A laboratory model of an instrument concept to measure the absorption of solar radiation by atmospheric aerosols was designed, built and tested. The concept was based on the photophonic phenomenon discovered by Bell and an acoustic resonator developed by Helmholtz. The design consisted of two chambers: an aerosol chamber and a reference chamber combined into a double Helmholtz resonator configuration. The radiation from the visible light source was amplitude modulated by a mechanical chopper. The modulated light beam was passed through the chambers and pressure variations resulted from energy absorbed by the aerosol in the chamber. The pressure signal was sensed by microphones, then the electrical signal amplified and processed by a differential amplifier. The testing showed the instrument had sufficient sensitivity and low enough system noise to measure an absorption coefficient of about 10⁻⁶/meter. Methods of signal improvement and noise reduction were discussed and tested. The results showed the instrument could measure absorption coefficients within the range expected by the earth's atmospheric aerosols. The instrument design was not optimized for maximum signal or minimum noise, but the justifiable conclusion was reached that the concept showed the promise of leading to a useful instrument in the measurement of atmospheric aerosol absorption and an improvement over the present instruments. / Master of Science

Late instar larval Alphitobius diaperinus initiated tunneling damage to polystyrene insulation in search of protected pupation sites. Adult females oviposited upon the surface of the styrofoam but early instar larvae left the styrofoam soon after hatching. Within twenty days, large numbers of adults moved into the styrofoam, expanding the tunnels and depreciating the panels' suitability as pupation sites for the late instar larvae. No oviposition occurred within the tunnels. All lifestages of Alphitobius diaperinus were found to be cannibalistic. Although preliminary tests show that adult mealworms will consume house fly late instar larvae and prepupae, no significant predation of the house fly by A. diaperinus could be detected under simulated natural conditions at the population density tested. Wettable powder formulations of permethrin and carbaryl when sprayed upon styrofoam were comparable in residual activity. Residual activity of both compounds was less when applied to unpainted plywood. The emulsifiable concentrate formulation of permethrin proved to be ineffective. Regression slopes from topical application studies reveal that tetrachlorvinphos may be the material of choice against A. diaperinus because there is less chance of the lesser mealworm developing resistance to tetrachlorvinphos than with either permethrin or carbaryl. Tetrachlorvinphos also showed longer residual effectiveness against A. diaperinus as a surface spray on styrofoam and plywood than did permethrin or carbaryl. / Master of Science

Strains evaluated were Ennis (EN, domestic), Fish Lake (FL, wild), Mcconaughy (MC, wild), FGL Standard Winter (SW, domestic), and Sand Creek (SC, semiwild). In 1981, four Virginia put-and-take streams were stocked with 150 and 50 of each strain in March and May, respectively. Creel and electrofishing surveys were conducted to determine harvest, movement and survival after fishing. A reference (unfished) stream was also selected and stocked with 50 of each strain, and electrofishing surveys were conducted to determine survival, growth and movement. SW and EN strains were caught by anglers primarily during opening weekend (April 4-5, 1981), while the FL and SC strains were caught throughout the creel survey period. The MC strain was consistently lowest for total estimated harvest, while the SC and SW strains were equally high in total estimated harvest. Significant differences occurred in the proportional relationships of strain harvests among streams. May harvest results generally corroborated April results, except that significant differences among streams were not found. Greater survival for strains with low harvests during April was not evident in fished streams. Natural mortality rates in the reference stream did not differ significantly among strains between May 20 and October 22, 1981. Change in average length of the strains over four months in Spring Branch ranged from -4.3 mm for EN to +18.9 mm for SW. Percentage of stocked biomass of the SW strain remaining after five months (20.8%) in the reference stream was more than twice that remaining for the EN (9.6%) and SC (9.4%) strains. No significant differences in downstream movement, and no significant upstream movements, were observed for strains in the fished and reference streams. / Master of Science

