检索结果-南通市图书馆

Evolution of High-energy Electron Distribution in Pulsar Wind Nebulae

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

Research in Astronomy and Astrophysics 2024年第7期24卷 198-214页

作者： Yi-ming Liu Hou-Dun Zeng yu-Liang Xin si-ming Liu Yi Zhang Key Laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of SciencesNanjing 210023China School of Astronomy and Space Science University of Science and Technology of ChinaHefei 230026China School of Physical Science and Technology Southwest Jiaotong UniversityChengdu 610031China

In this paper,we analyze the spectral energy distributions of 17 powerful(with a spin-down luminosity greater than10~(35)erg s~(-1))young(with an age less than 15,000 yr)pulsar wind nebulae(PWNe)using a simple timein-dependent one-zone emission *** aim is to investigate correlations between model parameters and the ages of the corresponding PWNe,thereby revealing the evolution of high-energy electron distributions within *** findings are as follows:(1)The electron distributions in PWNe can be characterized by a double power-law with a super-exponential cutoff.(2)As PWNe evolve,the high-energy end of the electron distribution spectrum becomes harder with the index decreasing from approximately 3.5 to 2.5,while the low-energy end spectrum index remains constant near 1.5.(3)There is no apparent correlation between the break energy or cutoff energy and the age of PWNe.(4)The average magnetic field within PWNe decreases with age,leading to a positive correlation between the energy loss timescale of electrons at the break energy or the high-energy cutoff and the age of the PWN.(5)The total electron energy within PWNe remains constant near 2×10~(48)erg,while the total magnetic energy decreases with age.

关键词： radiation mechanisms non-thermal-ISM general-ISM supernova remnants-gamma-rays general

Catalytic Performance of Carbon Smoke over Ag-LSCF Composite Catalysts

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials Science) 2025年第1期 30-34页

作者：郭冠伦 HAN ming LU Shaomin yu Jing 鞠洪玲 Hubei Key Laboratory of Advanced Technology for Automotive Components & Hubei Collaborative Innovation Center for Automotive Components Technology Wuhan University of Technology College of Mechanical and Transportation Southwest Forestry University

To improve the catalytic performance of La0.6Sr0.4Co0.2Fe0.8O3（LSCF） towards carbon soot,we utilized the impregnation method to incorporate Ag into the prepared LSCF *** conducted a series of characterization tests and evaluated the soot catalytic activity of the composite catalyst by comparing it with the LaCoO3group,LaFeO3group,and catalyst-free *** results indicate that the Ag-LSCF composite catalyst exhibits the highest soot catalytic activity,with the characteristic temperature values of 376.3,431.1,and 473.9 ℃ at 10 %,50 %,and 90 % carbon soot conversion,*** values are 24.8,20.2,and 23.1 ℃ lower than those of the LSCF *** also shows that LSCF can improve the catalytic activity of soot after compounding with Ag,and reflects the necessity of using catalysts in soot combustion *** characterization and BET test show that Ag-LSCF has more abundant surface-adsorbed oxygen species,larger specific surface area and pore volume than LSCF,which also proves that Ag-LSCF has higher soot catalytic activity.

关键词：

Mechanically robust bamboo node and its hierarchically fibrous structural design

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

National Science Review 2023年第2期10卷 199-211页

作者： si-ming Chen si-Chao Zhang Huai-Ling Gao Quan Wang LiChuan Zhou Hao-yu Zhao Xin-yu Li ming Gong Xiao-Feng Pan Chen Cui Ze-yu Wang YongLiang Zhang HengAn Wu Shu-Hong yu Department of Chemistry Institute of Biomimetic Materials & Chemistry Anhui Engineering Laboratory of Biomimetic MaterialsDivision of Nanomaterials & Chemistry Hefei National Research Center for Physical Sciences at the Microscale Institute of Energy Hefei Comprehensive National Science Center University of Science and Technology of China CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsEngineering and Materials Science Experiment CenterUniversity of Science and Technology of China Institute of Innovative Materials (I2M) Department of Materials Science and EngineeringDepartment of Chemistry Southern University of Science and Technology

Although short bamboo nodes function in mechanical support and fluid exchange for bamboo survival,their structures are not fully understood compared to unidirectional fibrous ***,we identify the spatial heterostructure of the bamboo node via multiscale imaging strategies and investigate its me chanical properties by multimodal mechanical *** find three kinds of hierarchical fiber reinforcement schemes that originate from the bamboo node,including spatially tightened interlocking,triaxial interconnected scaffolding and isotropic *** reinforcement schemes,built on porous vascular bundles,microfibers and more-refined twist-aligned nanofibers,govern the structural stability of the bamboo via hierarchical *** addition,the spatial liquid transport associated with these multiscale fibers within the bamboo node is experimentally verified,which gives perceptible evidence for life-indispensable multidirectional fluid *** functional integration of mechanical reinforcement and liquid transport reflects the fact that the bamboo node has opted for elaborate structural optimization rather than ingredient *** study will advance our understanding of biological materials and provide insight into the design of fiber-reinforced structures and biomass utilization.

