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Experimental and numerical investigation of the abrasive waterjet machining of aluminum-7075-T6 for aerospace applications

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Advances in Manufacturing 2021年第2期9卷 286-303页

作者： Joseck Nyaboro mahmoud ahmed Hassan El-Hofy Mohamed El-Hofy Department of Industrial and Manufacturing Engineering Egypt-Japan University of Science and Technology(E-JUST)Alexandria 21934Egypt Department of Energy Resources Engineering Egypt-Japan University of Science and Technology(E-JUST)Alexandria 21934Egypt Advanced Manufacturing Research Centre(AMRC)with Boeing The University of SheffieldRotherham S605TZUK

The machining of hard-to-cut materials with a high degree of precision and high surface quality is one of the most critical considerations when fabricating various state-of-the-art engineered *** this investigation,a comprehensive three-dimensional model was developed and numerically simulated to predict kerf profiles and material removal rates while drilling the aluminum-7075-T6 aerospace *** profile and material removal prediction involved three stages:jet dynamic flow modeling,abrasive particle tracking,and erosion rate *** investigations were conducted to validate the developed *** results indicate that the jet dynamic characteristics and flow of abrasive particles alter the kerf profiles,where the top kerf diameter increases with increasing jet pressure and standoff *** kerf depth and hole aspect ratio increase with jet pressure,but decrease with standoff distance and machining *** profiles were characterized by progressive edge rounding and parabolic *** can be minimized by utilizing high jet pressure and small standoff *** material removal rate increases with increasing jet pressure,abrasive particle size,and exposure time,but decreases with increasing standoff distance.

关键词： Non-traditional machining Abrasive waterjet machining Computational fluid dynamics(CFD) Erosion modeling Kerf characteristics

Acute kidney injury due to bilateral malignant ureteral obstruction:Is there an optimal mode of drainage?

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World Journal of Nephrology 2022年第6期11卷 146-163页

作者： Rabea ahmed Gadelkareem ahmed mahmoud Abdelraouf ahmed Mohammed El-Taher Abdelfattah Ibrahim ahmed Department of Urology Assiut Urology and Nephrology HospitalFaculty of MedicineAssiut UniversityAssiut 71515AssiutEgypt

There is a well-known relationship between malignancy and impairment of kidney functions,either in the form of acute kidney injury or chronic kidney *** the former,however,bilateral malignant ureteral obstruction is a surgically correctable factor of this complex *** warrants urgent drainage of the kidneys in emergency ***,there are multiple controversies and debates about the optimal mode of drainage of the bilaterally obstructed kidneys in these *** review addressed most of the concerns and provided a comprehensive presentation of this topic from the recent ***,we provided different perspectives on the management of the bilateral obstructed kidneys due to *** the frequent trials for improving the success rates and functions of ureteral stents,placement of a percutaneous nephrostomy tube remains the most recommended tool of drainage due to bilateral ureteral obstruction,especially in patients with advanced ***,the disturbance of the quality of life of those patients remains a major unresolved *** the unfavorable prognostic potential of the underlying malignancy and the various risk stratification models that have been proposed,the response of the kidney to initial drainage can be anticipated and evaluated by multiple renal prognostic factors,including increased urine output,serum creatinine trajectory,and time-to-nadir serum creatinine after drainage.

关键词： Acute kidney injury Kidney Malignancy Percutaneous nephrostomy Ureteral obstruction Ureter

Multi-Objective Node Placement Problem in Wireless Network

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Multi-Objective Node Placement Problem in Wireless Network

作者： mahmoud Gamal ahmed Bekhit 湖南大学

学位级别：硕士

无线网络规划包括很多应该考虑的重要问题。尤其是许多研究者试图提出各种方案来提高网络的性能和效率:通过寻找最佳规划的蜂窝网络,选择节点在无线局域网(Wlans)的位置和访问类型,以及将基站和节点放置在中的多目标网络中。对于提高网... 详细信息

