碳纳米管增强水泥基复合材料的 二维代表单元研究

为了从细微观尺度上研究碳纳米管-水泥基复合材料的损伤破坏过程和破坏机理,从碳纳米管-水泥基复合材料中选取尺寸为100μm×100μm的代表单元,建立二维代表单元的细微观层次的数值模型。以势能原理的基面力元法为理论基础,对代表单元进行数值模拟,探究在单轴受压状态下碳纳米管-水泥基复合材料的力学性能变化,并绘制破坏裂纹的发展过程图和最大主应力分布变化过程图。结果表明,该代表单元模型能够较真实地模拟复合材料在单轴压缩状态下的损伤破坏过程,通过数值模拟不同含量的复合材料代表单元模型,发现增强体的含量影响着复合材料的强度及韧性,选择合适的含量范围有利于提升材料的力学性能。通过数值模拟的方法分析碳纳米管增强水泥基复合材料的作用机理,拓展了基面力元法的应用范围,节约了计算资源,其结果丰富了碳纳米管-水泥基复合材料力学性能的研究,可为相关工程应用及基础研究提供参考。     

基于文化旅游视角的历史文化资源产业开发——以福建省泉州市为例

历史文化资源是人类文化创造的历史积累和结晶,为人们提供极其丰富的精神财富,是当前学术界和实业界普遍关注的一个重大课题。回顾了历史文化资源开发的理论脉络,探讨泉州市加强历史文化资源开发的客观必然性,从文化旅游视角分析了当前泉州市历史文化资源开发的现状和存在的问题,并在此基础上从文化旅游视角提出了一些促进泉州市历史文化资源开发的建议和对策。     

呼伦贝尔非公有制经济的历史变迁

建国前,呼伦贝尔牧区的私营经济主要是指旅蒙商人进行的商业活动。建国后,呼伦贝尔个体经济、私营经济等非公有制经济经过长期曲折的发展,现阶段已是呼伦贝尔市经济的重要组成部分。建国后呼伦贝尔非公有制经济的发展历程可以分为社会主义改造时期、恢复时期、稳定时期以及发展和壮大五个时期。     

新型钢板螺栓连接装配式混凝土剪力墙抗震性能研究

为解决目前装配式剪力墙水平缝常用的套筒灌浆连接存在注浆不易、钢筋不易对齐等问题,提出了一种新型钢板螺栓连接装配式混凝土剪力墙结构,并采用有限元软件分析其抗震性能。依据试验工况建立了螺栓连接装配式剪力墙（PSW-1）、新型钢板螺栓连接装配式剪力墙（PSW-2）、普通现浇墙（SW-1）3个有限元模型,并分析了不同轴压比及剪跨比对试件PSW-2抗震性能的影响。结果表明：试件PSW-2承载力随轴压比增大而提高,随剪跨比增大而降低;试件PSW-2的耗能能力相比试件PSW-1,SW-1分别提高了31%,16%,延性分别提高了8%,14%,因此,在混凝土剪力墙中预埋钢板,可有效提高混凝土剪力墙的耗能能力和延性。研究结果得到了新型装配式混凝土剪力墙的部分抗震性能指标,可为其在实际工程中的应用提供一定的参考。     

边测边调井下流量计校准装置模拟井筒标准化的探讨

通过调研、理论分析、试验、实验等方法主要对边测边调井下流量计校准装置模拟井筒的井身结构进行分析和探讨:目前的井身结构不能同时进行吊测和坐测校准,如同时进行吊测和坐测校准,则以30倍管道直径计算(不考虑层流)模拟井筒深度至少为7.7m;在坐测位置上提0.3m进行吊测校准,结论是否定的,所以目前所见模拟井筒不能同时进行吊测和坐测校准;在存储流量计模拟井筒(光油杆)中进行吊测校准,在边测边调模拟井筒中进行坐测、坐测支路和水嘴功能测试。     

