期刊文献+
共找到8,413篇文章
< 1 2 250 >
每页显示 20 50 100
Monitoring absolute vertical land motions and absolute sea-level changes from GPS and tide gauges data over French Polynesia
1
作者 Xianjie Li Jean-Pierre Barriot +2 位作者 Bernard Ducarme Marania Hopuare Yidong Lou 《Geodesy and Geodynamics》 EI CSCD 2024年第1期13-26,共14页
In this study,we estimate the absolute vertical land motions at three tidal stations with collocated Global Navigation Satellite System(GNSS)receivers over French Polynesia during the period 2007-2020,and obtain,as an... In this study,we estimate the absolute vertical land motions at three tidal stations with collocated Global Navigation Satellite System(GNSS)receivers over French Polynesia during the period 2007-2020,and obtain,as ancillary results,estimates of the absolute changes in sea level at the same locations.To verify our processing approach to determining vertical motion,we first modeled vertical motion at the International GNSS Service(IGS)THTI station located in the capital island of Tahiti and compared our estimate with previous independent determinations,with a good agreement.We obtained the following estimates for the vertical land motions at the tide gauges:Tubuai island,Austral Archipelago-0.92±0.17 mm/yr,Vairao village,Tahiti Iti:-0.49±0.39 mm/yr,Rikitea,Gambier Archipelago-0.43±0.17 mm/yr.The absolute variations of the sea level are:Tubuai island,Austral Archipelago 5.25±0.60 mm/yr,Vairao village,Tahiti Iti:3.62±0.52 mm/yr,Rikitea,Gambier Archipelago 1.52±0.23 mm/yr.We discuss these absolute values in light of the values obtained from altimetric measurements and other means in French Polynesia. 展开更多
关键词 GPS Tide gauges Sea level changes Vertical land motion
下载PDF
Unification of Gravitational and Strong Interaction Fields Using Partial Gauge Symmetry
2
作者 Young Hwan Yun Kiho Jang 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2024年第2期515-533,共19页
We propose the new field potential by maintaining both the symmetry of the scalar gauge and the conservation law keeping N?ether’s theorem, while disregarding the symmetry of the vector gauge. The new potential forms... We propose the new field potential by maintaining both the symmetry of the scalar gauge and the conservation law keeping N?ether’s theorem, while disregarding the symmetry of the vector gauge. The new potential forms like the well-type potential where a particle behaves almost freely but is very hard to escape without external energy, which can be interpreted as local confinement and asymptotic freedom. By assuming a 2-dimensional metric tensor in 4-dimensional space-time, we suggest the existence of 3 kinds of particles that resemble QCD with 3 color charges. We also show that the mass term exists but comes to zero and derive the charge and spin values. We can regard the particle with this new potential as a gluon, and the interaction in this well-type potential as a strong interaction for the properties of mass, charge, spin, and its behavior. We suggest the eight-fold way with this new particle, which is similar to the existing method based on SU (3) symmetry. Even though the strong interaction has been analyzed in the standard model and string theory, we build a new consistent model based on the theory of relativity including Riemann geometry, and show the unification of gravitational and strong interactional field. 展开更多
关键词 Strong Interaction gauge Symmetry RELATIVITY QCD CONFINEMENT Asymptotic Freedom
下载PDF
Research on the strain gauge mounting scheme of track wheel force measurement system based on high-speed wheel/rail relationship test rig
3
作者 Yuanwu Cai Bo Chen Chongyi Chang 《Railway Sciences》 2024年第4期503-513,共11页
