检索结果-南通市图书馆

An Analysis of the Invariance and Conservation Laws of Some Classes of Nonlinear Ostrovsk. Equations and Related Systems

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2011年第1期28卷 1-4页

作者： k. Fak.ar A. h. k.ra Department of Mathematics Faculty of Science Universiti Teknologi Malaysia 81310 UTM Skudai Johor Malaysia School of Mathematics and Centre for Differential Equations Continuum Mechanics and Applications University of the Witwatersrand Johannesburg P Bag 3 Wits 2050 South Africa

A large class of partial differential equations in the modelling of ocean waves are due to Ostrovsk.. We determine the invariance properties （through the Lie point symmetry generators） and construct classes of conservation laws for some of the models. In the latter case, the method involves finding the ＇multipliers＇ associated with the conservation laws with a stronger emphasis on the ＇higher-order＇ ones. The relationship between the symmetries and conservation laws is investigated by considering the invariance properties of the multipliers.

关键词： Mathematical physics Statistical physics and nonlinear systems

Surface Acidity of Amorphous Aluminum hydroxide

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2006年第2期80卷 206-211页

作者： k. FUk.ShI k. TSUk.MURA h. YAMADA Research Center for Deep Geological Environments Ecomaterials Center

The surface acidity of synthetic amorphous AI hydroxide was determined by acid/base titration with several complementary methods including solution analyses of the reacted solutions and XRD characterization of the reacted solids. The synthetic specimen was characterized to be the amorphous material showing four broad peak. in XRD pattern. XRD analyses of reacted solids after the titration experiments showed that amorphous AI hydroxide rapidly transformed to crystalline bayerite at the alk.line condition （ph〉10）. The solution analyses after and during the titration k.p=^aAl^3＋/ah^＋^3 ,was 10^10.3. The amount of consumption of added acid or base during the titration experiment was attributed to both the protonation/deprotonation of dissolved AI species and surface hydroxyl group. The surface acidity constants, surface hydroxyl density and specific surface area were estimated by FITEQL 4.0.

关键词： amorphous AI hydroxide acid/base titration solubility crystallization surface acidity constants surface site density FITEQL

Continuous lobe reconnectionin the mid-tail and its relationship to substorms: Cluster observations of continuous lobe reconnection in the mid-magneto tail

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2005年第18期 91-97页

作者： A. k.rth,M. Frazen,h. Reme,k. h. glassmeier Max-Planck.Institute for Solar System Research Germany Max-Planck.Institute for Solar System Research Germany CNSR France IGM TU Braunschweig Germany

When the IMF turns southward, a great amount of magnetic energy is stored in the magnetotail, and the electric field across the magnetotail substantially en-hances. As long as magnetic reconnection (MR) in the mag-netotail initiates and continues, the magnetic field and plasma in the central plasma sheet are carried away to the near-Earth and down to the tail, the magnetic field and plasma in the lobe region enter the CPS and are involved in MR. We call this process “Continuous Lobe Reconnection (CLR)”. In this paper a detailed analysis of Cluster observa-tion of MR through 2001―2003 is made. Plenty of CLR events are found that led to considerable changes of tail con-figuration, appearance of BBF, as well as large-scale bubbles in which both plasma temperature and number density sub-stantially decrease. It is shown that in general CLR events last for dozens of minutes and have good correspondence to substorm initiation under the condition of continuous southward IMF.

关键词： lobe reconnection substorm bubble BBF.

