withdrawal exists, and as a result treatment developments cannot be optimally targeted. The aim is to develop and test the psychometrics of the Cannabis Withdrawal Scale and use it to explore predictors of cannabis withdrawal. Methods A volunteer sample of 49 dependent cannabis users provided daily scores on the Cannabis Withdrawal Scale during a baseline week and 2 weeks of abstinence. Results Internal reliability (Cronbach's alpha = 0.91), testretest stability (average intra-class correlation = 0.95) and content validity analysis show that the Cannabis Withdrawal Scale has excellent psychometric properties. Nightmares and/or strange dreams was the most valid item (Wald ?2 = 105.6, P < 0.0001), but caused relatively little associated distress (Wald ?2 = 25.11, P = 0.03). Angry outbursts were considered intense (Wald ?2 = 73.69, P < 0.0001) and caused much associated distress (Wald ?2 = 45.54, P < 0.0001). Trouble getting to sleep was also an intense withdrawal symptom (Wald ?2 = 42.31, P < 0.0001) and caused significant associated distress (Wald ?2 = 47.76, P < 0.0001). Scores on the Severity of Dependence Scale predicted cannabis withdrawal. Conclusions The Cannabis Withdrawal Scale can be used as a diagnostic instrument in clinical and research settings where regular monitoring of withdrawal symptoms is required.
Alomari, MM & Zhu, JG 2011, 'Bifurcation control of subsynchronous resonance using TCSC', Communications in Nonlinear Science and Numerical Simulation, vol. 16, no. 5, pp. 2363-2370.
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This paper presents the use of Thyristor-Controlled Series Capacitor (TCSC) to control bifurcations of subsynchronous resonance (SSR) in multimachine power system. The modified second system of the IEEE second benchmark model of subsynchronous resonance is considered. The dynamics of the damper windings, automatic voltage regulator (AVR), and power system stabilizer (PSS) on SSR in power system are included. In the case of neglecting TCSC, the results show that the operating point of the system loses stability via subcritical Hopf bifurcation. When we add TCSC to the system, all bifurcations are eliminated. Therefore, the Thyristor-Controlled compensated system never loses stability at any realistic firing angle. © 2010 Elsevier B.V.
Austin, C, Fryer, F, Lear, J, Bishop, D, Hare, D, Rawling, T, Kirkup, L, McDonagh, A & Doble, P 2011, 'Factors affecting internal standard selection for quantitative elemental bio-imaging of soft tissues by LA-ICP-MS', JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, vol. 26, no. 7, pp. 1494-1501.
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Element response variations under different laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) operating conditions were investigated to identify important factors for selecting an internal standard (IS) for quantitative elemental bio-imaging. Analytes covering a range of atomic masses and first ionisation potentials (FIP) were selected to investigate the signal response variation with changes in laser spot diameter, mass bias and cell sampling position. In all cases, an IS improved experimental precision regardless of a close match in element mass or FIP but optimal analyte/IS combinations depended on the difference in masses of the analyte and IS. Particular attention was paid to 13C as this isotope is typically used as an IS in elemental bio-imaging applications. Despite its non-ideal IS characteristics (often different mass and FIP to many analytes), possibility of abundance sensitivity effects and poor signal-to-background ratio, 13C was a suitable IS candidate exhibiting a linear response with respect to the mass ablated, apparent independence from the high abundance of the adjacent 14N mass peak and effective analyte normalisation after background subtraction as long as the 13C signal from the sample was at least 6% of the gross signal. © 2011 The Royal Society of Chemistry.
Bhatia, V, Thorogood, G, Dowd, A & Cortie, MB 2011, 'Thin Films of AuCuAl Shape Memory Alloy for Use in Plasmonic Nano-actuators', MRS Proceedings, vol. 1295, pp. 1-6.
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ABSTRACTWe describe the fabrication and structure of nanoscale thin films of β phase shape memory alloys with the nominal atomic stoichiometry Au7Cu5Al4 (corresponding to 5.8 wt% Al). These alloys possess properties that suggest they could be used in nanoscale actuators. The films described here are between 20 and 50 nm thick which is below the thickness at which some other shape memory alloys cease to transform. However, microstructural and X-ray studies confirm that the coatings still exhibit the displacive transformations that are a prerequisite for the shape memory effect.
Bhatia, VK, Kealley, CS, Prior, MJ & Cortie, MB 2011, 'Martensite destabilization in Au7Cu5Al4 shape-memory alloy', ACTA MATERIALIA, vol. 59, no. 5, pp. 2193-2200.
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Aging-induced changes in the austenite peak (A(P)) temperature of Au(7)Cu(5)Al(4) shape-memory alloy are investigated. Whereas heat treating the parent phase at temperatures >140 degrees C or aging the martensite for long times at room temperature both s
Bhosale, SV, Jani, CH, Lalander, CH, Langford, SJ, Nerush, I, Shapter, JG, Villamaina, D & Vauthey, E 2011, 'Supramolecular construction of vesicles based on core-substituted naphthalene diimide appended with triethyleneglycol motifs', Chemical Communications, vol. 47, no. 29, pp. 8226-8226.
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Bhosale, SV, Kalyankar, MB, Bhosale, SV, Patil, SG, Lalander, CH, Langford, SJ & Nalage, SV 2011, 'RETRACTED ARTICLE Supramolecular self-assembly of protoporphyrin IX amphiphiles into worm-like and particular aggregates', Supramolecular Chemistry, vol. 23, no. 3-4, pp. 263-268.
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Bhosale, SV, Kalyankar, MB, Nalage, SV, Bhosale, SV, Lalander, CH & Langford, SJ 2011, 'Supramolecular self-assembled nanowires by the aggregation of a protoporphyrin derivative in low-polarity solvents', Supramolecular Chemistry, vol. 23, no. 8, pp. 563-569.
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Bossers, LCAM, Roux, C, Bell, M & McDonagh, AM 2011, 'Methods for the enhancement of fingermarks in blood', Forensic Science International, vol. 210, no. 1-3, pp. 1-11.
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Fingermarks formed in or by blood often require specific development techniques. This review examines techniques and materials that may be used to enhance and record fingermarks deposited in blood or fingermarks generated by blood-contaminated papillary ridges. A large number of techniques are presented here and are discussed from a chemical as well as practical perspective. It is concluded that an optimized sequence of techniques targeting both latent (non-bloody) and bloody fingermarks must be applied to detect and enhance the maximum number of marks, and therefore optimize the information content from exhibits that may bear marks in blood. © 2011 Elsevier Ireland Ltd.
Buckland, D, Bhosale, SV & Langford, SJ 2011, 'A chemodosimer based on a core-substituted naphthalene diimide for fluoride ion detection', Tetrahedron Letters, vol. 52, no. 16, pp. 1990-1992.
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Callsen, G, Reparaz, JS, Wagner, MR, Kirste, R, Nenstiel, C, Hoffmann, A & Phillips, MR 2011, 'Phonon deformation potentials in wurtzite GaN and ZnO determined by uniaxial pressure dependent Raman measurements', APPLIED PHYSICS LETTERS, vol. 98, no. 6, pp. 1-3.
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We report the phonon deformation potentials of wurtzite GaN and ZnO for all zone center optical phonon modes determined by Raman measurements as a function of uniaxial pressure. Despite all the structural and optical similarities between these two material systems, the pressure dependency of their vibrational spectra exhibits fundamental distinctions, which is attributed to their different bond ionicities. In addition, the LO-TO splitting of the A1 and E1 phonon modes is analyzed which yields insight into the uniaxial pressure dependency of Born's transverse effective charge e T*. © 2011 American Institute of Physics.
Callsen, G, Reparaz, JS, Wagner, MR, Vierck, A, Phillips, MR, Thomsen, C & Hoffmann, A 2011, 'Titanium-assisted growth of silica nanowires: from surface-matched to free-standing morphologies', NANOTECHNOLOGY, vol. 22, no. 40, pp. 1-6.
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We report on an oxide-assisted growth technique for silica nanowires which allows tuning the growth from surface-matched nanowires to free-standing morphologies based on growth control by Ti in the role of a catalyst and surfactant. Using an adjustable Ti concentration, we grew silica nanowires with lengths ranging from 100nm up to several millimetres whose defect chemistry was analysed by electron microscopy tools, monochromatic cathodoluminescence imaging and time resolved photoluminescence spectroscopy. The knowledge of the luminescence properties and the related defect occurrence along with their spatial distribution is pivotal for advancing silica nanowire growth in order to realize successful device designs based on self-assembled Si/SiOx nanostructures. We demonstrate a core-shell structure of the grown nanowires with a highly luminescent 150nm thick shell and outstandingly fast decaying dynamics (≈1ns) for glass-like materials. The conjunction of the observed efficient and stable luminescences with their attributed decaying behaviours suggests applications for silica nanowires such as active and passive optical interconnectors and white light phosphors. The identification of a time domain difference for the spectral regime from 2.3 to 3.3eV, within the confined spatial dimensions of a single nanowire, is very promising for future, e.g.data transmission applications, employing silica nanowires which exhibit achievable compatibility with commonly applied silicon-based electronics. A qualitative growth model based on silica particle diffusion and Ti-assisted seed formation is developed for the various types of segregated silica nanowires which extends commonly assumed oxide-assisted growth mechanisms. © IOP Publishing Ltd.
Chen, JS, Liu, H, Qiao, SZ & Lou, XWD 2011, 'Carbon-supported ultra-thin anatase TiO2 nanosheets for fast reversible lithium storage', JOURNAL OF MATERIALS CHEMISTRY, vol. 21, no. 15, pp. 5687-5692.
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This work reports a two-step method to synthesize carbon-supported ultrathin anatase TiO2 nanosheets (C-TiO2 NSs). Three samples with distinct structures were prepared via the assembly of these unique C-TiO2 NSs, including solid TiO2 hierarchical spheres and their hollow counterparts, as well as randomly-oriented C-TiO2 NSs. Specifically, the organic additive (diethylenetriamine) serves as both the capping agent during the initial solvothermal synthesis that stabilizes the (001) facets of anatase TiO2 and also the carbon source during the subsequent carbonization process. When evaluated for electrochemical lithium storage, all three samples assembled from carbon-supported anatase TiO2 NSs exhibit high reversible capacities with superior cyclic capacity retention at a high current rate. This enhanced lithium storage performance could be attributed to the ultrathin NS structure allowing efficient Li+ ion diffusion, as well as the effective nanocarbon support granting better structural stability. These findings suggest that carbon-supported TiO2 NSs may be used as a promising anode material for high-power lithium-ion batteries.
Chen, PP-T, Downes, JE, Fernandes, AJ, Butcher, KSA, Wintrebert-Fouquet, M, Wuhrer, R & Phillips, MR 2011, 'Effects of crystallinity and chemical variation on apparent band-gap shift in polycrystalline indium nitride', THIN SOLID FILMS, vol. 519, no. 6, pp. 1831-1836.
