检索结果-南通市图书馆

Current-carrying tribological behavior of C/Cu contact pairs in extreme temperature and humidity environments for railway catenary systems

引用

Science China(Technological Sciences) 2024年第8期67卷 2537-2548页

作者： SHEN MingXue ji DeHui HU Qiang XIAO Li LI QiuPing State Key Laboratory of Performance Monitoring and Protecting of Rail Transit Infrastructure East China Jiaotong UniversityNanchang 330013China School of Materials Science and Engineering East China Jiaotong UniversityNanchang 330013China Institute of Applied Physics Jiangxi Academy of SciencesNanchang 330095China

Many current-carrying contact pairs, such as those found in pantograph-catenary systems, operate in open environments and are susceptible to significant external interference from temperature and humidity variations. This study investigated the evolution of the friction coefficient and contact resistance of C/Cu contact pairs under alternating temperature, humidity, and current conditions. Through experimentation, the wear rate and microtopography of the worn surface were analyzed under various constant parameters. Subsequently, the differences in tribological behavior and current-carrying characteristics of the contact pairs under these three parameters were explored. The results revealed that the decrease in temperature resulted in a significant increase in the friction coefficient of the contact pairs, carbon wear, and copper surface roughness. Additionally, the surface oxidation rate was lower at lower temperatures. Moreover, contact resistance did not consistently increase with decreasing temperature, owing to the combined action of the contact area and the oxide film. Compared with temperature, humidity fluctuations at room temperature exerted less influence on the friction coefficient and contact resistance of the contact pairs. Dry environments rendered carbon materials vulnerable to oxidation and cracking, while excessive humidity fostered abrasive wear and arcing. High-current conditions generally degraded the tribological properties of C/Cu contacts. In the absence of current, the friction coefficient was extremely high, and the copper transfer was high. Under excessive current, copper was susceptible to plowing by carbon micro-bumps and abrasive particles, resulting in a decrease in the friction coefficient. The release of lipids from the carbon surface due to temperature elevation weakened the electrical contact performance and increased the occurrence of arc erosion, thereby exacerbating carbon wear.

关键词： temperature/humidity pantograph-catenary system C/Cu wear current-carrying friction sliding electrical contact

来源：

维普期刊数据库

同方期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Triassic integrative stratigraphy,biotas,and paleogeographical evolution of the Qinghai-Tibetan Plateau and its surrounding areas

引用

Science China Earth Sciences 2024年第4期67卷 1152-1194页

作者： Guichun WU Zhansheng ji Gary GLASH Qinggao ZENG jianxin YAO Key Laboratory of Stratigraphy and Palaeontology Ministry of Natural ResourcesInstitute of GeologyChinese Academy of Geological SciencesBeijing 100037China SinoProbe Laboratory Chinese Academy of Geological SciencesBeijing 100094China Department of Geology and Environmental Sciences State University of New York-FredoniaFredoniaNY 14063USA Xizang Autonomous Region Geological and Mineral Exploration and Development Burea Lhasa 850010China

Rocks of the Qinghai-Tibetan Plateau(QTP)host abundant Triassic *** far,the well established marine fossil sequences based on ammonoids,conodonts,bivalves,brachiopods,radiolarians,and terrestrial spora-pollen sequence have become standard for biostratigraphic correlation of the *** much of Triassic time,the QTP occupied a marine setting as suggested by the dominance of marine *** main sedimentary types represented in the Triassic successions include littoral to shallow marine clastic rocks,shallow marine carbonate platform carbonates,bathyal to abyssal slope carbonates intercalated with clastic and siliceous deposits,coal-bearing clastic strata contained within paralic facies deposits,and littoral and terrestrial volcaniclastic *** deposits are organized into four stages in ascending order:(1)Early Triassic deposits that record marine transgression,including extensive shallow marine carbonate platform strata.(2)Middle Triassic Ladinian to Late Triassic Carnian deposits,including thin-bedded limestone,fine clastics,and siliceous rocks,that accumulated at greater depths than underlying Early Triassic strata and reflect the peak of the *** activity appears to have occurred in some areas during this stage.(3)Late Triassic Norian deposits that record the onset of marine regression as suggested by the widespread occurrence of platform *** is noteworthy that stage 3 deposits of the Qin-Qi-Kun area in the northernmost region of the QPT is dominated by terrestrial strata and displays evidence of local erosion.(4)Late Triassic Rhaetian littoral and shallow marine clastic and coal-bearing deposits that preserve the record of continued marine regression *** Indus-Yarlungzangbo Suture Zone(IYSZ)appears to have been the rifting axis during Triassic time as suggested by sedimentary facies trends that reflect deepening to south and ***,the Himalaya Block to the south of the IYSZ was part of the passive margin

