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Overall Assessment of Heat Transfer for a Rarefied Flow in a Microchannel with Obstacles Using Lattice Boltzmann Method

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工程与科学中的计算机建模(英文) 2024年第1期138卷 273-299页

作者： Siham Hammid Khatir Naima Omolayo M.Ikumapayi cheikh Kezrane Abdelkrim Liazid Jihad Asad Mokdad Hayawi Rahman Farhan Lafta Rashid Naseer Ali Hussien Younes menni Laboratory of Development in Mechanics and Materials(LDMM) Zian Achour UniversityDjelfaPB 3117Algeria Department of Technology University Center Salhi Ahmed Naama(Ctr.Univ.Naama)P.O.Box 66Naama45000Algeria Department of Mechanical and Mechatronics Engineering Afe Babalola University Ado Ekiti360101Nigeria Departement of Physics Faculty of ScienceAbou Bekr Belkaid UniversityTlemcen13000Algeria Department of Physics Faculty of Applied SciencesPalestine Technical University-KadoorieTulkarmPalestine Aeronautical Technical Engineering Al-Farahidi UniversityBaghdad10011Iraq Mechanical Engineering Department University of KerbalaKarbala56001Iraq Information and communication Technology Research Group Scientific Research CenterAl-Ayen UniversityThi-QarIraq National University of Science and Technology Dhi QarIraq

The objective of this investigation is to assess the effect of obstacles on numerical heat transfer and fluid flow momentum in a rectangular microchannel(Mc).Two distinct configurations were studied:one without obstacles and the other with alternating obstacles placed on the upper and lower *** research utilized the thermal lattice Boltzmann method(LBM),which solves the energy and momentum equations of fluids with the BGK approximation,implemented in a Python coding *** jump and slip velocity conditions were utilized in the simulation for the Mc and extended to all obstacle *** study aims to analyze the rarefaction effect,with Knudsen numbers(Kn)of 0.012,0.02,and *** outcomes indicate that rarefaction has a significant impact on the velocity and temperature *** presence of nine obstacles led to slower fluid movement inside the microchannel Mc,resulting in faster cooling at the *** Mcs with obstacles,the rarefaction effect plays a crucial role in decreasing the Nusselt number(Nu)and skin friction coefficient(cf).Furthermore,the study demonstrated that the obstacles played a crucial role in boosting fluid flow and heat transfer in the *** findings suggest that the examined configurations could have potential applications as cooling technologies in micro-electro-mechanical systems and microdevice applications.

关键词： Microfluid rarefied flow LBM microchannel Knudsen number numerical simulation

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3D numerical study and comparison of thermal-flow performance of various annular finne d-tub e designs

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Journal of Ocean Engineering and Science 2023年第3期8卷 294-307页

作者： Farouk Tahrour Hijaz Ahmad Houari Ameur Tareq Saeed Hanaa Abu-Zinadah Younes menni Department of Physics Faculty of SciencesUniversity Mohamed Boudiaf of M’silaM’silaAlgeria Near East University Operational Research Center in HealthcareNear East BoulevardPC:99138 Nicosia/Mersin 10Turkey Section of Mathematics International Telematic University UninettunoCorso Vittorio Emanuele II3900186 RomaItaly Department of Technology University Centre of Naama-Ahmed SalhiP.O.Box 66Naama 45000Algeria Nonlinear Analysis and Applied Mathematics Research Group(NAAM) Mathematics DepartmentKing Abdulaziz UniversityJeddah 21589Saudi Arabia University of Jeddah College of ScienceDepartment of StatisticsJeddahSaudi Arabia

With the increase of heat transfer problems in marine vehicles and submerged power stations in oceans,the search for an efficient finned-tube heat exchanger has become particularly *** purpose of the present investigation is to analyze and compare the thermal exchange and flow characteristics between five different fin designs,namely:a concentric circular finned-tube(ccFT),an eccentric circular finned-tube(EcFT),a perforated circular finned-tube(PcFT),a serrated circular finned-tube(ScFT),and a star-shaped finned-tube(S-SFT).The fin design and spacing impact on the thermal-flow performance of a heat exchanger was computed at Reynolds numbers varying from 4,300 to 15,*** the numerical results,and when the fin spacing has been changed from 2 to 7 mm,an enhancement in the colburn factor and a reduction in the friction factor and fin performances were observed for all cases under *** criteria were checked to select the most efficient fin design:the performance evaluation criterion P Ec,the global performance criterion G Pc,and the mass global performance criterion M G *** the value of Reynolds number,the conventional ccFT provided the lowest performance evaluation criterion P Ec,while the ScFT gave the highest amount of P *** most significant value of G Pc was reached with the EcFT;however,G Pc remained almost the same for ccFT,PcFT,ScFT,and *** terms of the mass global performance criterion,the S-SFT provides the highest M Gpc as compared with the full fins of ccFT(41-73%higher)and EcFT(29-54%higher).Thus,the heat exchanger with S-SFT is recommended to be used in the cooling of offshore energy systems.

