共查询到20条相似文献，搜索用时 31 毫秒
1.
Research on Stability Criterion of Concrete Feature in Different Stress Stage with Lyapunov Exponent
According to the research on whole curves of strain-stress of concrete materials,this paper finds there was an evident features of stages,and the discrete feature of curve is often in strain-softening stage.After data series of test being detected by dynamics of chaos,it presents that system of whole process of strain-stress evolutes from ordered steady state to low chaos state even high chaos state,system after compressive strength which curve of strain-stress is more linear one by one changes from strong ordered steady state to low chaos state;and joint system of concrete before compressive strength normally generates weak chaos state,with increase of uniaxial compressive strength of concrete materials specimens.The LE1 is proposed to be the stability criterion of concrete features in different stress stages,and the LE1 is regarded as the representative value of the system stability degree.The calculation of example shows that the stability criterion defined by the proposed method is consistent with the actual situation. 相似文献
2.
Economic chaos is a random-like dynamic behavior resulting from definitive economic system . Although the time series from economic system isn't forecasted in a long term ,but can be predicted precisely in a short term , thus , by which a deterministic model can be constructed . To search chaos character in economic time series , we present a combined forecasting method of economic chaos basing on genetic algorithms and the reconstruction of phase space given by Wolf, this method takes advantage of genetic algorithms to determine the weighting coefficient of combined forecasting. It's greatly overcome the defaults that when traditional forecasting of economic chaos single model is mostly used so as to affect the forecasting precision. At last , an example is given to testify the validity and feasibility of this method. 相似文献
3.
The acquisition of physiological signals is the first step of its analysis and processing. The development mode for PC/104 module is introduced and the design of multichannel acquisition system for physiological signals based on PC/104 is also put forward. The system hardware mainly includes PC/104 embedded computer,DIAMOND-MM-16-AT acquisition card and four-channel amplifiers. Windows 2000 is used as operating system for PC/104 embedded computer. The multithread program to sample data is made by means of programming language Visual C++ 6.0. The experimental results show that the system can be applied to sample, analyse, and process the physiological signals. The system also has lots of advantages, such as small volume, low power, firm structure and steady performance. 相似文献
4.
Yi Shuping Wu Yuanyi Xu Xiangsui 《保鲜与加工》1990,(4):34-40
Based on Group Technology, a CAD/CAPP integrated system is developed. This paper mainly covers the research work of the CAPP subsystem. In this subsystem, geometric and manufacturing information is obtained from the CAD data base, modular block programming and full Chinese menu are adopted, process planning is produced with the semi-generative method, and process card involved the operation charts is yielded by printer.
The operation is simple and convenient, and the performance is quick. The ? CAPP subsystem is successfully integrated with the CAD subsystem. The subsystem is an advanced CAPP system. 相似文献
5.
Since there exists multi-protocol attack when several security protocols are co-executed in a computer network, an automatic detection system for multi-protocol attack (ADMA) is proposed. The system is composed of two parts named protocol search subsystem and attack verification subsystem. According to the consistency condition of the type of encrypted messages between the target protocol and the secondary protocol, the protocol search subsystem can automatically search for the candidate secondary protocols, which may be used to attack the target protocol. By improving the SAT-based model checking, attack verification subsystem can automatically verify whether multi-protocol attack exists between the target protocol and the candidate secondary protocols or not. The experiment results show that ADMA system can implement automatic detection for multi-protocol attack, and some new multi-protocol attacks are found in the detection. 相似文献
6.
棉铃虫灾变预警与辅助防治决策系统(MLCYJC-CDROM)研究 总被引：2，自引：0，他引：2
依据棉铃虫灾变预警与防治决策及系统分析原理 ,采用结构化分析与结构化设计和面向对象的设计方法 ,应用 VB编程开发而成。整个系统是一个融灾变预警与辅助防治决策信息的实况输入、数据处理、作用评估及结果输出于一体的实用性较强的计算机应用系统。其中灾变预警亚系统由灾变预警指标体系与灾变警级评估警报体系组成。辅助防治决策亚系统既接受灾变预警亚系统的信息传输 ,也含有辅助防治决策相关信息。据此确定棉铃虫灾变预警警级的等级 ,并指导综合防治决策 ,可使灾变警级预警更加符合实际 ,指导减灾防治更有科学依据 相似文献
7.
In existing equipment vehicle transmission test bed can be controlled only by 8031 SCM and data can not be transmitted from SCM to PC. In order to take most advantage of available equipment, data transfer between PC and Multi SCM is put forward. By this way, torque of eddycurrent dynamometer can be controlled by PC programs and satisfy the needs of torque convert experiment. Making use of Dynamic Link Library 8250 registers can be read and written directly. Programs can set the ninth bit easily without Microsoft Communication Control. Data are transmitted between PC and Multi SCM though RS232 COM successfully by using Visual Basic programs. Cost and time are sharply reduced. 相似文献
8.
