基于多层面改进多域法的航行船舶时域水动力分析

针对航行船舶三维时域水动力分析问题,本文采用多域高阶边界元法(MDHOBEM, Multi-Domain Higher Order Boundary Element Method)开展研究,通过假设控制面,将计算域分为内域和外域两部分,内域采用Rankine面元法,外域使用自由面格林函数法,内外域联立求解。从内域、外域、波浪激励三个层面改进多域法的精度、计算效率,以适应不同工况需求。内域重新推导非线性边界条件,考虑入射波对绕辐射问题计算的影响,提高大幅波浪中运动计算精度;外域采用垂向积分形式自由面格林函数,提高格林函数积分计算的收敛性、稳定性及计算效率;波浪激励采用高阶谱(HOS, High Order Spectral)方法生成演化的波场,考虑波浪自身的非线性,提高对非线性现象的捕捉和模拟能力。以C11船为对象,研究内域非线性改进对船舶大幅运动计算精度的提高;以S175集装箱船为对象,验证外域垂向积分对运动及波阻增加计算效率和稳定性的提高;对比S175在线性波场和非线性波场中的运动,论证考虑非线性波场对运动计算的影响;以某内倾船为对象,研究不同层次改进对参数横摇现象捕捉的影响,验证非线性波浪激励对多域法非线性现象捕捉能力的提升;整体上形成不同层面改进多域法,为不同工况下时域水动力分析提供理论和程序支撑。

多域Rankine-Kelvin源法计算浮体水动力方法研究

文章采用无限长无网格圆柱面作为控制面将流体域分为内域与外域,内域使用简单Green函数(Rankine源),外域使用满足自由表面Green函数(Kelvin源),圆柱控制面上的速度势与速度势法向导数采用Laguerre-Fourier级数进行展开。将两种水动力方法的结合既可以保持两种方法的优点又可以减少自由面上网格划分面积且内域只需要计算一次。无限长圆柱绕射势存在解析解,利用该解析解对Laguerre-Fourier级数展开速度势的精度进行验证。采用半球作为浮体,将附加质量与阻尼系数的数值解和解析值进行对比,验证该算法的精度。

三维边界元多域缩聚法分析

采用超参非连续边界元离散边界积分方程及三角极坐标变换方法处理奇异积分。将超参非连续元应用于多城边界元法分析，解决了自由度约束问题，提出了二次缩聚的概念．提高了多域缩聚边界元法的求解效率。

多域自然应力边界积分方程

文章通过对常规应力边界积分方程反复的分部积分,将应力表示成位移ui、面力ti及自然变量wi的积分形式,并推广到多域系统,建立了多域自然应力边界积分方程;该积分方程仅含几乎强奇异积分,同常规应力边界积分方程所含的几乎超奇异积分相比,奇异性降低了一阶;再利用正则化技术解析处理多域自然应力边界积分方程中的几乎强奇异积分,从而可以准确计算多域系统近边界内点的应力。

MARS:A General Multilayer Area Router

Based on a ripped-up and rerouted methodology,a multilayer area detailed router is presented by using simulated evolution technique.A modified maze algorithm is also performed for the single net.

Multi-scale seismic full waveform inversion in the frequency-domain with a multi-grid method

Although full waveform inversion in the frequency domain can overcome the local minima problem in the time direction, such problem still exists in the space direction because of the media subsurface complexity. Based on the optimal steep descent methods, we present an algorithm which combines the preconditioned bi-conjugated gradient stable method and the multi-grid method to compute the wave propagation and the gradient space. The multiple scale prosperity of the waveform inversion and the multi-grid method can overcome the inverse problems local minima defect and accelerate convergence. The local inhomogeneous three-hole model simulated results and the Marmousi model certify the algorithm effectiveness.

On Univalent Functions in Multiply Connected Domains

The present article is an account of results on univalent functions in multiply connected domains obtained by the author. It contains two rery simple proofs of Villat's formula; Schwarz's formula, Poisson's formula and Poisson-Jensen formula in multiply connected domains; the differentiability theorem with respect to the parameter of analytic function family containing one parametric variable on multiply connected domains; variation theorem and parametric representation theorem of univalent functions in multiply connected domains; the solution of an extremal problem of differentiable functionals.

Parallel programming characteristics of a DSP-based parallel system

This paper firstly introduces the structure and working principle of DSP-based parallel system, parallel accelerating board and SHARC DSP chip. Then it pays attention to investigating the system’s programming characteristics, especially the mode of communication, discussing how to design parallel algorithms and presenting a domain-decomposition-based complete multi-grid parallel algorithm with virtual boundary forecast (VBF) to solve a lot of large-scale and complicated heat problems. In the end, Mandelbrot Set and a non-linear heat transfer equation of ceramic/metal composite material are taken as examples to illustrate the implementation of the proposed algorithm. The results showed that the solutions are highly efficient and have linear speedup.

