基于最大维密度的全局优化空间聚类算法

在优化空间聚类算法的研究中,传统的K-means空间算法存在两个缺陷,其一是对空间对象的属性描述不全面,其二是对初始种子集选取敏感,容易陷入局部最优值,聚类结果不稳定。为了优化算法,引入适合空间对象的空间属性距离和基于最大维密度选择方案(Max-Dimension of Density Based Seeking,MDDBS)来改进K-means算法,提出利用最大维密度的全局优化空间聚类算法(Max-Dimension of Density Based Clustering,MDDBC),可从密度大的区域选取初始种子,同时又尽量将种子分散在数据空间。实验结果表明,改进方法可以很好消除聚类结果的波动性,同时更加客观地呈现空间对象的分布规律。

一般线性李超代数■(1,n)的交换子代数的最大维数

1905年,I.Schur提出特征零代数闭域上的一般线性李代数■m()的交换子代数的最大维数,进而可以确定任一有限维交换的李代数的忠实表示的最小维数。然而,特征为0的代数闭域上的有限维交换李超代数的极小忠实表示仍是一个公开的问题。基于两两交换的矩阵可以同时上三角的事实,利用矩阵的相似变换,确定特征0代数闭域上一般线性李超代数■(1,n)的不可分解的交换子代数的最大维数。

n阶可换矩阵空间的最大维数

本文研究了一类重要的矩阵空间，即Ｍｎ（Ｃ）的ｎ阶可换矩阵空间，得出了一个重要结论：ｎ阶可换矩阵空间的最大维数至少应为ｎ，并对ｎ＝２，３，４的情形，具体计算出了这个最大维数．

N阶可换矩阵空间的最大维数

本文研究了一类重要的矩阵空间,即n阶可换矩阵空间,得出了一个重要结论:n阶可换矩阵空间的最大维数只能是n。

LOCAL NONLINEAR CHARACTERISTICS OF GAS LIQUID SOLID THREE PHASE SELF ASPIRATED REVERSED FLOW JET LOOP REACTOR

Hursts rescaled range (R/S) analysis and Wolfs attractor reconstruction technique have been adopted to estimate the local fractal dimensions and the local largest Lyapunov exponents in terms of the time series pressure fluctuations obtained from a gas liquid solid three phase self aspirated reversed flow jet loop reactor,respectively.The results indicate that the local fractal dimensions and the local largest Lyapunov exponents in both the jet region and the tubular region inside the draft tube increase with the increase in the jet liquid flowrates and the solid loadings,the local fractal dimension profiles are similar to those of the largest Lyapunov exponent,the local largest lyapunov exponents are positive for all cases,and the flow behavior of such a reactor is chaotic.The local nonlinear characteristic parameters such as the local fractal dimension and the local largest Lyapunov exponent could be applied to further study the flow properties such as the flow regime transitions and flow structures of this three phase jet loop reactor.

Numerical study on maximum rebound ratio in blasting wave propagation along radian direction normal to joints

In the process of 2-D compressional wave propagation in a rock mass with multiple parallel joints along the radian direction normal to the joints, the maximum possible wave amplitude corresponding to the points between the two adjacent joints in the joint set is controlled by superposition of the multiple transmitted and the reflected waves, measured by the maximum rebound ratio. Parametric studies on the maximum rebound ratio along the radian direction normal to the joints were performed in universal distinct element code. The results show that the maximum rebound ratio is influenced by three factors, i.e., the normalized normal stiffness of joints, the ratio of joint spacing to wavelength and the joint from which the wave rebounds. The relationship between the maximum rebound ratio and the influence factors is generalized into five charts. Those charts can be used as the prediction model for estimating the maximum rebound ratio.

Quantum Generalized Measurement and Deterministic Generation of Maximum Entangled Pure State

We propose the concept of the quantum generalized projector measurement （QGPM） for finite-dimensional quantum systems by studying the quantum generalized measurement. This research reveals a distinguished property of this quantum generalized measurement： no matter what the system state is prior to the measurement and what the result of the measurement occurs, the state of the system after the measurement can be collapsed into any specified pure state, i.e., the state of quantum system can be deterministically reduced to any specified pure state just by a single QGPM. Subsequently. QGPM can be used to deterministically generate the maximum entangled pure state for quantum systems. We give three concrete theoretic schemes of generating the maximum quantum entangled pure states for two 2-Jevel particles, three 2-level particles and two 3-Jevel particles, respectively.

Construction of a Butterfly Web Bridge

A new type of bridge called ＂butterfly web bridge＂ is under construction in Japan. In a butterfly web bridge, the butterfly-shaped web forms a structure that exhibits behavior similar to a double Warren truss. The 80 MPa concrete is used for the butterfly web which has a precast plate with a thickness of 150 mm. As butterfly web is a concrete material, reinforcement provided by prestressing tendons is needed on the tension side. Moreover, the 150 mm plate has no re-bars but is reinforced by steel fibers. This bridge, named Takubogawa Bridge, is a highway bridge and has 10 spans including the 87.5 m maximum span length. Takubogawa Bridge is constructed by flee cantilevering method. The butterfly web enables the construction speed of cantilevering to be advanced about 50% compared with conventional cast-in-situ method and can meet the requirement of light weight and low maintenance.

