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Direct Pointwise Comparison of FE Predictions to StereoDIC Measurements:Developments and Validation Using Double Edge-Notched Tensile Specimen
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作者 Troy Myers Michael A.Sutton +2 位作者 Hubert Schreier Alistair Tofts Sreehari Rajan Kattil 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第8期1263-1298,共36页
To compare finite element analysis(FEA)predictions and stereovision digital image correlation(StereoDIC)strain measurements at the same spatial positions throughout a region of interest,a field comparison procedure is... To compare finite element analysis(FEA)predictions and stereovision digital image correlation(StereoDIC)strain measurements at the same spatial positions throughout a region of interest,a field comparison procedure is developed.The procedure includes(a)conversion of the finite element data into a triangular mesh,(b)selection of a common coordinate system,(c)determination of the rigid body transformation to place both measurements and FEA data in the same system and(d)interpolation of the FEA nodal information to the same spatial locations as the StereoDIC measurements using barycentric coordinates.For an aluminum Al-6061 double edge notched tensile specimen,FEA results are obtained using both the von Mises isotropic yield criterion and Hill’s quadratic anisotropic yield criterion,with the unknown Hill model parameters determined using full-field specimen strain measurements for the nominally plane stress specimen.Using Hill’s quadratic anisotropic yield criterion,the point-by-point comparison of experimentally based full-field strains and stresses to finite element predictions are shown to be in excellent agreement,confirming the effectiveness of the field comparison process. 展开更多
关键词 StereoDIC spatial co-registration data transformation finite element simulations point-wise comparison of measurements and FEA predictions double edge notch specimen model validation
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Comparison of Beijing MST Radar and Radiosonde Horizontal Wind Measurements 被引量:4
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作者 Yufang TIAN Daren LU 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2017年第1期39-53,共15页
To determine the performance and data accuracy of the 50 MHz Beijing Mesosphere-Stratosphere-Troposphere (MST) radar, comparisons of radar measured horizontal winds in the height range 3-25 km with radiosonde observ... To determine the performance and data accuracy of the 50 MHz Beijing Mesosphere-Stratosphere-Troposphere (MST) radar, comparisons of radar measured horizontal winds in the height range 3-25 km with radiosonde observations were made during 2012. A total of 427 profiles and 15 210 data pairs were compared. There was very good agreement between the two types of measurement. Standard deviations of difference (mean difference) for wind direction, wind speed, zonal wind and meridional wind were 24.86° (0.77°), 3.37 (-0.44), 3.33 (-0.32) and 3.58 (-0.25) m s^-1, respectively. The annual standard deviations of differences for wind speed were within 2.5-3 m s^-1 at all heights apart from 10-15 km, the area of strong winds, where the values were 3-4 m s^-1. The relatively larger differences were mainly due to wind field variations in height regions with larger wind speeds, stronger wind shear and the quasi-zero wind layer. A lower MST radar SNR and a lower percentage of