期刊文献+
共找到457篇文章
< 1 2 23 >
每页显示 20 50 100
A Hybrid Dung Beetle Optimization Algorithm with Simulated Annealing for the Numerical Modeling of Asymmetric Wave Equations
1
作者 Wei Xu-ruo Bai Wen-lei +2 位作者 Liu Lu Li You-ming Wang Zhi-yang 《Applied Geophysics》 SCIE CSCD 2024年第3期513-527,618,共16页
In the generalized continuum mechanics(GCM)theory framework,asymmetric wave equations encompass the characteristic scale parameters of the medium,accounting for microstructure interactions.This study integrates two th... In the generalized continuum mechanics(GCM)theory framework,asymmetric wave equations encompass the characteristic scale parameters of the medium,accounting for microstructure interactions.This study integrates two theoretical branches of the GCM,the modified couple stress theory(M-CST)and the one-parameter second-strain-gradient theory,to form a novel asymmetric wave equation in a unified framework.Numerical modeling of the asymmetric wave equation in a unified framework accurately describes subsurface structures with vital implications for subsequent seismic wave inversion and imaging endeavors.However,employing finite-difference(FD)methods for numerical modeling may introduce numerical dispersion,adversely affecting the accuracy of numerical modeling.The design of an optimal FD operator is crucial for enhancing the accuracy of numerical modeling and emphasizing the scale effects.Therefore,this study devises a hybrid scheme called the dung beetle optimization(DBO)algorithm with a simulated annealing(SA)algorithm,denoted as the SA-based hybrid DBO(SDBO)algorithm.An FD operator optimization method under the SDBO algorithm was developed and applied to the numerical modeling of asymmetric wave equations in a unified framework.Integrating the DBO and SA algorithms mitigates the risk of convergence to a local extreme.The numerical dispersion outcomes underscore that the proposed SDBO algorithm yields FD operators with precision errors constrained to 0.5‱while encompassing a broader spectrum coverage.This result confirms the efficacy of the SDBO algorithm.Ultimately,the numerical modeling results demonstrate that the new FD method based on the SDBO algorithm effectively suppresses numerical dispersion and enhances the accuracy of elastic wave numerical modeling,thereby accentuating scale effects.This result is significant for extracting wavefield perturbations induced by complex microstructures in the medium and the analysis of scale effects. 展开更多
关键词 FINITE-DIFFERENCE Asymmetric wave equation Numerical modeling DBO algorithm SA algorithm
下载PDF
碎石桩平台在海岸工程的应用
2
作者 华晓涛 王建平 杨秀礼 《港工技术》 2018年第2期51-54,共4页
针对碎石桩施工在海上的局限性,本文提出一种新型碎石桩施工平台,大幅度增加了施工窗口期,提高了施工效率,并经在以色列阿什杜德港码头工程成功应用,实践证明该研究成功可靠。
关键词 近海工 碎石桩平台 装备研究 行车起重机 阿什杜德港 港口 港口工
下载PDF
绵羊盲肠和结肠综合肌电的活动规律 被引量:2
3
作者 程勇 贾斌 +1 位作者 姜萍 石玉珂 《新疆农业大学学报》 CAS 1998年第2期155-159,共5页
盲肠和结肠初袢的电活动,均为短周期移行性综合肌电。起自盲肠尖的大量峰电,可移行止于结肠初袢远端;而起自结肠初袢远端较多的峰电,能直接移向盲肠尖;起步于盲肠基的峰电能发生两向移行。结肠旋袢和终袢的电活动,均为自发地短周... 盲肠和结肠初袢的电活动,均为短周期移行性综合肌电。起自盲肠尖的大量峰电,可移行止于结肠初袢远端;而起自结肠初袢远端较多的峰电,能直接移向盲肠尖;起步于盲肠基的峰电能发生两向移行。结肠旋袢和终袢的电活动,均为自发地短周期综合肌电;并以旋袢的周期为最短。此外结肠终袢还产生大振幅(170.54μV)、长间歇(35.94min)、持续性(5.39min)峰电活动。 展开更多
关键词 综合肌电 对程 峰电 移行 绵羊 盲肠 结肠
下载PDF
Development of a distributed and integratable manufacturing execution system framework 被引量:4
4
作者 杨浩 周娜 +1 位作者 朱剑英 罗翔 《Journal of Southeast University(English Edition)》 EI CAS 2003年第1期64-69,共6页
Using remote method invocation (RMI) and a distributed object-oriented technique, this paper presents a systematic approach to developing a manufacturing execution system (MES) framework, which is open, modularized, d... Using remote method invocation (RMI) and a distributed object-oriented technique, this paper presents a systematic approach to developing a manufacturing execution system (MES) framework, which is open, modularized, distributed, configurable, interoperable and maintainable. Moreover, the design patterns for the framework .are developed and a variety of functional components are designed by inheriting appropriate patterns. And then an application is constructed by invoking corresponding methods of related components. An MES system implementing the framework and design patterns can be facilely integrated with other manufacturing applications, such as enterprise resource planning (ERP) and floor control system (FCS) . 展开更多
