Application of ultrasonic detection for partial discharge to cable terminals

The mechanical properties, phase change energy storage, environmental protection, and recycling of building materials are extensively studied, but few studies focus on the mercury adsorption of different building materials. Five types of cement brick powder including foam concrete, red brick, aggregate and gravel as well as several standard concrete blocks were exposed to gaseous mercury in constant temperature to determine most vulnerable building material to mercury contamination and the contamination depth of concrete blocks.Results showed that small particle contributed to large mercury adsorption, however different performance was found amongvarious materials. Red brick was the likely to have strong adsorption capacity followed by foam concrete and gravel. For concrete block,the pollution mainly concentratedat the 0~1.5cm of the surface. As a result, for some seriously mercury polluted factories and workshops, mercury pollution can be removed by peeling the skin of the buildings before demolition, renovation process.     

Photoacoustic spectroscopy applied to the detection of SF6decomposition components under partial discharge

The traditional detection methods of SF6 decomposition components under partial discharge have some shortages,including consuming much detected gas,long detecting time,and unsuitable for on-line monitoring. While,photoacoustic spectroscopy has some advantages,including high sensitivity on detecting gas,and without consuming detected gas,etc. According to these reasons,the detection technology used in SF6 decomposition components under partial discharge is studied,and the feature spectrum of SO2,CO2 and CF4by SF6 decomposing is given. Through the photoacoustic spectroscopy device,the relation lines between photoacoustic spectroscopy(PAS) signal and concentration of gas components are obtained. The minimum detection limits of SO2,CO2 and CF4are about 3.8×10 -6,3.1×10 -6 and 4.7×10 -6 respectively. A method of RBF neural network is set up to reduce the crossover response of PAS signals of SO2,CO2 and CF4 mixed gas. It makes the average examination error of three gases reduce to 5.6%,1.6% and 3.3% respectively. Its reliability is checked by comparative testing of gas ehromatography and detector tube. The results indicate that the RBF neural network is useful in improving detection precision and provides a kind of technology to crossover response problem.     

Hilbert-Huang transform and denoising for partial discharge ultrsonic singals of large motor

Empirical mode decomposition (EMD) algorithm is introduded as the core of the Hilbert-huang transform (HHT), and implementation process of EMD is analyzed. Then data compression denoising algorithm based on EMD is proposed, simulation and experimental signals are used for verification of the effect of EMD. In the same data sources, the comparison of data compression denoising approaches based on the EMD, db2 wavelet and db8 wavelet are conducted. In addition, physical experiment of the same analysis and comparisons are conducted on a running motor in a Chongqing electrical plant. Simulation and experimental results show that data compression denoising algorithm based on EMD can achieve the same denoising effect, or even better than based on db2 wavelet, db8 wavelet. The former is more perfect than the latter in the real signal processing, and denoising based on EMD is not loss of the original signal energy.     

Analysis on the ultrasonic online location for partial discharge in the stator winding of generator

The propagation characteristics of the partial discharge’s ultrasonic signal in the stator of generator and the difference between the ultrasonic signal and the running background noise are analyzed with experiments. Ultrasonic online location for partial discharge is proven to be feasible. For non blind area monitoring, the stator is divided into several equal parts. Locating equations are established with electroacoustic detection method and optimized with genetic algorithm. The simulation results indicate that the proposed method of ultrasonic online location for the partial discharge in the stator of generator is correct.     

Characteristic analysis of partial discharge in high voltage XLPE cable accessories

Four physical models of typical internal insulation defects in 110 kV cable joints are designed and a test platform for partial discharge (PD) research on cable accessories also is constructed. Based on the models, plenty of PD data are obtained for vario     

Application of dynamic time warping algorithm to partial discharge pattern recognition

This study uses the data sequences of apparent charge versus applied voltage （ΔQ-U) in the process of stepping-up/down the voltage as the characteristic features of partial discharge (PD). Based on Dynamic time warping (DTW) algorithm, a method is introduced to realize PD pattern recognition for insulation defect models. In the training process of DTW classifier, the train and test samples are processed by vector quantization (VQ). Moreover, the original vectors are substituted by the codeword to realize data reduction, and the DTW reference templates of various PD types are constructed by the corresponding train samples. In the testing process, the average DTW distances between test samples and each reference templates are calculated based on the accumulated distances. Recognition results are obtained by the recognition rule of nearest neighbor. The new algorithm is also supported by Fast Match (FM) technique to speed up the DTW matching process. The recognition results from five PD sources and 200 samples demonstrate the high classification rates and easy expansion of the proposed DTW algorithm. FM algorithm can save 56 percent computational time and improve the classification rates.     

