Solar array electrical performance assessment for Space Station Freedom

Electrical power for Space Station Freedom will be generated by large Photovoltaic arrays with a beginning of life power requirement of 30.8 kW per array. The solar arrays will operate in a Low Earth Orbit (LEO) over a design life of fifteen years. This paper provides an analysis of the predicted solar array electrical performance over the design life and presents a summary of supporting analysis and test data for the assigned model parameters and performance loss factors. Each model parameter and loss factor is assessed based upon program requirements, component analysis, and test data to date. A description of the LMSC performance model, future test plans, and predicted performance ranges are also given

Acquisitions and Regulatory Arbitrage by Captive Finance Companies

Captive finance firms play an important role as financial intermediaries. Yet, they receive little attention in financial research. Recently, finance companies have grown by engaging in acquisition activities. Given their unique characteristics, finance companies may be more capable of extracting gains from acquisitions than other firms. We explain their advantages, and assess the market response and long-term valuation of finance companies that engage in acquisitions. Our results indicate that acquisitions by captive finance firms are wealth enhancing in the short term and the long term. However, the market reacts negatively when flexible captive financing firms acquire highly regulated depository institutions

Acquisitions and Regulatory Arbitrage by Captive Finance Companies

Captive finance firms play an important role as financial intermediaries. Yet, they receive little attention in financial research. Recently, finance companies have grown by engaging in acquisition activities. Given their unique characteristics, finance companies may be more capable of extracting gains from acquisitions than other firms. We explain their advantages, and assess the market response and long-term valuation of finance companies that engage in acquisitions. Our results indicate that acquisitions by captive finance firms are wealth enhancing in the short term and the long term. However, the market reacts negatively when flexible captive financing firms acquire highly regulated depository institutions

ACCURACY OF DIGITIZATION USING AUTOMATED AND MANUAL METHODS

The objective of this study was to determine the limits of accuracy of angular estimates produced by a computerized three-dimensional (3-D) motion measurement system using auto-digitization and manual digitization. We hypothesized that auto-digitization would produce more accurate and reliable estimates of angular data than manual digitization. Twelve reference angles were estimated from markers placed on a T-shaped pendulum. The pendulum’s angular velocity was systematically increased by changing the release position from four angles (0 -static, 45 , 90 , and 120 ). Angular estimates were compared over 20 frames for 10 trials at each release position using analysis of variance (ANOVA), and intra-class correlation coefficients (ICC’s) were used to estimate the variability among release positions. Two S-VHS camcorders were placed at 45 angles relative to the activity plane for filming, forming an inter-camera angle of 90 . The cameras operated at a film speed of 60 Hz, with a shutter speed of 1/500 second. A single 300-W flood light was positioned beside each camera to illuminate 1.90 cm diameter retro reflective markers. A 3-D calibration structure defined a calibration area 182.88 cm wide, 152.40 cm high, and 60.96 cm deep. Eighty independent film clips (4 angular velocities X 10 trials X 2 views) were manually digitized across 20 frames by five experienced digitizers. Data was transformed to 3-D coordinates using a DLT, and smoothed with a Butterworth second-order, low-pass recursive filter with a fc of 6 Hz. Mean errors of the angular estimates across trials and frames were within ±1.0 for each of the four release positions. ANOVA and a post-hoc Tukey test revealed the mean error of the auto-digitized trials was statistically larger (

Resistance training volume, energy balance and weight management: Rationale and design of a 9 month trial

The increased prevalence of obesity and the lack of treatment success both argue for the design and evaluation of strategies to prevent the development of overweight and obesity. To date, the role of resistance training (RT) in this regard is largely unexplored. RT may be effective for weight management as a result of increased fat-free mass (FFM), which may result in increased resting metabolic rate and increased physical activity energy expenditure. However, the literature relative to the efficacy of RT protocols recommended for healthy adults to alter the aforementioned parameters is inconsistent or inadequately evaluated. We will conduct a 9 month randomized controlled efficacy trial to compare changes in body composition (fat mass, FFM, % body fat) and energy balance in response to 2 volumes of RT (1 vs. 3 sets vs. non-exercise control) both at the completion of training (9 months) and 1 year later (body composition). This investigation will be conducted in a sample of healthy, normal and overweight, sedentary, young adult men and women; a group at high risk for development of overweight and obesity. Our results will provide information relative to the minimum volume of RT that may be associated with body weight/fat gain which may inform the development of guidelines for RT to prevent weight gain or to alter body composition

Comparison of Solar Electric and Chemical Propulsion Missions

Solar Electric Propulsion (SEP) offers fuel efficiency and mission robustness for spacecraft. The combination of solar power and electric propulsion engines is currently used for missions ranging from geostationary stationkeeping to deep space science because of these benefits. Both solar power and electric propulsion technologies have progressed to the point where higher electric power systems can be considered, making substantial cargo missions and potentially human missions viable. This paper evaluates and compares representative lunar, Mars, and Sun-Earth Langrangian point missions using SEP and chemical propulsion subsystems. The potential benefits and limitations are discussed along with technology gaps that need to be resolved for such missions to become possible. The connection to NASA's human architecture and technology development efforts will be discussed