共查询到20条相似文献，搜索用时 15 毫秒
1.
This paper presents surface modifications of aluminum-alloy induced by laser-shock processing (LSP). In the first part, the basic principles are discussed to provide an overview of the physical processes involved in laser shock processing, and to introduce pressure loadings generated by different laser generators. In the second part, emphases are given to the effects of laser intensity, target material, laser pulse duration and laser wavelength, and uniform and localized modeling of fatigue behavior after LSP. In the third part,experimental results are given to show the laser-induced pure mechanical effects on aluminum-alloy by using LSP. 相似文献
2.
光栅衍射型激光告警机是利用激光通过光栅后成像在光电探测器上的衍射条纹,进行分析处理而得到激光参数的。在其工作波长范围内太阳光线等背景噪声很严重。这些噪声使还原和检测探测信号的过程十分复杂、缓慢,甚至不精确。本文设计的系统通过两台同步CCD撂潮器,一台配有光栅,将获得的图像相减处理,快速减少噪声干扰,识别探测信号光斑。再根据光斑位置和面积用最小的矩形将光斑固住,光滑处理后,根据边缘点椭圆测试得到椭圆的中心,即各个光斑精确的坐标。这种设计可以使激光告警机的后期处理更加快速、高效、准确。 相似文献
3.
激光光斑中心的精确定位是机器视觉检测领域的关键技术。本文就双摄像头获取的十字激光图像进行光斑中心检测。首先,根据激光光斑亮度高的特点,以最大类间方差法对激光图像进行二值化处理,既可以简化后续处理、提高实时性,又可以排除背景中的各种干扰因素。然后分别检测两条激光中心线点群作为直线拟合的样本点,并采用最小二乘算法拟合两条激光线得到激光光斑中心的亚像素级定位。最后,对得到的激光光斑中心进行分析,去除由于物体表面不光滑等因素产生的干扰线对检测结果的影响。实验结果表明该算法能够满足实时性需求,鲁棒性好,定位精度高。 相似文献
4.
赵升升 《深圳职业技术学院学报》2013,12(3):64-69,74
文章讨论了几种薄膜残余应力测试方法的优缺点,介绍了氮化物薄膜应力沿层深分布趋势的最新研究,偏压和N2分压工艺对薄膜应力的影响及几种调节薄膜残余应力的有效方法．脉冲偏压增大,薄膜残余应力显著增加：N2分压增大,薄膜残余应力显著增加．采用独立变化脉冲偏压或变化N2分压工艺制备的薄膜,其残余应力沿层深分布趋势明显均匀,薄膜残余应力可得到有效调整． 相似文献
5.
建立了模拟涂层残余应力的数学模型,对等离子喷涂不同厚度NiCrAl/Cr2O3-8%TiO2涂层的残余应力进行了模拟,模拟结果表明:由于涂层与基体的热膨胀系数不匹配等原因,在界面等区域存在严重的应力集中,涂层内部的残余应力水平,随涂层厚度增加而增加,涂层中的径向、轴向、切向应力均为压应力,径向应力是最主要的应力。 相似文献
6.
选择激光功率、扫描速度、送粉量为影响因素,用正交试验方法研究了不锈钢基体激光熔覆Ni60A的残余应力;结果表明:影响残余应力的关键因素为扫描速度,其次是激光功率,最后为送粉量;扫描速度180 mm/min、激光功率1.5 kW、送粉量3 g/s产生最小残余应力;此时熔覆材料Ni60A与基体形成良好的冶金结合,熔覆层组织均匀,无微裂纹等明显缺陷。研究结果为叶轮和螺杆的激光熔覆再制造提供了实验依据。 相似文献
7.
针对因裂纹而导致失效的曲轴进行激光熔覆再制造,讨论了激光熔覆技术的具体工艺流程和工艺环境及激光熔覆材料的选择;运用ANSYS分析软件对修复后的零件进行温度场与应力场、3种熔覆层的残余应力的仿真分析,研究铁基、钴基、镍基自熔性合金粉末熔覆材料的修复结果,确定了基体材料45钢的曲轴单拐裂纹的最佳熔覆材料． 相似文献
8.
介绍了适用薄膜残余应力测量的弯曲法和X射线掠射法,重点介绍了一种新型测量薄膜残余应力的方法—纳米压痕法,并采用非球形压头纳米压痕法测量了NiTi薄膜的残余应力,对薄膜残余应力的测量进行了有益的探讨和尝试,结果表明纳米压痕技术可作为定性测量薄膜残余应力的有效手段。 相似文献
9.
本文讨论了激光扩展的机制问题,给出了短期和长期扩展光斑半径ps和PL的均方值的近似计算方法,提供了一套测量短期扩展效应的技术,进行了在静态空气、湍流空气和暖风场下光束扩展的测量,所得结果与理论值比较吻合,光束扩展谱的统计分布近似于正态分布。 相似文献
10.
王宁 《重庆职业技术学院学报》2003,12(4):96-97
风景区作为旅游产品,其本质是服务产品,风景区产品是一种经历。风景区产品的特性及其市场属性对风景区的营销有着重要的影响。风景区的营销必须以消费者(游客)的需要为导向,根据市场需求来制定其经营目标和策略,根据自身供给条件组织营销。其中的关键在于把握风景名胜区的产品特性和市场属性。 相似文献
11.
超短超强激光与物质相互作用产生的K-alpha线辐射,有准单能、发射区域小、时间短等优点,具有广泛的应用前景。介绍了超短超强激光辐照靶物质产生K-alpha源的基本原理及其主要研究内容,讨论了该领域的研究热点。 相似文献
12.
