346 research outputs found
Passive Design of Buildings for Extreme Weather Environment
Buildings account for nearly 40% of the end-use energy consumption and carbon emissions globally. Buildings, once built, are used at least for several decades. The building sector therefore holds a significant responsibility for implementing strategies to increase energy efficiency and reduce carbon emissions and thus contribute to global efforts directed toward mitigating the adverse effects of climate change. The work presented in this paper is a part of continuing efforts to identify, analyze and promote the design of low energy, sustainable buildings with special reference to the Kazakhstan locality. Demonstration of improved environmental conditions and impact on energy savings will be outlined through a case study incorporating a passive design approach and detailed computational fluid dynamics analysis for an existing building complex. The influence of orientation and configuration is discussed with reference to energy efficiency and associated wind comfort and safety. The effect of these aspects on energy consumption and comfortable wind environment has been assessed using CFD analysis and proved to be affective. Single building and multiple building configurations have been analyzed and compared. According to the findings, multiple building configurations have better wind conditions when compared with a single standing building. With respect to orientation the former one should be modeled with the fully surrounded side of a “box” opposite to the predominant wind direction whereas the latter one should be located with the rear side opposite to the wind direction. Thus, results indicated that there is a considerable influence of passive design and orientation on energy efficiency, wind comfort and safety. Careful consideration and application of the findings can potentially lead to considerable decrease of energy consumption and, therefore, allow saving money and the environment at the same time
Akutna neurotoksičnost acetaminofena u pilića
Acetaminophen is a non-steroidal drug used as an anti-inflammatory, analgesic and antipyretic in humans and animals. In chicks, neurotoxicity associated with acetaminophen has not been fully elucidated. The aim of this study was to identify the neurobehavioral, biochemical and histopathological effects of acetaminophen in 7 day-old broiler chicks. The acute LD50 of acetaminophen was estimated by the up- and- down method, and then the influence of acetaminophen on the open field activity and tonic immobility test was recorded. The behavioral signs and toxicity scores were recorded. The liver enzymes, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities were estimated. Histopathology of the brain and liver were performed. The acetaminophen LD50 value in chicks was 1077 mg/kg, intramuscularly. Acetaminophen reduced the general locomotive activity of the chicks, measured in the open- field arena, as a result of a significant rise in latency in moving from the central square, and a reduction in the numbers of lines crossed as well as reduction in the vocalization score compared to the control. Intramuscular injections of acetaminophen at doses of 500 and 1000 mg/kg induced signs of toxicosis, such as head dropping, closed eyelids, immobility, loss of vocalization, and recumbency, followed by death. Histopathological examination of the brain showed the presence of congestion of blood vessels, vasogenic edema and necrosis of Purkinje cells. Degenerative changes and liver enzyme function showed liver dysfunction. Our results show behavioral, biochemical and histopathological data demonstrating that acetaminophen at high doses produced acute neurotoxicity in chicks.Acetaminofen je nesteroidni lijek koji se upotrebljava kao protuupalno, analgetičko i antipiretičko sredstvo u ljudi i životinja. U pilića nije potpuno poznata povezanost neurotoksičnosti i acetaminofena. Cilj ovog istraživanja bio je identificirati neurobihevioralne, biokemijske i histopatološke učinke acetaminofena u sedmodnevnih brojlera. Akutni LD50 acetaminofena procijenjen je metodom “up and down” nakon čega je zabilježen utjecaj acetaminofena na aktivnost na otvorenom i toničnu nepokretnost. Zabilježeni su bihevioralni znakovi i razina toksičnosti. Izmjerene su vrijednosti jetrenih enzima, aktivnost aspartat-aminotransferaze (AST) i alanin-aminotransferaze (ALT). Učinjena je histopatološka pretraga mozga i jetre. Vrijednost LD50 acetaminofena u pilića bila je 1077 mg/kg, intramuskularno. Acetaminofen je smanjio opću lokomotornu aktivnost i stupanj glasovnog izražavanja pilića na otvorenom prostoru, kao posljedica znakovitog porasta latencije u odnosu na piliće kontrolne skupine. Intramuskularna injekcija acetaminofena u dozama od 500 i 1000 mg/kg izazvala je znakove toksikoze kao što su padanje glave, spušteni kapci, nepokretnost, gubitak glasa, ležeći pložaj te smrt. Histopatološka pretraga mozga pokazala je kongestiju krvnih žila, vazogeni edem i nekrozu Purkinjeovih stanica. Došlo je do degenerativnih promjena i disfunkcije jetre što su pokazali jetreni enzimi. Bihevioralni, biokemijski i histopatološki podaci iz ovog istraživanja pokazali su da acetaminofen u visokim dozama uzrokuje akutnu neurotkosičnost u pilića
Education for development in Iraq with special reference to the diversification of secondary education
While it is true that educating and improving the human skills
in a country can have positive effects on social and economic
development, there are also clear indications that unplanned
expansion of the educational system in a large number of
developing countries has given rise to serious problems in
terms of the supply of technical skills and massive influx of
secondary school graduates into higher education. Therefore
there is an urgent need to restructure the educational system,
especially the secondary education level, to meet the country's
rising demand for a progressive economy and advanced industry,
and to keep it in line with social demand and higher education
capacity. [Continues.