Purpose-This paper aims to analyze the stress and strain distribution on the track wheel web surface and study the optimal strain gauge location for force measurement system of the track wheel.Design/methodology/appro... Purpose-This paper aims to analyze the stress and strain distribution on the track wheel web surface and study the optimal strain gauge location for force measurement system of the track wheel.Design/methodology/approach-Finite element method was employed to analyze the stress and strain distribution on the track wheel web surface under varying wheel-rail forces.Locations with minimal coupling interference between vertical and lateral forces were identified as suitable for strain gauge installation.Findings-The results show that due to the track wheel web’s unique curved shape and wheel-rail force loading mechanism,both tensile and compressive states exit on the surface of the web.When vertical force is applied,Mises stress and strain are relatively high near the inner radius of 710 mm and the outer radius of 1110mmof the web.Under lateral force,high Mises stress and strain are observed near the radius of 670mmon the inner and outer sides of the web.As the wheel-rail force application point shifts laterally toward the outer side,the Mises stress and strain near the inner radius of 710 mm of the web gradually decrease under vertical force while gradually increasing near the outer radius of 1110 mm of the web.Under lateral force,the Mises stress and strain on the surface of the web remain relatively unchanged regardless of the wheel-rail force application point.Based on the analysis of stress and strain on the surface of the web under different wheel-rail forces,the inner radius of 870 mm is recommended as the optimal mounting location of strain gauges for measuring vertical force,while the inner radius of 1143 mm is suitable for measuring lateral force.Originality/value-The research findings provide valuable insights for determining optimal strain gauge locations and designing an effective track wheel force measurement system. 展开更多
关键词 Track wheel High-speed wheel/rail relationship test rig Instrumented wheelset Strain gauge Finite element
下载PDF
Observation about the Classical Electromagnetic Gauge Transformation and Its Quantum Correspondence
4
作者 Gustavo V. López Jorge A. Lizarraga 《Journal of Modern Physics》 2024年第4期474-479,共6页
Using the Landau and symmetric gauges for the vector potential of a constant magnetic field and the quantum problem of a charged particle moving on a flat surface, we show the classical electromagnetic gauge transform... Using the Landau and symmetric gauges for the vector potential of a constant magnetic field and the quantum problem of a charged particle moving on a flat surface, we show the classical electromagnetic gauge transformation does not correspond to a one-dimensional unitary group transformation U(1) of the wave function for the quantum case. In addition, with the re-examination of the relation between the magnetic field B and its vector potential  A, we found that, in order to have a consistent formulation of the dynamics of the charged particle with both expressions, we must have that B=∇×A if and only if B≠0. 展开更多
关键词 gauge Transformation Harmonic Oscillator Quantum Hall Effect Electromagnetic Potentials
下载PDF
Influence of band microstructure on carbide precipitation behavior and toughness of 1 GPa-grade ultra-heavy gauge low-alloy steel 被引量:5
5
作者 Peng Han Zhipeng Liu +4 位作者 Zhenjia Xie Hua Wang Yaohui Jin Xuelin Wang Chengjia Shang 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2023年第7期1329-1337,共9页
