EVALUATION OF THE CARCINOGENIC RISK OF BIOCHEMICALLY INERT INSOLUBLE PARTICLES BY THE EPA USING RAT INHALATION DATA

Regulations pertaining to inhalable particulate matter are promulgated primarily by three program offices of the U.S. Environmental Protection Agency (EPA): Pollution Prevention and Toxic Substances (OPPTS), Air Quality Planning and Standards (OAQPS), and Mobile Sources (OMS). Risk assessment for these agents are carried out either by the program offices or by the National Center for Environmental Assessment (NCEA), formerly the Office of Health and Environmental Assessment (OHEA). Particular matter pollutants within the regulatory domain of OAQPS for which either quantitative or qualitative assessment of cancer risk has been carried out include asbestos, beryllium, cadmium, nickel refinery dust, nickel subsulfide, and ambient particulate matter of less than 10 µm diameter (PM10). OPPTS has qualitatively evaluated manmade mineral fibers, titanium dioxide, and vermiculite. Asbestos is the only fiber for which cancer quantitation has been carried out. For several of these agents, risk is based upon human data with animal studies providing supporting data. Both qualitative and quantitative assessment of cancer risk from exposure to diesel engine emissions is under development by NCEA for OMS. Quantitative assessment of cancer risk from exposure to this agent is described as an example of EPA's approach to the use of rats for evaluation of cancer risk. The major uncertainties relating to this assessment include the appropriateness of rat data for assessing human risk and the selection of a low-dose extrapolation model.     

运用振动反分析方法计算振动荷载

本文研究运用振动反问题理论求解振动荷载时程的问题。在Newmark法求解运动平衡方程的基础上，推导了求解振动荷载的公式。采用最小二乘法估计最可置信的荷载系数。提出了由结构对振动荷载的反应求振动荷载时程的有限元方法。通过算例验证了方法的有效性。本文为计算振动荷载提供了一种新的方法。     

CALIBRATION OF SPHERICAL PARTICLES BY LIGHT SCATTERING USING PHOTON CORRELATION SPECTROSCOPY

Photon Correlation Spectroscopy, also known as Quasi-Elastic or Dynamic Light-Scattering, can be a convenient method of size measurement for suspensions of monodisperse spherical particles in the 20-500 nanometer (nm) size range [0.02 to 0.5 micrometer (μm)]. The results obtained vary widely, depending on the concentration and condition of the sample, as well as environmental factors. Techniques have been developed that improve the accuracy and precision of the measurements. These techniques include controlling the concentration, uniformity and dispersion of the sample. The improved method was verified by measuring particle-size standards.     

用桩顶脉冲响应信号估计基桩桩身形状

本文提出了一种用实测桩顶脉冲响应信号估计基桩桩身形状的方法，该方法能定量确定桩身缺陷的位置、延伸范围以及严重程度。文中给出了两根模型桩桩身形状估计的应用实测。     

基于监测数据的结构地震损伤追踪与量化评估方法

基于延性的工程抗震设计允许结构在强地震作用下进入非线性,即允许结构产生地震损伤。从物理和力学的角度,抗震行为模拟与性态评估一般考虑地震损伤的峰值效应和累积效应。但是,由于先验性知识(如滞回耗能、承载力与变形能力)的限制,抗震研究中广泛应用的Park-Ang损伤模型较难直接用于大型在役结构的地震损伤评价。受到控制领域模型参考思想的启发,该文提出一类基于数据驱动的损伤评估模型,能自适应于不同的受力状态与破坏模式,实现综合评估震损结构峰值和累积损伤效应。利用美国NEES计划公开的足尺钢筋混凝土(RC)柱动力试验数据,研究了所提出数据驱动损伤指标与RC柱地震损伤发展的相关性与时域追踪效果,验证了评估指标能有效区分RC柱水平侧移与弯曲变形相应损伤的发展与累积差异。此类基于模型参考思想的新型损伤评估指标,不需要提前获知结构非线性特征和计算滞回耗能,可应用于基于强震观测的工程结构抗震性态评估。     

通过可控微乳液聚合制备聚苯乙烯超微粒子

初步研究了苯乙烯的反向原子转移自由基微乳液聚合．探讨了盐的同离子效应对提高反应可控性的作用和通过可控微乳液聚合制备聚合物超微粒子的可行性．研究结果表明．控制AIBN／CuCl2／bpy的摩尔比和在聚合体系中加入少量小分子电解质NaCl,均可提高反应的可控性;通过微乳液条件下苯乙烯的反向原子转移自由基聚合可以获得聚苯乙烯超微粒子．     

