Despite their potential as a sustainable energy technology, the operation of proton exchange membrane fuel cells (PEMFCs) in sub-freezing conditions remains a critical challenge due to the risk of ice formation and performance degradation. This study introduces a new passive thermal management technique using strategically arranged multi-layer phase change materials (PCMs) to address this challenge. A numerical model was developed to evaluate the thermal behavior across various PCM configurations, incorporating one, two, and three layers arranged both in parallel and series with distinct melting points ranging from 55 to 65 ◦C. The results show that multi-layer PCM configurations provide significant improvements over the single-layer base

The demands of professional, scientific, and academic life have made it necessary to identify the various difficulties faced by postgraduate female students, which lead to problems that hinder their achievement of the required goals. This necessitates directing efforts toward finding solutions to confront and solve problems through appropriate cognitive behavior. Therefore, this study aimed to identify information processing styles and problem-solving and their relationship with metamotivation and perceived control among postgraduate female students (PhD/Master's). To achieve this aim, the descriptive approach using the survey method was adopted due to its suitability to the nature of the research problem. The population was defined

Structure type and disorder have become important questions in catalyst design, with the most active catalysts often noted to be “disordered” or “amorphous” in nature. To quantify the effects of disorder and structure type systematically, a test set of manganese(III,IV) oxides was developed and their reactivity as oxidants and catalysts tested against three substrates: methylene blue, hydrogen peroxide, and water. We find that disorder destabilizes the materialsthermodynamically, making them stronger chemical oxidantsbut not necessarily better catalysts. For the disproportionation of H2O2 and the oxidative decomposition of methylene blue, MnOx-mediated direct oxidation competes with catalytically mediated oxidation, making the most

Objectives: The study aimed to clarify the role of Al-Sayyid Al-Ajall and his family in the service of the Mongol Empire. They worked to develop its administrative and military institutions, benefiting from their extensive experience in administration, politics, economics, and urban affairs. Due to their capabilities, they received the patronage of Genghis Khan and subsequent generations, earning the confidence of the ruling Mongol authority. As a result, they were granted significant powers within the state.       Methods: The study relied on the analytical method to analyze historical texts, compare them with others, and discuss them accurately. Results: The study yielded several results, including the minister's keen interes

Characterized the study of Islamic movements in Lebanon, as other studies in the Arab world by being the study of the subject in a different and distinct field on more than one level, environment in which they were composed of components very sectarian and confessional diversity

إن قراءة شبه متأنية لبعض مواقف الاِمام السجاد( عليه السلام ) من الظالمين وأعوانهم ، وكذلك مواقفه من بعض الحركات الشيعية التي تفجّرت في زمانه ، وكيف انتقل من مرحلة التقية المؤلمة إلى مرحلة المواجهة الساخنة ، لا سيّما بعد أن استنفذ دوره التبليغي الصامت ، وارتأى أنّه لابدّ أن ينتقل من المرحلة السلبية السرية الصامتة إلى مرحلة اعلان المعارضة ، خاصة وإنّه أدرك أن خصومه عن دوره في تأليب الاُمّة ضدهم وتحشيد غضبها وإ

الخطاب السياسي الاسلامي واشكالية المراوحة بين الشورى والديمقراطية