航空发动机叶片扭转刚度试验装置误差评定

本文针对一种航空发动机叶片扭转刚度试验装置进行了误差评定,分析研究了误差减小与控制的方法。对扭转刚度公式展开误差传递函数分析,从载荷施加和角度测量两方面分析试验装置产生误差的主要因素,并采用误差传递函数进行合成,确定了扭转刚度的误差。通过对附加载荷等误差影响因素的深入分析,总结出试验过程中减小和控制误差的一般规律和方法。通过改进试验装置,将扭转刚度测量误差从±2.6%降低到±0.8%。建议叶片转动角度应控制在5°以内,以控制误差在合理范围。本文结果对工程实践有一定的指导意义。     

采煤机摇臂刚度和强度分析

本文用有限单元法分析滚筒采煤机的关键部件摇臂结构,探讨了它的计算模型,得到了多种工况作用下该结构的刚度和强度,由此得出一些结论以供设计时参考。     

三轴运动模拟台正弦失真的异步自学习控制补偿方法

本文分析了三轴运动模拟台的干摩擦特性,并提出利用作者给出的PID 型异步自学习控制解决由干摩擦非线性引起的正弦振动失真。仿真结果表明,利用此法可使相应的正弦振动精度高达10~(-3)数量级,可满足三轴运动模拟台伺服系统设计中的有关精度要求。     

International cooperation and networking in genetic health care provision: issues arising from the genetic services plan for the Emilia-Romagna region, Italy

The aims of this report are to describe the genetic plan for Emilia-Romagna, a region in Italy, and to contribute to the international exchange of information on developing and applying policy frameworks to provide high-quality and comprehensive genetic health care in the publicly funded health systems. At the present time there is no national policy for genetic medicine in Italy, and only two regions, Emilia-Romagna and Liguria, have formally agreed to a strategic plan for health care in genetics. The current provision of genetic services in Emilia-Romagna is described focusing on the intra- and inter-organizational linkages to ensure a comprehensive system of coordinated activities. Strengths and implementation areas are highlighted. Points that must be solved within the regional or national context are the definition of the level of assistance required in genetic medicine, the formal professional recognition of the genetic counselor and the adjustment of the billing mechanisms to the complexities of clinical genetic services. Issues that need to be addressed at a wider level include full assessment of genetic tests before their introduction into clinical practice, networking to provide tests for the rarest genetic diseases, consensus on fundamental terminology and clinical and administrative data sets to promote a cohesive framework for the flow of information throughout the health care systems with respect to genetics.     

What are gene patents and why are people worried about them?

This article examines what it means to patent a gene. Numerous ethical concerns have been raised about the effects of such patents on clinical medical practice as well as on research and development. We describe what kinds of inventions are covered by human gene patents, give several examples and summarize the small body of empirical research performed in the US examining the effects of these patents. There is little evidence that early fears about gene patenting placing substantial restraints on research and clinical medicine have come to fruition. Nonetheless, there are areas of concern, and policy makers, physicians and the public should be alert to ensure that the net social benefits of patenting human genes are maintained.     

弹性地基梁振动特性的近似分析方法

文中介绍了用模态摄动法分析复杂情况下弹性地基梁动力特性的近似方法。这一方法中可考虑纵向钢筋以及变地基弹性系数对弹性地基梁振动特性的影响，通过算例说明了这一方法的有效性。     

用偏振全息术分离绝对程差条纹

本文提出了一种利用偏振全息术以分离绝对程差条纹的新方法.此法只需一张两次曝光的全息图就能直接观察到两族绝对程差条纹及其迭加图案.若在全息图和观察者之间放置一线性偏振镜,当转动偏振镜时,还能观察到偏振镜的透射轴与一个主应力方向平行的那些点的绝对程差条纹,从而能在整个模型上精确地分离两个绝对程差条纹族.文中利用Jones 矢量和矩阵的运算,导出了通过偏振镜观察全息图时再现虚象光强的一般表达式,最后提供了实验证明.     

激波风洞中物体表面压力分布测量

本文介绍了激波风洞中模型表面压力分布测量工作中所碰到的有关技术问题。 文中用毛主席的《实践论》为指号,以我们实际工作中所碰到的问题为线索,以通俗的形式重点介绍了压电式压力传感器如何提高灵敏度和抗干扰的能力,制造中的有关技术,以及所配用的小型放大线路和传感器的标定技术,并给出了实验结果。文末对传感器的测量误差进行了分析和估计,并指出了进一步改进的问题。     

有限元法在三轴转台机械系统设计中的应用

本文探讨了三轴转台机械系统的设计与计算问题，以惯性三轴测试转台和三轴模拟台为例，确定了多种运转状态下的有限元法计算模型，并对其进行了静、动态特性计算，比较分析了计算结果，为合理结构的设计提供了重要数据，说明了在三轴转台机械系统设计中有限元法的重要性     

Marfan syndrome in Europe

OBJECTIVES: Marfan syndrome (MFS) is a relatively frequent systemic connective tissue disorder with an important physical morbidity and mortality. The influences of MFS on physical problems, perception of severity, and impact on the quality of life and psychosocial well-being have been studied only limitedly. The aim of this study was to assess the association between the severity derived from the reported symptoms and subjectively experienced severity of MFS (expressed as a global judgment), with special emphasis regarding impact on relationships and pregnancies, psychosocial adjustment, and differences between the seven European countries. METHODS: A questionnaire designed specifically for this study and translated in each of the native languages was sent to 2,080 members of one of the patient support groups in Belgium, Denmark, France, Germany, The Netherlands, Switzerland, and the United Kingdom. 857 MFS patients of 13 years and older completed the questionnaire and were included in the data analysis. RESULTS: Physical impairments were scored by perception of severity of physical symptoms by the patients (physical severity perception score) and by their perception of the influence of MFS on their life (subjective severity score). Main discrepancy between physical severity perception and subjective severity score was the higher percentage of patients scoring in physical severity perception as severe (53.5%) compared to subjectively severe (26.5%). 61% of those who scored on the physical severity score as severely affected were designated as being mildly-moderately affected on subjective scoring. Both severity scores increased significantly with age. Two hundred-twenty women have carried 430 pregnancies (1.95 pregnancies/woman), with cardiovascular complications in 1.6%. Prenatal studies for MFS were rejected by 7.6% of MFS patients of 25 years and older, 33.6% were undecided, and 48.5% favored prenatal diagnosis for MFS if available. A positive general self-image was reported by 91.5% of patients. However, more than 90% stated that MFS had a negative influence on their sexual relationships, which they ascribed to negative perception of their body image. CONCLUSIONS: MFS has significant impact on daily life activities, but the majority of patients come to terms with their condition. Acceptance is mainly determined by subjective severity, and less by physical symptoms as reported by the patients themselves. It is important to stimulate a positive attitude towards MFS.