Uses and limitations of quantitative structure-activity relationships (QSARs) to categorize substances on the Canadian domestic substance list as persistent and/or bioaccumulative,and inherently toxic to non-human organisms

Under sections 73 and 74 of the revised Canadian Environmental Protection Act (CEPA 1999) , Environment Canada and Health Canada must "categorize" and "screen" about 23,000 substances on the Domestic Substances List (DSL) for persistence (P), bioaccumulation (B), and inherently toxic (iT) properties. Since experimental data for P, B and iT are only available for a few DSL substances, a workshop was held to address issues associated with the use of Quantitative Structure-Activity Relationships (QSARs) to categorize these substances. This paper describes the results of an 11-12 November 1999 International Workshop sponsored by Environment Canada to discuss potential uses and limitations of QSARs to categorize DSL substances as either persistent or bioaccumulative and iT to non-human organisms and to recommend future research needed to develop methods for predicting the P, B and iT of difficult-to-model substances.     

矿井突水危险性评价模型

用数量化理论 (Ⅱ) 〔1〕研究了矿井突水危险性评价问题, 建立了一个实用的矿井突水危险性评价模型, 为煤矿安全评价开辟了一条新途径。     

基于投影寻踪的有机废弃物堆肥水溶性有机物荧光特性评价

水溶性有机物荧光特性是评价有机废弃物堆肥腐殖化程度的重要手段之一。针对现有方法大都局限于腐殖化程度的定性表征等问题,基于投影寻踪方法,该研究开展了堆肥腐熟程度分级评价的定量表征。通过对不同来源有机废弃物堆肥过程中样品水溶性有机物(DOM)荧光特性参数获取,采用统计分析表明,荧光参数I₄₃₆/I₃₈₃,FLR,P_HA/Pro,A₄/A₁,r_(A,C)两两之间显著相关(p<0.01),可作为综合评价指标。在此基础上,确定完全腐熟(Ⅰ级)、较腐熟(Ⅱ级)、基本腐熟(Ⅲ级)、未腐熟堆肥(Ⅳ级)4个腐熟等级荧光参数取值区间。模型运算得到各等投影值分别为2.01～2.22(Ⅰ级)、1.21～2.0(Ⅱ级)、0.57～1.2(Ⅲ级)、0.10～0.56(Ⅳ级)。模型验证证实,各样品的实际腐熟度等级与模型所得到腐熟与未腐熟样品的评价结果准确率为100%,因此,该评价方法对有机废弃物的实际堆肥具有重要的指导意义。     

基于模糊理论的软件寿命周期费用评价模型

软件寿命周期费用评价模型涉及到软件开发、使用和维护过程中各种资源最有效利用的权衡分析。由于软件开发不是一门严谨的精确科学,往往存在大量具有不确定性的需求以及许多未知和不确定因素,所有这些都给软件寿命周期费用评价带来模糊效用。本文将模糊理论应用于软件寿命周期费用的评价,给出了从评价属性模糊值的确定、模糊评价模型的建立,到模型求解和最优方案选择的模糊评价方法,并通过对一个算例的分析,证明了该模型的可行性。     

An Overview of Social Participation in Older Adults: Concepts and Assessments

In older adults, social participation is an important component of rehabilitation and health promotion. Several studies have attempted to describe the definition and concepts of social participation, and there were many outcomes to measure social participation. This overview provides information about representative social participation and related concepts that have been defined in the literature. A standardized definition of social participation has not been developed; commonly, recognition for social participation was proposed as focused on involvement in social activities that provide interaction with others in a society or community. Many instruments assess the various aspects of social participation. Because of operational definition and diversity in social participation, performance in social participation was adopted as an aspect of assessment. Further discussions are needed to clarify the definition of social participation and evaluate the instruments used to assess social participation for it to be useful for rehabilitation and health promotion. In doing so, determining and developing assessment and intervention based on the purpose or perspective of social participation in older adults with and without disabilities is important.     

