期刊文献+
共找到59篇文章
< 1 2 3 >
每页显示 20 50 100
双面金属包覆介质波导模序数的判别方法 被引量:12
1
作者 周峰 曹庄琪 +1 位作者 蒋毅 沈启舜 《光学学报》 EI CAS CSCD 北大核心 2002年第6期665-669,共5页
在双面金属包覆介质波导中 ,随着介质层厚度的变化 ,会出现TM0 模与TM1 模的分离和简并两种状态 ,从而影响衰减全反射 (ATR)谱中模序数的确认。通过对金属波导的理论分析和实验研究 ,提出了三种模序数确认方法 :本征角计算法、吸收峰全... 在双面金属包覆介质波导中 ,随着介质层厚度的变化 ,会出现TM0 模与TM1 模的分离和简并两种状态 ,从而影响衰减全反射 (ATR)谱中模序数的确认。通过对金属波导的理论分析和实验研究 ,提出了三种模序数确认方法 :本征角计算法、吸收峰全峰半宽比较法和吸收峰峰间距比较法 。 展开更多
关键词 双面金属包覆介质波导 判别方法 衰减全反射 模序数
原文传递
LPFG镀层参数对其折射率传感特性的仿真分析 被引量:1
2
作者 周艳 王天根 郭冰 《激光与红外》 CAS CSCD 北大核心 2018年第1期99-103,共5页
长周期光纤光栅在传感测量领域具有防爆、防磁、抗干扰等优点,且对周围介质折射率的变化敏感,适用于矿井、油田等易燃、易爆、强电磁干扰环境及具有毒性、腐蚀性等不宜接触的液体的折射率测量。本文采用在长周期光纤光栅包层外沿径向镀... 长周期光纤光栅在传感测量领域具有防爆、防磁、抗干扰等优点,且对周围介质折射率的变化敏感,适用于矿井、油田等易燃、易爆、强电磁干扰环境及具有毒性、腐蚀性等不宜接触的液体的折射率测量。本文采用在长周期光纤光栅包层外沿径向镀一金属薄层的方式,从长周期光纤光栅传感原理着手,利用三包层模型的本征方程,并借助MATLAB进行方程求解和仿真分析,讨论了包层模序数、光栅周期、膜层厚度等参数与谐振峰中心波长偏移的关系。为合理选择光栅结构参数、制作符合要求的长周期光纤光栅用于折射率传感测量提供了依据。 展开更多
关键词 镀膜LPFG 折射率传感 模序数 光栅周期 膜厚
下载PDF
New Methods to Solve Fuzzy Shortest Path Problems 被引量:3
3
作者 刘春林 何建敏 施建军 《Journal of Southeast University(English Edition)》 EI CAS 2001年第1期18-21,共4页
This paper discusses the problem of finding a shortest path from a fixed origin s to a specified node t in a network with arcs represented as typical triangular fuzzy numbers (TFN). Because of the characterist... This paper discusses the problem of finding a shortest path from a fixed origin s to a specified node t in a network with arcs represented as typical triangular fuzzy numbers (TFN). Because of the characteristic of TFNs, the length of any path p from s to t , which equals the extended sum of all arcs belonging to p , is also TFN. Therefore, the fuzzy shortest path problem (FSPP) becomes to select the smallest among all those TFNs corresponding to different paths from s to t (specifically, the smallest TFN represents the shortest path). Based on Adamo's method for ranking fuzzy number, the pessimistic method and its extensions - optimistic method and λ combination method, are presented, and the FSPP is finally converted into the crisp shortest path problems. 展开更多
关键词 triangular fuzzy number fuzzy shortest path ranking function
下载PDF
The Structures of the AR Sequences of Tilted Algebras
4
作者 章璞 《Chinese Quarterly Journal of Mathematics》 CSCD 1992年第3期58-65,共8页
In this paper,We give the forms of AR sequences of a tilted algebra with terms all belonging to x(A_T),or all belonging to y(A_T).The sink maps of a tilted algebra which end at the indecompos able projective modules a... In this paper,We give the forms of AR sequences of a tilted algebra with terms all belonging to x(A_T),or all belonging to y(A_T).The sink maps of a tilted algebra which end at the indecompos able projective modules and the source maps of starting at the indecomposable injective modules are also obtained.These results together with the connecting sequecnes given in [3] determine the AR quiver of the tilted algcbra,morever,this can be done directly from the AR quiver of the correspond ing hereditary algebra. 展开更多
关键词 tilted algebra AR sequences
下载PDF
Method based on fuzzy linguistic scale and FIOWGA operator for decision-making problems 被引量:3
5
作者 徐泽水 达庆利 《Journal of Southeast University(English Edition)》 EI CAS 2003年第1期88-91,共4页
In this paper, we present a fuzzy linguistic scale, which is characterized by triangular fuzzy numbers on [1/9, 9], for the comparison between two alternatives, and introduce a possibility degree formula for comparing... In this paper, we present a fuzzy linguistic scale, which is characterized by triangular fuzzy numbers on [1/9, 9], for the comparison between two alternatives, and introduce a possibility degree formula for comparing triangular fuzzy numbers. We utilize the fuzzy linguistic scale to construct a linguistic preference matrix, and propose a fuzzy induced ordered weighted geometric averaging (FIOWGA) operator to aggregate linguistic preference information. A method based on the fuzzy linguistic scale and FIOWGA operator for decision-making problems is presented. Finally, an illustrative example is given to verify the developed method and to demonstrate its feasibility and effectiveness. 展开更多
