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Moderate Secondary Tricuspid Regurgitation: Does It Worth More Time to Conserve?

Open Journal of Thoracic Surgery 2021年第3期11卷 59-68页

作者： Montaser Elsawy Abd Elaziz ahmed Labib Dokhan Awny Gamal Shalaby hesham hassan ahmed Mohammed ahmed El-Hag-Aly Mohammed Fawzy Eltaweel Cardithoracic Surgery Department Faculty of Medicine Menoufia University Menoufia Egypt Faculty of Medicine Jazan University Jazan KSA Cardiology Department Faculty of Medicine Menoufia University Menoufia Egypt

Background: Concomitant repair of moderate secondary tricuspid regurgitation (STR) during mitral valve surgery is still subject of controverse. This research aims to study the early and mid-term postoperative influence of tricuspid repair on the clinical outcomes and right ventricular functions. Methods: This is a retrospective cohort study of 92 patients with moderate STR who underwent tricuspid valve repair

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Evaluation of suturless scleral fixation with posterior chamber foldable intraocular lens implantation

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International Journal of Ophthalmology(English edition) 2019年第8期12卷 1283-1289页

作者： ahmed MBedda hesham FElGoweini ahmed MAbdelhadi Amr MElhady Department of Ophthalmology Alexandria UniversityAlexandria11511Egypt Department of Ophthalmology the General OphthalmologyHospitalAlexandria21515Egypt

AIM: To assess the sutureless scleral fixation technique for posterior chamber foldable intraocular lens(PCIOL) implantation in aphakic eyes with insufficient or no capsular support. METHODS: A technique for sutureless intrascleral fixation of the haptics of a standard 3-piece PCIOL was used which ensures sutureless fixation by permanent incarceration of the haptics in a scleral tunnel parallel to the limbus. All patients were evaluated for preoperative status [visual acuity, refractive error, K readings, intraocular pressure(IOP) measurement, slit lamp examination, fundus examination and optical biometry], postoperative status and complications. Ultrasound biomicroscopy(UBM) was done for 10 cases to evaluate optic tilt. RESULTS: The study evaluated 42 eyes of 42 patients. The follow-up period was 6 mo. Improvement of best corrected visual acuity(BCVA) one line occurred in 10 cases(23.8%) and loss of one line in 3 cases(7.1%). Intraoperative complications included: haptic kink in 4 cases(9.5%), haptic breakage in 1 case(2.4%), haptic dislocation in 1 case(2.4%), haptic slippage in 3 cases(7.1%), IOL dislocation in 1 case(2.4%) and sclerotomy related bleeding in 1 case(2.4%). Postoperative complications included: transient mild vitreous hemorrhage in 3 cases(7.1%), choroidal detachment in 1 case(2.4%), cystoid macular edema(CME) in 1 case(2.4%), optic capture in 1 case(2.4%), subconjunctival haptic in 2 cases(4.8%), ocular hypotony in 4 cases(9.5%) and ocular hypertension in 1 case(2.4%). There were no cases of retinal detachment or endophthalmitis. UBM showed optic tilt in 3 cases(30%). CONCLUSION: Fixation of three-piece foldable IOL haptics in scleral tunnel parallel to the limbus-providedaxial stability and proper centration of the IOL with minimal or no tilt in most cases and a low complication rate during the follow up period which lasted 6 mo.

关键词： aphakia correction sutureless scleral fixation foldable three-piece intraocular lens

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NeTrainSim:a network-level simulator for modeling freight train longitudinal motion and energy consumption

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Railway Engineering Science 2024年第4期32卷 480-498页

作者： ahmed S.Aredah Karim Fadhloun hesham A.Rakha Center for Sustainable Mobility Virginia Tech Transportation Institute3500 Transportation Research PlazaBlacksburgVA 24061USA

Although train modeling research is vast, most available simulation tools are confined to city-or trip-scale analysis, primarily offering micro-level simulations of network segments. This paper addresses this void by developing the Ne Train Sim simulator for heavy long-haul freight trains on a network of multiple intersecting tracks. The main objective of this simulator is to enable a comprehensive analysis of energy consumption and the associated carbon footprint for the entire train system. Four case studies were conducted to demonstrate the simulator's performance. The first case study validates the model by comparing Ne Train Sim output to empirical trajectory data. The results demonstrate that the simulated trajectory is precise enough to estimate the train energy consumption and carbon dioxide emissions. The second application demonstrates the train-following model considering six trains following each other. The results showcase the model ability to maintain safefollowing distances between successive trains. The next study highlights the simulator's ability to resolve train conflicts for different scenarios. Finally, the suitability of the Ne Train Sim for modeling realistic railroad networks is verified through the modeling of the entire US network and comparing alternative powertrains on the fleet energy consumption.