The traditional method of generating pseudorandom phase vector through a linear feedback shift register (LFSR) and a pre set combination of taps in transform domain communication system(TDCS) was studied. Based on the requirements of the pseudorandom phase vector in TDCS, a new method using chaos mapping to generate the pseudorandom phases in TDCS was proposed. This method generated binary quantization chaotic sequences by using chaos mapping with different initial values, and then creates a pseudorandom phase vector by using a phase mapper. Finally, the basis function was obtained. The implementation method of chaos mapping and the simulation results regarding the correlation performance for the basis function were discussed in detail. Compared with the basis functions generated by LFSR, the basis functions generated by chaos mapping have better correlation performance. Because many basis functions with small cross correlation coefficients can be generated by chaos mapping, this method is advantageous for multiple access applications. 相似文献
9.
By modern cybernetics, we can find out a state feedback for a linear time system, which does not change the controllability and stability of the system. But whether a state feedback for linear time system can be found out, which does ont change observability of the system or not, so far hasn't been discussed. The problem is studied according to the steady discrete time linear system, and a state feedback is found out, which does ont change the controllability, observability and stability, by relation of stability, observability and characteristic root, rank of matrix, of steady discrete time linear system; the method of how to construct the state feedback is given. 相似文献
10.
Equivalent linear system method is the main method of nonlinear structural system random response analysis. While it would generate big error when the results of equivalent linear system method are used to analyze the structural dynamic reliability. Through minimum mean square error principle, general nonlinear system was converted to equivalent Duffing nonlinear system, based on which the structural dynamic reliability was analyzed. The accurate steady state analytic solution of Duffing nonlinear system can be worked out by FPK equation, so it is not only convenient but also accurate to analyze structural dynamic reliability by using the equivalent nonlinear system method. It is also shown that the analysis results of equivalent nonlinear system method presented here is reliable and the calculation accuracy is higher than equivalent linear system method apparently through the example analysis. 相似文献
11.
在全球变暖的大背景下,干旱已成为本溪地区主要气象灾害之一。本研究利用VB 6.0和Access数据库管理等现代技术,开发建成了“本溪地区干旱监测评估系统”。该系统包括气候资料数据库子系统、气候影响客观评价子系统、干旱指标库、干旱灾害历史数据库查询子系统、干旱产品服务子系统5个部分,能够进行大气干旱Z 指数和农业干旱β 指数模型的自动计算,可实现对全地区干旱监测、分析和评估等业务工作的支持,为大气和农业等领域的干旱监测评估工作提供丰富的图形、表格和文本等数据信息,为农业生产决策提供科学的依据。 相似文献
12.
GONG Xian sheng 《保鲜与加工》1999,(3):15-23
A method which is used for calculating steady vibration response of shipping propulsion shafting connecting with a coupling with nonlinear hysteresis characteristics are studied. On condition that the nonlinear dynamic stiffness and hysteresis damping of the coupling be considered, on the basis of GLM(Galerki Levenberg Marquard) method, a method called SSGILM(Separate System Galerkin and Improved Levenberg-Marquardt)to be used for calculating steady vibration response of propulsion shafting with local nonlinear dynamic stiffness and hysteresis damping, is proposed. A simple example is given out and the analyses show that it is effective to calculate steady vibration response of the shafting with local nonlinear dynamic stiffness and hysteresis damping by SSGILM method. From initial response values given arbitrarily, the automatic search algorithm in SSGILM method can converge the given initial response values to the response values accorded with required accuracy quickly; nonlinear dynamic stiffness and hysteresis damping of the coupling have different effect on vibration response of the shafting at different range of frequency. At the area of close nature frequency of the shafting ,displacement amplitude of the shafting is bigger. Beyond the range, the characteristics of the coupling have restraint effect on vibration of the shafting. 相似文献
13.
Operational Deflection Shapes of large scale electromechanical system can be ex-tracted directly from multipoints response of the operating system by using of the modal shape analy-sis method. Thev can be used for engineers evaluating the practical dynamic beavior of the largescale elecltromechanical system,checking the existence of local reso,iance of the Stibsystem. and in-dentifying the wcakened positions of the rigidity of structure, In this paper the method of measuringand extracting the operational deflection shal1e of the electromecha nical system is given and theavailability of operational deflection shape is proved by analyzing the actual vibration of a large ex-haust fan system as an example. 相似文献
14.