关键词 fuzzy linguistic scale triangular fuzzy numbers FIOWGA operator
下载PDF
On Spatial Distribution Pattern of Broccoli Clubroot Disease and and the Sampling Technique
6
作者 钟列权 王会福 余山红 《Agricultural Science & Technology》 CAS 2015年第12期2715-2719,共5页
[Objective] To further improve the prediction and forecast and continuous control ability of broccoli clubroot disease. [Methods] The spatial distribution pattern of diseased or infected plants was analyzed using the ... [Objective] To further improve the prediction and forecast and continuous control ability of broccoli clubroot disease. [Methods] The spatial distribution pattern of diseased or infected plants was analyzed using the least square method, fre- quency distribution, aggregation index, m*-m regression analysis and Taylor's pow- er law model. [Result] The field distribution of broccoli plants with clubroot disease tended to be aggregated distribution, m'-m regression analysis showed that the el- ementary composition of the spatial distribution of diseased or infected plants was individual colony, the individuals attracted each other; the disease had obvious dis- ease focus in the field, and the individual colony showed uniform distribution pattern in the field. Taylor's power law showed that the spatial pattern of individual dis- eased or infected plant with clubroot disease tended to be uniform distribution with the increase of the density. On the basis of this, Iwao optimal theoretical sampling model and sequential sampling model were established, namely N =273.954 1/m- 59.698 5, To (N)=0.368 4N±1.926 8√N, respectively, it meant that when surveying N plants, if the accumulative incidence rate exceeded upper bound, the field can be set as control object; if the accumulative incidence rate didn't reach lower bound, it can be set as uncontrol field; if the accumulative incidence rate was between upper bound and lower bound, it should be surveyed continuously until the maximum sample size (mo=0.368 4) appeared, that was, the disease incidence was 15%, so the sampling number should be 684 plants. [Conclusion] The research results had very important instructive meaning for disease control. 展开更多
关键词 Broccoli clubfoot disease Spatial distribution pattern The optimal theo- retical sampling model Sequential sampling model Sampling number
下载PDF
Improvement of the Mirror Extending in Empirical Mode Decomposition Method and the Technology for Eliminating Frequency Mixing 被引量:32
7
作者 赵进平 《High Technology Letters》 EI CAS 2002年第3期40-47,共8页
The mirror extending approach proposed by Zhao and Huang in EMD method is improved in this paper. Mirror extending manner of data is kept unchanged, but the approach for determining envelopes is changed. When the end ... The mirror extending approach proposed by Zhao and Huang in EMD method is improved in this paper. Mirror extending manner of data is kept unchanged, but the approach for determining envelopes is changed. When the end of data is obviously not extremum, the envelope is determined by the first inner extremum and the image value in the mirror, ignoring the value on the end. This improvement eliminates the frequency compression near the end and decreases the error. Meanwhile, tridiagonal equations are used and the calculation speed is much increased. The temporal process curve is more important in reflecting the real physical process and comparable with other phenomena. Frequency mixing in IMFs makes it impossible. A high frequency reconstruction (HFR) approach is proposed to eliminate common frequency mixing and reconstruct an IMF with all high frequency portions. By this approach, the IMFs without frequency mixing are obtained to express significative processes. The high frequency information restored in high frequency IMF can be extracted by general spectrum method. After obtaining IMFs by EMD method, some of the theoretical and technological issues still exist when using the IMFs. The consistency of IMFs with real physical process is discussed in detail. By virtue of the approach proposed in this paper, the EMD method can be widely used in various fields. 展开更多
