A linear algebraic approach in analyzing the M/GE/1 and GE/M/1 queuing systems at equilibrium

Uses the algebraic approach in the queuing theory to derive the M/G/1 equilibrium solution for the number of jobs in the system when the probability distribution function representing the general distribution is the generalized exponential (GE-type). Similarly the GE/M/1 system is solved. Furthermore, it has been shown that as expected the solutions are equivalent to the maximum entropy solutions of the M/G/1 and G/M/1 systems respectively at equilibrium

Theory of Constraints in Construction Projects

تعاني المشاريع الانشائية في العراق من القيود (الاقتصادية والتقنية والسياسية والقانونية والبيئية) التي تعوق عملها لذا من الضروري تحديد هذه القيود من خلال إتباع النظريات من أجل تحديدها بدقة وتوفير معلومات مفيدة لاتخاذ قرارات حول قيود الإنتاج وتأثيرها على العمل، يعرف القيد بأنه: أي محدد يمنع المشروع من تحقيق أهدافه أو تحقيق مستوى من الأداء بالنسبة لهذا الهدف، لذا لا بد من استخدام بعض النظريات، بما في ذلك نظريات القيود التي تحدد لها وإيجاد حلول لتلك العقبات من خلال مخططات منهج التفكير. وتعرف نظرية القيود: بأنها "فلسفة إدارية شاملة تهدف إلى تحقيق مستمر لأكثر من هدف واحد في المشروع. فإذا كان المشروع يعمل على تحقيق إنجاز معين في مشروع ما ،بعد تحديد القيود وأنواعها وكل حسب مدى اهميته وتأثيره سوف يتم ايجاد الحلول لها بواسطة "منهج ألتفكير" الذي يعرف بأنه : يوفر اطار متكامل لإلية عمل المشاريع اذ يساعد على تحديد ومعالجة المعوقات التي تعاني منها المشاريع والعمل على تحديد الحلول الملائمة وذلك من خلال مجموعة من مخططات التفكير المنطقية التي تبدأ بدراسة واقع الحالي للمشروع الذي يعاني من المعوقات ومن ثم البحث عن مجموعة المعوقات التي تعانيها ويتم ترتيب المعوقات بحسب اهميتها ومدى ارتباطها ببعض وذلك من أجل تحديد المشاكل الجوهرية التي تسبب في حدوث الواقع غير المرغوب، يتم بعد ذلك تقديم مجموعة من الحلول المقترحة ويتم دراسة هذه الحلول وبيان النتائج المستقبلية لكل حل وفائدته في معالجة المشكلة المحددة ومدى الأثر المستقبلي لتطبيقه، اذ ستتمثل المنهجية المستخدمة في البحث في استخراج المؤشرات من الإطار النظري والعملي وإيجاد الحلول من خلال مخطط منهج التفكير للخروج بعدد من الاستنتاجات والتوصيات الرامية إلى تحقيق أهداف البحث.Construction projects in Iraq are suffering from constraints (financial, technical, political, legal and environmental) that hamper their work. It is therefore necessary to identify these constraints by following the theories in order to accurately identify and provide useful information to make decisions about production constraints and their impact on work. To achieve its objectives or achieve a level of performance for this goal, so it is necessary to use some theories, including theories of constraints that identify those obstacles and find solutions to those obstacles through the schemes of thinking. The concept of constraints is defined as "a comprehensive management philosophy that aims to achieve a continuous achievement of more than one goal in a project." If the project works to achieve a certain achievement in a project after defining the constraints and types and each according to its importance and impact, Which provides a comprehensive framework for the work of projects, as it helps to identify and treat the obstacles experienced by the projects and work to identify appropriate solutions and through a set of logical thinking throughput that begin studying the current reality of the project that suffers from the obstacles and then search for  Constraints A number of proposed solutions are then presented. These solutions are examined and the future results of each solution are identified and useful in addressing the specific problem and the extent of the future impact of its application. The methodology used in the research of extracting indicators from the theoretical and practical framework and finding solutions through the curriculum of the thinking throughput will be used to reach a number of conclusions and recommendations aimed at achieving its objective

Study the Effect of Silica Gel Powder on Clathrate Hydrate Formation Behavior for HFC-134a Gas.