data pairs compared will also result in larger inconsistencies. Importantly, this study found that differences between the MST radar and radiosonde observations did not simply increase when balloon drift resulted in an increase in the real-time distance between the two instruments, but also depended on spatiotemporal structures and their respective positions in the contemporary synoptic systems. In this sense, the MST radar was shown to be a unique observation facility for atmospheric dynamics studies, as well as an operational meteorological observation system with a high temporal and vertical resolution. 展开更多
关键词 MST radar RADIOSONDE horizontal wind measurement comparison and analysis
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Multi-channel FIR Interferometer for Electron Density Measurement on HT-7 Superconducting Tokamak
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作者 揭银先 高翔 +2 位作者 程永飞 杨坤 童兴德 《Plasma Science and Technology》 SCIE EI CAS CSCD 2000年第1期105-109,共5页
A five-channel far-infrared (FIR) hydrogen cyanide (HCN) laser interferometer was developed to measure plasma electron density profile on the HT-7 superconducting tokamak. The principle and structure of the five-chann... A five-channel far-infrared (FIR) hydrogen cyanide (HCN) laser interferometer was developed to measure plasma electron density profile on the HT-7 superconducting tokamak. The principle and structure of the five-channel FIR laser interferometer is described. The laser source used in the interferometer was a continuous wave glow discharge HCN laser with a 3.4 m cavity length and a 100 mW power output at 337μm wavelength. The temporal resolution was 0.1 ms and the detection sensitivity was 1/12 fringe. Preliminary experimental results measured by the interferometer on HT-7 tokamak are reported. 展开更多
关键词 FIR multi-channel FIR Interferometer for Electron Density measurement on HT-7 Superconducting Tokamak HT
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Comparison of bulk snow density measurements using different methods
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作者 Hang SU Xin-Yue ZHONG +3 位作者 Bin CAO Yuan-Tao HU Lei ZHENG Tingjun ZHANG 《Advances in Climate Change Research》 SCIE CSCD 2024年第4期658-668,共11页
Snow density is one of the basic properties used to describe snow cover characteristics,and it is critical for remote sensing retrieval,water resources assessment and modeling inputs.There are many instruments availab... Snow density is one of the basic properties used to describe snow cover characteristics,and it is critical for remote sensing retrieval,water resources assessment and modeling inputs.There are many instruments available to measure snow density in situ.However,there are mea-surement errors of snow density for bulk and layers or gravimetric and electronic instruments,which may affect the accuracy of remote sensing retrieval and model simulation.Especially in China,due to the noticeable heterogeneity of snowpacks,it is necessary to evaluate in detail the performance and applicability of snow density instruments in different snowpack conditions.This study evaluated the performance of different snow density instruments:the Federal Sampler,the model VS-43 snow density cylinder(VS-43),the wedge snow density cutter(WC1000 and WC25O),and the Snow Fork.The average bulk snow density of all instrument measurements was set as the reference value for evaluation.The results showed that as compared with the reference,the VS-43 