Artificial roughness applied to a Solar Air Heater (SAH) absorber plate is a popular technique for increasing its total thermal efficiency (ηt−th). In this paper, the influence of geometrical parameters of V-down ribs attached below the corrugated absorbing plate of a SAH on the ηt−th was examined. The impacts of key roughness parameters, including relative pitch p/e (6–12), relative height e/D (0.019–0.043), angles of attack α (30–75°), and Re (1000–20,000), were examined under real weather conditions. The SAH ηt−th roughened by V-down ribs was predicted using an in-house developed conjugate heat-transfer numerical model. The maximum SAH ηt−th was shown to be 78.8% as predicted under the steady-state condition

Effect of Using Computer in Getting and Remaining Information at Students of First Stage in Biology Subject MIAAD NATHIM RASHEED LECTURER Abstract The recent research goal is to know the influence of computer use to earn and fulfillment information for students of first class in biology material and to achieve that put many of the zeroing hypothesis by researcher as follow: There were no differences between statistical signs at level (0,05) between the average students' marks who they were study by using computer and between the average student ' marks who they were study in classical method of earning and fulfillment. The researcher chose the intentional of the medical technical institute that included of two branches the first class (A

The aim of the present work is to develop a new class of natural fillers based polymer composites with sawdust (S.D) which used two particle sizes (1.2 μm & 2.3 μm) and different weight percentage from sawdust (10%, 15%, and 20%). The mechanical properties studied include hardness (shore D) for all samples at normal conditions (N.C). The unsaturated polyester (UPE) and its composites samples were immersed in water for  30 days to find the effect of particle size of sawdust (S.D) on the weight gain (Mt %) by water for all the samples, also to find the effect of water on their hardness. The results show that the composite materials of sawdust (S.D) fillers which has particle size (1.2 μm) better than (2.3 μm) particle size bef

The calculation of the charge on an isolated dust grain immersed in plasma with different grain sizes is a challenging one, especially under moderately high plasma temperature when secondary electron emission significant. The discrete charging model is used to calculate the charges of dust grain in dusty plasma. In this model, we included the effect of grain size dependence on secondary electron emission. The results show that the secondary electron emission from the glass dust grains due to energetic electron (40eV) can lead to the small grain to be slightly more positive than the large grain. Under these conditions, the smaller and larger grains would be attracted rather than repelled, which possibly lead to enhanced coagulation rates.

Background: Dental implant is one of the most important options for teeth replacement. In two stage implant surgery, a few options could be used for uncovering implants, scalpel and laser are both considered as effective methods for this purpose. The Aim of the study: To compare soft tissue laser and scalpel for exposing implant in 2nd stage surgery in terms of the need for anesthesia, duration of procedure and pain level assessment at day 1 and day 7 post operatively using visual analogue scale . Materials and methods: Ten patients who received bilateral implants participated after healing period completed, gingival depth over each implant was recorded and then implant(s) were exposed by either scalpel or laser with determination for th

The problem of the research is indicated by answering the following questions: 1) what are the attitudes of the Arabic language teachers towards homework?

2) Do the Arabic language teachers differ in their attitudes towards homework according to their specialization? 3) Do the Arabic language teachers differ in their attitudes towards homework according to their gender (male and female)? According to the three questions asked above, we may state the following hypotheses. There is no statistically significant difference between the average of the marks of Arabic language teachers in the real practice of the scale of the attitudes towards their homework and their average in the hypothetical practice of the

This research aims to numerous risks to the portfolio of the insurance company that arise from practicing the activity in general, and the risks arising from insurance contracts in particular, and what is the role of the company in the disclosure to help users (such as owners) to understand and concentration of risks in the financial reporting and identifying movable risks size to reinsurers that may affect the solvency of the portfolio and makes them at a given moment required to fulfill the obligations towards policyholders outweigh the financial capacity, which leads to stumble or bankruptcy.

So I sought this research is to identify the extent of the obligation to disclose the accounting for this risk and the extent of their i

There is no doubt that the field of education and teaching (in any country and whatever its ruling system varies “d”) is considered one of the most specific and sensitive field, because it is related to the building of human. And as the human is a purpose (aim) and the means in the same time and he is the strategist capital, so he way of his rearing, education, choosing the educator, methods of working and the aims are considered serious matters.

     The educational process has aim determined by the society for him self through its working establishments in this field and these are the official and public establishments. And as he feels that the establishments have failed to achieve its d

Background: Premature infant born with immature body system, their organs are not ready for extra uterine life, and they are unable to deal with external stress, which could alter body functions such as cardio-respiratory function. In addition, poor muscle tone increases the chance of developing an abnormal posture. To reduce this instability, applying developmental care such as nesting is vital to promote cardio-respiratory stability, maintain position, and reduce stress in preterm.      Objectives: The study aims to assess the impact of the nesting technique on preterm cardio-respiratory parameters in various positions (supine, prone, and right lateral).       Methodology: The research used randomized controlled trial des