Gann, P, Nghiem, L & Warner, S 1989, 'Pregnancy characteristics and outcomes of Cambodian refugees.', American Journal of Public Health, vol. 79, no. 9, pp. 1251-1257.
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This study describes the perinatal characteristics of Cambodian refugees in Massachusetts. Data were abstracted from the records of 452 consecutive pregnancies among Cambodian women and 110 low-income Whites receiving obstetrical services at the same clinic and hospital in Lowell, Massachusetts. Pregnancies of Cambodian women were marked by a higher proportion of older mothers, grand multiparas, previous adverse birth outcomes, and short interpregnancy intervals. We identified maternal anemia (29.9 percent with hemoglobin less than 110 g/L) and inadequate utilization of prenatal care (32.3 percent with first visit in the 3rd trimester) as possible risk factors for the Cambodians. The prevalence of primary cesarean birth was only 6.3 percent in the Cambodians, compared to 15.6 percent in the comparison group, largely due to the infrequent occurrence of prolonged labor among multiparas. Despite the prominence of several risk factors for adverse birth outcomes in this population, major pregnancy complications were less common and the prevalence of low birthweight (6.4 percent) was close to the state average. Logistic regression analysis of risk factors for low birthweight identified young maternal age and short stature as the strongest factors operative in this community. Many of our findings are consistent with a strong cultural emphasis on managing the size of the baby to avoid a difficult labor and delivery.
Huang, MZ & Waldron, KJ 1989, 'An Efficient Rate Allocation Algorithm in Redundant Kinematic Chains', Journal of Mechanisms, Transmissions, and Automation in Design, vol. 111, no. 4, pp. 545-554.
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This paper addresses a basic problem which arises in the coordination of serial chain manipulators, namely, that of decomposing a given end effector velocity state into a set of joint rates. Such a problem is indeterminate for manipulators with kinematic redundancy. A novel method of solving the rate distribution problem for the class of fully revolute-jointed, serial manipulators is developed. The technique is an extension of the axial field solution scheme developed initially for solving the force allocation problem in a statically indeterminate parallel chain system. The basis of the solution method lies in the dualities of velocity and force systems between series and parallel mechanisms. The method offers an efficient means of rate coordination and is especially useful in the control of manipulators with high degrees of redundancy. Two examples have been given for illustration. It is shown that the minimum norm solution, obtainable commonly from pseudoinverse, can also be achieved using this new efficient algorithm.
Huang, MZ & Waldron, KJ 1989, 'Efficient rate allocation algorithm in redundant kinematic chains', Journal of mechanisms, transmissions, and automation in design, vol. 111, no. 4, pp. 545-554.
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This paper addresses a basic problem which arises in the coordination of serial chain manipulators, namely, that of decomposing a given end effector velocity state into a set of joint rates. Such a problem is indeterminate for manipulators with kinematic redundancy. A novel method of solving the rate distribution problem for the class of fully revolute-jointed, serial manipulators is developed. The technique is an extension of the axial field solution scheme developed initially for solving the force allocation problem in a statically indeterminate parallel chain system. The basis of the solution method lies in the dualities of velocity and force systems between series and parallel mechanisms.
Kumar, VR & Waldron, KJ 1989, 'Adaptive gait control for a walking robot', Journal of Robotic Systems, vol. 6, no. 1, pp. 49-76.
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Kwan, PYK & Shannon, AG 1989, 'Objective tests and latent trait theories', International Journal of Mathematical Education in Science and Technology, vol. 20, no. 3, pp. 457-467.
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After a discussion about objectivity in measurement, this paper describes some linear and logistic models for the implementation of latent trait theory. The aim is to consider those mathematical and educational issues pertinent to learning more about the topic and using those standardized tests which utilize the Rasch and similar models of assessment. © 1989 Taylor and Francis Group, LLC.
Sheng, D, Knutsson, S & Axelsson, K 1989, 'Verification and application of a numerical model for frost front penetration', Frost in geotechnical engineering. International symposium, Saariselka, 1989. Vol. 1, pp. 401-414.
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A PC-version of a numerical model for calculation of the frost front penetration and the temperature distribution in frozen and unfrozen soils has been developed. The model is described and so are the results from the application of the model to a field test. -from Authors
Stewart, MG & Melchers, RE 1989, 'Checking Models in Structural Design', Journal of Structural Engineering, vol. 115, no. 6, pp. 1309-1324.
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A large proportion of structural failures are due to human error in the design stage of a structural engineering project and many of these failures could have been averted if there had been adequate design checking Results are reported herein from surveys investigating the effectiveness of three typical design-checking processes: self-checking independent detailed design checking and overview checking Following a review of current work in this area appropriate mathematical models which examine the effects of error magnitude time and experience are proposed for each design checking process These are compared to the limited data obtained from the surveys Although preliminary the results have interesting implications for practitioners. © ASCE.