关键词： biological materials bamboo node hierarchical fiber structural reinforcement functional integration

Hydrogen Bond Cooperative Effect in single Cage Water Clusters

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Structural Chemistry 2020年第7期39卷 1213-1225页

作者： HU Xiao-Min yu yu-Tian CHEN si-yu LEI ming PU Min YANG Zuo-Yin Department of Physical Chemistry College of ChemistryBeijing University of Chemical TechnologyBeijing 100029China

In this paper,DFT method was used to study the relative stability of hydrogen bonding networks of numerous 512,51262 and 435663 water cluster *** we introduced an optimized six-digit definition to characterize diverse sub-grouped hydrogen bonds to consider the cooperative effect of the nearest and nextnearest neighbor water *** are totally 74 kinds of sub-grouped hydrogen bonds in cage hydrate clusters,and these energies can be obtained by iterative *** improvement effectively explains some regularity contained in hydrogen bonding cooperative *** general,donor or acceptor fragment sharing identical value of three independent digits usually performs poor cooperative effect,indicating that the existence of those same-digital-array fragments is the necessary condition to judge poor cooperative *** versa,the existence of different-digital-array is also the necessary condition to judge strong cooperative effect.

关键词： sub-grouped hydrogen bond cooperative effect water cluster nearest neighbor next-nearest neighbor

A novel dandelion-based bionic proppant and its transportation mechanism in different types of fractures

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2024年第4期21卷 2583-2599页

作者： Jun Li ming-Yi Wu Xu Han si-yuan He Ze-yu Lin State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu610500SichuanChina sichuan Particles Energy and Technology Co. LtdChengdu610599SichuanChina Chongqing Industry Polytechnic College Chongqing401120China Petroleum Systems Engineering Faculty of Engineering and Applied ScienceUniversity of ReginaReginaSaskatchewanS4S 0A2Canada

Low-permeability reservoirs are generally characterized by low porosity and low *** high production using the traditional method is technologically challenging because it yields a low reservoir recovery *** recent years,hydraulic fracturing technology is widely applied for efficiently exploiting and developing low-permeability reservoirs using a low-viscosity fluid as a fracturing ***,the transportation of the proppant is inefficient in the low-viscosity fluid,and the proppant has a low piling-up height in fracture *** key challenges restrict the fluid(natural gas or oil)flow in fracture channels and their functional flow areas,reducing the profits of hydrocarbon *** study aimed to explore and develop a novel dandelion-bionic proppant by modifying the surface of the proppant and the *** structure was similar to that of dandelion seeds,and it had high transport and stacking efficiency in low-viscosity liquids compared with the traditional ***,the transportation efficiency of this newly developed proppant was investigated experimentally using six different types of fracture models(tortuous fracture model,rough fracture model,narrow fracture model,complex fracture model,large-scale single fracture model,and small-scale single fracture model).Experimental results indicated that,compared with the traditional proppant,the transportation efficiency and the packing area of the dandelion-based bionic proppant significantly improved in tap water or low-viscosity *** with the traditional proppant,the dandelionbased bionic proppant had 0.1-4 times longer transportation length,0.3-5 times higher piling-up height,and 2-10 times larger placement *** newly developed proppant also had some other extraordinary *** tortuosity of the fracture did not influence the transportation of the novel *** proppant could easily enter the branch fracture and narrow fracture with a hig

关键词： Dandelion-based bionic proppant Low-viscosity fracturing fluid Unconventional reservoir Volumetric fracturing stimulation

Analysis of echo signal modulation characteristic parameters on aerial and space targets

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10期28卷 146-154页

作者： si Chen Hai-yang Zhang Chang-ming Zhao yu Fan Hong Chen Lin Wang School of Optics and Photonics Beijing Institute of TechnologyBeijing100081China Key Laboratory of Electro-Optical Countermeasures Test&Evaluation Technology Unit 63891 of the Chinese People's Liberation ArmyHenan461002China Key Laboratory of Optical Radiation Beijing Institute of Environmental CharacteristicsBeijing100854China

Based on the scattering characteristic,the comparison of RCS(radar cross-section)at different positions of a target in the same direction of incidence can be obtained first by extruding or deleting part of the entity.A simulation method of aerial&space targets echo characteristics(A&STEC)is proposed that is universal to aerial and space *** utilize a fixed-wing UAV(unmanned aerial vehicle)and typical missiles in *** echo signal modulation characteristic parameters are calculated theoretically by the atmospheric attenuation model,the finite element method and a MUMPS *** verification simulations show that this method can analyze the influence of the target shape,incident direction,detection position and detection frequency on echo waveform,intensity and energy *** results show that the profile of echo waveform can invert the general shape of the *** relationship between time and intensity can determine whether the target is moving towards or away from the detector in *** conclusions can provide a reference for the ballistic missile target tracking and the defense against UVA intrusion in theory.

