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Test mass charging simulation of ASTROD I due to solar energetic particles at 0.5 AU

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Science china(Physics,Mechanics & Astronomy) 2010年第6期53卷 1139-1143页

作者： bao gang & LIU Lei purple mountain observatory,chinese academy of sciences,nanjing 210008,china purple mountain observatory Chinese Academy of Sciences Nanjing China

Maintaining the geodesic motion of the test mass is vital to ASTROD I space mission. However,the electrostatic charging of the test mass due to cosmic rays and solar energetic particles will result in Coulomb and Lorentz forces and consequently influence the test mass motions. To estimate the size of these effects,a credible simulation of test mass charging processes is critically required. Using the GEANT4 software toolkit,we have modeled the charging processes and predict how the ASTROD I test mass will charge positively at a rate of 217370 e + /s,due to solar energetic particles(SEPs) at～0.5 AU caused by the largest SEPs event on 29,September,1989. In addition to Monte Carlo uncertainty,an error of ±30% in the net charging rates was added to account for uncertainties in the spectra,physics and geometry models.

关键词： charging simulation ASTROD I GEANT4 solar energetic particles

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彗木相撞中的波动

天文学报 2003年第4期44卷 337-341页

作者：陈道汉包纲中国科学院紫金山天文台南京210008 中国科学院国家天文台北京100012

1994年7月18日至24日期间,彗星苏梅克-列维9(SL-9)的超过20块碎片与木星发生了相撞.哈勃空间望远镜(HST)拍摄到的图像揭示了木星大气对撞击的动力学响应.具有重要意义的是观测到5个撞击点周围的圆环,它们以450米/秒的常速度向外运动.环... 详细信息

1994年7月18日至24日期间,彗星苏梅克-列维9(SL-9)的超过20块碎片与木星发生了相撞.哈勃空间望远镜(HST)拍摄到的图像揭示了木星大气对撞击的动力学响应.具有重要意义的是观测到5个撞击点周围的圆环,它们以450米/秒的常速度向外运动.环的圆形性表明它们是波.因为对于不同大小的撞击,波速是常量,可以推断出传播速度与爆炸能量无关.这意味着这些波动是线性波. 评述现行理论所使用的3类候选波,亦即惯性引力波、声波和地震波,介绍的重点是前面两种.

关键词：波动行星木星彗星

A Correlation-Based Stochastic Model for Massive MIMO Channel

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china Communications 2024年第1期21卷 175-187页

作者： Yang Liu gang Li Chengxiang Wang National Mobile Communications Research Laboratory School of Information Science and EngineeringSoutheast UniversityNanjing 211189China School of Internet of Things Engineering Jiangnan UniversityWuxi 214122China Pervasive Communication Research Center Purple Mountain LaboratoriesNanjing 211111China

In this paper,the channel impulse response matrix(CIRM)can be expressed as a sum of couplings between the steering vectors at the base station(BS)and the eigenbases at the mobile station(MS).Nakagami distribution was used to describe the fading of the coupling between the steering vectors and the *** measurements were carried out to evaluate the performance of this proposed ***,the physical implications of this model were illustrated and the capacities are *** addition,the azimuthal power spectrum(APS)of several models was ***,the channel hardening effect was simulated and *** showed that the proposed model provides a better fit to the measured results than the other CBSM,i.e.,Weichselberger ***,the proposed model can provide better tradeoff between accuracy and complexity in channel *** CIRM model can be used for massive MIMO design in the future communication system design.

关键词： CBSM channel capacity channel hardening channel modeling massive MIMO

Tillage Pedogenesis of purple Soils in Southwestern china

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Journal of mountain Science 2009年第2期6卷 205-210页

作者： HE Xiubin bao Yuhai NAN Hongwei XIONG Donghong WANG Li LIU Yanfeng ZHAO Jingbo Institute of mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041 China Graduate School of the chinese academy of sciences Beijing 100049 China Shaanxi Normal University Xi'an 710062 China

Land cultivation and tillage process, and their consequent impacts on soil erosion, have been criticized as the main cause of degradation of land or soil quality. However, purple soils, classified as Regosols in FAO Taxonomy or Entisols in USDA Taxonomy, are formed from purple rocks of the Trias- Cretaceous system, have been developed or at least accelerated the development due to continual tillage operation, especially digging and ridging. The present study took micromorphological investigation on the sedimentary rocks and the soils under different operations of tillage. Results show that the purple rock of Feixiangguan Formation of the Trias system （Tlf） is the easiest to physical weathering and the most fertile soil material enriched in nutrients, and it has been, therefore, mostly cultivated and intensively tilled around the year. It has the fastest soil formation rate. Soil formation rate in the cropland with conventional tillage is higher than that in the forestiand and the grassland. It implies that the artificial brokenness and tillage disturbance play a great role in physical weathering and initiating soil formation processes.

