一种基于多模分布的SAR图像分割算法

SAR图像目标、背景、阴影的不同散射机理使得这三部分具有不同的统计特性。分析SAR图像三部分统计性质分别建立统计模型,并给出了一种基于这三种模型组合的多模分布的SAR图像分割算法,对于目标分割和阴影分割分别采用不同的预处理方法,分别提出了快速Otsu分割算法分割目标和基于背景均值保留的冲击滤波算法分割阴影。分割结果表明,这种基于多模分布的SAR图像分割算法与传统的基于单模分割算法相比,能最佳地利用各部分统计特性的差异,得到准确的分割结果。

共平台的多模基站分布系统研究

文章阐述了多模远端分布系统的用途、功能、特性和组网方式,并针对采用多模远端分布系统需满足"三网合一"的标准要求,详细分析了GSM、TD-SCDMA和WLAN的多模基站分布系统,提出了科学新颖的共平台多模远端基站分布系统方案。

单元件干涉数字全息的光线追迹模型

基于棱镜对的单元件干涉可以获得透射物体的相位信息,即数字全息,具有结构紧凑、干涉条纹稳定、测量精度高等优点。采用光线追迹方法,综合考虑了棱镜对的方位角旋转、斜面偏心等参数,建立了光线追迹等效模型,仿真了数字全息干涉条纹,给出了条纹密度变化及倾斜的解析表达式。针对单模和多模光纤等微结构光学元件,获得了干涉数字全息图,并反演出其折射率分布。搭建了显微成像单元件干涉实验装置,获得了实际测量干涉图样,实验与仿真结果一致,证明了本模型的有效性。

提高雷达HRRP目标识别和拒判性能的核学习算法

雷达高分辨距离像（HRRP）数据具有明显的多模分布特性．在雷达HRRP识别和拒判中，采用单个高斯核很难准确地描述HRRP数据的多模分布．针对该问题，将单个高斯核扩展到多个高斯核线性组合的形式，并将该组合形式应用到支持向量域描述（sVDD）中来处理识别和拒判问题,根据对组合系数自由度的不同限制，扩展后的多核支持向量域描述（Multi-kernel SVDD）方法可以分别表述为不同的凸优化形式：二阶锥规划（SOCP）和半正定规划（sDP），它们都可以收敛到全局最优解．新方法采用了更加复杂的核函数形式，能够更加灵活地描述HRRP数据在高维特征空间的多模分布，从而提高雷达HRRP的识别和拒判性能．仿真实验结果显示该方法的损失值仅为单核SVDD的88．6％～93．2％．

MULTI-AGENT BASED DISTRIBUTED MANUFACTURING EXECUTION SYSTEM MODEL

A multi-agent based manufacturing execution system (MES) model is presented. It is open, modula-rized, distributed, configurable, integratable and maintainable. By analyzing the MES domain in manufacturing systems, this paper proposes a multi-agent based MES model and analyzes the partitioned functions of MES in the model using unified modeling language (UML) diagrams, and establishes the ongoing implemented MES architecture. This MES can be facilely integrated with the enterprise resource planning (ERP), the floor control system (FCS), and the other manufacturing applications.

Relationship between Abundance and Area of Pinus tabulaeformis and Quercus liaotungensis Koidz in Lingkong Mountain Nature Reserve

The spatial distribution and species abundance of Pinus tabulaeformis and Quercus liaotungensis Koidz were analyzed with random distribution abundance model and aggregated distribution abundance model,and evaluation goodness was evaluated based on related information of sample area at 4 hm2 in Shanxi Lingkong Mountain with altitude at 1500-1 800 m.The results showed that of the 30 xylophyta plants,abundance of 20 plants was increasing in sequence and the covered spaces extended accordingly,except of 10 plant species.As pixel area extended,curve of abundance-area tended to be volatile if area in abundance sequence was smaller than that of the front one;the curve tended to be stable if the fluctuating point was removed.For the same species,the higher pixel area is,the larger the covered area of the species in corresponding pixel would be.The results of evaluation goodness indicated that aggregated distribution model is better for prediction on relationship between abundance and area,compared with random distribution abundance model.Both of the two models rely on value of m,namely,number of covered pixel given the pixel is fixed.For the species distribute dispersedly,the prediction results would be more accurate if both of the two models are made use of,or the prediction errors would be larger.Given that the total area of sample plot is fixed,the smaller the pixel area is,the more accurate the prediction would be.

