检索结果-南通市图书馆

Possible role of power-to-heat and power-to-gas as flexibleloads in German medium voltage networks

在线全文

学校读者我要写书评

暂无评论

Frontiers in Energy 2017年第2期11卷 135-145页

作者： Mark KUPRAT martin BENDIG Klaus PFEIFFER Forschungszentrum 3E LS EVH Siemens-Halske-Ring 13 03046Cottbus Germany

Germanys energy transition triggered a rapid and unilateral growth of renewable energy sources (REs) in the electricity sector. With increasing shares of intermittent REs, overcapacities during periods of strong wind and photovoltaic electricity generation occur. In the face of insufficient transmission capacities, due to an inhibited network extension, the electricity generation has to be curtailed. This curtailment of REs leads to economic losses and could be avoided through flexible loads. As an option to cope with those problems, the technologies of power-to-gas (PtG) and power-to-heat (PtH) are presented in this paper. First, the alkaline electrolyzer (AEL), polymer electrolyte membrane electrolyzer (PEMEL), and solid oxide electrolyzer cell (sOEC) are investigated regarding their operational parameters. second, the electric boiler, electrode heating boiler, and heat pumps are considered. Ultimately, the network-supporting abilities and the potential to provide ancillary services, such as control power, load sequence operation, cold start and part load capability, are compared among one another.

关键词： power-to-gas power-to-heat flexible loads ancillary services coherent energy systems

size effect on deuterium behavior in nano-sized vanadium layers

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

science China(Physics,Mechanics & Astronomy) 2019年第11期62卷 109-114页

作者： Wen Huang martin Brischetto Bjorgvin Hjorvarsson state Key Laboratory of silicon Materials and school of Materials science and Engineering Zhejiang UniversityHangzhou 310027China Department of Physics and Astronomy Uppsala UniversityUppsala SE-75120Sweden Department of Materials science and Engineering University of WashingtonSeattle WA 98195-2120USA

size effect on thermodynamics and diffusion of deuterium in nano-sized vanadium(V) layers is studied. Critical temperature(Tc)for deuterium phase transition is found to decrease with the inverse thickness of V layers and the thermodynamic factor increases as V thickness decreases. These effects are related to the deuterium-deuterium(D-D) interaction change versus V thickness,which experimentally proves that the D-D interaction plays the main contribution to the previously observed V size effect on deuterium chemical diffusion coefficients(D_c). The self-diffusion coefficients(D_s) are obtained through correcting D_c with the thermodynamic factors. It is found that the D_s are similar in 14 and 28 monolayers of V while slightly larger D_s are observed at high concentrations in 14 atomic layers. The weak site blocking effect in the interface is argued to be the main contribution to the observed size effect on D_s.

关键词： size effect D-D interaction deuterium diffusion Fe/V superlattice optical transmission

Numerical Noise Prediction in Fluid Machinery

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal science 2005年第3期14卷 230-235,248页

作者： Iris PANTLE Franco MAGAGNATO martin GABI Department of Fluid Machinery University of Karlsruhe D-76128 Karlsruhe Department of Fluid Machinery University of Karlsruhe D-76128 Karlsruhe Department of Fluid Machinery University of Karlsruhe D-76128 Karlsruhe

Numerical methods successively became important in the design and optimization of fluid machinery. However, as noise emission is considered, one can hardly find standardized prediction methods combining flow and acoustical optimization. several numerical field methods for sound calculations have been developed. Due to the complexity of the considered flow, approaches must be chosen to avoid exhaustive computing. In this contribution the noise of a simple propeller is investigated. The configurations of the calculations comply with an existing experimental setup chosen for evaluation. The used in-house CFD solver sPARC contains an acoustic module based on Ffowcs Williams-Hawkings Acoustic Analogy. From the flow results of the time dependent Large Eddy simulation the time dependent acoustic sources are extracted and given to the acoustic module where relevant sound pressure levels are calculated. The difficulties, which arise while proceeding from open to closed rotors and from gas to liquid are discussed.