cylinder presented the best performance for bulk snow density measurement in the measured range with the lowest RMSE(11 kg m^(-3)),BIAS(3 kg m^(-3)),and MRE(1.6%).For layer observation,bulk snow density was overestimated by 8.1%with WC1000 and underestimated by 11.4%with Snow Fork which was the worst performance compared with the reference value,and there were greater measurement errors of snow density in the depth hoar than other snow layers.Compared with grassland,the uncertainty of snow density measurements was slightly lower in forests.Overall,the Federal Sampler and VS-43 cylinder are more suitable for bulk snow density measurement in deep snowpack regions across China,and it is recommended to use WC1000,WC250 and Snow Fork to measure the snow density of snow layers in the snow stratigraphy. 展开更多
关键词 Snowdensity measurement Uncertainty comparison
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Measurement invariance and latent mean differences of the Chinese version physical activity self-efficacy scale across gender and education levels 被引量:1
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作者 Han Chen Jun Dai Yong Gao 《Journal of Sport and Health Science》 SCIE 2019年第1期46-54,共9页
Background: Self-efficacy has been identified as an important determinant of youth's behavior change including physical activity(PA) participation. However, the dimensionality check of a PA self-efficacy scale has... Background: Self-efficacy has been identified as an important determinant of youth's behavior change including physical activity(PA) participation. However, the dimensionality check of a PA self-efficacy scale has rarely been conducted in China. The current study aims to examine(1) the unidimensionality of a shortened Chinese version of PA self-efficacy scale(S-PASESC);(2) the measurement invariance of S-PASESC across gender and levels of education;(3) the latent factor mean difference between gender and levels of education;(4) the direct effects of self-efficacy on PA by different gender and education levels; and(5) the comparisons of the direct effects of self-efficacy on PA across gender and education levels.Methods: The participants were 5 th through 11 th grade public school students recruited from 7 cities located in different geographic regions of China. The final data include a total of 3003 participants(49.7% boys) who have completed the scales.Results: Confirmatory factor analysis(CFA) test supported the unidimensionality of S-PASESC. The S-PASESC is invariant across gender and 3 levels of education at both configural, full metric, and full scalar levels. Findings from latent mean comparisons showed that boys reported higher PA self-efficacy than girls. Students' perceived PA self-efficacy tend to decrease from elementary to high school. Finally, self-efficacy positively related to PA by groups of different gender and education levels and the relationship between self-efficacy and PA is stronger among middle school boys than girls.Conclusion: Findings suggest S-PASESC is a valid scale for measuring Chinese students' PA self-efficacy. 展开更多
关键词 Chinese adolescents Education levels Factor analysis GENDER LATENT mean comparison measurement INVARIANCE Physical activity SELF-EFFICACY scale
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Quantitative comparison of similarity measure and entropy for fuzzy sets
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作者 JUNG Dong-yean CHOI Jung-Wook +1 位作者 PARK Wook-Je LEE Sang-Hyuk 《Journal of Central South University》 SCIE EI CAS 2011年第6期2045-2049,共5页