Structural behaviors of steel roof truss exposed to pool fire

Experimental research was conducted to study the structural behaviors of a steel roof truss model without fire-proof coating under pool fire conditions. The data of temperature distribution and displacements of typical members were obtained. It is found that the temperature distribution of environment inside the structure, which is found to be in accordance with the multi-zone model with height, has a decisive effect on the tempera^tre evolution of steel members. Besides, it can also be observed that due to the restriction and coordination among the truss members in the localized fire, the maximum relative deflection, which occurs at the mid-span of the top chord, is relatively slight and has not exceeded 1 mm under experimental conditions. On the other hand, the column experiences a notable thermal expansion during the test. Then, a finite element model is presented and validated by the test results.

Computer aided modeling and pore distribution of bionic porous bone structure

Artificial bone with porous structure is crucial for tissue scaffold and clinic implants.Scaffold provides structure support for cells and guides tissues regeneration for final tissue structure.A computational aided process of porous bone modeling was developed which described the design and fabrication of tissue scaffolds by considering intricate architecture,porosity and pore size.To simulate intricate bone structure,different constructive units were presented.In modeling process,bone contour was gotten from computed tomography(CT)images and was divided into two levels.Each level was represented by relatively reconstructive process.Pore size distribution was controlled by using mesh generation.The whole hexahedral mesh was reduced by unit structure,when a 3D mesh with various hexahedral elements was provided.The simulation results show that constructive structure of porous scaffold can meet the needs of clinic implants in accurate and controlled way.

Coordinated scheduling model for intermodal transit hubs based on GI/M^K/1 queuing system

Coordinated scheduling of multimode plays a pivotal role in the rapid gathering and dissipating of passengers in transport hubs. Based on the survey data, the whole-day reaching time distribution at transfer points of passengers from the dominant mode to the connecting mode was achieved. A GI/M K/1 bulk service queuing system was constituted by putting the passengers' reaching time distribution as the input and the connecting mode as the service institution. Through queuing theory, the relationship between average queuing length under steady-state and headway of the connecting mode was achieved. By putting the minimum total cost of system as optimization objective, the headway as decision variable, a coordinated scheduling model of multimode in intermodal transit hubs was established. At last, a dynamic scheduling strategy was generated to cope with the unexpected changes of the dominant mode. The instance analysis indicates that this model can significantly reduce passengers' queuing time by approximately 17% with no apparently increase in departure frequency, which provides a useful solution for the coordinated scheduling of different transport modes in hubs.

Bayesian Variable Selection via Perfect Gibbs Coupler Using Approximate Bounds

Variable selection is one of the most fundamental problems in regression analysis. By sampling from the posterior distributions of candidate models, Bayesian variable selection via MCMC （Markov chain Monte-Carlo） is effective to overcome the computational burden of all-subset variable selection approaches. However, the convergence of the MCMC is often hard to determine and one is often not sure about if obtained samples are unbiased. This complication has limited the application of Bayesian variable selection in practice. Based on the idea of CFTP （coupling from the past）, perfect sampling schemes have been developed to obtain independent samples from the posterior distribution for a variety of problems. Here the authors propose an efficient and effective perfect sampling algorithm for Bayesian variable selection of linear regression models, which independently and identically sample from the posterior distribution of the model space and can efficiently handle thousands of variables. The effectiveness of the authors＇ algorithm is illustrated by three simulation studies, which have up to thousands of variables, the authors＇ method is further illustrated in SNPs （single nucleotide polymorphisms） association study among RA （rheumatoid arthritis） patients.

Species Abundance Distribution Patterns of a Toona ciliata Community in Xingdoushan Nature Reserve