关键词 manufacturing execution system framework design pattern distributed object-oriented remote method invocation
下载PDF
SYMMETRIC POSITIVE DEFINITE SOLUTIONS OF MATRIX EQUATIONS (AX,XB)=(C,D) AND AXB=C 被引量:1
5
作者 戴华 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 1996年第2期56+52-55,共5页
The symmetric positive definite solutions of matrix equations (AX,XB)=(C,D) and AXB=C are considered in this paper. Necessary and sufficient conditions for the matrix equations to have symmetric positive de... The symmetric positive definite solutions of matrix equations (AX,XB)=(C,D) and AXB=C are considered in this paper. Necessary and sufficient conditions for the matrix equations to have symmetric positive definite solutions are derived using the singular value and the generalized singular value decompositions. The expressions for the general symmetric positive definite solutions are given when certain conditions hold. 展开更多
关键词 numerical algebra MATRIX EQUATION symmetric positive definite solution
下载PDF
The Design and Implementation of an Object-Oriented Hypermedia System
6
作者 曹元大 马锐 《Journal of Beijing Institute of Technology》 EI CAS 1997年第1期78-84,共7页
Presents an object-oriented NBO(node-block-object)data model for hypermedia system.It takes advantage of object-oriented method,encapsulates all multimedia information as well as link functions in one unit,It has succ... Presents an object-oriented NBO(node-block-object)data model for hypermedia system.It takes advantage of object-oriented method,encapsulates all multimedia information as well as link functions in one unit,It has successfully achieved cross link to offer much better flexibility and two-way link to realize forward and backward searching in hypermedia system navigation.A conditional relation on links has also been realized,that is very helpful for time sensitive multimedia information processing and multimedia object cooperation. 展开更多
关键词 MULTIMEDIA HYPERMEDIA LINK object-oriented programming
下载PDF
Form Invariance of Routh Equations
7
作者 王树勇 梅凤翔 《Journal of Beijing Institute of Technology》 EI CAS 2002年第3期329-331,共3页
The form invariance of Routh equations in holonomic systems is studied. The definition and criterion for the form invariance under the infinitesimal transformations are given. The relation of the form invariance with ... The form invariance of Routh equations in holonomic systems is studied. The definition and criterion for the form invariance under the infinitesimal transformations are given. The relation of the form invariance with the Noether symmetry and the Lie symmetry is discussed. 展开更多
关键词 analytical mechanics form invariance Noether symmetry Lie symmetry
下载PDF
Synthesis and Surface Activity of Heterogemini Imidazolium Surfactants
8
作者 赵晓辉 叶志文 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2016年第2期249-254,I0002,共7页
A series of heterogemini imidazolium surfactants with two-methylene spacer groups ([Cm- 2-Cnim]Br2, m, n=8, 10, 12, 14, 16; m≠n) have been synthesized and characterized by 1H NMR and ESI-MS spectroscopy. The effect... A series of heterogemini imidazolium surfactants with two-methylene spacer groups ([Cm- 2-Cnim]Br2, m, n=8, 10, 12, 14, 16; m≠n) have been synthesized and characterized by 1H NMR and ESI-MS spectroscopy. The effects of various reaction parameters, including stoichiometry, reaction temperature and time, were investigated. In addition, the surface activity study about heterogemini imidazolium surfactants was carried out and the influences of dissymmetric degree on the surface properties were also discussed. 展开更多
关键词 Heterogemini imidazolium surfactants SYNTHESIS Optimal conditions Surfaceactivity Dissymmetric degree
下载PDF
Visual object-oriented application for lane following on intelligent highway system
9
作者 王春燕 王炜 +1 位作者 陆建 常玉林 《Journal of Southeast University(English Edition)》 EI CAS 2003年第2期165-167,共3页
