Academic literature on the topic 'LD5655.V851 1991.K758'

In this research effort, we consider the linear complementarity problem (LCP) that arises in diverse areas including optimal control, economics, engineering, mechanics, and quadratic programming. This class of problems has posed a challenge to researchers for over three decades now. Most of the current algorithms designed to solve LCP are guaranteed to work only under some restrictive assumptions on the matrix <i>M</i> associated with LCP. In this research, we introduce two new algorithms based on an equivalent 0-1 mixed integer bilinear programming formulation of LCP. In the first approach, we develop an enhanced intersection cutting plane algorithm for solving LCP. The matrix <i>M</i> is not assumed to possess any special structure, except that the corresponding feasible region is assumed to be bounded. A procedure is described to generate cuts that are deeper versions of Tuy's intersection cuts, based on a relaxation of the usual polar set. The proposed algorithm then attempts to find an LCP solution in the process of generating either a single or a pair of such strengthened intersection cuts. The process of generating these cuts involves a vertex ranking scheme that either finds an LCP solution, or else, these cuts eliminate the entire feasible region leading to the conclusion that no LCP solution exists. Based on the bilinear formulation, a heuristic is also proposed to front-end the algorithm, in order to possibly solve LCP. In the second part of the dissertation, we present a global optimization algorithm based on a novel Reformulation-Linearization Technique (RLT). We do not place any restrictions on the matrix M associated with LCP in this case. This RLT scheme provides an equivalent linear, mixed integer programming formulation of LCP, that possesses a tight linear programming relaxation. The solution strategy developed is a composite impliCit enumeration-Lagrangian relaxation scheme. In addition to the bounds provided by the RLT-based relaxation, we further tighten these bounds at each node of the branch-and-bound tree through the use of strongest surrogate cuts, and strengthened intersection cuts. The heuristic developed in the previous algorithm is also invoked within this scheme. Both algorithms have been implemented and tested on randomly generated test problems. These problems include both indefinite and negative definite defining matrices. The results of these tests indicate that both methods are effective in solving the LCP with the heuristic being quite effective in recovering LCP solutions when the matrix Mis negative definite. The Lagrangian dual approach for the implicit enumeration scheme proved to be computationally more efficient than a similar simplex based lower bounding scheme.<br>Ph. D.

<p>This research investigated the effect of mouse support height, mouse type, and hand length on the wrist posture of computer mouse operators. Mouse support height was defined as the distance from the floor to the horizontal surface on which the mouse is supported and divided into three levels: 95%, 100%, and 105% of the seated elbow height. The levels of mouse type were the Logitech MouseMan, Kensington Thinking Mouse, Apple Desktop Bus Mouse, and the Apple Desktop Bus Mouse II. Hand size was defined as the distance from the stylion landmark on the right hand to the tip of the middle finger. The twenty-four subjects were divided into three groups of eight according to hand size (small, medium, and large).</p> <p> The average distance in degrees from neutral was calculated for the first set of dependent measures. Results showed that an increase in the mouse support height caused a decrease in the amount of wrist extension and an increase in the amount of ulnar deviation for both pointing and dragging tasks. There was also a significant interaction between mouse support height and hand size for wrist extension during pointing tasks.</p> <p> Mouse type and hand size were not found to be significant as main effects in either pointing or dragging tasks. It was probable that the differences in the physical characteristics of either the userfs hands or of the mice were not great enough to affect the posture of the user.</p> <p>For the second set of dependent measures, wrist posture was divided into intervals that ret1ect the severity of posture. Mouse support height was found to significantly affect the amount of time spent in different posture intervals. The remaining independent variables did not significantly effect these dependent measures.</p><br>Master of Science

Industrial toxicity has become a major environmental subject over the past decade. Although much research and data have been collected and published for the manufacturing type industries, minimal data is currently available concerning the possible toxics that may be associated with coal mining industry NPDES discharges. Thus, in this report, an environmental toxicity assessment with respective data shall be presented on the three major constituent sectors of the coal mining industry in Southwest Virginia of which includes mines, preparation plants and refuse facilities. The mines category shall include both surface and underground facilities. The preparation plants sector will cover the traditional railroad siding loadout type facilities, along with the modern clean coal processing preparation plants. Valley and side fill configuration, coarse and combined refuse fills and coal refuse impoundments shall be presented in the refuse facility categorization. Reference source data and specific information from a Virginia Coal Association Taxies Monitoring Program study are presented to show that the effects of toxicity in the coal mining associated NPDES effluents are minimal and not a serious problem. The conclusions of this report shall show that through enforcement of better management practices within the coal industry in Southwest Virginia that toxicity can be virtually eliminated in NPDES outfalls.<br>Master of Science

Several methods have been developed to determine the cyclic oligomer content in PET. Isolation procedures can be classified as those involving extraction, such as with solvents like chloroform, dioxane, and xylene, and those involving dissolution followed by precipitation in solvents like dimethylformamide and 1-methylnaphthalene. The amount of cyclic oligomer obtained is largely dependent upon the method used, as well as the type, drawing, and thermal history of the PET used.Various methods for separation of cyclic oligomers have also been developed using GPC and thin-layer chromatography.<br>Master of Science