Comparison and data analysis with the similarity measures and entropy for fuzzy sets were carried out. The distance proportional value between the fuzzy set and the corresponding crisp set was considered by the fuzzy ... Comparison and data analysis with the similarity measures and entropy for fuzzy sets were carried out. The distance proportional value between the fuzzy set and the corresponding crisp set was considered by the fuzzy entropy. The relation between the similarity measure and the entropy for fuzzy set was also analyzed. The fuzzy entropy was reformulated as the dissimilarity measure. Furthermore, crisp set having the minimum uncertainty with respect to the corresponding fuzzy set was also proposed. Finally, derivation of a similarity measure from entropy with the help of total information property was derived. A simple example shows the relation between similarity measure and fuzzy entropy, in which the summation of similarity measure and fuzzy entropy represents a constant value. 展开更多
关键词 similarity measure fuzzy entropy minimum uncertainty quantitative comparison
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Comparison of Digital Maps: Recognition and Quantitative Measure of Changes
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作者 Lev Spivak Ivan Spivak +1 位作者 Alexey Sokolov Sergey Voinov 《Journal of Geographic Information System》 2014年第5期415-422,共8页
A new methodology of comparing digital raster maps was proposed which allows not only detecting changes in the maps, but also obtaining quantitative measures of the importance of selected differences. Procedure of obj... A new methodology of comparing digital raster maps was proposed which allows not only detecting changes in the maps, but also obtaining quantitative measures of the importance of selected differences. Procedure of object interpretation of satellite images and forming of OMT (Object Map of Territory) is described. A list of allowable differences between two OMTs is defined. Two steps technique of quantitative measuring is proposed. At the first stage functions are constructed for calculating local measures of differences in the amount, areas and locations of objects on the map, as well as relations between the objects. In the second stage local measures are used to calculate the integral measure in order to get generalized assessment of difference between maps. The methods for constructing functions which calculate local and integral measures of differences are described. Examples of comparing and measuring the differences between OMTs are provided. Obtained results by utilizing this technique can be used to analyze trends, forecast of development and might be helpful for choosing most efficient scenarios for sustainable spatial planning and land management. 展开更多
关键词 MAPS comparison Object Map of TERRITORY Change Detection Local measurE of DIFFERENCE INTEGRAL measurE of DIFFERENCE Sustainable Spatial Planning and Land Management
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A Study on Applications and Case Studies Regarding Bluetooth Technology for Travel Time Measurement
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作者 Dian Yuan Ardeshir Faghri Katherine Partridge 《Journal of Transportation Technologies》 2020年第1期65-87,共23页
