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Photovoltaic yield prediction using an irradiance forecast model based on multiple neural networks

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Journal of Modern Power Systems and Clean Energy 2018年第2期6卷 255-267页

作者： Saad Parvaiz DURRANI stefan BALLUFF Lukas WURZER stefan KRAUTER Paderborn University Bosch Thermotechnik GmbH

In order to develop predictive control algorithms for efficient energy management and monitoring for residential grid connected photovoltaic systems, accurate and reliable photovoltaic(PV) power forecasts are required.A PV yield prediction system is presented based on an irradiance forecast model and a PV model. The PV power forecast is obtained from the irradiance forecast using the PV model. The proposed irradiance forecast model is based on multiple feed-forward neural networks. The global horizontal irradiance forecast has a mean absolute percentage error of 3.4% on a sunny day and 23% on a cloudy day for Stuttgart. PV power forecasts based on the neural network irradiance forecast have performed much better than the PV power persistence forecast model.

关键词： Grid connected photovoltaic(GCPV) Photovoltaic(PV) PV power prediction Irradiance forecast Neural network(NN)

Galerkin Spectral Method Applied to the Chemical Master Equation

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Communications in Computational Physics 2009年第5期5卷 871-896页

作者： stefan Engblom Department of Information Technology Uppsala UniversityP.O.Box 337SE-75105 UppsalaSweden

Stochastic well-stirred chemically reacting systems can be accurately modeled by a continuous-time *** corresponding master equation evolves the system’s probability density function in time but can only rarely be explicitly *** investigate a numerical solution strategy in the form of a spectral method with an inherent natural adaptivity and a very favorable choice of basis *** results related to convergence have been developed previously and are briefly summarized while implementation issues,including how to adapt the basis functions to follow the solution they represent,are covered in more detail *** method is first applied to a model problem where the convergence can easily be *** we take on two more realistic systems from molecular biology where stochastic descriptions are often necessary to explain experimental *** conclusion is that,for sufficient accuracy demands and not too high dimensionality,the method indeed provides an alternative to other methods.

关键词： Master equation spectral-Galerkin method high dimensional problem moving basis chemical reactions

Role of Omicron variant of SARS-CoV-2 in children in Germany

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World Journal of Pediatrics 2022年第4期18卷 283-284页

作者： stefan Bittmann Department of Pediatrics Medical and Finance Center EpePed Mind Institute(PMI)Hindenburgring 448599 GronauGermany

A new variant of SARS-CoV-2,B.1.1.529 was first reported by the South African Department of Health on Nov 24,*** new variant was named as B.1.1.529 Omicron and was classified as a variant of concern(VOC)by the World Health Organization(WHO)on Nov 26,2021[1-13],Phylogenetic studies showed that Omicron arose independently of the currently dominant delta *** has an unusually high number of approximately 30 changes of amino acids in the spike protein compared with the original SARS-CoV-2,including those with known phenotypic impact(increase in transmission,immune evasion,and transmissibility),but significances of many mutations are still unclear[4-7].

关键词： Omi Phylogenetic children

Current treatment options and response rates in children with chronic hepatitis C

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World Journal of Gastroenterology 2012年第2期18卷 99-104页

作者： stefan Wirth Helios Medical Centre Wuppertal Department of PediatricsWitten-Herdecke UniversityD-42283 WuppertalGermany