الكلاثريت هيدرات عبارة عن جزيئات معقدة تتكون من الاتصال بين الماء والغاز عند الضغط العالي ودرجات الحرارة المنخفضة. أحد الأهداف الهامة لتكنولوجيا هيدرات الغاز هو تعزيز تكوين الهيدرات أو تقليل وقت التنوي لتشكيل الكلاثريت . تم دراسة تأثير مسحوق هلام السيليكا كمحفز على تركيبة هيدرات الغاز R-134a في تجربة نظام ايزوكوريك (حجم ثابت). من الملاحظ أن للوسط المسامي  تأثير كبير في زيادة سرعة التنوي وكذلك تحسين نمو الهيدرات. في التجربة ، تمت دراسة تأثير مسحوق هلام السيليكا لتحديد تأثيرها على تكوين وتبريد 134 هيدرات  و تم الحصول على العديد من الوظائف الموضوعية من النماذج الحركية مثل كمية الغاز المستهلكة (∆n) ومعدل النمو (r (t)) وثابت المعدل الظاهري (Kapp) وتحويل الماء إلى هيدرات. ازدادت كمية الغاز المستهلكة (∆n) في النظام الثنائي مع زيادة الضغط الأولي لتكوين الهيدرات ، وأيضا معدل نمو الهيدرات (r (t)) وزيادة تحويل الماء لزيادة الهيدرات عندما تكون هذه هي المرة الأولى التي يؤثر فيها مسحوق هلام السيليكا. على هذه الوظائف  بمتوسط ​​ حجم  نشط (900) نانومتر ، مساحة سطح (0.65) م 2 / جم ، حجم المسام 210.85 سم 3 / جم ومتوسط ​​حجم المسام (900) نانومتر الذي درس للاستخدام في التطبيقات الصناعية ومعالجة المياه. بإضافة مسحوق هلام السيليكا يتحسين نمو الهيدرات و   ذلك لانه يزيد من ذوبان غاز الهيدرات ويقلل من زاوية التلامس. بالإضافة إلى ذلك ، مسحوق هلام السيليكا يؤثر بشكل إيجابي على الاتصال الماء مع الغاز من خلال زيادة سطح التفاعل بين الغاز والماء وهذا يزيد من معدل تكوين الهيدرات.One of the important aims of gas hydrate technology is to enhance the formation of hydrate or reduction the induction time for clathrate formation. The effect of the different promoter silica gel powder on R-134a gas hydrate formation has been investigated in the isochoric system experiment. It is noted that the purse media have a significant effect in increasing the speed of nucleation as well as improving the growth of hydrate. In the experiment, the effect of silica gel powder was studied to determine their effect on the composition and cooling capacity of 134 hydrates. From kinetic models were obtained many objective functions such as the amount of gas consumed (∆n), the growth rate (r (t)), and conversion of the water to hydrate. The gas consumed (∆n) of binary system increased with increase initial pressure of hydrate formation, also the hydrate growth rate (r (t)) and increase conversion of water to hydrate increase  when this the first time that the effect of silica gel pweder on these functions with average active size (900) nm, BET surface area (0.65) m2/g, pore volume 210.85 cm3/g and average pore size (900) nm that studied for use in industrial applications and water treatment. The improvement of hydrate growth is marked by the addition of silica gel powder, which in turn increase the solubility of hydrate gas and reduce the contact angle. In addition,   silica gel powder positively the contact with the gas through the increase of the interaction surface between gas and water and this increases the rate of formation of hydrate

Proposing a General Formula for Evaluating the Parametric Cost Using MLR Method

This research takes up address the practical side by taking case studies for construction projects that include the various Iraqi governorates, as it includes conducting a field survey to identify the impact of parametric costs on construction projects and compare them with what was reached during the analysis and the extent of their validity and accuracy, as well as adopting the approach of personal interviews to know the reality of the state of construction projects. The results showed, after comparing field data and its measurement in construction projects for the sectors (public and private), the correlation between the expected and actual cost change was (97.8%), and this means that the data can be adopted in the research study of the integration of parametric costs in a predictive model for future study. Changes in the parametric costs of construction projects substantially impact their time, cost, and quality and are a major barrier to their execution, necessitating research, analysis, and the development of the most effective solutions. The study aims to identify the parametric cost accurately through iterative tests and continuous improvements by presenting literature describing the history and characteristics of the parametric cost methodologies and identifying each methodology's limitations, strengths, and weaknesses to promote a better understanding of their best practices and use for managing project cos