Bluetooth technology emerged over twenty years ago and has continuously improved throughout the years to meet diverse and complex applications. Initially invented to replace the need for physical data cables, Bluetoot... Bluetooth technology emerged over twenty years ago and has continuously improved throughout the years to meet diverse and complex applications. Initially invented to replace the need for physical data cables, Bluetooth offers users a quick and easy way to share data files over a wireless network. Traffic engineers and transportation engineering researchers have utilized the potential opportunities that exist with Bluetooth and have implemented this technology into traffic monitoring techniques. To gain a better understanding of Bluetooth sensors and how they work, a comprehensive literature search was conducted. Twenty-five articles were studied regarding case studies of Bluetooth sensor implementation for travel time measurement. Besides reviewing the literature and previous case studies, three new case studies in the State of Delaware, USA, were also conducted and carefully analyzed. The benefits and drawbacks associated with Bluetooth technology for travel time measurements have been identified in this paper. The overall conclusion of the authors is Bluetooth alone and by itself is not a proper technology for travel time measurements. More studies need to be conducted on the accuracy and overall application, before one can confidently utilize the Bluetooth technology for travel time measurements. 展开更多
关键词 TRAVEL Time measurement BLUETOOTH Technology comparison APPLICATIONS LITERATURE REVIEW Case Studies
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Contrast and Comparison Between the Old and New Bar Code for Commodity Management Measures
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作者 Huang Xiaolin & Ma Jing Vice President of Guizhou Information Institute of Quality Technology Supervision Deputy Director of Branch Numbering Center of Guizhou. 《China Standardization》 2005年第6期17-21,共5页
With the development of socialism market economy, the former Bar Code ForCommodity Management Measures (being called Old Measures for short hereafter) issued by the NationalBureau of Quality and Technical Supervision ... With the development of socialism market economy, the former Bar Code ForCommodity Management Measures (being called Old Measures for short hereafter) issued by the NationalBureau of Quality and Technical Supervision can not adapt to the requirement of managing for barcode for commodity. Therefore, for the purpose of standardize bar code for commodity managementstandard, ensuring its quality, speeding up the application of it in electronic business andcirculating field and accelerating the course of being a well informed country, a new Bar Code ForCommodity Management Measures (New Measures for short) has been issued by the General Administratorof Quality Supervision, Inspection and Quarantine of P.R. China (AQSIQ) on May 30th, 2005, and putinto force in October, 2005. At the same time, the Old Measures issued on July 3rd, 1998 has beenabolished. 展开更多
关键词 Pro Contrast and comparison Between the Old and New Bar Code for Commodity Management measures UCC EAN
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ANTICIPATED BACKWARD STOCHASTIC VOLTERRA INTEGRAL EQUATIONS WITH JUMPS AND APPLICATIONS TO DYNAMIC RISK MEASURES
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作者 缪亮亮 陈燕红 +1 位作者 肖肖 胡亦钧 《Acta Mathematica Scientia》 SCIE CSCD 2023年第3期1365-1381,共17页
