The design, construction and investigation of experimental study of two compound parabolic concentrators (CPCs) with tubular absorber have been presented. The performance of CPCs have been evaluated by using outdoor experimental measurements including the instantaneous thermal efficiency. The two CPCs are tested instantly by holding them on a common structure. Many tests are conducted in the present work by truncating one of them in three different levels. For each truncation the acceptance half angle (θc) was changed. Geometrically, the acceptance half angle for standard CPC is (26o). For the truncation levels for the other CPC 1, 2 and 3 the acceptance half angle were 20o, 26o and 59o, consequently. A significant difference between the instantaneous thermal efficiency of 3.86× CPC (θc=20o) and 2.32× CPC (θc=26o), and between that for 3.61× CPC (θc=26o) and 2.32× CPC (θc=26o). It's noticed that the difference between the instantaneous thermal efficiency of 2.32× CPC (θc=59o) and 2.32× CPC (θc=26o) is small compared with the difference of the first and second cases, the instantaneous thermal efficiency of 2.32× CPC (26o) was higher than those for other three CPCs. The experimental results show that the maximum thermal efficiency of the full 2.32×CPC (26o) is 0.708, the maximum thermal efficiency of the 3.93×CPC (15o), when it's truncated to 3.84× CPC (20o), 3.61× CPC (26o) and 2.32× CPC (59o) are 0.51, 0.52 and 0.66, respectively. As the concentration ratio decreases from (3.93× to 1×), the thermal efficiency, energy losses and optical efficiency increase from (0.47 to 63), (1.58 to 7.2 K.m2/W) and (0.494 to 0.797), respectively.
One of the unique properties of laser heating applications is its powerful ability for precise pouring of energy on the needed regions in heat treatment applications. The rapid rise in temperature at the irradiated region produces a high temperature gradient, which contributes in phase metallurgical changes, inside the volume of the irradiated material. This article presents a comprehensive numerical work for a model based on experimentally laser heated AISI 1110 steel samples. The numerical investigation is based on the finite element method (FEM) taking in consideration the temperature dependent material properties to predict the temperature distribution within the irradiated material volume. The finite element analysis (FEA) was carried
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Objective: To determine the prevalence of Posttraumatic Stress Disorder (PTSD) among Iraqi repatriated
prisoners of Iran-Iraq war, and the relationship with demographic factors.
Methodology: A descriptive study was carried out from Oct. 18th, 2009 through Jan. 10th, 2010. A nonprobability
based snowball sampling technique was used to recruit 92 Iraqi repatriated prisoners of war
(IRPOWs) who had visited Ministry of Human Rights. A data collection instrument was constructed that
consisted of six demographic characteristics, and eight items to measure the level of PTSD in POWs. Data were
collected with the constructed instrument during a brief interview. Data were analyzed through the application of
descriptive statist
In this study, the spreading of the pandemic coronavirus disease (COVID-19) is formulated mathematically. The objective of this study is to stop or slow the spread of COVID-19. In fact, to stop the spread of COVID-19, the vaccine of the disease is needed. However, in the absence of the vaccine, people must have to obey curfew and social distancing and follow the media alert coverage rule. In order to maintain these alternative factors, we must obey the modeling rule. Therefore, the impact of curfew, media alert coverage, and social distance between the individuals on the outbreak of disease is considered. Five ordinary differential equations of the first-order are used to represent the model. The solution properties of the system ar
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ABSTRACT The role of specific amino acids namely cysteine, methionine, threonine and asparagine in the protection provided by vamin solution against B-lactam inhibition to E. coli was evaluated in vitro. In minimal medium, Cells were treated with 32 ug/ml of penicillin G, carbencillin, hostacillin, cloxacillin and cephalotin in the presence of specific amino acid supplementations. Deletion of specific amino acids from the media abolished the protection provided by vamin. Threonine was essential for the protection of cells against all tested antibiotics, while cysteine was essential for protection against carbencillin and cephalotin Deletion of methionine or asparagine abolished the protec- tion against carbencillin and to a less extent ce
... Show MoreThe morphometric parameters of Acinopus (Acinopus) laevigatus Ménétriés, 1832 (Coleoptera, Carabidae) were studied and their altitudinal variability was assessed. The length of head is the most variable, and the smallest value of the coefficient of variation is observed for the width of elytra. The length of body parts (head, pronotum, elytra) were more variable compared to their width. The correlation relationship between the morphometric parameters of different parts of the body was analyzed. A high correlation was found between the elytra length (EL) and the total body length (BL) (r=0.93), and the lowest correlation was found between the elytra width (EW) and the pronotum length (PL) (r=0.57). According to all measurement indicato
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This study conducts a systematic comparative critical discourse analysis of news reports from prominent American (CNN) and Russian (RT) media sources covering the Russia-Ukraine conflict. Utilizing the theoretical frameworks of Norman Fairclough's multidimensional model and Teun van Dijk's socio-cognitive approach, the research examines the underlying ideological assumptions and discursive strategies employed by the two contrasting news channels. Quantitative analysis of discursive techniques and linguistic features provides insights into how each channel selectively utilizes language to convey distinct ideological positions. The findings demonstrate how media discourse constructs and normalizes particular ideological representations of pol
... Show MoreThe present research aims to identify thecorrelation between cognitive motivation andthe trend towards the teaching profession among students of the Department of Chemistry in theFaculty of Education for Pure Sciences - Ibn al-Haytham, as well as to identify the differences in the relationship according to the variable type (male, female). The measures of cognitive motivation and the trend towards the teaching profession were applied, using pearson's correlation coefficient,t-testfor one sample, andthe t-test of two separate samples.
Abstract
The research aimed to test the relationship between the size of investment allocations in the agricultural sector in Iraq and their determinants using the Ordinary Least Squares (OLS) method compared to the Error Correction Model (ECM) approach. The time series data for the period from 1990 to 2021 was utilized. The analysis showed that the estimates obtained using the ECM were more accurate and significant than those obtained using the OLS method. Johansen's test indicated the presence of a long-term equilibrium relationship between the size of investment allocations and their determinants. The results of th
... Show MoreThe research gets its importance through the importance of the annual regulations in the taxation accounting and its efficiency to fulfill accounting justice under the effect of the financial changes and the truth of the activity of the taxable businesses .This through the problem of the research which is found in many objections about taxation accounting according to the annual regulations issued by the General Commission of Taxes , Their aim is to get the real benefits and to decrease the difference in opinions during the estimation to fulfill justice in distributing the burden of taxation .
The research expose many conclusions and recommendations namely , the taxation justice fulfillment is not only in justic
... Show MoreThe tourism industry has undergone exponential transformation, reshaped by online travel agencies (OTAs), shifting consumer preferences, and technological advancements. Established OTAs like TripAdvisor and Travelocity face pressures to adapt their strategies to capitalize on these disruptive landscape changes. This research involves a comparative analysis examining the key challenges confronting TripAdvisor and Travelocity, with a focus on opportunities to leverage artificial intelligence (AI) in enhancing personalization and the traveler experience. The study utilizes publicly available data on the companies and academic literature on AI innovation diffusion. Findings reveal that while TripAdvisor has actively developed AI-based trip plan
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