Along with the development of Internet/Intranet application, more and more sensitive data is transmitted through the network. In order to prevent the critical data from being divulged and guarantee the security of information, we should pay more attention to the surveillance of network traffic. With this motivation, we present an efficient TCP flow reassembling algorithm which is the key of dataflow processing. Through this method, it is possible to get a whole idea of every TCP flow and providing a good reference to judgment. Testing of a prototype based on PF_RING demonstrated that our mechanism take a good performance in linux kernel 2.6.28.
This paper focuses on the absolute stability of a new class of Takagi-Sugeno (T-S) fuzzy Lurie control systems with Time-varying Delay. By utilizing the Lyapunov-Krasovskii functional (LKF) and novel techniques, new Lyapunov functions are defined and a new absolute stability condition is derived in the form of Linear matrix inequalities (LMIs) which is different from existing ones.
In this paper, we develop a distributed cooperative spectrum sensing algorithm based on network code to decrease the need for bandwidth in cognitive radios. The model of the distributed cooperative spectrum sensing is analyzed, and the algorithm of distributed scheme based on network code is described. The simulation results show that compared with the distributed scheme without network code and the non-cooperative one, the throughput of secondary users is increased apparently, and also, the probability of detection of the distributed scheme with network code is improved about 10% and 20%, respectively, further, the optimal sensing time is shorter about 82% and 88%, respectively.
Searching and managing information are becoming increasingly important for large distributed storage systems. This paper presents a metadata management mechanism named CBMM, which is based on the Chord protocol to organize the metadata server cluster. Utilizing the advantages of Chord protocol for distributing metadata across a cluster of metadata servers can highly improve the throughput, balance metadata distribution, and afford dynamic scalability of metadata servers.
This paper proposes out a variation of particle swarm optimization with best neighbor and worst particle (BNWPPSO). In BNWPPSO, some particles will be constructed as new neighbors of each particle and the best one of them will have influence on the behavior of the particle. The update formula of position is modified also to balance the local search ability and global search ability more efficiency. The worst particle of the swarm will be re-randomized at every generation to prevent premature convergence of PSO. BNWPPSO is investigated by several benchmark problems, the results show that BNWPPSO performances better than traditional PSO. Furthermore, BNWPPSO is applied to train artificial neural network to construct a soft-sensor of gasoline endpoint of crude distillation unit. The results show that the model constructed by BNWPPSO is feasible and effective.
Aiming at the limited resources and data transmission redundancy of WSN, this paper proposes a novel data compression algorithm based on lifting wavelet transform, gives the rational design. The algorithm distributes the computing quantity which the lifting wavelet transform requires to all nodes, eliminates extra computing and data transmission, reduces the information redundancy of network, greatly saves the energy of wireless transmission, prolongs network lifetime. The simulation results show that the data compression algorithm based on lifting wavelet transform performs well in energy saving without sacrificing the reconstruction quality of signal in comparing with the data compression algorithm based on traditional wavelet transform.
To forecast the thermal response of LPG ( liquefied petroleum gas ) storage tank under the conditions of a non-normal thermal environment is of great practical significance to the evaluation of gas storage and transportation security, especially on disastrous accident prediction. This paper is based on the relationship between conservation of mass and energy conservation to describe the physical model and mathematical model of tank of LPG storage tank thermal response under high-temperature environment. And to have the theoretical analysis on the process from the high temperature environment to the internal heat transfer medium and the confirmation of the system pressure, and use the finite difference method to solve the mathematical model for thermal response of the liquefied gas storage tank, and found the rule of change of the pressure, temperature, density and quality under liquid region and the gas zone. The Object-oriented, visualization of visual c++ software was used to develop the numerical simulation software of the liquefied gas storage tank thermal response under the environment of high-temperature. This software is used to calculate the numerical value of the thermal response and the curve simulation of liquefied petroleum gas storage tank under the different flame environment, the different shape of the container, and the filling of the volume of different media etc.
The topology mismatching is one of major factors that cause the low efficiency in P2P system and the consumption of large quantity of network bandwidth, while peer aggregation is a kind of practical way to make topology matching. This paper firstly introduces a multilevel marked system. According to the marked symbol, peers can progressively find theirs neighbor peers in a better way to achieve the goal of aggregation. Then we build a simulation environment to analyze its performance, the experimental results show that this method can implement peer aggregation rapidly and well adapt to the turbulence caused by peer failure.
Authenticated group key exchange (AGKE) enable a set of participants in a public network to share a key which can be further used to achieve confidentiality and authe.ntication. Most of the schemes required a linear number of communications round with respect to the number of group members, such schemes are not practical. Others are inefficient being required some additional condition such as central authority or logic structure. After analyzed the security of Bresson's protocol, a improved scheme is proposed, which is simple and efficient. The scheme is proven secure under Decisional Diffie-Hellman assumption.
