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This paper illustrates the application of the generalized immittance space approach to the analysis of multi-bus interconnected power electronics based power distribution system. The paper sets forth the basic classifications of power converters in regard to stability analysis, a set of network reduction transformations, and illustrates the use of these reductions in order to analyze the stability of a zonal dc distribution system.

Power electronics based power distribution systems are inherently nonlinear often behaving as constant power loads. Stability analysis of such systems typically is limited to local behavior. Herein polytopic modeling techniques are presented. Classification of polytopic model equilibrium points is made and methods of determining uniform asymptotic stability are presented.

Design optimization for functionality, and manufacturability was virtually impossible in the past. However, recent standardization of file storing formats resulted in seamless data transfer from one software package to another; thus, allowing integration of all facets of product design optimization. This paper describes a metalcasting design optimization process. It focuses on the design of cast parts according to functional requirements while optimizing shape with respect to structural integrity, while ascertaining that the part can be manufactured (cast) without defects.

A methodology for modeling elastomeric mounts as nonlinear lumped parameter models is discussed. A key feature of this methodology is that it integrates dynamic test results under different conditions into the model. The first step is to model the mount as a linear model that is simple but reproduces accurately results from dynamic tests under small excitations. Frequency Response Functions (FRF) enables systematic calculation of the parameters for the model. Under more realistic excitation, the mount exhibits non-linearity, which is investigated in the next step. For nonlinear structures, a simple and intuitive method is to use time-domain force-displacement (F-x) curves. Experiments to obtain the F-x curves involve controlling the displacement excitation and measuring the induced forces. From the F-x curves, stiffness and damping parameters are obtained with an optimization technique.

A procedure for simulating the dynamics of agricultural and forestry machines using mechanical system simulation software is presented. A soil/track interface model including rubber-track and steel-track was introduced as well as equations that can be used to model mechanical and hydraulic power trains commonly found in tracked vehicles. Two rubber-tracked vehicles (agricultural tractors) and two steel-tracked machines (forestry vehicles) were simulated to illustrate the technique, and some analysis results are presented. The examples given in this paper are based on the author’s research over the past several years.

Throughout the industry, organizations struggle with the task of implementing effective human factors programs aimed at reducing maintenance errors. Almost universally, many barriers have frustrated these efforts. In 1998 and 1999, the National Transportation Safety Board sponsored two workshops designed at identifying barriers to the implementation of human factors programs and to explore what was working and what was not working among the many industry efforts. This paper explores the findings of these workshops. In addition, it will report findings of Purdue University studies that reveal a rapid deterioration of even the most successful human factors programs. The research findings disclose several “disconnects” within most organizations which rapidly negate the positive effects of successful human factors and error management training and nullify many proactive human factors programs.

Recognizing that technicians and managers need additional skills in order to compete for and successfully fill management positions, a major air carrier requested that Purdue University perform a study with employees in order to identify specific skills that are required to perform successfully in leadership positions. The study identified three core competencies (leadership, communication, and management processes) needed to be a successful leader in a major air carrier environment and outlined several related knowledge and skills within each area. Currently, many individuals in front line and mid-level management are lacking in several of these knowledge bases and skill sets. Consequently, the value of addressing current deficiencies through educational and experiential learning opportunities was proposed.

Spherical beamforming was used to visualize sound radiation during a vehicle passby test. Forward and backward propagation procedures are compared in terms of computational expense. A spherical spreading correction factor is described, along with a maximum liklihood procedure for obtaining an optimal array weighting dependent on the relative distance between the microphones and the focus point. The de-Dopplerized microphone outputs are multiplied by the weighting factors and summed to yield the source strengths over a reconstruction plane “attached” to the vehicle. Results obtained using a 16 element sparse array during an actual passby are used to demonstrate the present approach.

An overview of model development for seated occupants is presented. Two approaches have been investigated for modeling the vertical response of a seated dummy: finite element and simplified mass-spring-damper methods. The construction and implementation of these models are described, and the various successes and drawbacks of each modeling approach are discussed. To evaluate the performance of the models, emphasis was also placed on producing accurate, repeatable measurements of the static and dynamic characteristics of a seated dummy.