关键词： Tillage impact pedogenesis purple soil micromorphology southwestern china

Cosmology-Independent Photon Mass Limits from Localized Fast Radio Bursts by Using Artificial Neural Networks

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chinese Physics Letters 2024年第5期41卷 177-183页

作者：冉景遇王宝魏俊杰 purple mountain observatory Chinese Academy of SciencesNanjing 210023China School of Astronomy and Space sciences University of Science and Technology of ChinaHefei 230026China

A hypothetical photon mass m_(γ) can produce a frequency-dependent vacuum dispersion of light, which leads to an additional time delay between photons with different frequencies when they propagate through a fixed distance. The dispersion measure and redshift measurements of fast radio bursts(FRBs) have been widely used to constrain the rest mass of the photon. However, all current studies analyzed the effect of the frequency-dependent dispersion for massive photons in the standard ΛCDM cosmological context. In order to alleviate the circularity problem induced by the presumption of a specific cosmological model based on the fundamental postulate of the masslessness of photons, here we employ a new model-independent smoothing technique, artificial neural network(ANN), to reconstruct the Hubble parameter H(z) function from 34 cosmic-chronometer *** combining observations of 32 well-localized FRBs and the H(z) function reconstructed by ANN, we obtain an upper limit of m_(γ) ≤ 3.5 × 10^(-51)kg, or equivalently m_(γ) ≤ 2.0 × 10^(-15)eV/c^(2)(m_(γ) ≤ 6.5 × 10^(-51)kg, or equivalently m_(γ) ≤ 3.6 × 10^(-15)eV/c_(2)) at the 1σ(2σ) confidence level. This is the first cosmology-independent photon mass limit derived from extragalactic sources.

关键词： dispersion limit Independent

Erosion and Sediment Production in Small Watershed in purple Hilly Areas and Prevention Techniques

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Wuhan University Journal of Natural sciences 2003年第3B期8卷 1041-1046页

作者： Zhang bao-hua, He Yu-rong, Zhou Hong-yi, Zhu BoInstitute of mountain Hazards and Environment, chinese academy of sciences, Chengdu 610041, Sichuan, china Department of Geography, Liaocheng University, Liaocheng 252059, Shandong, china Institute of mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041 SichuanChina Department of Geography Liaocheng UniversityLiaocheng 252059 Shandong China Institute of mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041 SichuanChina

purple Soil distributes extensively and mainly in china. Because of abundant easily weatherable parent rocks/ materials and unstable soil structure, and also influenced by parent materials, usage systems, and slope gradients, erosion and sediment production of purple soils are very severe with main fashions of water erosion and gravitational erosion. Basing on observed data in small watersheds, rainfall erosivity, vegetation coverage, previous soil water content, flow and relating factors such as climate, topograph of small watershed, land usage, and soil kinds are all the influence factors of erosion and erodibility of purple soil as well as sediment production and transport in small watershed of purple hilly areas. The effective technological countermeasures of ecosystem restoration, agricultural tillage for water conservation and erosion prevention, agriculture project, and soil changing for fertility and anti-erosion were provided.

关键词： purple soil characteristics of erosion and sediment production) influence factors prevention techniques

紫金山天文台15厘米折光镜的测光性能探讨——非消色差波段测光中调焦的作用

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天文学报 1963年第2期 150-167页

作者：姚保安中国科学院紫金山天文台

本文叙述根据较差测量法,试用柯达103a—D+GG11、103a—O+GG13及103a—O+UG2组合,对本台口径15厘米折光镜进行 U、B、V 系统照相测光.结果表明,前两种组合的有效波长约为5610及4440,比 B、V 系统的长.焦点照相结果,星等与标准值有系统差... 详细信息