With the goal of model fitting species abundance distribution patterns of the tree,shrub and herb layers of the natural Toona ciliata community in Xingdoushan Nature Reserve,Enshi Autonomous Prefecture,Hubei Province,we used the data collected from the field survey and employed different ecological niche models.The models tested were the broken stick model(BSM),the overlapping niche model(ONM)and the niche preemption model(NPM),as well as three statistic models,the log-series distribution model(LSD),the log-normal distribution model(LND)and the Weibull distribution model(WDM).To determine the fitted model most suitable to each layer,the fitting effects were judged by criteria of the lowest value of Akaike Information Criterion(AIC),Chi-square and the K-S values with no significant difference(P>0.05)between the theoretical predictions and observed species abundance distribution values.The result showed:(1)The fitting suitability and goodness of fit of the tree,shrub and herb layers by using the three ecological niche models were ranked as:NPM>BSM>ONM.Of the three statistical models,by accepting the fitting results of the three layers,WDM was the best fitting model,followed by LND.By rejecting the fitting tests of the herb layer,LSD had the worst fitting effect.The goodness of the statistical models was ranked as:WDM>LND>LSD.In general,the statistical models had better fitting results than the ecological models.(2)T.ciliata was the dominant species of the tree layer.The species richness and diversity of the herb layer were much higher than those of either the tree layer or the shrub layer.The species richness and diversity of the shrub layer were slightly higher than those of the tree layer.The community evenness accorded to the following order:herb>shrub>tree.Considering the fitting results of the different layers,different ecological niche models or statistical models with optimal goodness of fit and ecological significance can be given priority to in studying the species abundance distribution patterns of T.ciliata communities.

Numerical Simulation for Thermal Distribution of Air-conditioner Outdoor Units

Air-conditioners used in high-rise residential or office buildings often have outdoor units installed on the side-walls or roofs in the confined space of the buildings.The heat released from the outdoor units causes the tem-perature rise in the confined installation space and leads to uncomfortable thermal environment and deteriorative performance of air-conditioners.The factors affecting the performance of air-conditioners are the heat released from the outdoor units,the solar radiation and the ventilation of the confined installation space,which are inves-tigated in this study and simulated by FLUENT using the porous model and discrete ordinates (DO) radiation model.It is proved that the porous model is more reliable than the solid model.The optimal installation distance from the supporting wall is obtained.The average temperature of the exit without wind is 1.18% higher than that with wind.The results show that the heat released from the outdoor units and the ventilation of the confined in-stallation space are the main factors affecting the thermal environment in the confined installation space.The in-fluence of the solar radiation is negligible.

Multi-objective optimization of cooling air distribution of grate cooler with different inlet temperatures by using genetic algorithm

The paper discussed a multi-objective optimization model of the cooling air distribution of a grate cooler according to the analogy

GEOMETRIC METHOD OF SEQUENTIAL ESTIMATION RELATED TO MULTINOMIAL DISTRIBUTION MODELS

In 1980's, differential geometric methods are successfully used to study curved exponential families and normal nonlinear repression models. This paper presents a new geometric structure to study multinomial distributipn models which contain a set of nonlinear parameters. Based on this geometric structure, the authors study several asymptotic properties for sequential estimation. The bias, the variance and the information loss of the sequeatial estimates are given from geometric viewpoint, and a limit theorem connected with the obServed and expected Fisher information is obtained ill terms of curVature measures. The results show that the sequeotial estimation procedure has some better properties which are generally impossible for nonsequeotial estimation procedures.

Multimode Interference Refractive Index Sensor Based on Coreless Fiber

A multimode interference refractive index （KI） sensor based on the coreless fiber was numerically and experimentally demonstrated. Two identical single mode fibers （SMF） are spliced at both ends of a section of the coreless fiber which can he considered as the equivalent weakly guiding multimode fiber （MMF） with a step-index profile when the surrounding refractive index （SKI） is lower than that of the coreless fiber. Thus, it becomes the conventional single-mode multimode single-mode （SMS） fiber structure but with a larger core size. The output spectra will shift along with the changes in the SKI owing to the direct exposure of the coreless fiber. The output spectra under different SKIs were numerically studied, as well as the sensitivities with different lengths and diameters of the coreless fiber. The predication and calculation showed the good agreement with the experimental results. The proposed RI sensor proved to be feasible by verification experiments, and the relative error was merely 0.1% which occupied preferable sensing performance and practicability.

Avian succession along ecological gradients： Insight from species-poor and species-rich communities of Sylvia warblers

The mechanisms responsible for species replacement during ecological successions is a long-standing and open debate. In this study, we examined the distribution of the Sardinian warbler Sylvia melanocephala along two grassland-to-forest gradients, one in a high-diversity area （Albera-Aspres chain in Catalonia： eight Sylvia warbler species） and one in a low-diversity area （Mount Hymittos in Greece： four species）. In Catalonia, distribution models suggested that the apparent exclusion of S. melanocephala from the open and forest ends of the gradient may be explained entirely by the preference of S. melanocephala for mid-successional shrublands. However, a joint analysis of both data sets revealed that： 1） S. melanocephala was more evenly dis- tributed along the vegetation gradient in Greece, suggesting ecological release in the low-diversity area; and 2） a distribution model assuming interspecific competition （based on the distribution of Sylvia species showing a negative co-occurrence pattern with S. melanocephala） had a significantly higher predictive ability than a distribution model based on habitat variables alone. Our study supports the view that species turnover along ecological gradients generally results from a combination of intrinsic preferences and interspecific competition [Current Zoology 57 （3）： 307-317, 2011].