This paper explores the current status of error management strategies and human factors efforts within regional airlines. It briefly addresses the potential needs of the environment from a perspective of the market’s accident and incident history as well as anecdotal reports received from members of the regional airline community. It also raises questions concerning the applicability of human factors and error management strategies developed in other segments of aviation to the problems faced within regional airline environments.

This paper explores the need for human factors and error management within the context of the general and corporate aviation environments. It discusses strategies currently employed in other segments of the aviation industry and how they might be utilized in the corporate and general aviation arenas. It also relates research findings and program successes experienced within the airline industry and makes recommendations as to how a consortial effort by industry organizations might be utilized to employ these strategies in corporate and general aviation operations.

This paper describes research to analyze widespread fatigue damage in lap joints. The particular objective is to determine when large numbers of small cracks could degrade the joint strength to an unacceptable level. A deterministic model is described to compute fatigue crack growth and residual strength of riveted panels that contain multiple cracks. Fatigue crack growth tests conducted to evaluate the predictive model are summarized, and indicate good agreement between experimental and numerical results. Monte Carlo simulations are then performed to determine the influence of statistical variability on various analysis parameters.

The negative consequences of unsafe behaviors on the job heavily contribute to the rising costs of doing business in terms of both organization dollars and diminished human quality of life. Developing a safety culture provides a positive proactive approach toward creating a working environment where safety is a top priority. An integral part of accomplishing this task is directly related to training individuals on how the interactions that occur among organizational members and the messages their behaviors send influence others' behaviors. This can be best addressed through communication skill development initiatives including mutual responsibility, trust, avoiding punitive strategies and facilitating assertiveness.

Results of computations of flows, sprays and combustion performed in an optically- accessible Diesel engine are presented. These computed results are compared with measured values of chamber pressure, liquid penetration, and soot distribution, deduced from flame luminosity photographs obtained in the engine at Sandia National Laboratories and reported in the literature. The computations were performed for two operating conditions representing low load and high load conditions as reported in the experimental work. The computed and measured peak pressures agree within 5% for both the low load and the high load conditions. The heat release rates derived from the computations are consistent with expectations for Diesel combustion with a premixed phase of heat release and then a diffusion phase. The computed soot distribution shows noticeable differences from the measured one.

Numerical computations of combusting transient jets are performed under diesel-like conditions. Discussions of the structure of such jets are presented from global and detailed points of view. From a global point of view, we show that the computed flame heights agree with deductions from theory and that integrated soot mass and heat release rates are consistent with expected trends. We present results of several paramaters which characterise the details of the jet structure. These are fuel mass fractions, temperature, heat release rates, soot and NO. Some of these parameters are compared with the structure of a combusting diesel spray as deduced from measurements and reported in the literature. The heat release rate contours show that the region of chemical reactions is confined to a thin sheet as expected for a diffusion flame. The soot contour plots appear to agree qualitatively with the experimental observations.

AN INTERDISCIPLINARY TEAM from Purdue University is developing a comprehensive set of educational materials for agricultural safety and health for OSHA, of the U. S. Department of Labor. The team from the Purdue school of Agriculture, school of Veterinary Medicine, and the school of Humanities, Social Science and Education are working for a year and a half to gather and catalog all existing safety materials, and to produce new ones to meet nationwide needs. The project was begun on July 1, 1974 and is scheduled to be completed by December 31, 1975. The project team includes John B. Liljedahl, professor of agricultural engineering, project leader; Avery H. Gray, assistant department head, 4-H and Youth; William H. Hamilton, agricultural education; David H. Loewer, Extension agricultural engineer; David L. Matthew, Extension Entomologist; Vernon B. Mayrose, Extension animal scientist; Ken Weinland, Extension veterinarian; Bruce A. McKenzie, Extension agricultural engineer; James L.

An experimental-analytic method of determining the stress distribution in narrow faced spur gear teeth is presented. The successful application of photostress to this contact problem is reported. It utilizes a digital computer routine developed for separating stresses in any general two-dimensional region. Results for two pairs of gears are presented. Comparison is made with values predicted by the modified Lewis formula, the Kelley and Pedersen equation, and by the Belajef solution of the Hertz contact problem for two cylinders.