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在S-紧空间中讨论了几个S-分离空间之间的关系,给出了S_2-空间成为S_3*-空间,S_3*-空间成为S_4*-空间的一个充分条件。主要结论:设X是-S紧空间,且具有有限半开集可交性,则(1)若是S_2-空间,则X是S_3*-空间;(2)若是S_2-空间,则X是S_4*-空间;(3)若是S_3*-空间,则X是S_4*-空间。 相似文献
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TANG Guoyi ZHENG Yangzeng Yanshan University Qinhuangdao ChinaCAI Qigong ZHU Jing Central Iron Steel Research Institute Ministry of Metallurgical Industry Beijing China TANG Guoyi Dept.of Graduates Central Iron Steel Research Institute Ministry of Metallurgical Industry Beijing China 《金属学报(英文版)》1990,3(3):177-182
The effects of chemical composition and cooling rate after solidication on the grain coarseningtemperature,T_(GC),of the V-Ti-N microalloyed steels have been investigated.It is shownthat the T_(GC) may be obviously raised by adding even a little Ti to the base steel so as to pre-cipitate a great deal of fine Ti-bearing particles of about 10 nm.The T_(GC) does not increasewith the cooling rate,as it is over a certain critical value.The T_(GC) is insensitive to any varia-tion of N content at simulated cooling condition of 150 mm continuous cast slab.TheT_(GC) may be dropped down about 100℃ by adding 0.33 wt-%Mo to the steels.The sensitivi-ty of T_(GC) to cooling condition relates to the Ti and V contents. 相似文献
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The heterogeneous distribution of C and metallic alloying elements as well as the phase com- position changes before and after cold deformation of an Fe-Mn-Cr-C alloy have been stu- died by the use of Mssbauer spectroscopy.The austenites without and with C and metallic alloying elements are found in the alloy in as-solid solution state.While the martensites with- out and with C and alloying elements may be induced by cold deformation.The transforma- tion from austenite to martensite in the alloy is confirmed via theoretical computation and ex- periments to be controlled by the number of covalent electron pairs forming covalent bond in austenitic crystal cell of the alloy.The formation of strong covalent bond between C and me- tallic elements can vigorously retard the γ/α' transformation. 相似文献
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点阵图形LCD在机械故障诊断仪表中的应用 总被引:1,自引:0,他引:1
介绍了点阵式图形液晶显示模板MGLS240X128与MCS-51单片机的接口实现方法,人出了用单片机的C语言编制的液晶显示驱动的通用程序以及其在机械故障诊断技术中的应用实例。 相似文献
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采用Gleeble-3500热模拟实验机,对铌微合金钢Q345B进行热压缩实验.基于所获实验结果,充分考虑了热变形工艺参数(应变速率和变形温度)和动态软化机制(动态回复和动态再结晶)对流变应力的影响,建立了一种考虑动态软化机制影响的高温变形显式本构模型,给出了本构方程求解的方法,确定了模型中与工艺参数相关的主要参数的定量关系式;其主要特点是能够较准确地描述材料在高应力区域的动态回复软化阶段、动态再结晶软化阶段和稳定流变阶段的应力应变关系.模型验证表明,所建立模型预测出的流变曲线与实验结果吻合良好. 相似文献
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用内转换Mossbauer谱分析了Fe-Mn-Cr-C合金冷变形前后合金元素原子与碳原子的不均匀分布和相组成。发现该合金在固溶处理状态时为两类奥氏体,即无碳奥氏体和含碳奥氏体;经变形诱发出不含碳与合金元素的无碳马氏体(类α-Fe)及含碳与合金元素的合金马氏体。理论计算和试验证实:该合金中奥氏体向马氏体转变是受奥氏体晶胞内共价键中共用电子对的数目(n_A值)大小所控制。合金元素原子与碳原子之间形成结合力较强的C-M_e共价键,这对合金马氏体的形成具有强烈的阻碍作用。 相似文献