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The nature of the apparent band-gap shift in polycrystalline indium nitride thin-films, grown by remote-plasma-enhanced chemical vapour deposition at 535 ± 10 °C, has been investigated separately in relation to growth temperature dependent crystallinity and chemical variation. Substrates of sapphire and gallium nitride on sapphire were used to study the effect of a stress-reduced template on indium nitride crystallite quality and apparent band-gap. To mimic surface growth temperature variations two glass substrates of differing thickness and thermal conductivity were intentionally used for the same growth conditions. The samples were characterised using optical transmission, scanning electron microscope, X-ray diffraction, and high-resolution X-ray photoelectron spectroscopy. The results indicate that the apparent band-gap shift in polycrystalline narrow band-gap indium nitride thin-films is not primarily determined by the quality of indium nitride crystallites but rather it is associated with growth temperature dependent chemical variations in the films. © 2010 Elsevier B.V. All rights reserved.
Cortie, MB & McDonagh, AM 2011, 'Synthesis and Optical Properties of Hybrid and Alloy Plasmonic Nanoparticles', CHEMICAL REVIEWS, vol. 111, no. 6, pp. 3713-3735.
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Synthesis and optical properties of hybrid and alloy plasmonic nanoparticles hybrid systems that display a plasmon resonance in the visible or near-visible regions of the spectrum are studied. In the hybrid system, also called passive metallo-dielectric hybrids, the functionalities of the parts remain reasonably independent. The optical properties of these structures are explained by the properties of the individual parts, except for some bathochromic shifting of the plasmon resonance of the metallic component due to the increase in local dielectric constant due to the other component. Metal-metal hybrids and their closely related alloyed nanoparticles exhibit more complex behavior. The plasmon resonance or resonances of the parts can be enhanced, shifted, or suppressed. In the case of core-shell particles, the dielectric properties of the shell material will dominate above some modest thickness, and in the limit, the result is as if the hybrid was composed throughout of the shell material.
Cortie, MB, Kealley, CS, Bhatia, V, Thorogood, GJ, Elcombe, MM & Avdeev, M 2011, 'High temperature transformations of the Au7Cu5Al4 shape-memory alloy', JOURNAL OF ALLOYS AND COMPOUNDS, vol. 509, no. 8, pp. 3502-3508.
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The beta-phase of Au(7)Cu(5)Al(4) undergoes a reversible shape-memory phase transformation, however there has been some uncertainty regarding the crystal structure or structures of the parent phase. Here we show that, under equilibrium conditions, the pa
Cortie, MB, Xiao, L, Erdei, L, Kealley, CS, Dowd, AR, Kimpton, JA & McDonagh, AM 2011, 'Thermal Stability of (KxNayH1-x-y)2Ti6O13 Nanofibers', EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, vol. 2011, no. 33, pp. 5087-5095.
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Potassium-rich titanate nanofibers were produced by digesting TiO2 in concentrated KOH solutions under hydrothermal conditions. The nanofibers were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and thermogravimetric analysis. A hexatitanate structure was assigned, in contrast to the trititanate structure usually resulting from NaOH treatment of TiO2. The potassium cations could be exchanged with others, such as sodium, hydrogen, and ammonium. The potassium-rich hexatitanate was found to be photocatalytic in its as-synthesized condition. The thermal stability of the fibers during calcination was followed in situ using X-ray diffraction and was found to be strongly dependent on the chemical composition. The potassium-rich titanate converted to anatase at only 480 °C, whereas the hydrogen- and ammonium-rich materials had to be heated to over 600 °C before conversion took place. Conversion was notably slowest in the ammonium-rich material. Surprisingly, the sodium-rich hexatitanate did not form anatase at temperatures up to 800 °C and instead recrystallized.
Davis, J, Short, K, Wuhrer, R, Phillips, M & Whittle, K 2011, 'Plasma Immersion Ion Implantation of Stainless Steel 316', Microscopy and Microanalysis, vol. 17, no. S2, pp. 1886-1887.
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Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.
Fu, S, Molnar, A, Bowron, P, Lewis, J & Wang, H 2011, 'Reduction of temazepam to diazepam and lorazepam to delorazepam during enzymatic hydrolysis', ANALYTICAL AND BIOANALYTICAL CHEMISTRY, vol. 400, no. 1, pp. 153-164.
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It has been previously reported that treatment of urinary oxazepam by commercial β-glucuronidase enzyme preparations, from Escherichia coli, Helix pomatia and Patella vulgata, results in production of nordiazepam (desmethyldiazepam) artefact. In this study, we report that this unusual reductive transformation also occurs in other benzodiazepines with a hydroxyl group at the C3 position such as temazepam and lorazepam. As determined by liquid chromatography-mass spectrometry analysis, all three enzyme preparations were found capable of converting urinary temazepam into diazepam following enzymatic incubation and subsequent liquid-liquid extraction procedures. For example, when H. pomatia enzymes were used with incubation conditions of 18 h and 50 °C, the percentage conversion, although small, was significant-approximately 1% (0.59-1.54%) in both patient and spiked blank urines. Similarly, using H. pomatia enzyme under these incubation conditions, a reductive transformation of urinary lorazepam into delorazepam (chlordesmethyldiazepam) occurred. These findings have both clinical and forensic implications. Detection of diazepam or delorazepam in biological samples following enzyme treatment should be interpreted with care. © 2011 Springer-Verlag.
Huang, Y, Dong, J, Jin, L, Zhu, J & Guo, Y 2011, 'Eddy-Current Loss Prediction in the Rotor Magnets of a Permanent Magnet Synchronous Generator With Modular Winding Feeding a Rectifier Load', IEEE Transactions on Magnetics, vol. 47, no. 10, pp. 4203-4206.
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In a permanent magnet synchronous generator (PMSG) with modular winding, significant eddy current may be induced in the rotor magnets due to asynchronous rotating stator magneto-motive forces (MMFs), and a rectifier load may signify the situation further. The eddy-current loss prediction in the rotor magnets of a PMSG with modular winding feeding a rectifier load is described. An analytical method considering the stator current harmonics and stator MMF spatial harmonics and a time-stepping, coupled-circuit, 2-D finite-element method (FEM) are adopted. The predicted losses obtained from these two methods are compared and investigated.
Huang, Z, Chen, X, Yisgedu, T, Meyers, EA, Shore, SG & Zhao, J-C 2011, 'Ammonium Octahydrotriborate (NH4B3H8): New Synthesis, Structure, and Hydrolytic Hydrogen Release', Inorganic Chemistry, vol. 50, no. 8, pp. 3738-3742.
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Huang, Z, Chen, X, Yisgedu, T, Zhao, J-C & Shore, SG 2011, 'High-capacity hydrogen release through hydrolysis of NaB3H8', International Journal of Hydrogen Energy, vol. 36, no. 12, pp. 7038-7042.
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Iacopi, F, Choi, JH, Terashima, K, Rice, PM & Dubois, G 2011, 'Cryogenic plasmas for controlled processing of nanoporous materials', Physical Chemistry Chemical Physics, vol. 13, no. 9, pp. 3634-3634.
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Jaggi, M, Schmid, B, Liu, S-X, Bhosale, SV, Rivadehi, S, Langford, SJ & Decurtins, S 2011, 'A tetrathiafulvalene-functionalized naphthalene diimide: synthesis, electrochemical and photophysical properties', Tetrahedron, vol. 67, no. 38, pp. 7231-7235.
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Jayasree, RS, Sheshanath, VB, Sumy, VK, McNaughton, D & Langford, SJ 2011, 'Photodynamic effect of novel octaphosphante porphyrin evaluated by Raman spectroscopy and fluorescence microscopy', Photodiagnosis and Photodynamic Therapy, vol. 8, no. 2, pp. 192-192.
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Jin, J, Zheng, L, Guo, Y, Xu, W & Zhu, J 2011, 'Analysis and experimental validation of an HTS linear synchronous propulsion prototype with HTS magnetic suspension', Physica C: Superconductivity, vol. 471, no. 17-18, pp. 520-527.
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A high temperature superconducting (HTS) linear propulsion system composed of a single-sided HTS linear synchronous motor (HTSLSM) in its middle and HTS magnetic suspension sub-systems on both sides has been developed. The HTSLSM uses an HTS bulk magnet array on the moving secondary, and the fieldtrapped characteristics of the HTS bulk using different magnetized methods have been measured and compared to identify their magnetization capability. In order to generate a large levitation force for the system, three different types of permanent magnet guideways (PMGs) have been numerically analyzed and experimentally verified to obtain an optimal PMG. Based on comprehensive experimental prototype tests, the results show that the HTS linear propulsion system can run with stable magnetic suspension having a constant air-gap length, and the thrust characteristics versus the exciting current, working frequency and the air-gap length have also been obtained. This work forms the basis for developing a practical HTS linear propulsion system by using HTS bulks both for propulsion and suspension.
Jin, J, Zheng, L, Xu, W, Guo, Y & Zhu, J 2011, 'Influence of external traveling-wave magnetic field on trapped field of a high temperature superconducting bulk magnet used in a linear synchronous motor', Journal of Applied Physics, vol. 109, no. 11, pp. 113913-113913.
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A single-sided high temperature superconducting (HTS) linear synchronous motor (HTSLSM) has been developed with a pulse magnetization system to obtain the HTS bulk magnet array with alternating magnetic poles for the motor secondary. In order to identify the trapped field characteristics of the HTS bulk magnet exposed to the external traveling-wave magnetic field generated by the primary of the HTSLSM, a measurement system has been built up and the relevant experiments have been carried out. The relationships between the trapped field attenuation of the HTS bulk magnet and the amplitude, frequency and acting direction of the external traveling-wave magnetic field are experimentally obtained to allow the HTSLSM characteristics to be practically verified.
Jin, J, Zheng, L, Xu, W, Guo, Y & Zhu, J 2011, 'Thrust characteristics of a double-sided high temperature superconducting linear synchronous motor with a high temperature superconducting magnetic suspension system', Journal of Applied Physics, vol. 109, no. 7, pp. 073916-073916.
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An electromagnetic design of a double-sided high temperature superconducting (HTS) linear synchronous motor (HTSLSM) with an HTS bulk magnet secondary is introduced in this paper. A HTS magnetic suspension system is applied to replace the sliding rail to levitate the secondary mover resulting in the HTSLSM moving without sliding friction. The thrust model of the HTSLSM is built using a magnetic circuit method and the thrust characteristics obtained from the model are compared with finite element analysis and practical testing results. The theoretical analysis on the prototype has also been verified by measurements.
Jin, JX, Zheng, LH, Guo, YG & Zhu, JG 2011, 'Performance Characteristics of an HTS Linear Synchronous Motor With HTS Bulk Magnet Secondary', IEEE Transactions on Industry Applications, vol. 47, no. 6, pp. 2469-2477.
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A single-sided high-temperature superconducting (HTS) linear synchronous motor (HTSLSM) with an HTS bulk magnet array as its secondary has been developed, and a split pulse coil magnetization system is used to magnetize the secondary HTS bulks with alternating magnetic poles. The electromagnetic parameters of the HTSLSM have been calculated to verify its performance. The HTSLSM is incorporated with a developed control system based on the voltage space vector pulsewidth modulation strategy implemented by a computer-software-controlled platform. A compositive experimental testing system has also been developed to measure the thrust and normal force of the HTSLSM. The traits of the thrust and normal force have been comprehensively identi?ed experimentally, and the results from the experiments and analysis would bene?t the electromagnetic design and the control scheme development for the HTSLSM.
