检索结果-南通市图书馆

Dependence of low redshift Type Ia Supernovae luminosities on host galaxies

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2013年第9期13卷 1087-1096页

作者： Wen-Ke liang jian-Cheng Wang National Astronomical Observatories/Yunnan Observatory Chinese Academy of Sciences Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences University of Chinese Academy of Sciences

We study the relation between Type Ia Supernovae （SNe Ia） and properties of their host galaxies using a large sample with low redshift. By examining the Hubble residuals of the entire sample from the best-fit cosmology, we show that SNe Ia in passive hosts are brighter than those in star-forming hosts after light curve correction at the 2. 1σ confidence level. We find that SNe Ia in high luminosity hosts are brighter after light-curve correction at the 〉 3σ confidence level. We also find that SNe Ia in large galaxies are brighter after light-curve correction at the ≥2σ confidence level. We demonstrate that the residuals depend linearly on host luminosity at a confidence of 4or or host size at a confidence of 3.3σ.

关键词： supernovae: general -- distance scale -- galaxies: classification

Programmed cell death may act as a surveillance mechanism to safeguard male gametophyte development in Arabidopsis

在线全文

学校读者我要写书评

暂无评论

Protein & Cell 2011年第10期2卷 837-844页

作者： jian Zhang Chong Teng Yan liang State Key Laboratory of Plant Genomics and National Plant Gene Research Center(Beijing) Institute of Genetics and Developmental BiologyChinese Academy of SciencesBeijing 100101China

Programmed cell death(PCD)plays an important role in plant growth and development as well as in stress *** male gametophyte development,it has been proposed that PCD may act as a cellular surveillance mechanism to ensure successful progression of male gametogenesis,and this suicide protective machinery is repressed under favorable growth ***,the regulatory mechanism of male gametophyte-specific PCD remains ***,we report the use of a TdT-mediated dUTP nick-end labelingbased strategy for genetic screening of Arabidopsis mutants that present PCD phenotype during male gametophyte *** using this approach,we identified 12 mutants,designated as pcd in male gametogenesis(pig).pig mutants are defective at various stages of male gametophyte development,among which nine pig mutants show a microspore-specific PCD phenotype occurring mainly around pollen mitosis I or the bicellular *** PIG1 gene was identified by map-based cloning,and was found to be identical to ATAXIA TELANGIECTASIA MUTATED(ATM),a highly conserved gene in eukaryotes and a key regulator of the DNA damage *** results suggest that PCD may act as a general mechanism to safeguard the entire process of male gametophyte development.

关键词： programmed cell death male gametophyte PIG TdT-mediated dUTP nick-end labeling ATM

Preparation of SiC_p/Al_2O_3-Al Composites by Directed Metal Oxidation

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2006年第B12期19卷 47-50页

作者： LIN Ying YANG Hai-bo WANG fen ZHU jian-feng School of Materials Science and Engineering Shaanxi University of Science ＆ Technology Xianyang 712081 China

SiCp/Al2O3-Al composites were synthesized by means of direct metal oxidation method. The composition and microstructures of the composites were investigated using X-ray diffraction （XRD）, scanning electron microscopy （SEM） and metallurgical microscope. The effects of technical parameters on the properties of the product were analyzed. The results indicate that the composite possesses a dense microstructure, composed of three interpenetrated phases. Of them, SiO2 layer prohibits the powdering of the composites; Mg promotes the wetting and infiltration of the system and Si restricts the interfacial reaction while improving the wetting ability between reinforcement and matrix.

关键词： SiCD/Al2O3-Al composites: directed metal oxidation Al-Mg-Si alloy SiC reinforcement

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2020年第5期63卷 943-957页

作者： Shiru Zhang Zhiyao liang jian Lin Faculty of Information Technology Macao University of Science and TechnologyMacao Management Information Systems University of Houston-Clear LakeHouston77058USA