Continuous lobe reconnectionin the mid-tail and its relationship to substorms:Cluster observations of continuous lobe reconnection in the mid-magneto tail

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2005年第18期50卷 2057-2063页

作者： CAO Xin PU Zuyin ZhANG hui FU Suiyan XIAO Chijie LIU Zhenxing J. B. cao A. k.rth M. Frazen Q. G. Zong h. Reme k. h. glassmeier School of Earth and Space Science Peking University Beijing 100871 China The National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China Center for Space Science and Applied Research Chinese Academy ofSciences Beijing 100080 China Max-Planck.Institute for Solar System Research Germany CSR Boston University US CNSR France IGM TU Braunschweig Germany

关键词：圆裂片重接亚暴磁能磁尾等离子体

NUMERICAL ANALYSIS OF ThE INFLUENCE OF ThE TIP CLEARANCE FLOWS ON ThE UNSTEADY CAVITATING FLOWS IN A ThREE- D IMENSIONAL INDUCER

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of hydrodynamics 2009年第1期21卷 34-40页

作者： Ok.TA k. UGAJIN h. MATSUMOTO Y. RIk.N Saitama 351-0198 Japan IhI Corporation Yokohama 235-8501 Japan Department of Mechanical Engineering The University of TokyoTokyo 113-8656 Japan

To clarify the influences of the tip clearance flows on the unsteady cavitating flow, the three-dimensional unsteady cavitating flows through both the two-dimensional cascades and the three-dimensional inducer with and without tip clearance are performed numerically. The governing equations for the compressible fluid flow with the DES turbulence model are employed with the assumption of the isentropic process of liquid phase. The evolution of cavities is represented as the source/sink.of vapor phase. The basic equations in the curve linear coordinate are solved by the finite difference method. As the results of the three-dimensional cavitating flows through the two-dimensional cascades, the tip clearance flows from the pressure side to the suction side of the blade produces the tip vortex cavitation, which affects the sheet cavitation on the leading edge of the next blade and enhances the block.ge effect near the casing than the flows without tip clearance. On the other hand, in the case of the three-dimensional inducer, the large back.low cavitation is observed around the inlet of the inducer, where the cavities are developed on the casing by the tip clearance flows. The large pressure gradient between the non-cavitating pressure side and the cavitating suction side enhances the tip clearance flows. The calculation considering the tip clearance reproduces the developed cavitation region similar to that of experimental visualizations. Additionally, the back.low cavitation rotates with the speed slower than the rotation speed of the inducer. Then, the rotation of back.low cavitation causes the periodic fluctuation of the outlet pressure greater than that of the inlet pressure.

关键词： cavitation inducer tip clearance flow numerical analysis

Parametric Study of an Underwater Finned Propulsor Inspired by Bluespotted Ray

在线全文

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2012年第2期9卷 166-176页

作者： Yonghua Zhang Jianhui he k. h. LOW Department of Mechatronics Engineering Taizhou Vocational ＆ Technical College Taizhou 318000 P. R. China School of Mechanical and Aerospace Engineering Nanyang Technological University Singapore 639798

The performance ofbluespotted rays was emulated in the design ofa bioinspired underwater propulsor in the present work. First, the movement of a live bluespotted ray was captured for the swimming mode and useful information to the biomimetic mechanism design. By virtue of the modular and reconfigurable design concept, an undulatory fin propulsion prototype was developed. With a proper experimental set-up, orthogonal experiments were conducted to investigate the effect of various fin design parameters on the propulsion speed, thrust, and power of the fish robot. The controllable fin parameters include frequency, amplitude, wavelength, fin shape, and undulatory mode. The significance of these parameters was also determined by using the variance analysis. The results demonstrate that the designed propulsor, imitating bluespotted rays with large expanded undulatory fins, is able to propel itself by changing various k.nematic parameters.

关键词： biomimetic underwater propulsor bluespotted ray undulatory fin fish robot parametric study

hOT WIRE MEASUREMENT OF TURBULENT BOUNDARY LAYER ON A FILM COOLING PLATE WITh DIFFUSION hOLES

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of hydrodynamics 2001年第2期13卷 15-23页

作者： Shi, h.h. k.riyama, k. Itoh, M. Dept. of Mechanics Zhejiang Univ. Hangzhou 310027 China

This study experimentally investigated the film cooling flowfield of a single row of diffusion holes, from which the secondary air flow was injected into a turbulent boundary layer with zero pressure gradient on a flat plate. Circular-shaped holes were also tested as a basis for comparison. All the holes were inclined downstream at 35° with respect to the surface and the lateral spacing between the holes was 3 diameters of the hole. The mainstream velocity was maintained at 17 m/s and the Reynolds number based on the injection hole diameter was almost 11000. The density ratio of the jet to mainstream was 1.0, and the jet-to-mainstream velocity ratios M were 0.5 and 1.5. Normal-type and X-type hot wire anemometries were used to measure the streamwise mean velocity and its components, the normal and shear turbulent Reynolds stress components at the locations from the back.ard edge of the injection hole to 25 diameters downstream.

