2016年夏季南海海盆水体颗粒物粒径分布特征

颗粒物粒径分布（Particle Size Distribution,PSD）代表了颗粒物浓度与颗粒物粒径之间的关系,影响着海洋生态环境和水体光学特性等。文章基于2016年夏季航次调查的生物光学剖面数据,研究了南海海盆海域PSD的分布特征。研究发现,幂律函数可以较好地拟合南海海盆区域的PSD,对数空间中的实测的PSD与模拟的PSD平均决定系数高达0.95。PSD斜率（ξ）的分布范围为[1.27,7.65],均值为3.93±0.56。南海海盆区域表层水体的ξ均值与全球大洋表层水体的ξ均值相近,但高于海湾等表层水体的ξ均值。ξ能较好地表征颗粒物平均粒径DA的大小,两者存在明显负相关关系,即ξ值越高,DA越小;反之,DA越大。通过分析T1断面的生物光学剖面数据及总体平均的PSD剖面数据,发现PSD剖面分布特征如下:1)表层水体的ξ值相对较高,且DA值相对较低,推测可能是由于微微型藻类为主导颗粒物所致;2)ξ值极小值层出现在次表层叶绿素浓度极大值层（Subsurface Chlorophyll Maximum Layer,SCML）中,并伴随DA极大值层的出现,其原因可能是SCML中的大粒径浮游植物占比显著增加;3)弱光层中的ξ值较SCML中的高,但略低于表层的ξ值,而DA则位于表层与SCML的DA之间,这可能与浮游植物及其碎屑的絮凝、分解、沉降等过程相关。PSD特征影响着海水的固有光学特性,分析发现:由于SCML中的叶绿素浓度增加,颗粒物散射系数（bp（532））和颗粒物后向散射系数(bbp（532）)也相应呈现显著增加的趋势。弱光层中的平均bp（532）与平均bbp（532）最小。ξ与颗粒物衰减光谱斜率之间呈高分散性,Boss等（2001b）的模型适合用于粗略估算区域性的ξ分布范围及均值。国家自然科学基金(41576030,41431176,4176045,4176044,41376042);;热带海洋环境国家重点实验室自主研究项目(LTOZZ1602);;广州市科技计划重点项目(201504010034,201707020023,201607020041);;广东省科技计划重点项目(2016A020222008);;中科院A类先导专项(XDA11040302)~

类泛素蛋白及其中文命名

泛素家族包括泛素及类泛素蛋白,约20种成员蛋白.近年来,泛素家族领域取得了迅猛发展,并已与生物学及医学研究的各个领域相互交叉.泛素家族介导的蛋白质降解和细胞自噬机制的发现分别于2004和2016年获得诺贝尔奖.但是,类泛素蛋白并没有统一规范的中文译名. 2018年4月9日在苏州召开的《泛素家族介导的蛋白质降解和细胞自噬》专著的编委会上,部分作者讨论了类泛素蛋白的中文命名问题,并在随后的\"泛素家族、自噬与疾病\"(Ubiquitinfamily,autophagy anddiseases)苏州会议上提出了类泛素蛋白中文翻译草案,此草案在参加该会议的国内学者及海外华人学者间取得了高度共识.冷泉港亚洲\"泛素家族、自噬与疾病\"苏州会议是由美国冷泉港实验室主办、两年一度、面向全球的英文会议.该会议在海内外华人学者中具有广泛影响,因此,参会华人学者的意见具有一定的代表性.本文介绍了10个类别的类泛素蛋白的中文命名,系统总结了它们的结构特点,并比较了参与各种类泛素化修饰的酶和它们的生物学功能.文章由45名从事该领域研究的专家合作撰写,其中包括中国工程院院士1名,相关学者4名,长江学者3名,国家杰出青年科学基金获得者18名和美国知名高校华人教授4名.他们绝大多数是参加编写即将由科学出版社出版的专著《泛素家族介导的蛋白质降解和细胞自噬》的专家

Efficient and Effective Solvers with Preconditions in the Parallel Software of Large-Scale Petroleum Reservoir Simulation