In this paper, we focus on anticipated backward stochastic Volterra integral equations(ABSVIEs) with jumps. We solve the problem of the well-posedness of so-called M-solutions to this class of equation, and analytical... In this paper, we focus on anticipated backward stochastic Volterra integral equations(ABSVIEs) with jumps. We solve the problem of the well-posedness of so-called M-solutions to this class of equation, and analytically derive a comparison theorem for them and for the continuous equilibrium consumption process. These continuous equilibrium consumption processes can be described by the solutions to this class of ABSVIE with jumps.Motivated by this, a class of dynamic risk measures induced by ABSVIEs with jumps are discussed. 展开更多
关键词 anticipated backward stochastic Volterra integral equations comparison theorems dynamic risk measures
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中、美、日、韩新能源汽车产业竞争优势测度与比较研究——以锂电池汽车为例 被引量:5
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作者 杨武 宋晓晴 《中国科技论坛》 CSSCI 北大核心 2024年第2期180-188,共9页
本文基于中、美、日、韩近30年在锂电池汽车领域的专利数据,选取20个关键指标构建“技术-经济-法律”三维分析模型,并划分出关键核心专利,在此基础上应用景气综合指数法计算四国在锂电池汽车产业的竞争优势指数,并对其进行比较与分析。... 本文基于中、美、日、韩近30年在锂电池汽车领域的专利数据,选取20个关键指标构建“技术-经济-法律”三维分析模型,并划分出关键核心专利,在此基础上应用景气综合指数法计算四国在锂电池汽车产业的竞争优势指数,并对其进行比较与分析。结果表明,中、美、日、韩在锂电池汽车领域的总体发展布局已基本到达顶峰,且于近两年呈现波动下降趋势。总体来看,美国获得竞争优势时间最早且指数发展趋势最为稳定,连续多年稳居第一;中国获得竞争优势时间最晚,但指数发展速度最快,截至2021年末,中国总体竞争优势指数与美国持平,远超日、韩两国。分维度来看,中、美分别于经济、技术维度具有绝对竞争优势;韩国在经济、法律维度发展较为稳定,但技术维度影响整体,导致整体呈现波动下降趋势;日本在各维度均呈现出明显下降趋势,仅在技术维度下降幅度较小。由此得出结论:中国经济发展带动整体,已基本实现锂电池汽车产业的技术赶超,技术维度的发展是获得持续性竞争优势的基础,因此应在保持现有锂电池汽车领域竞争优势的同时注重相关技术轨道的跨越与变迁,以获取新能源汽车产业的持续性竞争优势。 展开更多
关键词 新能源汽车 锂电池 竞争优势 测度与比较 关键核心专利
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声校准器声压级计量比对研究
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作者 鄂治群 周承毅 +1 位作者 孙磊 康小东 《中国测试》 CAS 北大核心 2024年第S01期234-237,共4页
声校准器是空气声声压量值传递的主要标准器之一,既作为声学计量标准中的标准器,又作为计量器具广泛应用。为考察国内实验室声校准器声压级测量量值准确一致程度,考核声校准器计量标准、环境条件、人员水平、方法、数据处理、管理能力... 声校准器是空气声声压量值传递的主要标准器之一,既作为声学计量标准中的标准器,又作为计量器具广泛应用。为考察国内实验室声校准器声压级测量量值准确一致程度,考核声校准器计量标准、环境条件、人员水平、方法、数据处理、管理能力等方面的实际水平和能力,国家市场监督管理总局组织了声校准器声压级量值计量比对,中国测试技术研究院作为主导实验室,参比实验室包括主导实验室在内的6家国内计量技术机构。文章介绍了声校准器声压级的测量原理与比对实施过程,应用归一化偏差对测量数据进行处理,分析了比对数据与结果,验证了参比实验室的比对结果具有较好的一致性,针对一些技术问题提出了建议与解决方法。 展开更多
关键词 声校准器 计量比对 声压级 不确定度
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在片S参数计量比对结果浅析
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作者 刘晨 高岭 +7 位作者 栾鹏 陈婷 黄英龙 李艳奎 金诚 邹喜跃 陆景 陈科元 《计量学报》 CSCD 北大核心 2024年第9期1401-1406,共6页
中国电子科技集团公司第十三研究所作为主导实验室开展了在片S参数计量比对工作,对参比实验室提交的在片S参数测量结果进行了汇总分析,并用E_n值对各参比实验室测量结果进行了评价。通过在片S参数计量比对,确保了量值传递的准确、可靠,... 中国电子科技集团公司第十三研究所作为主导实验室开展了在片S参数计量比对工作,对参比实验室提交的在片S参数测量结果进行了汇总分析,并用E_n值对各参比实验室测量结果进行了评价。通过在片S参数计量比对,确保了量值传递的准确、可靠,特别是对在片S参数测量不确定度的主要来源统一了认识。同时也为业内提供了在片S参数测量一致性的比较平台。 展开更多
关键词 无线电计量 在片S参数 计量比对 矢量网络分析仪
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论齿轮样板
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作者 林虎 石照耀 《仪器仪表学报》 EI CAS CSCD 北大核心 2024年第6期240-255,共16页
齿轮样板是齿轮参数量值的标准实物载体,用于将齿轮国家测量标准所复现的量值传递到各级齿轮测量仪器上,从而实现齿轮测量的准确性和一致性,保证齿轮产品质量。全面概述了齿轮样板起源及其发展历程;详细论述了齿轮样板的种类、结构及特... 齿轮样板是齿轮参数量值的标准实物载体,用于将齿轮国家测量标准所复现的量值传递到各级齿轮测量仪器上,从而实现齿轮测量的准确性和一致性,保证齿轮产品质量。全面概述了齿轮样板起源及其发展历程;详细论述了齿轮样板的种类、结构及特点、齿轮样板的测量技术及装置、齿轮样板的国际比对、未来的发展与展望。齿轮样板迄今已历经九十多年发展,其种类在不断丰富、尺度不断延伸、复杂度不断简化,作为一种“有形”的实物量具,目前仍不可替代。未来随着“无形”的虚拟仿真测量技术发展,对“有形”实物样板的依赖将可以减弱,“无形”的技术将可能成为量值传递的新模式。 展开更多
关键词 齿轮 齿轮样板 齿轮测量 量值传递与溯源 国际比对 虚拟测量
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微弱光探测器光谱响应测量装置
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作者 吕亮 罗宇鹏 +2 位作者 姜晓梅 林晓峰 庞博文 《计量学报》 CSCD 北大核心 2024年第8期1089-1095,共7页