Vertical transmission has become the most common mode of transmission of hepatitis C virus (HCV) in *** rate of perinatal transmission from an HCVinfected mother to her child ranges from 2% to 5% and the prevalence of HCV in children in developed countries ranges between 0.1% and 0.4%.Spontaneous viral clearance seems to be dependent on the genotype and has been reported between 2.4%-25%.For chronically infected patients,treatment with recombinant polyethylene glycol (PEG)-interferon α-2b and daily ribavirin has now been approved as standard treatment for children 2-17 years of *** five large prospective studies,a total of 318 children and adolescents aged 3-17 years were treated either with subcutaneous PEG-interferon α-2b at a dose of 1-1.5 μg/kg or 60 μg/m2 once a week in combination with oral ribavirin (15 mg/kg per day) or PEG-interferon α-2a with *** with genotype 1 and 4 received the medication for 48 wk and individuals with genotype 2 and 3 mainly for 24 *** sustained viral response (SVR) was achieved in 193/318 (60.7%) of treated *** for genotype;120/234 (51%) with genotype 1,68/73 (93%) with genotype 2/3,and 6/11 (55%) with genotype 4 showed *** rate was between 7.7% and 17%.Overall,treatment was well tolerated;how-ever,notable side effects were present in approximately 20%.According to recent experiences in the treatment of chronic hepatitis C in children and adolescents,a combination of PEG-interferon α with ribavirin has been found to be well tolerated and highly efficacious,particularly in individuals with genotype 2/***,this treatment can be recommended as standard of care until more effective treatment options will become available for genotype 1 patients.

关键词： Chronic hepatitis C Treatment Children Polyethylene glycol-interferon and ribavirin Responserate

MP-PIC simulation of circulating fluidized beds using an EMMS based drag model for Geldart B particles

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Particuology 2021年第6期19卷 76-90页

作者： Timo Dymala Tom Wytrwat stefan Heinrich Hamburg University of Technology Institute of Solids Process Engineering and Particle TechnologyDenickestr.1521073 HamburgGermany

In this study the multiphase particle-in-cell(MP-PIC)method is used for the simulation of two pilot-scale circulating fluidized beds(CFBs)with quartz sand belonging to Geldart’s group B as bed *** simulations were performed using a homogeneous drag model as well as a structure dependent drag model based on the energy minimization multi-scale method(EMMS).The results are compared with experimental data from literature as well as *** simulations with the EMMS based drag model show a good agreement of the time-averaged axial solids concentration,circulation rate and riser pressure ***,a lower grid sensitivity is observed compared to the homogeneous drag *** contrast to the conventional drag model a dense bottom zone is predicted by the EMMS based drag *** overprediction of the solid concentration in the dense bottom zone is presumably due to an overprediction of the cluster diameter that is calculated using an empirical cluster diameter *** shows the necessity for a new meso-scale cluster correlation for the simulation of Geldart B ***,the results of the time-averaged radial solids concentration differ from the expectations of a core-annulus flow indicating that a mesh refinement at the walls is ***,the importance of using a realistic particle size distribution is identified.

关键词： 3D-CFD simulation Circulating fluidized bed(CFB) Multiphase particle-in-cell method(MP-PIC) Energy minimizing multi-scale theory(EMMS) Validation study

Influence of water evaporation on elastohydrodynamic lubrication with water-containing polyalkylene glycols

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Friction 2024年第10期12卷 2370-2388页

作者： stefan HOFMANN Thomas LOHNER Karsten STAHL Technical University of Munich School of Engineering and DesignDepartment of Mechanical EngineeringGear Research Center(FZG)Boltzmannstraße 1585748 Garching near MunichGermany

The reduction of frictional power losses in power transmitting gears takes a crucial role in the design of energy-and resource-efficient ***-containing lubricants like glycerol and polyalkylene glycols have shown great potential in achieving friction within the superlubricity regime with coefficients of friction lower than 0.01 under elastohydrodynamic ***,a bio-based production of the base stocks can lead to the development of green ***,one challenge associated with the application of water-containing lubricants to gearboxes is the evaporation of water and its impact on the lubricant *** this study,the influence of water evaporation on elastohydrodynamic friction and film thickness was investigated for three water-containing polyalkylene *** nominal water contents of 20 wt%and 40 wt%and two viscosities were *** results show that the friction increases continuously with higher evaporated water content,while the overall friction level remains low in nearly water-free states.A similar trend is observed for film thickness,where the strong increase in viscosity results in a notable increase in film ***,the sensitivity of friction and film thickness to water evaporation is low for small amounts of evaporated *** allows generous thresholds for permissible variations in water content.