关键词： Thermal-flow performance Eccentric fins Star-shaped fins Perforated fins Finned-tube designs

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脂质分析与心血管疾病风险的关系:基于人群的前瞻性Bruneck研究

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中华高血压杂志 2014年第4期22卷 399-399页

作者： Stegemann c Pechlaner R Willeit P Langley S Mangino M Mayr U menni c Moayyeri A Santer P Rungger G Spector TD Willeit J Kiechl S Mayr M 刘莉叶鹏

大多数心血管疾病风险严重程度无法用传统危险因素来解释。最近质谱分析技术的进步使得对成百上千种脂质进行定性和定量分析成为可能。通过质谱分析法进行分子脂质分析可提高心血管疾病的风险预测。方法和结果：从基于人群的前瞻性Brun... 详细信息

大多数心血管疾病风险严重程度无法用传统危险因素来解释。最近质谱分析技术的进步使得对成百上千种脂质进行定性和定量分析成为可能。通过质谱分析法进行分子脂质分析可提高心血管疾病的风险预测。方法和结果：从基于人群的前瞻性Bruneck研究（在2000年进行了基线资料评估）的685个血液样本中提取脂质。应用三重四极杆质谱仪，

关键词：心血管疾病脂质分析疾病风险人群质谱分析技术质谱分析法危险因素定量分析

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How far is the endoscopist to blame for a percutaneous endoscopic gastrostomy complication?

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World Journal of Gastrointestinal Surgery 2023年第5期15卷 940-952页

作者： George Stavrou Persefoni Gionga George chatziantoniou Georgios Tzikos Alexandra menni StavrosPanidis Anne Shrewsbury Katerina Kotzampassi Department of Surgery Aristotle University of ThessalonikiThessaloniki 54636Greece Department of Surgery Addenbrooke's HospitalCambridge CB22QQUnited Kingdom

BAcKGROUND Percutaneous endoscopic gastrostomy(PEG)is a well-established,minimally invasive,and easy to perform procedure for nutrition delivery,applied to individuals unable to swallow for various *** has a high technical success rate of insertion between 95%and 100%in experienced hands,but varying complication rates ranging from 0.4%to 22.5%of *** To discuss the existing evidence of major procedural complications in PEG,mainly focusing on those that could probably have been avoided,had the endoscopist been more experienced,or less self-confident in relation to the basic safety rules for PEG *** After a thorough research of the international literature of a period of more than 30 years of published“case reports”concerning such complications,we critically analyzed only those complications which were considered-after assessment by two experts in PEG performance working separately-to be directly related to a form of malpractice by the *** Malpractice by the endoscopist were considered cases of:Gastrostomy tubes passed through the colon or though the left lateral liver lobe,bleeding after puncture injury of large vessels of the stomach or the peritoneum,peritonitis after viscera damage,and injuries of the esophagus,spleen,and *** For a safe PEG insertion,the overfilling of the stomach and small bowel with air should be avoided,the clinician should check thoroughly for the proper trans-illumination of the light source of the endoscope through the abdominal wall and ensure endoscopically visible imprint of finger palpation on the skin at the center of the site of maximum illumination,and finally,the physician should be more alert with obese patients and those with previous abdominal surgery.

关键词： Percutaneous endoscopic gastrostomy complications Doctor responsibility

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cFD-Based Simulation and Analysis of Hydrothermal Aspects in Solar channel Heat Exchangers with Various Designed Vortex Generators

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computer Modeling in Engineering & Sciences 2021年第1期126卷 147-173页

作者： Mohamed Salmi Younes menni Ali J.chamkha HouariAmeur Rachid Maouedj Ahmed Youcef Department of Physics University of M’silaM’sila28000Algeria Laboratory of Physics and chemistry of Materials University of M’silaM’sila28000Algeria Unit of Research on Materials and Renewable Energies Department of PhysicsAbou Bekr Belkaid UniversityTlemcen13000Algeria Faculty of Engineering Kuwait College of Science and TechnologyDoha DistrictKuwait center of Excellence in Desalination Technology King Abdulaziz UniversityJeddah21589Saudi Arabia Department of Technology University Center of NaamaNaama45000Algeria Unite de Recherche en Energies Renouvelables en Milieu Saharien URERMSCentre de Developpement des Energies RenouvelablesCDERAdrar01000Algeria