Study on Distribution Pattern of Plant Diversity of Forest Vegetation in Luofu Mountain,Guangdong

Through sample plot survey and statistic analysis,this paper adopts ecological method to study the characteristics of plant diversity of forest vegetation in Luofu Mountain,Guangdong.The results show that there is a great plant diversity of forest vegetation in Luofu Mountain owing to the ascendancy of aqueous and thermal condition in subtropical zone.The total number of species in 4 500 m2 sample plot(s)are 170 with 3 870 individual plants in total;Dahl species richness index(D)is 44.932;Simpson diversity index(L,D)is 0.022,0.022;Simpson(1982)diversity index(D)is 3.806;Pielou evenness index(E)is 0.984 and Hulbert evenness index(E)is 0.815;Shannon-wiener diversity index(information index H')is 4.188;Asymmetry index(r)is 0.185.These indexes show that a better habitat will bring about plant diversity of forest vegetation,and the diversity of zonal vegetation shows that the higher latitude is,the less species of vegetation can be found.Besides,vertical change of plant diversity of forest vegetation in Luofu Mountain is obvious.Its species richness index and plant diversity index show that monsoon evergreen broad-leaved forest is the tallest,mountain evergreen broad-leaved forest follows as the second and conifer-broad-leaved mixed forest is the shortest.The Wilson β-diversity index,which is obtained by comparison between forest vegetation below 300 m and forest vegetation between 600-900 m,is 0.621.Calculated from comparison between forest vegetation in 600-1 100 m and forest vegetation in 900-1 100 m,the Wilson β-diversity index is 0.727;by comparing forest vegetation below 300 m with forest vegetation in 900-1 100 m,the Wilson β-diversity index is 1.877.This shows that the plant diversity of forest vegetation is affected by the change in gradient of elevation.

Modeling and Doppler measurement of X-ray pulsar

Generally,the Doppler caused by the velocity of the detector leads to distortion of the integrated profile of the X-ray pulsar,on the contrary,if the distortion can be used to measure the Doppler,then the velocity of the detector is easy to be solved.In view of this,the correlation of the periodic error arise from the Doppler and the integrated profile was analyzed,then,based on the Poisson distribution model of the X-ray Pulsar,a new signal model and the concept of the profile entropy was defined.Furthermore,the directly cumulated profile of the signal was modeled with the Doppler as a parameter,and then the Doppler was solved via optimal method.Simultaneously,the performance of phase measurement based on this method was studded.The analysis shows that this method can get rid of the periodic error due to the discrete sampling,and can obtain continuous phase estimation.The experiment verification shows the consistency of the theory and the experiment.

Computer Simulations and Measurements of RadialSolid Flow Distribution in a Riser

Comparisons between the numerical predictions from a two-phase model and the experimental hydrodynamic data have been performed in fully developed gas-solid flows for FCC catalysts. The resultssuggested the existence of self-similar solid flux profiles at low solid fluxes. Non-uniformity in theradial solids fluxes was found with a high solid flowing mainly downward near the wall. The modelpredictions were reasonably caught up the experimental trends.

Simulation of Velocity and Temperature Distributions of Displacement Ventilation System with Single or Double Heat Sources

In order to obtain a better understanding of flow characteristics of displacement ventilation, the three-dimensional numerical models are developed using the CFD technology. The numerical simulation results are verified by experiments, based on this, the velocity and temperature distribution of three-dimensional displacement ventilation system with single and double heat sources are studied. Velocity and temperature fields under two different cases of heat source are analyzed and compared. The numerical results show that there are three layers in vertical temperature fields of displacement ventilation system with single or double heat sources, and the vertical temperature distribution of single heat source is different from that of double heat sources. When indoor load is large, the comfort requirement of people indoor can＇t be satisfied with displacement ventilation system only, thus an additional refrigeration system is necessary. Furthermore, under the condition of two heat sources, the displacement ventilation parameters can＇t be computed simply according to single heat source inlet parameters, therefore the interaction between heat sources should be considered.