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251.
校园网站是校园文化重要的展示窗口,更是信息化办工的高效工作平台,传统的静态网站只能在一定程度上展示图文信息,但随着时间的发展,内容的不断增多,传统校园网站的内容在更新、储存、查询等方面要寻求新的方法实现.通过ASP程序和数据库相接合,搭建一个B/S平台,从浏览器端获取信息,经过服务器处理后,呈现给浏览者的需要的信惠,实现浏览器端与服务器端的交互功能. 相似文献
252.
随着高校网络信息化的不断发展,网络安全问题开始日益突出,如何建立一套安全可行的校园网络安全系统,是所有高校校园网络管理者所需要解决的问题。 相似文献
253.
We propose a computing model, the Two-Way Optical Interference Automata (2OIA), that makes use of the phenomenon of optical interference. We introduce this model to investigate the increase in power, in terms of language recognition, of a classical Deterministic Finite Automaton (DFA) when endowed with the facility of interference. The question is in the spirit of Two-Way Finite Automata With Quantum and Classical States (2QCFA) [A. Ambainis, J. Watrous, Two-way finite automata with quantum and classical states, Theoret. Comput. Sci. 287 (1) (2002) 299–311] wherein the classical DFA is augmented with a quantum component of constant size. We test the power of 2OIA against the languages mentioned in the above paper. We give efficient 2OIA algorithms to recognize languages for which 2QCFA machines have been shown to exist, as well as languages whose status vis-a-vis 2QCFA has been posed as open questions. Having a DFA as a component, it trivially recognizes regular languages. We show that our model can recognize all languages recognized by 1-way deterministic blind counter automata. Finally we show the existence of a language that cannot be recognized by a 2OIA but which can be recognized by an O(n3) space Turing machine. 相似文献
254.
The job shop scheduling problem (JSP) is one of the most notoriously intractable NP-complete optimization problems. Over the last 10–15 years, tabu search (TS) has emerged as an effective algorithmic approach for the JSP. However, the quality of solutions found by tabu search approach depends on the initial solution. To overcome this problem and provide a robust and efficient methodology for the JSP, the heuristics search approach combining simulated annealing (SA) and TS strategy is developed. The main principle of this approach is that SA is used to find the elite solutions inside big valley (BV) so that TS can re-intensify search from the promising solutions. This hybrid algorithm is tested on the standard benchmark sets and compared with the other approaches. The computational results show that the proposed algorithm could obtain the high-quality solutions within reasonable computing times. For example, 17 new upper bounds among the unsolved problems are found in a short time. 相似文献
255.
256.
S. Saravanan A.K. Abdul Hakeem P. Kandaswamy J. Lee 《Computers & Mathematics with Applications》2008,55(12):2903-2912
Buoyancy driven convection in a square cavity induced by two mutually orthogonal arbitrarily placed heated thin plates is studied numerically under isothermal and isoflux boundary conditions. The flow is assumed to be two-dimensional. The coupled governing equations were solved by the finite difference method using the Alternating Direction Implicit technique and Successive Over Relaxation method. The steady state results are depicted in terms of streamline and isotherm plots. It is found that the resulting convection pattern is stronger for the isothermal boundary condition. A better overall heat transfer can be achieved by placing one of the plates far away from the center of the cavity for isothermal boundary condition and near the center of the cavity for isoflux boundary condition. 相似文献
257.
This paper describes the design and modelling of ultrasonic tomography for two-component high-acoustic impedance mixture such as liquid/gas and oil/gas flow which commonly found in chemical columns and industrial pipelines. The information obtained through this research has proven to be useful for further development of ultrasonic tomography. This includes acquiring and processing ultrasonic signals from the transducers to obtain the information of the spatial distributions of liquid and gas in an experimental column. Analysis on the transducers’ signals has been carried out to distinguish between the observation time and the Lamb waves. The information obtained from the observation time is useful for further development of the image reconstruction. 相似文献
258.
Using electric actuation and detection of oscillations in microcantilevers for pressure measurements
Gayatri Keskar Bevan Elliott Jay Gaillard Malcolm J. Skove Apparao M. Rao 《Sensors and actuators. A, Physical》2008,147(1):203-209
Response characteristics of a microcantilever, such as resonant frequency, amplitude, phase and quality factor, can be used for absolute pressure measurements in the range of 10−4 to 103 Torr. To this end, it would be very convenient to have the resonance of the microcantilever actuated and detected electrostatically. Herein, we report the nonlinear dynamics of microcantilevers under varying pressure and different gases using the harmonic detection of resonance (HDR) technique [J. Gaillard, M.J. Skove, R. Ciocan, A.M. Rao, Electrical detection of oscillations in 340 microcantilevers and nanocantilevers, Rev. Sci. Instrum. 77 (2006) 073907]. The HDR technique exploits nonlinearities in the cantilever-counter electrode system to allow electrostatic actuation and detection of the responses of the microcantilever to the pressure and gas composition. In particular, the 2nd and 3rd harmonics of the measured charge on the cantilever are investigated. The microcantilever demonstrates a quality factor of 10,000 at 10−3 Torr, and a usable response in the range from 10−3 to 103 Torr. The use of different harmonics can enable us to adjust the range of pressures over which the sensor has an efficacious response, enhancing its sensitivity to a particular environment. The experimental results are in reasonable agreement with theoretical calculations, despite the nonlinearities involved. 相似文献
259.
260.
A single feed circularly polarized fractal boundary microstrip antenna with improved axial ratio bandwidth is presented. The low‐axial ratio bandwidth of single feed circularly polarized microstrip antenna is due to its probe reactance. In this article, the inherent disadvantage of this low‐AR bandwidth is overcome by compensating the probe reactance by incorporating capacitance in the form of small patch between the radiating patch and the probe. The perturbation of the patch is done using fractal curve as boundary. The proposed antenna exhibits impedance and axial ratio bandwidths of 9 and 2.2% respectively at 2.4 GHz. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009. 相似文献