无线网络规划包括很多应该考虑的重要问题。尤其是许多研究者试图提出各种方案来提高网络的性能和效率:通过寻找最佳规划的蜂窝网络,选择节点在无线局域网(Wlans)的位置和访问类型,以及将基站和节点放置在中的多目标网络中。对于提高网络的效率及性能鲁棒性、自我管理、灵活性和任务支持,无线网络基础设施的管理起着非常重要和关键的作用。基础设施位置的设定可分为基站布置问题和天线的布置问题。前者与基站的位置有关,而后者与对某些特定候选基站的节点天线分配有关。本论文所述无线节点布置问题是一个天线问题。基站布置问题和天线的布置问题,就目前所知,都是NP难的。即在P≠NP的假设下,没有确定的算法可以在多项式时间内解决这一问题。值得一提的是,布置一个新的天线非常昂贵,不仅仅是因为设备上的花费,还有正确的设备安装方法和系统规划的花费,这使得通过常规的方法(如单元分裂)增加系统容量不具有吸引力。此外,由于有限的无线带宽,网络无法同时支持大量用户,尤其是对于需要大量、快速的数据传输速率的应用程序。无线网络集成也许可以以较高数据传输率提供服务,同时节约成本。然而,无线局域网的信号覆盖范围很小(特别是在城市地区),只能向在其覆盖面积内的用户,通过固定的接入点方式提供服务。为了克服这一缺点,使其能够为大多数用户服务,必须要部署高密度的无线局域网接入点。但是,此解决方案会导致成本增加,并降低固定基础设施的效率。无线节点布置问题就是构建一个优化的基础设施,即确定发射站的最佳位置——要考虑到覆盖面、成本、容量、干扰和切换这些特定因素。这些元素在问题模型中通常被定为目标、约束或两者都是,并会受到无线网络类型的影响,例如,数据通信或电信。已知这个问题是NP难的。在下文中,我们将详细描述节点布置问题,在本论文中使用的模型是基于这样一个模型——它与我们解决该问题的目标相适应,问题的说明与有关常数如下:●候选站E:考虑给定一组有限的候选站{e1,e2,……,,eE},D可用通信设备的总数。这些候选站eu的位置为(αu,βu)(?)u●通信设备D:考虑给定一组有限的通信设备{d1,d2,……,D},D是可用设备的总数。每个设备dv有功率pv,容量sv,消耗Cv,类型tv和功率范围wv,●接收器R:考虑有一组有限的接收器{r1,r2……,rR}被置于位置(αg,βg),R为接收器总数●通信设备dv可能被给定与其相关的接收器rg不同的信号阈值θgd和信号强度Sgv,i,u。信号阈值和信号强度一起,决定了节点覆盖范围。σgd是接收器rg从设备dv.索要数据的数据率●节点N:节点集{n1,n2,.....,N为需要布置的节点总数一个网络由从候选站点列表中的选定的站点和设备(从通信设备中选择不同的给定的数目和位置)组成。任务是在服务范围内布置一组节点ni,即使在有小干扰发生的情况下,所有与这些节点相关联的接收器rg都能被覆盖。在本论文中,我们要处理异构网络的节点布置问题,我们必须优化节点位置,使其通信能够覆盖新建立的网络,此外我们解决了新的节点部署问题和将它们组合到原有基础设施的问题。每个节点的nj有一组特定的标识,比如:成本为c,功率和容量等等。我们在本文中有两个假设:首先,如果有一个新的基础设施,并想要在其中配置一组节点必须要考虑我们的目标和约束条件;其次,我们假设我们通过现有网络的时间范围知道了需求分布,同时我们想要部署新节点,并通过现有的基础设施将其组合进去。现有的基础设施架构是一个同质或异质的节点集合,这些节点与稳定的分层网络关联,并连接每个通信设备类型。这些构成了现有网络的节点有一系列特征如:功率、计算能力和覆盖范围的大小。此外,我们必须有一个现有网络基础设施的主要集,定义为Hd,其中基础设施与每个通信设备dv相关联。只有在有需要时,我们才添加这些额外节点。此外,这些额外的节点应满足系统的限制,还应该能够通过网络进行协作、通信和协商。我们提供了我们知道的通信设备dv和节点集N。我们的主要目标是在特定区域的覆盖范围中找到最佳位置、数目、通信类型和连接。进一步的,我们还解释了节点和通信设备D,候选站点M及其它节点ni之间的通信过程。与通信设备相关联的节点我们认为,为每个节点ni可分配给一组通信设备D。也就是说,对于每个节点的nj可以通过一些通信设备dv连接到不同的通信网络。通信设备dv特征由不同的参数设定。我们的模型提出考虑了功率、容量、成本、通信设备类型、功率范围和带宽,每个通信设备dv可以描述为六元组τ=(p、s、c、t、w、b),其中p表示要将节点连接到接收器的功率,s表示节点提供的控制测试点的数据需求的带宽或者能力,c表示通讯设备成本,t表示通信设备类型,在这里,我们只使用一种类型,w表示要连接网络中的节点所需的功率范围,b表示两个连接网络的节点之间的带宽。与候选站点相关联

