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Cosmic-Ray Positrons Produced by Pulsar Winds from Mature Gamma-Ray Pulsars

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Chinese Physics Letters 2001年第5期18卷 701-704页

作者： ZHANG Li k.s.cheng MEI Dong-cheng Department of Physics Yunnan UniversityKunming 650091 Department of Physics University of Hong KongPokfulam RoadHongKong Yunnan Observatory Chinese Academy of SciencesKunming 650011

In the frame of theγ-ray pulsar outer gap model,e^(±)pairs in the pulsar magnetosphere are produced by the cascade of e^(±)pairs through synchrotron radiation of the return current from the outer *** pairs are accelerated mono-energetically to relativistic energies in the pulsar wind driven by low-frequency electromagnetic *** Monte Carlo simulations,we generate a sample of the matureγ-ray pulsars in our Galaxy and calculate the positron production rate from these *** a simple leaky box model,we calculate the ratio of cosmic-ray positron to total *** result indicates that the pulsar contribution to the cosmic ray positron peaks at about 40 GeV and the observed e^(+)/(e^(-)+e^(+))ratio can be explained by this model.

关键词： cosmic outer return

On the Light Curve and spectra of X-Rays and Gamma-Rays from the Crab Pulsar

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Chinese Physics Letters 2000年第7期17卷 544-546页

作者： ZHANG Li k.s.cheng MEI Dong-cheng Yunnan Astrophysics Center Yunnan UniversityKunming 650091 Department of Physics University of Hong KongPokfulam RoadHong Kong

We use a three-dimensional pulsar magnetosphere model to study the light curve and spectra of x-rays and gamma-rays from the Crab pulsar. In this model, the vertical size of the outer gap is first determined by a self-consistent model in which the outer gap is limited by pair production from collisions of thermal photons produced by polar cap heating of backflow outer gap current and curvature photons emitted by gap accelerated charged particles. The transverse size of the outer gap is determined by local pair production conditions. In principle, there are two topologically disconnected outer gaps present in the magnetosphere of a pulsar, and both incoming and outgoing particle flows are allowed. However, double-peak light curves with strong bridges are most common, Making use of the three-dimensional structure of the outer gap and its local properties, we compare the results of our model with the light curve and phase-resolved spectra of the Crab pulsar.

关键词： particles conditions outer

Gamma-Ray Bursts: Afterglows and Central Engines

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Chinese Journal of Astronomy and Astrophysics 2001年第1期1卷 1-20页

作者： k.s.cheng T.Lu DepartmentofPhysics UniversityofHongKongPokfulamRoadHongKong DepartmentofAstronomy NanjingUniversit

Gamma-ray bursts (GRBs) are the most intense transient gamma-ray events in the sky; this, together with the strong evidence (the isotropic and inhomogeneous distribution of GRBs detected by BAsTE) that they are located at cosmological distances, makes them the most energetic events ever known. For example, the observed radiation energies of some GRBs are equivalent to the total convertion into radiation of the mass energy of more than one solar mass. This is thousand times stronger than the energy of a supernova explosion. some unconventional energy mechanism and extremely high conversion efficiency for these mysterious events are required. The discovery of host galaxies and association with supernovae at cosmological distances by the recently launched satellite of BepposAX and ground based radio and optical telescopes in GRB afterglow provides further support to the cosmological origin of GRBs and put strong constraints on their central engine. It is the aim of this article to review the possible central engines, energy mechanisms, dynamical and spectral evolution of GRBs, especially focusing on the afterglows in multi-wavebands.

关键词： gamma-rays: bursts - shock waves - IsM: jets and outflows- radiation mechanisms: non-thermal

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Broad Band spectra of Pulsars and PWNe

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Broad Band Spectra of Pulsars and PWNe

中国天文学会2004年学术年会

作者： k.s.cheng Department of Physics University Hong kang

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多级薄层过滤机的洗涤

流体机械 1984年第5期 56-62页

作者： k.s.cheng ,F.M.Tiller ,Alex Bagdasarian ,时云天津化工修配厂

洗涤是固液分离过程中的一个重要部分。通过洗涤可以回收积存在滤渣内的有价值液体。另一方面,由于用洗涤水代替了母液,在滤渣中可溶质的浓度可以降低。在过滤过程中用清净的洗涤液通过过滤机中的滤渣,洗涤就能够顺利完成。由于母液被... 详细信息

洗涤是固液分离过程中的一个重要部分。通过洗涤可以回收积存在滤渣内的有价值液体。另一方面,由于用洗涤水代替了母液,在滤渣中可溶质的浓度可以降低。在过滤过程中用清净的洗涤液通过过滤机中的滤渣,洗涤就能够顺利完成。由于母液被洗涤液置换出来,所以在开始时效率是高的,

关键词：过滤速率滤渣料浆固体浓度过滤机洗涤液薄层地层

The growth of central black holes associated with ionization instability in quasars

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The growth of central black holes associated with ionization...