A visual object-oriented software for lane following on intelligent highway system (IHS) is proposed. According to object-oriented theory, 3 typical user services of self-check, transfer of human driving and automatic... A visual object-oriented software for lane following on intelligent highway system (IHS) is proposed. According to object-oriented theory, 3 typical user services of self-check, transfer of human driving and automatic running and abnormal information input from the sensors are chosen out. In addition, the functions of real-time display, information exchanging interface, determination and operation interweaving in the 3 user services are separated into 5 object-oriented classes. Moreover, the 5 classes are organized in the visual development environment. At last, experimental result proves the validity and reliability of the control application. 展开更多
关键词 intelligent transportation system intelligent highway system lane following visual object-oriented application
下载PDF
Conserved quantities from Lie symmetries for nonholonomic systems 被引量:2
10
作者 张毅 薛纭 《Journal of Southeast University(English Edition)》 EI CAS 2003年第3期289-292,共4页
This paper presents a new method to seek the conserved quantity from a Lie symmetry without using either Lagrangians or Hamiltonians for nonholonomic systems. The differential equations of motion of the systems are es... This paper presents a new method to seek the conserved quantity from a Lie symmetry without using either Lagrangians or Hamiltonians for nonholonomic systems. The differential equations of motion of the systems are established. The definition of the Lie symmetrical transformations of the systems is given, which only depends upon the infinitesimal transformations of groups for the generalized coordinates. The conserved quantity is directly constructed in terms of the Lie symmetry of the systems. The condition under which the Lie symmetry can lead to the conserved quantity and the form of the conserved quantity are obtained. Finally, an example is given to illustrate the application of the result. 展开更多
关键词 analytical mechanics nonholonomic system SYMMETRY conserved quantity
下载PDF
Optimization of Chromatographic Conditions for Detecting Ellagic Acid in Pomegranate Peels Using HPLC Method 被引量:3
11
作者 夏小龙 彭蓉 +3 位作者 李树垠 李端阳 干霞 白琦 《Agricultural Science & Technology》 CAS 2012年第11期2400-2403,共4页
[Objective] This study aimed to optimize the chromatographic conditions for detecting ellagic acid in pomegranate peels using HPLC method. [Method] By using 0.2 mg/ml ellagic acid standard solution, on the basis of si... [Objective] This study aimed to optimize the chromatographic conditions for detecting ellagic acid in pomegranate peels using HPLC method. [Method] By using 0.2 mg/ml ellagic acid standard solution, on the basis of single-factor experiment and orthogonal experiment, chromatographic conditions (mobile phase ratio, flow rate, col- umn temperature) for detecting ellagic acid using HPLC were optimized. Based on the optimal chromatographic conditions, the ellagic acid content in experimental pomegranate peels was determined. [Resull] The optimal chromatographic conditions for detecting ellagic acid in pomegranate peels using HPLC method are: 1.2% phos- phoric acid:acetonitrile=85:15, column temperature of 35 ℃, and flow rate of 1.0 ml/min. The linear regression equation of ellagic acid is: y=2.9e+0.6x+4.4e+5 (FF=9 999). Ac- cording to the standard addition recovery test, the average recovery rate of ellagic acid is 98.20%, and RSD is 0.60%. Under above optimized chromatographic condi- tions, ellagic acid can be well separated from other interfering components in pomegranate peels, with shorter peak time and ideal effect, which is convenient for the detection in production practices. [Conclusion] This study laid the foundation for detecting ellagic acid in pomegranate peels using HPLC method. 展开更多
关键词 Pomegranate peel Etlagic acid DETECTION HPLC
下载PDF
NEW REMOTE USER AUTHENTICATION SCHEME USING SMART CARD 被引量:2
12
作者 杨君佐 王永建 周渊 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2012年第2期187-192,共6页
Because the modified remote user authentication scheme proposed by Shen, Lin and Hwang is insecure, the Shen-Lin-Hwang' s scheme is improved and a new secure remote user authentication scheme based on the bi- linear ... Because the modified remote user authentication scheme proposed by Shen, Lin and Hwang is insecure, the Shen-Lin-Hwang' s scheme is improved and a new secure remote user authentication scheme based on the bi- linear parings is proposed. Moreover, the effectiveness of the new scheme is analyzed, and it is proved that the new scheme can prevent from all kinds of known attack. The one-way hash function is effective in the new scheme. The new scheme is proved that it has high effectiveness and fast convergence speed. Moreover, the ap- plication of the new scheme is easy and operational. 展开更多