This study investigated the influence of band microstructure induced by centerline segregation on carbide precipitation behavior and toughness in an 80 mm-thick 1 GPa low-carbon low-alloy steel plate.The quarter-thick... This study investigated the influence of band microstructure induced by centerline segregation on carbide precipitation behavior and toughness in an 80 mm-thick 1 GPa low-carbon low-alloy steel plate.The quarter-thickness(1/4t)and half-thickness(1/2t)regions of the plate exhibited similar ductility and toughness after quenching.After tempering,the 1/4t region exhibited~50%and~25%enhancements in both the total elongation and low-temperature toughness at-40°C,respectively,without a decrease in yield strength,whereas the toughness of the 1/2t region decreased by~46%.After quenching,both the 1/4t and 1/2t regions exhibited lower bainite and lath martensite concentrations,but only the 1/2t region exhibited microstructure bands.Moreover,the tempered 1/4t region featured uniformly dispersed short rod-like M_(23)C_(6)carbides,and spherical MC precipitates with diameters of~20–100 nm and<20 nm,respectively.The uniformly dispersed nanosized M_(23)C_(6)carbides and MC precipitates contributed to the balance of high strength and high toughness.The band microstructure of the tempered 1/2t region featured a high density of large needle-like M3C carbides.The length and width of the large M3C carbides were~200–500 nm and~20–50 nm,respectively.Fractography analysis revealed that the high density of large carbides led to delamination cleavage fracture,which significantly deteriorated toughness. 展开更多
关键词 band microstructure carbides TOUGHNESS heavy gauge steel centerline segregation
下载PDF
Combination of Tsoft and ET34-ANA-V80 software for the preprocessing and analysis of tide gauge data in French Polynesia 被引量:1
6
作者 Bernard Ducarme Jean-Pierre Barriot Fangzhao Zhang 《Geodesy and Geodynamics》 CSCD 2023年第1期26-34,共9页
Since 2008 a network of five sea-level monitoring stations was progressively installed in French Polynesia.The stations are autonomous and data,collected at a sampling rate of 1 or 2 min,are not only recorded locally,... Since 2008 a network of five sea-level monitoring stations was progressively installed in French Polynesia.The stations are autonomous and data,collected at a sampling rate of 1 or 2 min,are not only recorded locally,but also transferred in real time by a radio-link to the NOAA through the GOES satellite.The new ET34-ANA-V80 version of ETERNA,initially developed for Earth Tides analysis,is now able to analyze ocean tides records.Through a two-step validation scheme,we took advantage of the flexibility of this new version,operated in conjunction with the preprocessing facilities of the Tsoft software,to recover co rrected data series able to model sea-level variations after elimination of the ocean tides signal.We performed the tidal analysis of the tide gauge data with the highest possible selectivity(optimal wave grouping)and a maximum of additional terms(shallow water constituents).Our goal was to provide corrected data series and modelled ocean tides signal to compute tide-free sea-level variations as well as tidal prediction models with centimeter precision.We also present in this study the characteristics of the ocean tides in French Polynesia and preliminary results concerning the non-tidal variations of the sea level concerning the tide gauge setting. 展开更多
关键词 Tide gauges Tidal data processing Mean sea level
下载PDF
余拟群双代数的Gauge变换
7
作者 尹清红 张宇飞 方小利 《绍兴文理学院学报》 2023年第8期38-43,共6页
在余拟群双代数上利用Gauge变换构造了一个新的余拟群双代数,并且证明了两个余拟群双代数的余表示范畴是张量群等价的.
关键词 余拟群双代数 gauge变换 群范畴
下载PDF
Silicone oil injection and removal in 27-gauge vitreous surgery
8
