检索结果-南通市图书馆

What does the future bring?A look at technologies for commercial aircraft in the years 2035-2050

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Propulsion and Power Research 2014年第4期3卷 165-174页

作者： meyer j.Benzakein The Ohio State University ColumbusOhio 43210United States

Demographics and economics in the next 20 years are being ex *** reflect a significant GDP growth and with this a strong demand for commercial aircraft not only in the US and Europe but across Asia and the Middle East The demand will focus on more fuel efficient and more environmentally friendly *** progress is being made with the new regionals,narrow-body,and wide-body aircraft between now and the year *** beyond,the world will examine new airplane architectures,new changes in propulsion systems,and higher thermal and propulsion *** propulsion options will come into *** them,higher operating pressure gas generators will be developed and great attention will have to be given to highly integrated propulsion/airplane *** transfer requirements will lead to bigger gear systems as well as new hybrid *** new machines are forecasted to offer improvements in fuel efficiencies of over 40%.There are many technical challenges to make all these things *** aerospace engineers and scientists of today and tomorrow face unlimited opportunities to make a difference for what looks like a very exciting future.

关键词： Fuel efficiency High bypassratio Distributed systems Turbines Propulsion Engines Airplane

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

基于优化算法的串联体系可靠度分析(英文)

计算力学学报 2004年第6期21卷 665-670页

作者：李刚 meyer j 大连理工大学工业装备结构分析国家重点实验室辽宁大连116024 科罗拉多州立大学化学工程系

结构体系的失效概率数学上可以表示为结构体系失效域上联合概率密度函数的积分,一般情况下很难直接积分求解。近几十年来,结构体系可靠度分析一直是可靠度领域的一个研究热点,人们提出许多方法,如:Monte-Carlo法、重要性抽样法与界限法... 详细信息

结构体系的失效概率数学上可以表示为结构体系失效域上联合概率密度函数的积分,一般情况下很难直接积分求解。近几十年来,结构体系可靠度分析一直是可靠度领域的一个研究热点,人们提出许多方法,如:Monte-Carlo法、重要性抽样法与界限法和概率网络估算技术等,这些算法在求解精度、计算效率、收敛性和易使用性等方面是不同的。本文采用优化算法(改进的可行方向法、序列线性规划和序列二次规划法)进行串联体系可靠度分析,并且与其他算法(HL-RF法、Monte-Carlo法和重要性抽样法)的结果以及一些精确解进行了比较。结果表明,相对于其他算法,基于优化算法的可靠度分析适用性广,在收敛性和健实性等方面具有明显的优势。

关键词：体系可靠度一次二阶矩法优化算法 Monte—Carlo法重要性抽样法

The impact of salps(Salpa thompsoni)on the Antarctic krill population(Euphausia superba):an individual-based modelling study

在线全文

学校读者我要写书评

暂无评论

Ecological Processes 2023年第1期12卷 680-695页

作者： Bruno Walter Pietzsch Aaron Schmidt jürgen Groeneveld Dominik Bahlburg Bettina meyer Uta Berger Faculty of Environmental Sciences Institute of Forest Growth and Forest Computer SciencesTechnische Universität Dresden01062 DresdenGermany Department of Ecological Modelling Helmholtz Centre for Environmental Research-UFZLeipzigGermany Section Polar Biological Oceanography Alfred Wegener Institute Helmholtz Centre for Polar and Marine ResearchBremerhavenGermany Institute for Chemistry and Biology of the Marine Environment(ICBM) Carl-Von-Ossietzky UniversityOldenburgGermany Helmholtz Institute for Marine Functional Biodiversity(HIFMB) OldenburgGermany

