检索结果-南通市图书馆

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第2期9卷 173-181页

作者： zhi-yong li Wei-lin WU School of Electrical Engineering Zhejiang University Hangzhou 310027 China

Power Quality (PQ) combined disturbances become common along with ubiquity of voltage flickers and harmonics. This paper presents a novel approach to classify the different patterns of PQ combined disturbances. The classification system consists of two parts, namely the feature extraction and the automatic recognition. In the feature extraction stage, Phase Space Reconstruction (PSR), a time series analysis tool, is utilized to construct disturbance signal trajectories. For these trajectories, several indices are proposed to form the feature vectors. Support Vector Machines (SVMs) are then implemented to recognize the different patterns and to evaluate the efficiencies. The types of disturbances discussed include a combination of short-term dis-turbances (voltage sags, swells) and long-term disturbances (flickers, harmonics), as well as their homologous single ones. The feasibilities of the proposed approach are verified by simulation with thousands of PQ events. Comparison studies based on Wavelet Transform (WT) and Artificial Neural Network (ANN) are also reported to show its advantages.

关键词： Power Quality (PQ) Combined disturbance Classification Phase Space Reconstruction (PSR) Support Vector Machines (SVMs)

Sodium-ion conducting polymer electrolytes

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2023年第1期42卷 1-16页

作者： zhi-yong li Zhuo li Jia-Long Fu Xin Guo State Key Laboratory of Material Processing and Die and Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan430074China

Almost unlimited reserves and low cost of sodium are accelerating the commercialization of sodiumion ***,serious safety and stability issues,arising mainly from organic liquid electrolytes,hinder further developments of sodium-ion *** electrolytes might be a solution to the safety and stability issues due to the better safety of ***,an overview is provided on recent advances in polymer electrolytes for solid-state sodium batteries,including solid polymer electrolytes,composite polymer electrolytes and gel polymer *** properties,ionic conduction mechanisms and promising applications of polymer electrolytes are discussed,and pending challenges and effective solutions are ***,this review will promote commercial applications of polymer electrolytes in energy storage systems.

关键词： Polymer electrolyte Ionic conductivity Ionic conduction mechanism Sodium-ion battery(SIB) Solidstate battery(SSB)

Application of land use regression for estimating concentrations of major outdoor air pollutants in Jinan, China

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2010年第11期11卷 857-867页

作者： li CHEN Shi-yong DU zhi-peng BAI Shao-fei KONG Yan YOU Bin HAN Dao-wen HAN zhi-yong li College of Environmental Science and Engineering Nankai University Tianjin 300071 China State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution and Control Tianjin 300071 China College of Urban and Environmental Science Tianjin Normal University Tianjin 300387 China Jinan Institute of Environmental Sciences Jinan 250014 China

SO2, NO2, and PM10 are the major outdoor air pollutants in China, and most of the cities in China have regulatory monitoring sites for these three air pollutants. In this study, we developed a land use regression (LUR) model using regulatory monitoring data to predict the spatial distribution of air pollutant concentrations in Jinan, China. Traffic, land use and census data, and meteorological and physical conditions were included as candidate independent variables, and were tabulated for buffers of varying radii. SO2, NO2, and PM10 concentrations were most highly correlated with the area of industrial land within a buffer of 0.5 km (R2=0.34), the distance from an expressway (R2=0.45), and the area of residential land within a buffer of 1.5 km (R2=0.25), respectively. Three multiple linear regression (MLR) equations were established based on the most significant variables (plied to an area with complex terrain. The buffer radii of independent variables for SO2, NO2, and PM10 were chosen to be 0.5, 2, and 1.5 km, respectively based on univariate models. Intercepts of MLR equations can reflect the background concentrations in a certain area, but in this study the intercept values seemed to be higher than background concentrations. Most of the cities in China have a network of regulatory monitoring sites. However, the number of sites has been limited by the level of financial support available. The results of this study could be helpful in promoting the application of LUR models for monitoring pollutants in Chinese cities.

关键词： Land use regression (LUR) Air pollution Background concentration Geographic information system (GIS)

Unitary transformation of general nonoverlapping-image multimode interference couplers with any input and output ports

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2020年第1期29卷 287-292页

作者： Ze-Zheng li Wei-Hua Han zhi-yong li College of Materials Science and Opto-Electronic Technology University of Chinese Academy of SciencesChinese Academy of SciencesBeijing 100049China State Key Laboratory on Integrated Optoelectronics Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China

An explanation of optical unitary transformation is presented for general nonoverlapping-image multimode interference(MMI)couplers with any number of input and output *** light transformation in the MMI coupler can be considered as an optical field matrix acting on an input light column *** investigate the general phase principle of output light *** complete proof of nonoverlapping-image MMI coupler’s optical unitarity along with the phase analysis of matrix element is *** on a two-dimensional finite-difference time-domain(2 D-FDTD)simulation,the unitary transformation is obtained for a 4×4 nonoverlapping-image MMI coupler within a deviation of 4×10-2 for orthogonal invariance and 8×10-2 for transvection invariance in the C-band spectral range.A compact 1×4 splitter based on cascaded MMI coupler is proposed,showing a phase deviation less than 5.4°while maintaining a low-loss performance in C-band spectra.

