检索结果-南通市图书馆

Application of wavelet support vector regression on SAR data de-noising

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2011年第4期22卷 579-586页

作者： Yi Lin shaoming zhang Jianqing Cai Nico Sneeuw Research Center of Remote Sensing and Spatial Technology Tongji University Shanghai 200092 P. R. China Institute of Geodesy University of Stuttgart D-70174 Stuttgart Germany

A new filtering method for SAR data de-noising using wavelet support vector regression （WSVR） is developed. On the basis of the grey scale distribution character of SAR imagery, the logarithmic SAR image as a noise polluted signal is taken and the noise model assumption in logarithmic domain with Gaussian noise and impact noise is proposed. Based on the better per- formance of support vector regression （SVR） for complex signal approximation and the wavelet for signal detail expression, the wavelet kernel function is chosen as support vector kernel func- tion. Then the logarithmic SAR image is regressed with WSVR. Furthermore the regression distance is used as a judgment index of the noise type. According to the judgment of noise type every pixel can be adaptively de-noised with different filters. Through an approximation experiment for a one-dimensional complex signal, the feasibility of SAR data regression based on WSVR is con- firmed. Afterward the SAR image is treated as a two-dimensional continuous signal and filtered by an SVR with wavelet kernel function. The results show that the method proposed here reduces the radar speckle noise effectively while maintaining edge features and details well.

关键词： synthetic aperture radar (SAR) support vector regres-sion (SVR) kernel function wavelet analysis function approximation.

Research on Producing Al-Pb Alloy Plate by Liquid Dynamic Compacting

在线全文

学校读者我要写书评

暂无评论

Rare Metals 1990年第1期10卷 34-38页

作者： Xing, Zhaojie Chai, Guocai zhang, shaoming General Research Inst for Non-ferrous Metals China

Possibility of making Al-Pb alloy plate with Pb dispersed uniformly by LDC (Liquid Dynamic Compact) technology has been studied in the present paper. The relationship among the distance between nozzle and cooled base plate and the atomization pressure as well as the density of the Al-Pb alloy slab is measured. The relative density of the LDC Al-Pb alloy slab can reach 90% under condition of the present experiment. Microstructure of the slab consist of equal axial grains with 15 approximately 25 μm in diameter and Pb dispersed uniformly in them. After cold or hot rolling of the slab with reduction of 50 approximately 60%, the microstructure can be densified. The rolled Al-Pb alloy plate can be compacted together with pure Al plate very well.

关键词： Aluminum Metallography Microstructures Lead Metallography Segregation Metallography Recrystallization Plates Production Powder Metal Products Compacting

PREPARATION OF ROUND BILLETS BY SPRAY FORMING TECHNOLOGY

在线全文

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 1999年第2期9卷 98-102页

作者： Xiong, Baiqing zhang, Yong'an Lin, Yaojun zhang, shaoming Shi, Likai Beijing General Research Inst for Nonferrous Metals Beijing China

１ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｓｐｒａｙｆｏｒｍｉｎｇｔｅｃｈｎｏｌｏｇｙｉｓａｎｅｗｔｅｃｈｎｏｌｏｇｙｆｏｒｍａｋｉｎｇｍａｔｅｒｉａｌｓ．Ｉｔｈａｓｂｅｅｎｄｅｖｅｌｏｐｅｄｏｎｔｈｅｂａｓｉｓｏｆｔｈｅｃ... 详细信息

１ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｓｐｒａｙｆｏｒｍｉｎｇｔｅｃｈｎｏｌｏｇｙｉｓａｎｅｗｔｅｃｈｎｏｌｏｇｙｆｏｒｍａｋｉｎｇｍａｔｅｒｉａｌｓ．Ｉｔｈａｓｂｅｅｎｄｅｖｅｌｏｐｅｄｏｎｔｈｅｂａｓｉｓｏｆｔｈｅｃｏｎｖｅｎｔｉｏｎａｌｒａｐｉｄｓ...

