We obtained a real irreducible representation of SU(2) into G₂ from the standard irreducible unitary representation of SU(2) and studied different SU(2)-orbit types in a six-sphere, especially the CR-orbits.

We consider a Markov process on a connected graph, where each edge is labeled with the transition rate between the two adjacent vertices. The fastest mixing Markov process (FMMP) problem is the problem of assigning transition rates to the edges so as to maximize the second smallest eigenvalue λ₂ of the Laplacian of the weighted graph, which determines the mixing rate of the Markov process. We show that the FMMP problem always attains its optimum in the fixed-point subset of the feasible set under the automorphism group. This result can be used to reduce the number of optimization variables on graphs with symmetries. We analytically find the optimal solutions on edge-transitive graphs.

Dynamical model of open quantum systems in a matrix form is transformed into the model in a vector form using Liouville super-operator. Given a dynamical model of a dissipative quantum system in the presence of a time-dependent external control field, we achieve an improved optimal control law with the squared error between density matrices of system state and target state as the performance index. The states transfer experiment on a spin 1/2 particle system is carried out. Under the proposed optimal control, eigenstates, pure states, and mixed states are taken as initial and target states of the system, respectively. Detailed comparative analyses are given.

We design a substrate-heat pipe cooling system for a high-power 80 W LED in a large space with natural convection. Effects of LED input power and heat sink tilt angle on LED junction temperature and luminance are studied. The experimental results show that this heat pipe cooling system can reduce the LED junction temperature to 73.5 ℃. The results also indicate that LED input power and heat sink tilt angle have strong effects on LED junction temperature and luminance.

The β-CD-grafted-chitosan (CDCS) has been synthesized with chitosan as matrix. The structure of the product has been determined and characterized by FT-IR, XRD, and H₂SO₄ degradation methods. Further more, the host-guest interaction of CDCS with ferrocene and ferrocenylcarbonyl benzoic acid has been systematically studied by employing XRD and UV techniques. As expected, the guest compounds containing ferrocene interact with the β-CD-labeled polymer backbone.

A partial nitrification-ANAMMOX reactor system for domestic wastewater was set up, and the composition of N-related functional bacteria in the activated sludge were studied. During the stable period, the TN removal rate reached to about 80%. In the partial nitrification system, the dominant AOB is Nitrosomonas europaea/Nitrosococcus mobilis cluster-like bacteria, and the dominant NOB are Nitrobacter vulgaris-like bacteria and Nitrospira defluvii-like bacteria. In the anammox reactor, Kuenenia stuttgartiensis-like bacteria is the dominant anammox bacteria. Numerous members of proteobacteria, Chloroflexi, and Bacteroidetes/Chlorobi phylum are found to co-exist with anammox bacteria.

We explain the concept of urban land use intensity in four aspects:land use intensity, output efficiency, eco-efficiency, and sustainable use. We build the urban land use intensity evaluation index system which can be used for oasis cities along the railway line in the north of Xinjiang. Simultaneously we discuss the spatial variation of the results using the GIS spatial analyzed methods and techniques, and analyze the reasons.

We propose a method for comprehensive evaluation of the spatial heterogeneity in farmland shelterbelt networks. Using this method, we evaluated the dynamic changes in spatial heterogeneity in shelterbelt networks in the midwest of Jilin province from 1987 to 2008. The results show that the regions with rationally distributed shelterbelt networks accounted for 20.84% of the total farmland area in 2008, but the proportion was only 0.21% in 1987. However, the spatial layout of shelterbelts is still unreasonable. Therefore, it is necessary to make strenuous efforts to update and construct the farmland shelterbelts in the studied area.

Model selection plays an important role in support of vector machine classification. We propose a concept of kernel prototype which means general kernel type. Based on this, a new algorithm for model selection for supporting vector machine classification is proposed. The powerful adaptive genetic algorithm is used to optimize the parameters in kernel prototype, and it can find the optimal kernel type as well as the kernel parameters. Experiments show effectiveness and stability of the algorithms.

