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Site-Specific Crop Management (SSCM) involves use of automated seeders and chemical applicators to make spatially-variable applications to agricultural fields. Soil productivity is spatially variable and thus, SSCM provides an opportunity to reduce total applications of seed and fertilizer without reducing crop yields. Also, more complete crop use of fertilizers with SSCM could reduce the potential for environmental contamination. A key element in SSCM is a Field Information System (FIS) for preparing application maps to control application rates.

This paper describes a practical and efficient approach for determining complete transient, as well as steady state response of tractor-trailer air brake systems by recording pushrod displacement and air brake service line pressure as a function to time. The test hardware utilizes easy to fabricate “clip on” transducers to measure pushrod stroke length. Data acquisition is via LABVIEW‚. All transducers are easy to temporarily affix to any tractor- trailer and require no alteration to the vehicle. A complete system check takes less time than manually measuring pushrod stroke as required under FMCSA. This system with one treadle application and release gives digital timing and displacement history of all brakes. Useful information includes: application and release profiles (pushrod velocity), shoe compliance upon seating and crack pressure release points for both tractor and trailer relay valves.

Low aspect ratio wings are used extensively on open-wheeled race cars to generate aerodynamic downforce. Consequently, a great deal of effort is invested in obtaining wing profiles that provide high values of lift coefficient. If the wings are designed using 2-D methods, then it is necessary to take into account the change in operating angle of a typical airfoil section that occurs when it operates in the downwash generated by the wing. Accounting for this change during the design phase will ensure that the airfoil sections are optimized for their intended operating conditions. The addition of endplates to the wing serves to counteract the magnitude of the change in operating angle by effectively producing an increase in wing aspect ratio. During the design process at UIUC, an empirical method was used to provide an estimate of the effective aspect ratio of the wing and endplate combination.

The development of automated guidance for agricultural tractors has addressed several basic and applied issues of agricultural equipment automation. Basic analyses have included the dynamics of steering systems and posture sensors for guidance. Applied issues have evaluated the potential of several commercial sensing systems and a commercial mechanical guidance system. A research platform has been developed based on a Case 7220 Magnum1 2-wheel drive agricultural tractor. An electrohydraulic steering system was used and characterized in support of automated guidance control. Posture sensing methods were developed using GPS, geomagnetic direction sensors (GDS), inertial, and machine vision sensing systems. Sensor fusion of GPS-inertial-machine vision and GPS-GDS-machine vision provided the most flexible and accurate guidance and capable for operation under dynamically changing field conditions.

Cavitation plays a significant role in the spray characteristics and the subsequent mixing and combustion process in engines. Cavitation has beneficial effects on the development of the fuel sprays by improving injection velocity and promoting primary break-up. On the other hand, intense pressure peaks induced by the vapor collapse may lead to erosion damage and severe degradation of the injector performance. In the present paper, the transient cavitating flow in the injector-like geometry was investigated using the modified turbulence model and cavitation criterion. A local density correction was used in the Reynolds-averaged Navier-Stokes turbulence model to reduce the turbulent viscosity, which facilitates the cavitation development. The turbulent stress was also considered in the cavitation inception stage. The modified model is capable of reproducing the cavitating flow with an affordable computational cost.

The availability and low price of personal computers with suitable interface equipment has made it practical to use such a system for cylinder pressure data acquisition. With this objective, procedures have been developed to measure and record cylinder pressure on an individual crank angle basis and obtain an average cylinder pressure trace using an Apple II Plus personal computer. These procedures as well as methods for checking the quality of cylinder pressure data are described. A simplified heat release analysis technique for an approximate first look at the data quality is presented. Comparisons are made between the result of this analysis, the Krieger-Borman heat release analysis which uses complete chemical equilibrium. The comparison is made to show the suitability of the simplified analysis in judging the quality of the pressure data.

A prediction model for hand prehensile movements was developed and validated. The model is based on a new approach that blends forward dynamics and a simple parametric control scheme. In the development phase, model parameters were first estimated using a set of hand grasping movement data, and then statistically analyzed. In the validation phase, the model was applied to novel conditions created by varying the subject group and size of the object grasped. The model performance was evaluated by the prediction errors under various novel conditions as compared to the benchmark values with no extrapolation. Analyses of the model parameters led to insights into human movement production and control. The resulting model also offers computational simplicity and efficiency, a much desired attribute for digital applications.

An experimental study was performed at the University of Illinois at Urbana-Champaign Low-Speed Wind Tunnel to quantify the performance and flowfield effects of two-element open-wheel-race-car front wing configurations. Four distinct configurations were tested in- and out-of-ground effect and at various speeds (Reynolds numbers), angles of attack, and flap positions. A splitter plate was installed in the wind tunnel to act as the ground plane. Data presented include balance force measurements, surface pressure data, and downstream flow measurements using a seven-hole probe. Results show that these elementary factors in the design of race-car front wings have a significant effect on wing performance and behavior of the downstream flowfield.

This paper examines the feasibility of modifying an existing semi-trailer air suspension system to function as an anti-rollover system in addition to its normal suspension operation. The semi-trailer model used is a dynamic, two-dimensional system. The anti-rollover system controller is formulated using projective control theory. All other factors being equal, simulations show that use of the modified suspension system decreases the weight shift when the semi-trailer undergoes lateral acceleration. By decreasing weight shift, the modified suspension system decreases the possibility of rollover.

Environmental concerns have obstructed development of new landfill sites making it essential to efficiently use currently available space. Finite element methods are evaluated for predicting densification by compactors with the intent of eventually optimizing vehicle design with respect to compaction. A geometrically non-linear, plane strain, quasistatic analysis is used to capture the effects of a single rigid wheel. Future work will include multiple wheels and successive passes, three-dimensional simulations, and realistic material characterization.

