随机数在随机事件与概率教学中的应用探索

本文对在随机事件与概率中的常见问题提出了一种新的借助于计算机实现的解决思路,即通过机器自动产生随机数后构建相应的数学模型,再通过编程计算得到最后结果。该方法既为概率论的教学带来了创新性思维,也为当前的教师提出了新的挑战。     

Neoliberalization,Housing Institutions and Variegated Gentrification: How the ‘Third Wave’ Broke in Amsterdam

Neil Smith argues that in the last two decades gentrification has become a generalized global urban phenomenon. His theory is at a high level of abstraction, as it links urban gentrification to globalization, financial capitalism and neoliberalization. With these global processes, all cities have experienced ‘third wave’ gentrification. The theory, however, leaves little room for variegations of gentrification, apart from characterizing geographical differences as idiosyncrasies or as minor variations. This downplays the role of intervening mechanisms that impinge upon the pursuit and social outcomes of gentrification. This article aims to amend abstract theory by looking at Amsterdam from a historical institutional perspective. In Amsterdam, gentrification was particularly made possible by a process of neoliberalization within the housing system. However, as institutional change is incremental and based on layering and conversion, many older institutional arrangements remain in place. These arrangements tend to slow gentrification and assuage social consequences. Nevertheless, neoliberal modifications to the housing system have been accelerating the pursuit of gentrification. Current policies will very likely lead to exclusionary displacement.     

Simulating Price-Taking

In this article, the author presents a price-takers’ market simulation geared toward principles-level students. This simulation demonstrates that price-taking behavior is a natural result of the conditions that create perfect competition. In trials, there is a significant degree of price convergence in just three or four rounds. Students find this simulation to be a fun, educational experience that adds value to their understanding of competitive markets.     

Selecting make-to-stock and postponement policies for different products in a chemical plant: A case study using discrete event simulation

We present a guideline for selecting the inventory management policy for a specialty chemical plant that produces products with limited shelf life, by producing multiple grades of bulk chemical and packaging them into a large variety of bottles. The policy for each product was selected based on a cost-benefit analysis, using the multiple objectives of maximizing the on time order fulfillment, minimizing the production (cleaning and shelf life expiration) and inventory costs. To generate realistic cost estimates, we developed a discrete event simulation model that included demand variability, planning and scheduling policies, and operational details. We evaluated three different policies: make-to-stock (MTS), postponement, and combined MTS/postponement. We also evaluated different storage media and optimized the number of storage units for products selected for postponement. A combined MTS/postponement policy, in which postponement is applied to products with low to medium demand and high expiration provided lowest costs without significantly impacting the customer on time order fulfillment. For all other products, a MTS policy is applied to maximize order fulfillment on time, reduce cleaning costs and to reduce number of storage units.     

马克思主义文艺思想的现实指引——六中全会决定和胡锦涛讲话理论溯源

党的十七届六中全会关于深化文化体制改革推动社会主义文化大发展大繁荣若干重大问题的决定，和胡锦涛总书记在中国文联第九次和中国作协第八次代表大会上的讲话，都从马克思主义文艺思想出发，在艺术实践规律的基础上提出并阐发了许多文艺理论的重大问题。而关于文艺家要承担历史责任、提倡文以载道、鼓励文艺原创、自觉抵制低俗之风等，都是当前深具实践意义与艺术学理意义的重大问题。如从理论与实际相结合的意义上加以深入领会，必然会有力推动社会主义文艺的大发展大繁荣的伟大战略目标的早日实现。     

急诊实践教学方法探讨:PBL联合模拟教学法

急诊医学作为一门临床综合学科,其医学的范畴涉及多个专科,具有急迫性、综合性、实践性、复杂性等特点,实践教学难度较大。我院在急诊医学实践教学中,采用以问题为基础的教学法(PBL)联合模拟教学法,显著提高学生的学习主动性,有效地建立急诊临床思维,培养学生实践能力及知识运用能力,促进急诊医学理论知识的深入掌握,提高教学效果。     

上部覆盖层下伏页岩一类潜在滑坡演化变形机制分析

为研究上部覆盖层下伏页岩这一类型的滑坡失稳变形,需要确定其变形的潜在影响因素,从定量角度上分析这一类型滑坡灾害的变形演化问题。以容县六王镇西流河潜在滑坡为研究对象,借助钻孔勘探、室内试验和地质调绘,详细分析了西流河滑坡的工程地质概况,并推测其可能的变形演化机制,然后利用Geostudio数值软件建立西流河滑坡的渗流模型,模拟其在不同降雨工况下的渗流规律。研究发现:西流河滑坡在持续降雨过程中稳定性系数从1.224逐步降低至1.09,稳定性系数不断下降,滑坡体内由垂直入渗逐步转化沿滑动带稳定渗流;当遭遇极端暴雨情况(50年重现期)时,滑坡体内稳定渗流场显著增厚,饱和滑带土增多,滑坡安全储备达到极限。由此可以得出:上部覆盖层下伏页岩一类滑坡变形演化过程主要分滑坡体上部覆盖层堆积阶段,垂直入渗至页岩富水软化阶段和稳定渗流至潜在滑动带软化蠕变这3个阶段;其中上部覆盖层的高渗透性和下伏页岩的隔水特征是导致页岩风化带软化蠕变和稳定渗流场形成的关键因素。研究结果为上部覆盖层下伏页岩这一类滑坡影响因素的研究提供了一些证据,对研究滑坡演化变形机制具有借鉴意义。     

A robust VaR model under different time periods and weighting schemes

This paper analyses several volatility models by examining their ability to forecast Value-at-Risk (VaR) for two different time periods and two capitalization weighting schemes. Specifically, VaR is calculated for large and small capitalization stocks, based on Dow Jones (DJ) Euro Stoxx indices and is modeled for long and short trading positions by using non parametric, semi parametric and parametric methods. In order to choose one model among the various forecasting methods, a two-stage backtesting procedure is implemented. In the first stage the unconditional coverage test is used to examine the statistical accuracy of the models. In the second stage a loss function is applied to investigate whether the differences between the models, that calculated accurately the VaR, are statistically significant. Under this framework, the combination of a parametric model with the historical simulation produced robust results across the sample periods, market capitalization schemes, trading positions and confidence levels and therefore there is a risk measure that is reliable.

Property rights and information flows: a simulation approach

With the growth of the information economy, the proportion of knowledge-intensive goods to total goods is constantly increasing. Lessig (The future of ideas: the fate of the commons in a connected world. Vintage, New York 2001) has argued that IPRs have now become too favourable to existing producers and that their ‘winner-take-all’ characteristics are constraining the creators of tomorrow. In this paper we look at how variations in IPRs regimes might affect the creation and social cost of new knowledge in economic systems. Drawing on a conceptual framework, the Information Space or I-Space to explore how the uncontrollable diffusibility of knowledge relates to its degree of structure, we deploy an agent-based modelling approach to explore the issue of IPRs. We take the ability to control the diffusibility of knowledge as a proxy measure for an ability to establish property rights in such knowledge. Second, we take the rate of obsolescence of knowledge as a proxy measure for the degree of turbulence induced by different regimes of technical change. Then we simulate the quantity and cost to society of new knowledge under different property right regimes.