An Explicit-Implicit Predictor-Corrector Domain Decomposition Method for Time Dependent Multi-Dimensional Convection Diffusion Equations

The numerical solution of large scale multi-dimensional convection diffusion equations often requires efficient parallel algorithms.In this work,we consider the extension of a recently proposed non-overlapping domain decomposition method for two dimensional time dependent convection diffusion equations with variable coefficients. By combining predictor-corrector technique,modified upwind differences with explicitimplicit coupling,the method under consideration provides intrinsic parallelism while maintaining good stability and accuracy.Moreover,for multi-dimensional problems, the method can be readily implemented on a multi-processor system and does not have the limitation on the choice of subdomains required by some other similar predictor-corrector or stabilized schemes.These properties of the method are demonstrated in this work through both rigorous mathematical analysis and numerical experiments.

Multi-path routing algorithm in WSN using an improvedparticle swarm optimization

To slove the problems of constrained energy and unbalanced load of wireless sensor network(WSN)nodes,a multipath load balancing routing algorithm based on neighborhood subspace cooperation is proposed.The algorithm adopts the improved particle swarm optimization(PSO)algorithm,takes the shortest distance and minimum energy consumption as optimization target and divides the nodes in one-hop neighborhood near the base station area into different regions.Furthermore,the algorithm designs a fitness function to find the best node in each region as a relay node and forward the data in parallel through the different paths of the relay nodes.The simulation results show that the proposed algorithm can reduce energy consumption and average end-to-end delay,balance network load and prolong network lifetime effectively.

Using Path Analysis to Identify the Influence of Climatic Factors on Spring Peak Flow Dominated by Snowmelt in an Alpine Watershed

Spring snowmelt peak flow （SSPF） can cause serious damage. Precipitation as rainfall directly contributes to the SSPF and influences the characteristics of the SSPF, while temperature indirectly impacts the SSPF by shaping snowmelt rate and determining the soil frozen state which partitions snowmelt water into surface runoff and soil infiltration water in spring. It is necessary to identify the important and significant paths of climatic factors influencing the SSPF and provide estimates of the magnitude and significance of hypothesized causal connections between climatic factors and the SSPF. This study used path analysis with a selection of five factors - the antecedent precipitation index （API）, spring precipitation （SP）, winter precipitation as snowfall （WS）, 〈0℃ temperature accumulation in winter （[ATNI）, and average 〉0℃temperature accumulation in spring （AT） - to analyze their influences on the SSPF in the Kaidu River in Xinjiang, China. The results show that {ATN}, AT and WS have a significant correlation with the SSPF, while API and SP do not show a significant correlation. AT and WS directly influence the SSPF, while as the influence of[ATN] on SSPF is indirect through WS and AT. The indirect influence of [ATN[ on SSPF through WS accounts for 69% of the total influence of [ATN] on SSPF. Compared to the multiple linear regression method, path analysis provides additional valuable information, including influencing paths from independent variables to the dependent variable as well as direct and indirect impacts of external variables on the internal variable. This information can help improve the description of snow melt and spring runoff in hydrologic models as well as the planning and management of water resources.

Model predictive control synthesis algorithm based on polytopic terminal region for Hammerstein-Wiener nonlinear systems

An improved model predictive control algorithm is proposed for Hammerstein-Wiener nonlinear systems.The proposed synthesis algorithm contains two parts:offline design the polytopic invariant sets,and online solve the min-max optimization problem.The polytopic invariant set is adopted to replace the traditional ellipsoid invariant set.And the parameter-correlation nonlinear control law is designed to replace the traditional linear control law.Consequently,the terminal region is enlarged and the control effect is improved.Simulation and experiment are used to verify the validity of the wind tunnel flow field control algorithm.

IMPROVED DELAUNAY TRIANGULATION FOR TRIMMED NURBS SURFACE

An improved algorithm of Delaunay triangulation is proposed by expanding the scope from a convex polygon to an arbitrary polygon area in which holes can be contained in the subdivision procedure. The data structure of generated triangles and the exuviationslike method play a key role, and a single connectivity domain (SCD) without holes is constructed as the initial part of the algorithm. Meanwhile, some examples show that the method can be applied to the triangulation of the trimmed NURBS surface. The result of surface tessellation can be used in many applications such as NC machining, finite element analysis, rendering and mechanism interference detection.

Guest Review:Potential theory method for 3D crack and contact problems of multi-field coupled media: A survey

This paper presents an overview of the recent progress of potential theory method in the analysis of mixed boundary value problems mainly stemming from three-dimensional crack or contact problems of multi-field coupled media. This method was used to derive a series of exact three dimensional solutions which should be of great theoretical significance because most of them usually cannot be derived by other methods such as the transform method and the trial-and-error method. Further, many solutions are obtained in terms of elementary functions that enable us to treat more complicated problems easily. It is pointed out here that the method is usually only applicable to media characterizing transverse isotropy, from which, however, the results for the isotropic case can be readily obtained.