A floating threshold quantization algorithm to suppressmixing interferences in partial discharge

Due to the obvious difference of energy distribution frequencies from partial discharge (PD) signal and its mixing interferences (white noise and narrow brand), we uses the characteristic that node decomposition coefficients of wavelet packet transform can effectively show the energy change of signals to build up a floating threshold quantization algorithm (FTQA) varying with the noise energy of PD decomposition coefficients. It makes the node thresholds under the optimal base various with the noise strength in decomposition coefficients to self adaptively reality the choice of optimal threshold to finely partition PD decomposition coefficients. For simulated and real PD signals with mixing interferences, the conditional global threshold quantization algorithm (GTQA) and the proposed floating threshold quantization algorithm are employed to suppress the mixing interferences in PD signals and compared, and the results show that the proposed algorithm has the stronger suppression ability to mixing interference on PD signal and keeps perfect PD waveform via suppression.     

Characteristics of UHF partial discharge signal waveforms of typical insulated defects in GIS

In order to analyze the discharge features of different insulation defects in various experimental conditions, according to characteristics of partial discharge (PD) from the insulation defects in gas insulated switchgear (GIS)) and using ultra high frequency (UHF) method, a lot of PD experiments are carried out based on the designed four typical physical models of insulation defects of GIS in the simulation device, and the real samples of UHF PD waveforms are recorded. The features of UHF PD waveforms in the different situations are discussed and analyzed in detail, which include different sizes or positions of the physical models or under the different voltages and so on. The results show that in low voltage, regardless of types of UHF electromagnetic wave excited by PD sources, the shapes of PD waveform changed little before the changes of waveform. The remaining time is about several nanoseconds.     

菌落聚合酶链反应检测支气管败血波氏杆菌

根据支气管败血波氏杆菌(Bordetella bronchiseptica) 鞭毛蛋白基因的上游序列设计1对引物Fla1和Fla2,采用菌落PCR方法扩增目的基因片段来检测支气管败血波氏杆菌。利用该方法成功的从8株支气管败血波氏杆菌中扩增出237 bp左右的特异性目的片段。特异性试验表明,该方法对大肠埃希菌、胸膜肺炎放线杆菌、多杀性巴氏杆菌、猪链球菌和副猪嗜血杆菌均无交叉性反应。灵敏性试验表明,将单个菌落稀释105倍利用此菌落PCR仍能扩增到相应的目的片段。结果表明建立的菌落PCR方法对支气管败血波氏杆菌的检测敏感性高、特异性强,可用于Bb感染的诊断和流行病学调查。     

Classification of ultra high frequency partial discharge signalsin gas insulated switchgear based on complex wavelet transform

In order to classify the ultra high frequency (UHF) partial discharge (PD) signals resulting from four types of insulation defects in gas insulated switchgear (GIS), the complex wavelet transform is applied to extract features of UHF PD signals. Five statistical parameters including mean, variance, kurtosis, skewness and energy are used to quantize the scaling coefficients of the complex wavelet transform and describe the feature subsets of UHF PD signals.A critical index J is defined to select features according to their classification performance. Using the J criterion, five optimal features are selected from sixty UHF PD features and taken as the input of radial basis function neural network. The classification results show that the information of real part and image part of complex wavelet coefficients indicates the characteristics of UHF PD singles and the recognition effect is pretty good. To use db4 complex wavelet can get the best classification performance.     

