摘要：The surface topography of acetabular implants plays a key role in providing cell attachment and *** measurement and characterisation of the surface texture of the cellular scaffold layer on the acetabular cup are very difficult due to the 3D nature of scaffold *** is proposed to use X-ray computed tomography(XCT)to measure the surface texture of an electron beam melting-produced titanium acetabular *** surface texture of its cellular scaffold is evaluated using the newly developed 3D surface texture parameters,which allows surface characterisation on 3D triangular mesh *** commonly used height parameters,*** arithmetical mean height Sa,the root mean square height Sq,the skewness Ssk and the kurtosis Sku,are calculated from surface patches extracted from the XCT scanned triangular mesh *** addition,the surface peak density and pit density,which are more related to cell communication and proliferation,are estimated based on the 3D watershed *** Wolf pruning with an empirical threshold 12μm is used to control the over-segmentation.

摘要：The meaning of advertising is generated through how audience perceive,observe,describe,and interact with *** advertising is not only a bare statement of fact,it is far from being a reliance on literal and *** the contrary,it is rather a combination of many types of concept communications,containing *** the emotion idea can be easily to elicit perceptions,interpretations,and the affective response of the consumers with regard to the information being *** key concept also facilitate the process of explicating different situational phenomena that demonstrate certain attitudes,beliefs,and values.

摘要：目的:通过引入坡变换,揭示表面测量中形态学操作的本质。创新点:引入坡变换,将空间域的形态学膨胀操作转换为坡域的加法操作,揭示结构元素对表面轮廓坡度和曲率的改变。方法:1.基于坡变换理论,空间域的切膨胀操作对应于坡域的加法操作(图9);2.分析圆结构元素作用于正弦波和圆的理论解;3.用不同半径的圆结构元素作用于正弦波,分析切膨胀和经典膨胀的相同和不同之处。结论:1.坡变换将形态学操作从空间域转换到坡域,可获取类似于傅立叶变换将卷积操作从空间域转换到频域的分析能力;2.切膨胀操作为经典膨胀操作的上确界,但会产生重叠区域。

摘要：This paper presents investigations into the influences of bearing clearances on the diagnostic features of monitoring rolling-bearings. A nonlinear dynamic model of a deep groove ball bearing with five degrees of freedom is developed for numerical analysis under increased radial clearances which are due to not only the scenarios of bearing grades but also gradual wear with bearing service lifetime. The model incorporates local defects and clearance increments in order to gain the insight into the bearing dynamics under different fault cases along with clearance changes. Numerical results show that the vibrations at fault characteristic frequencies exhibit clear inconsistency with common understandings for different cases of increased clearances. This study highlights that it has to take into account the clearance effect, especially for the inner race fault, in order to avoid the under-estimate of fault sizes which may be indicated by the feature amplitude reduction.

摘要：作为机械产品设计和制造过程中的一项重要内容,计算机辅助公差设计(CAT)是CAD/CAPP/CAM集成的关键技术,是国内外先进制造技术发展中亟需解决的问题。计算机辅助公差设计覆盖面非常广泛,涵盖公差规范和标准化、设计/制造工艺/产品生命周期管理中的公差设计、检测与测量以及功能公差设计。本文首先简要分析这些热点问题的研究进展情况,其次介绍本专辑收集的第13届国际生产工程科学院计算机辅助公差设计会议中的最新研究成果,分析该领域的最新研究进展,希望能帮助读者了解相关研究工作并促进研究人员开展讨论,进一步实现计算机辅助公差设计中的关键技术的突破,促进CAD/CAPP/CAM的集成。

摘要：几何要素是构成工件几何特征的点、线和面。研究了新一代产品几何量技术规范(GPS)中几何要素的术语、定义、分类以及它们之间的相互关系,介绍了几何要素的操作与操作算子等数学处理工具,并给出了在产品设计、规范和认证过程中的应用。

摘要：Purpose:Wearable devices are commonly used to measure physical ***,it remains unclear the effect of wearing these devices on health *** aim was to provide evidence related to wearing physical activity trackers and health ***:A quantitative comparison study design was used comparing participants who wore physical activity tracking devices(n=108)and those who did not(n=112).A paper-based Physical Health Knowledge survey designed for the purpose of this research was used for data collection in ***:A difference between participants who wore physical activity tracking devices and those that did not was identified in relation to activity levels and physical health *** devices are suggested as an opportunity for nurses to engage people in physical activity with the potential to improve their health ***:Nurses are well placed in the healthcare landscape to work with patients who own an activity tracker device concerning increasing activity *** information the patient has from the device can also form the basis of health discussions between nurses and the people in their care.

摘要：基于Shercliff权函数提出区域权函数概念,设计多电极电磁流量计,通过测量管道截面不同位置的弦端电压,计算各区域的轴向平均速度,实现速度分布与体积流量的测量。着重研究了流量计电极设计,选取不锈钢平头方案的多电极电磁流量计,对于阀门下游的非轴对称单相流体积流量测量精度高于±1.0%,倾斜管固—液两相流实验证明:该设计对于两相流非轴对称的速度分布测量具备可靠性。

摘要：针对滚动轴承振动信号的强非线性和非平稳特性,提出了一种基于改进集成经验模态分解(IEEMD)和调制信号双谱(MSB)分析的故障特征提取方法。将集成经验模态分解(EEMD)应用于滚动轴承的振动信号处理,将其分解成一系列的本征模态函数(IMFs);通过累计均值(MSAM)准则将IMFs自适应地分为低频IMFs和高频IMFs,其中高频IMFs采用小波阈值降噪进行处理;将降噪后的高频IMFs与低频IMFs进行重构以获取高信噪比的瞬态脉冲信号;利用MSB进一步抑制瞬态脉冲信号中的随机噪声和干扰分量,并提取信号故障特征。与谱峭度(SK)和WEEMD-MSB分析结果进行对比,验证了该方法在轴承微弱故障特征提取方面的优越性。

摘要：针对故障轴承的振动信号中包含冲击成分,导致信号的能量集中的问题,提出了一种基于小波包能量与峭度谱相结合的方法用以提取轴承故障信号特征。首先应用小波包对测量信号进行分解、能量归一化处理和信号重构,然后将重构信号采用峭度谱确定带通滤波器的最佳中心频率和带宽,最后将滤波信号进行包络解调并提取故障特征频率。分别对仿真信号和试验数据进行研究,能够清晰地得到故障特征频率及其高次谐波,从而验证了所提方法在滚动轴承的故障诊断中的有效性和可行性。