关键词：无线网络节点布置遗传算法优化问题基于分解的多目标进化算法

Wear Characteristics of Functionally Graded Tubes Reinforced with Silicon Carbide and Alumina: A Comparative Study

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Transactions of Nanjing University of Aeronautics and Astronautics 2021年第S1期38卷 76-83页

作者： SALEH Bassiouny Ibrahim ahmed mahmoud Hamed Production Engineering Department Alexandria UniversityAlexandria 21544Egypt College of Mechanics and Materials Hohai UniversityNanjing 211100P.R.China

In the current study,an effort has been taken to manufacture and compare the characteristics of functionally graded tubes. Two samples have been produced with a commercially pure aluminium matrix reinforced by 10%(in weight) SiC and Al_(2)O_(3)with a 16 μm average size via horizontal centrifugal casting. In addition to microstructure analysis,the mechanical and wear characteristics have been investigated across the thickness of the produced *** results showed that the addition of SiC and Al_(2)O_(3)particles relative to the unreinforced matrix(pure Al)significantly enhance the mechanical properties and wear resistance of the produced tubes. Thus,these tubes are the best choice for automobile applications.

关键词： functionally graded materials centrifugal casting pure aluminium wear characteristics

Virtual orthopedic assessment:Main principles and specific regions

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World Journal of Orthopedics 2021年第9期12卷 672-684页

作者： Khaled M Emara Ramy ahmed Diab Mohamed Amr Shady Abdelghaffar mahmoud Mohamed Nour ahmed Abdelsalam mahmoud ahmed Elshobaky Mona Farhan Mostafa Gemeah ahmed K Emara Orthopedic Surgery Department Ain Shams UniversityCairo 11566Egypt Orthopedic Surgery Department Bank Ahly HospitalCairo 11566Egypt Department of Health Care Innovation Arizona State UniversityArizonaAZ 85287United States Department of Orthopedic Surgery Cleveland ClinicOhioNY 44195United States

Telemedicine was originally created as a way to treat patients who were located in remote places far away from local health facilities or in areas with shortages of medical *** is still used today to address those problems,and is increasingly becoming a tool for convenient medical *** the emergence of pandemics,telemedicine became almost a mandatory and valuable option for continuing to provide medical care in various *** the threat of pandemic progress has continued for months and may continue for years,it is essential to validate existing tools to maintain clinical assessment and patient treatment to avoid negative consequences of the lack of medical ***,the establishment of a virtual assessment technique that can be conducted effectively is of outmost importance as a way of adapting to the current *** study evaluated the role of telemedicine in the assessment of various orthopedic pathologies by means of a systematic virtual evaluation.

关键词： Telemedicine Virtual assessment Orthopedics Epidemic diseases

Synthesis of Ag3PO4-based Composites for Photocatalytic Degradation of Organic Dyes

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Synthesis of Ag3PO4-based Composites for Photocatalytic Degr...