Background Krill(Euphausia superba)and salps(Salpa thompsoni)are key macrozooplankton grazers in the Southern Ocean ***,due to differing habitat requirements,both species previously exhibited little spatial *** ongoing climate change-induced seawater temperature increase and regional sea ice loss,salps can now extend their spatial distribution into historically krill-dominated areas and increase rapidly due to asexual reproduction when environmental conditions are *** the potential effects on krill is crucial,since krill is a species of exceptional trophic significance in the Southern Ocean food *** impacts on krill could trigger cascading effects on its predators and *** address this question,we combined two individual-based models on salps and krill,which describe the whole life cycle of salp individuals and the dynamic energy budget of individual *** resulting new model PEKRIS(PErformance of KRIll ***)simulates a krill population for 100 years under varying chlorophyll-a concentrations in the presence or absence of *** All of the investigated krill population properties(abundance,mean length,and yearly egg production)were significantly impacted by the presence of *** the other hand,salp density was not impacted if krill were *** medians of krill population properties deviated during variable maximum chlorophyll-a density per year when salps were introduced by−99.9%(−234 individuals per 1000 m3)for krill density,−100%(−22,062 eggs per 1000 m3)for krill eggs and−0.9%(−0.3 mm)for mean length of *** If both species compete for the same food resource in a closed space,salps seem to inhibit krill *** simulation studies should investigate whether this effect prevails if different phytoplankton sizes and consumption preferences of krill are ***,direct predation of the two species or consumption of krill fecal pellets by salps could c

关键词： Euphausia superba Salpa thompsoni Individual-based model Food competition Population dynamics DEB theory

同方期刊数据库

Investigations on the aging behavior of transparent bioplastics for optical applications

在线全文

学校读者我要写书评

暂无评论

InfoMat 2020年第2期2卷 424-433页

作者： jana Baltscheit Nico Schmidt Finn Schröder jörg meyer Photonics and Materials Science Hamm-Lippstadt University of Applied ScienceLippstadtGermany Department of Natural Science Paderborn UniversityPaderbornGermany

In this study,the optical properties of transparent bioplastics have been *** long-term technological goal is to establish biopolymers in a new market segment for demanding optical applications and to contribute to a more sustainable economy.A collection of transparent bioplastics has been tested with respect to the long-term stability and the possibility of an application in optical components for LED *** focus of materials testing was on the influence of short wavelength visible radiation as well as thermal *** results show,that some materials may be candidates for subsequent feasibility *** the best of our knowledge,the application of such polymers in complex technical products and in particular in luminaires has not yet been *** use of bio-based plastics for optical components therefore represents a novelty and has a high development potential.

关键词： (blue)LED irradiance (photo)degradation biobased plastics renewable materials transparent optics

Promoting electrochemical reduction of CO_(2) to ethanol by B/N-doped sp^(3)/sp^(2) nanocarbon electrode

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2022年第10期33卷 4691-4694页

作者： Yanming Liu Haolei Yang Xinfei Fan Bing Shan Thomas j.meyer Key Laboratory of Industrial Ecology and Environmental Engineering(Ministry of Education) School of Environmental Science and TechnologyDalian University of TechnologyDalian 116024China Department of Chemistry University of North Carolina at Chapel HillChapel HillNorth Carolina 27599United States College of Environmental Science and Engineering Dalian Maritime UniversityDalian 116026China

Electrochemical reduction of CO_(2) to value-added chemicals holds promise for carbon utilization and renewable electricity ***,selective CO_(2) reduction to multi-carbon fuels remains a significant ***,we report that B/N-doped sp^(3)/sp^(2) hybridized nanocarbon(BNHC),consisting of ultra-small nanoparticles with a sp^(3) carbon core covered by a sp^(2) carbon shell,is an efficient electrocatalyst for electrochemical reduction of CO_(2) to ethanol at relatively low ***_(2) reduction occurs with a Faradaic efficiency of 58.8%-69.1% for ethanol and acetate production at -0.5∼-0.6 V(***),among which 51.6%-56.0% is for *** high selectivity for ethanol is due to the integrated effect of sp^(3)/sp^(2) carbon and B/N *** sp^(3) carbon and B/N doping contribute to enhanced ethanol production with sp^(2) carbon reducing the overpotential for CO_(2) reduction to ethanol.