关键词： multimode interference coupler optical unitary transformation integrated photonics

Ballistic penetration damages of hybrid plain-woven laminates with carbon,Kevlar and UHMWPE fibers in different stacking sequences

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2023年第8期26卷 23-38页

作者： zhi-yong li You-song Xue Bao-zhong Sun Bo-hong Gu Shanghai Frontier Science Research Center for Modern Textiles College of TextilesDonghua UniversityShanghai201620China

Hybrid composite materials combine different fibers in preform and take advantages of different mechanical behaviors for improving ballistic impact damage *** we report ballistic impact damages of plain-woven laminates with different hybrids and stacking *** kinds of hybrid laminates,i.e.,carbon/Kevlar,carbon/ultra-high molecular weight polyethylene(UHMWPE),and UHMWPE/Kevlar,had been prepared and tested in ballistic penetration with fragment simulating projectiles(FSP).The residual velocities of the projectiles and impact damage morphologies of the laminates have been obtained to show impact energy absorptions for the different hybrid schemes.A microstructural model of the hybrid laminates had also been established to show impact damage mechanisms with finite element analysis(FEA).We found that the UHMWPE/Kevlar hybrid laminates with Kevlar layers as the front face have the highest energy absorption capacity,followed by the carbon/Kevlar hybrid laminates with carbon layers as the front *** main damage modes are fiber breakages,matrix crack and interlayer *** ballistic damage evolutions from the FEA results show that the major damage is shear failure for front layers,while tension failure for the back *** expect that the ballistic impact performance could be improved from the different hybrid schemes.

关键词： Hybrid laminates Ballistic impact damages Energy absorption Finite element analysis(FEA)

Exit morphology and mechanical property of FDM printed PLA: influence of hot melt extrusion process

在线全文

学校读者我要写书评

暂无评论

Advances in Manufacturing 2023年第1期11卷 56-74页

作者： Yan-Hua Bian Gang Yu Xin Zhao Shao-Xia li Xiu-li He Chong-Xin Tian zhi-yong li Institute of Mechanics Chinese Academy of SciencesBeijing100190People’s Republic of China School of Engineering Science University of Chinese Academy of SciencesBeijing100049People’s Republic of China Research Institute of 3D Printing Beijing City UniversityBeijing100083People’s Republic of China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing100049People’s Republic of China

In order to study the hot melt extrusion process in fused deposition modeling(FDM),this study mainly explores the effects of printing temperature,heated block length,feeding speed on the exit morphology and mechanical properties of FDM printed Polylactic acid(PLA)***-speed camera is used to capture the exit morphology of molten PLA just extruded to the *** to exit morphology,the outlet states of extruded molten material can be divided into four categories,namely,bubbled state,coherent state,expanding state,and unstable *** test results show that printing temperature,heated block length and printing speed have significant influence on tensile properties and fracture mode of FDM printed *** the heated block length is 15 mm and 30 mm,there is a ductile-brittle transition in fracture mode with the increase of printing *** printing process window under different heated block lengths and printing temperatures has been figured out and the distribution of printing process window under different printing speeds has been *** is a maximum printing process window under the heated block length of 30 *** finding provides a frame work for performance prediction of FDM printed parts and theoretical guidance for expanding the scope of printing process window.

关键词： Fused deposition modeling(FDM) Polylactic acid(PLA) Exit morphology Tensile property Printing process window

Low insertion loss silicon-based spatial light modulator with high reflective materials outside Fabry–Perot cavity

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

Chinese Physics B 2019年第10期28卷 376-380页

作者： li-Fei Tian Ying-Xin Kuang Zhong-Chao Fan zhi-yong li State Key Laboratory on Integrated Optoelectronics Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China Engineering Research Center for Semiconductor Integrated Technology Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China

The extinction ratio and insertion loss of spatial light modulator are subject to the material problem, thus limiting its applications. One reflection-type silicon-based spatial light modulator with high reflective materials outside the Fabry-Perot cavity is demonstrated in this paper. The reflectivity values of the outside-cavity materials with different film layer numbers are simulated. The reflectivity values of 6-pair Ta2O5/SiO2 films at 1550 nm are experimentally verified to be as high as 99.9%. The surfaces of 6-pair Ta2O5/SiO2 films are smooth: their root-mean-square roughness values are as small as 0.53 nm. The insertion loss of the device at 1550 nm is only 1.2 dB. The high extinction ratio of the device at 1550 nm and 11 V is achieved to be 29.7 dB. The spatial light modulator has a high extinction ratio and low insertion loss for applications.

