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.
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Agricultural lands have great importance in people's lives, and their exploitation has a great impact on strengthening the national economy. Therefore, countries have given great importance to this sector, and because of the importance of this sector, the state has given large areas of these lands to the farmers to invest in agriculture, and among these farmers are those who died and left behind children who took up crafts. Agriculture, for fear that these agricultural lands would be abandoned and turned into waste lands, a land system was introduced called (regular distribu- tion), which corresponds to (legitimate inheritance). Under this system, these lands were trans- ferred to the children of farmers who died so that the process of inve
... Show MoreAmino acids have the role in the process of proteins synthesis. They are an essential source of nitrogen atoms that have a role in the pathways of synthetic reaction pathways. The carbon skeletons of the amino acids are the source of energy in addition to their role as precursors in the paths of interactions. The amino acids analysis for the brain of the quail bird in different stage of development (10-16 days of incubation) in addition to the hatching stage (17th day) and the adult. Materials and Methods: Amino Acids Analysis The amino acids were separated from the embryos and adult brains of the quail bird Coturnix coturnix and were diagnosed based on standard amino acids, using high performance liquid chromatographic device (H.P.L.C.). R
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The settlement rate and pore water pressure dissipation rate are mainly controlled by the permeability of soil. Both laboratory and field tests show that the permeability is varied during the loading and consolidation process. It is known that consolidation process is accompanied by decrease in void ratio which leads to decrease in the coefficient of permeability. The importance of the decrease of the coefficient of permeability on the time rate of settlement and pore water pressure needs to be investigated.
This paper takes into account the change in coefficient of permeability during consolidation and studies its effect on consolidation characteristics of a clay layer. The finite element method is used in the analysis and the packag
The study aims at identifying the morphological and psycho-socio-economic qualities wished to be in a life partner among a sample of Palestinian youth. The total sample was (231) and consisted of (83) male and (148) female students. Each student presented a detailed report on the qualities he/she wished to be in life partner. The study used the descriptive approach and content analysis method. The validity and stability of the analysis were calculated. The results showed eight qualities in both groups: physical, psychological, emotional, social, intellectual, familial, economic and academic. Female students were found to have more variations than male students in terms of the qualities preferable in the life partner. Male students
... Show MoreThe study aimed to know the effect of the use alcoholic ethanol extraction of Boswellia Carterii In prolonging the period of preservation cooled ground meat in 4C for 6 days, it has been mixing ground meat with 150,300,450 mg/ml of alcoholic extract Consecutive, Where (0 was the control sample), All samples were stored separately for 0 , 3 , 6 days in Refrigerator temperature 4 C, Conducted by some microbial tests, Results have shown that mixing the ground meat with Boswellia Carterii extraction Led to prolong the storage of meat for 6 days at 4 C .and the Best result came when adding alcoholic ethanol extract of Boswellia Carterii by 450mg/ml Which Equal 0.9 g ,that reducing microbial load more higher than 150&300 mg/ml. All of thes
... Show MoreThis research studies the effect of grain size for the final stage in sintering Al2O3 .The experimental results for α- Al2O3 powder are modeled using ( L2-Regression ) technique in order to study the effect grain size distribution on densification rate using four kinds for the initial particle size which were ( 1.44 , 2.54 , 0.7-2.54 ,1.15-3.53 ) µm , and for sintering time (0-241) min. The mathematical simulation for grain size changing shows that the densification rates boots up as the grain size goes lower, this was due to the increase of contact area between the grains.
Cleft / palate is one of the common congenital deformities in craniofacial region, associated with different types of dental anomalies like (Tooth agenesis, impaction, and supernumerary teeth) with marked changes in palatal dimensions. This study aimed to determine the prevalence of teeth agenesis and dental anomalies in cleft lip/palate patients using CBCT, and to compare the palatal dimension of cleft group with control subjects. Twenty-eight cleft cases collected during the period from 2015 to 2022, CBCT images evaluated, the study sample classified into two groups (14 bilateral and 14 unilateral cleft lip/palate) and the non-cleft control group (14 CBCT images). The presence of dental anomalies was assessed in relation to clef
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