期刊文献+
共找到25,667篇文章
< 1 2 250 >
每页显示 20 50 100
Experimental Investigation of Laser Surface Hardening of AISI 4340 Steel Using Different Laser Scanning Patterns 认领
1
作者 Baha Tarchoun Abderrazak El Ouafi Ahmed Chebak 《矿物质和材料特性和工程(英文)》 2020年第2期9-26,共18页
Laser surface transformation hardening becomes one of the most modern processes used to improve fatigue and wear properties of steel surfaces. In this process, the material properties and the heating parameters are th... Laser surface transformation hardening becomes one of the most modern processes used to improve fatigue and wear properties of steel surfaces. In this process, the material properties and the heating parameters are the factors that present the most significant effects on the hardened surface attributes. The control of these factors using predictive modeling approaches to achieve desired surface properties leads to conclusive results. However, when the dimensions of the surface to be treated are larger than the cross-section of the laser beam, various laser-scanning patterns are involved. This paper presents an experimental investigation of laser surface hardening of AISI 4340 steel using different laser scanning patterns. This investigation is based on a structured experimental design using the Taguchi method and improved statistical analysis tools. Experiments are carried out using a 3 kW Nd: YAG laser source in order to evaluate the effects of the heating parameters and patterns design parameters on the physical and geometrical characteristics of the hardened surface. Laser power, scanning speed and scanning patterns (linear, sinusoidal, triangular and trochoid) are the factors used to evaluate the hardened depth and the hardened width variations and to identify the possible relationship between these factors and the hardened zone attributes. Various statistical tools such as ANOVA, correlations analysis and response surfaces are applied in order to examine the effects of the experimental factors on the hardened surface characteristics. The results reveal that the scanning patterns do not modify the nature of the laser parameters’ effects on the hardened depth and the hardened width. But they can accentuate or reduce these effects depending on the type of the considered pattern. The results show also that the sinusoidal and the triangular patterns are relevant when a maximum hardened width with an acceptable hardened depth is desired. 展开更多
关键词 LASER Surface HARDENING Process Experimental Investigation LASER Scanning PATTERNS AISI 4340 STEEL Hardness Profile Hardened Depth Hardened WIDTH Design of Experiment Analysis of Variance
在线阅读 免费下载
Estimation of Curie Point Depth (CPD) across the Pan African Belt in Northern Cameroon from Aeromagnetic Data 认领
2
作者 Jean Daniel Ngoh Théophile Ndougsa Mbarga +2 位作者 Kevin Mickus Yara Tarek Tabod Charles Tabod 《地震研究(英文)》 2020年第3期217-239,共23页
The depth to the Curie isothermal point (CPD) was estimated using aeromagnetic data from northern Cameroon. The CPD was estimated using a two-dimensional power density spectral analysis of nineteen 30 × 30 km blo... The depth to the Curie isothermal point (CPD) was estimated using aeromagnetic data from northern Cameroon. The CPD was estimated using a two-dimensional power density spectral analysis of nineteen 30 × 30 km blocks over a series of Neoproterozoic lithologies associated with the Pan African orogeny. The results show that there are two main regions characterized by the CPD analysis: 1) Shallow depths (~6.37 - 10.09 km) which are located in several regions including the northern portions of the study area (toward the regions of Hina Marbak, Gawel and northern Moutouroua), the southeast (Kaele region), the south (Guider) and the southwest (Mayo Oulo), and 2) deeper depths (~10.68 - 13.72 km) are located in the northeast (Mindif) and southwest (southern Moutouroua, Guider and Bossoum). The shallow depths can be related to two tectonic regimes: 1) the West-Central African Rift System with northeast-trending strike-slip faults emanating from the Gulf of Guinea and 2) the Cameroon Volcanic Line. However, the ultimate source of these shallow regions is interpreted to be related to the Cameroon Volcanic Line based on low seismic velocities imaged by recent broadband seismic studies which are concentrated along the northeast-trending strike-slip faults. An additional finding using the CPD depths, a Curie isothermal temperature of 580&#176C and a one-dimensional heat flow model, was heat-flow values ranging from 105.68 to 227.63 mW/m2, which are above average global heat flow values and are therefore indicative of potential geothermal resources. 展开更多