Keast, VJ, Birt, K, Koch, CT, Supansomboon, S & Cortie, MB 2011, 'The role of plasmons and interband transitions in the color of AuAl2, AuIn2, and AuGa2', APPLIED PHYSICS LETTERS, vol. 99, no. 11.
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Lem, LLC, Ton-That, C & Phillips, MR 2011, 'Distribution of visible luminescence centers in hydrogen-doped ZnO', JOURNAL OF MATERIALS RESEARCH, vol. 26, no. 23, pp. 2912-2915.
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ZnO crystals have been investigated by scanning cathodoluminescence microscopy and spectroscopy at 80 K following hydrogen incorporation by plasma exposure. The intensity of the ZnO near-band-edge (NBE) emission is greatly enhanced while the defect-related green emission is quenched following plasma treatment. These effects are attributed to the passivation of zinc vacancies by hydrogen. The green and yellow intensities and their intensity ratios to the NBE vary with excitation depth for both undoped and H-doped ZnO crystals. The intensities of the green and yellow emissions exhibit sublinear dependencies on electron beam excitation density while the NBE intensity increases linearly with the excitation density. These saturation effects with increasing excitation density must be taken into account when assessing defects in ZnO by luminescence characterization. © Copyright Materials Research Society 2011.
Li, Y, Lin, ZW, Liu, H, Wang, Y, Guo, Y, Zhu, J & Yang, Q 2011, 'Three-dimensional magnetic properties of soft magnetic composite material at different frequencies', Journal of Applied Physics, vol. 109, no. 7, pp. 07B503-07B503.
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Due to their intrinsic isotropic magnetic properties, soft magnetic composite (SMC) materials are applied in electrical machines in which the magnetic energy can be transported in three dimensions (3-D). However, in real applications, complicated magnetic properties such as anisotropy and nonlinearity, are found, in particular, at ahigh frequency range. This paper studies the 3-D magnetic properties of SMC materials under complicated magnetizations, such as circular, elliptical, and spherical excitations. The magnetic flux density vector B loci, magnetic field strength vector H loci, and core losses at magnetization frequencies ranging from 50–1000 Hz were measured and discussed using an improved 3-D testing system. Experimental results show that rotational core losses are greater than alternating losses at the same magnitude of flux density. In addition, rotational loss increases sharply around the saturation point, but is not observed in alternating loss.
Li, Y, Zhu, J, Yang, Q, Lin, ZW, Guo, Y & Zhang, C 2011, 'Study on Rotational Hysteresis and Core Loss Under Three-Dimensional Magnetization', IEEE Transactions on Magnetics, vol. 47, no. 10, pp. 3520-3523.
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In this paper, magnetic properties of soft magnetic composite (SMC) materials under alternating and various rotational magnetizations have been properly measured, modeled, and analyzed at typical frequencies of 5, 50, and 500 Hz. The relationship between the magnetic flux density vector B and magnetic field strength vector H has been systemically studied when the B loci are well controlled to be circles and ellipses in three orthogonal planes of the three-dimensional (3-D) tester. The core loss features against magnetic flux densities with alternating and rotational magnetizations are also compared and analyzed. It is found that the rotational core losses are nearly twice of the alternating core losses at the same magnitude of flux density. Experimental results show that SMC materials have good 3-D features, and great potential for application in rotational magnetic flux machines.
Lin, ZW, Li, YJ, Zhu, JG, Wang, XL, Dou, SX, Guo, YG, Lei, G, Wang, Y, Philips, M, Cortie, M, Li, YC, Choi, K-Y & Shi, X 2011, 'Visualization of vortex motion in FeAs-based BaFe(1.9)Ni(0.1)As(2) single crystal by means of magneto-optical imaging (vol 109, 07E142, 2011)', JOURNAL OF APPLIED PHYSICS, vol. 109, no. 10.
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Lin, ZW, Li, YJ, Zhu, JG, Wang, XL, Dou, SX, Guo, YG, Lei, G, Wang, Y, Philips, M, Cortie, M, Li, YC, Choi, K-Y & Shi, X 2011, 'Visualization of vortex motion in FeAs-based BaFe1.9Ni0.1As2 single crystal by means of magneto-optical imaging', JOURNAL OF APPLIED PHYSICS, vol. 109, no. 7, pp. 0-0.
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Superconductivity has been found in newly discovered iron-based compounds. This paper studies the motion of magnetic vortices in BaFe1.9Ni 0.1As2 single crystal by means of the magneto-optical imaging technique. A series of magneto-optical images reflecting magnetic flux distribution at the crystal surface were taken when the crystal was zero-field cooled to 10 K. The behavior of the vortices, including penetration into and expulsion from the single crystal with increasing and decreasing external fields, respectively, is discussed. The motion behavior is similar to that observed in high-Tc superconducting cuprates with strong vortex pinning; however, the flux-front is irregular due to randomly distributed defects in the crystal. © 2011 American Institute of Physics.
Liu, H, Wang, G, Liu, J, Qiao, S & Ahn, H 2011, 'Highly ordered mesoporous NiO anode material for lithium ion batteries with an excellent electrochemical performance', JOURNAL OF MATERIALS CHEMISTRY, vol. 21, no. 9, pp. 3046-3052.
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In this work, we have synthesized highly ordered mesoporous NiO materials by a nanocasting method using mesoporous silica KIT-6 as the hard templates. Mesoporous NiO particles were characterized by small angle X-ray diffraction (XRD), nitrogen adsorption/desorption, and transmission electron microscopy (TEM). The results demonstrated that the as-prepared mesoporous NiO had an ordered Ia3d symmetric mesostructure, with a high surface area of 96 m 2/g. Mesoporous NiO materials were tested as an anode material for lithium ion batteries, exhibiting much lower activation energy (20.75 kJ mol-1) compared to the bulk NiO (45.02 kJ mol-1). We found that the mesoporous NiO electrode has higher lithium intercalation kinetics than its bulk counterpart. The specific capacity of mesoporous NiO after 50 cycles was maintained 680 mAh/g at 0.1 C, which was much higher than that of the commercial bulk NiO (188 mAh/g). Furthermore, at a high rate of 2C, the discharge capacity of mesoporous NiO was as high as 515 mAh/g, demonstrating the potential to be used for high power lithium ion batteries. © The Royal Society of Chemistry 2011.
Liu, J, Qiao, SZ, Liu, H, Chen, J, Orpe, A, Zhao, D & Max Lu, GQ 2011, 'Extension of The Stober Method to the Preparation of Monodisperse Resorcinol-Formaldehyde Resin Polymer and Carbon Spheres', ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, vol. 50, no. 26, pp. 5947-5951.
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Sphere we go: Monodisperse resorcinol formaldehyde (RF) resin polymer spheres with finely tunable particle size ranging from 200 to 1000 nm (see pictures) are prepared by an extension of the Stöber method. Pyrolysis of the RF spheres at 600°C under N 2 atmosphere yields uniform carbon spheres with a volume shrinkage of 19%.
Lockrey, MN & Phillips, MR 2011, 'Characterisation of the optical properties of InGaN MQW structures using a combined SEM and CL spectral mapping system', Journal of Semiconductors, vol. 32, no. 1, pp. 012001-012001.
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We demonstrate the ability of a combined scanning electron microscope and cathodoluminescence (CL) spectral mapping system to provide important spatially resolved information. The degree of inhomogeneity in spectral output across a multi-quantum well sample is measured using the SEM-CL system as well as measuring the efficiency roll-off with increasing carrier concentration. The effects of low energy electron beam modification on the InGaN/GaN multi quantum wells have also been characterized.
Lu, Q, Yu, M, Ye, Y, Fang, Y & Zhu, J 2011, 'Thrust Force of Novel PM Transverse Flux Linear Oscillating Actuators With Moving Magnet', IEEE Transactions on Magnetics, vol. 47, no. 10, pp. 4211-4214.
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This paper investigates the thrust forces of two novel permanent magnet transverse flux linear oscillating actuators (TFLOAs), one with moving magnet and the other moving both magnet and iron core, for pump and compressor drives. Different from the conventional linear actuators, the lamination construction of the TFLOAs is similar to that of a normal rotating motor, which is easy to stack. Based on a simple magnetic circuit model taking into account the interpole leakage flux, the thrust forces are deduced analytically. The predicted results are verified by the finite element analyses and validated by experiments. It is shown that the thrust force performances of both TFLOAs are similar, whereas the former has a lower thrust force density and higher resonant frequency.
Ma, R, Bullock, E, Maynard, P, Reedy, B, Shimmon, R, Lennard, C, Roux, C & McDonagh, A 2011, 'Fingermark detection on non-porous and semi-porous surfaces using NaYF4:Er,Yb up-converter particles', FORENSIC SCIENCE INTERNATIONAL, vol. 207, no. 1-3, pp. 145-149.
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This article describes the first use of an anti-Stokes material, or up-converter, for the development of latent fingermarks on a range of non-porous surfaces. Anti-Stokes materials can absorb long-wavelength light and emit light at a shorter wavelength. This property is unusual in both natural and artificial materials and so fingermark detection techniques based on anti-Stokes luminescence are potentially sensitive and selective. Latent fingermarks on luminescent and non-luminescent substrates, including Australian polymer banknotes (a well-known 'difficult' surface), were developed with sodium yttrium tetrafluoride doped with erbium and ytterbium (NaYF4:Er,Yb) by dry powder, wet powder, and cyanoacrylate staining techniques. This study illustrates the potential of up-converter phosphors for the detection of latent fingermarks. © 2010 Elsevier Ireland Ltd.
Meng, X, Wang, S, Qiu, J, Zhang, Q, Zhu, JG, Guo, Y & Liu, D 2011, 'Robust Multilevel Optimization of PMSM Using Design for Six Sigma', IEEE Transactions on Magnetics, vol. 47, no. 10, pp. 3248-3251.
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In this paper, a robust optimization method based on design for six sigma (DFSS) is combined to the optimization of a surface mounted permanent synchronous machine (PMSM) by using multilevel genetic algorithm (MLGA). First, MLGA and DFSS are introduced in the robust optimization. Second, by taking into account the tolerances of the motor products, important input parameters could be varied with six sigma distribution and Monte Carlo simulation (MCS) method is used to reduce the calculation cost. Third, to verify the new algorithm, the presented algorithm is applied to the optimization of a PMSM. The results compared with those of traditional GA and MLGA and the discussion of the robust optimization combined with MLGA are presented. © 2011 IEEE.
Moezzi, A, Cortie, M & McDonagh, A 2011, 'Aqueous pathways for the formation of zinc oxide nanoparticles', DALTON TRANSACTIONS, vol. 40, no. 18, pp. 4871-4878.
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We examine the effect of reactant concentrations, temperatures and feeding methods on the morphology of ZnO formed when reacting solutions of ZnSO4 and NaOH. The catalytic effect of hydroxide in excess relative to the stoichiometric ratio is considered. It is shown that, having fixed other reaction conditions, the end-products, particle structures and size strongly depend on the mole ratio of the precursors. The presence of zinc salt hydroxide species was confirmed at sub-stoichiometric ratios in slightly acidic conditions. At the stoichiometric ratio both zinc hydroxide and zinc oxide are formed, while only zinc oxide forms in an excess of hydroxide. The method of feeding the reactants into the reaction vessel also has a strong influence on the end-product properties, as does the reaction temperature. By control of these parameters the specific surface area could be varied from 10 to 33 m2 g-1, the particle shape could be varied from equiaxed, through to star-like and needle-like, and the particle size may be varied from 50 to over 300 nm.