The hydrothermal behavior of air inside a solar channel heat exchanger equipped with various shaped ribs is analyzed *** bottom wall of the exchanger is kept adiabatic,while a constant value of the temperature is set at the upper *** duct is equipped with a flat rectangular fin on the upper wall and an upstream V-shaped baffle on the lower ***,five hot wall-attached rib shapes are considered:trapezoidal,square,triangular pointing upstream(type Ⅰ),triangular pointing downstream(type Ⅱ),and equilateral-triangular(type Ⅲ)cross *** of the flow rates are also inspected for various Reynolds numbers in the turbulent regime(1.2×10^(4)-3.2×10^(4)).The highest performance(η)value is given for the Ⅱ-triangular rib case in all Re values,while the square-shaped ribs show a significant decrease in the η along the achieved Re *** η value at Remax is 2.567 for the Ⅱ-triangular roughness *** with the other simulated cases,this performance is decreased by about 3.768%in the case of Ⅰ-triangular ribs,15.249% in the case of Ⅲ-triangular ribs,20.802% in the case of trapezoidal ribs,while 27.541% in the case of square ribs,at the same ***,a comparison ismade with air-heat exchangers that have non-rough walls and contain cross-shaped VGs presented previously,in order to highlight the effectiveness of the rough surface presence in the baffled and finned *** obtained results indicated that the triangular-shaped rib(type Ⅱ)has the most significant hydrothermal behavior than the other *** indicates the necessity of roughness heat transfer surfaces for finned and baffled channels to improve significantly the performance of the air-heat exchangers they contain.

关键词： cFD heat exchanger vortex generators ribs hydrothermal aspects

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Simulating the Turbulent Hydrothermal Behavior of Oil/MWcNT Nanofluid in a Solar channel Heat Exchanger Equipped with Vortex Generators

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computer Modeling in Engineering & Sciences 2021年第3期126卷 855-889页

作者： Rachid Maouedj Younes menni Mustafa Inc Yu-Ming chu Houari Ameur Giulio Lorenzini Unite de Recherche en Energies Renouvelables en Milieu Saharien URERMSCentre de Developpement des Energies RenouvelablesCDERAdrar01000Algeria Department of Physics Unit of Research on Materials and Renewable EnergiesFaculty of SciencesAbou Bekr Belkaid UniversityTlemcen13000Algeria Department of Mathematics Science FacultyFirat UniversityElazig23119Turkey Department of Medical Research China Medical University HospitalChina Medical UniversityTaichung40402Taiwan Department of Mathematics Huzhou UniversityHuzhou313000China Hunan Provincial Key Laboratory of Mathematical Modeling and Analysis in Engineering Changsha University of Science&TechnologyChangsha410114China Department of Technology University Centre of NaamaNaama45000Algeria Department of Engineering and Architecture University of ParmaParco Area delle Scienze 181/AParma43124Italy

Re-engineering the channel heat exchangers(cHEs)is the goal of many recent studies,due to their great importance in the scope of energy transport in various industrial and environmental *** the internal geometry of the cHEs by using extended surfaces,i.e.,VGs(vortex generators),is the most common technique to enhance the efficiency of heat *** work aims to develop a newdesign of solar collectors to improve the overall energy *** study presents a new channel design by introducing *** FVM(finite volume method)was adopted as a numerical technique to solve the problem,with the use of Oil/MWcNT(oil/multi-walled carbon nano-tubes)nanofluid to raise the thermal conductivity of the flow *** study is achieved for a Re number ranging from12×10^(3) to 27×10^(3),while the concentration(φ)of solid particles in the fluid(Oil)is set to 4%.The computational results showed that the hydrothermal characteristics depend strongly on the flow patterns with the presence of VGs within the *** the Oil/MWcNT rates with the presence of VGs generates negative turbulent velocities with high amounts,which promotes the good agitation of nanofluid particles,resulting in enhanced great transfer rates.

关键词： channel heat exchanger forced-convection Oil/MWcNT nanofluid cFD vortex generators

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Buried bumper syndrome:A critical analysis of endoscopic release techniques

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World Journal of Gastrointestinal Endoscopy 2023年第2期15卷 44-55页

作者： Alexandra menni Georgios Tzikos George chatziantoniou Persefoni Gionga Theodosios S Papavramidis Anne Shrewsbury George Stavrou Katerina Kotzampassi Department of Surgery Aristotle University of ThessalonikiThessaloniki 54636Greece

Buried bumper syndrome(BBS)is the situation in which the internal bumper of the gastrostomy tube,due to prolonged compression of the tissues between the external and the internal bumper,migrates from the gastric lumen into the gastric wall or further,into the tract outside the gastric lumen,ending up anywhere between the stomach mucosa and the surface of the *** restricts liquid food from entering the stomach,since the internal opening is obstructed by gastric mucosal *** performed a comprehensive search of the PubMed literature to retrieve all the case-reports and case-series referring to BBS and its management,after which we focused on the endoscopic techniques for releasing the internal bumper to re-establish the functionality of the *** the“push”and the“push and pull T”techniques to the most sophisticated-using high tech instruments,all 10 published techniques have been critically analysed and the pros and cons presented,in an effort to optimize the criteria of choice based on maximum efficacy and safety.

关键词： Buried bumper syndrome Percutaneous endoscopic gastrostomy Endoscopic release techniques Review

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