检索结果-南通市图书馆

Synthesis of Various Types of Silver Nanoparticles Used as Physical Developing Nuclei in Photographic Science

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2003年第6期14卷 645-648页

作者： jun ping zhang Li Qi SHENG ping CHEN Technical Institute of Physics and Chemistry CASBeijing 100101

Ag nanoparticles used as physical developing nuclei in photographic science were prepared by reduction method. The as-formed Ag nanoparticle colloid was characterized by UV-Vis absorption spectrum, Atomic Force Microscopy(AFM) and Charge Coupled Device (CCD) technique. It is found that the source of Ag ions, the addition of surfactant and polymer, all have great influence on the size, topography and catalytic activity of Ag nanoparticles.

关键词： Ag nanoparticle AFM DTR.

Broadband channel measurement and analysis

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2006年第3期13卷 24-28页

作者： zhang Ming zhang Jian-hua JIANG jun zhang ping WU Yu-fei Wireless Technology Innovation Labs (WTI) Beijing University of Posts and Telecommunications Beijing 100876 China

An outdoor propagation measurement campaign for beyond 3G （B3G） as well as a wide-band indoor measurement campaign have been performed recently in Beijing, China, in which the sounding signals are transmitted by an one-antenna base station and received by a two-antenna mobile receiver operated at 3.49～3.51 GHz bandwidth. Different scenarios： stationary line-of-sight （LoS）, stationary non-LoS （NLoS） scenarios, and dynamic NLoS are deliberately chosen in a classic urban environment and office environment. The initial results are presented in this article. Parameters including vector channel impulse response, path loss, rays number, excess delay spread etc. are extracted, analyzed, and briefly reported here.

关键词： Broadband measurement Beyond 3G path loss,multipath delay rays number

Na^+ and Water Uptake in Relation to the Radial Reflection Coefficient of Root in Arrowleaf Saltbush Under Salt Stress

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Plant Biology 2007年第9期49卷 1334-1340页

作者： Xin-Fu Bai Jian-jun Zhu ping zhang Yan-Hua Wang Li-Qun Yang Lei zhang College of Life Sciences Ludong University Yantai 264025 China

The response of halophyte arrowleaf saltbush （Atriplex triangularis Willd） plants to a gradient of salt stress were investigated with hydroponically cultured seedlings. Under salt stress, both the Na^＋ uptake into root xylem and negative pressures in xylem vessels increased with the elevation of salinity （up to 500 mol/m^3） in the root environment. However, the increment in negative pressures in root xylem far from matches the decrease in the osmotic potential of the root bathing solutions, even when the osmotic potential of xylem sap is taken into consideration. The total water potential of xylem sap in arrowleaf saltbush roots was close to the osmotic potential of root bathing solutions when the salt stress was low, but a progressively increased gap between the water potential of xylem sap and the osmotic potential of root bathing solutions was observed when the salinity in the root environment was enhanced. The maximum gap was 1.4 MPa at a salinity level of 500 mol/m^3 without apparent dehydration of the tested plants. This discrepancy could not be explained with the current theories in plant physiology. The radial reflection coefficient of root in arrowleaf saltbush decreased with the enhanced salt stress was and accompanied by an increase in the Na^＋ uptake into xylem sap. However, the relative Na^＋ in xylem exudates based on the corresponding NaCl concentration in the root bathing solutions showed a tendency of decrease. The results showed that the reduction in the radial reflection coefficient of roots in the arrowleaf saltbush did not lead to a mass influx of NaCl into xylem when the radial reflection coefficient of the root was considerably small; and that arrowleaf saltbush could use small xylem pressures to counterbalance the salt stresses, either with the uptake of large amounts of salt, or with the development of xylem pressures dangerously negative. This strategy could be one of the mechanisms behind the high resistance of arrowleaf saltbush plants to

关键词： anti-osmosis arrowleaf saltbush (Atriplex triangularis Willd) radial reflection coefficient of root salt stress xylem pressure

A new multi-wavelength solar telescope: Optical and Near-infrared Solar Eruption Tracer (ONSET)

