检索结果-南通市图书馆

Science China(Technological Sciences) 2009年第11期52卷 3335-3347页

作者： KRONVANG Brian windolf jфrgen GRANT Ruth ANDERSEN Hans E THODSEN Hans OVESEN Niels B LARSEN SФren E National Environmental Research Institute Aarhus University VejlsФvej 25 DK-8600 Silkeborg Denmark

Nationwide monitoring of the aquatic environment was initiated in 1988 in Denmark as a means to follow the outcome of the Action Plans for nutrient pollution of the aquatic environment. Five Action Plans have been adopted by the Danish Parliament since 1985 and the nationwide monitoring programme can be used to quantify the outcome as shown by reductions in nutrient discharges from both point and non-point sources. Moreover, the empirical experience gathered from nearly 20 years of monitoring is assisting the development and calibration of models for simulation of nitrogen leaching, nitrogen removal in groundwater and surface waters and the establishment of a P-index all covering the entire land area of Denmark.

关键词： nitrogen phosphorus monitoring data point sources non-point sources models Action Plans Danish experience

Signatures of non-Euclidean metrics in the optical features of microcavities

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2025年第04期Mechanics & Astronomy) .卷 269-270页

作者： Hans-jürgen St?ckmann Fachbereich Physik der Universit?t Marburg

Starting with the nineties of the last century disc-shaped dielectric cavities have received a lot of attention because of their interest in the design of micro-lasers and integrated optics applications [1-5]. The light can be trapped inside the dielectric cavity by total internal reflection, or can partly escape by refraction, depending on the angle of incidence with respect to the boundary.

关键词：

同方期刊数据库

Microstructural evolution during tempering process and mechanical properties of Cr-Ni-Mo-V/Nb high strength steel

在线全文

学校读者我要写书评

暂无评论

journal of Iron and Steel Research International 2025年第1期32卷 270-281页

作者： Zi-wei Lv jing Fan Rui Wang Zhi-qiang Yu Yan Kang Yong Hu Lei-feng Tuo jürgen Eckert Zhi-jie Yan School of Materials Science and Engineering North University of ChinaTaiyuan 030051ShanxiChina Shanxi Key Laboratory of Advanced Metal Materials for Special Environments North University of ChinaTaiyuan 030051ShanxiChina School of Materials Science and Engineering Taiyuan University of Science and TechnologyTaiyuan 030024ShanxiChina Erich Schmid Institute of Materials Science Austrian Academy of SciencesLeoben 8700Austria Department of Materials Science Chair of Materials PhysicsMontanuniversitat LeobenLeoben 8700Austria

High strength steels exhibit superior mechanical properties due to the unique microstructure,which successfully solves the drawback of the inevitable strength-toughness trade-off that occurs in traditional *** we investigated the effect of matrix and precipitates on mechanical properties of Cr-Ni-Mo-V/Nb steel after water quenching and tempering(150-500℃).The results showed that the microstructure of the present steel is noticeably tuned by changing the tempering *** excellent combination of strength(a yield strength of 1308 MPa with a total elongation of 8.2%)and toughness(Charpy V-notch impact toughness of 40.5 j/cm^(2))is obtained upon tempering at 200℃.This is attributed to the lath martensite containing high dislocation density,the martensite-twin substructure,and the strengthening effects of the precipitated needle-likeε-carbides and spherical VC *** acicularε-carbides are replaced by the rod-shaped Fe_(3)C at the tempering temperature of 350℃,resulting in the remarkable deterioration in strength,hardness,and *** carbides formed at a tempering temperature of 500℃ are beneficial to the enhancement of the elongation and toughness,but the strength decreases due to the matrix softening caused by the recovery of dislocation.

关键词： High strength steel Tempering Microstructure Carbide Mechanical property

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

经济地生产电动汽车

现代制造 2025年第02期 26-27页

作者： jürgen Fürst

磨削良好的大前角可转位刀片适合于在特种加工中使用,也适合于加工特种材料。在切削加工那些不稳定的工件时和在切削散热性能很差的坚硬材料时,这种可转位刀片都有着上佳表现。德国施瓦本地区的Karl Heinz Arnod有限公司30多年来就一直...

磨削良好的大前角可转位刀片适合于在特种加工中使用,也适合于加工特种材料。在切削加工那些不稳定的工件时和在切削散热性能很差的坚硬材料时,这种可转位刀片都有着上佳表现。德国施瓦本地区的Karl Heinz Arnod有限公司30多年来就一直致力于将自己研发制造的可转位刀片技术推向顶峰。它们研发生产的Arno系列大前角可转位刀片为全球众多的机械加工企业提供了大量的选择可能性。今天,聪明的刀具客户已经在电动汽车零部件的生产过程中采用了更加经济、更加有利于企业健康发展的切削加工技术,减少了费用开支。

关键词：

Supervision of two fundamental problems in modern fluid dynamics for sparing energy

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

journal of Thermal Science 2009年第2期18卷 97-98页

作者： jürgen Zierep Institut für Strmungslehre Universitt Karlsruhe

The normal shock at a curved surface in transonic flow leads to a superdetermined boundary value problem. A bump behind the shock decreases the drag of the airfoil and reduces the necessary energy. Flows of non-Newtonian media lead in the contrary to subdetermined boundary initial problems. The energy balance for these fluids is of great interest for chemical engineering.

关键词： Transonic flow Shock at a curved wall Superdetermined problem Non- Newtonian media Subdeermined problem Energy balance.

