Reducing the amount of required propane refrigerant in the condenser of a commercial air-conditioner by increasing the inlet temperature

The use of synthetic refrigerants in the refrigeration and air conditioning sector is now obsolete due to the fact that they are not environmental friendly. They damage ozone layer and cause global warming which have both direct and indirect adverse effects on humans and environment. Today, the use of alternative refrigerants is well accepted. Hydrocarbon refrigerants are natural compounds, which do not damage the ozone layer, and have very little impact on global warming. The use of a simple hydrocarbon, propane, as a refrigerant is becoming increasingly popular these days due to its high heat capacity and its short lifetime in the atmosphere. However, since propane is extremely flammable, it is prudent to minimize the amount of propane in the system in order to reduce the risks associated with leakage of the explosive gas. In this research, the possibility of reducing the mass of propane in the condenser without sacrificing the heat transfer capacity of the system has been investigated. In an air-conditioner or refrigeration system, condenser accommodates the most mass of the refrigerant compared with those in the other parts of the system. A MATLAB script has been developed which model the performance of a commercial portable air-conditioner. The results show that by increasing the working temperature of condenser from 30oC to 46oC at the ambient temperature of 27oC, about forty percent propane mass saving is achievable. These temperatures are still far below the critical (370oC) and auto-ignition (540oC) temperatures of propane

Cost and Benefit Analysis of a Preconditioning Feeder Calf Program

Objectives were twofold: Determine key factors influencing preconditioning cost and returns; and determine the premium for age and source verified, preconditioned calves sold at a public livestock market. Data provided by the Samuel Roberts Noble Foundation show preconditioning returns depend significantly on number of days preconditioned, average daily gain, and cost of vaccinations, hay, feed, and mineral. Noble Foundation cooperators received a premium for age and source verified, preconditioned feeder cattle when sold at market. Significant coefficients averaged across five sales conclude that Noble Foundation management practices receive a $2.49/cwt premium when compared to all other cattle sold at market.Cattle, calves, preconditioning, prices, costs, age and source verification, Marketing,

Deferred Tax Positions and Incentives for Corporate Behavior Around Corporate Tax Changes

A firm's deferred tax position can influence how it is affected by a transition from one tax regime to another. We compile disaggregated deferred tax position data for a sample of large U.S. firms between 1993 and 2004 to explore how these positions might affect firm behavior before and after a pre-announced change in the statutory corporate tax rate. Our results suggest that the heterogeneous deferred tax positions of large U.S. corporations create substantial variation in the short-run effect of tax rate changes on reported earnings. Recognizing these divergent incentives is important for understanding the political economy of corporate tax reform.

A "Module" Approach to the Integration of Computer Applications Throughout the Agribusiness Curriculum

Agribusiness, Teaching/Communication/Extension/Profession,

The efficacy of after-school reading programs : a case study of a midwestern elementary school

Includes bibliographical references.The development of phonological awareness and reading comprehension skills is an important progression in reading acquisition. In this study, an analysis was used to examine the efficacy of an after-school reading program for 29 children who participated in the program. There were 14 first graders who received between 0 and .98 hours of intervention while another group of 15 first graders received between 1.17 and 2.30 hours of additional support. After an Analysis of Variance test, first group of students who received minimal intervention scored better than the students who received the most support. Despite the amount of services provided, the student who received more intervention performed more poorly on the tests than the other students who did not receive as much intervention. Factors contributing to these results include genetics and the choice of the teacher to withhold the child from services because they are believed to catch up on their own.B.S. (Bachelor of Science

The Role of the Examiner: Scholar, Reviewer, Critic, Judge, Mentor

ONLIN

School Design to Promote Physical Activity

Increasing children’s physical activity (PA) at school is a national focus to address childhood obesity. Research has demonstrated associations between school built environments and students’ PA, but has lacked a comprehensive synthesis of evidence. Chapter 1 presents new evidence-, theory-, and practice-informed school design guidelines, including evidence substantiality ratings, to promote PA in school communities. These guidelines delineate strategies for school designers, planners, and educators to create K-12 school environments conducive to PA. They also engage public health scientists in needed transdisciplinary perspectives. There have been few longitudinal studies to verify causal relationships between the school built environment and PA. Chapter 2 presents results from a natural experiment with objective PA-related measures before and after a move to a new K-5 school designed based on the Chapter 1 guidelines. The study hypothesized that the school would have desirable impacts on students’ sedentary behaviors and PA. The intervention school group was compared longitudinally with a demographically-similar group at 2 control schools. School-time analyses showed that the intervention school design had positive impact on accumulation of sedentary time, and time in light PA, likely due to movement-promoting classroom design. Studies of built environment impacts on human behaviors and health have presented challenges in control of confounding effects. Chapter 3 presents results from experiments using an agent based model (ABM) to simulate population samples of children and to quantify the impact of a single design intervention, dynamic furniture in school, on obesity and overweight prevalence over time. Results of computational experiments showed that there could be some desirable population impact among girls with low PA profiles. Chapter 4 places the work presented in Chapters 1-3 in a larger context. Via exploration of theories of space as a social phenomenon, of design as a discipline with human purpose, and of limitations of current public health built environment studies, the investigator proposes key strategies toward achieving substantial unrealized potential to design our built environments to achieve health