检索结果-南通市图书馆

Acoustic Multi Emission Lens via Transformation Acoustics

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2018年第10期35卷 49-53页

作者： h.Barati z.Basiri A.Abdolali Applied Electromagnetic Laboratory School of Electrical Engineering Iran University of Science and Technology

Based on transformation acoustic methodology, we propose an algorithm for designing acoustic non-resonant lens antenna, which is competent to generate multiple directive beams that are pointing at the desired *** with previous works, the present approach is capable of adjusting the directivity of each radiated beam individually, which is of the utmost importance in several acoustic applications such as in sonar systems. A linear transformation function is intentionally used for eliminating the inhomogeneity of the obtained materials and to pave the way towards more general acoustic patterns. Several numerical simulations are performed to show the capability of the proposed method in manipulating the acoustic waves. To authenticate the concept,a structure that can generate four beams with different directivities is realized with non-resonant meta-fluid bi-layered structure through effective medium theory.

关键词： Acoustic Multi Emission Lens via Transformation Acoustics

A DESIGN FOR ENVIRONMENT METhODOLOGY FOR EVALUATION AND IMPROVEMENT OF DERIVATIVE CONSUMER ELECTRONIC PRODUCT DEVELOPMENT

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science and Systems Engineering 2011年第3期20卷 260-274页

作者： Tzu-An ChIANG z.h.ChE Tung-Te WANG Department of Business Administration National Taipei College of Business Department of Industrial Engineering & Management National Taipei University of Technology

Increasing environmental awareness and stringent environmental regulations have motivated many companies to incorporate ecodesign into product development. To assist companies to address the challenge, this research presents a design for environment （DfE） methodology to evaluate and improve derivative consumer electronic product development using a back-propagation neural network （BPNN） model and a technique for order preference by similarity to ideal solution （TOPSIS） method. Based on use of a BPNN, the life cycle assessment （LCA） models are developed to estimate quantities of hazardous chemical substances and energy consumption for a derivative consumer electronic product throughout the product life cycle. A performance evaluation and improvement model for DfE is then devised based on the TOPSIS method to analyze the ecodesign performance and provide concrete improvement strategies. With the aforementioned analysis of environmental performance, an enterprise can profoundly understand and significantly enhance the relative DfE performance of a new product compared to the similar competitive products. Finally, we apply an optical mouse development project as a case to elaborate and demonstrate the effectiveness of the proposed methodology. These analytical results can let us understand the DfE performance ranking and acquire the maximum reduced quantity of each DfE criterion for each module of a new product. Meanwhile, to enhance the green competitiveness of the new product, we recommend that the engineers should decrease the area of the circuit board of the new product. In addition, the material of the USB cable for the new product should be switched from the PVC material to the PE material.

关键词： Back-propagation neural network TOPSIS design for environment ecodesign product development

Electromagnetic effects on anisotropic expansion-free fluid content

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2023年第10期75卷 79-89页

作者： z Yousaf h Asad Bander Almutairi Adnan Malik Department of Mathematics University of the PunjabQuaid-i-Azam CampusLahore-54590Pakistan Department of Mathematics College of ScienceKing Saud UniversityP.O.Box 2455 Riyadh 11451Saudi Arabia School of Mathematical Sciences Zhejiang Normal UniversityJinhuaZhejiangChina

The major goal of this work is to find solutions of Einstein–Maxwell field equations for anisotropic,expansion-free,non-static,spherically distributed matter *** analytical models that highlight the major benefit of simplicity are shown and this makes it possible to use them as a toy model to illustrate how cavities ***,the transport equations,quasi-homologous constraints and the junction conditions are also evaluated along with their useful ***,the consequences of electric force on this system are summed up in the last section.

关键词： gravitation neutron stars modified gravity hydrodynamics voids

Energy transport for ion acoustic waves in a spin polarized quantum plasma

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2020年第1期72卷 124-129页

作者： M Ayub z Iqbal h A Shah G Murtaza Salam Chair Department of PhysicsG.C.UniversityKatchery RoadLahore 54000Pakistan Department of Physics G.C.UniversityKatchery RoadLahore 54000Pakistan Department of Physics Mirpur University of Science and TechnologyMirpur-10250(AJK)Pakistan

The separate spin evolution quantum hydrodynamics(SSE-QhD)model is used to investigate the energy behavior for ion acoustic waves in degenerate quantum *** results show that the energy flow speed decreases with spin polarization *** is also shown that it decreases with the increasing rate up to a certain range of wave number and then it goes to zero *** is observed that Bohm potential suppresses the energy flow *** is also noticed that the energy flow speed deviates from the group velocity even in the absence of Bohm potential ***,the contribution of of Bohm poential effect in spin polarized plasma reduces the extent of deviation.

关键词： spin polarization quantum plasma ion acoustic wave energy flow speed

FINITE ELEMENT ANALYSIS FOR MICROSTRUCTURE EVOLUTION IN hOT FINIShING ROLLING OF STEEL STRIPS

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2007年第2期20卷 79-86页

作者： z.D. Qu S.h. zhang D.z. Li z.T. Wang Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China College of Material Science and Engineering Taiyuan University of Science andTechnology Taiyuan 030024 China Shenyang Ligong University Shenyang 110168 China

A computer model that describes the evolution of microstructures during the hot finishing rolling of SS400 steel has been proposed. It has been found that the microstructure strongly depends on processing of materials and on their parameters, which affected the history of the thermomechanical variables, such as temperature, strain, and strain rate. To investigate the microstructural evolutions during the hot finishing rolling process, the rigid-thermoviscoplastic finite element method （FEM） has been combined with dynamic recrystallization, static recrystallization, and grain growth models. The simulation results show a good agreement with those from the prediction software online.