Dust growth in protoplanetary disks-a comprehensive experimental / theoretical approach

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2010年第12期10卷 1199-1214页

作者： jürgen Blum Institut für Geophysik und extraterrestrische Physik University of Braunschweig

More than a decade of dedicated experimental work on the collisional physics of protoplanetary dust has brought us to a point at which the growth of dust aggregates can - for the first time - be self-consistently and reliably modeled. In this article, the emergent collision model for protoplanetery dust aggregates, as well as the numerical model for the evolution of dust aggregates in protoplanetary disks, is reviewed. It turns out that, after a brief period of rapid collisional growth of fluffy dust aggregates to sizes of a few centimeters, the protoplanetary dust particles are subject to bouncing collisions, in which their porosity is considerably decreased. The model results also show that low-velocity fragmentation can reduce the final mass of the dust aggregates but that it does not trigger a new growth mode as discussed previously. According to the current stage of our model, the direct formation of kilometer-sized planetesimals by collisional sticking seems unlikely, implying that collective effects, such as the streaming instability and the gravitational instability in dust-enhanced regions of the protoplanetary disk, are the best candidates for the processes leading to planetesimals.

关键词： planetary systems: protoplanetary disks -- planetary systems: formation-- methods: laboratory -- methods: numerical

Apples to oranges:environmentally derived,dynamic regulation of serotonin neuron subpopulations in adulthood?

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2025年第9期20卷 2596-2597页

作者： Christopher j.O’Connell Matthew j.Robson Department of Genetics College of MedicineHarvard UniversityBostonMAUSA james L.Winkle College of Pharmacy Division of Pharmaceutical SciencesUniversity of CincinnatiCincinnatiOHUSA Neuroscience Graduate Program College of MedicineUniversity of CincinnatiCincinnatiOHUSA

Traumatic brain injury(TBI)is a public health problem with an undue economic burden that impacts nearly every age,ethnic,and gender group across the globe(Capizzi et al.,2020).TBIs are often sustained during a dynamic range of exposures to energetic environmental forces and as such outcomes are typically heterogeneous regarding severity and pathology(Capizzi et al.,2020).

关键词： sustained orange dynamic

Exaptation at the molecular genetic level

在线全文

学校读者我要写书评

暂无评论

Science China(Life Sciences) 2019年第4期62卷 437-452页

作者： jürgen Brosius Institute of Experimental Pathology (ZMBE) Centre for Molecular Biology of Inflammation University of Münster Brandenburg Medical School (MHB)

The realization that body parts of animals and plants can be recruited or coopted for novel functions dates back to, or even predates the observations of Darwin. S.j. Gould and E.S. Vrba recognized a mode of evolution of characters that differs from adaptation. The umbrella term aptation was supplemented with the concept of exaptation. Unlike adaptations, which are restricted to features built by selection for their current role, exaptations are features that currently enhance fitness, even though their present role was not a result of natural selection. Exaptations can also arise from nonaptations; these are characters which had previously been evolving neutrally. All nonaptations are potential exaptations. The concept of exaptation was expanded to the molecular genetic level which aided greatly in understanding the enormous potential of neutrally evolving repetitive DNA—including transposed elements, formerly considered junk DNA—for the evolution of genes and genomes. The distinction between adaptations and exaptations is outlined in this review and examples are given. Also elaborated on is the fact that such distinctions are sometimes more difficult to determine; this is a widespread phenomenon in biology, where continua abound and clear borders between states and definitions are rare.

关键词： exaptation adaptation aptation neofunctionalization subfunctionalization non-protein coding RNA cooptation recruitment novel functional gene modules de novo genes retrogenes

Taguchi Analysis for Improving Optimization of Integrated Forward/Reverse Logistics

在线全文

学校读者我要写书评

暂无评论

journal of the Operations Research Society of China 2023年第3期11卷 529-552页

作者： Elham Behmanesh jürgen Pannek International Graduate School for Dynamics in Logistics University of BremenBremenGermany Faculty of Production Engineering University of BremenBremenGermany BIBA Bremer Institut für Produktion und Logistik GmbH BremenGermany

The distribution–allocation problem is known as one of the most comprehensive strategic *** real-world cases,it is impossible to solve a distribution–allocation problem completely in acceptable *** forces the researchers to develop efficient heuristic techniques for the large-term operation of the whole supply *** techniques provide near optimal solution and are comparably fast particularly for large-scale test *** paper presents an integrated supply chain model which is flexible in the delivery *** solution methodology,we apply a memetic algorithm with a novelty in population *** identify the optimum operating condition of the proposed memetic algorithm,Taguchi method is *** this study,four factors,namely population size,crossover rate,local search iteration and number of iteration,are *** the best level of the considered parameters is the outlook of this research.

关键词： Integrated logistics network Flexible path Memetic algorithm Taguchi analysis

Multi-Product Expansion with Suzuki’s Method: Generalization

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Numerical Mathematics(Theory,Methods and Applications) 2011年第1期4卷 68-91页

作者： jürgen Geiser Department of Mathematics Humboldt University of BerlinUnter den Linden 6D-10099 BerlinGermany

In this paper we discuss the extension to exponential splitting methods withrespect to time-dependent operators. We concentrate on the Suzuki’s method, whichincorporates ideas to the time-ordered exponential of [3, 11, 12, 34]. We formulate themethods with respect to higher order by using kernels for an extrapolation scheme. Theadvantages include more accurate and less computational intensive schemes to specialtime-dependent harmonic oscillator problems. The benefits of the higher order kernelsare given on different numerical examples.

关键词： Suzuki’s method multiproduct expansion multiplicate and additive splitting schemes exponential splitting