关键词 empirical mode decomposition mirror extending intrinsic mode function high frequency reconstruction frequency mixing
下载PDF
Chaos Control in a New Three-Dimensional Chaotic T System 被引量:5
8
作者 CHEN Yong YAN Zhen-Ya 《Communications in Theoretical Physics》 SCIE CAS CSCD 2008年第4期951-954,共4页
In this paper, we study chaos control of the new 3D chaotic system. We use three feedback methods (the linear, speed, doubly-periodic function controller) to suppress the chaos to unstable equilibrium. As a result, ... In this paper, we study chaos control of the new 3D chaotic system. We use three feedback methods (the linear, speed, doubly-periodic function controller) to suppress the chaos to unstable equilibrium. As a result, some controllers are obtained. Moreover, numerical simulations are used to verify the effectiveness of the obtained controllers. 展开更多
关键词 chaos control chaotic T system feedback control Routh-Hurwitz theorem numerical simulation
下载PDF
Research on parametric modeling and computing of multi-tower suspension bridge based on ANSYS 被引量:1
9
作者 Feng Zhaoxiang Zhao An +1 位作者 Song Jianyong Yang Yun 《Engineering Sciences》 EI 2012年第3期49-54,共6页
Based on FEM (finite element method) program ANSYS and the OpenGL graphics, this paper develops the parametric modeling module and the computing module of the multi-tower suspension bridge, the modules being embedded ... Based on FEM (finite element method) program ANSYS and the OpenGL graphics, this paper develops the parametric modeling module and the computing module of the multi-tower suspension bridge, the modules being embedded into the ANSYS system, and the parametric modeling module parameters can be entered by way of interface, which can fast establish a multi-tower suspension bridge model. Calculation module can establish load conditions for the features of road bridge and specifications, in which multiple conditions can be defined and solved automatically. Post-processing part of the solution also serves the results of the subtotals and selects the output, so that the results of the output and finishing work have become more convenient and easier, and also the results can be saved in word, excel and other different file types. 展开更多
关键词 ANSYS suspension bridge parametric modeling COMPUTING
下载PDF
The Semimodularity of Cardinal Power of Posets
10
作者 胡长流 《Chinese Quarterly Journal of Mathematics》 CSCD 1997年第1期47-51, ,共5页
Let X,Y be any posets,the semimodularity of cardinal power Yx with base Y and exponent X is studied. Some necessary or sufficient conditions for Yx to be semimodular are gaven,
关键词 POSET cardinal power of posets seimodularity
下载PDF
Modeling the growth and policy implications of Global System for Mobile Telecommunication (GSM) in Nigeria
11
作者 Bakare Adewale Stephen 《Chinese Business Review》 2010年第10期33-40,共8页
This paper investigated the growth and policy implications of Global System for Mobile Communication in Nigeria. Stochastic economic modeling was used to analyze Nigeria's time series data. The models were adjudged r... This paper investigated the growth and policy implications of Global System for Mobile Communication in Nigeria. Stochastic economic modeling was used to analyze Nigeria's time series data. The models were adjudged reliable before they were used. The components of the model were defined and a prior expectation of the relationship among the variables explained for the purpose of giving the reviewers and users a deep insight into the phenomenon under study. The secondary data used for the study were processed using the E-View for windows electronic packages. The outcome of the empirical and stochastic investigations shows that Global System for Mobile Communication has a positive relationship with output growth in Nigeria. The impact is of a higher magnitude. The usage of Global System for Mobile Telecommunication led to 17 percent rise in the output growth. The findings suggest the need for the Nigerian Communication Commission (NCC) and the federal government of Nigeria to expand tele-density and directly make telephone communications cheap and accessible. To achieve this goal, more licenses should be given to GSM operators in order to allow for healthy competition among them. This will lead to improved quality of services, quality of product and consequently sustain the growth and development of the country. 展开更多
