检索结果-南通市图书馆

在线全文

学校读者我要写书评

暂无评论

空气流量对空冷燃料电池电堆性能的影响研究

化工学报 2022年第7期73卷 3222-3231页

作者：魏琳郭剑廖梓豪 ahmed mohmed dafalla 蒋方明中国科学院广州能源研究所先进能源系统研究室广东广州510640 中国科学院可再生能源重点实验室广东广州510640 中国科学院大学北京100049

空冷型氢燃料电池采用开放型阴极,具有自增湿、系统简单轻便等特点。为了揭示空气流量对输出性能的影响机制,对自组装的800 W空冷型燃料电池电堆进行了实验测试和数值分析,对比了不同空气风扇转速下电堆输出电压、净功率以及传质传热特... 详细信息

空冷型氢燃料电池采用开放型阴极,具有自增湿、系统简单轻便等特点。为了揭示空气流量对输出性能的影响机制,对自组装的800 W空冷型燃料电池电堆进行了实验测试和数值分析,对比了不同空气风扇转速下电堆输出电压、净功率以及传质传热特性。结果表明:小电流条件下小空气流量可以保持电堆内较高的温度,减少活化损失,实现高净输出功率。然而,大电流条件下,小空气流量将导致电堆温度过高且分布不均匀。利用数值方法对组分和温度分布进行了可视化分析,结果表明低含水量引起的欧姆损失增加是限制输出功率的关键因素,通过提高风扇转速增加空气流量可以保证较好的冷却效果,从而提高含水量,减少欧姆损失。

关键词：燃料电池传热传质水热管理数值分析

维普期刊数据库博看期刊

在线全文

学校读者我要写书评

暂无评论

交错布置蜿蜒流道的PEMFC冷启动特性

工程热物理学报 2023年第10期44卷 2798-2807页

作者：廖梓豪魏琳 ahmed mohmed dafalla 郭剑黄旭锐蒋方明广东电网有限责任公司广州供电局广州510600 中国科学院广州能源研究所广州510640 中国科学院可再生能源重点实验室广州510640 广东省新能源和可再生能源研究开发与应用重点实验室广州510640 中国科学院大学北京100049

质子交换膜燃料电池(PEMFC)在零下温度下的冷启动是影响其市场化的重要障碍。流场构型在一定程度上决定了反应物/生成物的输运,影响着PEMFC的冷启动性能。本研究利用PEMFC冷启动模型,分析了交错布置蜿蜒流道流场(ZFFCA)、蜿蜒流道平行流... 详细信息

质子交换膜燃料电池(PEMFC)在零下温度下的冷启动是影响其市场化的重要障碍。流场构型在一定程度上决定了反应物/生成物的输运,影响着PEMFC的冷启动性能。本研究利用PEMFC冷启动模型,分析了交错布置蜿蜒流道流场(ZFFCA)、蜿蜒流道平行流场(ZPFF)和直通道平行流场(SPFF)的冷启动特性。研究发现,ZFFCA能更好地分布PEMFC内的反应物/生成物、电流密度、热和冰,交错布置的形式更进一步强化了PEMFC的传热传质,有利于冷启动成功;但使用ZFFCA在冷启动过程中PEMFC温度爬升速率较低,不利于快速冷启动。

关键词： PEM燃料电池零下温度冷启动数值仿真流场构型

在线全文

学校读者我要写书评

暂无评论

夹紧压力对PEMFC冷启动性能的影响

工程热物理学报 2022年第4期43卷 1004-1012页

作者： ahmed mohmed dafalla 魏琳廖梓豪 BEREKET Tsegai Habte 蒋方明中国科学院可再生能源重点实验室中国科学院广州能源研究所先进能源系统研究室广州510640 中国科学院大学北京100049

质子交换膜燃料电池(PEMFC)作为一种电化学装置,以其高效、低排放、结构紧凑、静音等优点,被认为是未来最具有潜力的发电系统,然而其在低温环境下的快速启动是车用燃料电池面临的重要挑战之一。本文采用有限元法和非等温冷启动数值模型... 详细信息

质子交换膜燃料电池(PEMFC)作为一种电化学装置,以其高效、低排放、结构紧凑、静音等优点,被认为是未来最具有潜力的发电系统,然而其在低温环境下的快速启动是车用燃料电池面临的重要挑战之一。本文采用有限元法和非等温冷启动数值模型对夹紧压力作用下PEMFC的变形及非等温冷启动过程进行了求解,分析了扩散层厚度及非均匀变形对传质传热、电流密度和冰分布以及输出电压特性的影响。结果表明,扩散层非均匀变形会增加脊下区域传质阻力,加剧氧气的不均匀分布,而位于通道下区域的阴极催化层内的反应更加剧烈,使得PEMFC升温更快,且当夹紧压力为1~2 MPa时冷启动性能最佳。

