Mechanical Characteristics of Radial Magnetic Bearing

1 IntroductionThe great majority of docUments about magneticbearings dealt only with the characteristics when thejournal was concentric with the radial magnetic bearing inthe past, and few research involved the ones when thejournal was eccotic with the radial magnetic bearing.For example, the bulk of documents suPPosed thecomponents Fx and F. of magnetic force depended onlyon the cUrred in x and y direchons respeGtively, bac theair gap thickness and the curvatUre of suiface shape werenot co…     

轮胎侧偏刚度对车辆操纵稳定性影响的分析

车辆操纵稳定性对控制车辆不足转向和过多转向具有重要的意义,对车辆运动的稳态响应和稳定性都十分重要。轮胎侧偏刚度对车辆操纵稳定有着直接或间接的影响．具有不同特性的车辆将表现出与其相对应的瞬态操纵稳定特性。本文通过前后轮胎侧偏刚度对车辆的操纵稳定性进行简要的分析。     

The relationship between mechanical stiffness and athletic performance markers in sub-elite footballers

This study investigated the relationship between several measures of lower-body stiffness and physical performance variables in 22 sub-elite male football players (mean ± SD; 21.9 ± 1.5 yr; 1.79 ± 0.06 m; 72.2 ± 7.2 kg). The participants were assessed for individual muscle stiffness of the Rectus Femoris (RF), Biceps Femoris (BF) and Medial Gastrocnemius (MG) muscles and vertical stiffness (Kvert) was also assessed assessed running acceleration, maximal sprint speed, agility, vertical jumping and muscular strength. Pearson’s correlations quantified the relationships and participants were also separated into relatively stiff (SG) and compliant groups (CG) for each variable. When ranked by Kvert the SG exhibited superior performance during sprinting, agility, jumping and strength (p ≤ 0.05) and when ranked by RF stiffness, SG exhibited superior sprint, agility and drop jump performance (p ≤ 0.05), while MG and BF stiffness were not related to performance. Higher stiffness appears to be beneficial to athletic performance for football players and therefore it may be beneficial for practitioners working with athletes that are required to perform dynamic activities to consider the contribution of stiffness to athletic performance.     

斜齿轮副结构参数灵敏度分析

以机械传动系统中的斜齿轮啮合为研究对象,在考虑时变刚度、齿侧间隙和啮合误差的情况下,建立了十自由度斜齿轮非线性振动数学模型。以斜齿轮结构参数作为灵敏度分析参数,采用数值分析方法分别研究了斜齿轮系统振动加速度均方根值对齿轮质量、支撑刚度和支撑阻尼的灵敏度。结果表明:主、被动轮横向（y向）振动对各参数敏感度较低,横向振动（x向）与被动轮扭转振动对质量参数、刚度参数、阻尼参数较为敏感,被动轮扭转振动受到阻尼的影响很大,灵敏度在扭转振动固有频率处变化较大。     

钢管混凝土格构式梁桥设计参数抗震研究

以三跨一联钢管混凝土格构式高墩连续梁桥为研究对象,探讨了梁墩刚度比、缀管布置形式和有无减隔震装置设计参数对格构墩地震响应（墩底轴力、墩底弯矩和墩顶位移）的影响规律。研究结果表明:随着梁墩刚度比值的增大,桥墩的地震响应值先急剧下降之后逐渐趋于平缓减小;缀管布置形式参数对格构墩的弯矩响应值影响较为敏感,而轴力和位移值受其影响较小;减隔震装置对该类桥梁的隔震效果显著,隔震率随梁墩刚度比值的增大而减小。设防烈度等级越高,轴力隔震效果越明显,弯矩和位移的隔震率受设防烈度等级影响较小。该研究可为同类桥梁抗震概念设计提     

K型铸钢节点刚域研究

本文利用ANSYS对K型铸钢节点与钢管相贯节点在节点转动刚度上进行了对比,K型铸钢节点存在刚域,既不是铰接,也不是简单刚接,本文提出了一种计算K型铸钢节点刚域长度的方法。     

肌肉的弹性与测量

根据由物体－弹簧和粘带器组成的系统作自由振荡时，其振荡频率是弹簧的弹性刚度和粘滞器粘滞系数等参量的函数的原理，介绍了一种简便易行的测量人体活体肌肉弹性的方法。由计算得知，在低负载时，肌肉张力是决定肌肉弹性刚度大小的主要因素；但随着负载的增加，肌肉的总弹性刚度趋向于由肌腱的弹性刚度来决定。     

Influence of aerobic treadmill exercise on blood glucose homeostasis in noninsulin dependent diabetes mellitus patients

The role of treadmill exercise on blood glucose homeostasis in noninsulin dependent diabetes mellitus (NIDDM) were studied using males between age of 45 and 60 years (X-52), who were clinically and biochemically-confirmed cases of NIDDM were taken into study group. Control group comprised of 10 males between age group of 45 to 60 (X-53) years. All the subjects were assessed by physician and were investigated to confirm diabetic status. The whole study period was extended for 6 weeks. The significant decrease in postprandial blood sugar (44.4 mg% for the study group and 32.2mg% for the control group) with a significant inter group difference (P<0.05) was observed. The mean decrease in fasting blood sugar (39.4mg% for the study group and 27.4mg% for the control group), with a marginal inter group difference (P<0.05) was observed. The treadmill exercise was found to be a definite tool in addition to drug and diet in glycemic control.     

Association between non-alcoholic fatty liver disease and arterial stiffness in the non-obese,non-hypertensive,and non-diabetic young and middle-aged Chinese population

Background and objective: Non-alcoholic fatty liver disease (NAFLD) is associated with arterial stiffness in the general population. Age, obesity, hypertension, and diabetics are risk factors for arterial stiffness. In this study, we aimed to investigate the association between NAFLD and arterial stiffness as measured by brachial-ankle pulse wave velocity (baPWV) in the non-obese, non-hypertensive, and non-diabetic young and middle-aged Chinese population. Methods: A cross-sectional study with 1296 non-obese, non-hypertensive, and non-diabetic young and middle-aged (20–65 years) subjects undergoing routine medical check-ups in the International Health Care Center of the Second Affiliated Hospital of School of Medicine of Zhejiang University was carried out. Fatty liver was diagnosed by ultrasonography, and baPWV was measured using an automatic waveform analyzer. The subjects were classified into two groups according to the presence of NAFLD, and divided into a further two groups according to their baPWV. Results: The overall incidence of NAFLD was 19.0%, and NAFLD patients had a significantly higher level of baPWV than the controls ((1321±158) cm/s vs. (1244±154) cm/s; P<0.001). The incidence of NAFLD was clearly higher in the increased baPWV group than in the normal baPWV group (29.3% vs. 16.9%; P<0.001), and the incidence increased in line with the increase of baPWV quartiles in the normal range as well as with the severity of arterial stiffness (both P for trend <0.001). Multiple linear logistic regression analysis showed that the presence of NAFLD was positively and independently associated with baPWV. Conclusions: Our results suggest that the presence of NAFLD is associated with arterial stiffness as measured by baPWV in the non-obese, non-hypertensive, and non-diabetic young and middle-aged Chinese population.     

复合材料层合板阶梯式挖补修理的刚度分析

基于有限元方法,利用有限元分析软件MSC.Patran/Nastran,建立复合材料层合板阶梯式挖补修理三维有限元模型,采用相对刚度分析方法,得出不同挖补阶数和胶层厚度对复合材料层合板阶梯式挖补修理结构刚度的影响规律.