关键词 Global System for Mobile Communication (GSM) tele-density economic growth DEREGULATION
下载PDF
Dynamic Response of Functional Virtual Prototyping of Motorcycle under Combined Excitations 被引量:1
12
作者 孙立星 舒歌群 卫海桥 《Transactions of Tianjin University》 EI CAS 2013年第4期279-286,共8页
This paper developed 3D product models of motorcycle and engine by UGNX as well as virtual prototyping by ADAMS program with road roughness generated by MATLAB. Under the straight-line running condition, the dynamic r... This paper developed 3D product models of motorcycle and engine by UGNX as well as virtual prototyping by ADAMS program with road roughness generated by MATLAB. Under the straight-line running condition, the dynamic responses of motorcycle multibody system to both road and engine excitations were compared with those to only road excitation in terms of vertical acceleration response, amplitude frequency response and power spectral density. The comparisons of simulation data showed that the response due to flat road excitation was around 20 Hz, while that to the combined excitations was in a wide frequency band, of which the major components focused on 10 Hz, 15 Hz, 35 Hz ,70 Hz, 100 Hz and even higher frequencies, reflecting the characteristics of engine excitation based on its unbalanced inertia force and torque. It is concluded that the high fidelity virtual prototyping can simulate the dynamics of motorcycle product well in investigating the vibration and ride comfort performance. 展开更多
关键词 multibody dynamics engine excitation road excitation motorcycle dynamic response
下载PDF
Hybrid heuristic and mathematical programming in oil pipelines networks: Use of immigrants
13
作者 DE LA CRUZ J.M HERRáN-GONZáLEZ A +1 位作者 RISCO-MARTíN J.L ANDRéS-TORO B 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2005年第1期9-19,共11页
We solve the problem of petroleum products distribution through oil pipelines networks. This problem is modelled and solved using two techniques: A heuristic method like a multiobjective evolutionary algorithm and Mat... We solve the problem of petroleum products distribution through oil pipelines networks. This problem is modelled and solved using two techniques: A heuristic method like a multiobjective evolutionary algorithm and Mathematical Programming. In the multiobjective evolutionary algorithm, several objective functions are defined to express the goals of the solutions as well as the preferences among them. Some constraints are included as hard objective functions and some are evaluated through a repairing function to avoid infeasible solutions. In the Mathematical Programming approach the multiobjective optimization is solved using the Constraint Method in Mixed Integer Linear Programming. Some constraints of the mathematical model are nonlinear, so they are linearized. The results obtained with both methods for one concrete network are presented. They are compared with a hybrid solution, where we use the results obtained by Mathematical Programming as the seed of the evolutionary algorithm. 展开更多
关键词 MOEA MILP Hybrid algorithm CONSTRAINTS
下载PDF
Lacunary Invariant Statistical Convergence Of Sequences Of Sets With Respect To A Modulus Function
14
作者 Nimet Pancaroglu Fatih Nuray 《Journal of Mathematics and System Science》 2015年第3期122-126,共5页
In this paper, we introduce and study the concept of lacunary invariant convergence for sequences of sets with respect to modulus functionfand give some inclusion relations.