关键词： finite element method (FEM) finishing rolling microstructure evolution recrystallization

An efficient method for computing excess free energy of liquid

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2018年第1期61卷 135-140页

作者： Jianing Song Linqiong Qiu John z.h. zhang School of Chemistry and Molecular Engineering East China Normal University Shanghai 200062 China NYU-ECNU Center for Computational Chemistry at NYU ShanghaL Shanghai 200062 China State Key Laboratory of Precision Spectroscopy East China Normal University Shanghai 200062 China Department of Chemistry New York University NY NY 10003 USA

We present a new theoretical method for efficient calculation of free energy of liquid. This interaction entropy method allows one to compute entropy and free energy of liquid from standard single step MD(molecular dynamics) simulation directly in liquid state without the need to perform MD simulations at many intermediate states as required in thermodynamic integration or free energy perturbation methods. In this new approach, one only needs to evaluate the interaction energy of a single(fixed) liquid molecule with the rest of liquid molecules as a function of time from a standard MD simulation of liquid and the fluctuation of distribution of this interaction energy is then used to calculate the interaction entropy of the liquid. Explicit theoretical derivation of this interaction entropy approach is provided and numerical calculations for the benchmark liquid water system were carried out using three different water models. Numerical analysis of the result was performed and comparison of the computational result with experimental data and other theoretical results were provided. Excellent agreement of calculated free energies with the experimental data using TIP4 P model is obtained for liquid water.

关键词： excess free energy liquid MD simulation interaction entropy

Strong invariance principle for a counterbalanced random walk

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics(A Journal of Chinese Universities) 2024年第2期39卷 370-380页

作者： TAN hui-qun hU zhi-shui DONG Liang International Institute of Finance School of ManagementUniversity of Science and Technology of ChinaHefei 230026China Center for Basic Teaching and Experiment Nanjing University of Science and TechnologyJiangyin 214443China

We study a counterbalanced random walkS_(n)=X_(1)+…+X_(n),which is a discrete time non-Markovian process andX_(n) are given recursively as *** n≥2,X_(n) is a new independent sample from some fixed law̸=0 with a fixed probability p,andX_(n)=−X_(v(n))with probability 1−p,where v(n)is a uniform random variable on{1;…;n−1}.We apply martingale method to obtain a strong invariance principle forS_(n).

关键词： random walk martingale invariance principle

VOLUMETRIC MASS TRANSFER COEFFICIENT BETWEEN SLAG AND METAL IN COMBINED BLOWING CONVERTER

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2005年第2期18卷 91-95页

作者： z.h.Wu z.S.zou W.Wu SchoolofMaterialsandMetallurgy NortheasternUniversityShenyang110004China CentralIron＆SteelResearchInstitute Beijing100081China

The effects of operation parameters of combined blowing converter on the volumetric mass transfer coefficient between slag and steel are studied with a cold model with water simulating steel, oil simulating slag and benzoic acid as the transferred substance between water and oil. The results show that, with lance level of 2.1m and the top blowing rate of 25000Nm3/h, the volumetric mass transfer coefficient changes most significantly when the bottom blowing rate ranges from 384 to 540Nm3/h. The volumetric mass transfer coefficient reaches its maximum when the lance level is 2.1m, the top blowing rates is 30000Nm3/h, and the bottom blowing rate is 384Nm3/h with tuyeres located symmetrically at 0.66D of the converter bottom.

关键词： combined blowing converter cold modeling volumetric mass transfer coefficient operational parameter

hydrodynamic pressure on concrete face rockfill dams subjected to earthquakes

在线全文

学校读者我要写书评

暂无评论

Journal of hydrodynamics 2019年第1期31卷 152-168页

作者： zhong-zhi Fu Sheng-shui Chen Guo-ying Li Geotechnical Engineering Department Nanjing Hydraulic Research InstituteNanjing 210024China Key Laboratory of Failure Mechanism and Safety Control Techniques of Earth-Rock Dams Ministry of Water ResourceNanjing 210029China

The hydrodynamic pressure is an important load on concrete face rockfill dams (CFRDs) subjected to earthquakes,the influence of which,however,is not clear as compared with that in concrete *** this paper,the coupling effect between the CFRDs and the reservoir water is studied based on two-dimensional finite element simulations by using a verified *** is found that neglecting the solid-fluid coupling effect not only results in an overestimation of the acceleration response within the rockfill materials but also makes an overestimation of the dynamical stresses in the concrete *** a reliable seismic response analysis of the CFRDs,therefore,the hydrodynamic pressure should be taken into account,particularly when the dam is subjected to a simultaneous excitation in both horizontal and vertical *** results show,however,that the compressibility of the water can be safely neglected in the seismic response analyses of the CFRDs even when the dam is as high as 300 m,except when the excitation is quite abundant in high frequency contents.

关键词： Concrete face rockfill dam hydrodynamic pressure seismic response earthquake