关键词： spatial light modulator high reflective materials silicon-based Fabry-Perot cavity

Soil organic carbon contents, aggregate stability,and humic acid composition in different alpine grasslands in Qinghai-Tibet Plateau

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2016年第11期13卷 2015-2027页

作者： CAO zhi-yuan WANG yong li Jie ZHANG Jin-jing HE Nian-peng Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China

Alpine grassland soils on Qinghai-Tibet Plateau store approximately 33.5 Pg of organic carbon(C) at 0–0.75 m depth and play an important role in the global carbon *** investigated soil organic C(SOC),water-soluble organic C(WSOC),easily oxidizable organic C(EOC),humic C fractions,aggregate-associated C,aggregate stability,and humic acid(HA) composition along an east-west transect across Qinghai-Tibet Plateau,and explored their spatial patterns and controlling *** contents of SOC,WSOC,EOC,humic C fractions and aggregate-associated C,the proportions of macroaggregates(2-0.25) and micro-aggregates(0.25-0.053 mm),and the aggregate stability indices all increased in the order alpine desert liphatic C/aromatic C ratio of HA increased as alpine desert lity indices along this *** all these C fractions,SOC content and aggregate stability were more closely associated with humic C and silt and clay sized C in comparison with WSOC,EOC,and macro- and microaggregate *** results suggested that alpine meadow soils containing higher SOC exhibited high soil aggregation and aggregate *** annual precipitation should be the main climate factor controlling the spatial patterns of SOC,soil aggregation,and aggregate stability in this *** resistant and stable C fractions rather than labile C fractions are the major determinant of SOC stocks and aggregate stability.

关键词： Soil organic carbon Aggregate stability Humic acid Carbon-13 nuclear magnetic resonance Latitudinal transect Qinghai-Tibet Plateau

Easily-handled method to isolate mesenchymal stem cells from coagulated human bone marrow samples

在线全文

学校读者我要写书评

暂无评论

World Journal of Stem Cells 2015年第8期7卷 1137-1144页

作者： Heng-Xiang Wang zhi-yong li zhi-Kun Guo Zi-Kuan Guo Department of Hematology General Hospital of Air Force Key and Open Lab for Tissue Regeneration Xinxiang Medical University Department of Experimental Hematology Beijing Radiation Medicine

AIM:To establish an easily-handled method to isolate mesenchymal stem cells(MSCs) from coagulated human bone marrow samples. METHODS: Thrombin was added to aliquots of seven heparinized human bone marrow samples to mimic marrow coagulation. The clots were untreated,treated with urokinase or mechanically cut into pieces before culture for MSCs. The un-coagulated samples and the clots were also stored at 4 ℃ for 8 or 16 h before the treatment. The numbers of colony-forming unit-fibroblast(CFU-F) in the different samples were determined. The adherent cells from different groups were passaged and their surface profile was analyzed with flow cytometry. Their capacities of in vitro osteogenesis and adipogenesis were observed after the cells were exposed to specific inductive ***: The average CFU-F number of urokinasetreated samples(16.85 ± 11.77/106) was comparable to that of un-coagulated control samples(20.22 ± 10.65/106,P = 0.293),which was significantly higher than those of mechanically-cut clots(6.5 ± 5.32/106,P like in morphology and homogenously positive for CD44,CD73 and CD90,and negative for CD31 and CD45. Also,they could be induced to differentiate into osteoblasts and adipocytes in vitro. CONCLUSION: Urokinase pretreatment is an optimal strategy to isolate MSCs from human bone marrow samples that are poorly aspirated and clotted.

关键词： Coagulated marrow sample Mesenchymal stem cells Is

Microscopic characterization and formation mechanisms of deep-water sandy-debris-flow and turbidity-current sandstones in a lacustrine basin： a case study in the Yanchang Formation of the Ordos Basin, China

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

Petroleum Science 2018年第1期15卷 28-40页

作者： Jian-Bo liao Ai-Hua Xi zhi-yong li Hua-Qing liu Xiang-Bo li Rong Wanyan School of Geoscience and Technology Southwest Petroleum University Chengdu 610500 Sichuan China Petro China Research Institute of Petroleum Exploration &Development-Northwest Lanzhou 730020 Gansu China Key Laboratory of Reservoir Description CNPCLanzhou 730020 Gansu China

Deep-water deposition is a current issue in sedimentological research. Sandy-debris-flow sandstones and turbidity-current sandstones are the main types of sandstone that are the focus of considerable disputes in this research. Previous studies mainly focused on description of the macroscopic sedimentary structure and theoretical derivation of the formation mechanisms. The microscopic petrological characteristics, reservoir properties, and formation mechanisms of deep-water sandy-debris-flow and turbidity-current sandstones have been studied in the Yanchang Formation of the Ordos Basin,China, by means of field outcrop surveys, thin-section identification, geochemical element analysis, and porosity and permeability measurements under overburden pressure. The content of detrital grains in the sandy-debris-flow sandstones is high, whereas the contents of mica sheets and matrix are low. The fine-grained matrix is distributed unevenly within the pores. A considerable number of residual intergranular pores are preserved in the middle of single sand bodies, resulting in relatively better reservoir properties. The total number of detrital grains in the turbidite sandstone is low, while it contains abundant mica sheets and matrix. The mica sheets and fine-grained matrix are distributed evenly within the pores, resulting in serious damage to pores and poor reservoir properties. The sandy-debris-flow sandstones in the center of the lake basin form a high-quality reservoir; thus, this area is suitable for oil and gas exploration.

关键词： Sandy debris flow Turbidite Ordos Basin Petrology Reservoir properties