关键词 Statistical convergence lacunary invariant convergence sequences of sets modulus function
下载PDF
A CFD model for gas uniform distribution in turbulent flow for the production of titanium pigment in chloride process 被引量:4
15
作者 Yadong Li Gang Xie +3 位作者 Ting Lei Chongjun Bao Lin Tian Yanqing Hou 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2016年第6期749-756,共8页
The fluid dynamic behavior of feeding gas (TiCI4) in an annular channel affects the combination of 02 and TiCI4 in an oxidation reactor, a key piece of equipment in titanium pigment production. The numerical procedu... The fluid dynamic behavior of feeding gas (TiCI4) in an annular channel affects the combination of 02 and TiCI4 in an oxidation reactor, a key piece of equipment in titanium pigment production. The numerical procedure was validated by a 3-dimensional gas flow in the annular channel. Applying the validated model, the flow character- istics of TiCl4 in the oxidation reactor with a tangential inlet were simulated and characterized. The flow distribu- tion with five rectifying rings of different structure was simulated and analyzed. The results showed that the rectifying ring improved the distribution uniformity of the pressure and outlet velocity. Compared to the original case without a rectifying ring, the non-uniformity of the pressure and outlet velocity could be reduced by up to 91% and 69% respectively. The rectifying ring #5, which can be installed and adjusted easily, is more effective in realizing even distribution. In addition, installation of the rectifying ring effectively reduced the circulating flow in an annular channel as well as the total energy loss. 展开更多
关键词 Oxidation reactorChloride processRectifying ringComputational fluid dynamicsDimensionless pressure
下载PDF
Rapid Convergence of a New Wave Iterative Algorithm Used to Model a Patch Structure
16
作者 Hafedh Hrizi Lassaad Latrach +3 位作者 Noureddine Sboui Ali Gharsallah Abdelhafidh Gharbi Henry Baudrand 《Computer Technology and Application》 2011年第5期370-373,共4页
The wave iterative method is a numerical method used in the electromagnetic modeling of high frequency electronic circuits. The object of the authors' study is to improve the convergence speed of this method by addin... The wave iterative method is a numerical method used in the electromagnetic modeling of high frequency electronic circuits. The object of the authors' study is to improve the convergence speed of this method by adding a new algorithm based on filtering techniques. This method requires a maximum number of iterations, noted Nmax, to achieve the convergence to the optimal value. This number wilt be reduced in order to reduce the computing time. The remaining iterations until Nmax will be calculated by the new algorithm which ensures a rapid convergence to the optimal result. 展开更多
关键词 Wave iterative method rapid convergence adaptive and autoregressive filtering (AARF) patch structure
下载PDF
Nonlinear flow numerical simulation of low-permeability reservoir 被引量:2
17
作者 于荣泽 卞亚南 +3 位作者 周舒 王楷军 吕琦 陈朝辉 《Journal of Central South University》 SCIE EI CAS 2012年第7期1980-1987,共8页
A nonlinear flow reservoir mathematical model was established based on the flow characteristic of low-permeability reservoir.The well-grid equations were deduced and the dimensionless permeability coefficient was intr... A nonlinear flow reservoir mathematical model was established based on the flow characteristic of low-permeability reservoir.The well-grid equations were deduced and the dimensionless permeability coefficient was introduced to describe the permeability variation of nonlinear flow.The nonlinear flow numerical simulation program was compiled based on black-oil model.A quarter of five-spot well unit was simulated to study the effect of nonlinear flow on the exploitation of low-permeability reservoir.The comprehensive comparison and analysis of the simulation results of Darcy flow,quasi-linear flow and nonlinear flow were provided.The dimensionless permeability coefficient distribution was gained to describe the nonlinear flow degree.The result shows that compared with the results of Darcy flow,when considering nonlinear flow,the oil production is low,and production decline is rapid.The fluid flow in reservoir consumes more driving energy,which reduces the water flooding efficiency.Darcy flow model overstates the reservoir flow capability,and quasi-linear flow model overstates the reservoir flow resistance.The flow ability of the formation near the well and artificial fracture is strong while the flow ability of the formation far away from the main streamline is weak.The nonlinear flow area is much larger than that of quasi-linear flow during the fluid flow in low-permeability reservoir.The water propelling speed of nonlinear flow is greatly slower than that of Darcy flow in the vertical direction of artificial fracture,and the nonlinear flow should be taken into account in the well pattern arrangement of low-permeability reservoir. 展开更多
关键词 low-permeability reservoir nonlinear flow mathematical model numerical simulation
下载PDF
Modelling of Wage and Income Distributions Using the Method of L-Moments 被引量:1
18
作者 Diana Bilkova 《Journal of Mathematics and System Science》 2012年第1期13-19,共7页