A model study about the applicability of the Chain Ladder method

Loss Reserving is a major topic of actuarial sciences with a long tradition and well-established methods – both in science and in practice. With the implementation of Solvency II, stochastic methods and modelling the stochastic behaviour of individual claim portfolios will receive additional attention. The author has recently proposed a three-dimensional (3D) stochastic model of claim development. It models a reasonable claim process from first principle by integrating realistic processes of claim occurrence, claim reporting and claim settlement. This paper investigates the ability of the Chain Ladder (CL) method to adequately forecast outstanding claims within the framework of the 3D model. This allows one to find conditions under which the CL method is adequate for outstanding claim prediction, and others in which it fails. Monte Carlo (MC) simulations are performed, lending support to the theoretic results. The analysis leads to additional suggestions concerning the use of the CL method.     

Towards Post-neoliberal Resource Politics? The International Political Economy (IPE) of Oil and Copper in Brazil and Chile

The contemporary commodity boom is unprecedented in two ways. On the one hand, it takes place against the backdrop of the failure of neoliberal policies to achieve stable economic growth in Latin America. On the other hand, Left-of-centre governments, which have now been in power for over a decade, are designing new strategies to manage the increase in export earnings accrued from sustained international demand for commodities. In particular, Brazil and Chile have undergone significant market opening reforms in their resource sectors, yet persistent state ownership and the dominant role of state enterprises in key extractive industries continue to characterise their growth models. This article explains this puzzle through the application of Mahoney and Thelen's (2010) historical institutionalist framework on incremental change. In so doing, it offers a process-oriented approach in exploring how resource wealth under certain economic and political conditions provides leverage for states to promote economic development. In sum, the article hopes to contribute to the literature on neoliberal and post-neoliberal political economies in Latin America.     

国产车规级芯片合作研发演化博弈分析

为解决国产车规级芯片合作研发的问题,建立新能源汽车生产企业、芯片研发企业和地方政府为博弈参与主体的演化博弈模型,根据收益矩阵得到各参与主体稳定策略的约束条件,并仿真模拟各主体在不同参数下的动态演化过程。研究发现,各主体行为相互影响且在一定条件下可收敛到理想的稳定策略,主体的初始参与意愿、合作的利益分配以及政府对企业的合作激励等均是影响车规级芯片合作研发的重要因素。     

社会经济因素对农户种植决策行为的影响——基于主体模型的像元尺度模拟

[目的]保证粮食安全关乎国计民生和社会稳定。合理调控种植结构,优化粮食配比和产量,对于稳定粮食安全有着举足轻重的作用。目前,以大豆为主的油料作物多依赖进口,严重威胁我国的粮食安全,为了优化种植结构,提升油料作物自给率,对农户种植决策行为的研究十分必要,具有科学价值和政策意义。[方法]文章选取黑龙江省松嫩平原粮食主产区的主粮种植结构为研究对象,通过农户问卷调查并结合社会经济统计数据以及作物空间分布数据,采用基于主体模型（Agent-based Model,简称ABM模型）模拟了2016—2020年农户作物种植（大豆、水稻、玉米）的决策行为以及作物空间分布格局。[结果]ABM模型模拟的平均总体精度为63%,结果显示种植决策行为与社会规范因素较为相关,例如：农户所处周边社会环境中大多数人种植水稻,该农户有较高的概率选择种植水稻;经济因素也是重要的影响因素,例如：水稻种植收益高则更多人种水稻。根据ABM模型的情景分析结果显示,农户受周围农户种植决策影响程度越高,越倾向于选择周围农户的种植结构;而当大豆补贴金额变化时,农户更倾向于选择种植收入较高的种植结构。[结论]该研究构建的基于农户决策行为的...     

Option pricing with the control variate technique beyond Monte Carlo simulation

Although mostly used alongside Monte Carlo simulation, the control-variate (CV) technique can be applied to other numerical algorithms in option pricing. This paper studies the conditions under which a numerical method (simulation-based or not) can benefit from the CV technique and what approximators can serve as CVs. We demonstrate the ideas with Carr and Madan’s Fourier transform-based algorithm, convolution-based pricing algorithms, and classic binomial trees. Numerical results are provided to show that the CV-enhanced versions are more efficient than the original algorithms.