作者： ahmed mahmoud Idris Mohamed(阿麦) 西北师范大学

学位级别：硕士

近年,半导体催化剂在可见光照射下光催化降解有机污染物引起了很大关注,因为这是一个有前景,环境友好,成本低廉,高效的工艺。为了更好的使用占大约43%太阳能的可见光,迫切需要可见光催化剂氧化降解有机污染物。这种具有高的氧化能力的... 详细信息

近年,半导体催化剂在可见光照射下光催化降解有机污染物引起了很大关注,因为这是一个有前景,环境友好,成本低廉,高效的工艺。为了更好的使用占大约43%太阳能的可见光,迫切需要可见光催化剂氧化降解有机污染物。这种具有高的氧化能力的技术已被广泛用于消除持久性污染有机物和微生物废水中。(Ag3P0)磷酸银的带隙为2.43eV,作为一种新型催化剂,它表现出非常高的对水的光氧化能力和在可见光照射下对有机染料的光降解能力。通过使用磷酸银氧化水生氧的量子产率在光照为420nm时波长差不多达到90%。因此,磷酸银在光催化性能上很有发展前景。生成电子的氧化还原反应的潜力,光诱导快速重组产生电子空穴和磷酸银的表面形貌被认为是影响光催化性能的主要因素。在本论文中,主要研究目标是了解磷酸银的表面形貌和结构性质,光催化电子的效果和开发高纯的能产生和分离电子空穴的磷酸银,以及基于磷酸银的光催化剂对环境的净化作用。为了达到这一目标,我们成功的合成并研究了基于磷酸银的两种新型的光催化复合材料。本论文主要分为三部分：第一章,我们对半导体光催化剂和光催化剂如何净化环境进行了概述。其次,我们讨论了合成和利用高效的磷酸银的细节以提供开发高效磷酸银复合材料净化环境的有用信息。除此之外,我们也讨论了合成不同结构的磷酸银的方法以及获得高效的具有光催化活性的材料的策略。第二章,为了提高磷酸银在可见光照射下的光催化反应性能,通过功能化还原氧化石墨烯和Fe3O4磁性纳米粒子复合物,我们制造了一种新型的光催化剂。RGO-Fe304-Ag3P04的合成制备是通过简单有效的静电自组装方法。产物的形貌和结构的表征是通过透射电子显微镜,扫描电子显微镜,X-射线衍射,紫外线-可见漫反射光谱,红外光谱,以及光致发光完成的。通过X-射线光谱分析我们证实了合成的纳米粒子的存在元素。RGO-Fe304-Ag3P04复合材料的光催化活性是通过在可见光下以及较短的光照时间内几乎完全降解罗丹明B来评估的。该材料具有优良的可循环性,在光催化过程中有高效的电子-空穴分离。第三章,制备了一种新型的Fe3O-Ag3PO4@AgI光催化剂,该催化剂能在可见光照射下诱导光降解甲基橙。该纳米粒子通过简单有效的原位离子交换方法合成,并通过扫描电子显微镜,X-射线衍射,紫外线-可见漫反射光谱表征。结果证实,磁性纳米粒子和碘化银分子在没有失去其磁性和光学功能的情况下都被固定在磷酸银的表面。Fe304-Ag3P04@AgI光催化剂显示比Ag3PO4@AgI和Ag3PO4更高的活性。Ag3PO4的光催化活性是通过在可见光下以及较短的光照时间内几乎完全降解甲基橙来评估的。该材料具有优良的可循环使用性。

关键词： RGO Fe3O4 Ag3PO4 光催化

Cartilage tympanoplasty in the treatment of adhesive otitis media with and without Eustachian tube balloon dilatation

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Journal of Otology 2022年第4期17卷 226-231页

作者： ahmed abdel rahman abdel aziz ahmed mahmoud Youssef Mostafa Mohamed Mostafa Mostafa talaat Khaled Mohamed Abdelzaher ahmed Adel Sadeq Department of Otorhinolaryngology Faculty of MedicineEl MiniaEgypt Radiology Department Faculty of MedicineEl MiniaEgypt