文章的主要工作围绕着如何精心构造一个面向大规模油藏数值模拟的并行模拟器来进行.为此,对线性问题的高效预处理求解方法进行了理论分析和技术研究.主要研究内容包括：求解非线性方程和线性方程的迭代方法,基于物理背景和代数背景的预处理技术,并行计算,非线性问题求解性能提高的途径等.文章的研究重点定位于如何提高油藏数值模拟非线性方程组的求解性能.围绕着研究对象,文章对极小剩余类和正交剩余类方法进行理论分析,提出并实现了针对油藏数值模拟求解器的“内迭代-外迭代”双重迭代模式.在预处理技术方面,文章将整体预条件子看作一个“系统”,提出并采用基于大规模分布式并行处理的、面向油藏数值模拟线性系统的、基于区域分解、粗网格、约束剩余、子空间投影校正技术和块不完全分解技术的整体预条件子构造模式.该论文的创造性内容主要包括：1）将油藏数值模拟中Watts校正进行广义化,形成代数粗网格校正预处理算法,并利用代数粗网格校正预处理代替Watts校正;2）提出并使用多角度子空间斜交投影方法来构造并行的线性方程求解方法的整体预条件子,利用两类预条件子形成两种最佳“预条件子+迭代算法”组合;3）非线性问题求解的Broyden快速算法在秩二校正的BFGS算法上推广,形成拟牛顿秩二BFGS校正快速算法;4）基于论文的工作,形成了油藏数值模拟的高效并行线性求解器、非线性求解器和油藏数值模拟并行软件.Petroleum reservoir simulation uses a numerical material balance approach to generate realistic development scenarios. Reservoir description data often comes in finely gridding geological models containing more grid cells than can be efficiently handled. Many large-scale simulations are still limited by the CPU frequency and memory requirements. The objective of our project that lead to the research motivation of this doctoral thesis is to develop a simulator that can be used for solving a variety of practical and challenging reservoir simulation problems. It is widely recognized that the most computationally expensive part is the solution of the sparse linear equations from finite-difference or finite-element discretization. In this dissertation, theoretical analysis and practical techniques of efficient and effective solvers with preconditions are elaborated for large-scale petroleum reservoir parallel simulators. Discussion details involved include methods of solving nonlinear and linear equations, preconditions rooted in both physical and algebraic backgrounds, parallelism, and performance improving approach.This dissertation discusses how to improve the performance of solving nonlinear equations originated from petroleum reservoir numerical simulations. Relating to this subject, minimal residual and orthogonal residual methods are theoretical analyzed and inner-outer iteration algorithms similar to FGMRES or GMRESR are introduced; two types of multipurpose oblique projection correction preconditions are used, one type being based on an incomplete LU decomposition to solve a small linear system of (P~TAP)z = r involved and the other being-based on iterative algorithms to solve that small system; two of best combinations of both Krylov subspace methods and preconditions are provided, numerical tests of petroleum reservoir data on parallel computers show that different Krylov subspace methods combinings with appropriate preconditions are able to achieve nearly optimal performance. In the end of the work, performance-improving approach is given which suggests to use quasi-newton efficient implementations combined with inexact newton methods, quasi-newton algorithm is used to associate linear system preconditions with nonlinear solvers in order to save the expense such as isolated construction of the ILU decomposition, inexact newton is used to associate linear solvers with nonlinear solvers in order to choose dynamic convergence tolerance and to avoid the phenomenon of over-solving. In order to analyze the manners and technical details of the used preconditions, characteristics of partial differential equations are introduced in the second chapter of the thesis. The originality work of the thesis includes : 1) as a generalization of Watts correction method, coarse grid correction preconditioning is considered instead of Watts correction; 2) multipurpose oblique projection correction preconditioning method is brought forward and implemented in the parallel solver,two types of the preconditioning are given in order to be combined with different Krylov subspace methods; 3) qnasi-newton Rank-2 BFGS correction efficient implementations are provided ; 4) parallel software , nonlinear and linear solvers are finished basing on the work of this thesis. Novel viewpoint in the thesis includes : 1) in the view of projection correction, we give out the general theory about Krylov subspace methods basing on minimal residual and orthogonal residual methods; 2) the analyse and efficiency display of decoupling operator; 3) the mathematical explanation of so-called combinative and CRP (constrained residual precondition) preconditions; 4) Numerical comparison and analyse of preconditioned Krylov subspace methods for a typical PDE problem and for petroleum reservoir simulation black oil model; 5) some analyse about nonlinear (damped) newton, quasi-newton algorithm and their interaction associating with linear solvers and preconditions. Other important works include: 1) characteristics of partial differential equations are introduced and analysed ; 2) introduction of iteration methods last century; 3) introduction of preconditions used in petroleum reservoir simulation; 4) introduction about nonlinear (damped) newton, quasi-newton methods; 5) a number of numerical experiments; 6) the work about parallel solvers and parallel simulators