Stewart, MG & Melchers, RE 1989, 'Decision model for overview checking of engineering designs', International Journal of Industrial Ergonomics, vol. 4, no. 1, pp. 19-27.
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Overview checking occurs whenever an engineering design is reviewed by another engineer without specifically carrying out checking calculations or following through the design process in detail. Results are reported herein of a survey examining the effectiveness of overview checking. The respondents were requested to assess whether a structural design should be considered 'undersized', 'correct' or 'oversized'. Using the responses as a basis, a decision model is proposed for the effectiveness of overview checking as a function of error magnitude and of checker's experience. It is concluded that correct assessment of a design as 'safe' is not a function of experience. However, it appears that more experience is beneficial in selecting economical designs. © 1989.
Stewart, MG & Melchers, RE 1989, 'Error control in member design', Structural Safety, vol. 6, no. 1, pp. 11-24.
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Available evidence suggests that design checking can significantly reduce the incidence of structural failures resulting from human errors in the design process. Since 'real-world' experimentation is not possible, it is of interest to develop a model to simulate the effects of human error on a typical design task and also to model typical checking procedures. The development and analysis of these models is described in the present paper. The design task considered is that of member design for a rafter of a steel portal frame building. It was found that checking efficiencies between 0.6 and 0.9 are most effective in increasing structural reliability and that, often, only two separate design checks are necessary to virtually eliminate the incidence of structural failure due to human error. © 1989.
Stewart, MG & Melchers, RE 1989, 'Optimization of Structural Design Checking', Journal of Structural Engineering, vol. 115, no. 10, pp. 2448-2460.
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It is generally acknowledged that design checking reduces the incidence of structural failure. Because checking is often seen as nonproductive and costs money, the optimal degree of design checking is of interest. In the present paper, a decision model is developed to determine the optimal level of design checking. It is applied to the design of a steel rafter for a portal frame building. The model incorporates the effect of either an insured or an uninsured designer. Optimization was achieved by maximizing the expected utility. Using the model, it was found that the use of thorough self-checking and overview checking only is the optimal strategy, unless the consequences of failure are expected to be catastrophic, in which case one independent “design check” is also necessary. © ASCE.
Stewart, MG & Melchers, RE 1989, 'Structural design and design checking', Civil engineering transactions, vol. CE31, no. 1, pp. 63-69.
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The process of structural design has received very little attention from the research community despite its centralness in day-to-day structural engineering. Much of the research which has been done has been carried out in Australia over a number of years and with the co-operation of many structural engineers. The present paper reviews the reasons for being engaged in this relatively unusual research activity and provides an overview of the work to date. A review is given of the incidence and type of errors made in basic design tasks such as calculations, table look-up and table interpolation, and how these errors relate to results obtained for more comprehensive tasks such as loading determination and member design. One of the outcomes of the work has been to suggest areas in certain current design codes which are prone to misinterpretation by practitioners. Preliminary results related to design computation checking and inspection are also reviewed. This work potentially has major implications for quality assurance programmes.
Visvanathan, C, Aim, RB & Vigneswaran, S 1989, 'Application of cross-flow electro-microfiltration in chromium wastewater treatment', Desalination, vol. 71, no. 3, pp. 265-276.
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Cross-flow microfiltration (CFMF) was experimentally studied for the separation of precipitates of chromium hydroxide. Although this process enables one to obtain chromium-free filtrate, a disadvantage is that the filtration flux declines rapidly due to membrane fouling. In order to avoid this fouling problem and increase the filtration flux, an electric field was applied across the membrane as an antifouling technique (cross-flow electro-microfiltration-CFEMF). The surface charges of the precipitates were modified by adding a dispersant. The experimental results indicate that this modified process of CFEMF is highly effective in reducing the membrane fouling, which eventually leads to a remarkable filtration flux increase. The application of this antifouling technique of CFEMF is cited only for the suspensions containing charged particles and colloids. Nevertheless, the process of modification of surface charge with a dispersant permits us to use this technique with a wide variety of suspensions. © 1989.
Watterson, PA 1989, 'Child-Langmuir sheath structure around wedge-shaped cathodes', Journal of Physics D: Applied Physics, vol. 22, no. 9, pp. 1300-1307.