本文叙述根据较差测量法,试用柯达103a—D+GG11、103a—O+GG13及103a—O+UG2组合,对本台口径15厘米折光镜进行 U、B、V 系统照相测光.结果表明,前两种组合的有效波长约为5610及4440,比 B、V 系统的长.焦点照相结果,星等与标准值有系统差.这具望远镜消色差在蓝紫波段,当在其他波段测光时,焦距调节对星等测定极为敏感.但存在一个焦距调节范围,在此范围内照相,可以消去系统差.这个范围对三种组合都不同.103a—D+GG11,约在该组合的焦点以外2毫米处,可变范围约±0.2毫米;对103a—O+GG13,从该组合焦外1.5厘米到星象显著变大的焦外;对103a—O+UG2,从该组合焦外约1毫米到星象显著变大的焦外.为校验上述结果,拍摄了疏散星团M45, M45,NGC752和IC4665.用103a—D+GG11还观测了红化 O 星协 CygⅥ.在我们使用这架望远镜进行照相测光工作所要求的精度下,这个方法是可以应用的.我们使用萨尔托累光瞳光度计(Sartorius Iris Photometer)测量底片,讨论了测量方法及误差.此外,还考察了导星不好的初步后果,在我们所要求的精度上没有发现显著影响.

关键词：焦距露光底片星等疏散星团银河星团消色差侧光边缘光光瞳滤光片波段测光

Trigger mechanism of loess-mudstone landslides inferred from ring shear tests and numerical simulation

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Journal of mountain Science 2021年第9期18卷 2412-2426页

作者： WANG Xin-gang LIAN bao-qin Liu Kai Luo Li State Key Laboratory of Continental Dynamics Department of GeologyNorthwest UniversityXi'an 710069China

Whereas loess-mudstone landslides are widely distributed and frequently occurred at the loess Plateau,this type of landslides is hard to detect due to its particularity,and easily generates serious *** clarify the shear characteristics and formation mechanism of loess-mudstone landslides,field investigations,ring shear tests and numerical simulation analyses were performed on the loess specimens collected from the Dingjiagou landslide in Yan’an city,*** test results showed that both the peak strength and residual strength of slip zone soils have a decreasing tendency with moisture content,while the increasing of normal stress caused an increase in the shear *** phenomena indicate that the rise in the moisture content induced by precipitation or the decreasing of normal stress due to excavation activities would result in the weakening of slip zone *** simulations of the evolution process of slope failure using the finite element method were conducted based on the Mohr–Coulomb *** was found that the heavy precipitation played a more important role in the slope instability compared with the *** addition,the field investigation showed that loess soils with well-developed cracks and underlying mudstone soils provide material base for the formation of loess-mudstone ***,the formation mechanism of this type of landslides was divided into three stages,namely,the local deformation stage,the penetration stage,the creeping-sliding *** study may provide a basis for understanding the sliding process of loess-mudstone landslides,as well as guidelines for the prevention and mitigation of loess-mudstone landslides.

关键词： Loess-mudstone landslides Slip zone soil Ring shear tests Numerical simulation Formation mechanism

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四分点集中阻尼弦系统本征解的性质

科学技术与工程 2024年第20期24卷 8403-8408页

作者：郑罡王保權王梦丽张永顺曾广榕重庆交通大学省部共建山区桥梁及隧道工程国家重点实验室重庆400074

带有集中阻尼的张紧弦系统在力学模型上属于混杂动力学系统,通常采用近似方法求解本征值以满足工程应用需求,为进一步明确该类系统的振动特性,有必要从解析角度探讨其本征问题。针对四分点集中阻尼弦系统,推导并化简其频率方程的代数形... 详细信息

带有集中阻尼的张紧弦系统在力学模型上属于混杂动力学系统,通常采用近似方法求解本征值以满足工程应用需求,为进一步明确该类系统的振动特性,有必要从解析角度探讨其本征问题。针对四分点集中阻尼弦系统,推导并化简其频率方程的代数形式,求得代数方程的解,经过换元逆过程,获得原频率方程的所有闭合解。发现闭合解共存在3组,其中两组互为共轭,根据代数基本定理讨论闭合解的结构。结果表明:系统存在两种相同的运动特征,其单位时间对数衰减率相同,频率互为相反数;系统中3个解支对应的单位时间对数衰减率和频率,总是随着阶次的增加而呈周期循环的;在同一解支下的各单值分支也呈周期性循环,即随着阶次的增加,其对应频率增加4π的整数倍,而单位时间对数衰减率保持不变。综上可知,集中阻尼弦系统的运动特性总是随着阶次的增加而重复变化,且变化周期与阻尼安装位置相关。

关键词：张紧弦本征值集中阻尼本征函数非经典线性系统