关键词： Qinghai-Tibetan Plateau Triassic Biostratigraphy Lithostratigraphy Palaeobiogeography Sedimentary palaeogeography

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Differential Operator Approach to■quantum Groups and Their Oscillator Representations

引用

Acta Mathematica Sinica,English Series 2024年第5期40卷 1360-1374页

作者： Zhao Bing FAN ji Cheng GENG Shao Long HAN College of Mathematical Science Harbin Engineering UniversityHarbin 150001P.R.China

For a quasi-split Satake diagram,we define a modified q-Weyl algebra,and show that there is an algebra homomorphism between it and the corresponding■quantum *** other words,we provide a differential operator approach to■quantum ***,the oscillator representations of■quantum groups are *** crystal basis of the irreducible subrepresentations of these oscillator representations are constructed.

关键词： ■quantum group differential operator oscillator representation crystal basis

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Stable stripe and vortex solitons in two-dimensional spin-orbit coupled Bose-Einstein condensates

引用

Communications in Theoretical Physics 2024年第6期76卷 26-33页

作者： Yuan Guo Muhammad Idrees ji Lin Hui-jun Li Institute of Nonlinear Physics and Department of Physics Zhejiang Normal UniversityJinhua 321004China Zhejiang Institute of Photoelectronics and Zhejiang Institute for Advanced Light Source Zhejiang Normal UniversityJinhua 321004China

We present a flexible manipulation and control of solitons via Bose-Einstein *** the presence of Rashba spin-orbit coupling and repulsive interactions within a harmonic potential,our investigation reveals the numerical local solutions within the *** manipulating the strength of repulsive interactions and adjusting spin-orbit coupling while maintaining a zero-frequency rotation,diverse soliton structures emerge within the *** include plane-wave solitons,two distinct types of stripe solitons,and odd petal solitons with both single and double *** stability of these solitons is intricately dependent on the varying strength of spin-orbit ***,stripe solitons can maintain a stable existence within regions characterized by enhanced spin-orbit coupling while petal solitons are unable to sustain a stable existence under similar *** rotational frequency is introduced to the system,solitons undergo a transition from stripe solitons to a vortex array characterized by a sustained *** rotational directions of clockwise and counterclockwise are non-equivalent owing to spin-orbit *** a result,the properties of vortex solitons exhibit significant variation and are capable of maintaining a stable existence in the presence of repulsive interactions.

关键词： Bose-Einstein condensate spin-orbit coupling rotation frequency stripe solitons vortex array

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Effect of three-volt moxibustion with helium-neon laser irradiation on quality of care in patients with lumbar radiculopathy spondylosis

引用

World Journal of Clinical Cases 2024年第15期12卷 2522-2528页

作者： Xiu-Kun ji jian Li Department of Traditional Chinese Medicine The Second Hospital of Heilongjiang ProvinceHarbin 150028Heilongjiang ProvinceChina Departments of Four Neurology The Second Hospital of Heilongjiang ProvinceHarbin 150028Heilongjiang ProvinceChina