关键词： spray forminground billetsnumerical methodratio of gas flux to melt flux

Break-up Process of Perturbed Molten Metal Jet and Preparation of Lead-Free Solder Balls

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2004年第z2期22卷 174-177页

作者： He Lijun zhang Shuguang zhang shaoming Xu Jun Shi Likai National Engineering Research Center for Non-Ferrous Metals Composites General Research Institute for Non-Ferrous MetalsBeijing 100088China

Solder balls, which are used in advanced electronics packages such as BGA (Ball Grid Array) and CSP (Chip Scale Package) to substitute the leads and realize the electrical and mechanical connections between substrate and chip,have severe specifications in diameter tolerance, roundness and surface quality, and therefore challenge the traditional technologies for fabrication of metallic particles and powders. The present work made a survey of perturbed molten metal jet break-up process, observed the formation and growth of capillary wave of tin-lead melt jet by way of rapid solidification, and on the basis of the above research, successfully obtained tin-lead eutectic and Sn-4.0Ag-0.5Cu lead free solder balls with tight distribution and good sphericity of particles through optimization of processing parameters, forming a solid base for cost effectively producing solder balls.

关键词： solder balls jet break-up capillary wave perturbation

Geometric active contour based approach for segmentation of high-resolution spaceborne SAR images

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2015年第1期26卷 69-76页

作者： shaoming zhang Fang He Yunling zhang Jianmei Wang Xiao Mei Tiantian Feng College of Surveying Mapping and Geo-Informatics Tongji University Institute of Remote Sensing and Digital Earth Chinese Academy of Sciences

Segmentation is the key step in auto-interpretation of high-resolution spaceborne synthetic aperture radar（SAR） images. A novel method is proposed based on integrating the geometric active contour（GAC） and the support vector machine（SVM）models. First, the images are segmented by using SVM and textural statistics. A likelihood measurement for every pixel is derived by using the initial segmentation. The Chan-Vese model then is modified by adding two items： the likelihood and the distance between the initial segmentation and the evolving contour. Experimental results using real SAR images demonstrate the good performance of the proposed method compared to several classic GAC models.

关键词： image segmentation synthetic aperture radar(SAR) imagery support vector machine(SVM) geometric active contour(GAC)

Preparation of tube blanks by atomization deposition process

在线全文

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 1999年第3期9卷 472-476页

作者： Xiong Baiqing(熊柏青) zhang Yongan(张永安) Lin Yaojun(林耀军) zhang shaoming(张少明) Shi Likai(石力开) Gen Res Inst NonFerrous Met Beijing 100088 Peoples R China

By using the method of mathematical calculation combined with experiment, the technological conditions of atomization deposition process for making tube blanks with even thickness were studied. The results show that in the case of the substrate rotating and translating simultaneously, when the ratio of the rotation frequency to the translational velocity is very large, and the other deposition conditions are suitable, tube blanks with even thickness and high density can be produced, and the actual deposition efficiency will be highest.

关键词： atomization deposition process tube blanks rotation frequency translational velocity Document code:A

Tensile and Fracture Properties of 15 vol% SiC_p/2009Al Composites Fabricated by Hot Isostatic Pressing and Hot Extrusion Processes

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2014年第5期27卷 875-884页

作者： Junhui Nie Jianzhong Fan shaoming zhang Shaohua Wei Tao Zuo Zili Ma Zhaobing Xiang General Research Institute for Nonferrous Metals

15 vol% silicon carbide particle （SiCp）-reinforced 2009A1 matrix （15 vol% SiCp/2009A1） composites were fabricated by hot isostatic pressing （HIP） and hot extrusion processes. The tensile and fracture properties of 15 vol% SiCp/ 2009Al were studied. The results showed that hot extrusion increased the ultimate tensile strength （UTS）, yield strength （YS）, elongation （EL）, reduction in area （RA）, and fracture toughness of the composites. The heat treatment resulted in the increase in UTS, YS, and fracture toughness, but a decrease in EL and RA. Both hot extrusion and heat treatment had negligible effects on elastic modulus （E）. With the increase of SiCp size, the UTS, YS, and E decreased, but the EL and RA increased. The fracture toughness increased first and then decreased with increasing SiCp size, and when the SiCp size was about 7 μm, the composites obtained the maximum fracture toughness value of 31.74 MPa m^1/2.