Using Microbial Desalination Cell to Treat Iraqi Wastewater

A Three-chambers MDC was made using three identical cubicalplexi-glass sections. Each chamber has an effective volume of 35 cm3. An anionexchange membrane (AEM) was used to separate the anode from thedesalination chambers while a cation exchange membrane (CEM) was used toseparate the cathode from the desalination chambers. Two graphite sheets wereused as anode and cathode electrodes. Biotic experiments have included aircathode MDC fed with synthetic municipal wastewater, Bio-cathode MDC inwhich the cathode chamber was inoculated with microalgae as an oxygensource and air-cathode MDC was fed with floated oil layer in the anodechamber as an organic source. Maximum power density obtained from theMDC was 121 mW/m2. The corresponding current density was 410 mA/m2.Maximum power density obtained in this study was in consistency with thatpresented in previous studies. Maximum coulombic efficiency and chargeefficiency achieved were 9% and 165% respectively. The results of this studyconfirmed the validity of using MDC technology to treat municipal wastewateras well as oil, desalinate brackish water and generate electric powersimultaneously. Moreover, the results revealed the possibility of using mixedculture algae, available in the Iraqi environment, in the cathode chamber as anoxygen source to develop more energy efficient MDC. Further study deals withdifferent system configurations and different operating conditions are needed

Impedance studies on Ca0.5Sr0.5Cu3Ti4O12 ceramic oxide

Ca0.5Sr0.5Cu3Ti4O12 (CSCTO) ceramic oxide was prepared using solid state reaction technique. Impedance measurement was done using High Dielectric Resolution Analyzer (Novocontrol Novotherm) from 30°C to 250°C, in the frequency range of 10-2 to 106 Hz. X-ray diffraction pattern showed a single phase with a cubic structure. In the complex impedance plot, three semi-circles were observed; these represented the grain, grain boundary and electrode effect responses. The semi-circles were fitted using a series network of three parallel RC circuits. The resistance was found to increase with the decreasing temperature. The activation energies, E a, obtained from the Arrhenius plots of CSCTO, were 0.31 eV and 0.73 eV for grain and grain boundary conductivity, respectively. The value of the grain energy was revealed as smaller than the grain boundary energy, due to the semi-conducting grain and the insulating grain boundary characteristic (Sinclair et al., 2002)

Immunohistochemical, histological and ultrastructural evaluation of protection provided by cholera vaccine against V. cholerae O139

In our previous study, complete protection was observed in rabbit immunized with 1 × 1010 CFU of live attenuated VCUSM21P vaccine against challenge with 1 × 109 CFU Vibrio cholerae O139. In the present study, we investigated whether the vaccines can effectively protect immunized animals from any pathologic changes using histological, immunohistochemical and ultrastructural techniques. Severe pathology is evident in wild type injected ileum in non-immunized, showing extensive villous destruction, edema, necrosis and inflammation with infiltration of large numbers of inflammatory cells, extensive damage to the villi and microvilli with pore formation. Histology of ileum injected with wild type in immunized rabbit shows no significant pathological changes except for a few inflammatory cells in lamina propria with mild edema in mucosa and submucosa. immunohistochemical staining revealed O139 antigens of wild type are seen in the lamina propria of edematous villi, muscularis mucosa and submucosa with weak presence in the muscle coat in non-immunized rabbit after challenged with wild type in non-immunized rabbits, but in immunized rabbit localisation of the O139 LPS antigen is seen at the tips of the intact villi, within lamina propria and muscularis mucosa only. These observations suggest that the vaccine can effectively protect animals from any pathologic changes and eliminate V. cholerae O139 from the immunized animals

Ac conductivity of Ca1-xAxCu3Ti4O12 (A=Sr or Ba) with x=0.0 and 0.2 ceramics

Colossal dielectric constant materials such CaCu3Ti4O12 (CCTO) have recently received an enormous of attention because of their potential in technological applications due to the formation of internal barrier layer capacitor (IBLC) contains semiconducting grains with insulating grain boundaries. Ca1-xSrxCu3Ti4O12(CSCTO) and Ca1-xBaxCu3Ti4O12 (CBCTO) with x = 0.0 and 0.2 ceramics has been doped on Ca site with strontium or barium was prepared using solid state reaction technique. X-ray diffraction pattern shows single phase with cubic structure. In complex impedance plot for both the ceramics show three semicircular arcs re present the grain, the grain boundary and electrode effect responses and modeled using series network of three parallel RC circuits. Two regions were found in conductiv ity plot due to the grain boundary at low frequencies and the grain at high frequencies. The n value obtained from the fitting at the grain region at high frequency dependent are above 0.6 indicates of electron hopping conduction mechanism among Ti 3+and Ti4+. The activation energy values for CCTO are 0.28 eV and 0.74 eV for grain and grain boundary regions, respectively while for CSCTO the energies is 0.27 eVand 0.71 and for CBCTO is 0.31 eV and 0.59 eV for the grain and grain boundary regions respectively