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1.
INTRODUCTIONItiswell knownthatcertificationauthority(CA)isthecorecomponentofpubliccrypto graphicinfrastructure (PKI) ;andthatthesecu rityofitsprivatekeyisveryvital.Iftheprivatekeyiscompromised ,thewholePKIwillbecor rupted .Generally,therearetwotypesofCA :…  相似文献   

2.
Cluster parallel rendering based on encoded mesh   总被引:2,自引:0,他引:2  
INTRODUCTION Three dimensional (3D) meshes are widely used to represent 3D objects. With the rapid advances in digital acquisition technology, meshes with millions of vertices are becoming increasingly common. Be- cause of memory constraints and lack of graphics power, visualizations of this magnitude are difficult or impossible to perform even on the most powerful workstations. Therefore, the need for parallel im- plementation is clear. Most previous work in high performance rendering h…  相似文献   

3.
INTRODUCTION Dementia is becoming a big problem in modern life, and particularly, it takes place more frequently in mental job group and the elderly. Today, more than 20 million people in the world catch this disease (Francis et al., 1999; Almkvist et al., 1998). So how to detect underlying dementia and take preventive measure is critical for both the doctors and their patients. People with dementia always behave slowly and their memory decreases with the development of the disease. Curr…  相似文献   

4.
A novel asymmetrical pitch system for rotary wing is presented. The pitch control characteristics are studied and analyzed. Because elastic linkage is a key part in whole asymmetrical pitch system, in order to obtain the variation of the elastic linkage deformation, an experimental platform mainly based on the device of micro aerial vehicles (MAVs) and a new control system mounted on TMS320LF2407 are designed. This control system has its compacted configuration and reliability. Finally, using this system to control the MAV for simulating the flying forward, experimental results show the MAV’s flight attitude can be controlled based on the variation of the elastic linkage. Project supported by the National Natural Science Foundation of China (Grant No.60605028), the National High-Technology Research and Development Program of China (Grant No.2007AA04Z225), the Shanghai Rising-Star Program (Grant Nos.07QA14024, 07QH14006), the Shanghai Shuguang Program (Grant No.07SG47), and the Shanghai Leading Key Laboratory of Mechanical Automation and Robotics Science Foundation (Grant No.ZZ0805)  相似文献   

5.
Nonlinear dynamics analysis of a new autonomous chaotic system   总被引:2,自引:0,他引:2  
In this paper,a new nonlinear autonomous system introduced by Chlouverakis and Sprott is studied further,to present very rich and complex nonlinear dynamical behaviors. Some basic dynamical properties are studied either analytically or nu-merically,such as Poincaré map,Lyapunov exponents and Lyapunov dimension. Based on this flow,a new almost-Hamilton chaotic system with very high Lyapunov dimensions is constructed and investigated. Two new nonlinear autonomous systems can be changed into one another by adding or omitting some constant coefficients.  相似文献   

6.
A new aluminum thin film percolation system, deposited on glass and silicon wafer surfaces by a vapor deposition method, was investigated. By using the expansive and mobile behaviors of the silicone oil, the Al films are quenched gradually by the silicone oil during the deposition process. TheR-I behavior of the film system was studied, and the anomalous conductivity indicated that, at very low current, the hopping and tunneling effects in the films are much stronger than those of the normal film systems. Project supported by NSFC (Grant No. 19874016) and the Special Fund of Zhejiang Provincial Natural Science Foundation for Young Scientists (Grant No. 1997-RC9603).  相似文献   

7.
The Bacillus firmus was immobilized into Ca-alginate beads according to the different initial biomass concentration, calcification time and activation time.Three types of immobilized Bacillus firmus beads were packed respectively in trickling biofilter to purify xylene contained waste gases,and the performance of immobilized-cell biofilter was compared with traditional biofilm attached biofilter packed with two types of ceramic pellets.The results showed that three types of immobilized beads had different capabilities for removing xylene and life-spans.Higher initial biomass in immobilized beads resulted in better performance but shorter life-span.Activation process can remarkably enhance the activity of bacteria,and the removal efficiency of xylene can substantially be improved.Calcification time had influence on life-span of immobilized beads.Without acclimation,the cell-entrapped biofilter can obtain the maximum elimination capacity of 92.4 g/(m~3·h).However,compared with biofilm attached biofilter,it has a poorer intrinsic drawback in volatile organic compounds (VOCs) removal due to the existence of excess mass transfer resistance.  相似文献   

8.
INTRODUCTION To compute the minimum distance between two convex polygons or polyhedrons is often a main step of many applications, such as collision detection (Choi et al., 2006; Li et al., 2003), path planning. In order to reduce the time complexity of the algorithm as much as possible, the convex property must be applied fully. Edelsbrunner (1985) proposed an algorithm for computing the minimum distance between two dis- joint convex polygons. The algorithm takes O(logm logn) time, and …  相似文献   

9.
Feature selection ks a process where a miniraal feature subset ks selected from an original feature set according to a certain measure. In this paper, feature relevancy ks defined by an inconsistency rate. A bidirectional automated branch and bound algorithm is presented. It is a new complete search algorithm for feature selection, which performs feature deletion and feature addition in parallel.Its bound ks determined by inconsistency rate of the original feature set, hence termed as ‘automated‘. Experimental study shows that it ks fit for feature selection.  相似文献   