ANALYSIS OF FATIGUE LIFE DATA USING THE BOX-COX TRANSFORMATION

Fatigue life data customarily analyzed using the logarithmic transformation may be better analyzed using the Box-Cox transformation. This transformation has the advantages of stabilizing the variance, simplifying the model and transforming to approximate normality. In addition, simple schemes for imputing run-outs can be constructed and the endurance limit can be easily calculated. This paper considers in detail the use of the transformation on fatigue life data from a thick plate Al-Zn-Cu-Mg alloy. It presents a simplified method for determining the transformation, and then uses the transformation to determine distinctions in quality between different lots and confidence intervals on the lifetime.     

ESTIMATION OF THE AVERAGE ASPECT RATIO OF LAMELLAE-SHAPED PARTICLES BY LASER DIFFRACTOMETRY

Reinforcing properties for polymers and elastomers, rheological properties of high density aqueous slurries, hidding power, lubricating properties of platey particles strongly depend on their size distribution and shape factor or aspect ratio (A.R.).

Determinations of A.R. of fine particles by conventional methods are time-consuming and require sophisticated equipment. A method based upon later light diffractometry has been developed to meet control requirements in industry, the average A.R. can be determined within 5 to 10 minutes, depending upon the number of measurements made using a commercial laser granulometer.

The method relies on:

a cylindrical model (disc) of platey particles.

determinations of the projected area of particles in dilute suspensions of controlled solids concentrations.

calibration of the instrument, using isodiametric particles

simple material balance to derive the average thickness h of the platey particles from projected area measurements and volume of the solid.

A.R. is defined as d50(S)/h. where d50(S) is the mean projected area diameter and h the average thickness attributed to all particles occurring in the sample.     

用正弦波拟合法评价数据采集系统的通道间延时

本文介绍了数据采集系统通道间延时的一种简单实用的评价方法,讨论了评价过程的误差来源,以及减小其评价误差的几种对策;同时,给出了评价过程的计算机仿真结果。     

COAGULATION OF SUSPENDED PARTICLES BY BROWNIAN MOTION FOR THE QUASI-SELF-PRESERVING CASE

An analytic solution is developed for the aerosol coagulation problem in the transition regime. The size distribution of a coagulating aerosol is represented by log-normal functions and particle size distribution is assumed 10 pass through a series of quasi-self-preserving size distributions. The effects of Knudsen number on the Brownian coagulation are discussed along with the results. It is confirmed that after a sufficient period of elapsed time, a self-preserving log-normal size distribution develops whose geometric standard deviation remains unchanged. Such a distribution is found to be narrower than that for the continuum regime and depends upon the Knudsen number. It is shown that the current model serves as the upper bound for the transition regime coagulation problem while the continuum regime constitutes the lower bound. Good agreement was obtained when the present analytic solution was compared with existing numerical studies on transition regime coagulation for the regime up to the Knudsen number of about 1.     

扫描电镜测量微米级长度的不确定度评定

对扫描电镜测量微米级长度的不确定度进行了评定。对引起不确定度性的许多因素，如扫描电镜的分辨率、测量的重复性以及标尺的标定误差等作了分析和计算，特别对输入变量相关时的合成问题作了研究。最后得到了S-4200型扫描电镜微米级测量长度的不确定度。     

ATRP法合成PMMA-b-PS-b-PFx-14三嵌段共聚物

首先通过原子转移自由基聚合(ATRP)得到了末端含卤素的聚甲基丙烯酸甲酯，以这种PMMA为大分子引发剂，引发苯乙烯的ATRP反应，得到了末端含卤素的PMMA-PSt双嵌段共聚物。再以这种双嵌段共聚物大分子为引发剂，引发含氟丙烯酸酯Fx-14的ATRP反应，得到了一种PMMA-PSt-Fx-14三嵌段共聚物．通过GPC、核磁、粘度等数据证实了该聚合物的结构，并详细讨论了由于PMMA-PSt-Fx-14在溶液中的线团行为所产生的GPC测试中出现的特殊现象。     

