基于三维胞元空间的MA双向并行路由算法

针对传统移动代理(MA)在监测无线传感器网络(WSNs)的感兴趣信息时产生的延迟较大和能耗较多问题,提出了基于三维胞元空间的MA双向并行(3D-BPMA)路由算法.3D-BPMA将MA与传统的客户/服务器(c/S)模式相结合,在胞元内利用C/S模式搜集信息,在单层胞元系统和路由器与路由器之间采用MA双向并行的策略进行传输.仿真结果表明:3D-BPMA与LCF,DSG-MIP算法相比减少了平均响应时间和网络平均能耗,提高了MA发送率.     

WAVE INTERACTION WITH PERFORATED CAISSON BREAKWATERS

The reflection coefficient of perforated caissons and the total horizontal forces acting on them were experimentally and numerically analyzed and discussed when wave propagates normally. To consider the viscosity effect of fluid and nonlinear action of waves on structures, the VOF (Volume Of Fluid) method combined with the k-ε turbulence model was used to simulate the interaction between waves and structures. Governing equations were solved with the finite difference method. Through 2D experimental study in the wave flume, the empirical relationship between the reflection coefficient of perforated caissons and the main affecting factors were obtained from the experimental data using the least square method. Also the correlation between the ratio of the total horizontal force acting on perforated caisson and the force acting on solid caisson and the main affecting factors were regressed from the experimental data.     

激光熔覆Ni基SiC合金涂层组织与性能的研究

利用5kWCO2连续波激光器在16Mn钢基材表面对含20%(体积比)SiC陶瓷粉末的镍基自熔性合金粉末进行激光熔覆得到Ni基SiC合金涂层(NiSiC)。研究了合金涂层的组织形貌及相结构,并用单纯的镍基合金涂层(Ni60)进行了显微硬度及滑动磨损性能的对比试验。结果表明,NiSiC合金涂层由γ枝晶及其间的共晶组织组成,主要组成相为γ-Ni,γ-(Ni,Fe)固溶体和(Cr,Fe)7C3,Cr23C6及(Cr,Si)3Ni3Si等化合物。添加SiC的镍基合金涂层NiSiC比单纯的镍基合金涂层Ni60具有较高的硬度和耐磨性。     

YAG激光熔覆的研究现状与发展趋势

本文介绍了YAG激光熔覆的特点，并与CO2激光进行了比较，显示了YAG激光熔覆的优势和潜力。叙述了YAG激光熔覆的研究进展及其应用前景。     

铸造镍基K3合金的激光熔覆开裂及工艺研究

研究了铸造镍基Ｋ３合金的激光熔覆过程，分析了原始组织及激光熔覆工艺参数对熔覆裂纹形成的及作用；探讨了使用激光熔覆技术对损伤的Ｋ３合金叶片进行修复的可能性。研究结果表明，Ｋ３合金中沿界分布的低熔点共晶及碳化物是引起激光熔覆开裂的主要因素，采用较高的功率密度和较快的扫描速度进行激光熔覆，可减少热影响区范围，明显地抑制熔覆裂纹的产生。     

Precipitation behavior of σ phase in fusion zone of dissimilar stainless steel welds during multi-pass GTAW process

The purpose of this study is to investigate the precipitation characteristics of σ phase in the fusion zone of stainless steel welds at various welding passes during a tungsten are welding (GTAW) process. The morphology, quantity, and chemical composition of the δ-ferrite and σ phase were analyzed using optical microscopy (OM), a ferritscope (FS), a X-ray diffractometer (XRD), scanning electron microscopy (SEM), an electron probe micro-analyzer (EPMA), and a wavelength dispersive spectrometer (WDS), respectively. Massive δ-ferrite was observed in the fusion zone of the first pass welds during welding of dissimilar stainless steels. The σ phase precipitated at the inner δ-ferrite particles and decreased δ-ferrite content during the third pass welding. The σ and δ phases can be stabilized by Si element, which promoted the phase transformation of σ→ϱ+λ₂ in the fusion zone of the third pass welds. It was found that the σ phase was a Fe−Cr−Si intermetallic compound found in the fusion zone of the third pass welds during multi-pass welding.     

LASER CLADDED TiCN COATINGS ON THE SURFACE OF TTTANIUM

Laser cladded coatings of TiCN were produced on the surface of titanium. To obtain the optimal techniques, several conditions were tested by varying the laser scanning rate. The choice of shielding gas was also studied. The cladded coatings were then evaluated from the surface mechanics point of view based on their microhardness. The microstructure of some interesting samples was investigated by optical micrographs （OM）. The results showed that under the condition of fixed pulse frequency and pulse width, the laser scanning rate and the shielding gas are the main factors influencing the components of coatings. TiCN coatings were decompounded and oxidized during the cladding process in the condition of no shielding gas of N2. X-ray diffraction results indicated that the composite coatings composed of TiCN, TiC, Ti2N, and TiO2 were produced using appropriate techniques. The results indicated that the best condition in terms of the surface microhardness is obtained when the scanning rate is 1.5mm/s, the pulse frequency is 15Hz, the pulse width is 3.0ms, and N2 is chosen as the shielding gas. The microhardness of the composite coatings is about 1331kg · mm^-2, which is about 4 times that of the substrate. The optical micrographs indicated that the cladding zone is made up of TiCN, TiO2 and some interdendritic Ti, but the diffusion zone mainly consists of the dendrites phase, and the cladded depth is about 80μm, which is more than 2 times that of the laser nitrided sample. There were no microcracks or air bubbles in the cladded sample, which was cladded using the above optimal techniques.     

激光熔覆用钴基合金粉末的研究

对激光熔覆用WFLC－11钴基合金粉末的激光熔覆工艺和熔覆层性能进行了研究，获得了WFLC－11钴基合金粉末激光熔覆层厚度与最小比能量关系曲线和熔覆层的组织、高温硬度等性能数据，为选择和使用WFLC－11钴基合金粉末提供了依据。     

Formation of WC/Ni hard alloy coating by laser cladding of W/C/Ni pure element powder blend

WC/Ni coating was formed by laser cladding of a W/C/Ni powder blend. The formed WC crystals have rectangular or quadrangle cross-section shapes with size of 2–30 μm. Step, twist and cross growth morphologies of WC formation were observed. The coating contains WC, CW_3, WNi, FeW₃C, Fe₆W₆C, W₃O, W, C, and (Fe,Ni) phases.     

锆基激光熔覆涂层组织结构及性能

在纯钛(TA2)基体上激光熔覆了Zr65Al75Ni10Cu17.5合金粉末，对涂层进行了XRD，SEM和TEM分析。研究发现，涂层由金属间化合物 少量的非晶组成。这种具有高比强度、高硬度和高抗氧化性的金属间化合物与非晶相的复合组织，具有较好的力学性能。在Zr65Al75Ni10Cu17.5合金粉末中添加w(B)2％和w(Si)2．75％，发现涂层中非晶含量增加，硬度升高。两种涂层的最高硬度分别达到HK909．6和HK1444．8。