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12期13卷 1509-1517页

作者： Cheng Fang Peng-Fei Chen Zhen Li Ming-De Ding Yu Dai Xiao-Yu zhang Wei-jun Mao jun-ping zhang Ting Li Yong-jun Liang Hai-Tian Lu School of Astronomy&Space Science Nanjing University Key Laboratory of Modern Astronomy&Astrophysics Nanjing University Yunnan Astronomical Observatory/National Astronomical Observatories Chinese Academy of Sciences Nanjing Institute of Astronomical Optics and Technology Chinese Academy of Sciences

A new multi-wavelength solar telescope, the Optical and Near-infrared Solar Eruption Tracer （ONSET） of Nanjing University, has been constructed. It was fabricated at the Nanjing Institute of Astronomical Optics ＆ Technology, and the oper- ation is jointly administered with Yunnan Astronomical Observatory. ONSET is able to observe the Sun in three wavelength windows： He I 10830 A, Ha and white-light at 3600 A and 4250 A, which are selected in order to simultaneously record the dynam- ics of the corona, chromosphere and photosphere respectively. Full-disk or partial-disk solar images with a field of 10~ at three wavelengths can be obtained nearly simultane- ously. It is designed to trace solar eruptions with high spatial and temporal resolutions. This telescope was installed at a new solar observing site near Fuxian Lake in Yunnan Province, southwest China. The site is located at E102N24, with an altitude of 1722 m. The seeing is stable and has high quality. We give a brief description of the scientific objectives and the basic structure of ONSET. Some preliminary results are also pre- sented.

关键词： techniques: photometric -- Sun: observation -- Sun: telescope

Feature Matching via Topology-Aware Graph Interaction Model

在线全文

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2024年第1期11卷 113-130页

作者： Yifan Lu Jiayi Ma Xiaoguang Mei jun Huang Xiao-ping zhang the Electronic Information School Wuhan UniversityWuhan 430072China IEEE Tsinghua Berkeley Shenzhen Institute Shenzhen 518071China the Department of Electrical Computer and Biomedical EngineeringToronto Metropolitan UniversityToronto ON M5B 2K3Canada

Feature matching plays a key role in computer vision. However, due to the limitations of the descriptors, the putative matches are inevitably contaminated by massive *** paper attempts to tackle the outlier filtering problem from two aspects. First, a robust and efficient graph interaction model,is proposed, with the assumption that matches are correlated with each other rather than independently distributed. To this end, we construct a graph based on the local relationships of matches and formulate the outlier filtering task as a binary labeling energy minimization problem, where the pairwise term encodes the interaction between matches. We further show that this formulation can be solved globally by graph cut algorithm. Our new formulation always improves the performance of previous localitybased method without noticeable deterioration in processing time,adding a few milliseconds. Second, to construct a better graph structure, a robust and geometrically meaningful topology-aware relationship is developed to capture the topology relationship between matches. The two components in sum lead to topology interaction matching(TIM), an effective and efficient method for outlier filtering. Extensive experiments on several large and diverse datasets for multiple vision tasks including general feature matching, as well as relative pose estimation, homography and fundamental matrix estimation, loop-closure detection, and multi-modal image matching, demonstrate that our TIM is more competitive than current state-of-the-art methods, in terms of generality, efficiency, and effectiveness. The source code is publicly available at http://***/YifanLu2000/TIM.

关键词： Feature matching graph cut outlier filtering topology preserving

Effect of preparation methods on Pt/alumina catalysts for the hydrogen iodide catalytic decomposition

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2009年第1期20卷 102-105页

作者： Zhi Chao Wang Lai jun Wang ping zhang Song Zhe Chen Jing Ming Xu Jing Chen Laboratory 201 Institute of Nuclear and New Energy Technology Tsinghua University Beijing 102201 China

Three kinds of Pt/alumina catalysts were prepared by impregnation-hydrogen reduction, impregnation-hydrazine reduction and electroless plating methods. Their differences in the structures, specific areas and particle sizes were characterized by XRD, BET and TEM, respectively. Furthermore, their catalytic activities for the hydrogen iodide （HI） decomposition were evaluated in a fixed bed reactor. The results show that the catalyst 5%Pt/Al2O3 prepared by the electroless plating has the optimum catalytic properties for HI decomposition owing to the high dispersion of the platinum nano-particles （〈5 nm） on the alumina supports.