作者 Yorihisa Kitagawa Hiroyuki Shimada +1 位作者 Masayoshi Yukita Saigen Naruse 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2023年第1期139-142,共4页
Dear Editor,The advent of 23-gauge(G),25-G,and 27-G vitrectomy systems[1]since the beginning of the 21stcentury has allowed vitrectomy via a smaller incision compared to the 20-G system;hence the name"microincisi... Dear Editor,The advent of 23-gauge(G),25-G,and 27-G vitrectomy systems[1]since the beginning of the 21stcentury has allowed vitrectomy via a smaller incision compared to the 20-G system;hence the name"microincision vitrectomy surgery".Microincision vitrectomy surgery has gainedpopularity among vitreoretinal surgeons. 展开更多
关键词 SURGERY INJECTION gauge
下载PDF
An Outline of the Grand Unified Theory of Gauge Fields
9
作者 Bi Qiao 《Journal of Modern Physics》 CAS 2023年第3期212-326,共25页
This paper attempts to propose a grand unified guiding principle of gauge fields from the mathematical and physical picture of fiber bundles: it is believed that our universe may have more fundamental interactions tha... This paper attempts to propose a grand unified guiding principle of gauge fields from the mathematical and physical picture of fiber bundles: it is believed that our universe may have more fundamental interactions than the four fundamental interactions, and the gauge fields of these fundamental interactions are just a unified gauge potential on the fiber bundle manifold or the components connected to the bottom manifold, that is, our universe;these components can meet the transformation of gauge potential, and even can be transformed from a fundamental interaction gauge potential to another fundamental interaction gauge potential, and can be summarized into a unified equation, namely the expression of the generalized gauge equation, corresponding to the gauge transformation invariance;so gauge transformation invariance is a necessary condition to unify field theory, but quantization of field is not a necessary condition;the four (or more) fundamental interaction fields of the universe are unified into a universal gauge field defined by the connection of the principal fiber bundle on the cosmic base manifold. 展开更多
关键词 gauge Field Principal Fiber Bundle gauge Transformation Invariance Grand Unified Theory of Physics
下载PDF
Water Gauge Image Denoising Model Based on Improved Adaptive Total Variation 被引量:1
10
作者 SHI Zhenting ZHOU Xianchun +2 位作者 ZHANG Ying LI Ting LU Siqi 《Instrumentation》 2023年第1期59-68,共10页
As an important part of water level warning in water conservancy projects,often due to the influence of environmental factors such as light and stains,the acquired water gauge images have sticky,broken and bright spot... As an important part of water level warning in water conservancy projects,often due to the influence of environmental factors such as light and stains,the acquired water gauge images have sticky,broken and bright spot conditions,which affect the identification of water gauges.To solve this problem,a water gauge image denoising model based on improved adaptive total variation is proposed.Firstly,the regular term exponent in the adaptive total variational equation is changed to an inverse cosine function;secondly,the differential curvature is used to distinguish the image noise points and increase the smoothing strength at the noise points;finally,according to the characteristics of the gradient mode and adaptive gradient threshold after Gaussian filtering,the New model can adaptively denoise in the smooth area and protect the edge area,so as to have the characteristics of both edge-preserving denoising.The experimental results show that the new model has a great improvement in image vision,higher iteration efficiency and an average increase of 1.6 dB in peak signal-to-noise ratio,and an average increase of 9%in structural similarity,which is more beneficial to practical applications. 展开更多
