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The Armed Services Vocational Aptitude Battery (ASVAB) is a test that approximately 700,000 students in 12,000 high schools take each year to determine military occupation placement. Form Assembly for the ASVAB refers to the selection of 20-35 questions, known as items, from an item pool of approximately 300 items to create a paper and pencil test in one of its ten topics. Previous research formulates form assembly as an Integer Linear Program (ILP). The current ASVAB mostly uses a Computer Adaptive Test (CAT), which estimates an examinee's ability after the examinee answers each item and selects the next item based on prior performance. The current CAT-ASVAB implementation does not control the number of items selected from each subject (taxonomy group) for a test. This thesis introduces ILPs, previously used for form assembly, that impose taxonomy restrictions and applies them to the CAT-ASVAB. We create four ILP variations and test them against the current method of item selection, by simulating 3,500 examinees (500 examinees each for seven given ability levels). The results show that all of the ILPs have acceptable solution times for CAT use, and taxonomy restrictions can be imposed while also having more even exposure rates (the number of times an item is administered divided by the number of examinees) than the current implementation of the CAT-ASVAB. A variation that relaxes most of the binary variables and constrains the difficulty of each item to be within a predetermined magnitude of the current ability estimate, performs the best in terms of item exposure (for both under and over-utilized items) and error between an examinee's estimated ability level and actual ability level. / Defense Manpower Data Center author (civilian).

Typescript, etc. / Digitized by Kansas Correctional Industries

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Bibliography: leaves 77-79. Uses computer-aided design to improve the design of a partially parallel stump jump mechanism which was initially developed by Riley. Principle aim was to reduce the existing link dimensions of the mechanism so that it can be suitable for use on small tractors.

The compressive behavior of continuous fiber composites is not as well understood as their tensile behavior because research and industrial applications have until recently focused on the latter. Furthermore, most theoretical and experimental studies on the compression of composites have examined the case of unidirectional specimens with fibers along the loading direction (0�� fibers). While this is a logical approach since it isolates the failure mode specific to this geometry (kinking), the study of multidirectional laminates is essential because these are used in all practical applications. Few theories model the compressive behavior of multidirectional laminates. None of the theories account for the stress field or the sequence and interaction of the various observed failure modes (kinking, delamination, matrix failure) specific to the multidirectional configuration. The principal objective of this investigation is to construct a realistic theory to model the compressive behavior of multidirectional composites. Compression experiments have repeatedly shown that the initial failure mode was in-plane kinking of 0�� fibers initiated at the edges of the specimens. We decided to base our compressive failure theory upon interlaminar stresses because in multidirectional laminates these are known to exist in a boundary layer along the edges. This required development of an analytical theory giving the amplitude of these stresses at the free edges. We then incorporated these stresses into a new general microbuckling equation for 0�� fibers. The global laminate failure strain was determined through several fiber and matrix failure criteria. Theoretical predictions were compared with experimental results obtained from compression testing of graphite/thermoplastic laminates with the same ply sequence but different off-axis ply angles. The theory correlated well with experiments and confirmed that in-plane kinking was the critical failure mode at low and medium angles, while revealing that out-of-plane buckling was responsible for failure at high angles. Furthermore, the theory correctly predicted the sequence of various fiber and matrix failure modes. / Graduation date: 1997

Graduation date: 1994

The feasibility of developing test circuits to perform in-circuit testing of analog circuits is investigated in this thesis. A modular approach to analog testing has been adopted. Accordingly, the testing of an operational amplifier, which is a basic building block in analog circuits, is addressed. One convenient technique for measuring the frequency response of an op-amp requires a unity gain buffer to be inserted into its feedback loop. This buffer has to be simple in construction, small and accurate. Two buffer circuits that satisfy these requirements are described in this thesis. Enhanced slewing techniques are devised to achieve increased levels of performance. The buffers were integrated with an op-amp into a test chip. Digital logic is used to provide controllability and accessibility to each of the buffers and the op-amp so that they can characterized separately. The performance of the enhanced slewing buffers was verified with measurements performed on the test chip. The performance of the buffers conformed well with the simulated values. The buffers exhibited excellent settling times even while driving large capacitive loads. Their output swing and distortion performance were good for inputs as large as 2 V peak-to-peak values. / Graduation date: 1994