关键词： Hydrogen iodide Catalytic decomposition Pt/At2O3 Preparation methods

Propagation characteristics of parallel dark solitons in silicon-on-insulator waveguide

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 265-271页

作者： Zhen Liu Weiguo Jia Yang Wang Hongyu Wang Neimule Men-Ke jun-ping zhang School of Physical Science and Technology Inner Mongolia UniversityHohhot 010021 China

The propagation characteristic of two identical and parallel dark solitons in a silicon-on-insulator(SOI)waveguide is simulated numerically using the split-step Fourier *** parallel dark solitons imposed by the initial chirp are investigated mainly by changing their power,their relative time *** simulation shows that the time delay deforms the parallel dark soliton pulse,forming a bright-like soliton in the transmission process and making the transmission quality *** increasing the power of one dark soliton,the energy of the other dark soliton can be increased,and larger increase in a soliton’s power leads to larger increase in the energy of the *** the initial chirp is introduced into one of the dark solitons,higher energy consumption is *** particular,positive chirps resulting in pulse broadening width while negative chirps narrowing,with an obvious compression effect on the other dark ***,large negative chirps are found to have a profound impact on parallel and nonparallel dark solitons.

关键词： silicon-based optical waveguide dark soliton nonlinear effect interaction

Reinforcement of High Impact Polystyrene by Aramid Nanoparticle Fillers Prepared via an In situ Bottom-up Approach

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2024年第8期42卷 1167-1176页

作者： Xiang-jun Gong Zhi-ping Zhao Chang-Mei Sun Ying zhang Rong-jun Qu Ying Wang School of Chemistry and Materials Science Ludong UniversityYantai 264025China

In this work,aramid nanoparticles(ANPs)were prepared in dimethyl formamide(DMF)solution containing high impact polystyrene(HIPS)via a bottom-up *** electron microscopy(TEM)images showed that the obtained ANPs were evenly distributed in the HIPS matrix without any *** composition of the ANPs,i.e.,poly(p-phenyl-p-phenylenediamine)(PPTA),was confirmed by Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS)and X-ray diffractometer(XRD).The ANP/HIPS composites,obtained after ethanol precipitation,were added to neat HIPS as fillers to fabricate ANP/HIPS composite *** surface roughness and the glass transition temperature(T_g)of the sheets were characterized by atomic force microscope(AFM)and differential scanning calorimetry(DSC),*** with neat HIPS,the mechanical properties of the composite sheet were significantly improved,and the Young's modulus increased from 246.55 MPa to 2025.12 MPa,the tensile strength increased from 3.07 MPa to 29.76 MPa,and the toughness increased from 0.32 N/mm^2 to 3.92 N/mm^2,with an increase rate of 721%,869%and 1125%,***,the thermal stability of the composites improved with the increase in ANP content.

关键词： High impact polystyrene PPTA nanoparticle Reinforce Mechanical property

Effect of dark soliton on the spectral evolution of bright soliton in a silicon-on-insulator waveguide

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2020年第6期29卷 224-229页

作者： Zhen Liu Wei-Guo Jia Hong-Yu Wang Yang Wang Neimule Men-Ke jun-ping zhang School of Physical Science and Technology Inner Mongolia UniversityHohhot 010021China

The spectral evolution of bright soliton in a silicon-on-insulator optical waveguide is numerically simulated using the split-step Fourier *** power and input chirp of the dark soliton and the second-order dispersion are varied to investigate the effect of dark soliton on the spectrum of bright *** simulations prove that the dark soliton modifies the spectral shape of the bright ***,the variation in the power of dark soliton affects the splitting of bright ***,the chirped dark soliton can improve the spectral width and *** variation in the dispersion of dark soliton modifies the phase matching of the bright soliton and the dispersive wave emission,thereby affecting the spectral evolution.

关键词： spectral evolution silicon-based optical waveguide nonlinear effect bright and dark solitons phase matching