关键词： numerical noise prediction fluid machinery computational aero-acoustics large eddy simulation

Empirical Model for the Quantitative Prediction of Losses of Radial Fans based on CFD Calculations

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal science 2013年第4期22卷 304-310页

作者： Heiko Ratter saban Caglar martin Gabi Institute of Fluid Machinery Karlsruhe Institute of Technology Kaiserstrasse 1276131 Karlsruhe Germany

In a classical layout process of a fan the quantity of losses is estimated as a sum and expressed in the overall efficiency rote However the characteristic of the pressure rise, the losses and the efficiency rate beside the design point is not known. Against this background a numerical model was developed to calculate quantitative values of occurring losses at radial fan impellers at an early stage in the design process. It allows to estimate the pressure rise and efficiency rate of a given fan geometry at and beside the design point. The physics of losses are described in literature, but obtaining quantitative values is still a challenge. As common in hydraulic theory the losses are calculated with analytic formulas supported by coefficients and efficiency rates, which have to be determined empirically. This paper shows the method how to determine the coefficients for a given radial fan. Therefore a representative radial fan with backward curved blades was designed in reference to classical design guidelines. Performance measuring was done conform to IsO 5801. The flow was calculated at 8 different operation points using CFD methods. The RANs equations are solved by using the ssT-k-omega turbulence model. The flow do- main consists of one blade section including inlet channel and outflow chamber. spatial discretization is done by a block-structured mesh of approx. 1.8 million cells. Performance data show a very good agreement between measurement and calculation.

关键词： loss model radial fan CFD RANs

Epididymosomes： transfer of fertility-modulating proteins to the sperm surface

在线全文

学校读者我要写书评

暂无评论

Asian Journal of Andrology 2015年第5期17卷 720-725,I0006页

作者： Patricia A martin-DeLeon Department of Biological sciences University of Delaware Newark DE 19716 USA

A variety of glycosylphosphatidylinositol （GPI）-linked proteins are acquired on spermatozoa from epididymal luminal fluids （ELF） during sperm maturation. These proteins serve roles in immunoprotection and in key steps of fertilization such as capacitation, acrosomal exocytosis and sperm-egg interactions. Their acquisition on sperm cells is mediated both by membrane vesicles （epididymosomes, EP） which were first reported to dock on the sperm surface, and by lipid carriers which facilitate the transfer of proteins associated with the membrane-free fraction of ELF. While the nonvesicular fraction is more efficient, both pathways are dependent on hydrophobic interactions between the GPI-anchor and the external lipid layer of the sperm surface. More recently proteomic and hypothesis-driven studies have shown that EP from several mammals carry transmembrane （TM） proteins, including plasma membrane Ca^2＋-ATPase 4 （PMCA4）. synthesized in the testis, PMCA4 is an essential protein and the major Ca^2＋ efflux pump in murine spermatozoa. Delivery of PMCA4 to spermatozoa from bovine and mouse EP during epididymal maturation and in vitro suggests that the docking of EP on the sperm surface precedes fusion, and experimental evidence supports a fusogenic mechanism for TM proteins. Fusion is facilitated by CD9, which generates fusion-competent sites on membranes. On the basis of knowledge of PMCA4＇s interacting partners a number of TM and membrane-associated proteins have been identified or are predicted to be present, in the epididymosomal cargo deliverable to spermatozoa. These Ca^2＋-dependent proteins, undetected in proteomic studies, play essential roles in sperm motility and fertility, and their detection highlights the usefulness of the hypothesis-driven approach.

关键词： epididymal maturation epididymal secretory proteins GPI-linked proteins lipid carrier membrane-associated proteins PMCA4 transmembrane proteins

EXCEPTIONALLY HIGH AND DIVERsE MUTATION RATEs IN INsECTs sMALL rRNA

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

science China Chemistry 1985年第10期28卷 1060-1063页

作者：冯亚雄 KRUPP GUIDO gross J.HANs Academia siaica Institut für Biochemie der Universitt Würzburg shanghai Institute of Biochemistry D-8700 Würzburg FRG Rontgenring 11

The nucleotide sequence of 5s rRNA from the posterior silk gland of the silk worm Philosamia cynthia ricini has been determined. The comparison with other insect 5s rRNAs revealed an exceptionally conserved secondary structure, in spite of an extremely high mutation rate: Thirteen nucleotides are different in Philosamia and Drosophila 5s rRNA, but all substitutions are either compensatory or occur in loops or introduce G:U base pairs. The rates of base substitution per site per year of several insect species (diptera and lepidoptera) 5s and 5.8s rRNAs are compared with those occurring in vertebrate rRNAs. In the latter cases the rates are remarkably constant, whereas their value is not only about twofold higher in insect rRNAs, but is found to be extremely large in the 5s rRNA of the silkworm Bombyx mori. These data demonstrate that phylogcnetic conclusions derived from small rRNA sequence comparisons are only of limited value.

