Dual-executive organizational structures are a little noted phenomenon in the religious sub-sector of the non-profit sector. These structures are ones with an administrative and religious executive both of whom answer directly to the organization’s governing board. Although dual-executive structures are known to exist, no one has so far attempted to determine the extent of their existence or the implications of their use for organization life and dynamics in the religious sub-sector. This study used a survey, sent to 150 Evangelical Lutheran and Episcopal Church congregations, to increase our knowledge of the extent of use and certain organizational implications of dual-executive structures among a sample of churches. The study had three key findings. First, it found two examples of dual executive structures. Secondly, the results suggested that national church structure may not correlate with dual executive structure use. Third, the research suggested that dual-executive structures may evidence clear division of responsibilities. Due to the study’s small sample size and is examination of evidence of the existence of dual executive structures in only two churches, these results must considered tentative and limited. / Master of Urban Affairs

Intervention programs have been developed to reduce the occurrence and recurrence of back pain and to prevent low-back injury. One program involves the wearing of abdominal support belts when manual materials handling activities are performed. However, poor postures and restricted ranges-of-motion may result due to belt usage. Unfortunately to date, the majority of research available regarding support belt effects only address those supports designed for therapeutic reasons. The primary purpose of this research was to measure changes in posture when a commercially available support belt was worn. The support belt used in this investigated was the Decade Back Support manufactured by Chase Ergonomics, Incorporated. In addition, this study investigated whether the Decade belt affected static lift strength and predicted spinal compression of the L3/L4 intervertebral disc. Eight males and eight females, aged 23.6 ± 2.6 and 22.4 ± 4.3 years respectively, were asked to perform maximal static exertions on handles attached to a steel rig. The exertions differed in symmetry and handle height while the support belt was worn and not worn. Posture data was collected through a WATSMART 3-D motion analysis system. The vertebra prominens body landmark was examined to determine if there was a change in flexion and lateral bending angle of the torso across Belt conditions. Axial twist angle between the shoulders and the hips was also investigated. Strength data was collected through a force platform across three orthogonal axes. Spinal compression was predicted through the use of the Minimum Intensity Compression (MIC) biomechanical model proposed by Bean, Chaffin, and Schultz (1988). It was found that torso posture, with the exception of axial twist, and static strength were not significantly affected by belt use. Axial twist for low asymmetric exertions was significantly larger when the belt was worn as compared to when the belt was not worn. This result may have been caused by the belt not allowing the hips to turn with the upper torso when the low exertions were performed. Maximal strength exertion was not affected by belt use. Predicted spinal compression was significantly lower when the belt was worn (2737.87 N) as compared to the nonbelt conditions (3087.47 N). / Master of Science

Solid waste management has become an increasingly costly issue for localities throughout Virginia. The Commonwealth has established a state-mandated recycling rate of 25 percent to be achieved by July 31, 1995. The mandate, however, may not adequately consider the diversity of individual localities throughout the state. Some localities may have financial, technical, or physical difficulty in complying with the mandate. Rural localities in particular may have trouble complying with mandated rates of recycling, due to the high costs and physical difficulty of collecting, separating, transporting, and marketing recyclable waste products. The focus of local recycling efforts has typically been on minimizing recycling program costs. Little attention has been given to the household costs associated with various recycling tasks or programs, and how implicit household costs associated with recycling might affect residential participation levels. Local governments often set recycling goals or implement programs with little insight into the household costs of recycling. The household’s perception of the time, effort, inconvenience, and mess involved with recycling may influence participation levels, recovery rates, and the overall effectiveness of a program. This study examines and discusses the factors that influence the recycling behavior of rural residents. It also provides an indication as to the household perception of the implicit costs associated with various recycling tasks. Three separate recycling programs are examined to determine if household recycling behavior differs between counties, depending on the type of waste disposal and recycling system used in the county. / Master of Science