关键词： Echo signal modulation characteristic parameters simple targets The fixed-wing UVA Missiles Scattering characteristics

Synthesis of MOF-derived nitrogen-doped carbon microtubules via template self-consumption

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2022年第8期41卷 2582-2587页

作者： Duo Wang Ze-yu Zhao Ping Wang si-Miao Wang ming Feng Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education Jilin Normal UniversityChangchun130103China

Herein,by optimizing nano-ZnO template,N-doped hollow carbon microtubules with controllable thickness are synthesized deriving from ZnO@zeolitic lmidazolate framework(ZIF-8)nanorod by template self-consumption method,and a superior structure with graphene-like layers of an average length of 5μm and diameter of 200 nm are proposed to be used as the cathode carries for Li-S *** electrochemical testing,we found that the prepared hollow carbon microtubules have higher discharge capacity and better rate performance than the ZIF-8 derived carbon,showing potential application *** work provides a feasible way for the preparation of monodisperse graphene-like hollow materials.

关键词： materials. template carbon

在线全文

学校读者我要写书评

暂无评论

自激式电感耦合等离子体光源设计及光谱分析

光谱学与光谱分析 2025年第1期45卷 66-71页

作者：卢思贤龙开红詹陈锐李明北方工业大学电气与控制工程学院北京100144 益阳职业技术学院电子与信息工程学院湖南益阳413055

电感耦合等离子体(ICP)光谱仪是一种应用范围很广的元素分析仪,主要用于元素定性与定量的分析。ICP光源是光谱仪的核心部件,它在光谱仪中扮演着至关重要的角色。目前主流的ICP光源有两种:自激式和他激式,各自具有优缺点。他激式光源电... 详细信息

电感耦合等离子体(ICP)光谱仪是一种应用范围很广的元素分析仪,主要用于元素定性与定量的分析。ICP光源是光谱仪的核心部件,它在光谱仪中扮演着至关重要的角色。目前主流的ICP光源有两种:自激式和他激式,各自具有优缺点。他激式光源电路复杂、体积庞大、阻抗匹配速度较慢、最大输出功率有限。设计了一种基于镀金工艺的高功率MOSFET和变频实现阻抗匹配的自激式ICP光源,该光源采用射频放大和阻抗匹配一体化的设计,把从负载线圈采样的频率信号f_(1)以及功率放大电路放大后的频率相位f_(0)进行相位比较,再根据两者相位差的变化,进而控制频率的变化,实现阻抗匹配;设计上采用了镀金工艺的金属化硅N通道型高功率的MOSFET实现功率放大,具有更大的功率密度、更小的体积,最大输出功率超过2400 W。对研制的ICP光源进行了电学静态测试,给出了鉴相器、压控振荡器以及功率的输出特性,验证了各电路在相应工作状态下的性能表现;同时结合光谱仪进行了包含Ba、Na和Li元素标准溶液的测试,获得了目标元素的光谱信号;另外,对获得的光谱信号进行了处理,使用了基于EEMD特征增强的方法对目标元素光谱信号进行有效增强,信号的线性决定系数(R^(2))从0.97降至0.99,相对标准偏差(RSD)从6.47%降至1.07%,增强了信号的准确性和可用性。本文所研制的自激式ICP光源,通过射频放大和阻抗匹配一体化设计缩小了体积,变频技术使阻抗匹配速度从毫秒级提升到纳秒级,镀金工艺的MOSFET技术使最大输出功率从原来的1800 W增加到2400 W,为ICP光源的进一步优化和应用奠定了基础,具有重要的科学研究和工程实践意义。

关键词：自激式ICP光源阻抗匹配光谱信号 EEMD算法

DAO媒介:驱动未来社会算法化与自组织的元媒介

在线全文

学校读者我要写书评

暂无评论

新疆师范大学学报（哲学社会科学版） 2025年第1期46卷 132-141页

作者：喻国明苏健威北京师范大学新闻传播学院北京师范大学传播创新与未来媒体实验平台北京100875

DAO媒介是以区块链算法等技术为基础,支持数字社群协同自治的媒介,具有区块链、智能合约与投票等功能特性和要素确权、技术信任、规则构架以及场景聚合等价值禀赋。对于数字生态显露的各种问题,“算法化”是重构数字生态、降解社会系统... 详细信息

DAO媒介是以区块链算法等技术为基础,支持数字社群协同自治的媒介,具有区块链、智能合约与投票等功能特性和要素确权、技术信任、规则构架以及场景聚合等价值禀赋。对于数字生态显露的各种问题,“算法化”是重构数字生态、降解社会系统复杂性的关键机制,DAO媒介是支撑“自组织式”算法化的元媒介。DAO媒介与数字文明时代喷发的微粒个体、微资源、微价值、微需求、微场景等相匹配,能够深度匹配人的个性与自我,形成有效的趣缘连接,进而极大地释放数字文明的生产力。DAO媒介将深刻影响社会系统的构造,将微粒个体与相关社会要素“包裹”为闭环子系统,支持其准开放的系统边界、有效的异质性整合、可持续的规则重构、子系统与父级系统的持续分化和快速进化,等等。在数字文明时代,DAO媒介将使“重新部落化”的“地球村”变为现实,其驱动构筑的DAO社会将更加多元、更加富有创造力,不断拓展人类群体实践的自由度,使人类在高度异质性聚合基础上更加和谐有序地整合协同。

关键词： DAO 数字媒介算法自组织社会系统