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1.
在T=110~195℃及ε=0.4×10(-3)~2.47×10(-3)S(-1)时对Zn-1.8%Al合金超塑性m-δ曲线进行了测定,属mL=mmin型。可分为基本形式、上升式及下降式三种形式。应用CL(刘勤)方程式对C值进行了计算,获得了全部有关特征参数,包括(δ0=0),δL,δF;m0(≠0),mL,mF;(C0=k0/k0=1),CL(=kL/k0)及CF(=kF/k0)的全部或一部分,由曲线的形式决定。测到的总延伸率δF=190/~410%.各自由每根m-δ曲线的其余特征参数的动静态或直间接效应的综合结果所决定。进一步否定了当前超塑性领域内存在的错误观点。并对有关微观变化进行了初步研究。 相似文献
2.
建立了准确、超灵敏的多种单端孢霉烯族毒素的分析方法。方法采用负离子化学电离GC-MS技术对十六种单端孢霉烯族毒素的七氟丁酰化衍生物进行气相色谱分离和质谱电离。对每种单端孢霉烯族毒素选择4-5特征碎片离子进行检测,并根据其碎片离子的相对强度和气相色谱保留时间进行鉴定,其检测限可达5×10(-11)~0.4×10(-12)g。以单离子进行检测,检测限可达1×10(-11)~6×10(-15)g。该法应用于粮食样品及培养物的测定,检出了以前所建各种方法未曾检出的多种单端抱霉烯族毒素。 相似文献
3.
本工作利用一台不作任何较大改动的CAMECA-IMS-3f扇形磁铁型二次离子质谱仪对传统的离子散射谱(ISS)分析技术进行了适当的变通,并对二次离子质谱分析(SIMS)的深度剖析谱进行了浓度定标。在保留SIMS分析高灵敏度、高深度分辨率的前提下,实现了对块体样品中的掺杂元素的SIMS定量深度剖析。通过与离子注入机标称的注入剂量及卢瑟福背散射的定量分析结果相比较,本方法的定量准确度一般好于10%。而精确度则好于5%。本文对该方法的背景、基本原理、实验方法,准确度及优缺点等进行了较详细的讨论。 相似文献
4.
本文介绍了一种应用气体扩散池的光学流动液射分析(FIA),测定酒中亚硫酸盐的方法。该方法的机理如下:从基体中释放出来的SO2穿过渗透膜扩散到指示溶液中,引起pH值的变化,而使指示溶液的吸光度产生变化。使用指示剂是溴甲酚绿。该方法可测定1-20mg/l范围的SO3^2-,最低检测限为0.1mg/l。对酒分析的重现性为0.7-1.5%。对由所有溶液添加10%(V/V)乙醇、用N2气彻底吹洗,是获得可靠 相似文献
5.
同位素稀释质谱法测定酸雨标准物质中微量钾和镁 总被引:2,自引:1,他引:2
本文叙述了同位素稀释质谱法(IDMS)测量微量钾和镁的方法,并用该法对酸雨标准物质中含量在10-8~10-7量级的钾和镁进行了测定,同时对如何减小污染、降低空白、提高测量精度等问题进行了研究。 相似文献
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本文介绍一种在稍微酸性的溶液(0.00015-0.016mol^-1H2SO4)中,用5.7-二溴-8-羟基喹啉(DBHQ)作新型分光光度试剂,快速测定钒(V)的超灵敏和高选择的非萃取分光光度法。反应是瞬时的,吸光度保持稳定超过48h。发现平均摩尔吸收系数和Sandell灵敏度分别为6.1×10^3l mol^-1cm^-1和0.015μg cm^-2V(V)。获得了0.1-20μg ml^-1( 相似文献
8.
ТОмаЛ-10双层刀片的使用效果10双层刀片是以硬质合金作基体、-10超硬材料作工作层(厚度0.3~1.5mm)的一种双层烧结刀片,其硬度比硬质合金刀片高1~3倍,抗压强度为2~4GPa,耐热性达1100~1300℃。10刀片的组织均匀,对铁碳化合... 相似文献
9.
本工作利用一台不作任何较大改动的CAMECA-IMS-3f扇形磁铁型二次离子质谱仪对传统的离子散射谱(ISS)分析技术进行了适当的变通,并对二次离子质谱分析(SIMS)的深度剖析谱进行了浓度定标。在保留SIMS分析高灵敏度、高深度分辨率的前提下,实现了对块体样品中的掺杂元素的SIMS定量深度剖析。通过与离子注入机标称的注入剂量及卢瑟福背散射的定量分析结果相比较,本方法的定量准确度一般好于10%。而 相似文献
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Clarence W.DE SILVA 《Instrumentation》2019,(4):72-84
An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t... 相似文献
12.
INTEGRAL EQUATION METHOD'S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES 总被引:1,自引:0,他引:1
LI Cheng ZHENG Yanping 《机械工程学报(英文版)》2008,21(6):115-118
The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value. 相似文献
13.
30 keV Ga+ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z2, and shows a non-monotonic relationship between contrast and Z2. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z2, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory. 相似文献
14.
This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an... 相似文献
15.
分布动态载荷识别的抗噪处理 总被引:2,自引:2,他引:0
针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性. 相似文献
16.
The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar... 相似文献
17.
The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods.... 相似文献
18.
针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。 相似文献
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J. A. Williams 《Lubrication Science》1997,3(3):267-306
Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface. 相似文献
20.
CHEN Sunyi 《机械工程学报(英文版)》2007,20(6):13-17
A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion. 相似文献