应用局部应力-应变法计算联轴器膜片疲劳寿命

由于轴线间的角向不对中,联轴器旋转时膜片中产生交变应力,引起疲劳问题。使用中需要考虑其疲劳寿命。本文对六孔圆环形和束腰形膜片,利用有限元方法和薄板弯曲理论建立膜片应力计算模型。引入改进的局部应力－应变法,建立计算膜片联轴器膜片疲劳裂纹形成寿命的模型和方法。定量分析两种形式膜片的应力、附加载荷和疲劳寿命,最后,得出对膜片组设计有参考价值的结论。结论表明,对于设计合理的膜片,其疲劳寿命能满足机组工作要求。     

洁净系统中激光诱导颗粒污染物的分析与评估

高功率激光系统要求在洁净环境中运行,若光学元件表面在工作过程中附着污染物,将导致光学元件的损伤及整个系统负载能力的下降。针对洁净系统中激光与材料作用而产生的颗粒物,分析其作用机制,探讨用于评估的理论依据,讨论测量的需求和方法,并对系统表面存在的颗粒污染物进行了实际测量分析,提出了深入开展高功率激光系统中颗粒污染物测量与评估的技术途径。     

基于地震损失风险钢筋混凝土框架结构弯矩增大系数评估

损失是表征结构性能的综合指标。为了从损失风险的角度评估现行抗震规范钢筋混凝土框架弯矩增大系数的取值,基于地震风险评估框架FEMA P-58,给出了基于结构整体易损性分析的地震损失计算方法。设计了4个弯矩增大系数分别为1.1、1.3、1.5、1.7的钢筋混凝土框架结构,采用增量动力时程分析方法,得出了结构的易损性曲线和易损性矩阵,按照地震烈度概率模型,给出了所在场地各种烈度地震发生的概率,计算了每个结构在50年和1年内的经济损失和人员伤亡损失。结果表明,地震损失风险随强柱弱梁系数增大而减小,50年总经济损失比介于0.08~0.12,人员损伤率介于4.85×10^-4~1.12×10^-3。按照目前规范取值设计的结构地震损失风险处于可接受范围内。     

THE DETERMINATION OF HYSTERESIS LOOPS IN THERMO-MECHANICAL FATIGUE USING ISOTHERMAL STRESS-STRAIN DATA

Abstract— Thermo-mechanical fatigue stress-strain data on ferritic/austenitic steels and superalloys from a variety of sources are analysed with regard to hysteresis loop stress asymmetry. This arises from a decoupling of the thermal and mechanical strain signals in the test technique so that many tension-compression load combinations are possible. Data from simplified isothermal and bithermal tests are also examined. Taking a typical example of an "out-of-phase" thermo-mechanical loop on a 1/2 CrMoV steel cycled between 200 and 550°C, isothermal stress-strain data were generated at 50°C intervals on material from the same cast and, used in conjunction with the elastic characteristics of the apparatus, an attempt was made to re-create this loop. The methods employed were (i) a graphical construction between appropriate isothermal yield contours (ii) a tangent modulus calculation (iii) a secant modulus calculation. Method (i) appeared to give the closest agreement in the present case.     

碳纤维碳化特征的SAM微观分析

本文应用SAM方法检测了由不同工艺条件造成的碳纤维的污染和产生的缺陷。对任意一根碳纤维,其表面和内部的碳俄歇峰、峰高和峰形都有差异,这一差异导致碳沿径向分布不均匀,并影响到碳纤维的力学性能。采用SAM的方法可监测予氧化和碳化过程中的工艺参数以便提高碳纤维的质量。      

一位码纠错编码器的可编程逻辑器件实现

纠正数字信号在传输中出现的差错,逐渐成为数字通讯系统中的一个突出问题,这就要求采取适当的编码方法,及时发现并纠正错误,来提高信息传输的可靠性。本文简单介绍了用（１２,８）码纠正一位错误码元的原理;详细讨论了用一片Ｌａｔｔｉｃｅ ｉｓｐＬＳＩ１０１６芯片实现（１２,８）码编码器和解码器的设计方法。     

无机超细粒子表面聚合物包覆改性研究进展

文中就聚合物对无机粒子表面进行包覆改性的原位聚合方法,包括接枝聚合法和乳液聚合法的研究现状进行了综述。介绍了接枝聚合法中的预先接枝不饱和基团、预先接枝引发基团以及预先接枝终止基团等方法和乳液聚合法中的无皂乳液聚合法、预处理乳液聚合法以及微乳液聚合法等方法,并分析了它们对无机粒子进行表面改性的优劣。