In order to increase the usefulness of the nuclear research reactor, it is necessary to enhance the neutron fluxes available in the experimental facilities. One method of attaining this objective is to increase the power level of the reactor. The VPI&SU 100 KW research reactor has been studied to investigate the feasibility of operation of 500 KW. From a thermal-hydraulic point of view, the following limiting conditions should not be exceeded for a 500 KW operation: 1) bulk boiling of the coolant should not occur, 2) surface boiling should not occur on any fuel plate, 3) fuel meltdown must not occur after a loss-of-flow or loss-of-coolant accident, 4) fuel plate vibration problems should not be significant. The results of the investigation indicate that the above limiting conditions will not be exceeded provided that certain system modifications are made. Thus the operation of the VPI&SU reactor at 500 KW is feasible as far as thermal-hydraulics is concerned. / Master of Science

The rate of the aqueous transformation of aragonite to calcite was measured at 50°, 77°, and 101°C. The observed mole fraction calcite versus time relationship can be fit by the integrated rate model: t = [(3/C₂)(1-X)2/3 + (3/C₁)(X2/3)/[K₂-K₁] The constants C₁ and C₂ combine geometric factors, especially relative surface areas of the solids, K₁ and K₂ are the thermodynamic equilibrium constants for aragonite and calcite respectively. Apparent activation energies (E_A’) and absolute rates were calculated from Arrhenius plots of data from this study and others: E_A’ Conditions Material Time-50% CAL, 25°C Metzger and Barnard, 1968 58 kJ mol⁻¹ wet cm cubes 2.25X10² yr Taft, 1967 67 wet syn. powder 2.0X10⁻¹ This study 55 wet syn. powder 5.7X10⁻² Brown et al.,1962 373 dry 4.7X10³³ The E_A’ for this study is comparable with that of Metzger and Barnard indicating a similar mechanism, but absolute rates differ dramatically because of the different geometries of the run material. The dry transformation rates are so slow at diagenetic temperatures that this mechanism is of no importance geologically. Because the rate of the transformation is dependent on the geometry of the reacting system it is not surprising that most studies of neomorphic calcites find that the calcite textures are related to the original aragonite textures. Three transformation regimes, macroscale (passive dissolution), mesoscale (chalk zone), and microscale (thin film) dissolution-precipitation, are proposed to explain the variability in observed diagenetic calcite textures. These are differentiated by the surface area/solution ratio in the reaction zone. In general the smaller the geometric factor in the rate equation. i.e. the smaller the surface area/solution ratio, the slower the transformation rate and the higher the degree of precursor fabric retention in the neomorphic calcite. / Master of Science

Twenty-four male university students were fed vegetarian diets containing 100 grams of protein. Seventy-five grams of protein came either from soy, non-fat dairy products or egg white. Diets were adjusted so that differences in total caloric intake, protein, carbohydrate, fat and fatty acid composition were minimal between the dietary treatments. Plasma total triglyceride and very low density lipoprotein-triglycerides were measured at the beginning, weekly throughout the experimental period, and two weeks after completion of the study. No significant differences existed in serum lipid values between treatment diets nor was any interaction between diet and week observed. A significant week effect was observed indicating that subjects fed soy, non-fat dairy products or egg whites responded in the same fashion to the diet from week to week. This relationship was true for both variables: serum triglycerides and VLDL-triglycerides. Serum triglyceride concentrations for all treatment groups combined at baseline were 79 mg/ 100 ml, increasing to 82 mg/100 ml at week 1 and decreasing to 64 mg/100 ml at week two. An increase of 84 mg/100 ml was noted at week three. Decreases were observed at week four, with serum concentrations of 65 mg/100 ml. From week four to follow-up serum triglyceride concentration rose to 83 mg/100 ml. Similar trends were noted in serum VLDL-triglyceride levels when mean concentration were combined for all treatment groups. Serum VLDL-triglyceride concentrations at baseline were 48 mg/100 ml. At week one serum VLDL-triglyceride concentrations remained unchanged with values of 40 mg/100 ml in both instances. Decreases were observed at week 4 with serum VLDL-triglyceride concentrations increased to 38 mg/100 ml. The results indicate that plasma triglycerides and VLDL-triglycerides are influenced by other dietary factors rather than by the protein source. / Master of Science