Calculating the semantic similarity of two sentences is an extremely challenging *** propose a solution based on convolutional neural networks(CNN)using semantic and syntactic features of *** similarity score between two sentences is computed as ***,given a sentence,two matrices are constructed accordingly,which are called the syntax model input matrix and the semantic model input matrix;one records some syntax features,and the other records some semantic *** experimenting with different arrangements of representing the syntactic and semantic features of the sentences in the matrices,we adopt the most effective way of constructing the ***,these two matrices are given to two neural networks,which are called the sentence model and the semantic model,*** convolution process of the neural networks of the two models is carried out in multiple *** outputs of the two models are combined as a vector,which is the representation of the ***,given the representation vectors of two sentences,the similarity score of these representations is computed by a layer in the *** results show that our algorithm(SSCNN)surpasses the performance MPCPP,which noticeably the best recent work of using CNN for sentence similarity *** with MPCNN,the convolution computation in SSCNN is considerably *** on the results of this work,we suggest that by further utilization of semantic and syntactic features,the performance of sentence similarity measurements has considerable potentials to be improved in the future.

关键词： Sentence similarity neural network convolutional neural networks

Aggregate Characteristics During Natural Revegetation on the Loess Plateau

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

Pedosphere 2008年第6期18卷 809-816页

作者： AN Shao-Shan HUANG Yi-Mei ZHENG fen-Li YANG jian-Guo State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water Conservation Chinese Academy of Sciences and Ministry of Water Resources Yangling 712100 （China） Northwest Agriculture and Forestry University Yangling 712100 （China） College of Water Conservancy and Civil Engineering China Agricultural University Beijing 100083 （China） Institute of Agricultural Resources and Environment Ningxia Academy of Agriculture and Forestry Sciences Yinchuan 750002 （China）

Field investigations and laboratory analysis were conducted to study the characteristics of soil water-stable aggregates during vegetation rehabilitation in typical grassland soils of the hilly-gullied loess area. The relationship between water- stable aggregates and other soil properties was analyzed using canonical correlation analysis and principal component analysis. The results show that during the natural revegetation, the aggregates 〉 5 mm dominated and constituted between 50% and 80% of the total soil water-stable aggregates in most of the soil layers. The 2-5 mm aggregate class was the second main component. The mean value of water-stable aggregates 〉 5 mm within the 0-2 m soil profile under different plant communities decreased in the following order： Stipa grandis 〉 Stipa bungeana Trin. 〉 Artemisia sacrorum Ledeb. 〉 Thymus mongolicus Ronn. 〉 Hierochloe odorata （L.） Beauv. Clay, organic matter, and total N were the key factors that influenced the water stability of the aggregates. Total N and organic matter were the main factors that affected the water stability of the aggregates 〉 5 mm and 0.5-1 mm in size. The contents of Fe2O3, Al2O3, and physical clay （〈 0.01 mm） were the main factors which affected the water stability of the 1-2 and 0.25-0.5 mm aggregates.

关键词： canonical correlation analysis loess area natural revegetation principal component analysis soil water- stable aggregates

A spatial resolution effect analysis of remote sensing bathymetry

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2017年第7期36卷 102-109页

作者： liang jian ZHANG Jie MA Yi Dalian Maritime University Information Science and Technology College The First Institute of Oceanography State Oceanic Administration

A spatial resolution effect of remote sensing bathymetry is an important scientific problem. The in situ measured water depth data and images of Dongdao Island are used to study the effect of water depth inversion from different spatial resolution remote sensing images. The research experiments are divided into five groups including Quick Bird and World View-2 remote sensing images with their original spatial resolution（2.4/2.0 m）and four kinds of reducing spatial resolution（4, 8, 16 and 32 m）, and the water depth control and checking points are set up to carry out remote sensing water depth inversion. The experiment results indicate that the accuracy of the water depth remote sensing inversion increases first as the spatial resolution decreases from 2.4/2.0 to 4, 8 and16 m. And then the accuracy decreases along with the decreasing spatial resolution. When the spatial resolution of the image is 16 m, the inversion error is minimum. In this case, when the spatial resolution of the remote sensing image is 16 m, the mean relative errors（MRE） of Quick Bird and World View-2 bathymetry are 21.2% and 13.1%,compared with the maximum error are decreased by 14.7% and 2.9% respectively; the mean absolute errors（MAE） are 2.0 and 1.4 m, compared with the maximum are decreased by 1.0 and 0.5 m respectively. The results provide an important reference for the selection of remote sensing data in the study and application of the remote sensing bathymetry.