关键词： Ne Train Sim Network train simulation Train longitudinal motion Energy consumption Carbon footprint

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Fabrication of PMMA nanocomposite biomaterials reinforced by cellulose nanocrystals extracted from rice husk for dental applications

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Friction 2024年第12期12卷 2808-2825页

作者： ahmed FOULY Walid M.DAOUSH hesham I.ELQADY Hany S.ABDO Mechanical Engineering Department College of EngineeringKing Saud UniversityRiyadh 11421Saudi Arabia The King Salman Center for Disability Research Riyadh 11421Saudi Arabia Department of Production Engineering and Mechanical Design Faculty of EngineeringMinia UniversityMinia 61519Egypt Department of Chemistry College of ScienceImam Mohammad Ibn Saud Islamic University(IMSIU)Riyadh 11623Saudi Arabia Faculty of Technology and Education Helwan UniversityCairo 11281Egypt Faculty of Engineering Aswan UniversityAswan 81528Egypt Center of Excellence for Research in Engineering Materials(CEREM) King Saud UniversityRiyadh 11421Saudi Arabia Mechanical Design and Materials Department Faculty of Energy EngineeringAswan UniversityAswan 81521Egypt

The primary objective of global studies is to develop the properties and durability of polymers for various *** it comes to dental disability,denture base materials must have sufficient mechanical and tribological performance in order to withstand the forces experienced in the *** work aims to investigate the effects of the addition of low content of cellulose nanocrystals(CNC)on the mechanical and tribological performance of the polymethyl methacrylate(PMMA)*** weight percent of CNC(0,0.2,0.4,0.6,and 0.8 wt%)were added to the PMMA matrix followed by ball milling to evenly distribute the nanoparticles reinforced phase in the matrix *** findings emphasize the significant impact of CNC integration on the performance of PMMA *** increasing the content of the CNC nanoparticles,the mechanical properties of PMMA were *** addition,the tribological outcomes demonstrated a significant reduction in the friction coefficient besides an enhancement in the wear resistance as the weight percentage of nanoparticles *** surface of the worn samples was investigated by utilizing SEM to identify the wear mechanisms corresponding to the different *** addition,a finite elment model(FEM)was developed to ascertain the thickness of the worn layer and the generated stressed on the surfaces of the nanocomposite throughout the friction process.

关键词： polymethyl methacrylate nanocomposite cellulose nanocrystals denture materials rice husk polymethyl methacrylate(PMMA) wear resistance

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Novel colored flames via chromaticity of essential colors

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Defence Technology（防务技术） 2019年第2期15卷 210-215页

作者： Ramy Sadek Mohamed Kassem Mohamed Abdo ahmed Fahd hesham Tantawy Amir Elsaidy Sherif Elbasuney School of Chemical Engineering Military Technical College

Colored flame compositions have distinctive variety of applications ranging from military signaling,rocket tracking, and illuminating devices. Certain elements and compounds when heated to high temperature are able to emit unique wavelengths in the visible region. This study, reports on the development of novel colored flames that cannot be generated by emitting atomic/molecular species. This was achieved by using chromaticity of basic colored flames. Mixing of high quality primary colored flames including Blue, Yellow, and Red in proper ratio was conducted; any interfering incandescent emission resulted from MgO was eliminated using Al metal fuel. The spectral characteristics in terms of luminous intensity, and color quality were evaluated using digital luxmeter and UV-Vis. spectrometer *** quality mixed colored flames include violet, sweet pink, and marigold were developed. This study shaded the light on the state of the art for the real development of novel colored flame compositions and chromaticity of basic colored flames.

关键词： Pyrotechnics Colored flame Atomic spectroscopy Molecular spectroscopy Luminous intensity Color quality Chromaticity

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Effective damping of local low frequency oscillations in power systems integrated with bulk PV generation

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Protection and Control of Modern Power Systems 2021年第1期6卷 512-524页

作者： ahmed hesham Abd El-Kareem Mohamed Abd Elhameed Mahmoud M.Elkholy Operation Engineer at New Capital Power Plant New Capital CityEgypt Electrical Power and Machines Department Faculty of EngineeringZagazig UniversityZagazigEgypt

