数据拟合技术在变压器交流去磁试验分析中的应用

江苏500 kV泰兴变电所做2号主变交流去磁试验时出现了异常现象,即B相升压至80%额定电压以上时,电流表指针停在58格处不动。如何判断B相升压至90%及100%额定电压下,电流值是递增还是递减呢?运用数据拟合技术给出了所求之值,并对该方法的正确性结合实测值及理论分析给予验证,对解决同类型的试验问题具有一定的借鉴作用。     

High-speed ground moving target detection research using triangular modulation FMCW

The frequency modulated continuous wave (FMCW) radar has the characteristics of low probability of interception, good hidden property and the ability to counter anti-radiation missiles. This paper proposes a new method for high-speed ground moving target detection (GMTD) using triangular modulation FMCW. According to the characteristic of the opposite range shift induced by the upslope and downslope modulation FMCW, the upslope and downslope are imaged, respectively. After compensation of continuous motion of the platform and time difference between upslope and downslope signals for imaging, the moving target can be detected through displaced phase center antenna (DPCA) technology. When the moving target is detected, the moving target image is extracted, and correlation processing is used to obtain the range shift, which can be used to estimate the target radial velocity, and further to find the real position of the target. The effectiveness of this method is verified by the result of computer simulation. __________ Translated from Journal of Xidian University, 2008, 35(4): 586–591 [译自: 西安电子科技大学学报(自然科学版)]     

电力电子在微电网、智能电网、智能社区中的应用动向

为了可持续使用能源和保护地球环境,世界各国都在积极开发利用可再生能源。但可再生能源大量并网后会引发哪些新问题?未来的能源格局将如何变化?各国都还在探索之中。本文以富士电机的案例为基础,介绍该公司在新能源开发利用、微电网、智能电网、智能社区、能源管理、通信网络、电力稳定、供需平衡等方面的一些构想,从中导出电力电子的未来走向。     

B对Al-7Si合金а相形态和力学性能的影响

研究了B对Al-7Si合金а相形态和力学性能的影响.结果表明,B对Al-7Si合金具有良好的细化效果;初生а相的形态与大小发生显著变化,树枝晶消失,转变为细小的柱状晶.当加入0.036%B时,组织最理想:形态密实、尺寸细小而均匀,同时,合金的综合力学性能得到了显著的提高.抗拉强度提高15%、延伸率提高68%、断面收缩率提高46%,弹性模量和硬度分别降低22%和9%,细化后A1-7Si合金表现出良好的强韧性.     

二维三氧化钨纳米结构的合成及其在光电探测器中的应用

三氧化钨（WO₃）是制造晶体管和光电探测器的理想材料,虽然在WO₃纳米结构的生长方面已经完成了一些工作,但是制造足够长的理想型纳米线仍然是一个挑战。在众多的合成方法中,作者选择了化学气相沉积（CVD）方法合成WO₃纳米线,并对其在光电传感器中的应用进行了研究。影响WO₃纳米线成品率的主要因素是前体材料温度、基片位置、载气流速和生长持续时间。在合适的生长条件下生长的纳米线长度最长约为100 μm。这些WO₃纳米线可用来制造高性能的光电探测器,WO₃光电探测器具有灵敏度高、响应速度快、模块微型化等优良的器件性能,表明二维WO₃纳米线在光电探测器的制造中具有很大的优势。      

BT36高温钛合金的成分特点及组织研究

采用金相观察和扫描能谱分析的方法,测定了BT36合金的α+β/β相转变温度和组织中不同区域的成分.结果表明:BT36合金的α+β/β相转变温度为980℃.其轧棒经过两相区热处理可获得等轴组织,同时存在片层状的β转变组织.经测定,与周围等轴基体相比,片层中Al含量偏低,而Mo、W含量偏高,这是由于合金在熔炼时合金元素没有得到充分地均匀化.     