关键词： Boundary layer flow Cooling Turbulent flow Vectors Velocity Wind tunnels

Development of an industrial Internet of things suite for smart factory towards re-industrialization

在线全文

学校读者我要写书评

暂无评论

Advances in Manufacturing 2017年第4期5卷 335-343页

作者： C. k. M. Lee S. Z. Zhang k. k. h. Ng Department of Industrial and Systems Engineering The Hong Kong Polytechnic University Hong Kong People's Republic of China Department of Information Management Zhejiang University of Finance and Economics Hangzhou 310018Zhejiang People's Republic of China

Re-industrialization, which supports industrial upgrading and transformation, promotes smart production and high value-added manufacturing processes, and helps to create new momentum for the economic. Under the current situation, industrialists encounter several chal- lenges to achieve re-industrialization. Firstly, the cost and technical thresholds for industrialists to leverage emerging technologies are high. Secondly, there are huge quantities and numerous types of Internet of things （IoT） devices in smart factories, warehouses and offices. The enormous extents of data exchange and communication, manage- ment, monitoring and control of IoT devices as well as the establishment and maintenance of a reliable cloud platform hinder industrialists to implement an integrated smart production management. Therefore, to achieve re-indus- trialization, an industrial Internet of things （IIoT） suite consisting of a micro-services-based IIoT cloud platform and IIoT-based smart hub is proposed, which helps to materialize re-industrialization and to conduct industrial upgrading and transformation to achieve smart production and high value-added manufacturing processes.

关键词： Industrial Intemet of things (IIoTs) Cloudplatform Micro-services-based Industry 4.0 Reindustrialization

The evolutionary development of plant-feeding insects and their nutritional endosymbionts

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Insect Science 2017年第6期24卷 910-928页

作者： Isabel h. Sk.dmore Allison k. hansen Department of Entomology University of Illinois Urbana-Champaign Ilfinois USA

herbivorous insects have evolved diverse mechanisms enabling them to feed on plants with suboptimal nutrient availability. Low nutrient availability negatively impacts insect herbivore development and fitness. To overcome this obstacle numerous insect lineages have evolved intimate associations with nutritional endosymbionts. This is especially true for insects that specialize on nitrogen-poor substrates, as these insects are highly dependent on intraceUular symbionts to provide nitrogen lack.ng in their insect host＇s diet. Emerging evidence in these systems suggest that the symbiont＇s and/or the insect＇s biosynthetic pathways are dynamically regulated throughout the insect＇s development to potentially cope with the insect＇s changing nutritional demands. In this review, we evaluate the evolutionary development of symbiotic insect cells （bacteriocytes） by comparing and contrasting genes and mechanisms involved in maintaining and regulating the nutritional symbiosis throughout insect development in a diversity of insect herbivore-endosymbiont associations. With new advances in genome sequencing and functional genomics, we eval- uate to what extent nutritional symbioses are shaped by （i） the regulation of symbiont titer, （ii） the regulation of insect symbiosis genes, and （iii） the regulation of symbiont genes. We discuss how important these mechanisms are for the biosynthesis of essential amino acids and vitamins across insect life stages in divergent insect-symbiont systems. We conclude by suggesting future directions of research to further elucidate the evolutionary development of bacteriocytes and the impact of these nutritional symbioses on insect plant interactions.

关键词： development evolutionary insect herbivores plant-insect microbe interactions symbiosis