The parametric matched filter (PMF) and the vector autoregressive (VAR) temporally-whitening filter are analyzed. The results show that the coefficients of the PMF obtained by minimizing mean square error (MSE) estimated via sum of squared errors (SSE) are equivalent to those of the VAR filter by multichannel least square (LS) algorithm of the same order. Additionally, the asymptotic performance of the LS estimator of VAR filter is analyzed. Finally, the operations and performances for clutter suppression are analyzed.

An explicit method for adjusting the sending window using the number of TCP flows at the destination satellite and the number of satellites in the path is proposed. With this method, different reactions to packet-droppings are executed for different-delay flows. The simulation results using NS2 show that the performances and fairness of different-delay TCP flows are enhanced distinctly, the packet-droppings are decreased, and the bandwidth utilization of the downlinks of the destination satellite is increased effectively while dealing with channel drops.

Development of the geometrical identification method of blocks in fractured rock masses is divided into three stages and the representative research results in each of the stages are analyzed. We compare and analyze the typical three-dimensional whole space block identification methods and give a general mathematical description for these methods. The existing problems and topics which need further research are pointed out.

An analytical framework is proposed to analyze the effect of feedback error and the closed-form SNR expression is derived. Based on the closed-form expression, the power allocation between the feedback and data transmission stages is given to maximize the achievable rate upper bound. Simulation results show that the achievable rate can be effectively improved by the proposed power allocation and the relay number is limited with noisy limited feedback.

Load balancing is one of the most important technical methods for improving the overall performance of clustered databases. On the basis of comparisons of several present load balancing methods, we present a multi-criteria dynamic load balancing method.The method was designed to collect load state at all the backends of the cluster, make an ordered sequence of the backends using TOPSIS multi-criteria decision method, and send the request to the backend supposed to be the lightest in burden. On the basis of the experimental results we come to the conclusion that the method does improve the performance of the clustered database system compared to traditional load balancing methods.

Data need to be replicated because of performance and availability in the cluster system composed of heterogeneous database, and data replication between different databases is an important issue to be solved. A new method for the heterogeneous data replication is described on the basis of the database replication technology. Since most of the existing solutions are dependent on the specific DBMS, a new fully heterogeneous data replication method is proposed and it uses common database interface and data structure to achieve the DBMS independence. Application of the method to the database cluster for data replication between backend data nodes improves the availability and scalability of the system.

We propose an algorithm which combines parameterized constraints and trust worthiness. Simulation results show that the algorithm can effectively shield the requests from the undesirable entities, achieving the fine grit authorization in a rather flexible way. Simultaneously, this algorithm enhances the computing efficiency and reduces the space for building the credential chains.

We propose a new steganalysis approach against MP3Stego based on Huffman table distribution and recoding scheme. Huffman table distribution features are used to detect uneven quantization among blocks. Recoding scheme can be used to calibrate cover signals and to reduce the variety caused by different carriers. Experiments show that our method is successful in detecting MP3Stego even at a very low embedding rate.

Loiss is a byte-oriented stream cipher. It generates keystream bytes under control of both initial key and IV. We analyze Loiss’ security in resistance to guess-and-determine attack. Without guessing the register cells of BOMM structure in Loiss, we give an attack method with time complexity O(2²⁴⁷) and data complexity O(2⁵²).

Considering that most objects in worm simulation based on GTNetS are small objects, we carry out a study on the memory management of the GTNetS and propose the small object memory allocation technique. The experimental results show that the small object memory allocation technique can significantly reduce the peak memory usage in worm simulation and hence improves the simulation scalability and efficiency.

For practical SAR systems, the motion errors of radar platform lead to the azimuth phase history errors which lead to defocus images. We propose a modified autofocus method which applies the delay and remove algorithm for more effectively estimating the real phase history based on azimuth data. With this method a better focused image is achieved. The algorithm is efficient for real-time SAR system. The focus processing results of SAR measured data show that the proposed method is effective.

Home Node B(HNB) is a key point in the system of wireless communication. We focus on the security of the HNB system, especially the authentication protocol based on certificates. We analyze the disadvantages of the original protocol and propose a new protocol without certificates to simplify the process of mutual authentication. We also give an analysis of the security of the new protocol.