排序方式: 共有16条查询结果,搜索用时 15 毫秒
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运用球面成像原理,应用物像同屏和物像异屏方法,采用透镜折反折和折折成像,测定双凸厚透镜的曲率半径和折射率,并利用焦距公式计算得双凸厚透镜的焦距.该实验测定方法,体现了透镜成像的过程,得到了双凸厚透镜曲率半径和折射率的计算公式,拓展了透镜光学参量测定的方法和途径. 相似文献
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Theoretical analysis is made on the temperature field at the time of pulse current discharge in a metal structure with an elliptical embedding crack. In finding the temperature field, analogy between the current flow through an elliptical embedding crack and the fluid flow through a barrier is made based on the similarity principle. Boundary conditions derived from this theory are introduced so that the distribution of current density and the temperature field expressions can be obtained. The study provides a theoretic basis to the applications of stopping spatial crack with electromagnetic heating. 相似文献
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T10钢金属模具中裂纹电磁热止裂的实验研究 总被引:2,自引:1,他引:2
自主设计了改进型ZL-2超强脉冲电流发生装置,采用它对T10金属模具钢中裂纹进行脉冲放电止裂。放电时裂纹尖端熔化形成堆焊和高压应力区,使裂纹尖端钝化,达到了止裂的目的。由于脉冲放电超快速加热和冷却,在裂纹尖端处实现了冲击淬火,得到了超细化的隐晶马氏体和细粒碳化物等微观组织,同时围绕裂纹尖端形成了白亮层组织,提高了裂纹尖端处的硬度、强韧性和耐磨性,实验结果验证了理论研究和数值模拟的结果,为将电磁热裂纹止裂技术应用到金属模具裂纹止裂中,进行了基础实验工艺的研究工作。 相似文献
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将纳米金粒子负载于氧化铟锡导电玻璃(ITO)表面作为电化学发光(ECL)工作电极,建立了简单、快速测定二肽的方法.采用透射电镜、扫描电镜、电化学和光谱等技术方法表征材料和所制备电极的性能.在最优条件下,组氨酸-丙氨酸二肽分子(His-Ala)对鲁米诺在此电极上的ECL有显著的猝灭作用,从而可以对二肽进行检测.在2.44×10-11~1.22×10-7 mol/L浓度范围内,ECL响应和二肽浓度有良好的线性关系,检出限为2.42×10-12 mol/L(S/N=3).人体内胰高血糖素样肽-1(GLP-1)在二肽基肽酶IV(PDD-IV)作用下失去活性并释放出同量的His-Ala二肽,因此,本方法可通过测定血液中二肽浓度间接测定GLP-1,以及评估PDD-IV和其抑制剂的活性.上述DPP-IV抑制剂可调节2型糖尿病人血液GLP-1在正常水平,是糖尿病研究和治疗中具有潜在价值的药物设计靶点. 相似文献
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采用40 wt.%稀硫酸加压浸出湿磨活化钛铁矿富集二氧化钛,着重考察了磨球尺寸配比(Φ10mm+Φ20mm)、球料比、球磨时间以及浸出时间对钛铁矿富集的影响。结果表明,采用Φ10mm单一磨球活化时TiO2富集效果最好,提高球料比可以强化钛铁矿的浸出,延长球磨时间会增加铁和钛的浸出,但当球磨时间超过120min时,球磨时间对浸出的影响很小。获得了优化的湿磨活化条件:磨球尺寸Φ10mm、球料比20∶1和球磨时间2h。此条件下的湿磨钛铁矿在反应温度150℃、硫酸浓度40 wt.%和酸矿比2∶1下浸出反应3h,所得富钛料中TiO2含量达到~84%。本研究结果表明,将浅度浓缩至~40wt.%的硫酸法钛白废酸用于攀枝花钛铁矿的加压浸出制备富钛料是可行的。 相似文献
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THERMAL STRESS FIELD WHEN CRACK ARREST IN AN AXIAL SYMMETRY METAL DIE USING ELECTROMAGNETIC HEATING 总被引:1,自引:0,他引:1
In order to solve the thermal stress field around crack tip in metal die when crack prevention using electromagnetic heating, a metal die with a half-embedded round crack was selected as the study object. The complex function method was used as a basis for the theoretical model of the space crack prevention in metal dies using electromagnetic heating. The crack arrest was accomplished by a pulse current discharge through the inner and outer. The theoretical analysis results show that the temperature around the crack tip rises instantly above the melting point of the metal. Small welded joints are formed at a small sphere near the crack tip inside the metal die by metal melting as a result of the heat concentration effect when the current pulse discharged. The thermal compressive stress field appears around the crack tip at the moment. The research results show that the crack prevention using electromagnetic heating can decrease the stress concentration and forms a compressive stress area around the crack tip, and also prevents the main crack from propagating further, and the goal of crack preventing can be reached. 相似文献
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