关键词： friction superlubricity aqueous lubrication elastohydrodynamic lubrication(EHL) evaporation polyalkylene glycol

A Design Concept and Kinematic Model for a Soft Aquatic Robot with Complex Bio-mimicking Motion

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Journal of Bionic Engineering 2022年第1期19卷 16-28页

作者： Shokoofeh Abbaszadeh Roberto Leidhold stefan Hoerner Institute of Electrical Power Systems Department of Electrical Engineering and Information TechnologyOtto-Von-Guericke University of MagdeburgUniversitätsplatz 239106MagdeburgGermany Institute of Fluid Dynamics and Thermodynamics Department of Process and Systems EngineeringOtto-Von-Guericke University of MagdeburgUniversitätsplatz 239106MagdeburgGermany

Fish mortality assessments for turbine passages are currently performed by live-animal testing with up to a hundred thousand fish per year in Germany.A propelled sensor device could act as a fish *** this context,the study presented here investigates the state of the art via a thorough literature review on propulsion systems for aquatic *** evaluation of propulsion performance,weight,size and complexity of the motion achievable allows for the selection of an optimal concept for such a fish mimicking device carrying the *** the second step,the design of a bioinspired soft robotic fish driven by an unconventional drive system is *** is based on piezoceramic actuators,which allow for motion with five degrees of freedom(DOF)and the creation of complex bio-mimicking body motions.A kinematic model for the motion’s characteristics is developed,to achieve accurate position feedback with the use of strain *** measurements validate the complex deformation of the body and deliver the basis for the calibration of the kinematic ***,it can be shown,that the calibrated model presented allows the tracking of the deformation of the entire body with an accuracy of 0.1 mm.

关键词： Unconventional drive system Biologically inspired robots Biomimetics Flexible robots

Exploring Content Popularity in Information-Centric Networks

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China Communications 2015年第7期12卷 13-22页

作者： Andriana Ioannou stefan Weber School of Computer Science and Statistics Trinity College

Information-Centric Networking(ICN), an alternative architecture to the current Internet infrastructure, focuses on the distribution and retrieval of content by employing caches in a network to reduce network traffic. The employment of caches may be accomplished using graph-based and content-based criteria such as the position of a node in a network and content popularity. The contribution of this paper lies on the characterization of content popularity for on-path in-network caching. To this end, four dynamic approaches for identifying content popularity are evaluated via simulations. Content popularity may be determined per chunk or per object, calculated by the number of requests for a content against the sum of requests or the maximum number of requests. Based on the results, chunk-based approaches provide 23% more accurate content popularity calculations than object-based approaches. In addition, approaches that are based on the comparison of a content against the maximum number of requests have been shown to be more accurate than the alternatives.

关键词： network distributed architectures future internet information-centric networks caching technologies on-path caching content popularity

Support elements in conventional tunneling–Focus on long-term behavior

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Underground Space 2018年第4期3卷 277-287页

作者： Robert Galler stefan Lorenz Chair of Subsurface Engineering Department of Mineral Resources EngineeringMontanuniversita¨t LeobenP.O.Box 8700Erzherzog Johann Str.3LeobenAustria

Owing to increasing traffic and the need for constructing second tunnel tubes including corresponding cross-passages,where only one tube existed thus far,sampling of tunnel-lining materials with an age of 30–40 years has been made *** and in situ tests were carried out to evaluate the long-term effects of the tunnel *** paper presents the outcomes regarding the long-term behav-ior of support elements and membranes after performing strength tests on inner and outer lining concrete samples,flat jack tests,rock bolt tests,and tests on re-extracted sheet membranes,as well as ***,the interface connection mechanical behavior in a double-shell-lined tunnel was investigated with laboratory *** aim of this research was to determine the characteristics of sheet membranes and geotextiles in the case of reduced load-bearing capacity caused by degradation of the primary *** results provide information on the load-sharing effects of the interaction between the primary and secondary lining,depending on the waterproofing sheet membrane and geotextile *** on the results,conclusions for new design approaches for underground infrastructure construction can be formulated.

关键词： Tunnel lining Long-term behavior Concrete Sheet membrane Rock bolt Flat jack test In situ tests