关键词：质子交换膜燃料电池夹紧压力冷启动气体扩散层数值模拟

A Novel Layered Double Hydroxide and Dodecyl Alcohol Assisted PCM Composite with High Latent Heat Storage Capacity and Thermal Conductivity

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2024年第2期33卷 537-547页

作者： AL-ahmed Amir SARI Ahmet KHAN Firoz AL-RASHEIDI Masoud Hekimoğlu Gökhan AFZAAL Mohammad A.ALSULAMI ahmed dafalla Hatim SALHI Billel A.ALSULAIMAN Fahad Interdisciplinary Research Center for Renewable Energy and Power Systems(IRC-REPS) King Fahd University of Petroleum&MineralsDhahran31261Saudi Arabia Department of Metallurgical and Material Engineering Karadeniz Technical UniversityTrabzon61080Turkey Maths and Natural Sciences Division Higher Colleges of TechnologyP.O.Box 7947SharjahUnited Arab Emirates Department of Mechanical Engineering King Fahd University of Petroleum&MineralsDhahran31261Saudi Arabia Core Research Facilities King Fahd University of Petroleum&MineralsDhahran31261Saudi Arabia Interdisciplinary Research Center for Membranes and Water Security King Fahd University of Petroleum&MineralsDhahran31261Saudi Arabia

Dodecyl alcohol(DDA) is a promising solid-liquid phase change material(PCM) due to its favorable latent heat storage(LHS) ***,the leakage issue of PCM in a melted state during the heating period and low thermal conductivity restricts its utilization potential in thermal energy storage(TES) *** the same context,the present work aims to overcome the leakage issue and improve the thermal conductivity of the *** this in mind,a novel leak-proof layered double hydroxide(LDH)/DDA composite PCM is proposed through a solution-based impregnation *** leak-proof impregnation ratio of the DDA impregnated within the cavities of the synthesized Al/Fe-LDH was determined to be 60%.Detailed morphological,physicochemical,and thermal properties of the fabricated composite were studied by scanning electron microscopy(SEM),Fourier transforms infrared(FTIR) spectroscopy,X-ray diffraction(XRD)spectroscopy,differential scanning calorimetry(DSC),thermalgravimetric analysis(TGA),and thermal cycling *** results show that the LDH/DDA composite has a suitable phase change temperature(about 20℃) for passive solar thermal management of building *** composite PCM showed high LHS enthalpy(about136 J/g),good thermal stability,and cycling LHS *** also showed nearly 152% higher thermal conductivity compared to that of pure DDA,ultimately reducing the melting and solidification time of the pure DDA by 44.9% and 45.5%,respectively.

关键词： dodecyl alcohol layered double hydroxide composite PCM thermal conductivity thermal energy storage(TES)

Alternate Two Different Modes of Actions of Green Chemicals to Combat Batrachedra amydraula Meyrick and Cadra cautella Walk on Date Palm Fruit, Egypt

在线全文

学校读者我要写书评

暂无评论

Journal of Agricultural Science and Technology(A) 2014年第6期4卷 529-534页

作者： ahmed Amin Sayed Sobhy ahmed Temerak Salah Mahmood mohmed Gameel Amr Moussa Plant Protection Research Institute Agricultural Research Center Ministry of Agricu#ure (MOA) Cairo 11728 Egypt Plant Protection Department Faculty of Agriculture Assiut University Assiut 71515 .Egypt Plant Protection Research Institute Agricultural Research Center MOA Cairo 11728 Egypt Research & Development Department Dow Agro Sciences Company Indianapolis 46268 USA

Alternate two different modes of actions of green chemicals： spinosad ＆ methoxyfenozide to combat the lesser date moth, Batrachedra amydraula and the Almond moth, Cadra cautella Walk on dates in Dakhla Oasis, New Valley, Egypt were done in 2010 and 201 I. Based on infestation of the early insect pest B. amydraula, the three-rotation program with basic 1st spray of spinosad 24 SC at 20 mL/100 L showed insignificant difference. Based on minimum effective rotation doses, alternating spinosad 24 SC at 20 mL/100 L, then methoxyfenozide 24 SC at 15 mL/100 L with two-week interval showed zero infestation and 1.8% at the last sample of 2010 and 2011, respectively. Based on infestation of the late insect pest, Cadra spp., tlhe same previous trend of the three-rotation results. Based on minimum effective rotation doses, alternating spinosad 24 SC at 20 mL/100 L, then methoxyfenozid 24 SC at 15 mL/100 L with three-week interval indicated less than 1% and 1% infestation during harvest for 2010 and 201 l, respectively. The last reflected important value when storing the fruit. Both products proved to be working under dry hot high temperatures.