关键词： CO_(2)reduction Ethanol B/N-doped sp^(3)/sp^(2)hybridized nanocarbon Electrocatalysis multi-carbon product

Determination of particle exchange rates at over-flow weirs in horizontal fluidised beds by particle tracking velocimetry

在线全文

学校读者我要写书评

暂无评论

Particuology 2017年第3期15卷 1-9页

作者： Katja meyer Andreas Buck Evangelos Tsotsas Thermal Process Engineering Otto von Guericke University Magdeburg UniversitStsplatz 2 D-39106 Magdeburg Germany

Residence time distributions （RTDs） in horizontal fluidised beds have a huge effect on solid product properties and are infuenced by the internal design of the apparatus, e.g. the separation into different compartments by weirs. Weirs can be passed in or against the overall solid transport direction, with the back-flow resulting in axial dispersion, which is a measure of the spread of the RTD. Therefore, the ratio of exchange rates at weirs under different fluidisation conditions provides information on axial dispersion. In this work, a methodology based on particle tracking velocimetry is presented to obtain information on the exchange rates of particles at weirs in horizontal fluidised beds. The internal recirculation is studied for over-flow weirs with respect to different fluidisation conditions, providing a first step towards determining the effects of weirs and fluidisation conditions on axial dispersion and RTDs in horizontal fluidised beds.

关键词： Particle tracking velocimetry Horizontal fluidised bedAxial dispersion Granulation Drying

The contribution of small leaks in a baghouse filter to dust emission in the PM2.s range-A system approach

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Particuology 2017年第1期15卷 40-52页

作者： Oliver Kurtz jorg meyer Gerhard Kasper Institut for Mechanische Verfahrenstechnik und Mechanik Karlsruhe Institute of Technology 76131 Karlsruhe Germany Freudenberg Filtration Technologies 69465 WeinheimGermany.

The contribution of leakage in a baghouse filter （defined as a short circuit between the upstream and downstream sides of the filter） to the emission of fine particles is quantified in comparison to other dust emission sources, and the influence of key operating variables on overall system response is analyzed. The study was conducted on a well-maintained pilot-scale filter unit （9 bags of 500 g/m^2 calendered polyester needle felt; total surface area 4.2 m^2） operated in Ap-controlled mode over a range of pulsing intensities, with two types of test dust （one free-flowing and the other cohesive） at inlet concentrations of 10 and 30 g/m^3. Leaks included single holes between 0.5 and 4 mm diameter, intentionally placed in either the plenum plate or one of the filter bags, as well as seamlines from bag confectioning. Emissions were sep- arated by source into a transient contribution due to dust penetration through the filter bags after each cleaning pulse, and a continuous contribution from leaks. This separation was based on a novel method of data processing that relies on time-resolved concentration measurements with a specially calibrated optical particle counter. Tiny leaks on the order of 1 mm generated the same emission level as all the bags combined, and dominated continuous emissions. The equivalent leak cross section （leakage = media emission） was about 1 ppm of the total installed filter surface, independent of upstream dust concentra- tion. Leakage through open seamlines amounted to 75% of media emissions in case of free-flowing test dust. Leakage was restricted to aerodynamic diameters less than ~5 μm （roughly the PM2.s mass frac- tion）. For comparison, time-averaged mass penetration through conventional needle-felt media ranged from about 10^-5 to 10^-6, depending on cohesiveness of the particle material and pulse cleaning intensity, giving emission levels between about 0.02 and 0.2 mg/m^3 at the reference concentration of 10 R/m^2.

