Estimating the tensile strength of super hard brittle materials using truncated spheroidal specimens

New approaches need to be introduced to measure the tensile capacity of super hard materials since the standard methods are not effective. To pursue this objective, a series of laboratory tests were constructed to replicate the fracture mechanism of diamond-based materials. Experiments indicate that under a certain compressive test condition, stresses normal to the axisymmetric line in truncated spheroidal specimens (bullet-shaped specimens) are in tension contributing to the tensile fracture of the material. From experimental and numerical studies, it is concluded that semi-prolate spheroidal specimens can be used to determine precisely the tensile strength of brittle stiff diamond-like composites.     

6国高中化学教材中“化学平衡”内容比较

对6国高中化学教材“化学平衡”内容进行了研究,从内容选择、组织编排和呈现3个方面进行比较,分析了各国高中化学教材的特点与优势,重点得出中国高中化学教材在“化学平衡”内容编排、呈现方面的不足及参考性建议。     

结构性油价波动对中国股市的非对称性影响分析

本文分别检验了不同驱动因素所致的油价波动(结构性油价波动)对我国股市收益波动的非对称性影响,并探寻了油价波动对我国股市产生非对称性影响的来源。首先利用SVAR模型将油价波动分解为供给、需求和预防性购买三种驱动因素所致的油价波动,发现三种驱动因素所致的油价波动对我国股市收益的影响存在显著差异;GARCH非对称模型检验及其信息影响曲线结果显示供给和预防性购买因素所致的油价波动是对我国股市的产生非对称性影响的主要原因。在应对油价波动策略时,区分油价波动背后的驱动因素有助于政府机构采取行之有效的宏观调控。     

Chemical safety in a vulnerable world

The title of this article is the motto of the fourth meeting of the Intergovernmental Forum on Chemical Safety (Forum IV), which is to be held in Bangkok in November 2003. The IFCS has been in existence for 10 years. During this period politicians, scientists, and the general public have become increasingly aware of the risks associated with chemicals. International conventions providing for prohibitions and restrictions of dangerous chemicals, and for better control of trade have been set up. These conventions will soon be binding under international law. In developing countries many people who handle or use hazardous chemicals are illiterate or poorly educated; they may not fully understand what they are handling. The industrialized countries therefore have a special duty to incorporate chemical safety in development cooperation measures. Through their presence at this year's forum, prominent chemists such as Carl Djerassi will seek to underline the fact that a long term preventive approach to healthcare and the environment is only possible through international cooperation. This overview describes current developments in the field of chemical safety policy and presents a selection of the legislation currently in force for chemicals in the European Union. It also provides an insight into the interwoven structure of international cooperation that takes place at both the political and the technical level.     

International financial networks with intermediation: modeling,analysis, and computations

In this paper, we develop a framework for the modeling, analysis, and computation of solutions to international financial networks with intermediation. We consider three tiers of decision-makers consisting of: source agents in different countries, financial intermediaries, and consumers associated with the demand markets for different products in distinct currencies and countries. We model the behavior of the decision-makers, derive the equilibrium conditions, and establish the variational inequality formulation. We then utilize the variational inequality formulation to obtain qualitative properties of the equilibrium financial flow and price pattern as well as to propose an algorithm along with convergence results. Numerical examples are presented to illustrate both the model and the computational procedure. This research extends the recent results surrounding the modeling of financial networks with intermediation to the international dimension.Revised: January 2003, AMS Classification: 90, 91     

国际贸易中汇率调整的影响分析

本文用对策论主要分析行业内国际贸易中，汇率调整对贸易国净社会福利的影响．证明存在值e，汇率e＞e和e＜e，提高汇率对该国净社会福利的影响结果是不同的．并给出了e具有经济意义的上下界及计算途径．     

The Application of Kernel Smoothing to Time Series Data

There are already a lot of models to fit a set of stationary time series, such as AR, MA, and ARMA models. For the non-stationary data, an ARIMA or seasonal ARIMA models can be used to fit the given data. Moreover, there are also many statistical softwares that can be used to build a stationary or non-stationary time series model for a given set of time series data, such as SAS, SPLUS, etc. However, some statistical softwares wouldn＇t work well for small samples with or without missing data, especially for small time series data with seasonal trend. A nonparametric smoothing technique to build a forecasting model for a given small seasonal time series data is carried out in this paper. And then, both the method provided in this paper and that in SAS package are applied to the modeling of international airline passengers data respectively, the comparisons between the two methods are done afterwards. The results of the comparison show us the method provided in this paper has superiority over SAS＇s method.     

Competitive Advertising Under Uncertainty: A Stochastic Differential Game Approach

We analyze optimal advertising spending in a duopolistic market where each firm's market share depends on its own and its competitor's advertising decisions, and is also subject to stochastic disturbances. We develop a differential game model of advertising in which the dynamic behavior is based on the Sethi stochastic advertising model and the Lanchester model of combat. Particularly important to note is the morphing of the sales decay term in the Sethi model into decay caused by competitive advertising and noncompetitive churn that acts to equalize market shares in the absence of advertising. We derive closed-loop Nash equilibria for symmetric as well as asymmetric competitors. For all cases, explicit solutions and comparative statics are presented.     

Standardization of methods for the determination of traces of mercury: Part 5. Determination of Total Mercury in Water

For the determination of total mercury in water, two procedures based on cold-vapour atomic absorption spectrometry are given, each with and without a concentration step. These procedures have been accepted as reference methods by the member companies of the Bureau International Technique du Chlore. The methods give reliable results down to a concentration of 0.2 μg of mercury per litre of water. Results of an interlaboratory test involving 22 laboratories are reported. At the 0.75 μg Hg l^-1 level the results did not differ significantly; the coefficient of variation for repeatability was 3.8–10.9% and the coefficient of variation for reproducibility 7.2–29.4% for the different methods.     

New developments of the R&;D silicon tracking for linear collider on silicon trackers

The status of the R&D activity achieved so far within the SiLC (silicon tracking for the linear collider) collaboration is reported here. It includes the following items: present status of the collaboration, new developments on sensors, on mechanics (new directions for module construction, large support structure, cooling, and alignment and integration issues), new lab test bench results on electronics and sensors. The perspectives over a period of four years are presented with a detailed test beam schedule and the roadmap including the construction of new mechanical prototypes equipped with front end and readout chips in deep sub-micron CMOS technology are discussed. Combined tests with other sub-detectors are finally addressed. This test beam program is inserted in the framework of the EUDET European project. on behalf of the SiLC R&D Collaboration