Purpose:To compare cartilage tympanoplasty(CT)combined with eustachian tube balloon dilatation(ETBD)and cartilage tympanoplasty alone as a surgical treatment modality for adhesive otitis media(AdOM)in terms of graft healing,audiological outcomes,and impact on life style,using Chronic Otitis Media Outcome Test 15(COMOT-15).Methods:50 patients with AdOM were randomly classified into 2 groups:25 patients for cartilage tympanoplasty only(CT group)and 25 patients for cartilage tympanoplasty combined with eustachian tube balloon dilatation(CT t ETBD group).Clinical outcomes in both groups were compared at 3 and 6 months of follow ***:There was no significant difference in graft healing between the two *** COMOT-15 scores significantly decreased in both groups with a significant difference between the groups with regard to the decrease in COMOT-15 scores at 3 and 6 months of follow-up(P<0.05).Hearing improvement was achieved,as the mean preoperative ABG was 26.5±5.4 and 27.1±4.6 dB,and the mean postoperative ABG at 6 months was 19.4±4.4 and 14.6±3.9 dB in the CT and the CT t ETBD groups,*** difference in the magnitude of ABG reduction in the two groups was significant at 3 and 6 months of postoperative follow-up(P<0.05)in favour of the CT t ETBD ***:ETBD can increase the success rate of cartilage tympanoplasty in patients with AdOM by enhancing the audiological outcome and quality of life.

关键词： balloon healing otitis

Molecular mechanisms of the anti-obesity potential effect of Moringa oleifera in the experimental model

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Asian Pacific Journal of Tropical Biomedicine 2017年第3期7卷 214-221页

作者： Fateheya Mohamed Metwally Hend Mohamed Rashad Hanaa Hamdy ahmed Asmaa ahmed mahmoud Ehab Ragaa Abdol Raouf Aboelfetoh Mohamed Abdalla Environmental and Occupational Medicine National Research CentreGizaEgypt Department of Hormones National Research CentreGizaEgypt Department of Zoology Faculty of ScienceAin Shams UniversityCairoEgypt Department of Research on Children with Special Needs National Research CentreGizaEgypt Department of Horticulture Crops Technology National Research CentreGizaEgypt

Objective: To elucidate the molecular mechanisms of the potent anti-obesity effect of Moringa oleifera Lam.(M. oleifera) ethanolic extract and to clarify the link between these mechanisms and the associated metabolic and vascular risks in the experimental model of visceral ***: M. oleifera ethanolic extract was orally administered at 600 mg/kg body weight in obese female rats daily for 12 weeks. At the end of treatment, body weight was determined, and the atherogenic index, coronary artery index, glucose level, insulin resistance status, liver and kidney functions were assessed. Also, the m RNA of leptin, adiponectin and resistin in visceral adipose tissue was determined by quantitative real ***: The results showed that M. oleifera extract down-regulated m RNA expression of leptin and resistin, while it up-regulated adiponectin gene expression in obese rats relative to untreated obese control counterparts. This amelioration of genes expression was paralleled by a reduction in body weight and improvement of the atherogenic index and coronary artery index, as well as glucose level and insulin resistance value without adverse effects on liver or kidney functions, versus the untreated obese control ***: It is reasonable to assume that the anti-obesity, anti-atherogenic and antidiabetic properties of M. oleifera are mechanistically achieved via working directly on the adipokines of the visceral adipose tissue. Therefore, M. oleifera may be a good therapeutic candidate for the symptoms of metabolic syndrome.

关键词： Moringa oleifera Lam Visceral adipose tissue Adipokines Gene expression Rats

Trends on gastrointestinal bleeding and mortality:Where are we standing?

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World Journal of Gastroenterology 2012年第11期18卷 1154-1158页

作者： ahmed mahmoud El-Tawil Department of Surgery University Hospital Birmingham

Bleeding from the gastrointestinal tract and its management are associated with significant morbidity and *** predisposing factors that led to the occurrence of these hemorrhagic instances are largely linked to the life style of the affected *** a new strategy aimed at educating the publics and improving their awareness of the problem could effectively help in eradicating this problem with no associated risks and in bringing the mortality rates down to almost zero.

关键词： Gastrointestinal bleeding Peptic ulcer Esoph-ageal varices Helminthic infestation Bowel cancer Mor-tality Morbidity Predicting factors Age Sex