Antireflection and band gap extension effects of ZnO nanocrystalline films grown on ITO-coated glasses by low temperature process

Zinc oxide (ZnO) nanocrystalline films coated on indium tin oxides (ITO, 90:10 wt%) glasses were prepared by low temperature process. The thin films were composed of uniform nanoparticles with average diameter around 8.4 nm. All samples exhibited excellent optical antireflective phenomena, and the maximum transmission reached 92.8% for the sample spin coated at 1500 rpm at 453 nm, improved by 21.5%. The antireflective results were explained by the coherence theory. And the antireflective effects were induced by the ITO and ZnO films. The calculated thicknesses of the ZnO films agreed well with the experimental results. The theoretical calculated band gap from the average diameter of ZnO nanoparticles was also well consistent with the experimental ones obtained from the optical transmission spectra. This result was promising for applications in organic solar cells.     

Genome-Wide Association Study Identifies a Rice Panicle Blast Resistance Gene,Pb2, Encoding NLR Protein

Rice blast is one of the main diseases in rice and can occur in different rice growth stages. Due to the complicated procedure of panicle blast identification and instability of panicle blast infection influenced by the environment, most cloned rice resistance genes are associated with leaf blast. In this study, a rice panicle blast resistance gene, Pb2, was identified by genome-wide association mapping based on the panicle blast resistance phenotypes of 230 Rice Diversity Panel 1 (RDP1) accessions with 700,000 single-nucleotide polymorphism (SNP) markers. A genome-wide association study identified 18 panicle blast resistance loci (PBRL) within two years, including 9 reported loci and 2 repeated loci (PBRL2 and PBRL13, PBRL10 and PBRL18). Among them, the repeated locus (PBRL10 and PBRL18) was located in chromosome 11. By haplotype and expression analysis, one of the Nucleotide-binding domain and Leucine-rich Repeat (NLR) Pb2 genes was highly conserved in multiple resistant rice cultivars, and its expression was significantly upregulated after rice blast infection. Pb2 encodes a typical NBS-LRR protein with NB-ARC domain and LRR domain. Compared with wild type plants, the transgenic rice of Pb2 showed enhanced resistance to panicle and leaf blast with reduced lesion number. Subcellular localization of Pb2 showed that it is located on plasma membrane, and GUS tissue-staining observation found that Pb2 is highly expressed in grains, leaf tips and stem nodes. The Pb2 transgenic plants showed no difference in agronomic traits with wild type plants. It indicated that Pb2 could be useful for breeding of rice blast resistance.     

滚筒采煤机固有频率的计算机仿真

滚筒采煤机的固有频率影响着振动形式和振动烈度,因此采用计算机仿真方法得到一般滚筒采煤机前几阶固有频率值,根据得到的结果给出改善其振动特性的建议,为后续进一步研究奠定基础。     

Distribution of heavy metals during pyrolysis of waste printed circuit boards

The volatilization behavior of Cu, Pb, Sn, Sb, Ni, Zn, Mn, Co, Cr, Cd during pyrolysis of waste printed circuit boards was investigated in a bench-scale fixed-bed pyrolysis system. It was found that volatility of heavy metals increases with operating temperature elevating, and bromine and vacuum have an obvious promoting effect on volatility of most of heavy metals. Over 99% weight of Cu and Ni are still remained in solid residue after pyrolysis, about 20% weight of Sb, Zn and Cd are transfered into liquid and gas during a pyrolysis process at 600 ℃, volatilization fractions of Pb, Sn, Mn, Co, Cr are less than 10% at the same conditions. The contents of heavy metals in liquid and gas products depend on not only volatility of metals, but also their initial contents in printed circuit boards, pyrolysis liquid and gas are primarily contaminated by Cu, Pb, Sn, Sb and Zn, their contents in liquid vary from 10^2 to 10^3 pg/mL, Mn, Co, Cr, Cd were detected only at very low level, less than 10 μg/mL.