Performance Analysis of Medium Access Control Protocol for IEEE 802.11g-over-Fiber Networks

This paper investigates the Medium Access Control(MAC)protocol performance in the IEEE 802.11g-over-fiber network for different payloads and fiber lengths using Direct Sequence Spread Spectrum-Orthogonal Frequency Division Multiplexing(DSSSOFDM)and Extended Rate PhysicalsOrthogonal Frequency Division Multiplexing(ERP-OFDM)physical layers using basic access mode,Request to Send/Clear to Send(RTS/CTS)and CTS-to-self mechanisms.The results show that IEEE 802.11g-over-fiber network employing the ERP-OFDM physical layer is much more efficient than that employing the DSSS-OFDM physical layer,with regards to both throughput and delay.For a given maximum throughput/minimum delay,the tradeoff among the access mechanism,the fiber length,and the payload size must be considered.Our quantified results give a selection basis for the operators to quickly select suitable IEEE 802.11g physical layers and the different access mechanisms,and accurately predict the data throughput and delay given the specific parameters.

Determination of pile failure mechanism under pullout test in loose sand

Estimating the deformation of soil around the pile contributes to reliable design of structures under pullout force. This work presents the results of a series of small-scale physical modelling tests designed to investigate the uplift resistance of piles with diameter of 5 cm and slenderness ratios of 1, 2, 3 and 4 in loose sand. Close photogrammetric technique and particle image velocimetry(PIV) were employed to observe the failure patterns due to uplift force on piles. The results show that the shear zones curve slightly outward near the ground surface. After peak resistance, the shear strain concentrates into a pair of narrow shear bands,then a flow around mechanism is formed accompanied by a reduction in the uplift resistance. The results from the laboratory tests were verified by analytical method proposed by Chattopadhyay and PLAXIS 2D and 3D finite element method software. It is found that the depth and width of the failure surface increase with the increment of the slenderness ratio. A good agreement is observed among the measured bearing capacity and obtained failure surface of the models and the results of numerical modelling. Finally, the maximum deformation of loose and dense sand respectively with densities of 25% and 75% were compared in the stage of fully removing pile. The results shows that the deformation of the soil is related to its density, therefore it depends on its dilatancy.

2D spiral pattern recognition based on neural network covering algorithm

The main aim for a 2D spiral recognition algorithm is to learn to discriminate between data distributed on two distinct strands in the x-y plane.This problem is of critical importance since it incorporates temporal characteristics often found in real-time applications.Previous work with this benchmark has witnessed poor results with statistical methods such as discriminant analysis and tedious procedures for better results with neural networks.This paper presents a max-density covering learning algorithm based on constructive neural networks which is efficient in terms of the recognition rate and the speed of recognition.The results show that it is possible to solve the spiral problem instantaneously(up to 100% correct classification on the test set).

3-D direct current resistivity forward modeling by adaptive multigrid finite element method

Based on the fact that 3-D model discretization by artificial could not always be successfully implemented especially for large-scaled problems when high accuracy and efficiency were required, a new adaptive multigrid finite element method was proposed. In this algorithm, a-posteriori error estimator was employed to generate adaptively refined mesh on a given initial mesh. On these iterative meshes, V-cycle based multigrid method was adopted to fast solve each linear equation with each initial iterative term interpolated from last mesh. With this error estimator, the unknowns were nearly optimally distributed on the final mesh which guaranteed the accuracy. The numerical results show that the multigrid solver is faster and more stable compared with ICCG solver. Meanwhile, the numerical results obtained from the final model discretization approximate the analytical solutions with maximal relative errors less than 1%, which remarkably validates this algorithm.

A maximum a posteriori super resolution algorithm based on multidimensional Lorentzian distribution

This paper presents a threshold-free maximum a posteriori (MAP) super resolution (SR) algorithm to reconstruct high resolution (HR) images with sharp edges. The joint distribution of directional edge images is modeled as a multidimensional Lorentzian (MDL) function and regarded as a new image prior. This model makes full use of gradient information to restrict the solution space and yields an edge-preserving SR algorithm. The Lorentzian parameters in the cost function are replaced with a tunable variable, and graduated nonconvexity (GNC) optimization is used to guarantee that the proposed multidimensional Lorentzian SR (MDLSR) algorithm converges to the global minimum. Simulation results show the effectiveness of the MDLSR algorithm as well as its superiority over conventional SR methods.

Dynamical cavitation and oscillation of an anisotropic incompressible hyper-elastic sphere

Dynamical cavitation and oscillation of an anisotropic two-family fiber-reinforced incompressible hyper-elastic sphere subjected to a suddenly applied constant boundary dead load are examined within the framework of finite elasto-dynamics.An exact differential equation between the radius of the cavity and the applied load is obtained.The curves for the variation of the maximum radius of the cavity with the load and the phase diagrams are obtained by vibration theories and numerical computation.It is shown that there exists a critical value for the applied load.When the applied load is larger than the critical value,a spherical cavity will suddenly form at the center of the sphere.It is proved that the evolution of the cavity radius with time follows that of nonlinear periodic oscillation,and oscillation of the anisotropic sphere is not the same as that of the isotropic sphere.