关键词： Air filtration Baghouse Pulse-cleaned filters Leaks PM2.5 Dust emission

Regeneration of adhesive tail pad scales in the New Zealand gecko (Hoplodactylus maculatus) (Reptilia, Squamata; Lacertilia) can serve as an experimental model to analyze setal formation in lizards generally

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Zoological Research 2017年第4期38卷 191-197页

作者： Lorenzo Alibardi Benno meyer-Rochow Comparative Histolab and Department of Bigea Dipartimento di Biologia University of Bologna Bologna 40126 Italy Research Institute of Luminous Organisms Tokyo 100-1623 Japan Department of Genetics and Physiology Oulu University Oulu FIN 90140 Finland

During the regeneration of the tail in the arboreal New Zealand gecko （Hoplodactylus maculatus） a new set of tail scales, modified into pads bearing setae 5-20 μm long, is also regenerated. Stages of the formation of these specialized scales from epidermal pegs that invaginate the dermis of the regenerating tail are described on the basis of light and electron microscopic images. Within the pegs a differentiating clear layer interfaces with the spinulae and setae of the Oberh^utchen according to a process similar to that described for the digital pads. A layer of clear cytoplasm surrounds the growing tiny setae and eventually comities around them and their spatular ends, later leaving the new setae free- standing on the epidermal surface. The fresh adhesive pads help the gecko to maintain the prehensile function of its regenerated tail as together with the axial skeleton （made of a cylinder of elastic cartilage） the pads allow the regenerated tail to curl around twigs and small branches just like the original tail. The regeneration of caudal adhesive pads represents an ideal system to study the cellular processes that determine setal formation under normal or experimental manipulation as the progressive phases of the formation of the setae can be sequentially analyzed.

关键词： Gecko lizard Regeneration Epidermis Tail pad scales Adhesion Prehensile function Ultrastructure

Pharmacologic inhibition of mTORC1 mimics dietary protein restriction in a mouse model of lactation

在线全文

学校读者我要写书评

暂无评论

journal of Animal Science and Biotechnology 2021年第2期12卷 729-738页

作者： Virginia L.Pszczolkowski Steven j.Halderson Emma j.meyer Amy Lin Sebastian I.Arriola Apelo Department of Animal and Dairy Sciences University of Wisconsin-MadisonMadisonWIUSA Endocrinology and Reproductive Physiology Graduate Training Program University of Wisconsin-MadisonMadisonWIUSA

Background:Understanding the mechanisms of N utilization for lactation can lead to improved requirement estimates and increased efficiency,which modern dairy diets currently fail to *** mechanistic target of rapamycin complex 1(mTORC1)is a central hub of translation regulation,processing extra-and intra-cellular signals of nutrient availability and physiological state,such as amino acids and *** hypothesized that dietary amino acids regulate lactation through mTORC1,such that inhibition of mTORC1 will lead to decreased lactation performance when amino acids are not *** objectives were to assess lactation performance in lactating mice undergoing dietary and pharmacologic interventions designed to alter mTORC1 ***:First lactation mice(N=18;n=6/treatment)were fed an adequate protein diet(18%crude protein),or an isocaloric protein-restricted diet(9%crude protein)from the day after parturition until lactation day 13.A third group of mice was fed an adequate protein diet and treated with the mTORC1 inhibitor rapamycin(4 mg/kg every other day)intraperitoneally,with the first two groups treated with vehicle as *** and pups were weighed daily,and feed intake was recorded every other *** production was measured every other day beginning on lactation day 4 by the weigh-suckle-weigh *** were collected after fasting and ***:Milk production and pup weight were similarly decreased by both protein restriction and rapamycin treatment,with final production at 50%of control(P=0.008)and final pup weight at 85%of control(P<0.001).Mammary phosphorylation of mTORC1’s downstream targets were decreased by protein restriction and rapamycin treatment(P<0.05),while very little effect was observed in the liver of rapamycin treated mice,and none by protein ***:Overall,sufficient supply of dietary amino acids was unable to maintain lactation performance status in mice with pharmacologically reduced mam

关键词： Amino acids Lactation Mammary Mouse model mTORC1 Rapamycin