An important aspect of all spread spectrum receivers is synchronization. The harsh radio environment has necessitated the development of fast and robust techniques. Current techniques for direct sequence spread spectrum (DSSS) synchronization, although rapid, are not robust to multiple access interference. This is because they require the spreading codes of the multiple access network to have very good cross correlation properties. In this thesis, a novel technique for DSSS synchronization is investigated. This technique, termed as the eigenstructure technique, introduces a new approach to synchronization, called soft synchronization, by which spread spectrum despreading is performed with estimates of the spreading code obtained from the received signal, starting at an early stage. As more data is collected, the code estimate improves and so does the quality of the despread data. The key advantage of the soft synchronization technique is that excellent despread data can be obtained using imperfect, but early, code estimates. The eigenstructure technique exploits the cyclostationarity property of the DSSS signal. It can theoretically provide perfect code estimates for signals received in arbitrary levels of white background noise and with arbitrary timing offsets and is insensitive to frequency offsets on the received signal. It is applicable to DSSS signals with a constant modulus code and requires the knowledge of only the code repetition rate. The technique is robust to multiple access interference provided the users have different code repetition rates. / Master of Science

Several aspects of wildflower meadow establishment using native Virginia herbaceous perennial species were investigated. The initial task lay in identifying the truly native species from those European introductions which have successfully naturalized in the state. Germination testing was conducted in accordance with procedures deemed feasible for use by the Virginia Department of Transportation. Direct seeding in the field, either in spring or fall, failed to produce acceptable levels of emergent plants. Under two treatments conducted in the greenhouse many species germinated well. Weed control is the most critical factor in successful wildflower meadow establishment. Dacthal®, Pennant®, and Treflan® all suppressed germination and/or retarded development of at least some of the five species tested. Use of these three herbicides is not recommended in conjunction with seeding of Virginia wildflowers. Direct seeding a nurse crop of non-persistent species in the spring which would be followed by installation of the native mix in the fall was investigated. Soil analysis and subsequent development of the Virginia wildflower mix failed to differentiate any soil quality influence of the nurse crop as compared to the other two treatments. Direct seeding was compared to the use of the Virginia Tech Transplanted Meadow (VTTM) technique developed by Lyons for fall establishment. High levels of winter survival, strong competitive ability against weeds, and good spring growth by the wildflower species indicate that the VTTM technique is a promising method for establishing wildflower meadows. Further research is needed to determine the long term performance of a native Virginia wildflower meadow. / Master of Science

This study is part of a project aimed at investigating the reasons for the noise generation and sound propagation in the hermetically sealed H25A air conditioner compressor manufactured by Bristol Compressor Co. This study aims to investigate the pressure fluctuations inside the compressor cavity and their effect on the forces generated by the impact of valves on valve seats and valve stops. In order to achieve this objective a computer program, which mathematically simulates the operation of the compressor, was written. The simulation program is capable of predicting the pressure fluctuations inside the cylinders as well as the various Cavities inside the compressor. The pressure driven forces on the suction and discharge valves can then be computed and their effect on the forces transmitted to the compressor shell be studied. The results from an earlier experimental study were used in order to verify the results generated by the simulation program. The results from the simulation program were comparable to the experimental values. / Master of Science

Vibration testing and analysis is becoming increasingly important in the electronics industry. It is used as a workmanship screen, as well as a way to duplicate the deployed environment in both the military and commercial avionics worlds. To minimize the effects of the vibration from testing and what will be encountered in service, the mechanical analyst must be able to accurately predict mode shapes and frequencies of in-situ PC board. This thesis will investigate modeling the wedge locks as non-uniform translational and rotational springs. The first eight natural frequencies of a rectangular circuit board (with no components soldered to it, and with wedge locks along two edges) will be empirically determined. Eight frequencies will be used to solve for four unknowns: continuously distributed translational and rotational spring stiffnesses along the segments of board that are in contact (two unknowns) with the wedge lock, and those that are not in contact (two unknowns). A finite element model will be developed of the physical system. The translational and rotational spring stiffnesses will be optimized to minimize an error function involving the difference between the empirical and analytically predicted natural frequencies. / Master of Science

