In this work, results of a mathematical analysis of the role of workpiece preheating in laser keyhole welding were presented. This analysis considered the steady-state welding as well as certain range of boundary conditions over which preheating effect would be indicated. This work is an attempt to interpret the role of preheating to increase welding depth and perform keyhole welding with high quality using physical and thermal properties of steel alloys.
Most of World nations are striving to provide the necessary needs to protect their economic properties assets against natural or abnormal disasters that may be inflicted on such property and the means that used by such countries to reduce the damages is insurance, whereas insurance as a system that collects and distributes different risks into the group thus to achieve a social symbiosis between individuals. The system works to transfer the risks from the individual to the group and then distributes the losses to all members of the group.
According to the importance of the insurance sector and the need to develop it as well as working on improving its performance, this search aims to identify the ac
... Show MoreThe study aimed to determine the impact of energy for the north and south magnetic poles on the the growth of bacteria isolated from cases of tooth decay, 68 swabs were collected from surfaces of faulty tooth, the detected of Staphylococcus aureus
... Show MoreThe Study addressed the effectiveness of dialogic communication in online public relations with an audience of higher education institutions in the United Arab Emirates. The study aimed to know about the interest extent of higher education institutions through their websites with the elements of dialogic communication in online public relations to communicate with their audience. The researcher used survey methodology and content Analysis tool as an essential tool for collecting information. Some of the important results of the study are: The websites of higher education institutions in terms of indicators of ease of use; the main links on the websites are clearly available on the opening page, there is a map on the websites, reduce depe
... Show MoreIn this study, mesoporous silica (MPS) is made using the sol-gel method from a cheap source (Na2SiO3) using the surfactant hydroxycetyl hydroxyethyl dimonium chloride as a template. The task is the adsorption-based removal of the medication metoprolol (MP) at concentrations between 10 and 50 ppm. Variables such as: contact time, dose of adsorbent, starting concentration of adsorbate, and adsorption temperature were studied which show the equilibrium time and adsorbent dose are 40 min and 0.05 g respectively. The Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherm models were fitted to the data obtained from the experiments. Comparing the outcomes showed that, of the four investigated isotherm models, the Freundlich equation m
... Show MoreElectrochemical Grinding (ECG) process is a mechanically assisted electrochemical process for material processing. The process is able to successfully machine electrically conducting harder materials at faster rate with improved surface finish and dimensional control. This research studies the effect of applied current, electrolyte concentration, spindle speed and the gap between workpiece and tool on hardness and material removal rate during electrochemical grinding for stainless steel 316. The characteristic features of the electrochemical grinding process are explored through Taguchi-design-based experimental studies. The better hardness can be obtained at 10 A of the current, 150 g/l of the electrolyte concentration, 0.3 mm of gap an
... Show MoreThe study aimed to investigate the effect of fungicides chlorothalonil at different concentrations ( 0.1 , 0.5 , 5 , 25 , 50 ) × 10 - 5 M on some cytogenetic parameters of human peripheral blood lymphocytes . The genotoxicity parameters were estimated by the number of chromosomal aberrations (CAs) and their types and by estimating the induced micronuclei (Mn) . Cytotoxic effect recorded by estimating the mitotic index (MI) . Results revealed that the fungicide increased the CAs in dose – response pattern with positive correlation coefficient ( r = + 0.964) , there was a significant differences among the concentrations (P<0.01) . The major CAs records chromosomal breakage at concentrations. 0.5 , 5 , 25 , and 50 , while the lowest concen
... Show MorePbxCd1-xSe compound with different Pb percentage (i.e. X=0,
0.025, 0.050, 0.075, and 0.1) were prepared successfully. Thin films
were deposited by thermal evaporation on glass substrates at film
thickness (126) nm. The optical measurements indicated that
PbxCd1-xSe films have direct optical energy gap. The value of the
energy gap decreases with the increase of Pb content from 1.78 eV to
1.49 eV.
A simplified theoretical comparison of the hydrogen chloride (HCl) and hydrogen fluoride (HF) chemical lasers is presented by using computer program. The program is able to predict quantitative variations of the laser characteristics as a function of rotational and vibrational quantum number. Lasing is assumed to occur in a Fabry-Perot cavity on vibration-rotation transitions between two vibrational levels of hypothetical diatomic molecule. This study include a comprehensive parametric analysis that indicates that the large rotational constant of HF laser in comparison with HCl laser makes it relatively easy to satisfy the partial inversion criterion. The results of this computer program proved their credibility when compared with th
... Show MoreThe effect of air injection angle on the performance of airlift pump used for water pumping has been studied analytically and experimentally. An airlift pump of dimensions 42mm diameter and 2200 mm length with conventional and modified air injection device was considered. A modification on conventional injection device (normal air-jacket type) was carried out by changing injection angle from 90 (for conventional) to 45 and 22.5 (for modified). Continuity and one-dimensional momentum balance for the flow field with basic principle of two-phase flow and expressions of slip ratio and friction factor as function of flow rates were formulated. The analytical and experimental investigations were carried out f
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