Cyclic loading is not as damaging as static loading of ceramics at high temperatures. Microcrack growth retardation has been established as a mechanism for increasing the durability of ceramics at high temperatures. A combined experimental and theoretical approach provides a mechanistic understanding of the deformation and failure processes in ceramic materials at high temperatures. Results demonstrate that the high temperature behavior of some ceramic material systems are controlled by the behavior of the grain boundary phase whose response is considerably different under static and cyclic loading.

Past research on airfoil and wing aerodynamics in icing are reviewed. This review emphasizes the periods after the 1978 NASA Lewis workshop that initiated the modern icing research program at NASA and the current period after the 1994 ATR accident where aerodynamics research has been more aircraft safety focused. Research pre-1978 is also briefly reviewed. Following this review, our current knowledge of iced airfoil aerodynamics is presented from a flowfield-physics perspective. This section identifies four classes of ice accretions: roughness, rime ice, horn ice, and spanwise ridge ice. In these sections the key flowfield features such as flowfield separation and reattachment are reviewed and how these contribute to the known aerodynamic effects of these ice shapes. Finally Reynolds number and Mach number effects on iced-airfoil aerodynamics are briefly summarized.

This paper presents an experimental analysis of the performance of various control strategies applied to automotive air conditioning systems. A comparison of the performance of a thermal expansion valve (TEV) and an electronic expansion valve (EEV) over a vehicle drive cycle is presented. Improved superheat regulation and minor efficiency improvements are shown for the EEV control strategies. The efficiency benefits of continuous versus cycled compressor operation are presented, and a discussion of significant improvements in energy efficiency using compressor control is provided. Dual PID loops are shown to control evaporator outlet pressure while regulating superheat. The introduction of a static decoupler is shown to improve the performance of the dual PID loop controller. These control strategies allow for system capacity control, enabling continuous operation and achieving significant energy efficiency improvements.

High strength materials have desirable mechanical properties but often cannot be machined economically, which results in unacceptably high finished component cost. MADI™ (machinable austempered ductile iron) overcomes this difficultly and provides the highly desirable combination of high strength, excellent low temperature toughness, good machinability and attractive finished component cost. The Machine Tool Systems Research Laboratory at the University of Illinois at Urbana-Champaign performed extensive machinability testing and determined the appropriate tools, speeds and feeds for milling and drilling (https://netfiles.uiuc.edu/malkewcz/www/MADI.htm). This paper provides the information necessary for the efficient and economical machining of MADI™ and provides comparative machinability data for common grades of ductile iron (EN-GJS-400-18, 400-15, 450-10, 500-7, 600-3 & 700-2) for comparison.

Techniques developed for structural reliability analysis are applied to mechanical reliability problems, including those with non-normal random variables, complicated design equations, chain and ductile system structures, and screening or testing of components.

This paper describes and discusses a computer model that can be used to predict the hydraulic pump requirements of an excavator necessary to meet the specified productivity levels for a given set of design conditions. The model predicts the hydraulic cylinder flow rates, pressures, and power necessary to sustain a given work cycle. The study compares the results from a simulation of the excavator with actual test data obtained from a test vehicle taken during a typical work cycle.

High costs and extreme risks prevent the life testing of NASA hardware. These unavoidable limitations prevent the determination of sound reliability bounds for NASA hardware; thus the true risk assumed in future missions is unclear. A simulation infrastructure for determining these risks is developed in a configurable format here. Positive preliminary results in preparation for validation testing are reported. A stochastic filter simulates non-deterministic output from the various unit processes. A maintenance and repair module has been implemented with several levels of complexity. Two life testing approaches have been proposed for use in future model validation.

Neural networks are massively parallel computational models for knowledge representation and information processing. The capabilities of neural networks, namely learning, noise tolerance, adaptivity, and parallel structure make them good candidates for application to a wide range of engineering problems including diagnostics problems. The general approach in developing neural network based diagnostic methods is described through a case study. The development of an acoustic wayside train inspection system using neural networks is described. The study is aimed at developing a neural network based method for detection defective wheels from acoustic measurements. The actual signals recorded when a train passes a wayside station are used to develop a neural network based wheel defect detector and to study its performance. Signal averaging and scoring techniques are developed to improve the performance of the constructed neural inspection system.

The type of differential used in a vehicle has an important and often-neglected effect on handling performance. This is particularly important in racing applications, such as in IndyCar racing, in which the type of differential chosen depends on the course being raced (superspeedway ovals, short ovals, temporary street courses and permanent road courses). In the present work, we examine the effect of a locked rear differential on oversteer/understeer behavior. Using a linear tire model, it is shown that employing a locked differential adds a constant understeer offset to the steering wheel angle (SWA) -v- lateral acceleration vehicle signature. A computer simulation of steady-state cornering behavior showed that the actual effect is much more complicated, and is strongly influenced by static weight distribution, front/rear roll couple distribution, available traction and the radius of the turn being negotiated.

Control system design is one of the most critical issues for implementation of intelligent vehicle systems. Wide ranged fundamental research has been undertaken in this area and the safety issues of the fully automated vehicles are clearly recognized. Study of vehicle performance constrains is essential for a good understanding of this problem. This paper discusses safety issues of heavy-duty vehicles under automatic steering control. It focuses on the analysis of the effect of tire force saturation. Vehicle handling characteristics are also analyzed to improve understanding of the truck dynamics and control tasks. A simple differential brake control is formulated to show its effect of on reducing trailer swing.