关键词 Water gauge Image Adaptive Total Variation Differential Curvature Gradient Mode Adaptive Gradient Threshold
下载PDF
Integration of Transport and Land Use Planning by Transit-Oriented Development for Economic Sustainability of the Standard Gauge Railway Projects in Tanzania
11
作者 Emmanuel Elifadhili Mchome Uwezo Wilbard Nzoya 《Journal of Transportation Technologies》 2023年第4期756-771,共16页
Tanzania is one of the countries in Africa that has engaged in the projects for construction of the electrified Standard Gauge Railway (SGR). However, lack of integration of transportation and land-use planning threat... Tanzania is one of the countries in Africa that has engaged in the projects for construction of the electrified Standard Gauge Railway (SGR). However, lack of integration of transportation and land-use planning threatens economic sustainability of the SGR project. This study was carried out for the purpose of finding-out how transportation can be integrated with land-use planning for economic sustainability of the project. The study was carried-out by using qualitative research approach through demonstration as case study. Findings show that construction of the SGR is not integrated with land-use planning around the stations and along the SGR corridor. It is concluded that economic sustainability of the SGR projects can be achieved by integration of transport and land-use planning. As demonstrated, it is recommended to deliberate for integration of transportation and land-use planning in the SGR projects of which the prime land within Transit Stations can be efficiently used by using Transit Oriented Development and secure more land for production activities around the Transit Stations and along the SGR corridor. 展开更多
关键词 Economic Sustainability Standard gauge Railway Land Planning Transit-Oriented Development SGR Transit Stations
下载PDF
The Significance of Generalized Gauge Transformation across Fundamental Interactions
12
作者 Bi Qiao 《Journal of Modern Physics》 CAS 2023年第5期604-622,共19页
The author of this paper has put forward a unified program of gauge field from the mathematical and physical picture of the principal associated bundles: thinking that our universe may have more fundamental interactio... The author of this paper has put forward a unified program of gauge field from the mathematical and physical picture of the principal associated bundles: thinking that our universe may have more fundamental interactions than the four fundamental interactions, and these basic interaction gauge fields are only the projection components to the base manifold, that is our universe, from a unified gauge potential or connection of the principal associated bundle manifold on the base manifold. These components can satisfy the transformation of gauge potential, and can even be transformed from one basic interaction gauge potential to another basic interaction gauge potential, and can be summarized into a unified equation, that is, the generalized gauge Equation (GGE), but the gauge potential or connection on the principal bundle is invariant, corresponding to the invariance of gauge transformation [1]. In this paper, we will continue to discuss this aspect concretely, and specifically construct a spatiotemporal model with the frame bundle as the principal bundle, and the tensor bundle as the associated bundle, so that the four fundamental interactions, especially the electromagnetic interaction and the gravitational