High penetration of renewable sources into conventional power systems results in reduction of system inertia and noticeable low-frequency oscillations (LFOs) in the rotor speed of synchronous generators. In this paper, we propose effective damping of LFOs by incorporating a supplementary damping controller with a photovoltaic (PV) generating station, where the parameters of this controller are coordinated optimally with those of a power system stabilizer (PSS). The proposed method is applied to damp local electromechanical modes by studying a system comprising a synchronous generator and a PV station connected to an infinite bus. The PV station is modeled following the instructions of the Western Electricity Coordinating Council. The problem is modeled as an optimization problem, where the damping ratio of the electromechanical modes is designed as the objective function. Constraints including upper and lower limits of decision parameters and damping ratio of other modes are considered by imposing penalties on the objective function. Different optimization algorithms are used to pursue the optimal design, such as political, improved gray wolves and equilibrium optimizers. The results validate the effectiveness of the proposed controller with PSS in damping local modes of oscillations.

关键词： Low frequency oscillations Damping controller PV WECC

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Effectiveness and safety of subthreshold vibration over suprathreshold vibration in treatment of muscle fatigue in elderly people

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World Journal of Clinical Cases 2023年第15期11卷 3434-3443页

作者： Ayman A Mohamed Esra Khaled Asma hesham ahmed Khalf Physical Therapy Nahda UniversityBeni Suef 23435Egypt Physical Therapy Beni-Suef UniversityBeni Suef 32456Egypt

Muscle fatigue is common in many populations,particularly *** increases the incidence of muscle fatigue and delays its *** is a huge debate about the current treatments for muscle fatigue,particularly in ***,it has been discovered that mechanoreceptors have an important role as a sensory system in sensing muscle fatigue which could enhance the body's response to muscle *** function of mechanoreceptors could be enhanced by applying either suprathreshold or subthreshold *** suprathreshold vibration improves muscle fatigue,it can cause desensitization of cutaneous receptors,discomfort,and paresthesia,which are barriers to clinical *** vibration has been approved as a safe and effective method of training for mechanoreceptors;however,its use and effectiveness in muscle fatigue have never been tested or *** physiological effects of subthreshold vibration in the treatment of muscle fatigue include:(1)Enhancing the function of mechanoreceptors themselves;(2)Increasing the firing rate and function of alpha motor neurons;(3)Increasing blood flow to fatigued muscles;(4)Decreasing the rate of muscle cell death in elderlies(sarcopenia);and(5)Driving motor commands and allow better performance of muscles to decrease fatigue *** conclusion,the use of subthreshold vibration could be a safe and effective treatment for muscle fatigue in *** could enhance recovery from muscle ***,Subthreshold Vibration is safe and effective in treating muscle fatigue in comparison to suprathreshold vibration.

关键词： Subthreshold Vibration Muscle Fatigue Elderly people

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Enhancing the explosive characteristics of a Semtex explosive by involving admixtures of BCHMX and HMX

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Defence Technology（防务技术） 2020年第2期16卷 487-492页

作者： ahmed Elbeih ahmed K.Hussein Tamer Elshenawy Svatopluk Zeman Sara M.Hammad Ahmad Baraka Mohamed A.Elsayed Mohamed Gobara hesham Tantawy Military Technical College Kobry ElkobbahCairoEgypt Technical Research Center CairoEgypt Institute of Energetic Materials Faculty of Chemical TechnologyUniversity of PardubiceCzech Republic Faculty of Pharmacy University of CairoGizaEgypt

A well-known ternary plastic explosive,Czech Semtex 1H,contains a mixture of PETN and RDX softened by *** this work,BCHMX was used to replace PETN in Semtex 1H to form Sem-BC+*** addition,another mixture based on BCHMX and HMX as energetic fillers bonded by the polymeric matrix of Semtex 1H(Sem-BC+HMX)was *** particle size distribution of each individual explosive was determined to obtain the optimum mixing *** and impact sensitivities were *** velocity of detonation was reported practically and the detonation properties were calculated by EXPLO5 *** explosive strength of each sample was measured by the ballistic mortar *** conclusion confirms that the velocity of detonation of Sem-BC+HMX was the highest in comparison with the prepared ***-BC+RDX has the least impact and frictions ***-BC+RDX has higher detonation velocity,detonation properties and explosive strength than Semtex *** of BCHMX in Semtex 1H as a replacement for PETN is the candidate to produce a high performance advanced Czech plastic explosive.

