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921.
以密度泛函理论为基础,使用投影缀加波方法、VASP程序包研究了FeMnP_(1-x)T_x(T=Si,Ga,Ge)化合物的力学性质,结果表明FeMnP_(1-x)Ga_x化合物的晶格参数、弹性常数和电子结构与FeMnP_(1-x)Ge_x化合物比较接近,同时该化合物在力学上稳定,是预期具有较大的磁熵变和高磁热效应的材料.依据Pugh判据,FeMnP_(0.67)T_(0.33)(T=Si,Ga,Ge)化合物具有良好的延展性,三者之中FeMnP_(0.67)Ga_(0.33)韧性最好,FeMnP_(0.67)Si_(0.33)韧性相对较差,说明Ga替代P可改善此类化合物的机械性能.最后从化合物体系电子总态密度随不同掺杂T原子的演化规律解释了自洽计算得到的弹性常数的变化规律. 相似文献
922.
923.
Ning Guan Tao Luan Guilin Jiang Zhi-Gang Liu Cheng-Wu Zhang 《Heat and Mass Transfer》2016,52(2):393-405
Experimental investigations were carried out to explore the convective heat transfer in micro pin-fins with different aspect ratios, and the influence of heating load on Nusselt numbers in micro pin-fins with liquid water as working fluid were investigated. The mechanism of convective heat transfer in micro pin-fins at different heating load were studied by 3-D numerical investigations, and the relationships of thermal physical properties change, the end wall effect and axial thermal conduction with Nu numbers in micro pin-fins were analysed. It was found that the thickness of boundary layer was decreased as much as 33.3 % attributed to the destructive effect of thermal physical properties change, and convective heat transfer in the micro pin-fin channel was more than 20 % enhanced by the flow disturbance caused by the increase of temperature difference. The discrepancy of Nu in micro pin-fin channel with different aspect ratios reached 34.59 %, and this discrepancy was reduced by the increase of heating load. The maximum value of impact factors of dynamic viscosity and thermal conductivity on the Nu in micro-pin-fins reached 25.02 and 7.68 %, respectively. 相似文献
924.
Guan Huang 《Journal of Dynamics and Differential Equations》2016,28(2):375-387
Consider a weakly nonlinear CGL equation on the torus \(\mathbb {T}^d\): Here \(u=u(t,x)\), \(x\in \mathbb {T}^d\), \(0<\epsilon <<1\), \(\mu \geqslant 0\), \(b,c\in \mathbb {R}\) and \(m,p,q\in \mathbb {N}\). Define \(I(u)=(I_{\mathbf {k}},\mathbf {k}\in \mathbb {Z}^d)\), where \(I_{\mathbf {k}}=v_{\mathbf {k}}\bar{v}_{\mathbf {k}}/2\) and \(v_{\mathbf {k}}\), \(\mathbf {k}\in \mathbb {Z}^d\), are the Fourier coefficients of the function \(u\) we give. Assume that the equation \((*)\) is well posed on time intervals of order \(\epsilon ^{-1}\) and its solutions have there a-priori bounds, independent of the small parameter. Let \(u(t,x)\) solve the equation \((*)\). If \(\epsilon \) is small enough, then for \(t\lesssim {\epsilon ^{-1}}\), the quantity \(I(u(t,x))\) can be well described by solutions of an effective equation: where the term \(F(u)\) can be constructed through a kind of resonant averaging of the nonlinearity \(b|u|^{2p}+ ic|u|^{2q}u\).
相似文献
$$\begin{aligned} u_t+i\Delta u=\epsilon [\mu (-1)^{m-1}\Delta ^{m} u+b|u|^{2p}u+ ic|u|^{2q}u]. \end{aligned}$$
(*)
$$\begin{aligned} u_t=\epsilon [\mu (-1)^{m-1}\Delta ^m u+ F(u)], \end{aligned}$$
925.