Pissuwan, D, Niidome, T & Cortie, MB 2011, 'The forthcoming applications of gold nanoparticles in drug and gene delivery systems', JOURNAL OF CONTROLLED RELEASE, vol. 149, no. 1, pp. 65-71.
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The unique optical, chemical, and biological properties of gold nanoparticles have resulted in them becoming of clinical interest in several applications including drug and gene delivery. The attractive features of gold nanoparticles include their surface plasmon resonance, the controlled manner in which they interact with thiol groups, and their non-toxic nature. These attributes can be exploited to provide an effective and selective platform to obtain a targeted intracellular release of some substance. The use of gold nanoparticles can also increase the stability of the payload. Here we review recent advances in the use of gold nanoparticles in drug and gene delivery systems. The topics of surface modification, site-specificity and drugs and gene and gene delivery are discussed.
Porkovich, AJ, Arnold, MD, Kouzmina, G, Hingley, B, Dowd, A & Cortie, MB 2011, 'Calorimetric Sensor for Use in Hydrogen Peroxide Aqueous Solutions', SENSOR LETTERS, vol. 9, no. 2, pp. 695-697.
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A sensor for characterising aqueous solutions of hydrogen peroxide is described. The sensor is based on the calorimetrie signal obtained when catalysing the decomposition of H2O2. The system is quick and simple, and is suitable for determinations of H2O2 concentration between 0% and at least 50% (w/w). Copyright © 2011 American Scientific Publishers. All rights reserved.
Salam, S, Islam, M, Alam, M, Akram, A, Ikram, M, Mahmood, A, Khan, M & Mujahid, M 2011, 'The effect of processing conditions on the structural morphology and physical properties of ZnO and CdS thin films produced via sol–gel synthesis and chemical bath deposition techniques', Advances in Natural Sciences: Nanoscience and Nanotechnology, vol. 2, no. 4, pp. 045001-045001.
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Abstract Cadmium sulfide (CdS) and zinc oxide (ZnO) are used in thin film solar cells as buffer layer and transparent conducting oxide, respectively. The effect of annealing conditions on the morphology and physical properties of CdS and ZnO films prepared using chemical bath deposition and sol–gel synthesis techniques, respectively, was investigated. CdS films obtained from the chemical bath deposition (CBD) process were found to be polycrystalline with dense granular morphology. Electrical characterization of the films annealed at 400 °C for 10 min yielded values of 2.2×10−3 Ω cm and 8.3×1012 cm −3 for resistivity and carrier concentration, respectively. Scanning electron microscopy (SEM) and x-ray diffraction (XRD) studies of intrinsic zinc oxide (i-ZnO) films revealed flake-like morphology and transformation of the as-deposited amorphous structure into a hexagonal wurtzite crystal structure upon annealing at 500 °C for 2 h. Optical and electrical characterization results showed that such films had ∼80% transmittance and resistivity values as low as 6.4×102 Ω cm. These films are being explored for fabrication and testing of copper-indium-gallium-(di)selenide (CIGS) thin film solar cells obtained from simple, cost-effective, solution-based synthesis routes.
Salisa, AR, Zhang, N & Zhu, JG 2011, 'A Comparative Analysis of Fuel Economy and Emissions Between a Conventional HEV and the UTS PHEV', IEEE Transactions on Vehicular Technology, vol. 60, no. 1, pp. 44-54.
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Unlike conventional hybrid electric vehicles (HEVs), the novel powertrain configuration of the University of Technology, Sydney (UTS) plug-in HEV (PHEV) contains only one electric machine, which functions as either an electric motor or a generator in different time intervals specified by a special energy management strategy (EMS). This paper presents a comparative analysis of the fuel economy and the greenhouse gas (GHG) emissions between a conventional HEV and the UTS PHEV, which includes vehicle modeling, EMS development, and a simulation model of the conventional HEV, which is embedded in the advanced vehicle simulator, and the UTS PHEV simulation code. The fuel economy and the emissions, such as hydrocarbon, carbon monoxide, and nitrogen oxides, are computed, analyzed, and compared for the two standard drive cycles, i.e., 1) the high-speed highway drive cycle and 2) the low-speed city drive cycle, proposed by the U.S. Environmental Protection Agency and their combination. © 2010 IEEE.
Sastraruji, T, Chaiyong, S, Jatisatienr, A, Pyne, SG, Ung, AT & Lie, W 2011, 'Phytochemical Studies on Stemona aphylla: Isolation of a New Stemofoline Alkaloid and Six New Stemofurans', JOURNAL OF NATURAL PRODUCTS, vol. 74, no. 1, pp. 60-64.
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A new stemofoline alkaloid, (2'S)-hydroxy-(11S,12R)-dihydrostemofoline (3), new stemofurans M-R (8-13), and known compounds stemofoline (1), (2?S)-hydroxystemofoline (2), stemofuran E (4), stemofuran F (5), stemofuran J (6), and stilbostemin F (7) have been isolated from the root extracts of Stemona aphylla. The structures and relative configurations of these new compounds have been determined by spectroscopic data interpretation and from semisynthetic studies. These natural and semisynthetic alkaloids were tested for acetylcholinesterase inhibitory activities and were found to be 10-20 times less active than 1?,2?-didehydrostemofoline itself. Stemofurans 4, 6, 8, 11, and 13 were tested for their antibacterial and antifungal activities. Three of these showed antibacterial activities against MRSA with MIC values of 15.6 ?g/mL
Shane, DT, Rayhel, LH, Huang, Z, Zhao, J-C, Tang, X, Stavila, V & Conradi, MS 2011, 'Comprehensive NMR Study of Magnesium Borohydride', The Journal of Physical Chemistry C, vol. 115, no. 7, pp. 3172-3177.
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Spindler, X, Hofstetter, O, McDonagh, AM, Roux, C & Lennard, C 2011, 'Enhancement of latent fingermarks on non-porous surfaces using anti-L-amino acid antibodies conjugated to gold nanoparticles', CHEMICAL COMMUNICATIONS, vol. 47, no. 19, pp. 5602-5604.
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Enantioselective anti-l-amino acid antibodies conjugated to gold nanoparticles are shown to facilitate the detection of latent fingermarks by interacting with amino acids present in friction ridge secretions. This antibody-based system is particularly effective for the enhancement of aged and dried fingermarks on non-porous surfaces, an area unexploited by current techniques. © 2011 The Royal Society of Chemistry.
Sprouster, DJ, Ruffell, S, Bradby, JE, Williams, JS, Lockrey, MN, Phillips, MR, Major, RC & Warren, OL 2011, 'Structural characterization of B-doped diamond nanoindentation tips', JOURNAL OF MATERIALS RESEARCH, vol. 26, no. 24, pp. 3051-3057.
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Copyright © Materials Research Society 2011. We report on the electrical and structural properties of boron-doped diamond tips commonly used for in-situ electromechanical testing during nanoindentation. The boron dopant environment, as evidenced by cathodoluminescence (CL) microscopy, revealed significantly different boron states within each tip. Characteristic emission bands of both electrically activated and nonelectrically activated boron centers were identified in all boron-doped tips. Surface CL mapping also revealed vastly different surface properties, confirming a high amount of nonelectrically activated boron clusters at the tip surface. Raman microspectroscopy analysis showed that structural characteristics at the atomic scale for boron-doped tips also differ significantly when compared to an undoped diamond tip. Furthermore, the active boron concentration, as inferred via the Raman analysis, varied greatly from tip-to-tip. It was found that tips (or tip areas) with low overall boron concentration have a higher number of electrically inactive boron, and thus non-Ohmic contacts were made when these tips contacted metallic substrates. Conversely, tips that have higher boron concentrations and a higher number of electrically active boron centers display Ohmic-like contacts. Our results demonstrate the necessity to understand and fully characterize the boron environments, boron concentrations, and atomic structure of the tips prior to performing in situ electromechanical experiments, particularly if quantitative electrical data are required.
Su, D, Ahn, H & Wang, G 2011, 'Ab initio calculations on Li-ion migration in Li2FeSiO4 cathode material with a P21 symmetry structure', Applied Physics Letters, vol. 99, no. 14, pp. 141909-141909.
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We have systematically investigated the diffusion mechanism of Li ions in Li2FeSiO4 and its delithiated product LiFeSiO4 based on the P21 symmetry using the first principle method. Calculations on the energy barriers for possible spatial hopping pathways predicted that the activation barriers along the [101] direction and Li ion layer in the ac plane are relatively low, which can ensure the facile lithium diffusion along those directions. The results indicate that Li2FeSiO4 with the P21 symmetry is an ionic conductor for Li ions with two-dimensional diffusion.
Sun, B, Chen, Z, Kim, H-S, Ahn, H & Wang, G 2011, 'MnO/C core-shell nanorods as high capacity anode materials for lithium-ion batteries', JOURNAL OF POWER SOURCES, vol. 196, no. 6, pp. 3346-3349.
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MnO/C core-shell nanorods were synthesized by an in situ reduction method using MnO2 nanowires as precursor and block copolymer F127 as carbon source. Field emission scanning electron microscopy and transmission electron microscopy analysis indicated that a thin carbon layer was coated on the surfaces of the individual MnO nanorods. The electrochemical properties were evaluated by cyclic voltammetry and galvanostatic charge-discharge techniques. The as-prepared MnO/C core-shell nanorods exhibit a higher specific capacity than MnO microparticles as anode material for lithium ion batteries. © 2010 Elsevier B.V. All rights reserved.
Tian, H, Li, B, Wang, H, Li, Y, Wang, J, Zhao, S, Zhu, J, Wang, Q, Liu, W, Yao, X & Tang, Y 2011, 'A nanocontainer that releases a fluorescence sensor for cadmium ions in water and its biological applications', Journal of Materials Chemistry, vol. 21, no. 28, pp. 10298-10298.
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Traut, T, Kriel, FH, Zyl, WEV & Williams, DBG 2011, 'Chlorido{N-[2-(diphenylphosphanyl)benzyl]-1-(pyridin-2-yl)methanamine-κP}gold(I)', Acta Crystallographica Section E Structure Reports Online, vol. 67, no. 11, pp. m1625-m1625.
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In the title compound, [AuCl(C25H23N2P)], the AuI atom is in a typical almost linear coordination environment defined by phosphane P and Cl atoms [bond angle = 175.48 (4)°]. Helical supra-molecular chains along the b axis and mediated by N - H⋯Cl hydrogen bonds feature in the crystal packing. © Traut et al. 2011.
Ung, AT, Pyne, SG, Jeoffreys, GR, Skelton, BW & White, AH 2011, 'ChemInform Abstract: Synthesis of 2‐Acetyl‐5‐(1,2,3,4,5,6‐hexahydroxyhexyl)thiazoles.', ChemInform, vol. 42, no. 29, pp. no-no.
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AbstractThe synthesis of two diastereomers of the title compound involves the coupling of 5‐lithiated 2‐(1,1‐dimethoxyethyl)thiazole (VI) with a Weinreb amide (V) derived from gluconolacetone, followed by asymmetric reduction of the ketone functionality.