关键词 remote user authentication password authentication remote login bilinear pairings
下载PDF
Multi-solution of Semilinear Elliptic Equation on R^N
13
作者 冯秀芳 郑驻军 +1 位作者 赵秀娥 郑君英 《Chinese Quarterly Journal of Mathematics》 CSCD 2001年第2期98-103,共6页
In this paper, we give a Z 2 index theory of generalized critical point. By this theory we get a sufficient condition on the existing result of a class functional, as an example we give a new result that the equa... In this paper, we give a Z 2 index theory of generalized critical point. By this theory we get a sufficient condition on the existing result of a class functional, as an example we give a new result that the equation-Δu+u=|u| p-1 u, x∈R N,(1)has infinite solutions. 展开更多
关键词 generalized critical point Z 2 index semilinear equation
下载PDF
Initial Alignment Technique for SINS of Vehicles in the Moving State 被引量:17
14
作者 缪玲娟 沈军 +1 位作者 刘伟 杨勇 《Journal of Beijing Institute of Technology》 EI CAS 2002年第3期234-239,共6页
An initial alignment technique for the strapdown inertial navigation system (SINS) of vehicles in the moving state is researched. By selecting an odometer as the system’s external sensor, the mathematical model for t... An initial alignment technique for the strapdown inertial navigation system (SINS) of vehicles in the moving state is researched. By selecting an odometer as the system’s external sensor, the mathematical model for the alignment in the moving state is established and the observability of the system is analyzed. The results show that the SINS can successfully achieve the precision alignment in 10 min when the vehicle is moving toward the prearranged place after its staying for several seconds to perform the coarse alignment. The precision of alignment can also be improved in the moving state compared with that in the static state. 展开更多
关键词 strapdown inertial navigation system initial alignment Kalman filter
下载PDF
论信贷配给对宏观经济波动的影响
15
作者 何杉 《现代商业》 2019年第3期105-106,共2页
纵观世界历史,银行业自出现以来都是在整个社会当中具有重要影响力的行业之一。尤其是在当代的社会,银行业的作用与影响力更加无与伦比,但宏观经济的波动与资本逐利的天性将有可能导致商业银行会发生较为严重的信贷配给行为,继而导致融... 纵观世界历史,银行业自出现以来都是在整个社会当中具有重要影响力的行业之一。尤其是在当代的社会,银行业的作用与影响力更加无与伦比,但宏观经济的波动与资本逐利的天性将有可能导致商业银行会发生较为严重的信贷配给行为,继而导致融资企业的信贷可得性下降。在这样的影响之下,反而会对宏观经济的衰退产生较为显著的抑制影响。因此,我国政府向来极为重视信贷配给对宏观经济的影响,并出台相关政策以保障信贷配给对宏观经济波动产生正面的影响。 展开更多
关键词 信贷配给 对程信息 宏观经济波动 信贷可得性
下载PDF
O-O Analysis of Vehicle Body Design and Establishment of Engineering Database
16
作者 陈思忠 林磊明 +1 位作者 张斌 谷中丽 《Journal of Beijing Institute of Technology》 EI CAS 1998年第2期184-189,共6页
To establish the object-oriented (O-O) engineering for vehicle body design Methods characteristics of vehicle body design data were analyzed by means of theO-Omethod The analytical results were transformed intothe eng... To establish the object-oriented (O-O) engineering for vehicle body design Methods characteristics of vehicle body design data were analyzed by means of theO-Omethod The analytical results were transformed intothe engineering databasethat canbeusedsufficiently to describe the relative information of vehicle body design data.Results TheO-Oengineeringdatabaseforvehiclebodydesignis realized and practiced in the process ofbody design for a QCJ7082 economical car. Conclusion The method is successful in trans- forming vehicle body design object into engineering database.The database supports each procedure of vehicle body design perfectly 展开更多
关键词 vehicle body design engineering database OBJECT-ORIENTED
下载PDF
N-S EQUATION CALCULATIONS ON MULTI-ELEMENT AIRFOILS WITH ZONAL PATCHED GRIDS 被引量:2
17
作者 郭同庆 陆志良 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2003年第2期155-158,共4页
