A new complexity metric for FH/SS sequences using fuzzy entropy

This paper presents a new complexity metric to evaluate the unpredictability of a frequencyhopping/spread-spectrum (FH/SS) sequence based on fuzzy entropy (FuzzyEn).According to the property of the FS/SS sequence,the definition of a fuzzy membership function for a complexity metric is presented and a basic theorem for FuzzyEn complexity is proved.Simulation and analytical results show that the proposed FuzzyEn works and can effectively discern the changing complexities of the FH/SS sequences,which are compa...     

Investigation on SAW properties of LGS and optimal cuts for high-temperature applications

A promising perspective for surface acoustic wave (SAW) device applications at high temperature has been opened by langasite (LGS). The SAW properties of LGS in singly and doubly rotated cuts at 250 degrees C are investigated. Three noticeable regions for SAW-cut orientations and propagation directions at high temperature are put forward and are defined by Euler angles [0 degrees, 20 degrees --> 50 degrees, 35 degrees --> 45 degrees], [0 degrees, 85 degrees --> 110 degrees, 0 degrees --> 5 degrees], and [0 degrees, 138 degrees --> 145 degrees, 20 degrees --> 23 degrees], respectively. The first region includes zero or comparatively reduced temperature coefficient of delay (TCD) (<2 ppm) and smaller electromechanical coupling factor (K2) (0.2%-0.35%); the second one exhibits higher K2 (0.35%-0.45%) and moderate TCD (<5 ppm); and the highest K2 (>0.45%) and larger TCD (25-30 ppm) characterize the last region. For some typical orientations within the above-mentioned three regions, the temperature dependency of SAW characteristics (up to 1000 degrees C) is discussed. The second region [0 degrees, 85 degrees --> 110 degrees, 0 degrees --> 5 degrees], especially the orientation [0 degrees, 90 degrees, 0 degrees], has better comprehensive characteristics of SAW and is more suitable for high-temperature applications. Therefore, we should give a top priority to the orientation [0 degrees, 90 degrees, 0 degrees] in the design of SAW devices operating at high temperature. Comparison between published experimental results and numerical predictions based on LGS constants and their temperature coefficients available in the literature reveals that the theoretical results of TCD under 250 degrees C are in agreement with the experimental ones (the relative error of TCD is within 10%).     

双向线性回归方法

工程上迫切需要在现场或当前数据较少的情况下,建立高精度和高可靠度的现场经验公式.文中利用当前或现场检测数据与历史或试验室数据存在的共性信息,给出双向线性回归方法.此方法不仅能利用现场检测数据的个性信息,还能有效、合理地使用历史或试验室数据,有效扩大当前或现场数据的样本量,得到高精度的现场经验公式,同时利用该公式还可以得到高置信度的推定结果.将文中方法运用于回弹法检测混凝土强度中,有效解决了现场测强曲线建立问题.     

Large-scale assembly of Cu/CuO nanowires for nano-electronic device fabrication

To improve the efficiency of nano-electronic device fabrication,a new method named floating electrical potential assembly is proposed to realize large-scale assembly of Cu/CuO nanowires.The simulation of floating electrical potential distribution on the micro-electrode chip is performed by COMSOL software,and the simulation result shows that the coupled electrical potential on the floating drain electrodes is very close to the original electrical potential applied on the gate electrode,which means that the method can provide di-electrophoresis(DEP)force for all the electrode pairs at one time,thus realizing large-scale assembly at one time.With Cu/CuO nanowires well dispersed and micro-electrode chip fabrication,nanowires assembly experiments are performed and the experimental results show that Cu/CuO nanowires are assembled at hundreds of micro-electrodes pairs at one time,and the success rate of nanowires assembly also reaches 90%.     

低质量流速绝热管内截面平均空泡率实验研究

汽液两相流空泡率实验与计算方法研究对于反应堆自然循环及事故分析具有重要意义,然而现有研究主要以高质量流速工况为主,已有的空泡率公式预测结果在低质量流速条件下也存在较大差异。为此,本文以单探头光学探针为主要测量手段,进行了低质量流速绝热工况空泡率实验研究,截面平均空泡率根据探针测量得出的局部空泡率在流道截面上积分计算得出。实验数据与已有空泡率计算公式进行了比较,表明低质量流速工况下多数公式预测结果偏高,而Chexal et al．、GE—Ramp以及Dix公式可得出非常满意的预测结果。综合Vijayan的研究结果,本文建议低质量流速空泡率计算中采用Chexal et al．的公式。     

Manipulation of gold coated microspheres using electrorotation

The electrorotation of microspheres coated with conductive surface is a novel and important technology for label-free biosensors. Using the electroless plating approach, the polystyrene microspheres with 15 μm and 25 μm in diameters were coated with 50 nm gold layer in thickness. The electrorotation experiments on those gold coated polystyrene microspheres (GCPMs) were carried out. The results showed that they rotated in the opposite direction of the electric field in a low frequency range (100-100 kHz), an...     

AutoCAD数据到ArcSDE的转换方法研究

数据转换是在对原始数据深入理解后数据信息的转换.本文详细阐述了AutoCAD数据文件向ArcSDE转换的两种方法:基于FME转换软件的转换以及基于Object ARX二次开发技术结合ArcSDE C API接口程序定制转换程序的转换.     

有线电视技术的发展趋势及其展望

本文针对我国有线电视技术的应用，对有线电视系统的基本组成和发展进行了概括和总结，并提出了有线电视系统主流技术的发展方向。     

网络教学中C程序设计填空题机器批改的实现

在现存的网络考试系统中，有关题型均为标准化试题，这对于需严格考察学生程序能力的程序设计考虑而言不太合适，本文从C语言的特点出发，探讨了机器自动批改C程序设计填空题的实现，提出了解决方案，并说明了需要进一步研制的问题。     

砂布轮抛光工艺参数对TC4材料切除深度影响规律研究

铣削成型的航空发动机整体叶盘,其叶片型面为空间自由曲面,曲率变化大,严重制约了抛光表面质量均匀一致性.为掌握砂布轮柔性抛光工艺参数对材料切除深度影响规律,基于"数控机床+柔性磨头+弹性磨具(砂布轮)"的抛光工艺装备,开展了TC4试件单因素抛光试验,分析了工艺参数对材料切除深度的影响规律,开展正交试验建立了材料切除深度预测模型;计算了材料切除深度对工艺参数相对灵敏度,结果表明材料切除深度对压缩量最敏感,对转速比较敏感,对进给速度敏感度一般,对粒度敏感度最小;最后开展了抛光实验,结果表明实际测量切除轮廓和预测轮廓基本一致,证明了预测模型是可靠的,能用于材料切除深度预测,为提高抛光表面质量一致性提供依据.