关键词： Semtex Explosives Combustion Sensitivity Detonation Explosive strength

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Spatial distribution of air temperature and relative humidity in the greenhouse as affected by external shading in arid climates

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Journal of Integrative Agriculture 2019年第12期18卷 2869-2882页

作者： hesham Aahmed TONG Yu-xin YANG Qi-chang Abdulellah AAl-Faraj ahmed MAbdel-Ghany Institute of Environment and Sustainable Development in Agriculture Chinese Academy of Agricultural SciencesBeijing 100081P.R.China Key Laboratory of Energy Conservation and Waste Management of Agricultural Structures Beijing 100081P.R.China Department of Agricultural Engineering College of Food and Agriculture SciencesKing Saud UniversityRiyadh 11451Saudi Arabia Department of Agricultural Engineering Faculty of AgricultureSana'a UniversitySana'a 2124Yemen

The effect of external roof shading on the spatial distribution of air temperature and relative humidity in a greenhouse(Tin and RHin) was evaluated under the arid climatic conditions of Riyadh City, Saudi Arabia. Two identical, evaporatively-cooled, single-span greenhouses were used in the experiment. One greenhouse was externally shaded(Gs) using a movable black plastic net(30% transmissivity), and the other greenhouse was kept without shading(Gc). Strawberry plants were cultivated in both greenhouses. The results showed that the spatial distribution of the Tin and RHin was significantly affected by the outside solar radiation and evaporative cooling operation. The regression analysis showed that when the outside solar radiation intensity increased from 200 to 800 W m–2, the Tin increased by 4.5℃ in the Gc and 2℃in the Gs, while the RHin decreased by 15% in the Gc and 5% in the Gs, respectively. Compared with those in the Gc, more uniformity in the spatial distribution of the Tin and RHin was observed in the Gs. The difference between the maximum and minimum Tin of 6.4℃ and the RHin of 10% was lower in the Gs than those in the Gc during the early morning. Around 2℃ difference in the Tin was shown between the area closed to the exhausted fans and the area closed to the cooling pad with the external shading. In an evaporatively-cooled greenhouse in arid regions, the variation of the Tin and RHin in the vertical direction and along the sidewalls was much higher than that in the horizontal direction. The average variation of the Tin and RHin in the vertical direction was 5.2℃ and 10% in the Gc and 5.5℃ and 13% in the Gs, respectively. The external shading improved the spatial distribution of the Tin and RHin and improved the cooling efficiency of the evaporative cooling system by 12%, since the transmitted solar radiation and accumulated thermal energy in the greenhouse were significantly reduced.

关键词： greenhouse temperature humidity distribution uniformity evaporative cooling shading arid climate

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Cloud‐based video streaming services:Trends,challenges,and opportunities

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CAAI Transactions on Intelligence Technology 2024年第2期9卷 265-285页

作者： Tajinder Kumar Purushottam Sharma Jaswinder Tanwar Hisham Alsghier Shashi Bhushan hesham Alhumyani Vivek Sharma ahmed I.Alutaibi CSE Department JMIETIYamunanagarHaryanaIndia Department of Information Technology ASETAmity University Uttar PradeshNoidaIndia Tata Communications Limited New DelhiIndia Department of Information Technology College of Computer and Information SciencesMajmaah UniversityMajmaahSaudi Arabia Amity School of Engineering and Technology Amity UniversityPatnaBiharIndia Department of Computer Engineering College of Computers and Information TechnologyTaif UniversityTaifSaudi Arabia Department of Computer Engineering College of Computer and Information SciencesMajmaah UniversityMajmaahSaudi Arabia

Cloud computing has drastically changed the delivery and consumption of live streaming *** designs,challenges,and possible uses of cloud computing for live streaming are studied.A comprehensive overview of the technical and business issues surrounding cloudbased live streaming is provided,including the benefits of cloud computing,the various live streaming architectures,and the challenges that live streaming service providers face in delivering high‐quality,real‐time *** different techniques used to improve the performance of video streaming,such as adaptive bit‐rate streaming,multicast distribution,and edge computing are discussed and the necessity of low‐latency and high‐quality video transmission in cloud‐based live streaming is *** such as improving user experience and live streaming service performance using cutting‐edge technology,like artificial intelligence and machine learning are *** addition,the legal and regulatory implications of cloud‐based live streaming,including issues with network neutrality,data privacy,and content moderation are *** future of cloud computing for live streaming is examined in the section that follows,and it looks at the most likely new developments in terms of trends and *** technology vendors,live streaming service providers,and regulators,the findings have major policy‐relevant *** on how stakeholders should address these concerns and take advantage of the potential presented by this rapidly evolving sector,as well as insights into the key challenges and opportunities associated with cloud‐based live streaming are provided.

关键词： cloud computing video analysis video coding

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