10.
A judgment criterion to guarantee a point to be a Chen's approximate zero of Newton method for solving nonlinear equation is sought by dominating sequence techniques. The criterion is based on the fact that the dominating function may have only one simple positive zero; assuming that the operator is weak Lipschitz continuous, which is much more relaxed and can be checked much more easily than Lipschitz continuous in practice. It is demonstrated that a Chen's approximate zero may not be a Smale's approximate zero. The error estimate obtained indicated the convergent order when we use |f(x)|<ε to stop computation in software. The result can also be applied for solving partial derivative and integration equations. Project supported by the Special Funds for Major State Basic Research (973) Program(No. 19990328) and the National Natural Science Foundation of China(No. 10271112), and Y. C. Tang Disciplinary Development Fund of Zhejiang University, China  相似文献   

11.
Unbalanced vibration in dual-rotor rotating machinery was studied with numerical simulations and experiments. A new method is proposed to separate vibration signals of inner and outer rotors for a system with very little difference in rotating speeds. Magnitudes and phase values of unbalance defects can be obtained directly by sampling the vibration signal synchronized with reference signal. The balancing process is completed by the reciprocity influence coefficients of inner and outer rotors method. Results showed the advantage of such method for a dual-rotor system as compared with conventional balancing. Project supported by the National Natural Science Foundation of China (No. 59875078), and Zhejiang Provincial Natural Science Foundation of China (No. 502092)  相似文献   

12.
In this paper we discuss a novel storage scheme for simultaneous memory access in parallel turbo decoder. The new scheme employs vertex coloring in graph theory. Compared to a similar method that also uses unnatural order in storage, our scheme requires 25 more memory blocks but allows a simpler configuration for variable sizes of code lengths that can be implemented on-chip. Experiment shows that for a moderate to high decoding throughput (40-100 Mbps), the hardware cost is still affordable for 3GPP's (3rd generation partnership project) interleaver.  相似文献   

13.
Multiresolution image fusion scheme based on fuzzy region feature   总被引:1,自引:0,他引:1  
INTRODUCTION Image fusion can be defined as the process by which several images, or some of their features, are combined together to form different modalities or instruments, and is of great importance in many ap- plications (Hall and Llinas, 1997; Zhou et al., 1998), such as object detection, ATR (Automatic Target Recognition), remote sensing, computer vision, and robotics. Recently some researchers recognized that it seems more meaningful to combine objects/regions rather than pixels…  相似文献   

14.
In an object-based storage system, a novel scheme named EAP (extending attributes page) is presented to enhance the metadata reliability of the system by adding the user object file information attributes page for each user object and storing the file-related attributes of each user object in object-based storage devices. The EAP scheme requires no additional hardware equipments compared to a general method which uses backup metadata servers to improve the metadata reliability. Leveraging a Markov chain, this paper compares the metadata reliability of the system using the EAP scheme with that using only metadata servers to offer the file metadata service. Our results demonstrate that the EAP scheme can dramatically enhance the reliability of storage system metadata.  相似文献   

15.
The main principle and the characteristic of Predictive Functional Control (PFC) strategy are presented in this paper and the corresponding control system aid design software APC-PFC is also introduced. For a chlorinated polyethylene (CPE) process, a design scheme of cascade predictive functional control system is described and the control performance is improved obviously. Project (No. 69974035) supported by the National Natural Science Foundation of China  相似文献   

16.
INTRODUCTION Many people paid attention to passive theory and used it to control chaotic dynamical systems (Byrnes and Isidori, 1991; Yu, 1999). Yu (1999) studied the passive equivalence of the Lorenz chaotic system and presented the method of passive control of chaotic system. Using passive theory, Qi and Zhao (2005) researched on the control of Permanent Magnet Synchronous Motor chaotic system, and stabilized the system at different equilibrium points. However, in order to design th…  相似文献   

17.
A new kind of fuzzy control scheme, based on the identification of the signal's main frequency and the behavior of the ER damper, is proposed to control the semi-active suspension system. This method adjusts the fuzzy controller to achieve the best isolation effect by analyzing the main frequency's characters and inspecting the change of system parameters. The input of the fuzzy controller is the main frequency and the optimal damping ratio is the output. Simulation results indicated that the proposed control method is very effective in isolating the vibration. Project (No. 69974024) supported by the National Natural Science Foundation of China  相似文献   

18.
Abstract A new function-valued partial Padé-type approximation was introduced in the polynomial space, and an explicit determinant formula was derived by means of some orthogonal polynomials. This method can be applied to estimating surplus eigenvalues of the Fredholm integral equation of the second kind when its partial eigenvalues have been known, and at the same time, it can be applied to solving the approximating solution of the given equation.  相似文献   

19.
In the light of Ф-mapping method and the relationship between entropy and the Euler characteristic, the intrinsic topological structure of entropy of Kerr black holes is studied. From the Ganss-Bonnet-Chem theorem, it is shown that the entropy of Kerr black hole is determined by singularities of the Killing vector field of spacetime. These singularities naturally carry topological numbers, Hopf indices and Brouwer degrees, which can also be viewed as topological quantization of entropy of Kerr black holes. Specific results S = A/4 for non-extreme Kerr black holes and S = 0 for extreme ones are calculated independently by using the above-mentioned methods.  相似文献   

20.
The virtual laminated element method (VLEM) can resolve structural shape optimization problems with a new method. According to the characteristics of VLEM, only some characterized layer thickness values need be defined as design variables instead of boundary node coordinates or some other parameters determining the system boundary. One of the important features of this method is that it is not necessary to regenerate the FE (finite element) grid during the optimization process so as to avoid optimization failures resulting from some distortion grid elements. The thickness distribution in thin plate optimization problems in other studies before is of stepped shape. However, in this paper, a continuous thickness distribution can be obtained after optimization using VLEM, and is more reasonable. Furthermore, an approximate reanalysis method named “behavior model technique” can be used to reduce the amount of structural reanalysis. Some typical examples are offered to prove the effectiveness and practicality of the proposed method. Project (No. 50075083) supported by National Natural Science Foundation of China  相似文献   

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