Spatio-temporal patterns in county-level incidence and reporting of Lyme disease in the northeastern United States, 1990–2000

We present an exploratory analysis of reported county-specific incidence of Lyme disease in the northeastern United States for the years 1990–2000. We briefly review the disease ecology of Lyme disease and the use of risk maps to describe local incidence as estimates of local risk of disease. We place the relevant elements of local environmental and ecological variables, local disease incidence, and (importantly) local disease reporting in a conceptual context to frame our analysis. We then apply hierarchical linear models of increasing complexity to summarize observed patterns in reported incidence, borrowing information across counties to improve local precision. We find areas of increasing incidence in the central northeastern Atlantic coast counties, increasing incidence branching to the north and west, and an area of fairly stable and slightly decreasing reported incidence in western New York.     

弯曲线不重合V形件的模具设计

弯曲线不重合且其精度要求较高的V形件的弯曲,是一较为棘手的问题。本文介绍了一种利用顶板侧壁的斜面,迫使下模框内摆块转动,从而克服工件回弹,并确保弯曲精度的V形弯曲模的设计。     

亚洲地区环境监测实验室精度调查

为了解亚洲各国环境监测实验室监测分析数据的精度现状,提高实验室的监测技术水平,同时为了编制“亚洲地区环境监测实验室精度管理手册”提供依据,日本JICA（日本国际协力团）在亚洲开展了精度调查工作。文章报导了我国有关的33个环境监测实验室参加该精度调查的内容,和本次精度调查的结果及影响数据质量的因素分析,并与亚洲其它国家精度调查结果进行了比较。     

铬酸钡光度法测定硫酸盐的改进研究

铬酸钡光度法是测定水中硫酸盐的常用方法之一，但是因为过滤法本身的粗糙使得检测结果重现性差、准确率低。为了提高该方法的准确度和精密度，现用离心机分离代替实验中过滤分离沉淀。实验表明离心机分离法线形范围0～200mg/L，回归方程：y=0．1129x-0．0030，γ=0．9992，检出限为7．10ng/L，回收率约96％～104％，相对标准偏差（RSD）为0．45％．2．37％，结果无显著性差异（t=0．24，P〉0．01）。该方法可应用于水中硫酸盐含量测定以提高准确度，方法快速简便，并与标准方法（重量法）比较，结果满意。     

一种基于离心机试验辨识惯导平台误差系数的方法

针对离心机试验中惯导平台误差系数辨识问题,提出了一种基于谐波分析辨识误差系数的方法。首先,根据惯性器件误差模型推导了离心机试验下陀螺和加速度计的输出方程,其输出由各阶谐波分量构成。然后通过傅里叶分析得到各项谐波的幅值。最后根据谐波幅值与各项误差系数之间的关系反解得到各项误差系数。仿真结果验证了方法的有效性。     

惯性系统飞行试验精度检验方法

目的针对传统工具误差分离方法得到的分离结果不够准确可信的问题,提出了一种利用等效误差实现对惯性系统精度判定的方法。方法首先基于主成分分析,定义等效误差,等效误差具有独立、无偏的性质。然后提出基于等效误差的假设检验判断惯性系统精度是否合格的方法。结果算例表明采用该方法可以实现惯性系统精度的可信判断。结论该方法解决了以往方法误差大,分析结论可信度不高的问题。     

Influence of disability type on upper-limb motor skills

This study was carried out in order to determine the effect of physical disability (paraplegia) and sensory disability (deafness) on motor skills of the upper limbs. Studies were distinguished by two parameters: the nature of the control curve (sine or random) and the magnitude of the isometric force exerted on the lever (10?N, 20?N, 40?N, 80?N). A comparison of the quality of manual force control in a visual detection task among groups of people with sensory disability (deaf), people with physical disability (paraplegic) and people without disability showed differences among those groups. Values of force above 20?N create conditions of lower quality of control and of direction of force exertion outside the body. At the same time, the study proved that people with some types of disability can perform certain work tasks as effectively as people without disability.     

精密离心机静态半径测量不确定度的温度特性分析

目的研究温度对精密离心机静态半径测量不确定度的影响。方法以静态半径测量反算法为基础,推导静态半径测量不确定度的温度特性模型,设计精密恒温装置,并进行试验,获取加速度计在1 g离心机场下不同温度时的输出数据,并进行分析。结果基于温度特性模型,确定了影响静态半径测量不确定度的主要因素。试验数据结果表明,在加速度计工作范围内(50~60℃),静态半径测量不确定度随温度递增呈现“先增后减”的分布规律,且在50℃时进入到了10‒7量级。结论加速度计的温度敏感性是影响静态半径测量不确定度的最主要因素,精密控温能显著提高静态半径测量精度。     

CENTRIFUGE MODELING OF ONE-DIMENSIONAL SUBSURFACE CONTAMINATION1

ABSTRACT: One-dimensional contaminant transport through a saturated soil is modeled using a 1.2-m radius geotechnical centrifuge. Small-scale physical modeling in the centrifuge is achieved in relatively short time, at stress distributions that are similar to those experienced in the prototype (actual site). A 0.05 mol/l of sodium chloride solution is used as a contaminant and conductivity cells measure the concentration of the contaminant throughout the porous medium. Scaling analysis for centrifuge modeling and 1-g modeling are briefly discussed and it is concluded that centrifuge modeling simulates the effect of molecular diffusion; however, scaling of the effect of mechanical dispersion may be violated in the centrifuge if the interstitial fluid velocity is high. Centrifuge test results show good agreement with the predicted relationship between the coefficient of hydrodynamic dispersion and the Peclet number using column tests. Centrifuge modeling can be used as a complement of numerical modeling although the effect of mechanical dispersion may be overestimated in the former.     

突起路标合理设置的原理与方法研究

目前国内外还没有针对路钮的设置间距进行相关的模型研究,实施中通常根据经验进行设置。笔者基于曲线曲率最佳感知精度和路钮视像连续的两种设置原理,并考虑驾驶员的视觉特点、车辆的灯光照射性能,提出以视线诱导为目的,在驾驶员视野范围内始终出现4块路钮的设置间距与曲线半径的关系模型;并以路钮视像在人眼中形成一条连续的诱导线为目的设置间距与道路设计车速之间的关系模型。在两种方法的最终设置间距中取两种模型的小值作为最终的设置间距,并根据反光及不反光路钮的特点、设置的经济性和路段的交通安全状况对其设置方式作了分析和探讨。经研究,该模型可作为相关规范中路钮设置间距的依据。