Pei-Xian Li Meng-Yun Guan Chang-Gen Yang Peng Zhang Jin-Chang Liu Yong-Peng Zhang Cong Guo Yi Wang 《中国物理C(英文版)》2016,40(11):116005-116005
Liquid argon (LAr) is an attractive target for the direct detection of WIMPs. A LAr prototype detector was designed to study the technology and properties of LAr detectors. The prototype detector had an active volume containing 0.65 kg of liquid argon. A liquid nitrogen (LN) cooling system allowed the temperature fluctuation of the liquid argon to be controlled within less than 0.1 K during a one month run. In the 22Na calibration run, the LAr prototype obtained 1.59±0.02 p.e./keV light yield for 511 keV gamma rays using a domestic-made argon purification system. 相似文献
926.
本文以典型轴类零件为例,详细阐述利用数控加工模拟仿真软件加工零件的操作方法和步骤,对数控加工仿真软件在数控实践教学中的应用效果进行了深入的讨论,同时指出教学过程中使用仿真软件的不足,并给出了合理建议。 相似文献
927.
928.
考虑基于计算机视觉技术的未受精种蛋无损检测中特征参数之间关系的复杂性和模糊性等因素,提出了一种基于改进投影寻踪模型和模糊神经网络相结合,作为种蛋是否受精品质归属的决策系统.利用量子投影寻踪技术对种蛋图像的复杂形状特征向量进行提取降维,给出了计算最佳投影方向的一种改进量子遗传算法;并且利用模糊神经网络的自动学习决策推理规则,实现了种蛋是否受精品质归属的无损检测.结果表明:该模型速度快且稳定,精度高且鲁棒性好,简单易于实现,精度达到99.37%,满足实际检测要求. 相似文献
929.
Ti-Cu-Zr-Fe-Nb ultrafine structure-dendrite composites were designed by inducing Nb and more Ti to a Ti-Cu-Zr-Fe glass-forming alloy composition and prepared by copper mold casting.The composite alloys consist of β-Ti dendrites and ultrafine-structured CuTi2 and CuTi phases as well as a trace amount of glassy phase.The volume fraction of β-Ti dendrites increases with the increase in content of Nb which acted as the β-Ti phase stabilizer in the alloys.The composites exhibit high compressive yield strength exceeding1200 MPa,maximum strength around 1800 MPa and low Young’s modulus around 48 GPa.The plasticity of the alloys is strongly influenced by the volume fraction and morphology of the dendritic β-Ti phase,and the compressive plastic strain was enlarged from 5.9%for the 4 at%Nb alloy to 9.2%for the 8 at%Nb alloy.The preliminary cell culture experiment indicated good biocompatibility of the composite alloys free from highly toxic elements Ni and Be.These Ti-based composite alloys are promising to have potential structural and biomedical applications due to the combination of good mechanical properties and biocompatibility. 相似文献
930.
Isolation and characterization of H7N9 viruses from live poultry markets--Implication of the source of current H7N9 infection in humans 总被引:1,自引:0,他引:1
SHI JianZhong DENG GuoHua LIU PeiHong ZHOU JinPing GUAN LiZheng LI WenHui LI XuYong GUO Jing WANG GuoJun FAN Jun WANG JinLiang LI YuanYuan JIANG YongPing LIU LiLing TIAN GuoBin LI ChengJun CHEN HuaLan 《科学通报(英文版)》2013,58(16):1857-1863
On March 31, 2013, the National Health and Family Planning Commission announced that human infections with a previously undescribed influenza A (H7N9) virus had occurred in Shanghai and Anhui Province, China. To investigate the possible origins of the H7N9 viruses causing these human infections, we collected 970 samples, including drinking water, soil, and cloacal and tracheal swabs of poultry from live poultry markets and poultry farms in Shanghai and Anhui Province. Twenty samples were positive for the H7N9 influenza virus. Notably, all 20 viruses were isolated from samples collected from live poultry markets in Shanghai. Phylogenetic analyses showed that the six internal genes of these novel human H7N9 viruses were derived from avian H9N2 viruses, but the ancestor of their HA and NA genes is uncertain. When we examined the phylogenetic relationship between the H7N9 isolates from live poultry markets and the viruses that caused the human infections, we found that they shared high homology across all eight gene segments. We thus identified the direct avian origin of the H7N9 influenza viruses that caused the human infections. Importantly, we observed that the H7N9 viruses isolated from humans had acquired critical mutations that made them more "human-like". It is therefore imperative to take strong measures to control the spread of H7N9 viruses in birds and humans to prevent further threats to human health. 相似文献