CAO Pin-lu LIU Bao-chang YIN Kun ZHANG Zu-pei 《浙江大学学报(A卷英文版)》2006,7(8):1318-1323
INTRODUCTION Polycrystalline diamond compacts (PDC), con-sisting of a polycrystalline diamond (PCD) layer on a WC-Co substrate, and having high hardness and abrasive resistance, are used in a variety of drilling and machining applications (Farhad, 2001; Sadi and Muzaffer, 2001). However, due to differences of thermal and mechanical properties in diamond and WC-Co substrate, residual thermal stresses develop in regions near the interfaces during fabrication. The diamond coating exhib… 相似文献
13.
随着我国旅游业的快速发展,旅游景区开发速度也在加快,旅游景区已成为旅游业的一个具有广阔发展前景的子行业。旅游景区的快速发展需要大批相应的专业技术人才,然而,与此不相适应的是目前我国旅游景区开发与管理专业人才培养落后于景区对相应人才的需求。作者利用文献资料、问卷调查和实地走访调查资料,分析了目前我国旅游景区对人才的需求情况。 相似文献
14.
本文建立了热残余应力分析的数学模型，采用数值方法对陶瓷涂层材料的热残余应力进行了分析，得出了金属基底的弹性性能、过渡层的厚度和陶瓷涂层的孔隙率对热残余应力的影响，为含FGM的陶瓷涂层材料的优化提供了一种理论分析方法。 相似文献
15.
Validity evidence for the Chinese version Classroom Appraisal of Resources and Demands (CARD) 
下载免费PDF全文
下载免费PDF全文 Juan Zhang Chuang Wang Richard Lambert Chenggang Wu Hongbo Wen 《Psychology in the schools》2017,54(9):1079-1093
The Classroom Appraisal of Resources and Demands (CARD) was designed to evaluate teacher stress based on subjective evaluations of classroom demands and resources. However, the CARD has been mostly utilized in western countries. The aim of the current study was to provide aspects of the validity of responses to a Chinese version of the CARD that considers Chinese teachers’ unique vocational conditions in the classroom. A sample of 580 Chinese elementary school teachers (510 female teachers and 70 male teachers) were asked to respond to the Chinese version of the CARD. Confirmatory factor analyses showed that the data fit the theoretical model very well (e.g., CFI: .982; NFI: .977; GFI: .968; SRMR: .028; RMSEA: .075; where CFI is comparative fit index, NFI is normed fit index, GFI is goodness of fit, SRMR is standardized root mean square residual, RMSEA is root mean square error of approximation), thus providing evidence of construct validity. Latent constructs of the Chinese version of the CARD were also found to be significantly associated with other measures that are related to teacher stress such as self‐efficacy, job satisfaction, personal habits to deal with stress, and intention to leave their current job. 相似文献
16.
旅行成本法是当前研究旅游景区的游憩价值的通用方法之一,该方法将景区的游憩价值分为游客的旅行费用支出、时间价值以及游客消费者剩余三个部分.文章是在老君山进行了实地调查后,采用费用支出法、时间价值法以及消费者剩余法对老君山九十九龙潭景区游憩价值进行了评估,并通过在景区进行问卷抽样调查,建立了旅游费用与旅游人次数间的供给需求函数,求出了游客消费者剩余.在获得游客存在重游景区的情况下,对评估结果进行修正,最终得出了丽江老君山九十九龙潭景区游憩的总价值,并根据丽江市的年旅游人数估计了老君山九十九龙潭景区在不同游览比例下的游憩价值. 相似文献
17.
1 Introduction X-ray emission from laser-produced plasma is notonly of considerable interest for inertial confinementfusion application,but is also of i mportance to a num-ber of other applications[1-3].Thelaser-plasma interac-tion can be efficient , bright , and versatile source ofX-rays . X-ray emission shows a remarkable variation withlaser wavelength . Shorter wavelengths are more effi-cient for producing quasi-thermal plasma emission.Longer wavelength laser-plasma interactions have pro-d… 相似文献
18.
Jackie Lanum Michael E. Campbell Dennis W. Blick Josephine Knox Thomas G. Wheeler 《Learning & behavior》1984,12(2):195-201
Many rat studies of learned helplessness confound the stress of restraint with inescapable shock. In the present experiment, albino rats were held immobile for 0, 2, 8, 14, or 18 h. Behavioral deficits were observed in an open-field activity maze and in two-way shuttlebox avoidance acquisition. In the activity maze, a sex X restraint interaction was observed for latency to leave the center square, ambulation, and frequency of center square crossing. Males were slower to leave the center square, had fewer ambulations, and crossed the center square less frequently than females. These effects were potentiated by restraint. Males reared significantly less than females, and restrained animals reared significantly less than nonrestrained animals. Restraint also significantly increased the frequency of grooming. On the avoidance tasks, a significant restraint X trial block interaction indicated slower learning for restrained animals. The severity of the decrements increased with restraint duration. The presence of stomach lesions was positively correlated with stress duration and the severity of the behavioral decrement. The results indicate that restraint produces a variety of behavioral changes which may result in interpretive difficulties for helplessness studies that confound restraint and shock. 相似文献
19.
As an important mooring arrangement in the na-val vessel, the lap link is used to join the tympanicring in lay day or for draught proofing,the capabilityof which is of vital importance to the safety of the ves-sel and personnel. However, existing lap link… 相似文献
20.
文章在实地调查稻城亚丁旅游景区自驾游发展现状的基础上,针对国家4A级旅游景区自驾游服务体系建设中存在的问题,分析了该景区信息互动、交通管理、游客救助及汽车俱乐部、旅行社、旅馆、景区等支撑要素,基于自驾车旅游过程中的行前、行中、景区内、行后反馈四个阶段,创新性地提出了稻城亚丁自驾车服务体系构建的新思路和新框架,以期为政府、旅游企业、自驾车游客提供借鉴和参考。 相似文献