一种带有可控动态参数的优化覆盖算法

能耗与覆盖问题是无线传感器网络研究领域的基本问题,也是一个重点问题。针对传感器节点所呈现的同构性特点,提出了一种带有可控动态参数的优化覆盖算法（OCCDP）。该算法首先给出了3节点联合覆盖时,最大无缝覆盖率的求解过程;其次,给出了在监测区域内存在传感器节点覆盖时,覆盖质量期望值求解方法以及与邻居节点进行覆盖比对时覆盖率的判定方法;当存在冗余覆盖时,给出了任意传感器节点处于冗余节点覆盖时的覆盖率的计算过程;最后,通过仿真实验与其他算法在覆盖质量和网络生存周期等方面进行对比,其性能指标平均提升了11.02%和13.27%,从而验证了提出算法的有效性和可行性。     

低耦合损耗的光电混合光纤旋转连接器

设计了一种光电混合光纤旋转连接器,能实现相对旋转的光信号在较大对准误差范围内低损耗连接.旋转状态下的自聚焦透镜准直光纤输出的光信号,并由PIN光电探测器将其转换为电信号,冉由激光器根据电信号再生出原始光信号继续在光纤通讯系统中传输.该光电混合光纤旋转连接器在离轴偏移量至520μm或对准倾斜角至0.5°时的附加耦合损耗为0.3 dB,而采用双自聚焦透镜的光纤旋转连接器要获得小于3 dB的插入损耗,其离轴偏移或倾斜角度必须小于100 μm和0.10°相比之下,本文设计的光纤旋转连接器能降低系统对机械加上及装配精度的要求,具有较高的实用价值.     

数字城市中建筑物模型与地形的拼接算法研究

约束边的嵌入是实现数字城市建筑物和地形拼接的算法基础,总结了约束边嵌入算法的特点和优缺点,提出改进的多边形嵌入算法,即一次性将多边形嵌入三角网中,在进行基础重构的基础上,进行优化处理.该算法能够适应多种情况,易于理解和实现,能够很好地符合工程要求.     

西藏查龙水电站混凝土面板施工

查龙水电站钢筋混凝土面板堆石坝由钢筋混凝土面板、趾板、防浪墙及各分缝止水系统及防渗帷幕等组成。本文系统地介绍了应用该部自行设计的无轨式滑模进行面板施工的经验，以及混凝土原材料、配合比、浇筑、保温、混凝土质量控制和面板坝的分缝止水系统等施工情况。实践证明，在高寒缺氧地区采用这一施工措施，混凝土面板施工质量优良。     

高匹配焊接接头裂纹的J积分研究

本文研究了含有纵向裂纹或缺陷的高匹配焊接接头材料不均匀性和焊缝宽度对弹塑性断裂表征参量J积分的影响规律.高匹配焊缝被理想化为含有一平行裂纹的一个硬夹层,其屈服应力高于母材.在平面应力条件下利用弹塑性有限元计算得到数值解.研究结果表明,材料不均匀性和焊缝宽度对J积分值有显著影响,特别当名义应力或名义应变较高时影响更大.因此,估算高匹配接头的裂纹推力时必须对此加以考虑.     

滑球型同步万向联轴器运动分析

球笼同步万向联轴器有几种结构形式,滑球型同步万向联轴器是其中的一种,本文主要介绍这种形式的联轴器的运动原理。     

Microstructural modifications and properties of Sn-Ag-Cu solder joints induced by alloying

Slow cooling (1–3°C/sec) of Sn-Ag-Cu and Sn-Ag-Cu-X (X = Fe, Co) solder-joint specimens, made by hand soldering, simulated reflow in a surface-mount assembly to achieve similar as-solidified joint microstructures for realistic shear-strength testing, using Sn-3.5Ag (wt.%) as a baseline. Consistent with predictions from a recent Sn-Ag-Cu ternary phase-diagram study, either Sn dendrites, Ag₃Sn primary phase, or Cu₆Sn₅ primary phase were formed during solidification of joint samples made from the selected near-eutectic Sn-Ag-Cu alloys. Minor substitution of Co for Cu in Sn-3.7Ag-0.9Cu refined the joint-matrix microstructure by an apparent catalysis effect on the Cu₆Sn₅ phase, whereas Fe substitution promoted extreme refinement of the Sn-dendritic phase. Ambient-temperature shear strength was reduced by Sn dendrites in the joint microstructure, especially coarse dendrites in solute poor Sn-Ag-Cu, e.g., Sn-3.0Ag-0.5Cu, while Sn-3.7Ag-0.9Cu with Co and Fe additions have increased shear strength. At elevated (150°C) temperature, no significant difference exists between the maximum shear-strength values of all of the alloys studied.     

Radiolocation in CDMA Cellular System Based on Joint Angle and Delay Estimation

This paper considers the problem of wireless location in code-divisionmultiple-access (CDMA)cellular system. Through the method of jointly estimating angle of arrival(AOA) and time ofarrival (TOA), a novel scheme is proposed for radiolocation in multipathenvironment, especiallywhen line-of-sight (LOS) path is not available to every base station involvedin location servicefor a mobile subscriber. The Cramer-Rao bound (CRB) is derived for the jointestimator. Based onsimulation results, the accuracy of the proposed wireless location scheme inCDMA system is assessed.     

Joint Monitoring of Ground and Sky for Cereal Crops Based on Scatterometer Measurement and ASAR Images

The joint monitoring of the ground and sky for cereal crops based on microwave data has become a popular method for researches on earth surface objects. Focused on the sensitivity of backscatter from the scatterometer measurement and advanced synthetic aperture radar (ASAR) images to cereal parameters of rice, nine acquisitions, including rice parameters related eco-physiological variables and scattering coefficients, have been carried over the paddy field corresponding to rice growth stages. This paper analyzes the relationship between the corresponding backscatter to the cereal parameters based on the measurement at the interesting bands, polarizations, and incidence angels. Further, a modified water cloud model is built based on the ground measurement and advanced integrated equation model (AIEM), and then cereal parameters from ASAR images are retrieved and verified. The research results show that the sensitivity of backscatter to cereals from the sensor of the radar scatterometer could be helpful to build the retrieve model for synthetic aperture radar (SAR) images, which can achieve the scientific goals of the joint monitoring of ground and sky for cereal crops.     

IMT—Advanced协作多点传输技术——信道互异性校准

文章以协作多点传输技术为背景,基于信道互异性模型,介绍了3类较为典型的校准算法：基于硬件检测的自校准方法、基于天线自检测反馈的自校准方法、基于校准天线检测反馈的互校准方法。以此为基础,文章分析和研究了各校准算法的特性,评估和仿真了各校准算法协作多点传输技术在各类联合预编码算法下的系统性能,同时预测了校准算法未来的研究进程及可能面临的挑战。