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确定应力集中的三应变片测定法 总被引:3,自引:1,他引:3
本文提出用三片应变片测定应力集中处的最大应力,给出了相应的外推计算公式及修正式,精度较高,使用简便. 相似文献
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合成了二苯甲酰甲烷与N,N-二甲基丙二胺混配配合物Zn(dmapa)(dbm)2(1) 和Cd(dmapa)(dbm)2(2)。用元素分析、红外光谱对配合物进行了表征,并用X-射线单晶衍射测定了配合物的晶体结构。配合物1属单斜晶系,P21/n空间群;配合物2属三斜晶系,P1 空间群。中心金属离子(Zn、Cd)与来自2个dbm-配体的4个O原子和来自dmapa配体的2个N原子配位,形成变型的八面体构型。研究了2个配合物的热稳定性。 相似文献
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推求应力集中处最大应力的确切值 总被引:6,自引:0,他引:6
本文提出一种由应力集中处附近已知的三点应力或应变值推求最大应力值的方法.实例表明,精度较高,使用简便. 相似文献
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A new mononuclear Co(II) complex, [Co(hmz)2(H2O)4]·2H2O, has been synthesized by the reaction of Co(CH3COO)2·4H2O with 1-(4-hydroxyphenyl)-5-mercaptotetrazole (Hhmz). It crystallizes in the monoclinic system, space group P21/n with a = 13.502(5), b = 6.718(3), c = 13.972(6) , β = 117.532(4)o, V = 1123.9(8) 3, Z = 2, M r = 553.45, F(000) = 570, Dc = 1.635 g/cm3, μ = 1.008 mm–1, the final R = 0.0272 and wR = 0.0684 for 2194 observed reflections (I > 2σ(I)). The Co(II) is six-coordinated by two nitrogen atoms from two hmz–1 ligands and four water molecules, forming an octahedral geometry. The intermolecular hydrogen bonding and offset-panel π-π stacking interactions between the adjacent molecules extend the compound into a three- dimensional supramolecular framework. The title compound emits strong blue fluorescent light (λem(max) = 427 nm) at room temperature and is red-shifted compared with free ligand Hhmz (λem(max) = 342 nm). 相似文献
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The novel coordination polymer {[Cd(p-CMSP)(Him)(H2O)]·3H2O}n (
p-CMSP2-=p-(carboxymethoxy)phenylthioacetate, Him=imidazole) was synthesized by the reaction of
Cd(NO3)2, imidazole and p-(carboxymethoxy)phenylthioacetic acid in an aqueous solution, and characterized by elemental analysis, IR, TG and single crystal X-ray diffraction. The crystal structure is of monoclinic, space group
P21/c with a=1.144 0(2) nm, b=1.876 7(4) nm, c=0.877 89(18) nm, β=106.31(3)° and V=1.808 9(7)
nm3, Z=4, R=0.023 2, wR=0.051 4. Each Cd(II) atom displays a distorted octahedral coordination geometry, defined by three carboxyl O atoms from different
p-CMSP2- ligands, one S atom from thioether, one N atom from imidazole and one water molecule. Adjacent Cd(II) ions are bridged by
p-CMSP2- groups, resulting in a 2D layer structure. The adjacent Cd…Cd distances are 0.492 7 nm and 1.144 0 nm. Furthermore, such layers are linked through hydrogen bonds to form supramolecular network. CCDC: 269474. 相似文献
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为解决螺旋槽干气密封流场计算中一阶线性滑移边界条件下得到的泄漏量与实验结果之间存在较大误差的问题,在一阶线性滑移边界条件的基础上,推导出二阶非线性滑移边界条件下的修正的广义雷诺方程,应用迭代法、PH 线性化方法等求解非线性雷诺方程,获得了气膜压力、流速、泄漏量的近似解.利用Maple程序计算了工程实例中不同转速和不同压力情况下的泄漏量,并与一阶线性滑移边界条件下的泄漏量和实验数值进行比较.结果表明:在工程实例中,压力相同时,泄漏量随转速的增大而增大,一、二阶最大相对误差分别为14.4%、5.4%;转速相同时,泄漏量随压力的增大而增大,一、二阶最大相对误差分别为33.3%、13.3%.本文未考虑干气密封内部的振动情况,因此一、二阶理论计算值小于实际测试值.二阶非线性滑移边界条件下的泄漏量值比一阶线性滑移边界条件下的泄漏量值更加接近实验数值,特别是在工程实例中转速、压力较低的工况下更加明显. 相似文献