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Enhancing Solar Photovoltaic Efficiency:A Computational Fluid Dynamics Analysis

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Energy Engineering 2025年第1期122卷 153-166页

作者： Rahool Rai Fareed HussainMangi Kashif Ahmed Sudhakar Kumaramsay Faculty of Mechanical and Automotive Engineering Universiti Malaysia Pahang Al-Sultan AbdullahPekan26600PahangMalaysia Faculty of Engineering Science&Technology Hamdard UniversityKarachi74600Pakistan Electrical Engineering Department SUKKUR IBA UniversitySukkur65200Pakistan berlin School of Business and Innovation BSBI Faculty of Computer Science and InformaticsBerlin12043Germany Automotive Engineering Centre University Malaysia Pahang Al Sultan AbdullahPekan26600PahangMalaysia Centre for Research in Advanced Fluid&Processes(Fluid Centre) Universiti Malaysia Pahang Al-Sultan Abdullah(UMPSA)Paya BesarKuantan26300PahangMalaysia

The growing need for sustainable energy solutions,driven by rising energy shortages,environmental concerns,and the depletion of conventional energy sources,has led to a significant focus on renewable *** energy,among the various renewable sources,is particularly appealing due to its abundant ***,the efficiency of commercial solar photovoltaic(PV)modules is hindered by several factors,notably their conversion efficiency,which averages around 19%.This efficiency can further decline to 10%–16%due to temperature increases during peak sunlight *** study investigates the cooling of PV modules by applying water to their front surface through Computational fluid dynamics(CFD).The study aimed to determine the optimal conditions for cooling the PV module by analyzing the interplay between water film thickness,Reynolds number,and their effects on temperature reduction and heat *** CFD analysis revealed that the most effective cooling condition occurred with a 5 mm thick water film and a Reynolds number of *** specific parameters were found to maximize the heat transfer and temperature reduction *** finding is crucial for the development of practical and efficient cooling systems for PV modules,potentially leading to improved performance and longevity of solar *** cooling fluids or advanced cooling techniques that might offer even better efficiency or practical benefits.

关键词： PV module efficiency water film thickness reynolds number CFD analysis PV/T renewable energy

Method of reduction of dimensionality in contact and friction mechanics:A linkage between micro and macro scales

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Friction 2013年第1期1卷 41-62页

作者： Valentin L.POPOV berlin university of Technology Berlin 10623Germany

Computer simulations have been an integral part of the technical development process for a long time *** tribology is one of the last fields in which computer simulations have,until now,played no significant *** is primarily due to the fact that investigating tribological phenomena requires considering all spatial scales from the macroscopic shape of the contact system down to the *** the present paper,we give an overview of the previous work on the so-called method of reduction of dimensionality(MRD),which in our opinion,gives a key for the linking of the micro-and macro-scales in tribological *** in contact mechanics is based on the mapping of some classes of three-dimensional contact problems onto one-dimensional contacts with elastic *** equivalence of three-dimensional systems to those of one-dimension is valid for relations of the indentation depth and the contact force and in some cases for the contact *** arbitrary bodies of revolution,MRD is exact and provides a sort of“pocket edition”of contact mechanics,giving the possibility of deriving any result of classical contact mechanics with or without adhesion in a very simple way.A tangential contact problem with and without creep can also be mapped exactly to a one-dimensional *** can be shown that the reduction method is applicable to contacts of linear visco-elastic bodies as well as to thermal effects in *** method was further validated for randomly rough self-affine surfaces through comparison with direct 3D *** means a huge reduction of computational time for the simulation of contact and friction between rough surfaces accounting for complicated rheology and *** MRD,not only is the dimension of the space reduced from three to one,but the resulting degrees of freedom are independent(like normal modes in the theory of oscillations).Because of this independence,the method is predestinated for parallel calculation on

关键词： contact mechanics rough surfaces static friction sliding friction elastomers adhesion rolling dynamic tangential contacts reduction of dimensionality scale linkage

Reduction of friction by normal *** of contact stiffness

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Friction 2017年第1期5卷 45-55页

作者： M.POPOV V.L.POPOV N.V.POPOV berlin university of Technology Berlin 10623 GermanyTomsk Polytechnic University Tomsk 634050 RussiaTomsk State University Tomsk 634050 Russia berlin university of Technology Berlin 10623 Germany

