In this work, effects of using different evaporative cooling pads (ECPs) on the energetic and exergetic efficiency of a direct evaporative air cooler (DEAC) have been theoretically and experimentally investigated. Three types of ECPs were used, i.e., honeycomb cellulose cooler pad (HCCP), shading-cloth cooler pad (SCCP), and aspen wood wool cooler pad (AWWCP). For SCCP and AWWCP, a 3-cm pad thickness was used, while for the HCCP, three different values of pad thickness were used, i.e., 3, 5, and 7 cm. Tests were carried out using air velocities of 8, 14, and 19 m/s, measured at the DEAC outlet. Engineering equation solver (EES) used for performing the required calculations of the various parameters affecting the thermal performance of the DEAC, i.e., dry bulb temperature at exit (Tdb), relative humidity at exit (RHo), mass of water evaporated, saturation efficiency, energetic efficiency (ηen), exergetic efficiency (ηex), and the overall exergetic efficiency (ηex). Results showed the great effectiveness of HCCP compared to the other studied types. HCCP showed the highest energetic efficiency reached 103 % for 3 cm thickness of the ECP, and the highest exergetic efficiency of about 19 %.
An experimental investigation of natural convection heat transfer from an isothermal horizontal,vertical and inclined heated square flat plates with and without circular hole, were carried out in two cases, perforated plates without an impermeable adiabatic hole "open core" and perforated plates with an impermeable adiabatic hole "closed core" by adiabatic plug. The experiments covered the laminar region with a range of Rayleih number of (1.11x106 ≤RaLo≤4.39x106 ), at Prandtle number (Pr=0.7). Practical experiments have been done with variable inclination angles from horizon (Ф=0o ,45o,90o,135oand 180o),facing upward (0o≤Ф<90o), and downward (90o
≤Ф<180o). The results showed that the temperature gradient increases whi
The study aims at measuring the dimensions of binding and non-binding social responsibility and its relation to the organizational performance in telecommunication companies in the Republic of Yemen using analytical descriptive approach and questionnaire as a main tool for data collection and comprehensive inventory method.
It has been found that there is a positive effect and significant moral relation between social responsibility with its binding and non-binding dimensions and the organizational performance of telecommunication companies in the Republic of Yemen at a level of significance below (0.05). It has also been found that the correlation between the non-binding social responsibilit
... Show MoreThe research aims at considering the reality of cognitive bias and organizational inertia as determinants of strategic change in a sample of companies listed in Amman Stock Market. To achieve objectives of the research, a model consisting of two independent variables has been designed, namely:
(1) The cognitive bias resulting from (escalating commitment, analogy, previous assumptions, representative generalization, command and control, convergent thinking), and (2) Organizational inertia due to (Icarus discrepancy, power distribution, rooted organizational culture), and a dependent variable, strategic change in (leadership patterns, strategy, the organization per se).
From the model two main hypotheses were derived;
... Show MoreContamination of surface and groundwater with excessive concentrations of fluoride is of significant health hazard. Adsorption of fluoride onto waste materials of no economic value could be a potential approach for the treatment of fluoride-bearing water. This experimental and modeling study was devoted to investigate for the first the fluoride removal using unmodified waste granular brick (WGB) in a fixed bed running in continuous mode. Characterization of WGB was carried out by FT-IR, SEM, and EDX analysis. The batch mode experiments showed that they were affected by several parameters including contact time, initial pH, and sorbent dosage. The best values of these parameters that provided maximum removal percent (82%) with the in
... Show MoreNon-orthogonal Multiple Access (NOMA) is a multiple-access technique allowing multiusers to share the same communication resources, increasing spectral efficiency and throughput. NOMA has been shown to provide significant performance gains over orthogonal multiple access (OMA) regarding spectral efficiency and throughput. In this paper, two scenarios of NOMA are analyzed and simulated, involving two users and multiple users (four users) to evaluate NOMA's performance. The simulated results indicate that the achievable sum rate for the two users’ scenarios is 16.7 (bps/Hz), while for the multi-users scenario is 20.69 (bps/Hz) at transmitted power of 25 dBm. The BER for two users’ scenarios is 0.004202 and 0.001564 for
... Show MoreThe game of volleyball is one of the competitive team games that took the lead in terms of its spread in the world, and the game of volleyball relies on basic skills as an important base on which this game is built to advance in the level of performance Performance and among these skills the skill of spiking and blocking wall, the research aims to identify the extent of the relationship of decision-making to the performance of spiking and blocking in volleyball for junior players. The sample was chosen from volleyball players for the Junior Specialized School of Sulaikh Sports Club / Baghdad Governorate for the season 2020 The researcher used the descriptive approach, and the research community was composed of (101) players. The two
... Show MoreImportance of accounting standards belong to be the instructor and the advisor for accountant in performing his work . For each invironment a group of political, social, economical and cultural factors which distinguish it about other environments . In order to perform its aim in produsing accouting information helps in making decisions on different levels, accounting standards should established in a form that harmonized with the environment that apply in it . Establishing international accounting standards comes with the same direction and then it has put influential with standards some states that have influence on international accounting standards committee. So because of the big changes that happened in the inte
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