Measurement uncertainty in analytical methods in which trueness is assessed from recovery assays

We propose a new procedure for estimating the uncertainty in quantitative routine analysis. This procedure uses the information generated when the trueness of the analytical method is assessed from recovery assays. In this paper, we assess trueness by estimating proportional bias (in terms of recovery) and constant bias separately. The advantage of the procedure is that little extra work needs to be done to estimate the measurement uncertainty associated to routine samples. This uncertainty is considered to be correct whenever the samples used in the recovery assays are representative of the future routine samples (in terms of matrix and analyte concentration). Moreover, these samples should be analysed by varying all the factors that can affect the analytical method. If they are analysed in this fashion, the precision estimates generated in the recovery assays take into account the variability of the routine samples and also all the sources of variability of the analytical method. Other terms related to the sample heterogeneity, sample pretreatments or factors not representatively varied in the recovery assays should only be subsequently included when necessary. The ideas presented are applied to calculate the uncertainty of results obtained when analysing sulphides in wine by HS-SPME-GC.     

建筑场地地震液化危害评价及地基处理

本文分析了地基失稳，计算震陷值及差异震陷等地基失效形式和液化土层的隔震作用，研究了液化指数、地基失效、液化土层隔震与多层房屋震害的关系，根据液化土的双重作用原理划分了液化危害等级，并提出了建筑场地地震液化危害评价方法和按“小震不坏，中震可修，大震不倒”的抗液化处理原则。     

Validating a concept inventory for measuring students’ probabilistic reasoning: The case of reasoning within the context of a raffle

Assessing students’ conceptions related to independence of events and determining probabilities from a sample space has been the focus of research in probability education for over 40 years. While we know a lot from past studies about predictable ways students may reason with well-known tasks, developing a diagnostic assessment that can be used by teachers to inform instruction demands the use of familiar and unfamiliar contexts. This paper presents the current work of a research team whose aim is to create a formative concept inventory with strong evidence of validity that uses a psychometric model to confidently predict whether a student exhibits one or more misconception across many items. We illustrate this process in this paper using a particular item with a context of a raffle aimed to measure whether a student reasons with misconceptions related to independence or equiprobability. The results of two aspects of the validity process: cognitive interviews to assess response processes on individual items, and a large-scale administration to examine internal structure of the concept inventory revealed difficulties in assessing students’ reasoning about these key probability concepts and trends in the prevalence of misconceptions across grades. Results can provide guidance for others aiming to develop assessments in mathematics education and also support further possibilities for research into understanding students’ reasoning about independence and sample space.     

基于功率转移函数的全光整形器性能评估

基于输入/输出功率转移函数的线性化三段模型,考察了全光整形器性能的理论评价方法,通过构建一个光纤四波混频整形仿真系统,验证了这种方法的合理性.分析了高斯分布的输入信号对全光整形器输出性能的影响.根据输入信号特性,将转移函数曲线由低到高分为五个区域,当信号"1"的均值落在第五区域时可获得较高的品质因数值和误码率性能的提升.最佳工作状态下,随着转移函数中间段斜率的增加,全光整形器输出信号品质因数值和误码率性能的提升会趋于饱和,但消光比有一个线性的增加.     

基于LS-DYNA的车辆碰撞数值分析

本文基于中国新车评估规程,对高速车辆正面相撞和高速测试车辆与静态车辆侧面相撞这两种工况进行了碰撞数值模拟,采用HYPERMESH进行建模和LS-DYNA进行仿真分析计算.分析结果表明,在正面碰撞中,前保险杠与阻挡壁接触发生弯曲和变形,随着碰撞时间的持续,发动机的副车架弯曲,导致乘客舱的侵入量明显增加.侧面碰撞中,B柱和测试车辆的蜂窝结构发生严重变形,发动机舱结构的褶皱吸收大量的冲击能量.通过改进车辆结构,A柱的侵入量从80 mm减小到40 mm,脚部空间的侵入量从210 mm减少到150 mm.侧面碰撞时B柱的窗口边缘处的侵入量与下部的侵入量也均满足安全要求.