关键词： Alternation green chemicals B. amydraula Cadra cautella date fruit.

The Expression of miRNAs in Sudanese Patients with Systemic Lupus Erythematosus in Khartoum State

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Rheumatology and Autoimmune Diseases 2022年第4期12卷 128-136页

作者： Sarah Mohammed dafalla ahmed Elhadi Elsadig Tarig A. M. Hamid Huda Mohamed Haroun Sana Eltahir Abdalla Department of Haematology Medical Laboratory Sciences Program Alyarmouk College Khartoum Sudan Department of Haematology Faculty of Medical Laboratory Sciences Alzaiem Al Azhari University Khartoum Sudan Department of Haematology and Immunohematology Sharq El Nile College Khartoum North Sudan Department of Haematology Faculty of Medical Laboratory Sciences University of Gezira Madani Sudan Department of Pathology Faculty of Medicine Al Neelain University Khartoum Sudan

Background: MicroRNAs (miRs) are noncoding gene regulators that may have a role as diagnostic or prognostic biomarkers in systemic lupus erythematosus (SLE). Aim: To measure the blood levels of miR-146a, miR-126 and miR-30a in Sudanese SLE patients and to investigate their potential role in disease pathogenesis and utility as biomarkers for SLE. Material and Methods: A total of 48 SLE patients and 20 matched healthy individuals were enrolled in this study. SLE disease activity index (SLEDAI) was assessed. The blood levels of miR-146a, miR-126 and miR-30a were determined by Real-time polymerase chain reaction (PCR) in all participants. Γ-INF and IL-2 were analyzed by ELISA, and CD markers were used in flow cytometry. Results: The mean age of the patients was 31.5 ± 8.5 years with disease duration > 5 years. In SLE patients, the mean blood level fold changes of miR-146a (0.33 ± 0.277;P 0.305) compared to controls. Down regulation of miR-146a increase expression of γ-INF (P 0.05) as no differences between the SLE patients and healthy control. Conclusion: Circulating miR-146a and miR-126 could be a potential noninvasive biomarker in SLE. This study provides an overview of the current state of research on the role of miRNAs in the immune pathogenesis and regulation of SLE. Further studies are needed in miRNAs profiling expressions of SLE diseases.

关键词： Systemic Lupus Erythematosus (SLE) MicroRNAs

汉语复合趋向补语“上去、上来、下去、下来”偏误研究 ——以苏丹喀土穆大学学生为例

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

汉语复合趋向补语“上去、上来、下去、下来”偏误研究 ...

作者：柳飞絮（ESRA SALIH mohmed ahmed）西北师范大学

学位级别：硕士

近年来,许多学者在趋向补语这个语法点上进行了大量的研究,就目前情况来看,针对汉语教学的大部分趋向补语研究是关于亚洲和欧洲国家的汉语学习者,而针对非洲和阿拉伯国家的汉语学习者的研究却是很少。最近几年学习汉语的阿拉伯语学生数... 详细信息

近年来,许多学者在趋向补语这个语法点上进行了大量的研究,就目前情况来看,针对汉语教学的大部分趋向补语研究是关于亚洲和欧洲国家的汉语学习者,而针对非洲和阿拉伯国家的汉语学习者的研究却是很少。最近几年学习汉语的阿拉伯语学生数量不断的增多,趋向补语教学是对外汉语教学的个难点,特别是对于母语中没有趋向补语这类语法现象的阿拉伯学生,对他们来说趋向补语是最难掌握的语法部分之一。因此,本文对苏丹学生对趋向补语的使用情况进行了研究,为了对复合趋向补语进行相关的分析和研究,笔者通过调查问卷的分析和总结,对苏丹学生在运用复合趋向补语时出现的问题进行深入的探讨,以帮助苏丹和阿拉伯学生更容易理解和运用复合趋向补语,并对复合趋向补语的教学和学习提供可行的建议。本文共分为四章,第一章作为本篇论文的绪论,主要阐述了选题缘起、从本体研究和汉语教学研究这两个方面对本论文研究的问题而做了综述、研究内容与对象和本文的研究方法。第二章主要是从语义和语用方面辨析了“上去、上来、下去、下来”这四个趋向动词。第三章主要对苏丹学生使用复合趋向动词“上去、上来、下去、下来”的情况进行调查与分析,包括对问卷所体现结果的分析以及对问卷中复合趋向补语“上去、上来、下去、下来”偏误原因的分析,通过问卷的统计与分析而指出了笔者发现的偏误类型和原因。第四章承接第三章的分析与笔者发现的偏误而给予一些教学和学习方面的建议。最后本论文的结语,主要对本研究的一些经验和不足给予了说明,旨在为以后的研究指出方向。