关键词： EXCEPTIONALLY HIGH AND DIVERsE MUTATION RATEs IN INsECTs sMALL rRNA rate

Dredging effects on selected nutrient concentrations and ecoenzymatic activity in two drainage ditch sediments in the lower Mississippi River Valley

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International soil and Water Conservation Research 2017年第3期5卷 190-195页

作者： Matt Moore martin A.Locke Michael Jenkins Robert W.steinriede Daniel s.McChesney UsDA-Agricultural Research service National Sedimentation Laboratory598 McElroy DriveOxfordMS 38655USA

Agricultural drainage ditches are conduits between production acreage and receiving aquatic *** overlooked for their mitigation capabilities,agricultural drainage ditches provide an important role for nutrient transformation via microbial *** in ecoenzyme activities have been used to elucidate microbial metabolism and resource demand of microbial communities to better understand the relationship between altered nutrient ratios and microbial activity in aquatic *** agricultural drainage ditches,one in the northeast portion of the Arkansas Delta and the other in the lower Mississippi Delta,were monitored for a *** samples were collected prior to each ditch being dredged(cleaned),and subsequent post-dredging samples occurred as soon as access was *** samples were then collected throughout a year to examine effects of dredging on selected nutrient concentrations and ecoenzymatic activity recovery in drainage ditch *** concentrations in sediments after dredging decreased 33–66%,depending on ditch and phosphorus extraction ***,ecoenzymatic activity was significantly decreased in most sediment samples after *** diacetate hydrolysis activity,an estimate of total microbial activity,decreased 56–67%after dredging in one of the two *** sample sites also had significant phosphorus and ecoenzymatic activity differences between the post-dredge samples and the year-long follow-up *** indicate microbial metabolism in dredged drainage ditches may take up to a year or more to recover to pre-dredged ***,while sediment nutrient concentrations may be decreased through dredging and removal,runoff and erosion events over time tend to quickly replenish nutrient concentrations in replaced *** nutrient dynamics and microbial metabolism within agricultural drainage ditches is a crucial step toward addressing issues of nutri

关键词： Phosphorus FDA Denitrification Mehlich III Microbial Metabolism

Is there more than one stickiness criterion?

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Friction 2023年第6期11卷 1027-1039页

作者： Anle WANG martin H.MüsER Department of Material science and Engineering Saarland UniversitySaarbrücken66123Germany INM—Leibniz Institute for New Materials Saarbrücken66123Germany

Adhesion between an elastic body and a smooth,rigid substrate can lead to large tensile stresses between ***,most macroscopic objects are microscopically rough,which strongly suppresses adhesion.A fierce debate has unfolded recently as to whether local or global parameters determine the crossover between small and large ***,we report simulations revealing that the dependence of the pull-off force Fn on the surface energyγdoes not only have two regimes of high and low adhesion but up to four *** are related to contacts,which at the moment of rupture consist of(i)the last individual Hertzian-shaped contact,in which is linear inγ,(ii)a last meso-scale,individual patches with super-linear scaling,(iii)many isolated contact patches with extremely strong scaling,and(iv)a dominating largest contact patch,for which the pull-off stress is no longer negligible compared to the maximum,microscopic pull-off ***(iii)can be seen as a transition *** is located near the point where the surface energy is half the elastic energy per unit area in conformal contact.A criterion for the transition between regimes(i)and(ii)appears difficult to grasp.

关键词： adhesion pull-off force rough contact stickiness

The Bisq decentralised exchange: on the privacy cost of participation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Blockchain(Research and Applications) 2022年第1期3卷 13-22页

作者： Liam Hickey martin Harrigan Institute of Technology CarlowR93 V960Ireland

The Bisq Trade Protocol and the Bisq DAO(decentralised autonomous organisation)are core components of Bisq,a decentralised cryptocurrency *** Bisq Trade Protocol systematises the peer-to-peer trading of Bitcoin for other currencies and the Bisq DAO decentralises the governance and finance functions of the entire ***,by following the Bisq Trade Protocol and interacting with the Bisq DAO,participants necessarily publish data to the Bitcoin blockchain and broadcast additional data to the Bisq peer-to-peer *** examine the privacy cost to participants in sharing this ***,we use novel address clustering heuristics to construct the one-to-many mappings from participants to addresses on the Bitcoin blockchain and augment the address clusters with data stored within the Bisq peer-to-peer *** describe address clustering heuristics for both the Bisq Trade Protocol and the Bisq *** show that the heuristics aggregate activity performed by each participant:trading,voting,transfers,*** identify instances where participants are operating under multiple aliases,some of which are real-world *** identify the dominant transactors and their role in a two-sided *** conclude with suggestions to better protect the privacy of participants in the future.

关键词： Decentralised exchange Blockchain analysis Decentralised governance Cryptocurrency Privacy