interaction, can be reflected in the bottom manifold, that is, the regional distributions in our universe. Furthermore, this paper studies the existence of gauge transformation across basic interactions by establishing a model of gauge transformation of basic interaction field;it is found that the unified expression formula is GGE and the expression relation on the curvature of space-time. Therefore, the author discusses the feasibility of the generalized gauge transformation across the basic electromagnetic interaction and the basic gravitational interaction, and on this basis, specifically determines a method or way to find the generalized gauge transformation, so as to try to realize the last step of the “unification” of the four fundamental interactions in physics, that is, the “unification” of electromagnetism and gravity. 展开更多
关键词 Generalized gauge Transformation Unification of Fundamental Interactions Principal Bundle Connection and Curvature
下载PDF
Challenges of the Performance Standards of the International Finance Corporation in Financing the African Integrated High-Speed Railway Network and the Way Forward: The Case of Standard Gauge Railway in Tanzania
13
作者 Emmanuele Elifadhili Mchome Uwezo Wilbard Nzoya 《Journal of Transportation Technologies》 2023年第4期772-788,共17页
Financing of the African Integrated High-Speed Railway Network (AIHSRN) through Standard Gauge Railway (SGR) Projects is very expensive. As a result, most of the African countries seek financial supports from the Inte... Financing of the African Integrated High-Speed Railway Network (AIHSRN) through Standard Gauge Railway (SGR) Projects is very expensive. As a result, most of the African countries seek financial supports from the International Financial Institutions (IFIs). However, conditions provided by the IFIs through the Performance Standards (PS) of the International Financial Corporation (IFC) increase cost of the projects and thus, it becomes a burden to most of the African countries. This study aimed to explore the causes of IFC-PS through the SGR Projects that escalate costs and how to address them. The Tanzania SGR Lot 1 Project that covered 205 km from Dar es Salaam to Morogoro was selected as a case study. The methods used for data collection involved literature review, focus group discussions and interviews. The results and findings show a gap between the IFC-PS and the National Laws and Regulations that escalates costs of the projects if funds from the IFIs were to be secured. To bridge the gap, it is recommended that the African countries should engage into negotiations with the IFIs to agree to waive IFC-PS conditions that escalate costs provided they are adequately covered in the national laws and regulations;engagement of locally established national and regional financial institutions;and the responsible government institutions in the African countries should sit together for assessment and review of the IFC-PS against the national laws and regulations. 展开更多
关键词 African Integrated High-Speed Railway Network International Financial Institutions Standard gauge Railway Performance Standards
下载PDF
复杂场景下无水尺水位的影像水位反演智能检测方法 被引量:1
14
作者 孙传猛 魏宇 +2 位作者 李欣宇 马铁华 武志博 《测绘学报》 EI CSCD 北大核心 2024年第3期558-568,共11页
实现精细化水务管控和洪涝灾害预警,需要实时、准确感知水位突变事件。现有技术不能满足夜晚、雾霾、雨天、雪天、漂浮物遮挡及阴影等复杂恶劣环境下的水位识别需求。为此,本文提出一种融合改进YOLOv5与卡尔曼滤波原理的无水尺水位智能... 实现精细化水务管控和洪涝灾害预警,需要实时、准确感知水位突变事件。现有技术不能满足夜晚、雾霾、雨天、雪天、漂浮物遮挡及阴影等复杂恶劣环境下的水位识别需求。为此,本文提出一种融合改进YOLOv5与卡尔曼滤波原理的无水尺水位智能检测技术:①引入YOLOv5对水位线(水岸分界线)进行检测,并利用线性拟合方法获得实际水位线;②针对水位线在延伸方向无限大而在其法向无限小特点,提出强化中尺度特征的多层级特征融合方法改进原YOLOv5算法;③利用卡尔曼滤波引入水位历史信息作为先验知识,提高本技术对复杂恶劣环境的泛化性能;④将图像中事先标定的固定的标志物加入到深度学习网络中训练,根据标志位真实尺寸解算实际水位高程,实现无水尺检测方案。相关试验和实践表明,改进的YOLOv5更加轻量化;本文所述水位智能检测技术斜率准确性为97.3%,较原算法提高了2.4%;截距准确性为99.3%,较原算法提高了0.5%;在夜晚、雾霾、雨天、雪天、漂浮物遮挡及阴影等复杂恶劣环境下可以自动、准确识别出水位高程,误差小于0.1 m。 展开更多