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The steady state Child-Langmuir sheath around a wedge-shaped cathode immersed in a plasma is calculated numerically. The ions drawn from the plasma may be employed to sputter material from the cathode, or may implant into the cathode, depending upon the magnitude of the applied negative voltage. The ion impact rate onto the cathode reaches 2.2 times higher near a square edge and 3.6 times higher near a knife edge than the rate for planar surfaces of the cathode. However, for a knife edge the rate falls to zero at the edge. All the ions strike the cathode with the same kinetic energy, but the angle of impact is nonperpendicular near the edge, which could reduce the implantation depth and increase sputtering. © 1989 IOP Publishing Ltd.
Young, W, Hadgraft, R, Friday, R, Prior, M, Sharpe, R, Spencer, WJ, Szwed, N, Taylor, MAP, Walker, D & Wigan, M 1989, 'Knowledge based systems in civil engineering', Civil Engineering Systems, vol. 6, no. 1-2, pp. 3-4.
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Zamorano, LJ, Martinez-Coll, A & Dujovny, M 1989, 'Transposition of Image-defined Trajectories into Arc-quadrant Centered Stereotactic Systems', pp. 109-111.
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BALL, JE, OLOUGHLIN, GG & COUNCIL, AWR 1970, 'APPROPRIATE MODELS FOR URBAN STORM-SEWER SYSTEMS', WATERCOMP 89, 1ST AUSTRALASIAN CONF ON TECHNICAL COMPUTING IN THE WATER INDUSTRY ( PREPRINTS ), INST ENGINEERS AUSTRALIA, MELBOURNE, AUSTRALIA, pp. 131-135.
Braun, RM 1970, 'Multi-dimensional median filtering for processing network and spectrum analyzer information', pp. 85-89.
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The author describes the use of median filtering to enhance the readability of the trace information of such instruments as network analyzers and spectrum analyzers. A class of mildly recursive median filters (MRMFs) is described, and application to a spectrum analyzer is demonstrated. The results show that a 41% improvement in Gaussian noise, using an MRMF with a window size of three samples, is possible. The MRMF turns out to have considerably better performance for very small window sizes than nonrecursive MFs.
Dujovny, M, Martinez-Coll, A, Ausman, JI, Perlin, A & Stewart, M 1970, 'Intracranial pressure correlation with cytochrome aa3 and hemoglobin redox measured by noninvasive near infrared spectrophotometry', Surgical Forum, pp. 478-479.
HADGRAFT, RG & WIGAN, MR 1970, 'A POSSIBLE PROTOTYPE FOR A NEW AUSTRALIAN RAINFALL AND RUNOFF', HYDROLOGY AND WATER RESOURCES SYMPOSIUM 1989 : COMPARISONS IN AUSTRAL HYDROLOGY, 18TH SYMP ON HYDROLOGY AND WATER RESOURCES : COMPARISONS IN AUSTRAL HYDROLOGY ( PREPRINTS ), INST ENGINEERS AUSTRALIA, UNIV CANTERBURY, CHRISTCHURCH, NEW ZEALAND, pp. 481-482.
HADGRAFT, RG & WIGAN, MR 1970, 'ASSESSMENT AND IMPROVEMENT OF THE CODIFICATION AND DELIVERY OF ENGINEERING EXPERIENCE', WATERCOMP 89, 1ST AUSTRALASIAN CONF ON TECHNICAL COMPUTING IN THE WATER INDUSTRY ( PREPRINTS ), INST ENGINEERS AUSTRALIA, MELBOURNE, AUSTRALIA, pp. 160-164.
HADGRAFT, RG & WIGAN, MR 1970, 'TOWARDS EFFECTIVE FIELD SUPPORT AND RETRAINING FOR ENGINEERS WHO USE AUSTRALIAN RAINFALL AND RUNOFF', HYDROLOGY AND WATER RESOURCES SYMPOSIUM 1989 : COMPARISONS IN AUSTRAL HYDROLOGY, 18TH SYMP ON HYDROLOGY AND WATER RESOURCES : COMPARISONS IN AUSTRAL HYDROLOGY ( PREPRINTS ), INST ENGINEERS AUSTRALIA, UNIV CANTERBURY, CHRISTCHURCH, NEW ZEALAND, pp. 468-472.
Stauffer, LA & Slaughterbeck-Hyde, RA 1970, 'The Nature of Constraints and Their Effect on Quality and Satisficing', 1st International Conference on Design Theory and Methodology, ASME 1989 Design Technical Conferences, American Society of Mechanical Engineers.
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Abstract
A taxonomy of constraints is presented based on design considerations, source, context, strength, and use. The taxonomy is developed from observations of two sets of real-time protocol data of mechanical designers, along with the work of other researchers. The taxonomy begins to explain the nature of constraints. A hypothesis of how introduced constraints affect design quality is also presented. Finally, a more specific definition of satisficing is developed based on an experiment demonstrating constraint satisfaction.