BACKGROUND Lumbar radiculopathy spondylosis is a relatively common orthopedic disease with a high incidence *** most commonly occurs in the lumbar 4-5 and lumbar 5-sacral 1 vertebrae,which account for approximately 95%of *** mostly occurs in people aged 30-50 years old and greatly affects their quality of *** To determine the effect of triple-voltage acupuncture combined with helium-neon laser irradiation on the quality of care and improvement of symptoms in patients with lumbar radiculopathy *** In this study,we selected 120 patients with lumbar radiculopathy spondylosis who were treated at our hospital between June 2019 to June *** patients were divided into control and observation groups according to the random number table method,with 60 patients in each *** in the observation group were treated with three-volt moxibustion combined with helium-neon laser irradiation,and those in the control group were treated with lumbar *** 1 month of treatment,the lumbar pain scores,lumbar spine motor functions,clinical treatment effects,and nursing satisfaction of the two groups were *** The results showed that acupuncture combined with laser irradiation significantly improved the patients'clinical symptoms,i.e.,reduced their low back pain,significantly lower numerical rating scale pain scores in the observation group than in the control group,and better lumbar spine motility than in the control group,compared to lumbar *** addition,they were cared *** treatment effectiveness rate of the observation group was 95.5%,which was significantly higher than that of the control group(81.67%).Satisfaction with care was higher than 90 points in both groups,but the difference was not statistically *** Our study provides a clinical rationale for the future treatment of patients with lumbar spine ***,further extensive research is needed for validation.

关键词： Moxibustion Laser irradiation Clinical rationale Lumbar spine Three-volt moxibustion

来源：

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

HeterMM: applying in-DRAM index to heterogeneous memory-based key-value stores

引用

Frontiers of Computer Science 2024年第4期18卷 215-217页

作者： Yunhong ji Wentao HUANG Xuan ZHOU School of Information Renmin University of ChinaBeijing 100872China School of Computing National University of SingaporeSingapore 117417Singapore School of Data Science and Engineering East China Normal UniversityShanghai 200062China

1 Introduction Emerging byte-addressable storage technologies,such as NVM(Non-Volatile Memory),provide a more cost-effective and larger-capacity alternative to DRAM(Dynamic Random Access Memory)[1],presenting new opportunities to address the high cost,limited capacity,and volatility of in-memory key-value(KV)*** efforts have been dedicated to redesigning conventional structures on ***,they were challenged by the substantial engineering cost and increased complexity to be integrated into existing ***,a general framework to apply existing indexes to KV stores on NVM becomes more attractive[2].

关键词： stores applying value

来源：

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

A novel control strategy for reproducing the floor motions of high-rise buildings by earthquake-simulating shake tables

引用

Earthquake Research Advances 2024年第1期4卷 67-75页

作者： Yuteng Cao Zhe Qu Xiaodong ji Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering MechanicsChina Earthquake AdministrationHarbin150080China Key Laboratory of Earthquake Disaster Mitigation Ministry of Emergency ManagementHarbin150080China Key Laboratory of Civil Engineering Safety and Durability of China Education Ministry Department of Civil EngineeringTsinghua UniversityBeijing100084China

To enable the experimental assessment of the seismic performance of full-scale nonstructural elements with multiple engineering parameters(EDPs),a three-layer testbed named Nonstructural Element Simulator on Shake Table(NEST)has been *** testbed consists of three consecutive floors of steel *** bottom two floors provide a space to accommodate a full-scale *** fully explore the flexibility of NEST,we propose a novel control strategy to generate the required shake table input time histories for the testbed to track the target floor motions of the buildings of interest with high *** control strategy contains two parts:an inverse dynamic compensation via simulation of feedback control systems(IDCS)algorithm and an offline iteration procedure based on a refined nonlinear numerical model of the *** key aspects of the control strategy were introduced in this *** tests were conducted to simulate the seismic responses of a full-scale office room on the 21^(st)floor of a 42-story high-rise *** test results show that the proposed control strategy can reproduce the target floor motions of the building of interest with less than 20%errors within the specified frequency range.