Responses of River Runoff to Climate Change Based on Nonlinear Mixed Regression Model in Chaohe River Basin of Hebei Province, China

Taking the nonlinear nature of runoff system into account,and combining auto-regression method and multi-regression method,a Nonlinear Mixed Regression Model (NMR) was established to analyze the impact of temperature and precipitation changes on annual river runoff process. The model was calibrated and verified by using BP neural network with observed meteorological and runoff data from Daiying Hydrological Station in the Chaohe River of Hebei Province in 1956–2000. Compared with auto-regression model,linear multi-regression model and linear mixed regression model,NMR can improve forecasting precision remarkably. Therefore,the simulation of climate change scenarios was carried out by NMR. The results show that the nonlinear mixed regression model can simulate annual river runoff well.

The Common Principal Component Analyses of Multi-RCMs

Based on a 10-year simulation of six Regional Climate Models(RCMs) in phase II of the Regional Climate Model Inter-Comparison Project(RMIP) for Asia,the multivariate statistical method of common principal components(CPCs) is used to analyze and compare the spatiotemporal characteristics of temperature and precipitation simulated by multi-RCMs over China,including the mean climate states and their seasonal transition,the spatial distribution of interannual variability,and the interannual variation.CPC is an effective statistical tool for analyzing the results of different models.Compared with traditional statistical methods,CPC analyses provide a more complete statistical picture for observation and simulation results.The results of CPC analyses show that the climatological means and the characteristics of seasonal transition over China can be accurately simulated by RCMs.However,large biases exist in the interannual variation in certain years or for individual models.

Evaluation of Gold Geochemical Anomalies in the Liaodong Paleorift

89 Au geochemical anomalies are delineated by using 1/200000 regional geochemical exploration data. By researching regional geochemical characteristics and the relationship with the geological background, the author points out that： the main factors causing high background of Au geochemical anomalies are Gaixian and Dashiqiao formation of Liaohe group, intrusions of Mesozoic intermediate-acid intrusive rocks. The elements combination types of typical anomalies are determined by using factorial analysis,cluster analysis and other mathematical methods with the combination of elements association in typical anomalies：the composite anomaly of Baiyun gold deposits is Au-As-Sb, Maoling gold deposit is Au-As- Bi-Mo, Wulong gold deposits is Au-As-Bi-W, Xiaotongjiapuzi gold deposit is Au-As-Bi-Mo-Sb. By using multivariate statistical analysis method,62 ore-caused anomaly are preferred in 89 Au geochemical anomalies delineated. On this basis, the 62 anomalies are divided into 4 kinds of anomaly types reference to elements combination types of typical anomalies,the classification results of ore-caused anomalies are： 4 geochemical anomalies of Baiyun type,36 geochemical anomalies of Maoling type,11 geochemical anomalies of Wulong type, 11 geochemical anomalies of Xiaotongjapuzi type. According to the results, the prospecting direction is provided for the futme of gold exploration.

The Contemporary Construction of Chinese International Law Discourse

The contemporary construction of Chinese international law discourse, on the one hand, ought to precisely, systematically and completely express and communicate fundamental principles, main regimes and substantial features of international law as well as core values, basic conceptions, key terms, mainstream theories or doctrines and representative views gradually established and developed in the study of international law; on the other hand, it should fully and in a timely way manifest China＇s creative contributions to international law and its discipline and discourse. The framework of contemporary Chinese international law discourse should take ＂building a harmonious world＂ as the guiding rationale; thoroughly cover the four basic dimensions of the international rule of law and Chinese foreign policy and its practice, namely domestic, multilateral, regional and bilateral; coincide with, follow and respect those rules, natural laws and tendencies such as fundamental rules governing international relations, globalization, multilateralism, regional integration and regionalism, the international community＇s obligations （or rights） and China＇s needs for peaceful development. It should orient its basic functions toward promoting the continuous development and wide application of contemporary international law as well as its teaching, study and dissemination, stimulating the progress of the rule of law in China, protecting Chinese interests, especially those core national interests, and strengthening China＇s international image and status as a responsible big country.

Two-Level Additive Schwarz Methods Using Rough Polyharmonic Splines-Based Coarse Spaces

This paper introduces a domain decomposition preconditioner for elliptic equations with rough coefficients. The coarse space of the domain decomposition method is constructed via the so-called rough polyharmonic splines （RPS for short）. As an approximation space of the eUiptic problem, RPS is known to recover the quasi-optimal convergence rate and attain the quasi-optimal localization property. The authors lay out the formulation of the RPS based domain decomposition preconditioner, and numerically verify the performance boost of this method through several examples.

GVW ALGORITHM OVER PRINCIPAL IDEAL DOMAINS

GVW algorithm was given by Gao, Wang, and Volny in computing a Grobuer bases for ideal in a polynomial ring, which is much faster and more simple than F5. In this paper, the authors generalize GVW algorithm and present an algorithm to compute a Grobner bases for ideal when the coefficient ring is a principal ideal domain. K