为满足光子计数类型光电探测器光谱响应度的计量需求,建立了微弱光探测器光谱响应测量装置,其特点是可在pW级单色光功率水平下实现光谱比较测量。设计了可调式亮度源,与色散相减双光栅单色仪密闭耦合后实现了6个量级的功率可调单色光输... 为满足光子计数类型光电探测器光谱响应度的计量需求,建立了微弱光探测器光谱响应测量装置,其特点是可在pW级单色光功率水平下实现光谱比较测量。设计了可调式亮度源,与色散相减双光栅单色仪密闭耦合后实现了6个量级的功率可调单色光输出,可适用于不同光子探测器的线性工作区间,波长范围覆盖330~1 100 nm。设计的密闭准直光路使系统可在正常照明环境下工作,降低了实验环境要求。以集成fA级电流放大器的标准探测器为参考,实现被测光子探测器计数率在1×10^(6)个/s量级的光谱响应度测量。基于LabView编写了专用的控制及数据采集软件,实现了自动化测量。对系统的各项计量特性进行了实验,在330~1 100 nm波段内完成了光子探测器相对光谱响应度测量,相对扩展不确定度为(2.5~3.8)%,k=2。 展开更多
关键词 光学计量 光谱响应度 光谱比较 微弱光测量 光子计数 不确定度
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煤炭码头粉尘无组织排放防治措施对比研究
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作者 洪宁宁 彭士涛 +4 位作者 苏宁 叶寅 崔继宪 刘鹏 程利 《水道港口》 2024年第3期455-460,共6页
露天堆场的粉尘无组织排放一直是干散货码头大气污染防治工作的重点和难点。苫盖和湿式除尘是我国专业化煤炭码头露天堆场粉尘无组织排放的两种主流防治措施。文章以北方某煤码头为例,基于露天堆场采用苫盖和湿式除尘措施下的粉尘无组... 露天堆场的粉尘无组织排放一直是干散货码头大气污染防治工作的重点和难点。苫盖和湿式除尘是我国专业化煤炭码头露天堆场粉尘无组织排放的两种主流防治措施。文章以北方某煤码头为例,基于露天堆场采用苫盖和湿式除尘措施下的粉尘无组织排放浓度监测数据,对两种主流粉尘防治措施的环保效益进行了对比分析。研究结果显示:采用湿式除尘措施比采用苫盖措施更适用于高周转率的专业化煤炭码头露天堆场的粉尘无组织排放的防治。 展开更多
关键词 绿色港口 专业化煤炭堆场 粉尘防治措施 环保效益对比
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公差配合与测量技术在实际应用中几种特殊情况的分析与探讨
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作者 徐奎照 刘春霞 《价值工程》 2024年第17期155-158,共4页
结合实际工作,用对比法和计算法,分析和探讨了公差配合与测量技术中,经常遇到的几种特殊情况在实际应用时,所采用的与常规不同的处理方法。可指导技术人员厘清标准和实际应用的不同之处,具有重要的应用价值和指导意义。
关键词 公差配合 测量 特殊情况 对比和计算 分析与探讨
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基于Modbus协议的湿度检定系统设计
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作者 崔学林 梁宝龙 +2 位作者 黄斌 陈亮 李伟 《电子技术应用》 2024年第5期35-40,共6页
为了提高湿度计量的工作效率和数字化安全管理水平,设计了一种基于Modbus协议的湿度检定系统。该系统依托Modbus RTU协议模式、精密露点仪数据格式和Agilent34401A数字万用表可编程仪器的标准命令协议,实现了湿度发生器自动控制,提高了... 为了提高湿度计量的工作效率和数字化安全管理水平,设计了一种基于Modbus协议的湿度检定系统。该系统依托Modbus RTU协议模式、精密露点仪数据格式和Agilent34401A数字万用表可编程仪器的标准命令协议,实现了湿度发生器自动控制,提高了检定效率和数据安全性。湿度检定系统检定结果的扩展不确定度为1.3%。采用测量仪器特性评定和传递比较法对系统测量结果进行验证,测量结果均验证通过,表明系统可进行业务化应用。 展开更多
关键词 MODBUS协议 湿度计量 不确定度 传递比较法
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水流速装置比对传递标准的评价方法研究
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作者 周书恺 刘源 +2 位作者 胡鹤鸣 刘铁军 谢代梁 《中国测试》 CAS 北大核心 2024年第3期90-96,共7页
水流速装置是各式流速仪的检定校准装置,为考察各实验室装置量值复现的准确性,可实施装置间的计量比对。拟选用两台测速原理不同的流速仪作传递标准,针对仪器的测量重复性、长期稳定性和安装条件等在传递过程中会对比对结果产生影响的... 水流速装置是各式流速仪的检定校准装置,为考察各实验室装置量值复现的准确性,可实施装置间的计量比对。拟选用两台测速原理不同的流速仪作传递标准,针对仪器的测量重复性、长期稳定性和安装条件等在传递过程中会对比对结果产生影响的因素开展实验,并完成测量结果不确定度评定。在规定的考察时间和流速范围内,两台新流速仪做相同流速点测试实验。LS1206B转子式流速仪在测试中测量重复性保持在0.1%以下,稳定性在0.5%范围内,较之于Vector性能表现更好;LS1206B的水力螺距测量不确定度在高流速下更小,其不确定度主要来源有标准装置引入的流速不确定度、测量重复性引入的不确定度和仪器安装偏角引入的不确定度;若实际安装时偏角较大,会严重影响测量结果进而影响比对结果。另一台Vector声学多普勒流速仪在良好的信噪比环境下,重复性和稳定性都在1%以内,其不确定度来源有装置引入的流速不确定度和测量重复性引入的不确定度。 展开更多
关键词 水流速装置 计量比对 传递标准 不确定度评价
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中国空间站的微波星地时频比对技术及其初步试验验证和分析
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作者 郭燕铭 高帅和 +10 位作者 潘志兵 王沛 龚学文 宋坤 周晨 张文颖 陈晓锋 白燕 高玉平 卢晓春 张首刚 《电子学报》 EI CAS CSCD 北大核心 2024年第4期1239-1249,共11页
高精度时频比对是现代科学技术的核心需求之一.然而,现有的技术受限于比对系统测量水平和链路系统误差处理算法,严重限制了时间比对性能的提升.针对这些问题,本研究搭建了基于中国空间站的高精度星地微波时频比对系统,并提出了一种基于... 高精度时频比对是现代科学技术的核心需求之一.然而,现有的技术受限于比对系统测量水平和链路系统误差处理算法,严重限制了时间比对性能的提升.针对这些问题,本研究搭建了基于中国空间站的高精度星地微波时频比对系统,并提出了一种基于双向测量的空间站-地面时频比对技术(三频模式),包括了对各项链路系统误差精细化建模新方法.通过对不同星地时频比对场景的仿真模拟发现,在配置高精度原子钟(10^(−15)~10^(−17))进行星地时频比对的场景下,经过本文算法优化后的比对长期性能仍可达与原本星地时钟相近的性能.利用中国空间站所搭载的氢钟与地面氢钟进行初步比对试验结果表明,在300 s可视弧段内的空间站-地面时间比对精度可达到10.77 ps,相应的ADEV(Allan DEViation)达到9.9921×10^(−14)@100 s,与仿真模拟结果大致吻合.本研究可为精密时频同步技术提供了新的理论依据和技术参考. 展开更多
关键词 中国空间站 原子钟 星地微波链路 时频比对 双向测量
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