关键词：趋向补语 “上去、上来、下去、下来” 苏丹学生偏误分析

Diagnostic Performance of glmM Gene and Histological Stains for Detection of Helicobacter pylori in Gastric Biopsy from Patients Admitted to Wad Madani Teaching Hospital, Sudan

同方学位论文库评论

在线全文

同方学位论文库

学校读者我要写书评

暂无评论

Natural Science 2022年第8期14卷 343-352页

作者： Karima Ali Hamid Albadawi Abdelbagi Talha Abdalraheem Ali Babiker Mohammed Ibrahim Malik Adam Dawoud Abakar Omer Mustafa Elsidig A Saeed mohmed Bushra ahmed Elhadi Abdalla ahmed Department of Histopathology and Cytology Faculty of Medical Laboratory Sciences University of Gezira Wad Medani Sudan Department of Clinical Laboratory Sciences College of Applied Medical Sciences Jouf University Al Jouf Kingdom of Saudi Arabia Department of Medicine Faculty of Medicine University of Gezira Wad Medani Sudan Department of Medical Microbiology Faculty of Medical Laboratory Sciences University of Gezira Wad Medani Sudan

Helicobacter pylori is the microbial agent most responsible for gastro-duodenal ulcer and chronic gastritis, which can develop into carcinoma of the stomach. This study was performed in Wad Medani Teaching Hospital, Sudan to detect Helicobacter pylori in stomach samples, and evaluate the performance of the tests used, which were histological stains and PCR. Gastric biopsies were obtained from 105 referred patients during endoscopy, and fixed specimens examined by haematoxylin-eosin and Warthin-Starry silver stains, while DNA was extracted for glmM gene amplification. Epigastric pain was the most common symptom at 78% (82/105) and chronic gastritis recorded with 71% (68/105) of endoscopy results. Warthin-Starry silver stain gave 31% (33/105) as positive for Helicobacter pylori followed by glmM gene 27% (28/105) and haematoxylin-eosin 24% (25/105). The study indicated good performance of histological staining and high specificity of glmM gene in detection of Helicobacter pylori from gastric biopsies.

关键词： Helicobacter pylori Histological Stains glmM Gene Gastric Biopsy Sudan

Case Report: Post Lumbar Discectomy Acute Iliac Arteriovenous Fistula;Endovascular Management and Literature Review

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Neuroscience & Medicine 2020年第4期11卷 142-151页

作者： Mohamed A. Khoudir Ghassan M. Aweja Abdulkarim M. Katebi ahmed Farag Mahmoud S. Attia mohmed S. Sobih Department of Neurosurgery Portsaid University Hospital Port Said Egypt Department of Neurosurgery Aseer Central Hospital Abha KSA Department of Neurosurgery King Abdullah Medical City Makkah KSA Department of Vascular Surgery National Institute of Diabetes and Endocrinology Cairo Egypt Department of Neurosurgery Khamis Mushait General Hospital Khamis Mushait KSA

Posterior approach lumbar disc surgeries (LDS) can be associated with serious iatrogenic vascular complications which could be a serious life threatening condition. We report a rare case of right sided acute iliac vessels iatrogenic arteriovenous fistula (IAVF) which was diagnosed and managed in 24 hours duration in a 45 years old healthy female who underwent surgical posterior approach L4-5 discectomy. Intraoperative, she developed sudden hypotension, tachycardia, wide pulse pressure and acute drop of hemoglobin level without obvious operative site bleeding which raise the index of suspicion of vascular injury and urge the team for doing emergency CT angiography (CTA), vascular and endovascular team consultation for digital subtraction angiography (DSA) and endovascular management. Endovascular stenting is nowadays the modality of choice of intervention. We provide case report with literature review.

关键词： Iliac Arteriovenous Fistula Post-Discectomy AVF Endovascular