The present paper is devoted to a theoretical analysis of sliding friction under the influence of oscillations perpendicular to the sliding *** contrast to previous works we analyze the influence of the stiffness of the tribological contact in detail and also consider the case of large oscillation amplitudes at which the contact is lost during a part of the oscillation period,so that the sample starts to 'jump'.It is shown that the macroscopic coefficient of friction is a function of only two dimensionless parameters-a dimensionless sliding velocity and dimensionless oscillation *** function in turn depends on the shape of the contacting *** the present paper,analysis is carried out for two shapes:a flat cylindrical punch and a parabolic *** we consider 'stiff systems',where the contact stiffness is small compared with the stiffness of the *** role of the system stiffness will be studied in more detail in a separate paper.

关键词： sliding friction out-of-plane oscillation contact stiffness coefficient of friction active control of friction

Ensuring federated learning reliability for infrastructure-enhanced autonomous driving

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Journal of Intelligent and Connected Vehicles 2023年第3期6卷 125-135页

作者： Benjamin Acar Marius Sterling Technical university of berlin Berlin10623Germany

The application of machine learning techniques,particularly in the context of autonomous driving solutions,has grown exponentially in recent *** such,the collection of high-quality datasets has become a prerequisite for training new ***,concerns about privacy and data usage have led to a growing demand for decentralized methods that can be learned without the need for pre-collected *** learning(FL)offers a potential solution to this problem by enabling individual clients to contribute to the learning process by sending model updates rather than training *** Federated Learning has proven successful in many cases,new challenges have emerged,especially in terms of network availability during *** a global instance is responsible for collecting updates from local clients,there is a risk of network downtime if the global server *** this study,we propose a novel and crucial concept that addresses this issue by adding redundancy to our *** than deploying a single global model,we deploy a multitude of global models and utilize consensus algorithms to synchronize and keep these replicas *** utilizing these replicas,even if the global instance fails,the network remains *** a result,our solution enables the development of reliable Federated Learning systems,particularly in system architectures suitable for infrastructure-enhanced autonomous ***,our findings enable the more effective realization of use cases in the context of cooperative,connected,and automated mobility.

关键词： federated learning(FL) Kubernetes autonomous driving

Hemagglutinin-esterase-fusion （HEF） protein of influenza C virus

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Protein & Cell 2016年第1期7卷 28-45页

作者： MingyangWang Michael Veilt Institute of Virology Veterinary Medicine Free University BerLin BerLin Germany

Influenza C virus, a member of the Orthomyxoviridae family, causes flu-like disease but typically only with mild symptoms. Humans are the main reservoir of the virus, but it also infects pigs and dogs. Very recently, influenza C-like viruses were isolated from pigs and cattle that differ from classical influenza C virus and might constitute a new influenza virus genus. Influenza C virus is unique since it contains only one spike protein, the hemagglu- tinin-esterase-fusion glycoprotein HEF that possesses receptor binding, receptor destroying and membrane fusion activities, thus combining the functions of Hemaggiutinin （HA） and Neuraminidase （NA） of influenza A and B viruses. Here we briefly review the epidemiology and pathology of the virus and the morphology of virus particles and their genome. The main focus is on the structure of the HEF protein as well as on its co- and post- translational modification, such as N-glycosylation, disulfide bond formation, S-acylation and proteolytic cleavage into HEF1 and HEF2 subunits. Finally, we describe the functions of HEF： receptor binding, esterase activity and membrane fusion.

关键词： influenza C virus HEF structure receptorbinding esterase membrane fusion

Impact of Industry 4.0 in service oriented firm

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Advances in Manufacturing 2017年第4期5卷 394-400页

作者： Wladimir Bodrow Department Business Informatics University of Applied Sciences Berlin Berlin 10318 Germany

The first part of this study is devoted to concepts, approaches and some examples of the fourth industrial revolution. The basis of this revolution also well known as Industry 4.0 builds so called cyber-physical systems. They contain the integrated smart software systems including the internet address to enable the communication with envi- ronment as for product itself as for means of production and employees. All these enable the next level of efficiency and flexibility for both organizing and controlling of the value-creation chain over the whole lifecycle of products. In the first three chapters several Internet references and documents published by German Federal Ministry for Economic Affairs and Energy were used. Because of multiple cross references in documents, this report is written without detailed references in each paragraph of mentioned chapters. The last three chapters of the research presented undertake the short review of interdependencies between the Industry 4.0 and the well-known approach of computer-supported-cooperative-work established in the late 1980s. Long list of publications can be found in Wikipedia, and in many proceedings of ACM conferences on computer supported cooperative work （CSCW）.