There are many methods for image fusion now. However, Multi-wavelet is attached importance to its superiority on theory and its potential on applications. Lifting scheme is not only a fast algorithm of existing wavelet transforms, but also a tool to produce new wavelet transforms. According to the characteristic of the lifting scheme and multi-wavelet transform, a new lifting scheme for multi-wavelet transforms was presented in this paper, and it was applied to image fusion. Better results were achieved.
We investigate the problem of family energy consumption in the process of replacing landline phones with cell phones. We found that cell phones consume much less energy than landline phones. We adopted U.S as our study samples. We applied Gompertz function to predict the cell phone diffusion trend in the U.S and hence simulate energy consumption by family phones during this process. Our results indicate that the transition stage will end at 2011, while energy consumption by phones declines monotonously during this period.
This text analyzed the reason of generating error of GM (1, 1), from the integral calculus angle discrete GM (1, 1). A kind of method putting forward making use of Romberg integral calculus formula and quadratic interpolation method to construct the background value of the model, raised simulation and prediction precision of GM(1,1), and the actual example verify the feasibility and effectiveness of this method.
The developing grid techniques provide feasible realization schemes for the fast and accurate computing of electromagnetic scattering fields in complex environments. This paper presents the research on the parallel computing of electromagnetic scattering fields in complex environments using MLFMA and IE-ODDM. This parallel computing is based on CGSP, which can provide feasible schemes for solving the accurate computing problems of electromagnetic scattering fields in great complex environments.
With the enlargement of sizes of networks, scale-free property of networks is present. However, scale-free networks are fragile. If the nodes with most degree are attacked, the whole network will be devastated. This paper proposed an algorithm to optimize the topology of scale-free networks with redundant edges. Adjacent networks of key nodes will be linked as a rotary and junction structure, to ensure the communication between remaining nodes when critical nodes are attacked. A simulation was carried out to prove that the resilience of scale-free network to removal of key nodes could be enhanced using the proposed algorithm.
At present, the research of biometric recognition is gave more and more attention in the world. The iris recognition is a kind of the biometrics technologies based on the physiological characteristics of human body, compared with the feature recognition based on the fingerprint, palm-print, face and sound etc. the iris recognition technology has recently become popular in identity recognition. In my paper, based on the existing iris location algorithm, an improved iris location algorithm is brought forward. This method can achieve a precise and rapid iris location. In this method, inner circle positioning algorithm is improved by the changed Ostu adaptive binarization thresholding algorithm and the changed gray-scale projection method. And external positioning is completed by Roberts operator.
Recently, Khan et al. proposed an efficient and practical chaotic hash-based fingerprint biometric remote user authentication scheme on mobile devices. Unfortunately, Yoon-Yoo demonstrated that Khan et al.'s scheme was vulnerable to a privileged insider attack and an impersonation attack by using lost or stolen mobile devices. To isolate such problems, Yoon-Yoo proposed an improvement to Khan et al.'s scheme. However, the two authentication schemes required synchronized clocks between the user and the remote system server because of using timestamps in authentication process. Actually, it is fairly complicated to achieve time concurrency mechanism; and network environment and transmission delay is unpredictable, so some drawbacks exist in their scheme. To overcome those weaknesses, a new fingerprint-based remote user authentication scheme using mobile devices is proposed. The proposed scheme can safely achieve mutual authentication between the users and the remote system. Compared with other related schemes, the proposed scheme not only is secure and efficient but also can provide good characteristics. Hence, our proposed scheme can be easily realized in the practical environment.
A novel chemical micro-gas sensor array composed of polyaniline (PANI) and its nanocomposite thin film was fabricated for NH3, CO and H2 gas classification. Itanium dioxide (TiO2), indium oxide (In2O3) and multi-walled carbon nanotube (PANI/MWNT) combined with PANI were chosen as the sensing materials by the step-clustering analysis. The normalization method was developed to eliminate the dispersion of the array data. Probabilistic neuron network (PNN) was designed and trained with the processed data, and the different discrimination results were discussed under the different spread constant (SP). The accurate classification result was achieved when SP was set as 0.05 or 0.1.
In this paper, solvent-functionalized CNTs are coated on mass-sensitive quartz crystal microbalance (QCM) devices to study their gas-sensing properties for volatile organic compounds (VOCs) at room temperature. The results indicate that different solvent-functionalized CNTs under the same conditions have the dissimilar response and similar VOCs to the polarity of the solvent show better gas-sensing properties such as high sensitivity, good repeatability and reversibility. This has a certain significance to improve the selectivity of CNT based sensors.
A speed control approach with grey control theory is proposed based on the state-space model of the star-connected three-phase brushless DC motor in line-voltage mode. The algorithm of the grey predictor is given. Double-loop PI controllers and the GM (1, 2) are used to compensate the disturbance from the load and internal parameters of the motor, while the uncertainty part is considered as a grey system. To assure the system responds to the newest behavior in time, the initial discrete state sequence in GM (1, 2) model is established by the equal dimension and new information method. The simulation results have shown that the GM (1, 2) predictor can reduce the disturbance in the speed and current loops, and proved the effectiveness and good anti-disturbance ability of the proposed control method.
