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研究磁电弹性体中螺型位错与唇口裂纹的相互作用。结合Muskhelishvili方法和干扰技术, 在假定裂纹面具有不可渗透条件下得到磁电弹性体中由位错和唇口裂纹所诱导的应力场、电场和磁场的解析解。应用广义Peach-Koehler公式,得到作用在位错上的影像力。通过数值算例,得到场强度因子的变化规律及影像力和广义力随位错位置的变化规律。  相似文献   
2.
Metal organic chemical vapor deposition(MOCVD) growth systems are one of the main types of equipment used for growing single crystal materials, such as GaN. To obtain film epitaxial materials with uniform performance,the flow field and temperature field in a GaN-MOCVD reactor are investigated by modeling and simulating. To make the simulation results more consistent with the actual situation, the gases in the reactor are considered to be compressible, making it possible to investigate the distributions of gas density and pressure in the reactor.The computational fluid dynamics method is used to study the effects of inlet gas flow velocity, pressure in the reactor, rotational speed of graphite susceptor, and gases used in the growth, which has great guiding significance for the growth of GaN film materials.  相似文献   
3.
姜丽娟  张兆国 《有机化学》2006,26(5):618-626
总结了近年来用于不对称催化羟醛缩合反应的各种有机小分子催化剂, 简要阐述了每种类型的催化剂的催化机理以及它们的优缺点, 同时对有机小分子催化反应的发展进行了展望.  相似文献   
4.
对由三个反射面构成的复合式法珀腔的光纤法珀压力传感器进行了输出光谱理论分析,提取了含有传感器腔长信息的包络.提出了基于干涉级次拟合的解调算法,仿真分析了传感法珀腔腔长范围为160~215μm的光谱信号.结果显示,在不同信噪比下,基于干涉级次拟合的算法可获得较好的测量准确度,同一信噪比下,该准确度不依赖腔长变化,也不依赖光谱解调波长分辨率变化.实验结果表明,基于干涉级次拟合结果曲线残差的均方根差为0.012μm,验证了该算法的有效性.  相似文献   
5.
The structural and magnetic properties of Sm ion-implanted GaN with different Sm concentrations are investigated. XRD results do not show any peaks associated with second phase formation. Magnetic investigations performed by superconducting quantum interference device reveal ferromagnetic behavior with an ordering tem- perature above room temperature in all the implanted samples, while the effective magnetic moment per Sin obtained from saturation magnetization gives a much higher value than the atomic moment of Sm. These results could be explained by the phenomenological model proposed by Dhar et al. [Phys. Rev. Lett. 94(2005)037205, Phys. Rev. B 72(2005)245203] in terms of a long-range spin polarization of the GaN matrix by the Sm atoms.  相似文献   
6.
对由三个反射面构成的复合式法珀腔的光纤法珀压力传感器进行了输出光谱理论分析,提取了含有传感器腔长信息的包络.提出了基于干涉级次拟合的解调算法,仿真分析了传感法珀腔腔长范围为160~215 μm的光谱信号.结果显示,在不同信噪比下,基于干涉级次拟合的算法可获得较好的测量准确度,同一信噪比下,该准确度不依赖腔长变化,也不依赖光谱解调波长分辨率变化.实验结果表明,基于干涉级次拟合结果曲线残差的均方根差为0.012 μm,验证了该算法的有效性.  相似文献   
7.
Jian-Kai Xu 《中国物理 B》2021,30(11):118101-118101
The effect of nitrogen flow and growth temperature on extension of GaN on Si substrate has been studied. By increasing the nitrogen flow whose outlet is located in the center of the MOCVD (metal-organic chemical vapor deposition) gas/particle screening flange and by increasing the growth temperature of HT-AlN and AlGaN buffer layers near the primary flat of the wafer, the GaN layer has extended more adequately on Si substrate. In the meantime, the surface morphology has been greatly improved. Both the AlN and GaN crystal quality uniformity has been improved. X-ray diffraction results showed that the GaN (0002) XRD FWHMs (full width at half maximum) decreased from 579 arcsec~ 1655 arcsec to around 420 arcsec.  相似文献   
8.
Pt Schottky diode gas sensors for CO are fabricated using A1GaN/GaN high electron mobility transistor(HEMTs)structure. The diodes show a remarkable sensor signal (3 mA, in N2, 2mA in air ambient) biased 2 V after 1% CO is introduced at 50℃. The Schottky barrier heights decrease for 36meV and 27meV in the two cases respectively. The devices exhibit a slow recovery characteristic in air ambient but almost none in the background of pure N2, which reveals that oxygen molecules could accelerate the desorption of CO and offer restrictions to CO detection.  相似文献   
9.
以猪、兔、羊、鸡的肝脏为材料,利用高频电感耦合等离子体原子发射光谱仪(ICP-AES)测定了其微量元素Zn、Fe、Cu、Mn的含量,新极谱仪测定了Se的含量,气相色谱仪测定了必需脂肪酸亚油酸(C反18:2)和γ-亚麻酸(Cγ-18:3)的含量。结果表明,Fe在所测五种微量元素中含量最高,Zn其次,Se最低。四种动物肝脏中,兔肝的Zn、Fe、Se含量(鲜重)最高.分别为34.00μg/g,151.70μg/g和0.14μg/g;羊肝的Cu含量(鲜重)最高,为65.72μg/g;鸡肝的Mn含量(鲜重)最高,为1.94μg/g。此外,在所测定的两种必需脂肪酸中,兔肝的亚油酸含量(鲜重)最高,为24.08%;鸡肝中γ-亚麻酸含量最高,为1.08%。结果提示,在选用动物肝脏作为营养素源和制备保健品时,应考虑微量元素和必需脂肪酸的含量特点,有效利用其营养价值。  相似文献   
10.
Lateral Schottky barrier diodes (SBDs) on A1GaN/GaN heterojunctions are fabricated and studied. The characteristics of the fabricated SBDs with different Schottky contact diameters and different Schottky-Ohmic contact spacings are investigated. The breakdown voltage can be increased by either increasing the Schottky-Ohmie con- tact spacing or increasing the Schottky contact diameter. However, the specific on-resistance is increased at the same time. A high breakdown voltage of 1400 V and low reverse leakage current below 20nA are achieved by the device with a Schottky contact diameter of 100 μm and a contact spacing of 40 μm, yielding a high V^2BR/ RoN,sp value of 194 MW.cm^-2.  相似文献   
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