Planktonic Foraminifera were examined from the Aquia Formation (Late Paleocene) from 2 localities in the Aquia type area along the Potomac River 7 miles southeast of Stafford, Virginia to: identify taxa present, and to effect biostratigraphic correlation with other Paleocene studies on the Virginia Coastal Plain. Two genera and twenty-two species were recovered, allowing recognition of the Globorotalia pseudomenardii and Globorotalia velascoensis zones, and correlation with The Oak Grove Core, 23 miles to the southeast (Gibson, et al. 1980), and a Pamunkey River locality 50 miles to the south (Seaton, 1982). This correlation shows equal thicknesses of the Aquia within zonal boundaries over the Potomac River - Oak Grove - Pamunkey River area, suggesting uniform rates of Aquia sedimentation in this portion of the Salisbury Embayment. Correlation of the Oak Grove Core, which was zoned via the Tertiary NP zonation indicates the presence of NP zones 5,6-?7,8,9 in the Aquia type area. / Master of Science

The S-D-R (Saw-Dry-Rip) process is a proven method of reducing warp in manufacturing hardwood studs. It has been assumed that its success is partially due to the stress relaxation caused by high-temperature drying. Implementation of this S-D-R process in the Appalachian region has been limited as few mills in this area have this drying capability. The purpose of this study was to investigate the effectiveness of high-temperature and steaming treatments before solar and air drying S-D-R flitches on reducing warp and to determine the cost of application of successful methods. An initial study was conducted to establish the duration of treatment required to relieve growth stresses in short S-D-R flitches. Steaming for 15 hours resulted in a substantial decrease of average stress. Steaming times of 15 and 20 hours and high-temperature durations of 7 and 15 hours were chosen for treating green S-D-R flitches. S-D-R flitches were divided among the four treatments and a control group. One third of the flitches from each group were subsequently dried in a solar kiln; the rest were air dried. All flitches were then ripped into 2 x 4's and bow, crook, and twist was measured for each stud. A comparison by the percentage of studs rejected from No. 2 dimension because of warp showed no significant difference between any treatments (including the control) or between drying methods. Comparisons based on actual amount of warp found small differences between drying methods and between treatments, depending on the type of warp considered. / Master of Science

An experimental investigation of the solidification of a fully developed turbulent internal flow due to external cooling of the tube wall was conducted. A region of unstable freezing behavior was located and bounded in terms of initial Reynolds number and a nondimensional temperature parameter for the given system. This region was observed over the span of Reynolds numbers from 4500 to 10150 and was defined to exist at values of the pertinent parameters between those which cause a smooth steady-state response and those which cause a smooth response resulting in complete tube blockage. An increase in upstream flow resistance was found to make the region of instability less sensitive to a change in coolant temperature at constant initial Reynolds number. System blockage was predicted in terms of steady-state freezing data at constant nondimensional temperature and various initial Reynolds numbers. / Master of Science

In the past, passive SONAR range tracking systems have used Extended Kalman filters to process nonlinear time-delay measurements. This approach has several flaws due to the inherent divergence problems of Extended Kalman filters. This paper discusses a new approach which uses a prefilter to linearize the measurements so that they can be processed by a standard Kalman filter. The approach is subsequently expanded for use with an adaptive Kalman filter which allows source maneuvers to be tracked. A new approach to passive Doppler velocity tracking is also proposed which uses a dedicated Kalman filter to track random fluctuations in the sources center frequency. This dedicated tracker simplifies the problem so that it can be handled by a basic adaptive Kalman filter. / Master of Science