Ung, AT, Pyne, SG, Jeoffreys, GR, Skelton, BW & White, AH 2011, 'Synthesis of 2-acetyl-5-(1,2,3,4,5,6-hexahydroxyhexyl)thiazoles', MONATSHEFTE FUR CHEMIE, vol. 142, no. 3, pp. 297-303.
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The syntheses of two diastereoisomers of 2-acetyl-5-(1,2,3,4,5,6-hexahydroxyhexyl) thiazole are reported. The synthesis of these diastereoisomers involved the coupling of 5-metallated 2-(1,1-dimethoxyethyl)thiazole with a Weinreb amide derived from d-gluconolactone, followed by asymmetric reduction of the ketone thus prepared. The stereochemistries and structures of some key compounds were determined by single-crystal X-ray structural analysis.
Wagner, MR, Callsen, G, Reparaz, JS, Schulze, J-H, Kirste, R, Cobet, M, Ostapenko, IA, Rodt, S, Nenstiel, C, Kaiser, M, Hoffmann, A, Rodina, AV, Phillips, MR, Lautenschlaeger, S, Eisermann, S & Meyer, BK 2011, 'Bound excitons in ZnO: Structural defect complexes versus shallow impurity centers', PHYSICAL REVIEW B, vol. 84, no. 3.
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ZnO single crystals, epilayers, and nanostructures often exhibit a variety of narrow emission lines in the spectral range between 3.33 and 3.35 eV which are commonly attributed to deeply bound excitons (Y lines). In this work, we present a comprehensive study of the properties of the deeply bound excitons with particular focus on the Y0 transition at 3.333 eV. The electronic and optical properties of these centers are compared to those of the shallow impurity related exciton binding centers (I lines). In contrast to the shallow donors in ZnO, the deeply bound exciton complexes exhibit a large discrepancy between the thermal activation energy and localization energy of the excitons and cannot be described by an effective mass approach. The different properties between the shallow and deeply bound excitons are also reflected by an exceptionally small coupling of the deep centers to the lattice phonons and a small splitting between their two electron satellite transitions. Based on a multitude of different experimental results including magnetophotoluminescence, magnetoabsorption, excitation spectroscopy (PLE), time resolved photoluminescence (TRPL), and uniaxial pressure measurements, a qualitative defect model is developed which explains all Y lines as radiative recombinations of excitons bound to extended structural defect complexes. These defect complexes introduce additional donor states in ZnO. Furthermore, the spatially localized character of the defect centers is visualized in contrast to the homogeneous distribution of shallow impurity centers by monochromatic cathodoluminescence imaging. A possible relation between the defect bound excitons and the green luminescence band in ZnO is discussed. The optical properties of the defect transitions are compared to similar luminescence lines related to defect and dislocation bound excitons in other II-VI and III-V semiconductors. © 2011 American Physical Society.
Wang, G, Liu, H, Liu, J, Qiao, S, Lu, GM, Munroe, P & Ahn, H 2011, 'ChemInform Abstract: Mesoporous LiFePO4/C Nanocomposite Cathode Materials for High Power Lithium Ion Batteries with Superior Performance.', ChemInform, vol. 42, no. 6, pp. no-no.
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AbstractHexagonally ordered mesoporous LiFePO4/C nanocomposites, in which LiFePO4 nanoparticles are embedded in conductive and interconnected carbon networks are synthesized from aqueous solutions of LiOAc, Fe(OAc)2, and NH4H2PO4 in the presence of mesoporous carbons as templates (Ar, 350 °C) followed by sintering at 700 °C for 10 h in a H2/Ar gas mixture.
Wang, Y, Sun, B, Park, J, Kim, W-S, Kim, H-S & Wang, G 2011, 'Morphology control and electrochemical properties of nanosize LiFePO4 cathode material synthesized by co-precipitation combined with in situ polymerization', JOURNAL OF ALLOYS AND COMPOUNDS, vol. 509, no. 3, pp. 1040-1044.
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Nanosize carbon coated LiFePO4 cathode material was synthesized by in situ polymerization. The as-prepared LiFePO4 cathode material was systematically characterized by X-ray diffraction, thermogravimetric- differential scanning calorimetry, X-ray photo-electron spectroscopy, field-emission scanning electron microscopy, and transmission electron microscopy techniques. Field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) images revealed that the morphology of the LiFePO4 consists of primary particles (40-50 nm) and agglomerated secondary particles (100-110 nm). Each particle is evenly coated with an amorphous carbon layer, which has a thickness around 3-5 nm. The electrochemical properties were examined by cyclic voltammetry and charge-discharge testing. The as-prepared LiFePO4 can deliver an initial discharge capacity of 145 mAh/g, 150 mAh/g, and 134 mAh/g at 0.2 C, 1 C, and 2 C rates, respectively, and exhibits excellent cycling stability. At a higher C-rate (5 C) a slight capacity loss could be found. However after being charge-discharge at lower C-rates, LiFePO4 can be regenerated and deliver the discharge capacity of 145 mAh/g at 0.2 C. © 2010 Elsevier B.V. All rights reserved.
Williams, DBG, Kotze, PDR, Ferreira, AC & Holzapfel, CW 2011, 'Phosphine-Borane Complexes: in situ Deprotection and Application as Ligands in the Rh- or Pd-Catalysed Hydroformylation Reaction', Journal of the Iranian Chemical Society, vol. 8, no. 1, pp. 240-246.
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Triarylphosphine-borane complexes are directly useful in the Rh-catalysed hydroformylation reaction of 1-octene (or Pdcatalysed hydroformylation of 1-pentene). Mild reaction conditions provide similar yields and selectivities of the anticipated aldehyde products to reactions making use of the corresponding free phosphines as ligands. The mono- or bidentate P-B adducts undergo in situ CO-mediated deprotection the produce the free phosphine ligands. The results demonstrate that phosphine-borane complexes may be directly applied to carbonylation reactions without a prior deprotection step, with little to no change in the reaction outcome.
Wuhrer, R, Moran, K, Dredge, P & Phillips, M 2011, 'Use of X-Ray Mapping to Investigate Art Works Before their Restoration', Microscopy and Microanalysis, vol. 17, no. S2, pp. 1790-1791.
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Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.
Xiao, H, Qiu, J, Wang, S, Zhang, Q, Gong, W, Xin, Y, Zhu, JG & Guo, Y 2011, 'Analysis of Transient Overvoltage in 220 kV Saturated Core HTS FCL', IEEE Transactions on Magnetics, vol. 47, no. 10, pp. 2620-2623.
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Saturated Core High Temperature Superconducting (HTS) Fault Current Limiter (FCL) is one kind of limiters that can work effectively on short-circuit current limitation. In this paper, an equivalent circuit model depending on ac coil of HTS FCL is built for voltage distribution analysis under transient overvoltage. The equivalent circuit components, such as the capacitances and inductances, are calculated by using ?nite element method. The voltage distribution and oscillation analysis of ac coil may bene?t to the insulation design of HTS FCL.
Xu, J, Sun, Z, Jia, L, Li, B, Zhao, L, Liu, X, Ma, Y, Tian, H, Wang, Q, Liu, W & Tang, Y 2011, 'Visible light sensitized attapulgite-based lanthanide composites: microstructure, photophysical behaviour and biological application', Dalton Transactions, vol. 40, no. 48, pp. 12909-12909.
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Xu, W, Zhu, J, Zhang, Y, Guo, Y & Lei, G 2011, 'New Axial Laminated-Structure Flux-Switching Permanent Magnet Machine With 6/7 Poles', IEEE TRANSACTIONS ON MAGNETICS, vol. 47, no. 10, pp. 2823-2826.
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In this paper, one new axially laminated-structure ?ux-switching permanent magnet machine (ALSFSPMM) with 6/7 (stator/rotor) poles is proposed. Different from the conventional ?ux-switching permanent magnet machine (FSPMM), the stator and rotor of ALSFSPMM are laminated parallel to the axial direction, which can make full use of PM ?ux linkage, decrease part magnetic saturation, and reduce the iron loss particularly in the range of high speed. By the 2-D model prediction of ?nite element algorithm (FEA), ALSFSPMM has lower cogging torque, stronger ?ux weakening ability, greater torque density, higher ef?ciency, etc., and hence it is an ideal candidate for the drive system of plug-in hybrid electrical vehicle (PHEV).
Yang, G, Chen, X, Lei, G, Shao, KR, Guo, Y, Zhu, J & Lavers, JD 2011, 'Domain Decomposition Combined Radial Basis Function Collocation Method to Solve Transient Eddy Current Magnetic Problems With Moving Conductors', IEEE TRANSACTIONS ON MAGNETICS, vol. 47, no. 10, pp. 2939-2942.
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Radial basis function (RBF) collocation method is a kind of pure meshless numerical method and has been applied to solve static and transient electromagnetic problems. Especially, it shows a great advantage in the computation of moving conductor eddy current magnetic problems. To simulate the conductor movement, the field equations are decoupled with superposition principle and solved by time-domain iteration under moving coordinate systems. One problem is that the coefficient matrix of RBF governing equations, which needs to be computed in each iteration step, is full. As the number of RBF nodes increases, the computational capacity will grow rapidly. The domain decomposition method (DDM), which divides the solving domain into several subdomains, could be conveniently combined with RBF collocation method. This paper first applies DDM combined RBF collocation method to compute transient eddy current magnetic field problems with moving conductors. With this novel method, the iteration only proceeds in the subdomains containing conductors. And the magnetic field in the subdomains without conductors needs to be computed just once before the iteration. The dimension of the coefficient matrix computed in the iteration is only determined by the number of nodes in the corresponding subdomains and on the interfaces. An engineering problem is computed to show that the DDM combined RBF collocation method is much more efficient than the normal one.
Yisgedu, TB, Chen, X, Lingam, HK, Huang, Z, Highley, A, Maharrey, S, Behrens, R, Shore, SG & Zhao, J-C 2011, 'Synthesis, Structural Characterization, and Thermal Decomposition Study of Mg(H2O)6B10H10·4H2O', The Journal of Physical Chemistry C, vol. 115, no. 23, pp. 11793-11802.
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Yongchang Zhang & Jianguo Zhu 2011, 'A Novel Duty Cycle Control Strategy to Reduce Both Torque and Flux Ripples for DTC of Permanent Magnet Synchronous Motor Drives With Switching Frequency Reduction', IEEE Transactions on Power Electronics, vol. 26, no. 10, pp. 3055-3067.
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Conventional switching-table-based direct torque control (DTC) presents large torque and flux ripples as well as variable switching frequency. Many methods have been proposed to tackle the aforementioned problems, among which duty cycle control is a kind
Yongchang Zhang & Jianguo Zhu 2011, 'Direct Torque Control of Permanent Magnet Synchronous Motor With Reduced Torque Ripple and Commutation Frequency', IEEE Transactions on Power Electronics, vol. 26, no. 1, pp. 235-248.
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In conventional direct torque controlled (DTC) permanent magnet synchronous motor drive, there is usually undesired torque and flux ripple. The existing literature have proposed some methods to reduce torque and flux ripple by optimizing the duty ratio o
Zhang, Y, Zhao, Z & Zhu, J 2011, 'A Hybrid PWM Applied to High-Power Three-Level Inverter-Fed Induction-Motor Drives', IEEE Transactions on Industrial Electronics, vol. 58, no. 8, pp. 3409-3420.