從馬汀的社區教育模式論析台灣社區終生學習實務之實然與應然

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realization of gear method in index reduction

基于组件的建模有时会产生高指标的微分代数方程(DAE),不能直接求解,需要进行指标约简。Gear方法是一个经典的指标约简方法,对Gear方法从理论上进行了说明和分析。对于一类具有特殊结构的DAE,提出了Gear方法实现中的优化策略,以降低指标约简后得到的方程规模。把优化后的实现与未优化的实现进行了比对,实验结果表明,优化过的实现方法针对这类特殊的问题确实达到了更好的约简效果

multilevel hypergraph partitioning and multi-phase refinement

超图划分应用于大规模矩阵计算、大规模集成电路等领域.详细地阐述了超图多级划分的算法框架,并提出对划分结果进行优化的一种手段,通过进行多阶段的循环优化,在可以接受的运行时间内得到对超图的一个较优的划分

ILU preconditioner for NWP system：GRAPES

探讨了一种适用于我国自主研发的数值天气预报模式软件GRAPES的不完全LU(ILU)分解预条件子。针对GRAPES模式所特有的具有对角优势结构的赫姆霍兹方程系数矩阵,提出了一种有效的ILU分解方案,并将分解得到的预条件子应用到模式核心的动力积分计算迭代算法中,从而达到加速算法收敛,提高模式软件整体性能的目的

FRACTIONAL PARTIAL DIFFERENTIAL EQUATIONS AND NUMERICAL DISCRETIZATION;METHOD FOR PRICING AMERICAN OPTIONS

KOBOL、FMLS、CGMY等无限跳跃活动Levy模型下,期权定价可以表达为分数阶偏微分方程.欧式期权在部分情况下有解析表达式计算,而美式期权 定价属于线性互补问题,在这些无限跳跃活动模型下表达为包含分数阶偏微分方程的方程组,其同欧式期权定价相比更加复杂,只能采用数值方法. 在Cartea导出的欧式期权方程基础上,本文利用线性互补理论推导出针对美式期权的分数阶偏微分方程组,利用罚方法将分数阶偏微分方程组转化为单一方程 ,釆用Grunwald公式对分数阶偏微分方程设计出相应的数值离散格式,利用有限差分方法得到了每个时间步上的线性方程系统,采用迭代算法进行了线性方 程的求解,并进行了数值实验和结果分析,以此来证明分数阶偏微分方程组及其数值离散格式的有效性.基于分数阶偏微分方程对美式期权定价方程组的推导和相应 的数值离散格式,在当前的文献中未见报道.Under infinite jump activity models such as Kobol, FMLS and CGMY, the prices of financial derivatives, such as options, satisfy a fractional partial differential equation (FPDE). American options have an additional constraint for the value of the option, and due to this, they lead to linear complementarity problems (LCP). Thus, American options pricing are much more complicated than that of European Options. In this paper, based on the FPDE for pricing European options derived by Cartea, a method for pricing American options is proposed. In the frame of LCP, the FPDE is introduced to build a mathematical model for pricing American options. Then, the fractional parts are treated with Grunwald equation and a penalty method is employed to transform the LCP into linear equations at each time step in the scheme of finite difference. Finally,we present numerical tests which illustrate the effectiveness of the method

Modelica建模软件中拓扑排序相关算法研究

为了提高现有OpenModelica软件中对DAE系统的预处理模块中，求强连通分量与拓扑排序部分的性能，提出了基于Kosaraju算法实现的策略。首先阐述Modelica软件的实现原理，叙述拓扑排序相关算法在其中的重要性，再分析现有Modelica软件中使用的求强连通分量与拓扑排序部分的算法，然后比较Tarjan算法的实现方案与Kosaraju算法实现方案。通过实现两种方案，并对实验结果进行比较和分析，验证了Kosaraju算法方案的可行性和有效性