A Review of Preparation and Characterization of Additively Manufactured Stainless Steel
في عالم اليوم، يعد التصنيع بالإضافة طريقة معروفة لإنشاء نماذج ثلاثية الأبعاد، إما من المعادن أو السيراميك أو البلاستيك أو مزيج من هذه المواد. يرتبط التصنيع بالإضافة بسلسلة من دورات التسخين والتبريد السريعة، فضلاً عن التدرجات الكبيرة في درجات الحرارة، مما يؤدي إلى تطوير تواريخ حرارية معقدة، والتي لها تأثير مباشر على الهياكل الدقيقة للمواد الناتجة. نظرًا لطبيعة هذه العملية الديناميكية والبعيدة عن التوازن، تظهر ميزات هيكلية مجهرية مختلفة. على سبيل المثال، من المحتمل أن تحدث تغييرات في خصائص التآكل للفولاذ المقاوم للصدأ المصنوع بتقنية الاضافة، والتي تتمتع بخصائص ميكانيكية فائقة ومقاومة للتآكل عند تصنيعها باستخدام طرق إنتاج أخرى. نظرًا لأن مثل هذه التعديلات غير مفهومة تمامًا في هذا الوقت، فإن التناقضات والاختلافات في الأدبيات المتعلقة بسلوك التآكل للفولاذ المقاوم للصدأ المصنوع مضافا تظهر بانتظام. يعد تحضير وتوصيف الفولاذ المقاوم للصدأ المصنوع مضافًا موضوع هذا العمل، والذي يوفر تقييمًا نقديًا. فيما يتعلق بإنتاج الهياكل المعدنية الضخمة بمعدلات ترسيب عالية وبتكلفة رخيصة، فقد برز التصنيع بالإضافة السلكي كطريقة قابلة للتطبيق. تستعرض هذه المقالة بعض طرق التصنيع بالإضافة المستخدمة في الغالب مع المواد المعدنية مع التركيز على التصنيع بالإضافة السلكي من الفولاذ المقاوم للصدأ.In today's world, ADDITIVE MANUFACTURING (AM) is a well-known method for creating true three-dimensional objects, either out of metals, ceramics, plastics, or a combination of these materials. ADDITIVE MANUFACTURING (AM) is connected with a series of rapid heating and cooling cycles, as well as substantial temperature gradients, which result in the development of complicated thermal histories, which have a direct impact on the resulting microstructures. Due to the nature of this dynamic and far-from-equilibrium process, different microstructural features emerge. For instance, these are likely to induce changes in the corrosion characteristics of ADDITIVE MANUFACTURING (AM) stainless steels, which have superior mechanical properties and corrosion resistance when manufactured using other production methods. Because such modifications are not fully understood at this time, inconsistencies and conflicts in the literature on the corrosion behaviour of ADDITIVE MANUFACTURING (AM) stainless steels are regularly seen. The preparation and characterization of additively made stainless steel is the subject of this work, which provides a critical assessment. In terms of producing huge metallic structures at high deposition rates and cheap costs, WIRE ARC ADDITIVE MANUFACTURING (WAAM) has emerged as a viable method. This article reviews some ADDITIVE MANUFACTURING (AM) methods used mostly with metallic materials focusing on the WIRE ARC ADDITIVE MANUFACTURING (WAAM) of stainless steel
On the Reliability of LTE Random Access: Performance Bounds for Machine-to-Machine Burst Resolution Time
Random Access Channel (RACH) has been identified as one of the major
bottlenecks for accommodating massive number of machine-to-machine (M2M) users
in LTE networks, especially for the case of burst arrival of connection
requests. As a consequence, the burst resolution problem has sparked a large
number of works in the area, analyzing and optimizing the average performance
of RACH. However, the understanding of what are the probabilistic performance
limits of RACH is still missing. To address this limitation, in the paper, we
investigate the reliability of RACH with access class barring (ACB). We model
RACH as a queuing system, and apply stochastic network calculus to derive
probabilistic performance bounds for burst resolution time, i.e., the worst
case time it takes to connect a burst of M2M devices to the base station. We
illustrate the accuracy of the proposed methodology and its potential
applications in performance assessment and system dimensioning.Comment: Presented at IEEE International Conference on Communications (ICC),
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