Commonly used statistical procedure to describe the observed statistical sets is to use their conventional moments or cumulants. When choosing an appropriate parametric distribution for the data set is typically that ... Commonly used statistical procedure to describe the observed statistical sets is to use their conventional moments or cumulants. When choosing an appropriate parametric distribution for the data set is typically that parameters of a parametric distribution are estimated using the moment method of creating a system of equations in which the sample conventional moments lay in the equality of the corresponding moments of the theoretical distribution. However, the moment method of parameter estimation is not always convenient, especially for small samples. An alternative approach is based on the use of other characteristics, which the author calls L-moments. L-moments are analogous to conventional moments, but they are based on linear combinations of order statistics, i.e., L-statistics. Using L-moments is theoretically preferable to the conventional moments and consists in the fact that L-moments characterize a wider range of distribution. When estimating from sample L-moments, L-moments are more robust to the presence of outliers in the data. Experience also shows that, compared to conventional moments, L-moments are less prone to bias of estimation. Parameter estimates obtained using L-moments are mainly in the case of small samples often even more accurate than estimates of parameters made by maximum likelihood method. Using the method of L-moments in the case of small data sets from the meteorology is primarily known in statistical literature. This paper deals with the use of L-moments in the case for large data sets of income distribution (individual data) and wage distribution (data are ordered to form of interval frequency distribution of extreme open intervals). This paper also presents a comparison of the accuracy of the method of L-moments with an accuracy of other methods of point estimation of parameters of parametric probability distribution in the case of large data sets of individual data and data ordered to form of interval frequency distribution. 展开更多
关键词 L-MOMENTS method of L-moments of parameter estimation lognormal distribution wage distribution income distribution.
下载PDF
Conditional Quantile Polynomial Distributed Lag Model with an Application to Rubber Price Returns
19
作者 Kwadwo Agyei Nyantakyi 《Journal of Physical Science and Application》 2015年第2期108-115,共8页
Impacts of returns on assets are not instantaneously felt, since there is lag period. In this paper we consider the problem of developing a model for the conditional QPDL (quantile polynomial distributed lag) and in... Impacts of returns on assets are not instantaneously felt, since there is lag period. In this paper we consider the problem of developing a model for the conditional QPDL (quantile polynomial distributed lag) and investigate the influences of the conditioning variables on the location, scale and shape parameters of the QPDL model. As an economic application, we consider the production of rubber and its price returns ofSri Lanka. From the analysis we observed that the QPDL model applications were better estimators than the PDL (Polynomial Distributed Lag) models. 展开更多
关键词 Asset returns PERCENTILES parameter estimators production.
下载PDF
Estimation of Number Of Small Cattle Through ARIMA Models in Turkey
20
作者 Senol CELIK 《Journal of Mathematics and System Science》 2015年第11期464-473,共10页
In this study, the number of sheep and goats in Turkey were analysed by time series analysis method, and the number of great cattle for next years predicted through the most appropriate time series model.Time series w... In this study, the number of sheep and goats in Turkey were analysed by time series analysis method, and the number of great cattle for next years predicted through the most appropriate time series model.Time series was formed using the data on the number of sheep and goats belonging to the period between 1930 and 2014 in Turkey It was determined through autocorrelation function graphic that the series weren't stationary at first, but they became stationary after their first difference were calculated. A stagnancy test was performed through extended Dickey-Fuller test. So as to determine the suitability of the model, it was reviewed if autocorrelation and partial autocorrelation graphs were white noise series and also the results of Box-Ljung test were reviwed. Through the "tested models, the model estimations, of which parameter estimates were significant and Akaike information criterion (AIC) was the smallest, were performed. The most appropriate model in terms of both the number of sheep and goats is first-level integrated moving average model stated as ARIMA(0,1,1). In this model, it was estimated that there would be an increase in the number of sheep and goats in Turkey between the years of 2015 and 2020, however, the increase in the number of sheep would be more than the increase in the number of goats. 展开更多
关键词 ARIMA Models AUTOCORRELATION the number of sheep the number of goats.
下载PDF
上一页 1 2 3 下一页 到第
使用帮助 返回顶部