基于GIS的辽宁省农田水利管理信息系统研究 总被引：4，自引：0，他引：4
为改善辽宁省农田水利长期以来传统的管理方法,应用先进的科技手段3S技术提高灌区管理水平是现代农业发展的必然趋势。从辽宁省管理部门的实际出发,设计开发了基于GIS的农田水利管理信息系统,系统由灌溉子系统模块、排涝子系统模块、农村饮水子系统模块、报表系统模块和权限管理模块组成,具有一定的智能水平,大大改善了辽宁省农田水利的全方位管理。 相似文献
15.
为实现黑龙江省农业可持续性发展,运用复杂系统的观点研究分析了农业发展的特点,将黑龙江农业发展系统划分为农业经济、农业技术、农村社会、农业环境4个子系统。在此基础上,通过分析各子系统间的关联及影响机理,利用Vensim DSS软件及《黑龙江省统计年鉴》等历史数据,经过参数估计及有效性检验,从而建立并完善了黑龙江农业可持续发展的系统动力学模型。然后对黑龙江省2005—2020年农业各子系统发展的可持续性进行仿真模拟与预测。结果发现黑龙江省的农业经济可持续度发展最好,农业技术次之,农业社会与生态环境可持续性最差。 相似文献
16.
北京市现代农民远程教育与培训体系建设、成效与思考 总被引：6，自引：0，他引：6
随着网络技术的成熟和信息时代的到来,中国农民教育与培训面临全新的挑战和机遇。对北 京市现代农民远程教育与培训体系建设内容,从综合网络技术系统建设、学习支持系统建设、教育资 源系统的开发、远程接收系统建设、组织管理服务系统建设五方面进行了阐述。并对取得成效进行了 介绍;以及对体系建设过程中存在的问题进行了进一步的分析,包括基层人才、信息资源建设、培训 过程的交互性、以及远程站点利用与发展等问题,以期为中国现代农民远程教育与培训体系的建设 提供参考。 相似文献
17.
On the basis of a planetary transmission, a novel hydrodynamic speed controlled transmission system for wind turbines with large capacity is presented. The new drive train consists of wind rotors, planet accelerators, hydro-mechanical and synchronous generators. The dynamic mathematical model of the drive train is established. The digital simulation of speed regulation characteristics for hydrodynamic speed controlled system is studied by using Matlab/Simulink. The simulation results show that continuously variable transmission and fixed speed control can be achieved, and the drive train works well in stability and dynamic performances. They can increase the power yield from the wind, smooth the electric power output, and alleviate the load peak in the new drive train . 相似文献
18.
关于系统耦合理论的探讨 总被引：8，自引：0，他引：8
系统耦合理论是近年来研究的热点问题。以农牧交错带为例,针对在生态经济系统目前该理论的定量化方面研究不足的事实,提出用能值方法考虑农牧交错带系统耦合的机制,并指出农牧交错带系统耦合机制应建立在土地利用方式、子系统间能值转化过程和生态系统的能值储备上;同时影响系统耦合机制的主要因素有初级生产力的大小、畜牧业的内部结构和畜牧业的发展规模以及生态系统服务价值的大小。还探讨性地提出系统耦合度的概念化公式,期望能更好地应用并发展这一理论。 相似文献
19.
Chaos control based disease control has become a new direction for medical research. Chaos control can improve the study of nervous system diseases. To explain the inherent characteristics of such treatment with neurophysiology, a neuron dynamic simulation model, based on the Chay model, was built with MATLAB/SIMULINK. Various stimulations were inserted to analyze the dynamic change of the neuron action potential and its chaos expression. The experimental results show that different internal and external stimulations to the nervous system have great influence on membrane potential and chaos expression, indicating the importance and feasibility of chaos control in disease control. 相似文献
20.
《Journal of Landscape Research》2017,(2)
Urban ecological infrastructure is the ecological background of urban sustainable development and is the basic guarantee for the construction of ecological cities. According to the characteristics of the ecological infrastructure of coal-based cities, the ecological infrastructure is divided into two subsystems:natural infrastructure subsystem and artificial infrastructure subsystem. According to each subsystem and its main components(such as atmosphere, green space, hydrology, traffic and transportation), 36 indicators were selected to establish the evaluation system. In addition, the evaluation model was established by means of mean square deviation method and composite index method, and a dynamic analysis was carried out on the ecological infrastructure quality of Huainan City in 2006-2015. The results show that the composite index of ecological infrastructure in Huainan City in 2006-2015 remained at the medium level, and the natural infrastructure at the worse and poor levels, while the artificial infrastructure remained at the medium and excellent levels. 相似文献