关键词 水位识别 无水尺水位检测 深度学习 YOLOv5 卡尔曼滤波
下载PDF
基于热容法测量的卫星推进剂剩余量仿真分析
15
作者 黄滨 陈佳呈 +2 位作者 李文 刘锦涛 王璐 《空间控制技术与应用》 CSCD 北大核心 2024年第5期101-112,共12页
热容法是具有主动热源输入的卫星推进剂剩余量测量方法,该方法是通过在贮箱表面安装特定功率加热片同时获取测点温度变化数据的方式推算推进剂剩余量.为获得微重力环境下准确的热分析模型,针对板式贮箱在轨环境下的气液分布特点,基于计... 热容法是具有主动热源输入的卫星推进剂剩余量测量方法,该方法是通过在贮箱表面安装特定功率加热片同时获取测点温度变化数据的方式推算推进剂剩余量.为获得微重力环境下准确的热分析模型,针对板式贮箱在轨环境下的气液分布特点,基于计算流体力学(computational fluid dynamics,CFD)方法对贮箱热容法进行数值仿真,研究不同加速度条件、填充比与测点位置对热容法精度的影响.结果表明,在微重力环境下,推进剂受微重力影响沿导流板向上爬升,推进剂浸润的贮箱壁面面积更大,从而导致贮箱的温度分布与地面工况存在明显差异.通过研究发现,在微重力工况下,当测点分布于远离热源处时,测点的温度分辨率更高,热容法的测量精度更高. 展开更多
关键词 热容法 微重力环境 板式表面张力贮箱 推进剂 剩余量测量方法
下载PDF
区段煤柱变形光纤光栅监测应用研究 被引量:1
16
作者 柴敬 王佳琪 +5 位作者 杨健锋 高登彦 高奎英 陈建华 刘泽宇 杨磊 《煤炭科学技术》 EI CAS CSCD 北大核心 2024年第1期126-137,共12页
针对近距离煤层下伏工作面过上覆遗留煤柱时,发生动静载叠加诱发强矿压显现,导致区段煤柱发生变形失稳造成人员伤亡和设备破坏。为探索基于光纤光栅实时监测区段煤柱变形发育特征,分析进、出遗留煤柱阶段矿压显现机理,将FBG、光栅应力... 针对近距离煤层下伏工作面过上覆遗留煤柱时,发生动静载叠加诱发强矿压显现,导致区段煤柱发生变形失稳造成人员伤亡和设备破坏。为探索基于光纤光栅实时监测区段煤柱变形发育特征,分析进、出遗留煤柱阶段矿压显现机理,将FBG、光栅应力计的光测方法相结合,结合现场实测的区段煤柱变形应力应变水平参量变化规律,研究煤柱应变空间分布规律及回采过程中工作面前方煤柱内部应变时域响应特征,验证光测方法在煤体应变水平观测的可行性。结果表明:工作面回采经过上覆遗留煤柱期间,区段煤柱顶板受集中应力影响,上部岩层块体破断并发生回转导致煤柱载荷增加,随着工作面推进覆岩断裂进一步向上传递,关键层断裂回转发生导致工作面来压,最终导致区段煤柱变形失稳。根据现场光栅应变增量幅度判断煤柱内局部变形的剧烈程度,在集中应力作用下,区段煤柱变形时发生最大应变为650×10^(-6),上覆岩层集中应力造成煤柱应变水平峰值位置为煤柱宽度11.5 m,沿煤柱宽度方向应变表现出先增加后减小然后趋于稳定的趋势,内部应变随采动过程中影响范围在5 m左右。综合研究工作面回采经过上覆遗留煤柱时应变对区段煤柱发生变形失稳的特点和规律,以及应变水平变化和煤柱物理力学性质,得到煤柱破坏的前兆特征,在外力作用下达到变形峰值前对煤柱提前进行卸压和防护的安全处理。 展开更多
关键词 区段煤柱 遗留煤柱 矿压显现 光纤光栅 光栅应力计 实时监测
下载PDF
通井规携屑性能研究结构及参数优化
17
作者 杨建 王汉 +2 位作者 李玉飞 唐庚 张林 《石油矿场机械》 CAS 2024年第5期48-53,共6页
针对一体化井筒准备作业中岩屑通过通井规效果差,导致通井规携屑能力低的问题,以携屑能力为性能指标,采用正交试验法对通井规进行结构优化设计,得到了最优结构参数:过流道深度6 mm、过流道螺旋角度80°、过流道宽度40 mm、扶正套锥... 针对一体化井筒准备作业中岩屑通过通井规效果差,导致通井规携屑能力低的问题,以携屑能力为性能指标,采用正交试验法对通井规进行结构优化设计,得到了最优结构参数:过流道深度6 mm、过流道螺旋角度80°、过流道宽度40 mm、扶正套锥角11°;同时以最优结构参数对通井规作业参数进行优选,优选出最佳作业参数:循环排量1.1 m^(3)/min、转速60 r/min。研究结果表明,对通井规结构参数优化和作业参数优选,提高了通井规携屑能力,为通井规结构参数和工况参数的优化研究提供了参考,具有指导和借鉴意义。 展开更多
关键词 通井规 结构优化 正交试验 携屑能力
下载PDF
Gleeble高温拉伸样品标距段的选定对拉伸曲线的影响
18
作者 赵冠琳 吴东亭 +3 位作者 刘树帅 王建峰 乔营 宋浩泽 《实验技术与管理》 CAS 北大核心 2024年第8期15-21,共7页
Gleeble热模拟试验机是目前测定金属材料在高温条件下力学性能的主要设备之一。利用该设备进行高温拉伸试验时,样品属于局部加热,中间温度最高,向两侧随距离增大温度呈现递减状态,因此常选用温差在50~100℃范围内的区域作为标距段长度... Gleeble热模拟试验机是目前测定金属材料在高温条件下力学性能的主要设备之一。利用该设备进行高温拉伸试验时,样品属于局部加热,中间温度最高,向两侧随距离增大温度呈现递减状态,因此常选用温差在50~100℃范围内的区域作为标距段长度来获取最终的拉伸曲线。该文选取了两种棒材和两种板材,对其分别进行600、800和1000℃的高温处理,获得不同样品的加热区域温度分布情况,进而给出推荐的标距段长度。随后对4种样品分别进行800℃、应变速率0.1/s下的高温拉伸试验,获得不同标距长度下样品的高温拉伸曲线。通过对曲线结果进行分析,给出利用该设备进行高温拉伸时的样品选用和标距范围的建议。 展开更多
关键词 高温力学性能 拉伸曲线 标距
下载PDF
MEMS电容薄膜真空计微电容检测系统的设计
19
作者 高青松 郭朝帽 +3 位作者 陶院 杨雷 马动涛 张虎忠 《真空与低温》 2024年第6期603-609,共7页
为了满足空间环境探测对真空测量仪器准确度高、体积小、质量轻、功耗低的应用需求,基于微机电系统(MEMS)的小型化电容薄膜真空计应运而生。针对MEMS电容薄膜真空计微小电容测量需求,设计了一种基于CDC电容数字转换器的微电容检测系统,... 为了满足空间环境探测对真空测量仪器准确度高、体积小、质量轻、功耗低的应用需求,基于微机电系统(MEMS)的小型化电容薄膜真空计应运而生。针对MEMS电容薄膜真空计微小电容测量需求,设计了一种基于CDC电容数字转换器的微电容检测系统,获得了fF级微电容检测分辨率。采用温度漂移误差自校准技术,解决了测量压力受温度扰动影响的问题。地面样机测试与验证表明,该检测系统具有宽量程、高分辨率和低功耗检测的优点,为MEMS电容薄膜真空计实现空间应用奠定了技术基础。 展开更多
关键词 MEMS 电容薄膜 真空计 微弱电容 电子测量
下载PDF
薄膜热流计与原子层热电堆热流传感器的激波风洞试验对比
20
作者 陈苏宇 刘济春 +3 位作者 杨凯 朱涛 朱新新 王辉 《实验流体力学》 CAS CSCD 北大核心 2024年第5期90-97,共8页
激波风洞试验的主要测试量是热流密度,且多采用薄膜热流计进行测试,但薄膜热流计热流测试结果缺乏直接验证手段,存在测热结果不确定度偏大等问题。原子层热电堆(ALTP)热流传感器响应时间短且线性度好,结合高精度可溯源的热流传感器标定... 激波风洞试验的主要测试量是热流密度,且多采用薄膜热流计进行测试,但薄膜热流计热流测试结果缺乏直接验证手段,存在测热结果不确定度偏大等问题。原子层热电堆(ALTP)热流传感器响应时间短且线性度好,结合高精度可溯源的热流传感器标定实验,可保证ALTP热流传感器测热结果的准确性和可靠性。在多个流场条件下的激波风洞试验中开展了薄膜热流计和ALTP热流传感器测热结果交叉对比验证。对比试验显示:ALTP热流传感器和薄膜热流计在不同流场参数下测热结果相对稳定,中高热流下两者测热结果相差在8%以内。结合对比标定溯源链以及激波风洞试验测热结果的讨论,展现了利用ALTP热流传感器在激波风洞试验中在线标定薄膜热流计的可行性。 展开更多
关键词 热流密度 薄膜热流计 原子层热电堆 激波风洞 在线标定
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部