关键词： Shake table test Nonstructural element High-rise building Open-loop IDCS algorithm Off-line iteration

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

湖南怀化窖藏金银器

引用

中国国家博物馆馆刊 2024年第8期 112-135,F0002,I0001,I0002,161-162,F0003页

作者：谭远辉湖南省文物考古研究院长沙410125

湖南省怀化市通道县瓜地生产队,麻阳县旧县村、隆家堡乡分别于1982、1986、1993年发现了三处金银器窖藏。文物部门收集到各类金银器共64件(套),其中麻阳旧县晚唐至五代时期银器28件,通道瓜地和麻阳隆家堡明清之际金银器36件。三处窖藏... 详细信息

湖南省怀化市通道县瓜地生产队,麻阳县旧县村、隆家堡乡分别于1982、1986、1993年发现了三处金银器窖藏。文物部门收集到各类金银器共64件(套),其中麻阳旧县晚唐至五代时期银器28件,通道瓜地和麻阳隆家堡明清之际金银器36件。三处窖藏均位于河流边,埋藏年代均处于乱世,说明其成因都是属主在逃亡过程中的藏宝行为。怀化金银器窖藏对于金银器的断代以及晚唐五代和南明历史的研究均具有重要价值和意义。由于早年的发掘报道等资料均比较简略,本文在精确测量的基础上,重新考察其年代、分类、定名等问题,并举例加以介绍。

关键词：麻阳县通道县金银器晚唐至五代南明

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Surgical approaches to correct corneal astigmatism at time of cataract surgery: a mini-review

引用

International Journal of Ophthalmology(English edition) 2024年第7期17卷 1370-1374页

作者： Xiao-Lei Yin Zhi-Yang ji Xiu-Xin Li Xue-Mei Liang Shu-Xing ji Department of Ophthalmology the 305 Hospital of PLABeijing 100017China Department of Ophthalmology Daping HospitalArmy Medical UniversityChongqing 400042China Department of Medical Administration the 305 Hospital of PLABeijing 100017China

Among refractive errors,astigmatism is the most common optical aberration,where refraction changes in different meridians of the *** causes blurred vision at any distance and includes corneal,lenticular,and retinal *** surgery used to cause a progressive increase in the pre-exisiting corneal astigmatism because of creating a surgically induced astigmatism,for example,a large size surgery *** development of surgical techniques during last decades has made cataract surgery interchange to treat preoperative corneal astigmatism at time of ***,three surgical approaches can be *** placing a sutureless clear corneal incision on the steep meridian of the cornea,a preoperative corneal astigmatism less than 1.0 D can be *** or paired peripheral corneal relaxing incisions(PCRIs)provide 1.0-3.0 D corneal astigmatism *** are typically used for treating 1.0-1.5 D of regular corneal astigmatism,if more than 2.0 D,the risk of overcorrection and irregular astigmatism is *** toric intraocular lenses(IOLs)are unavailable in markets,PCRIs are still a reasonable option for patients with up to 3.0 D of pre-existing corneal *** IOLs implantation can correct 1.0-4.5 D of corneal *** IOLs are approved to correct a high degree of corneal astigmatism with cylinder power up to 12.0 *** approaches can be used alone or in combination.

关键词： cornea astigmatism cataract surgery peripheral corneal relaxing incisions toric intraocular lens

来源：

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

Flow characterization of macroporous W-4.8 vol.%ZrO2 alloy during hot deformation with improved constitutive equation and processing maps

引用

Tungsten 2024年第3期6卷 610-620页

作者： jia-Hao Ye Liu-jie Xu ji-Kang Hu School of Materials Science and Engineering Henan University of Science and Technology National Joint Engineering Research Center for Abrasion Control and Molding of Metal Materials Henan University of Science and Technology

In this work,isothermal compression experiments of macroporous W-4.8 vol.%ZrO2（W-4.8ZrO2） at 1300-1600℃ and strain rate of 0.005-1 s-1were carried out on a Gleeble-1500D thermo-mechanical *** dynamic recovery of W-4.8ZrO2is the main "softening" *** the basis of Arrhenius model,the initial constitutive equation is established by exploring the influence of temperature,strain rate and rheological *** on Arrhenius model,the relationship between flow stress,strain rate and deformation temperature is *** the influence of strain,the improved constitutive equation and the law of material constant changing with the strain are *** that,the hot processing maps were drawn on the basis of the dynamic material model,which is used to analyze the instability mechanism of the W-4.8ZrO2,and determine the appropriate hot working process parameters(temperature:1350-1450℃,strain rate:0.1-1 s-1).

关键词： Tungsten alloy Flow characteristics Constitutive equation Hot processing maps

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：