Non-tracking solar energy collector system

A solar energy collector system characterized by an improved concentrator for directing incident rays of solar energy on parallel vacuum-jacketed receivers or absorbers is described. Numerous individually mounted reflector modules of a common asymmetrical triangular cross-sectional configuration are supported for independent reorientation. Asymmetric vee-trough concentrators are defined

Solar energy receiver for a Stirling engine

A solar energy receiver includes a separable endless wall formed of a ceramic material in which a cavity of substantially cylindrical configuration is defined for entrapping solar flux. An acceptance aperture is adapted to admit to the cavity a concentrated beam of solar energy. The wall is characterized by at least one pair of contiguously related segments separated by lines of cleavage intercepting the aperture. At least one of the segments is supported for pivotal displacement. A thermal-responsive actuator is adapted to respond to excessive temperatures within the cavity for initiating pivoted displacement of one segment, whereby thermal flux is permitted to escape from the cavity

Solar energy collection system

An improved solar energy collection system, having enhanced energy collection and conversion capabilities, is delineated. The system is characterized by a plurality of receivers suspended above a heliostat field comprising a multiplicity of reflector surfaces, each being adapted to direct a concentrated beam of solar energy to illuminate a target surface for a given receiver. A magnitude of efficiency, suitable for effectively competing with systems employed in collecting and converting energy extracted from fossil fuels, is indicated

A Nomographic Methodology for Use in Performance Trade-Off Studies of Parabolic Dish Solar Power Modules

A simple graphical method was developed to undertake technical design trade-off studies for individual parabolic dish models comprising a two-axis tracking parabolic dish with a cavity receiver and power conversion assembly at the focal point. The results of these technical studies are then used in performing the techno-economic analyses required for determining appropriate subsystem sizing. Selected graphs that characterize the performance of subsystems within the module were arranged in the form of a nomogram that would enable an investigator to carry out several design trade-off studies. Key performance parameters encompassed in the nomogram include receiver losses, intercept factor, engine rating, and engine efficiency. Design and operation parameters such as concentrator size, receiver type (open or windowed aperture), receiver aperture size, operating temperature of the receiver and engine, engine partial load characteristics, concentrator slope error, and the type of reflector surface, are also included in the graphical solution. Cost considerations are not included

Optimal subset-difference broadcast encryption with free riders

Cataloged from PDF version of article.Broadcast encryption (BE) deals with secure transmission of a message to a group of receivers such that only an authorized subset of receivers can decrypt the message. The transmission cost of a BE system can be reduced considerably if a limited number of free riders can be tolerated in the system. in this paper, we study the problem of how to optimally place a given number of free riders in a subset-difference (SD)-based BE system, which is currently the most efficient BE scheme in use and has also been incorporated in standards, and we propose a polynomial-time optimal placement algorithm and three more efficient heuristics for this problem. Simulation experiments show that SD-based BE schemes can benefit significantly from the proposed algorithms. (C) 2009 Elsevier Inc. All rights reserved

Sustainable Environment and in the Context of Environment Economy Necessary and an Analyze

In global world, the environment has become a scarce resource. Since economics is about how to deal with scarce resources, environment and economics are interrelated with each other. On the other hand it is also clear that economics which creates both positive and negative externalities, affects the environment. For this reason, it is not possible to except environmental problems from the economics. Today some socio-economic activities like increasing consumption based on shopping malls, urban regeneration, fast population growth and etc. have being created environmental cost. One way of using economics is to ensure that the costs and the benefits of environmental measures are well balanced. Although it is difficult to estimate costs and benefits, there is an increasing demand that this is should be done before the economical activity. Economic and environmental objectives are often perceived as being contradictory. It is believed that a choice must be made between one and the other and that cannot be achieved concurrently. To change this perception, some measures should be taken on both national and international level.  At this point, an efficient environmental auditing is being important day by day to ensure environmental economics. In this study we will research what was done in the world in terms of environmental economics. In this context, we will examine what will have to do in Turkey in terms of legislation

Detection of human cytomegalovirus and Epstein-Barr virus in symptomatic and asymptomatic apical periodontitis lesions by real-time PCR

Objectives: Recent studies have investigated the occurrence of human cytomegalovirus and Epstein-Barr Virus in samples from apical periodontitis lesions and a role in the pathogenesis of this disease has been suggested. Because genotype distribution and seroprevalence of EBV and HCMV differ among populations, it is important to determine the presence of these viruses in endodontic periapical lesions of different populations. The aims of this study were to determine the presence of HCMV and EBV DNAs in samples from Turkish patients with symptomatic and asymptomatic apical periodontitis lesions using real-time polymerase chain reaction method and to evaluate their presence in both symptomatic and asymptomatic apical periodontitis lesions. Study Design: Periapical samples were collected from 12 asymptomatic and 16 symptomatic periapical lesions in conjunction with apicectomy. HCMV and EBV DNAs were identified in the samples by real-time PCR. The chi- squared test with Yates's correction or the Fisher's exact test was used to analyse the significance of differences. Results: HCMV DNA was detected in 10 of the 16 (62.5%) symptomatic and in five of the 12 (41.7 %) asymptomatic periapical study lesions. The EBV DNA was identified in seven of the 16 (43.7 %) symptomatic and three of the 12 (25 %) asymptomatic periapical lesions. The difference in occurrence of HCMV and EBV DNA between symptomatic and asymptomatic periapical lesions was not statistically significant. (All comparisons have p > 0.05). Conclusions: Our findings suggest that HCMV and EBV is a frequent inhabitant of both symptomatic and asymptomatic apical periodontitis lesions of endodontic origin in Turkish population

Expansion for Who, Markets or the Poor?

Abstract: In this study we examine the impacts of monetary expansion policies executed by the Federal Reserve on poverty in the United States of America. It has been discussed in various studies that the Fed’s expansionary monetary policies create a less positive impact on economy as a whole than financial sector. In this study, the expansionary effects of policies on the poor living in America will be discussed. The main thesis of the study is that the poor living in the United States benefited less from expansionary monetary policies than either financial sector or the US economy as a whole. When discussing the thesis of the study both employed and unemployed poor will be discussed. Therefore, it will be questioned that the decrease in the unemployment rate is the indicator of the fight against poverty. Indicators such as indices and interest rates in the financial markets, and indicators such as growth rates and unemployment rates in the non-financial markets are regarded as essential indicators but as for poverty it’s hard to find such regarded indicators. Unfortunately, there are not too many statistics about the poor living in the United States in the reports of the international organizations. Thus the main trouble of the study is that international comparisons are almost impossible. Therefore, various indicators produced by the U.S. government agencies of various indicators will be used in this study

Assessment of material properties of gallium orthophosphate piezoelectric elements for development of phased array probes for continuous operation at 580 degrees C

In this paper, the thickness extension mode gallium orthophosphate single crystal elements were characterised using the impedance analyser. Impedance characteristics of piezoelectric elements were investigated at temperatures from 25°C up to 580°C at first and then at a constant temperature of 580°C for a period of 25 days. The resonant and anti-resonant frequencies extracted from the impedance characteristics, capacitance (measured at 1 kHz), density and dimensions of the gallium orthophosphate elements were used to calculate electromechanical, piezoelectric and elastic properties of these elements at high temperatures as a function of time. The tested gallium orthophosphate elements proved to possess very stable efficiency and sensing capability when subjected to high temperature. The results are very encouraging for proceeding with development of phased array probes using gallium orthophosphate, for inspection and condition monitoring of high temperature pipelines in power plants at a temperature up to 580°C