马铃薯A病毒RT-LAMP检测方法的建立

马铃薯A病毒(potatovirusA,PVA)是一种侵染马铃薯的病毒,严重影响马铃薯的经济价值和产量,为有效防止该有害生物的传入和扩散,建立马铃薯A病毒RT-LAMP检测方法,根据PVA的外壳蛋白基因序列设计RT-LAMP反应的特异引物,通过实验成功建立了PVA的RT-LAMP特异性检测方法。该方法检测快速,36min即可检测到扩增曲线;特异性强,可有效区分同样侵染马铃薯的马铃薯A病毒(PVA)、马铃薯V病毒(PVV)、马铃薯Y病毒(PVY)以及同属的百合斑驳病毒(LMoV);灵敏度高,比普通RT-PCR灵敏度高10倍;并可通过肉眼观察浊度或颜色反应直接进行结果判断。该方法适用于现场PVA的快速检测。     

Development of multispectral imaging algorithm for detection of frass on mature red tomatoes

In this research, a multispectral fluorescence-based imaging algorithm was developed to detect frass contamination on mature Campari tomatoes. Tomato images were acquired using a hyperspectral fluorescence line-scan imaging system with violet LED excitation, then analyzed for wavelength selection. The fluorescence intensities at five wavelengths, 515 nm, 640 nm, 664 nm, 690 nm, and 724 nm, were used to compute three simple ratio functions to detect frass contamination. The contamination spots were created on the tomato surfaces using four low-concentration frass dilutions. The algorithms detected over 99% of the 0.2 kg/L and 0.1 kg/L frass contamination spots and successfully differentiated these spots from tomato skin surfaces, stem scars, and stems. However, differentiation of the 0.05 kg/L and 0.02 kg/L frass contamination spots was more difficult. Adjusting the algorithm to successfully detect 95% of the 0.05 kg/L spots also resulted in false-positive pixel detections occurring on 28% of the tomatoes. This study demonstrates that a simple multispectral fluorescence imaging algorithm based on violet LED excitation could be useful for rapid postharvest detection of frass contamination on tomatoes in processing lines.     

猪多杀性巴氏杆菌可视化LAMP检测方法的建立

该研究旨在建立一种快速检测猪多杀性巴氏杆菌的LAMP方法。根据GenBank中猪多杀性巴氏杆菌外膜蛋白H基因(ompH)序列,在其保守区域设计了多套LAMP引物,通过LAMP反应,评价其特异性和敏感性,并加入SYBR Green Ⅰ,对其进行肉眼判定。结果显示：建立的LAMP方法在56℃水浴中1 h可对猪多杀性巴氏杆菌核酸进行高效扩增,在反应结束后加入SYBR Green Ⅰ可肉眼进行判断;该方法具有很强的特异性,对其它相关猪病病原菌检测结果均为阴性;其DNA核酸的检测量为0.05pg,是PCR的100倍,显示出很高的敏感性;用建立的LAMP方法对5株猪多杀性巴氏杆菌阳性样品进行检测,结果表明LAMP法与PCR检测的结果是一致的。结果表明该研究建立了一种操作简便、快速、敏感、特异的可对猪多杀性巴氏杆菌进行快速检测并可肉眼判定结果的可视化LAMP方法,适合在基层使用。     

对称式基坑渗流涌水量的计算方法

随着地铁、越江隧道等地下工程的日益增多,涌现出了大量的对称式基坑。基于共形映射理论,推导了对称式基坑涌水量计算表达式,并对其计算参数进行分析。研究表明,对称式基坑的单宽涌水量与渗透系数、基坑内外水头差成正比,与（相对）隔水层层顶到坑底的距离和基坑两侧止水帷幕间距的比值、止水帷幕嵌固深度和（相对）隔水层层顶到坑底距离的比值、基坑内外水头差和（相对）隔水层层顶到坑底距离的比值成反相关。     

Development of PCR-based DNA marker for detection of white carrot contamination caused by Y2 locus