关键词： Aluminum matrix composites Silicon carbide Tensile properties Facture toughness Particle size

Droplet deposition and efficiency of fungicides sprayed with small UAV against wheat powdery mildew

在线全文

学校读者我要写书评

暂无评论

International Journal of Agricultural and Biological Engineering 2018年第2期11卷 27-32页

作者： Weicai Qin Xinyu Xue shaoming zhang Wei Gu Baokun Wang Nanjing Research Institute for Agricultural Mechanization Ministry of AgricultureNanjing 210014China Jiangsu Province Plant Protective Station Nanjing 210036China

Small unmanned aerial vehicle(UAV),a timely and effective pesticide sprayer,can be used to spray pesticide in a high efficiency without harming the crop,and is especially suitable for spraying for small farms and hills in Asian *** recent years,it has been chosen as a key and new technique for pesticide *** paper studied the impact of UAV(UAV N-3)spraying parameters(different working height and different spraying concentrations)on the deposition of droplets on the wheat canopy and the prevention of powdery *** sensitive paper was used as the sampler to collect the pesticide droplets and image processing software Deposit Scan was used to compute the coverage rate of droplets on the wheat top layer to acquire the proportional distribution of droplets on the wheat lower *** experimental results showed the impact of spraying height on the distribution of droplets on the wheat upper layer was quite significant,when the spraying height was 5.0 m and the spraying speed was 4 m/s,the coverage rate of droplets on the wheat lower layer was the largest,as it was 45.6%of that on the upper layer,the droplets distribution was the most uniform,and the coefficient of variation was 33.13%.450 g/hm^(2)(dosage registered)of triadimefon SC(44%)was sprayed by the UAV,the control efficiency reached 55.1%after applying which was better than 20%and 40%of dosage decreased for each hectare,and the applying effect(35.6%)of 20%dosage decreased for each hectare had no significant difference from the applying effect(34.6%)applied by a knapsack-type electric *** 10 d after applying,the prevention effect realized by UAV was lower than that realized by a knapsack-type electric sprayer,and it may be correlated to the meteorological condition and water amount in the pesticide ***,when UAV spraying was chosen to prevent wheat powdery mildew under a serious disease situation,an auxiliary agent for spraying could be added to prolong the retention of p

关键词： unmanned aerial vehicle(UAV) spraying pesticide parameters optimization fungicide deposition wheat powdery mildew control effect

Effect of closed-couple gas atomization pressure on the performances of Al-20Sn-1Cu powders

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2008年第4期27卷 439-443页

作者： ZHAO Xinming XU Jun ZHU Xuexin zhang shaoming National Engineering and Technological Research Center for Non-ferrous Metals Composites General Research Institute for Nonzferrous Metals Beijing 100088 China

Al-20Sn-1Cu powders were prepared by gas atomization in an argon atmosphere with atomizing pressures of 1.1 and 1.6 MPa. The characteristics of the powders are determined by means of dry sieving, scanning electron microscopy （SEM）, optical microscopy （OM）, and X-ray diffractometry （XRD）. The results show that the powders exhibit a bimodal size distribution and a higher gas pressure results in a broad size distribution. All particles in both cases are spherical or nearly spherical and satellites form on the surface of coarse particles. Dendritic and cellular structures coexist in the particle. With decreasing particle diameter, the secondary dendrite arm spacing （SDAS） decreases and the cooling rate increases. The particles processed under high gas atomization pressure （1.6 MPa） exhibit a lower SDAS value and a higher cooling rate than those of the same size under low gas atomization pressure （1.1 MPa）. The XRD results show that the Sn content increases with decreasing particle size.

关键词： powder production Al-Sn-Cu alloy gas atomization rapid solidification particle size distribution