Clustering of Ionizing Sources

Using existing models for the evolution of clustering we show that the first sources are likely to be highly biased and thus strongly clustered. We compute intensity fluctuations for clustered sources in a uniform IGM. The strong fluctuations imply the universe was reheated and reionized in a highly inhomogeneous fashion.Comment: 4 pages, 3 figures, to appear in the proceedings of "After the Dark Ages: When Galaxies were Young (the Universe at 2<z<5)", 9th Annual October Astrophysics Conference in Marylan

Properties of glass fiber reinforced self compacting concrete

Self Compacting Concrete (SCC) is able to flow under its own weight and completely fill the formwork, even in the presence of congested reinforcement, without any compaction, while maintaining homogeneity of the concrete. Majority of concrete cast rely on compaction to produce good quality concrete. However, compaction is difficult to be done in conditions where there are dense reinforcement and large casting area. Usage of SCC will overcome the difficult casting conditions and reduce manpower required. Addition of fibers will enhance the tensile and ductile behaviour of concrete with brittle nature. SCC was added with relatively short, discrete, and discontinuous glass fibers to produce Glass Fiber Reinforced Self Compacting Concrete (GFRSCC). The purpose of this study is to investigate the workability and mechanical properties of plain SCC and GFRSCC. Control concrete (NC), plain SCC, and GFRSCC samples were prepared. Water-cement ratio of 0.40 was used for all concrete mixes. The fiber and brand of superplasticizer used were alkaline-resistance glass fiber and Rheobuild 1100, respectively. Three fiber contents of 0.5%, 1.0%, and 1.5% by volume of concrete were utilised in this study. The laboratory testing included slump flow test, L-Box test, sieve segregation resistance test, density test, ultrasonic pulse velocity (UPV) test, compressive strength test, splitting tensile strength test, and flexural strength test. The dosage of superplasticizer required increased as fiber content increased. Plain SCC and GFRSCC were highly workable than NC. The experimental results show that plain SCC exhibited higher compressive strength than NC and GFRSCC. The splitting tensile strength of NC was higher than plain SCC and GFRSCC due to negative effect of superplasticizer added. The flexural strength of NC was slightly higher than plain SCC. All GFRSCC exhibited higher flexural strength than plain SCC. The optimum fiber content was 1.0% by volume of concrete. GFRSCC with 1.0% fiber content developed higher load at first crack and ultimate load than NC and plain SCC slabs

Evolutionary Concept, Genetic Algorithm and Exhibition Contract in Movie Industry

The paper is about application of evolutionary concept, particularly the application of natural selection process, to the study of movie industry. The importance of the application is that it allows for the heterogeneity and interdependency of market agents in analyzing the economic choice decision. This complexity always presents an obstacle to the study of market behavior, especially when one has to take into account the constant reinforcing effects among the variables, which often renders the problem elusive. The paper intends to explain the economic process, particularly the evolution of exhibition contract, taking into account this complexity through the use of evolutionary concept.Evolutionary selection; opportunity costs; learning and sharing rule

Assurance Problem in Gift Exchange Game: An Experimental Study

The workers’ reciprocity in a simple Gift Exchange Game has been demonstrated in prior research to be enforcement problem. We showed that potential future interactions could not motivate the workers significantly because of assurance problem. Lack of information about employers’ reciprocal type made workers reluctant to cooperate. We conducted three experimental treatments to investigate the effort patterns. We found that workers’ efforts were not significantly different between with and without repetition effect. Workers did not cooperate much even when there was enforcement. The assurance problem was overcome when workers could judge the reciprocal type of the employer by comparing current wage with market wage. We found that workers responded more to market wage than current wage and were significantly more cooperative.Reciprocity; Assurance Problem;Wage Rent; Focal Point

Evolutionary Concept, Genetic Algorithm and Exhibition Contract in Movie Industry

The paper is about application of evolutionary concept, particularly the application of natural selection process, to the study of movie industry. The importance of the application is that it allows for the heterogeneity and interdependency of market agents in analyzing the economic choice decision. This complexity always presents an obstacle to the study of market behavior, especially when one has to take into account the constant reinforcing effects among the variables, which often renders the problem elusive. The paper intends to explain the economic process, taking into account this complexity through the use of evolutionary concept.Evolutionary selection; opportunity costs; learning and sharing rule

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

Individual tradable permit market and traffic congestion: An experimental study

This paper investigates the potential of an individual tradable permit system in an experimental two-sided repeated double auction market to overcome over-consumption through road demand management. The evaluation of this system shows that traders exhibit strong dependence on reservation price and there are significant transfers of permit from low value users to high value users. During peak hours, the permit price increases owing to high demand, so the cost of using the road is high during congestion. This creates incentive for low value drivers to postpone their trips and resell permits in the peak hours to gain profit. The results show the delayer pays principle, in which drivers who value highly have to pay drivers who are willing to stay off the road during peak hours.: Individual tradable permit, Congestion, High value and low value drivers, Allocative efficiency