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A hybrid pulsewidth modulation (PWM), combining the merits of both space-vector PWM (SVPWM) and selective harmonic elimination (SHE) PWM (SHEPWM), is proposed for three-level neutral-point-clamped (NPC) inverter-fed high-power adjustable-speed drives, wh
Zhang, Y, Zhu, J, Xu, W & Guo, Y 2011, 'A Simple Method to Reduce Torque Ripple in Direct Torque-Controlled Permanent-Magnet Synchronous Motor by Using Vectors With Variable Amplitude and Angle', IEEE Transactions on Industrial Electronics, vol. 58, no. 7, pp. 2848-2859.
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In this paper, a modified direct torque control (DTC) for permanent-magnet synchronous machines, which enables important torque- and flux-ripple reduction by using voltage vectors with variable amplitude and angle, is proposed. In the proposed DTC, the amplitudes of torque and flux errors are differentiated and employed to regulate the amplitude and angle of the output voltage vectors online, which are finally synthesized by space-vector modulation (SVM). Two simple formulas are developed to derive the amplitude and angle of the commanding voltage vectors from the errors of torque and flux only. The conventional switching table and hysteresis controllers are eliminated, and a fixed switching frequency is obtained with the help of SVM. Stator flux is estimated from an improved voltage model, which is based on a low-pass filter with compensations of the amplitude and phase. The proposed DTC is comparatively investigated with the existing SVM-DTC from the aspects of theory analysis, computer simulation, and experimental validation. The simulation and experimental results prove that the proposed DTC is very simple and provides excellent steady-state response, quick dynamic performance, and strong robustness against external disturbance and control-parameter variations.
Zhu, JG, Guo, YG, Lin, ZW, Li, YJ & Huang, YK 2011, 'Development of PM Transverse Flux Motors With Soft Magnetic Composite Cores', IEEE Transactions on Magnetics, vol. 47, no. 10, pp. 4376-4383.
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Compared with the conventional fixed speed drive, a major factor that handicaps the wide acceptance of variable speed drive with high ef?ciency permanent magnet (PM) motors is its high cost. This paper presents an effort to reduce the material and manufacturing costs of PM motors by using the soft magnetic composite (SMC), and the highly matured powder metallurgic technology. Because the SMCs magnetic properties are quite different from that of the traditional silicon steel sheets, special efforts have been made on measurement and modelling of vectorial magnetic properties, electrical machine topologies, and drive schemes in order to make the best use of the material. Various PM SMC motors of transverse ?ux topologies have been designed, fabricated, and tested. The detailed results are presented and discussed
Hsing, A, Iacopi, F, Lehr, MU, Geisler, H, Machani, K, Ryan, V, Paul, J, Besser, P & Dauskardt, R 1970, 'Mechanical microprobing of Cu pillars and influence of dielectric properties on chip-package interaction', Advanced Metallization Conference (AMC), pp. 52-53.
Hu, J, Zhu, J & Platt, G 1970, 'Smart grid — The next generation electricity grid with power flow optimization and high power quality', 2011 International Conference on Electrical Machines and Systems, 2011 International Conference on Electrical Machines and Systems (ICEMS), IEEE, China, pp. 1-6.
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As the demand for electricity power increases rapidly while the fossil fuels decrease year by year, taking use of renewable resources seems very necessary. However, due to the discontinuous nature of the renewable resources and the hierarchical topology of the existing grid, the power quality and grid stability will deteriorate as more and more distributed generations (DGs) connected to the grid. It is a good idea to combine local utilization, local consumption, energy storage and DGs to form grid-friendly micro grid, these micro grids are then assembled to be an intelligent power system - Smart Grid. It can optimize the power flow and integrate power generation and consumption effectively. Most importantly, the power quality and grid stability can be improved greatly. This paper depicts how smart grid addresses the current issues of power system. It also figures out the key technologies and expectation of the smart grid.
Hu, J, Zhu, J, Dorrell, DG & IEEE 1970, 'A Comparative Study of Direct Power Control of AC/DC Converters for Renewable Energy Generation', IECON 2011: 37TH ANNUAL CONFERENCE ON IEEE INDUSTRIAL ELECTRONICS SOCIETY, Annual Conference of the IEEE Industrial Electronics Society, IEEE, Australia, pp. 3453-3458.
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Direct power control (DPC) has been proposed and well developed for its distinguished advantages such as simplicity, robustness, excellent steady-state and dynamic response. This paper presents a comparative study of DPC strategies of AC/DC converters for renewable energy generation. First, the advantages and disadvantages of each strategy are given by control theory investigation. In addition, virtual flux concept is studied and a voltage sensorless algorithm for SVM-based predictive DPC is proposed. Furthermore, steady-state and transient performance will be analyzed in simulation in terms of active and reactive power ripples, total distortion harmonic (THD) of line currents, sampling frequency, switching frequency tracking behavior, etc. Finally, a comprehensive comparison is drawn, based on which the most suitable strategy can be chosen according to different applications.
Hu, J, Zhu, J, Ma, Q & Zhang, Y 1970, 'Predictive direct virtual torque control of doubly fed induction generator for grid synchronization', 2011 International Conference on Electrical Machines and Systems, 2011 International Conference on Electrical Machines and Systems (ICEMS), IEEE, China, pp. 1-6.
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Predictive direct torque control (PDTC) has been proposed and well developed because of its excellent steady-state and transient performance. On the other hand, due to the elimination of proportional-integral regulator, direct virtual torque control was presented and proved to be an effective method for doubly fed induction generator (DFIG) grid synchronization. This paper proposes a novel DFIG grid synchronization strategy combining the merits of PDTC and virtual torque concept. The control system is very simple and robust while the smooth and fast grid synchronization is achieved.
Hu, J, Zhu, J, Zhang, Y & Guo, Y 1970, 'Predictive direct power control of doubly fed induction generator with power ripples reduction and one step delay compensation for wind power generation', 2011 International Conference on Electrical Machines and Systems, 2011 International Conference on Electrical Machines and Systems (ICEMS), IEEE, Beijing, China, pp. 1-6.
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Hu, J, Zhu, J, Zhang, Y, Platt, G, Dorrell, DG, Ma, Q & IEEE 1970, 'Predictive Direct Control of Doubly Fed Induction Generator for Grid Synchronization in Wind Power Generation', 2011 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE), IEEE Energy Conversion Congress and Exposition, The Institute of Electrical and Electronics Engineers, Inc., Phoenix, AZ, USA, pp. 2381-2388.
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Predictive direct control has been proposed and well developed because of its combination of simplicity and excellent steady-state and transient performance. This paper presents a predictive direct control strategy of doubly fed induction generator (DFIG) for grid synchronization. In no-load mode, predictive direct virtual torque control (PDVTC) is employed to meet the grid synchronization conditions. In grid-connected mode, the stator is connected to the grid, predictive direct power control (PDPC) is utilized with the purpose of flexible active and reactive power regulation. Furthermore, a rotor position sensorless scheme is proposed to make the control structure simpler during the grid synchronization process. The whole system is very simple and robust while the smooth and fast grid synchronization is achieved.
Hu, J, Zhu, J, Zhang, Y, Qishuang Ma & Youguang Guo 1970, 'Simple and robust predictive direct control of DFIG with low constant switching frequency and reduced torque and flux ripples', 2011 IEEE International Electric Machines & Drives Conference (IEMDC), Drives Conference (IEMDC), IEEE, Niagara Falls, ON, Canada, pp. 781-786.
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For conventional direct torque control (CDTC) methods, there are usually undesired torque and flux ripples mainly for two reasons. First, the vectors selected are not necessary the best. Secondly, one-step delay influence in digital implementation causes additional torque and flux ripples. This paper proposes a novel predictive direct torque control (PDTC) strategy of the doubly fed induction generator (DFIG). The proposed strategy aims to reduce torque and flux ripples effectively at low constant switching frequency by appropriately arranging two active vectors followed by one zero vector within one control period. Furthermore, one-step delay is compensated using a mode-based prediction scheme. Finally, the control system is simplified through further analysis of the transient slope of torque and flux without performance degradation. Simulation results validate the proposed strategy with excellent steady-state and transient performance, which makes it very suitable for wind power generation.
Islam, MR, Guo, Y & Zhu, JG 1970, 'Performance and cost comparison of NPC, FC and SCHB multilevel converter topologies for high-voltage applications', 2011 International Conference on Electrical Machines and Systems, 2011 International Conference on Electrical Machines and Systems (ICEMS), IEEE, Beijing, China, pp. 1-6.
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The rapid increase in global energy consumption and the impact of greenhouse gas emissions have accelerated the renewable energy technology into a more competitive area. Due to the variable nature of renewable energy resources and power demand by the consumers, grid based renewable generation has gained significant popularity in the world. High-voltage converter can interconnect the renewable systems to the grid directly without introducing a lossy, costly and bulky transformer. Three popular multilevel converter topologies: Neutral Point Clamped (NPC), Flying Capacitor (FC) and Series Connected H-Bridge (SCHB) have successfully made their way into the industry and therefore can be considered a mature and proven technology for low and medium voltage applications. But most of them are not suitable for high-voltage applications. This paper presents the comparison of a Five-Level (5L)-NPC, a 5LFC, a 5L-SCHB, an Eleven-Level (11L)-NPC, an 11L-FC and an 11L-SCHB topologies for an 11 kV Voltage Source Converter (VSC). The comparison is made in terms of number of semiconductors, semiconductor cost, Total Harmonic Distortion (THD), filter size and control complexity.
Islam, MR, Guo, Y & Zhu, JG 1970, 'Transformer-less local grid based 11 kV SCHB multilevel converter for renewable energy systems', 2011 International Conference on Electrical Machines and Systems, 2011 International Conference on Electrical Machines and Systems (ICEMS), IEEE, Beijing, China, pp. 1-6.
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Due to the variable nature of renewable energy resources and power demand by the consumers, it is difficult to operate a power system installed with only one type of renewable energy resource. The local grid based renewable generation may be the only solution to overcome this problem. In this regard, an 11 kV Series Connected H-Bridge (SCHB) multilevel Voltage Source Converter (VSC) is proposed, which is the transformer less, cost effective solution to interface the renewable generation system to the local grid directly. This paper presents the design, simulation and analysis of a Five Level (5L)-SCHB and an Eleven Level (11L)-SCHB VSC for an 11 kV local grid based renewable energy systems. The performance, cost, modulation scheme and harmonic spectra of the converter are the bases for analysis.
Islam, MR, Guo, Y, Zhu, JG, Dorrell, D & IEEE 1970, 'Design and Comparison of 11 kV Multilevel Voltage Source Converters for Local Grid Based Renewable Energy Systems', IECON 2011: 37TH ANNUAL CONFERENCE ON IEEE INDUSTRIAL ELECTRONICS SOCIETY, Annual Conference of the IEEE Industrial Electronics Society, IEEE, Melbourne, Australia, pp. 3596-3601.
