Large liquid rocket engine transient performance simulation system

A simulation system, ROCETS, was designed and developed to allow cost-effective computer predictions of liquid rocket engine transient performance. The system allows a user to generate a simulation of any rocket engine configuration using component modules stored in a library through high-level input commands. The system library currently contains 24 component modules, 57 sub-modules and maps, and 33 system routines and utilities. FORTRAN models from other sources can be operated in the system upon inclusion of interface information on comment cards. Operation of the simulation is simplified for the user by run, execution, and output processors. The simulation system makes available steady-state trim balance, transient operation, and linear partial generation. The system utilizes a modern equation solver for efficient operation of the simulations. Transient integration methods include integral and differential forms for the trapezoidal, first order Gear, and second order Gear corrector equations. A detailed technology test bed engine (TTBE) model was generated to be used as the acceptance test of the simulation system. The general level of model detail was that reflected in the Space Shuttle Main Engine DTM. The model successfully obtained steady-state balance in main stage operation and simulated throttle transients, including engine starts and shutdown. A NASA FORTRAN control model was obtained, ROCETS interface installed in comment cards, and operated with the TTBE model in closed-loop transient mode

Large liquid rocket engine transient performance simulation system

Phase 1 of the Rocket Engine Transient Simulation (ROCETS) program consists of seven technical tasks: architecture; system requirements; component and submodel requirements; submodel implementation; component implementation; submodel testing and verification; and subsystem testing and verification. These tasks were completed. Phase 2 of ROCETS consists of two technical tasks: Technology Test Bed Engine (TTBE) model data generation; and system testing verification. During this period specific coding of the system processors was begun and the engineering representations of Phase 1 were expanded to produce a simple model of the TTBE. As the code was completed, some minor modifications to the system architecture centering on the global variable common, GLOBVAR, were necessary to increase processor efficiency. The engineering modules completed during Phase 2 are listed: INJTOO - main injector; MCHBOO - main chamber; NOZLOO - nozzle thrust calculations; PBRNOO - preburner; PIPE02 - compressible flow without inertia; PUMPOO - polytropic pump; ROTROO - rotor torque balance/speed derivative; and TURBOO - turbine. Detailed documentation of these modules is in the Appendix. In addition to the engineering modules, several submodules were also completed. These submodules include combustion properties, component performance characteristics (maps), and specific utilities. Specific coding was begun on the system configuration processor. All functions necessary for multiple module operation were completed but the SOLVER implementation is still under development. This system, the Verification Checkout Facility (VCF) allows interactive comparison of module results to store data as well as provides an intermediate checkout of the processor code. After validation using the VCF, the engineering modules and submodules were used to build a simple TTBE

Development and Validation of an Instrument to Measure Participant Engagement in State-Federal Vocational Rehabilitation Programs

The Rehabilitation Act of 1973, as amended, calls for participants to become “active and full partners in the vocational rehabilitation process.” Although it is probable that the participant’s active engagement is a major factor in a successful vocational rehabilitation outcome, little is known about the actual meaning of engagement in the vocational rehabilitation process. This construct is often entangled with other concepts such as motivation and readiness. A clear operational definition of engagement in the vocational rehabilitation process would allow professionals to better support participants in their role. The purpose of this research was to (a) operationally define the construct of participant engagement in the vocational rehabilitation process, and (b) develop and validate an instrument to measure engagement based on this definition. After creating measurement items to reflect three proposed subdimensions of engagement (Attendance, Expected Contribution, and Homework), the items were evaluated for content validity and clarity by an expert panel and then piloted with a small group of vocational rehabilitation counselors. The refined items were then administered to a sample of public vocational rehabilitation counselors through an online survey platform. The data from the usable responses (n = 88) were summarized and then tested for an optimal factor solution using exploratory factor analysis. Next, a confirmatory factor analysis was used to confirm the adequacy of the measurement model. Finally, structural equation modeling analyses were used to identify a structural model that explained the relationships among the subdimensions and overall engagement. The results of the analyses suggest that engagement is a multidimensional construct consisting of three factors: (a) Attendance; (b) Expected Contribution; and (c) Homework. The Expected Contribution factor acts as the strongest predictor of overall engagement and also mediates the effects of Attendance and Homework on engagement. Implications of the study are provided, focusing on the need to teach participants their expected role as full partners in vocational rehabilitation. Counselors should be encouraged to facilitate high levels of engagement through competent counseling skills and appropriate counseling approaches. Finally, limitations of the research are addressed and suggestions for future research are provided

Geological evaluation of radar imagery, Appalachian Piedmont, Harford and York counties, Maryland and Pennsylvania

