Analysis of junction temperatures in high-power GaN-based LEDs

We presented the analysis of the incomplete conduction in bonding medium in high power GaN-based light-emitting diode (LED) packages. A numerical study was carried out with parametric model to understand the junction temperature variation due to bonding medium defects. Transient thermal measurement was performed to evaluate LED’s junction temperature. Thermal resistance from chip to lead frame was 20 K/W in our sample LED. It was suggested that only 60% of the surface area of the bonding medium was involved...     

化学铣切槽液中Na2S的分析

本文采用“碘量法”测定化铣液中的硫化钠，分析结果的准确度和精密度完全能够满足生产要求。     

Research on Action Strategies and Simulations of DRL and MCTS-based Intelligent Round Game

International Journal of Control, Automation and Systems - The reinforcement learning problem of complex action control in multiplayer online battlefield games has brought considerable interest in...     

Fast method for SAR echo simulation of a three-dimensional ground scene

Due to huge calculation of SAR echo simulation of a three-dimensional (3D) ground scene, a fast simulation method is proposed. First, the data of a 3D ground scene are fractionally interpolated based on the Fractional Brownian Motion (FBM) model. Second, the data interpolated are divided into lots of small facets whose precision meets the simulation requirement, the backscattering coefficients of the small facets are calculated. Third, the shaded area is judged by the comparison method of overlook angles. Three parallel levels are analyzed and the kernel function is designed. Finally, the computing method of reduction adding and external thread are also utilized under the framework of GPU in order to get high efficiency. With the methods mentioned above, the imaging result of experimental DEM data verifies the validity and superiority of the proposed method.     

频率响应法研究噻吩在CeY分子筛上的吸附行为

以NaY、液相Ce离子交换改性的Y型分子筛(L-CeY)为研究对象,运用N2吸附、XRD、NH3-TPD和Py-FTIR等实验方法表征两种Y型分子筛的物化性能。采用频率响应技术(FR)和智能重量分析仪(IGA)研究噻吩在两种分子筛上的吸附行为,并考察噻吩在稀土离子改性Y型分子筛上的不同吸附作用模式。结果表明,频率响应技术能够有效识别分子筛孔道内发生的不同传质过程。噻吩在NaY分子筛上的吸附行为较为简单,存在孔道吸附和π电子相互作用两种吸附过程;而在L-CeY分子筛上吸附行为较为复杂,同时存在孔道吸附和"S-M"吸附等多种吸附过程,另外,在高温条件下,还存在复杂的催化反应过程。     

Degradability and biocompatibility of bioglass/poly(amino acid) composites with different surface bioactivity as bone repair materials

Bioglass (BG) possesses excellent bioactivity and has been widely used in the manufacture of biomaterials. In this study, a composite with different surface bioactivity was fabricated via in situ melting polymerization by incorporating BG and poly(amino acid) (PAA) at a suitable ratio. The structure of the composite was characterized by Fourier transform infrared spectroscopy and XRD. The compressive strength of the BG/PAA composites was 139 MPa (BG:PAA = 30:70). The BG/PAA composites were degradable, and higher BG in composite showed higher weight loss after 4 weeks of incubation in simulated body fluid. In addition, the BG/PAA composite maintained adequate residual compressive strength during the degradation period. The SEM results showed the differences in surface bioactivities of the composites directly, and 30BG/PAA composite showed thicker apatite layer and higher Ca/p than 15BG/PAA. in vitro MG-63 cell culture experiments showed that the composite was noncytotoxic and thus allows cells to adhere, proliferate, and differentiate. This indicates that the composite has good biocompatibility. The implantations in the bone defects of rabbits for 4 and 12 weeks were studied. The composites had good biocompatibility and were capable of guiding new bone formation without causing any inflammation. The composite may be successfully used in the development of bone implants.     

Size and pressure effects on solid transition temperatures of ZrO2

Transition temperatures between tetragonal and monoclinic polymorphs of ZrO₂ nanoparticles, thin films and nanostructured materials are calculated by considering energetic contributions of surface (interface) energy and surface stress on total Gibbs free energy. The transition temperatures drop as the size of the nanocrystals decreases, which is consistent with available results.     

FORMATION OF μ-PHASE AND ITS EFFECT ON MECHANICAL PROPERTIES OF CAST NICKEL-BASE SUPERALLOYS

本文研究了铸造镍基高温合金中沉淀的片状μ相,揭示了μ相的形成规律、化学成份、TTT曲线、断裂特征和对力学性能的影响。研究结果表明,μ相的形成温度范围很宽,从800—1140℃。片状μ相的宽面是六方指数的{0001},它沿基体γ的{111}面板出。在760℃以下冲击,拉伸和持久的断裂特征是沿μ相{0001},面解理断裂,电子空位数N_v值不是控制μ相形成的唯一因素,还与(Mo+W)at.-％和Mo(Mo+W)有关。此外,硼也是抑制μ相的有效因素。     

用计算机图形处理软件定量分析SEM图像

用图形处理软件PHOTOSHOP对SEM图像进行图像定量分析，对高温合金K23σ析出相的体积分数和M8钢样的夹杂物颗粒尺寸进行了定量测定。结果表明，该方法操作方便，有一定的可行性。     

铝—钢双金属复合轧制层厚比及轧制力的研究

用实验方法研究了铝－钢双金属复合轧制时层厚比的变化规律。给出了双金属复合时轧制力的计算式。