乌鲁木齐天文站25m天线18cm脉冲星脉冲到达时间观测系统

黑洞物理研讨会

作者： Y. Lu National Astronomical Observatories, Chinese Academy of sciences, Beijing, China, 100012 k.s.cheng Department of Physics, The University of Hong kong, Hong kong, China s.N.Zhang Physics Department and Center for Astrophysics, Tsinghua University, Beijing, 100084, China

A possible accretion model associated with the ionization instability of quasar disks is proposed to address the growth of the central black hole harbored in the host galaxy. The evolution of quasars in cosmic time is assumed to change from a highly active state to a quiescent state triggered by the s-shaped ionization instability of the quasar accretion disk. Our model demonstrates that a seed BH (- 2 ×106M⊙) similar to those found in spiral galaxies today is needed to produce a BH with a final mass (- 2 ×106M⊙).

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天体物理学报 1999年第4期19卷 445-450页

作者：张晋张晋吴鑫基吴鑫基王娜王娜王娜王娜艾力.玉艾力.玉 k.s.cheng 中国科学院乌鲁木齐天文站乌鲁木齐830011 中国科学院国家天文观测中心北京100012 北京大学地球物理系北京100871 中国科学院-北京大学联合北京天体物理中心北京100875 香港大学物理系香港

脉冲星脉冲到达时间观测系统建立在２５ｍ射电天线的１８ｃｍ波段上，消色散采用了２ｘ１２８ｘ２．５ＭＨｚ多通过滤波器和数字化器，数据采集系统由ＰＣ机完成．１９９９年５月至６月间建立了基于常温接收机的到达时间观测系统．观测... 详细信息

脉冲星脉冲到达时间观测系统建立在２５ｍ射电天线的１８ｃｍ波段上，消色散采用了２ｘ１２８ｘ２．５ＭＨｚ多通过滤波器和数字化器，数据采集系统由ＰＣ机完成．１９９９年５月至６月间建立了基于常温接收机的到达时间观测系统．观测到的最弱源的平均流量密度为４ｍＪｙ．

关键词：脉冲星观测射电望远镜天文站

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A mild, configurable, flexible CoNi-LDH（v）/Zn battery based on H-vacancy-induced reversible Zn2+ intercalation

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Journal of Energy Chemistry 2025年第1期100卷 498-508页

作者： Xinyue cheng Dingsheng Wu Hao Gao Qingqing Wang Pengfei Lv sam s.Yoon Qufu Wei key Laboratory of Eco-textiles Ministry of Education Jiangnan University school of Mechanical Engineering Korea University

Flexible Zn-based batteries have attracted increasing research interest as essential components of wearable energy storage ***,the advancement of flexible aqueous Zn-based batteries based on Co-Ni layered double hydroxide （CoNi-LDH） as the cathode material is hampered by their poor cycling stability and the corrosiveness of alkaline ***,CoNi-LDH nanosheets enriched with H vacancies (CoNi-LDH（v）) were constructed on a flexible carbon cloth （CC） substrate via electrochemical deposition and *** Zn-based battery comprising CoNi-LDH（v）@CC as the cathode exhibited highly reversible conversion reactions and stable operation in 3 M ZnsO4electrolyte （pH=4）.The battery delivered an excellent specific capacity (225 mA h g-1,0.26 mA h cm-2),acceptable cycling stability（53.9%,900 cycles）,and high discharging *** abundant H vacancies served as active sites for the reversible intercalation of Zn2+and the extravasation of NO3-generated channels and space for Zn2+transport and storage,together enabling an excellent Zn2+storage ***,a sandwich-structured solid-state CoNi-LDH（v）@CC//Zn@CC battery was fabricated and was found to exhibit a noteworthy electrochemical performance and mechanical *** a proof of concept,the unencapsulated battery powered a digital watch under various deformation conditions and operated stably for 80 ***,the flexible battery displayed outstanding customizability,maintaining an open-circuit voltage of 1.42 V even after being cut *** proposed engineering strategy contributes to the realization of textiles with truly wearable energy-storage devices.

关键词： CoNi/Zn battery H vacancies Mild aqueous electrolyte Tailorable battery Wearable energy storage device

云南稻种资源的综合研究与利用 Ⅶ关于西、南亚稻种类型的讨论

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北京农业大学学报 1985年第3期 239-248页

作者：程侃声黄乃威罗军卢义宣刘光荣王象坤云南农科院北京农业大学

在亚洲栽培稻的分类上,许多作者都提出过'中间型'的问题。我们则提出应只分籼粳两亚种,在亚种之下设生态群——生态型的建议。我们就形态特征对南亚和西亚稻种的分类与 Glaszmann 依据同工酶的分类取得基本一致的结果。其中分布在尼泊... 详细信息

在亚洲栽培稻的分类上,许多作者都提出过'中间型'的问题。我们则提出应只分籼粳两亚种,在亚种之下设生态群——生态型的建议。我们就形态特征对南亚和西亚稻种的分类与 Glaszmann 依据同工酶的分类取得基本一致的结果。其中分布在尼泊尔以西的巴基斯坦、伊朗和阿富汗的细长粒粳稻,我们称之为'镰刀谷'是一种特殊生态型,曾被误分为籼稻,而分布在尼泊尔以东从阿萨姆直到云南的'镰刀谷'也多为粳稻,但无稃毛,可能为另一粳稻系统。'镰刀谷'中不少优质米和香米品种。本研究揭示了在南亚和西亚地带也存在着不少有用的粳稻资源,并确有一些偏籼、偏粳但不是真正'中间型'的品种,这无疑将在扩大粳稻育种的种质来源和进一步研究稻种的起源和分化展开一个新的视野。

关键词：稻种资源阿富汗伊朗粳稻水稻镰刀谷南亚云南