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Because the availability of renewable energy is highly variable and the power demand by the consumers could have a very different characteristic, it is very desirable to connect a renewable generation system to the grid. In this respect, the 11 kV multilevel Voltage Source Converter (VSC) has no heavy transformer and is the cost effective solution to interfacing a renewable generation system to the local grid directly. This paper presents the design and comparison of a Five-Level Neutral Point Clamped (5L-NPC), a Five-Level Flying Capacitor (5L-FC), a Five-Level Series Connected H-Bridge (5L-SCHB), an Eleven-Level Neutral Point Clamped (11LNPC), an Eleven-Level Flying Capacitor (11L-FC), and an Eleven-Level Series Connected H-Bridge (5L-SCHB) VSC for an 11 kV local grid based converter. The cost of power semiconductors and capacitors, modulation schemes and harmonic spectra of the converters are the bases for comparison.
Islam, MR, Guo, YG & Zhu, JG 1970, 'H-bridge multilevel voltage source converter for direct grid connection of renewable energy systems', 2011 IEEE PES Innovative Smart Grid Technologies, 2011 IEEE PES Innovative Smart Grid Technologies (ISGT Australia), IEEE, Perth, Australia, pp. 1-7.
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The conventional approach based on low-voltage converter with power frequency transformer is commonly employed for grid connection of offshore renewable power generation systems. Because of the heavy weight and large size of the transformer, the system can be expensive and complex for installation and maintenance. As an alternative approach to achieve a compact and light direct grid connection, a high-voltage converter using series connected H-bridge (SCHB) multilevel converter topology is proposed in this paper. Since the SCHB converter requires a large number of isolated and balanced DC supplies, a high frequency transformer link is employed to couple the SCHB to the single low voltage DC supply. This paper presents the design and simulation of the proposed system.
Jian Bin Zeng, Guo, YG, Zhu, JG & Lin, ZW 1970, 'Magnetic hysteresis property of magneto-rheological fluid material under 2D fluxes', 2011 International Conference on Applied Superconductivity and Electromagnetic Devices, 2011 International Conference on Applied Superconductivity and Electromagnetic Devices (ASEMD), IEEE, Sydney, Australia, pp. 256-259.
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This paper systematically reports our recent study on the magnetic hysteresis property of magnetorheological (MR) fluid material under one dimension alternating and two dimension rotating magnetic field. The measurement was completed by a single sheet tester and a MR fluid sample container. The principle of measurement and the calibrating procedure of sensor coil are presented. The experiment results, such as H-B loop, H & B vector loci and lagging angle between H and B are analyzed and discussed. The results will be useful in the design of smart structure using MR material fluid. © 2011 IEEE.
Jin, J, Zheng, L, Xu, W, Guo, Y & Zhu, J 1970, 'Experimental study on thrust and normal force of a permanent magnet linear synchronous motor', 2011 International Conference on Electrical Machines and Systems, 2011 International Conference on Electrical Machines and Systems (ICEMS), IEEE, Beijing, China, pp. 1-6.
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Kajer, T, Hawkins, CL, Fu, S, Pattison, DI, Graham, GG & Davies, MJ 1970, 'Myeloperoxidase-Derived Oxidant Production and Biological Damage are Inhibited by Acetaminophen (Paracetamol) at Pharmacologically-Relevant Levels', FREE RADICAL BIOLOGY AND MEDICINE, 18th Annual Meeting of the Society-for-Free-Radical-Biology-and-Medicine (SFRBM), ELSEVIER SCIENCE INC, Atlanta, GA, pp. S89-S89.
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Lei, G, Guo, Y, Zhu, J, Li, K, Li, Y & Shao, KR 1970, 'Multiobjective electromagnetic devices design based on improved EDA with sequential optimization of the probability model', 2011 International Conference on Electrical Machines and Systems, 2011 International Conference on Electrical Machines and Systems (ICEMS), IEEE, Beijing, China, pp. 1-4.
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Li, YB, Lei, G, Guo, YG & Zhu, JG 1970, 'Optimization design of a voice coil actuator based on improved SOM', 2011 International Conference on Applied Superconductivity and Electromagnetic Devices, 2011 International Conference on Applied Superconductivity and Electromagnetic Devices (ASEMD), IEEE, Sydney, Australia, pp. 224-227.
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Voice coil actuator is a new kind of direct drive motor. It has many good performances, such as high acceleration and fast response. We present an improved sequential optimization method (SOM) and dimension reduction optimization method to design optimization a cylindrical voice coil actuator in this work. In the implementation, design of experiments (DOE) technique and Kriging approximate model are employed to improve the optimization efficiency. From the discussion, we can see that the proposed methods are very efficient. And computation cost of finite element analysis can be reduced remarkably (more than 2/3 of the cost has been saved) by the proposed methods.
Phillips, M, Manning, TJ, Nenstiel, C, Lockrey, MN, Ton-That, C & Hoffmann, AV 1970, 'High Temperature In-Situ Cathodoluminescence Studies of the Thermal Stability of Hydrogen in p-type Magnesium Doped Gallium Nitride', Microscopy and Microanalysis, Vol 17, Supplement 2, High Temperature In-Situ Cathodoluminescence Studies of the Thermal Stability of Hydrogen in p-type, Nashville, pp. 1-2.
Qing Fang Teng, Wei Zhong Zhang, Jian Guo Zhu & You Guang Guo 1970, 'Design of protection circuit for arc welding power supply', 2011 International Conference on Applied Superconductivity and Electromagnetic Devices, 2011 International Conference on Applied Superconductivity and Electromagnetic Devices (ASEMD), IEEE, Sydney, Australia, pp. 232-234.
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The paper discusses the design of protection circuits responsible for the reliability of arc welding power supply. The protection circuits include three parts, and they are soft-start circuit for anti-surge, circuit for eliminating transformer DC bias magnetic field and circuit for transient over-voltage suppression, respectively. The detail calculations about component parameters of these circuits are given. The transformer and the power devices in this paper are regarded as ideal devices. Meanwhile, their losses are neglected. The method can provide certain guide for improving reliability of protection circuit.
Qing Fang Teng, Wei Zhong Zhang, Jian Guo Zhu & You Guang Guo 1970, 'Modeling of arc welding power supply', 2011 International Conference on Applied Superconductivity and Electromagnetic Devices, 2011 International Conference on Applied Superconductivity and Electromagnetic Devices (ASEMD), IEEE, Sydney, Australia, pp. 228-231.
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This paper gives a method of establishing small-signal model for full-bridge inverter arc welding power supply via statespace averaging treatment and linearization method. On the basis of the model, the frequency response reflecting dynamical characteristics of arc welding power supply is analyzed by means of MATLAB. The simulation result has agreement with experiment result as regards dynamical property. The small signal frequent mathematical model established in the paper can reflect basic characteristic of practical arc welding power system.
Tian Shi Wang, Zhu, JG, You Guang Guo, Gang Lei & Xu, W 1970, 'Simulation and experimental studies of permanent magnet synchronous motor control methods', 2011 International Conference on Applied Superconductivity and Electromagnetic Devices, 2011 International Conference on Applied Superconductivity and Electromagnetic Devices (ASEMD), IEEE, Sydney, Australia, pp. 252-255.
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This paper presents simulation and experimental studies of permanent magnet synchronous motor (PMSM) control methods, including vector control (VC) or field oriented control (FOC), direct torque control (DTC) and model predictive control (MPC). The static and dynamic performance of each method are performed and compared in Matlab/Simulink and dSAPCE system.
Wang, T, Zhu, J & Zhang, Y 1970, 'Model predictive torque control for PMSM with duty ratio optimization', 2011 International Conference on Electrical Machines and Systems, 2011 International Conference on Electrical Machines and Systems (ICEMS), IEEE.
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This paper presents the application of model based predictive torque control (MPTC) with duty ratio optimization for permanent magnet synchronous motor (PMSM) drives. By using MPTC, significant reduction in torque and flux ripples can be achieved by selecting the voltage vector best satisfying the demands of torque and flux. Moreover, the MPTC drive system can maintain the performance by incorporating duty ratio optimization of the active vector with a lower sampling frequency. Simulation results are presented to demonstrate the effectiveness of the proposed schemes in this paper. © 2011 IEEE.
Xu, W, Zhu, J, Zhang, Y & Hu, J 1970, 'Cogging torque reduction for radially laminated flux-switching permanent magnet machine with 12/14 poles', IECON 2011 - 37th Annual Conference of the IEEE Industrial Electronics Society, IECON 2011 - 37th Annual Conference of IEEE Industrial Electronics, IEEE, Melbourne, VIC, pp. 3590-3595.
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Flux-switching permanent-magnet machine (FSPMM) offers high torque density, impressive flux weakening capability and mechanical ruggedness because of its distinctive configuration, and is potentially suitable for the application in the plug-in hybrid electric vehicle (PHEV). However, the FSPMM compared with other traditional machines commonly used in the PHEV generally exhibits higher cogging torque for its double salient structures of both stator and rotor poles. Furthermore, the back EMF wave including odd harmonics especially 3rd and 5th ones are not ideally sinusoidal that could bring some extra copper loss and decrease its efficiency. Hence, how to minimize the cogging torque so to reduce the torque ripple, and how to reduce the total harmonic distortion (THD) of the back EMF wave are important issues in the field of FSPMM. Four rotor topologies in this paper are proposed to suppress the cogging torque and make the back EMF more sinusoidal for an FSPMM with 12/14 (stator/rotor) poles so as to make it more suitable to the brushless AC (BLAC) operation. Plenty of theory analysis and quantitative comparisons are made between different schemes. The validity of the proposed techniques has been confirmed by 2-D models of the finite element algorithm (FEA) executed in commercial software, Ansoft Maxwell 12.
Xu, W, Zhu, J, Zhang, Y & Wang, T 1970, 'Electromagnetic design and performance evaluation on 75 kW axially laminated flux switching permanent magnet machine', 2011 International Conference on Electrical Machines and Systems, 2011 International Conference on Electrical Machines and Systems (ICEMS), IEEE.
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One 75 kW axially laminated flux switching permanent magnet machine (ALFSPMM) with 12/14 (stator/rotor) poles is proposed in this paper. For the stator lamination in parallel with the direction of permanent magnet flux linkage, it can make full use of permanent magnet and reduce relevant flux leakage and iron loss especially in high speed applications. Because of partly serious saturation and nonlinear trait of inductance, optimal electromagnetic design has been done to decrease the cogging torque and part saturation of flux density distributed in the tip or edge of stator tooth and rotor pole. Theoretical investigation on ALFSPMM is confirmed by plentiful simulations mainly based on two-dimensional model analyzed by finite element algorithm on the platform of commercial software Ansoft Maxwell 12. Compared with the traditional flux switching permanent magnet machine (FSPMM), ALFSPMM has stronger torque density, greater flux weakening ability, and higher efficiency. It can be regarded as one ideal candidate for the drive system of plug-in hybrid electrical vehicle (PHEV). © 2011 IEEE.
Yi Lei, Zhao, Z, Xu, W & Jianguo Zhu 1970, 'Modeling and analysis of MW-level grid-connected PV plant', IECON 2011 - 37th Annual Conference of the IEEE Industrial Electronics Society, IECON 2011 - 37th Annual Conference of IEEE Industrial Electronics, IEEE, Melbourne, VIC, pp. 890-895.