In carrot (Daucus carota L.), the taproot colors orange, yellow and white are determined mostly by the Y, Y2, and Or loci. One of the most severe issues in carrot seed production is contamination by wild white carrot. To evaluate the contamination ratio, easily detectable DNA markers for white carrot are desired. To develop PCR-based DNA markers for the Y2 locus, we have re-sequenced two orange-colored carrot cultivars at our company (Fujii Seed, Japan), as well as six white- and one light-orange-colored carrots that contaminated our seed products. Within the candidate region previously reported for the Y2 locus, only one DNA marker, Y2_7, clearly distinguished white carrots from orange ones in the re-sequenced samples. The Y2_7 marker was further examined in 12 of the most popular hybrid orange cultivars in Japan, as well as ‘Nantes’ and ‘Chantenay Red Cored 2’. The Y2_7 marker showed that all of the orange cultivars examined had the orange allele except for ‘Beta-441’. False white was detected in the orange-colored ‘Beta-441’. The Y2_7 marker detected white root carrot contamination in an old open-pollinated Japanese cultivar, ‘Nakamura Senkou Futo’. This marker would be a useful tool in a carrot seed quality control for some cultivars.     

调零天线中的空域极化域联合抗干扰算法

在期望信号功率较小情况下,强同频干扰容易造成系统灵敏度下降,比如卫星导航和卫星通信。采用一个4阵元正交极化阵列,可以通过空域和极化域联合方式对干扰进行抑制。阵列参考阵元位于圆心,其余3个阵元均匀分布在圆周上。自适应滤波采用功率倒置准则下的LMS算法,该方法调整每个正交极化阵元权系数,使得阵列在干扰极化下等效的极化匹配因子接近为0,实现干扰抑制。算法无需信号空间信息,实现简单,同时使阵列自由度达到6,从而增加抗干扰个数。计算机仿真证明了4个阵元阵列可以有效抑制最多6个干扰,而且,通过极化域处理,即使干扰信号与期望信号入射角度相同,只要极化不同,也可以抑制干扰而保持对期望信号增益。     

Small scale wind tunnel for high pressure and high energy discharge

A kind of small scale wind tunnel with low velocity is proposed according to the characteristics of strong ionization discharge chamber and the demands of discharge for flux, velocity and flow fields. On the precondition that the airflow field and velocity is satisfied, aerodynamic design and structural design are carried out. Key techniques are studied including overall structure, aerodynamic and structural design of airflow vent and collection vent, aerodynamic and structural design of power section, flow rate adjustment and control, and cooling system of motor. Based on the design scheme, a small scale wind tunnel with strong ionization discharge for an enterprise is developed. Application indicates that the small scale wind tunnel is a practical and effective airflow loop device for high pressure and strong ionization discharge with the features of stability and reliability.     

葡萄苦腐病菌的分子检测方法

葡萄苦腐病菌(Greeneria uvicola)是我国检疫性有害生物.本研究根据G.uvicola的ITS基因序列,设计了PCR引物GUA-1和GUA-2以及实时荧光PCR引物GUA-P1和GUA-P2及荧光探针GUA-Probe-117.利用引物GUA-1和GUA-2进行PCR扩增,G.uvicola和感染G.uvicola的红提葡萄可产生354 bp的特异性片段;实时荧光PCR扩增,G.uvicola和感染G.uvicola的红提葡萄均出现强荧光信号(△Rn)增加.而葡萄上其他常见真菌样品以及健康的红提葡萄既无特异性扩增也无荧光信号增加.灵敏度测试中,普通PCR可检测到含G.uvicola DNA浓度0.05ng/μL以上的样品,实时荧光PCR可检测到含G.uvicola DNA浓度0.0005 ng/μL以上的样品.由此确立了G.uvicola的两种稳定可靠、灵敏的分子检测方法.     

Design of anultra-wideband monopole antenna with dual band-notched function

In wireless communication systems,in order to overcome the mutual interference among systems,an UWB monopole antenna with dual band-notched characteristic is proposed using band-suppressed technology. Using the techniques of loading and slotting makes the returned loss of the antenna less than -10 dB in the band of 2.6~14.6 GHz. Through slotting on the ground plane and the radiating patch,VSWR is greater than 2 in the range of IEEE802.16 of 3.3~3.6 GHz,C-wave satellite communications system 3.7~4.2 GHz,and IEEE802.11a of 5.15~5.825 GHz frequency band. Results of simulation and test show that the antenna has good function of suppression,simple structure and small size.