A literature review was performed to investigate the current status of two-cycle gasoline engines from the standpoint of design, performance, benefits, lubrication and emissions. The two-stroke engine offers several significant advantages over its four-stroke counterpart, which include: simple design, low production cost, higher power to weight ratio, smaller size, lower peak operating temperatures, and lower NO𝗑 emissions. The main drawbacks of two-stroke engines are the high unburned hydrocarbon and particulate exhaust emissions which are attributed to the lubricating oil and the scavenge process. Technologies to reduce exhaust emissions from two-stroke engines are strongly contingent on the ability to develop improved, environmentally friendly, lubricants which can be used at high fuel:oil ratios. An experimental study of lubrication of an air-cooled, two-stroke, gasoline engine by tribopolymerization is presented. Tribopolymerization is defined as the planned or intentional formation of protective polymeric films directly and continuously on rubbing surfaces to reduce damage and wear by the use of minor concentrations of selected compounds capable of forming polymeric films in situ[12]. Two monomers were investigated as potential anti-wear compounds, namely (a) Cas dimer acid/ethylene glycol monoester, a condensation monomer, and (b) diallyl phthalate, an addition monomer. The condensation monomer was found to provide sufficient wear protection under a range of unloaded test conditions. Under loaded test conditions, however, piston scuffing occurred well before the planned test period of 20 hours had expired with all of the lubricants tested. Photomacrograph and SEM photographs reveal rather thick deposits on the monoester lubricated piston using a mass concentration of 0.5% monoester in gasoline. The heavy deposits were not noted using a mass concentration of 0.5% diallyl phthalate or with a 0.1% mass concentration of the monoester in bis (2-ethylhexyl) sebacate, a synthetic base oil. As a secondary topic which parallels this study, other existing and rising fuel lubricity problems have been investigated. The poor friction and wear characteristics of diesel, jet, and alcohol fuels have led to tribological problems in various engine fuel system components. The outstanding anti-wear performance of monomer additives in several similar tribological systems in the past shows good potential for the solution to a variety of current fuel lubricity problems. / Master of Science

The purpose of this study was to investigate the effects of keyboard height, the presence or absence of a wrist support, and keying time on different risk factors associated with musculoskeletal disorders experienced by VDT operators. Measurements of wrist posture, activity of the trapezius muscles, shoulder abduction and typing performance were recorded at fixed intervals during a controlled 40 minute keying task. Ratings of musculoskeletal comfort were recorded before and after each keying task. Six subjects performed the keying tasks on six different days. A different keyboard height and wrist support condition was tested on each day. For wrist extension, ANOVA showed that the effects of Keyboard Height, Wrist Support, and Height x Keying Time were significant. For ulnar deviation, the main effects of Keyboard Height and Keying Time were significant. For forearm pronation, only the effect of Wrist Support was significant. Mean shoulder abduction ranged between 0 and 2 degrees. Mean EMG activity for all keying tasks was 5.3 %MVC. Subjects made an average of 26.5 errors during each keying task (.6 errors/min.), and an average of 1.64 errors for each time interval (.8 errors/min.). For the reported change in musculoskeletal comfort of the back, neck, left and right shoulders, left and right upper arms, left and right forearms, left wrist, and left hand, the main effect of Wrist Support was significant. In all cases the decrease in musculoskeletal comfort was greater when the wrist support was absent. Subjects preferred wrist supports, and heights at or greater than seated elbow height. The keying condition that was preferred most by subjects was when the keyboard was positioned at elbow height and when the wrist support present. The condition preferred least was when the keyboard was positioned 5 cm below elbow height and when the wrist support was absent. These results indicate that the use of wrist supports can decrease wrist extension and musculoskeletal discomfort during keying tasks. Keyboard heights at or above seated elbow height may help decrease wrist extension but keyboard heights above elbow height may increase ulnar deviation. / Master of Science

The objective of this study is to design a composite that mimics the mechanical performance of a tendon. The biomimetic composite structure was composed of an elastomeric matrix reinforced with continuous polymer fibers. The matrix material was a thermoplastic polyurethane, Estane 5714 F5P. A polyamide (Nylon 6-6), a polyethylene terephthalate (Dacron) and a block copolymer of polyethylene oxide and aromatic polyurethane (Lycra) were used as the straight fiber reinforcement A crimped Nylon 6 fiber was obtained in order to simulate the crimp in natural tendon. The composites were manufactured with the polymer matrix in solution form. A solution of the polyurethane and tetrahydrofuran was used to coat the fibers using a single-tow coating device. The effect of structure of the composite on the mechanical properties was examined by manufacturing composites with three different structures: straight fiber reinforced, crimped fiber reinforced and braided composites. The composites were then examined for physical and mechanical properties. All of the composites exceeded the natural tendon's breaking strength and elongation to failure. Through biomimicking, a composite was manufactured with a higher initial stiffness and strength than the crimped nylon fiber. The shape of the stress-strain curves of tendon and the synthetic composites were also compared. The scale of the structure of the composites was compared to that of tendon. A non-dimensional ratio of the periodicity of the crimp to filament size (R) revealed a much larger level of structure in the synthetic composites than in the tendon. This ratio was found to have a correlation to the mechanical properties of the composites. / Master of Science