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This paper focuses on the modeling and analysis of the basic composition, characteristic and the interactions with grid for megawatt (MW)-level large scale grid-connected photovoltaic (PV) plants. For a MW-level PV plant, numbers of inverters with relatively smaller capacity are employed to operated in parallel. When the irradiance on the large area of PV array is not equal, the output power verses the voltage of the PV array will have several peak values and affect the maximal power tracking. LCL filters are adopted for filtering the harmonics generated by inverters, but due to its inherent resonance character, additional damping strategy is required. The power quantity of harmonics and voltage fluctuation may occur when one MW-level PV plant is connected to grid. For these characteristics, with the modeling and simulation of a real MW-level PV plant, this paper proposed and verified a novel method toward MPPT of large area PV arrays. The parallel running of inverters and grid voltage fluctuation are also simulated. Finally, the interaction with the grid voltage fluctuation is explored in detail.
Yongchang Zhang & Jianguo Zhu 1970, 'Direct torque control of cascaded brushless doubly fed induction generator for wind energy applications', 2011 IEEE International Electric Machines & Drives Conference (IEMDC), Drives Conference (IEMDC), IEEE, pp. 741-746.
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This paper proposes a novel configuration for wind energy applications by using a cascaded brushless doubly fed induction generator (CBDFIG) controlled by direct torque control (DTC), which eliminates the slip rings and brushes associated with the conventional DFIG and features quick response. Due to the increased complexity of CBDFIG model, prior vector control for CBDFIG is complicated and relies much on the machine parameters and controller tuning. Furthermore, so far the literature regarding CBDFIG did not address the issue of grid synchronization, which is important for reducing the impacts on both grid and CBDFIG and useful for re-closing after fault is cleared. This paper investigates the analysis and design of DTC of CBDFIG for both grid synchronization and grid connected operations without changing the switching table. The influence of additional rotor circuit is investigated and it is found that this influence is small and can be neglected. The DTC developed in this paper is very simple and achieves excellent dynamic response and steady state performance. Simulation results are presented to validate the effectiveness of the developed DTC for CBDFIG. © 2011 IEEE.
Yue Dong Zhan, You Guang Guo & Jian Guo Zhu 1970, 'Intelligent coordination steering control of automated guided vehicle', 2011 International Conference on Applied Superconductivity and Electromagnetic Devices, 2011 International Conference on Applied Superconductivity and Electromagnetic Devices (ASEMD), IEEE, Sydney, Australia, pp. 204-207.
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In this paper, based on the neural network, fuzzy control and bang-bang control, an intelligent coordination control strategy for automated guided vehicle (AGV) steering system is presented. The dynamic steering model of distance error and orientation angle error for AGV is expressed. With least square method of system identification, the model of AGV is identified. Because a toy type of AGV is employed, its structure is simple, but AGV model parameters are variable according to the operating conditions and environment. In order to improve the dynamic performances of AGV, the intelligent coordinated control strategy is used to design the AGV controller in the AGV steering control system. Simulation and experimental results show the effectiveness of the proposed control strategy.
Yue Dong Zhan, You Guang Guo & Jian Guo Zhu 1970, 'Terminal sliding mode speed controller based on vector control for brushless doubly fed machine', 2011 International Conference on Applied Superconductivity and Electromagnetic Devices, 2011 International Conference on Applied Superconductivity and Electromagnetic Devices (ASEMD), IEEE, Sydney, Australia, pp. 200-203.
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In this paper, based on the principle of rotor field oriented vector control (VC), a terminal sliding mode controller (TSMC) for brushless doubly fed machine (BDFM) adjustable speed system is presented. Because of using the fast terminal sliding mode control, the proposed controller for BDFM eliminates the average chattering encountered by most TSMC schemes, and employs the robustness and excellent dynamic performances of TSMC. Simulation results show that the proposed control strategy is of the feasibility, correctness and effectiveness.
Yun Hong Zhang, Wei Xu, Xian Yong Xiao, Ceng Bi Zeng & Jian Guo Zhu 1970, 'Speed adjustment of permanent magnet synchronous machine based on fuzzy self-adapting PI controller', 2011 International Conference on Applied Superconductivity and Electromagnetic Devices, 2011 International Conference on Applied Superconductivity and Electromagnetic Devices (ASEMD), IEEE, pp. 169-174.
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This paper presents a fuzzy self-adapting PI controller in the current loop to modify the speed response of permanent magnet synchronous machine (PMSM) based on the space vector pulse width modulation (SVPWM) technique. By the SVPWM modification, it can improve the utilization of DC voltage and reduce the torque ripple. Meanwhile, the fuzzy self-adapting PI controller can correct the parameters of PI automatically and adaptively when outer parameters are changed. Simulations indicate that the fuzzy self-adapting PI controller has better dynamic performances and greater robustness than that traditional PI controller. © 2011 IEEE.
Zhan, YD, Guo, YG & Zhu, JG 1970, 'Intelligent comprehensive control to prevent performance degradation of PEM fuel cell', 2011 International Conference on Applied Superconductivity and Electromagnetic Devices, 2011 International Conference on Applied Superconductivity and Electromagnetic Devices (ASEMD), IEEE, Sydney, Australia, pp. 196-199.
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To prevent the performance degradation of proton exchange membrane fuel cell (PEMFC), this paper conducts research in intelligent comprehensive control of the operational parameters, such as the operating temperature, pressure, mass flows of hydrogen and air for the PEMFC stack, current density, the exhaust emission quantity of reactant gas, and humidity of the hydrogen and air/oxygen. An analysis is presented about the factors which affect the performance of PEMFC stack, including the influences of the leakage loss, and internal structures of the stack. An intelligent comprehensive control strategy is proposed and applied to a 300 W PEMFC system for an uninterruptible power supply (UPS) with backup PEMFC and battery power sources. The experimental results show that the performances of PEMFC have been improved comparing with the normal performance using the conventional PI control, and performance degradation can be prevented effectively.
Zhang, Y, Li, Z, Hu, J, Xu, W & Zhu, J 1970, 'A cascaded brushless doubly fed induction generator for wind energy applications based on direct power control', 2011 International Conference on Electrical Machines and Systems, 2011 International Conference on Electrical Machines and Systems (ICEMS), IEEE, Beijing, China.
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This paper proposes a direct power control (DPC) strategy for cascaded brushless doubly fed induction generator (CBDFIG), which eliminates the slip rings and brushes in conventional DFIG wind turbine systems and features quick dynamic response and excellent steady state performance. Prior methods for controlling CBDFIG are based on vector control (VC), which is complicated and requires much tuning work and machine parameters. Appropriate decoupling and fine PI tuning are mandatory to obtain good performance over the entire operating range. Furthermore, there are few papers regarding the grid synchronization issue of CBDFIG. This paper firstly analyzes the influence of each voltage vector on active/reactive powers and then proposes a unified switching table for both grid-connected operation and grid synchronization process. The effectiveness of the developed DPC method for CBDFIG is confirmed by the presented simulation results. © 2011 IEEE.
Zhang, Y, Li, Z, Wang, T, Hu, J & Zhu, J 1970, 'Predictive direct torque and flux control of doubly fed induction generator with switching frequency reduction for wind energy applications', 2011 International Conference on Electrical Machines and Systems, 2011 International Conference on Electrical Machines and Systems (ICEMS), IEEE, Beijing, China.
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A model based predictive torque and flux control (PTFC) is proposed in this paper for doubly fed induction generator (DFIG) applied in wind energy applications. Different from the conventional switching-table-based direct torque control (DTC), which selects the output vector from a switching table, the developed PTFC selects the most suitable vector minimizing the errors of rotor flux and torque based on predictions of their evolutions versus time. Compared to DTC with the same sampling frequency, there are significant reductions in both torque and flux ripples for PTFC with lower switching frequency, while their dynamic performances are similar. Furthermore, by incorporating the frequency reduction in PTFC, the average switching frequency can be reduced up to 38.76% without affecting its performance. The results of PTFC operating at a very low switching frequency of below 550 Hz are presented, validating the capability of PTFC to satisfy the low switching frequency requirement of high power wind energy applications. Simulation results are presented to validate the effectiveness of the proposed PTFC. © 2011 IEEE.
Zhang, Y, Li, Z, Wang, T, Xu, W & Zhu, J 1970, 'Evaluation of a class of improved DTC method applied in DFIG for wind energy applications', 2011 International Conference on Electrical Machines and Systems, 2011 International Conference on Electrical Machines and Systems (ICEMS), IEEE, Beijing, China.
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Large torque ripple and variable switching frequency are the two most notable drawbacks of conventional switching table based direct torque control (DTC) for doubly fed induction generator (DFIG). By using one active vector and one null vector during one control cycle, the torque ripple can be significantly reduced while achieving almost constant switching frequency. This paper propose a very simple but effective method to obtain the duty ratio of the active vector, which is able to reduce the complexity and improve the system robustness while reducing both torque and flux ripples. Furthermore, this paper points that by appropriately arranging the sequence of active vector and null vector, the switching frequency can be further reduced and the performance is only slightly affected. This fact is useful for high power wind energy applications with restricted switching frequency. The developed method is compared with one of the prior analytical methods based on torque ripple RMS minimization and exhibits lower rotor flux ripple and better harmonic performance of stator and rotor currents. The presented simulation results obtained from a 15 kW DFIG validates its effectiveness. © 2011 IEEE.
Zhang, Y, Li, Z, Xu, W, Hu, J & Zhu, J 1970, 'Grid synchronization of DFIG using model predictive direct power control', 2011 International Conference on Electrical Machines and Systems, 2011 International Conference on Electrical Machines and Systems (ICEMS), IEEE, Beijing, China.
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This paper presents a model based predictive direct power control (MPDPC) strategy to achieve soft and fast grid synchronization of doubly fed induction generator (DFIG) applied in wind energy applications. The future behavior of active and reactive powers is predicted in MPDPC using the discrete model of DFIG and the most appropriate voltage vector is selected to minimize the errors between the reference value and feedback value of active/reactive powers. Furthermore, the PI regulator and current loop in the existing methods are eliminated, featuring low complexity. The grid connection process is very quick and smooth without any overcurrent. The developed novel MPDPC is compared with prior method based on switching-table-based DPC (STDPC) and shows quicker response, better steady state performance and lower switching frequency, which are validated by the simulation results obtained from a 15 kW DFIG system. © 2011 IEEE.
Zhang, Y, Zhu, J & Hu, J 1970, 'Model predictive direct torque control for grid synchronization of doubly fed induction generator', 2011 IEEE International Electric Machines & Drives Conference (IEMDC), Drives Conference (IEMDC), IEEE, pp. 765-770.
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A novel model predictive direct torque control (MPDTC) is proposed in this paper to achieve soft and fast grid synchronization for doubly fed induction generator (DFIG). This method is based on the direct control of a virtual torque and the rotor flux, which selects the optimal rotor voltage vector through an evaluation of a cost function. Neither PI regulator nor grid voltage measurement is needed for the MPDTC and only the information of grid voltage, rotor current and rotor position are necessary. The influence of one-step delay caused by digital implementation is also investigated in this paper. The MPDTC is compared with the switching-table-based direct torque control (STDTC) and exhibits better performance in terms of lower ripples in torque and flux, less rotor current harmonics and lower switching frequency. The presented simulation results verify the effectiveness of the novel method. © 2011 IEEE.