关键词： Fourth industrial revolution Industry 4.0 Cyber-physical system. Smart production Computer supported cooperative work (CSCW)

Surface tracking assessment and interaction in texture space

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Computational Visual Media 2018年第1期4卷 3-15页

作者： Johannes Furch Anna Hilsmann Peter Eisert Fraunhofer HHI Berlin10587Germany Humboldt university Berlin10099Germany

In this paper, we present a novel approach for assessing and interacting with surface tracking algorithms targeting video manipulation in postproduction. As tracking inaccuracies are unavoidable,we enable the user to provide small hints to the algorithms instead of correcting erroneous results afterwards. Based on 2D mesh warp-based optical flow estimation, we visualize results and provide tools for user feedback in a consistent reference system, texture space. In this space, accurate tracking results are reflected by static appearance, and errors can easily be spotted as apparent change. A variety of established tools can be utilized to visualize and assess the change between frames. User interaction to improve tracking results becomes more intuitive in texture space, as it can focus on a small region rather than a moving *** show how established tools can be implemented for interaction in texture space to provide a more intuitive interface allowing more effective and accurate user feedback.

关键词： surface tracking assessment interaction mesh warp optical flow

Reduction of friction by normal oscillations.Ⅱ.In-plane system dynamics

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Friction 2017年第2期5卷 534-535,536页

作者： Xinyu MAO Valentin L.POPOV Jasminka STARCEVIC Mikhail POPOV Technische Universit(a)t berlin Berlin 10623 GermanyTsinghua University Beijing 100084 China Technische Universit(a)t berlin Berlin 10623 GermanyTomsk Polytechnic University Tomsk 634050 RussiaTomsk State University Tomsk 634050 Russia Technische Universit(a)t berlin Berlin 10623 GermanyTomsk State University Tomsk 634050 Russia

The influence of out-of-plane oscillations on friction is a well-known phenomenon that has been studied extensively with various experimental methods,e.g.,pin-on-disk ***,existing theoretical models have yet achieved only qualitative correspondence with *** we argue that this may be due to the system dynamics (mass and tangential stiffness) of the pin or other system components being *** paper builds on the results of a previous study [19] by taking the stiffness and resulting dynamics of the system into *** main governing parameters determining macroscopic friction,including a dimensionless oscillation amplitude,a dimensionless sliding velocity and the relation between three characteristic frequencies (that of externally excited oscillation and two natural oscillation frequencies associated with the contact stiffness and the system stiffness) are *** the limiting cases of a very soft system and a very stiff system,our results reproduce the results of previous *** between these two limiting cases there is also a resonant case,which is studied here for the first *** resonant case is notable in that it lacks a critical sliding velocity,above which oscillations no longer reduce *** obtained for the resonant case are qualitatively supported by experiments.

关键词： sliding friction out-of-plane oscillation stiffness system dynamics macroscopic friction coefficient

Phosphorus recovery from municipal and fertilizer wastewater:China's potential and perspective

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Journal of Environmental Sciences 2017年第2期29卷 151-159页

作者： Kuangxin Zhou Matthias Barjenbruch Christian Kabbe Goulven Inial Christian Remy berlin Centre of Competence for Water Berlin 10709Germany Department of Urban Water Management Technical University of BerlinBerlin 13355Germany Research&Innovation Asia Veolia EnvironmentBeijing 10004China

Phosphorus（P） is a limited resource, which can neither be synthesized nor substituted in its essential functions as nutrient. Currently explored and economically feasible global reserves may be depleted within generations. China is the largest phosphate fertilizer producing and consuming country in the world. China’s municipal wastewater contains up to 293,163 Mg year of phosphorus, which equals approximately 5.5% of the chemical fertilizer phosphorus consumed in China. Phosphorus in wastewater can be seen not only as a source of pollution to be reduced, but also as a limited resource to be recovered. Based upon existing phosphorus-recovery technologies and the current wastewater infrastructure in China, three options for phosphorus recovery from sewage sludge, sludge ash and the fertilizer industry were analyzed according to the specific conditions in China.

关键词： Phosphorus recovery Municipal Wastewater Fertilizer Industry Sewage sludge China