关键词： remote sensing spatial resolution water depth remote sensing inversion

Harmonic suppressed bandpass filter using composite right/left handed transmission line

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science C(Computers and Electronics) 2012年第7期13卷 552-558页

作者： jian-gang liang He-xiu XU Electromagnetic Field and Microwave Technique Missile InstituteAir Force Engineering UniversityShaanxi 713800China

A wideband composite right/left handed transmission line (CRLH TL) in conjunction with its corresponding equivalent circuit model is studied based on a cascaded complementary single split ring resonator (CCSSRR).The characterization is performed by theory analysis,circuit simulation,and full-wave electromagnetic (EM) *** negative refractive index (NRI) and backward wave propagation performance of the CRLH TL are *** application,a bandpass filter (BPF) with enhanced out-of-band selectivity and harmonic suppression operating at the wireless local area network (WLAN) band is designed,fabricated,and measured by combining the CRLH TL with a complementary electric inductive-capacitive resonator (CELC).Three CELC cells with wideband stopband performance in the conductor strip and ground plane,respectively,are utilized in terms of single negative *** design concept has been verified by the measurement data.

关键词： Composite right/left handed transmission line Cascaded complementary split single ring resonator Bandpass filter Complementary electric inductive-capacitive resonator (CELC) Negative permeability

Estimation of Road Friction Coefficient in Different Road Conditions Based on Vehicle Braking Dynamics

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2017年第4期30卷 982-990页

作者： You-Qun Zhao Hai-Qing Li fen Lin jian Wang Xue-Wu Ji College of Energy&Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China School of Automotive Engineering Shandong Jiaotong UniversityJinan 250023China State Key Laboratory of Automotive Safety and Energy Tsinghua UniversityBeijing 100084China

The accurate estimation of road friction coeffi- cient in the active safety control system has become increasingly prominent. Most previous studies on road friction estimation have only used vehicle longitudinal or lateral dynamics and often ignored the load transfer, which tends to cause inaccurate of the actual road friction coef- ficient. A novel method considering load transfer of front and rear axles is proposed to estimate road friction coef- ficient based on braking dynamic model of two-wheeled vehicle. Sliding mode control technique is used to build the ideal braking torque controller, which control target is to control the actual wheel slip ratio of front and rear wheels tracking the ideal wheel slip ratio. In order to eliminate the chattering problem of the sliding mode controller, integral switching surface is used to design the sliding mode sur- face. A second order linear extended state observer is designed to observe road friction coefficient based on wheel speed and braking torque of front and rear wheels. The proposed road friction coefficient estimation schemes are evaluated by simulation in ADAMS/Car. The results show that the estimated values can well agree with the actual values in different road conditions. The observer can estimate road friction coefficient exactly in real-time andresist external disturbance. The proposed research provides a novel method to estimate road friction coefficient with strong robustness and more accurate.

关键词： Road friction coefficient Real timeestimation External disturbance Different roadconditions

Effect of aluminum oxide on the compressive strength of pellets

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2014年第4期21卷 339-344页

作者： jian-liang Zhang Zhen-yang Wang Xiang-dong Xing Zheng-jian Liu School of Metallurgical and Ecological Engineering University of Science and Technology Beijing

Analytical-reagent-grade Al2O3 was added to magnetite ore during the process of pelletizing, and the methods of mercury intru-sion, scanning electron microscopy, and image processing were used to investigate the effect of Al2O3 on the compressive strength of the pellets. The results showed that, as the Al2O3 content increased, the compressive strength of the pellets increased slightly and then decreased gradually. When a small amount of Al2O3 was added to the pellets, the Al2O3 combined with fayalite （2FeO＆#183;SiO2） and the aluminosilicate （2FeO＆#183;2Al2O3＆#183;5SiO2） was generated, which releases some iron oxide and reduces the inhibition of fayalite to the solid phase of consolidation. When Al2O3 increased sequentially, high melting point of Al2O3 particles hinder the oxidation of Fe3O4 and the recrystallization of Fe2O3, making the internal porosity of the pellets increase, which leads to the decrease in compressive strength of the pellets.

关键词： magnetite ore pellets alumina compressive strength porosity microanalysis