Geological evaluation of radar imagery of sections of Maryland and Pennsylvani

Correlations and contrasts in structural history and style between an Archaean greenstone belt and adjacent gneiss belt, NE Minnesota

An analysis of the deformation along the boundary between the Vermilion Granitic Complex (VGC) and the Vermilion district indicates that the two terranes have seen a similar deformation history since the earliest stages of folding in the area. Despite this common history, variations in structural style occur between the two terranes, such as the relative development of D sub 1 fabrics and D sub 2 shear zones, and these can be attributed to differences in the crustal levels of the two terranes during the deformation. Similarly, the local development of F sub 3 folds in the VGC, but not in the Vermilion district, is interpreted to be a result of later-D sub 2 pluton emplacement which was not significant at the level of exposure of ther Vermilion district

Salinity and Secchi Disc Records for Back Bay, Virginia (1925-1989)

All available salinity and water clarity data for Back Bay, Virginia were edited for this manuscript. Quantitative salinity records commence in 1925. These are comprehensive and extend to 1989 except for a major interruption in the 1940\u27s and 1950\u27s. Quantitative water clarity records (Secchi disc visibility) commence in 1959 and are continuous to 1989 with only a few years missing. Since 1925 the water in Back Bay has fluctuated from fresh (less than 0.5 ppt) to brackish (generally oligohaline, 0.5-3.0 ppt). Fresh to slightly brackish (less than 1.0 ppt) conditions existed from the late 1930\u27s to early 1962, from 1975 to late 1978, and in 1989. For the remainder of this 65-year period, the salinity generally ranged from 2.0 to 4.0 ppt. The higher salinity periods were 1933-34, 1936 and 1962. These were caused by voluminous intrusions of ocean water induced by hurricanes or northeastern storms. Secchi disc visibility was generally 20 to 30 inches from 1959-60 and 1965-80. During most of this period, the frequency of occurrence of submerged aquatic vegetation (SAV) in transect samples was more than 50%. From 1981 to 1989, water clarity greatly deteriorated with Secchi disc readings of only 6 to 12 inches. This increase in turbidity is attributed to the suspension of soil particles by increased wave action following a decline in SAV. Since 1980 the frequency of occurrence of SAV has been less than 5%. Without rooted, aquatic plants to stabilize the substrate, the sediment is kept in suspension by wave action

Nutrient and Total Suspended Solids Data for Back Bay (1986-1989)

Surface water samples from Back Bay, Virginia were analyzed for nutrient and total suspended solids on a monthly basis from April, 1986 through December, 1989. The concentrations of total phosphorus, erthophosphate, nitrite and nitrate nitrogen, and total ammonia generally fell within the normal range and did not indicate high nutrient loading. However, the concentrations of total suspended solids and total Kjeldahl nitrogen were high, exceeding EPA reference levels. Soil particles kept in suspension by wind driven wave action was the primary factor for the high concentration of total suspended solids. The high concentration of total Kjeldahl nitrogen was due to an abundance of organic matter, primarily plant detritus and plankton. Seasonal patterns were noted for nitrite and nitrate nitrogen, total ammonia, total suspended solids and total Kjeldahl nitrogen

Impact of Salinity Changes on Fish Populations in Back Bay, Virginia, 1950-1989

Studies conducted of Back Bay during 1950-51 and 1959-62 showed the fish populations were dominated by freshwater species. Major species included largemouth bass, channel catfish, yellow perch and carp. The average salinities during the study periods were below 0. 7 ppt. Salt water was pumped into the Bay by the City of Virginia Beach from 1965-1973 increasing the average salinity to 2.8 ppt. When pumping was discontinued in 1973, salinity decreased to pre-pumping levels until August, 1978. The fish population was surveyed in 1978, 1979 and 1980 when it was again found to be dominated by freshwater species, providing an outstanding sport fishery for largemouth bass, black crappie and bluegill. The City resumed saltwater pumping in August, 1978 and continued to August, 1987 maintaining salinities from 1.7 to 5.3 ppt. Surveys conducted during 1985 and 1986 showed the (freshwater) fishery had shifted to predominantly brackish/marine species, which included bay anchovy, white perch, spot and Atlantic menhaden. The results from rotenone and trawl/seine samples showed the fish population comprised of 74 to 97 percent brackish/marine species. After pumping was discontinued the salinity gradually declined to less than 1.0 ppt by 1989. Fish population surveys during 1989 showed an increase in freshwater fishes, mainly in the tributary creeks and canals, where over 60 percent of the fishes were freshwater