For a complex flow about multi-element airfoils a mixed grid method is set up. C-type grids are produced on each element′s body and in their wakes at first, O-type grids are given in the outmost area, and H-type grid... For a complex flow about multi-element airfoils a mixed grid method is set up. C-type grids are produced on each element′s body and in their wakes at first, O-type grids are given in the outmost area, and H-type grids are used in middle additional areas. An algebra method is used to produce the initial grids in each area. And the girds are optimized by elliptical differential equation method. Then C-O-H zonal patched grids around multi-element airfoils are produced automatically and efficiently. A time accurate finite-volume integration method is used to solve the compressible laminar and turbulent Navier-Stokes (N-S) equations on the grids. Computational results prove the method to be effective. 展开更多
关键词 multi-element airfoils zonal patched grids finite-volume method N-S equations
下载PDF
Existence of Many and Infinitely Many Periodic Solutions for Some Types of Differential Delay Equations
18
作者 葛渭高 《Journal of Beijing Institute of Technology》 EI CAS 1993年第1期5-14,共10页
J.Kaplan and J.Yorke's method is extended to establish the exis- tence of many and infinitely many periodic solutions for the DDEs (t) =±f(x(t-1))±f(x(t-2))and (t)=±f(x(t-1).
关键词 difference differential equation periodic solution SYMMETRY
下载PDF
Shrek:a dynamic object-oriented programming language 被引量:1
19
作者 曹璟 徐宝文 周毓明 《Journal of Southeast University(English Edition)》 EI CAS 2009年第1期31-35,共5页
From a perspective of theoretical study, there are some faults in the models of the existing object-oriented programming languages. For example, C# does not support metaclasses, the primitive types of Java and C# are ... From a perspective of theoretical study, there are some faults in the models of the existing object-oriented programming languages. For example, C# does not support metaclasses, the primitive types of Java and C# are not objects, etc. So, this paper designs a programming language, Shrek, which integrates many language features and constructions in a compact and consistent model. The Shrek language is a class-based purely object-oriented language. It has a dynamical strong type system, and adopts a single-inheritance mechanism with Mixin as its complement. It has a consistent class instantiation and inheritance structure, and the ability of intercessive structural computational reflection, which enables it to support safe metaclass programming. It also supports multi-thread programming and automatic garbage collection, and enforces its expressive power by adopting a native method mechanism. The prototype system of the Shrek language is implemented and anticipated design goals are achieved. 展开更多
关键词 dynamic typing metaclass programming computational reflection native method object-oriented programming language
下载PDF
Compressive properties and energy absorption characteristics of open-cell nickel foams 被引量:1
20
作者 范素峰 张涛 +6 位作者 余琨 房宏杰 熊汉青 戴翌龙 马家骥 姜大越 朱化龙 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2017年第1期117-124,共8页
Open-cell nickel foams with different relative densities and pre-stretching degrees were subjected to room temperature quasi-static compressive tests to explore their compressive properties. The compressive properties... Open-cell nickel foams with different relative densities and pre-stretching degrees were subjected to room temperature quasi-static compressive tests to explore their compressive properties. The compressive properties of the nickel foams including yield strength, elastic modulus, energy absorption density and energy absorption efficiency were calculated accurately. The results show that the compressive properties of yield strength, elastic modulus and energy absorption density increase with the increase of relative density of nickel foams. The compressive properties are sensitive to the pre-stretching degree, and the values of yield strength, elastic modulus and energy absorption density decrease with the increase of pre-stretching degree. However, the energy absorption efficiency at the densification strain state exhibits the independence of relative density and pre-stretching degree. The value of energy absorption efficiency reaches its peak when the strain is at the end of the collapse plateau region. 展开更多
关键词 nickel foam compressive property relative density pre-stretching degree
下载PDF
上一页 1 2 23 下一页 到第
使用帮助 返回顶部