关键词 Magnetic ANOMALY Spectral Analysis CURIE Point DEPTH GEOTHERMAL Gradi-ent Heat Flow
在线阅读 免费下载
Quantitative Interpretation of Gravity Anomalies in the Kribi-Campo Sedimentary Basin (South Cameroon) Based on Spectral Analysis and 2.5D Modelling: Structural Implications 认领
3
作者 Kue Petou Rokis Malquaire Owona Angue Marie Louise Clotilde +5 位作者 Njingti Nfor Eloundou Essama Lionel Mioumnde Arthur Paterne Kue Negham Martine Clémence Manguelle-Dicoum Eliezer Weiqi Song 《地震研究(英文)》 2020年第3期240-254,共15页
Ground gravity survey was recently carried out in the Lolabe-Campo area, which constitutes the southern onshore portion of the Kribi-Campo sub-basin in South Cameroon. The obtained gravity data were processed and inte... Ground gravity survey was recently carried out in the Lolabe-Campo area, which constitutes the southern onshore portion of the Kribi-Campo sub-basin in South Cameroon. The obtained gravity data were processed and interpreted in order to elucidate the subsurface geology of the area in which preliminary studies highlighted the presence of an intrusive igneous body. In order to determine the nature and the characteristics of this body, spectral analysis, ideal body solution and 2.5D modelling methods were applied to the gravity data. The results suggest that the emplacement, breaking up and separation of the intrusive igneous body were the outcome of two tectonic events corresponding to an upward vertical translational tectonic movement followed by an anticlockwise rotational faulting tectonic movement. From a density contrast of 0.13 g&#183cm&#453, the two isolated bodies have an estimated density of 2.80 g&#183cm&#453 which is comparatively higher than the average density of 2.67 g&#183cm&#453 of the autochthonous rocks. These two blocks are completely surrounded by both sedimentary and metamorphic formations and are confined between the depths of 0.6 km and 3.5 km. The highly dense nature of the rocks and their location around the Atlantic Ocean led to the conclusion that the two intrusive bodies are composed principally of gabbro. The disposition and shape of the open zone resulting from the separation of the blocks are suggestive of a trap for the accumulation of hydrocarbons and mineral resources. 展开更多
关键词 Spectral Analysis IDEAL Body 2.5D MODELLING Formation DEPTH INTRUSIVE BLOCKS
在线阅读 免费下载
Using the Latin Square Design Model in the Prioritzation of Network Security Threats: A Quantitative Study 认领
4
作者 Rodney Alexander 《信息安全(英文)》 2020年第2期92-102,共11页
Society is becoming increasingly dependent on cyberspace for both business and pleasure. Cyber attackers continue to attack organizational computer networks, as those same computer networks become increasing critical ... Society is becoming increasingly dependent on cyberspace for both business and pleasure. Cyber attackers continue to attack organizational computer networks, as those same computer networks become increasing critical to organizational business process. Strategic planning and managing IT security risks play an important role in the business and government planning process. Deploying defense in depth security measures can ensure that organizations continue to function in times of crisis. This quantitative study explores whether the Latin Square Design (LSD) model can be effectively applied to the prioritization of cybersecurity threats and to the linking of information assurance defense in-depth measures to those threats. The methods used in this study consisted of scanning 10 Cybersecurity Websites such as the Department of Homeland Security US CERT (United States-Computer Emergency Readiness Team [1]) and the SANS Institute (SysAdmin, Audit, Network and Security [2]) using the Likert Scale Model for the Website’s top ten list of cyber threats facing organizations and the network defense in depth measures to fight those threats. A comparison of each cybersecurity threats was then made using LSD to determine whether the Likert scale and the LSD model could be effectively applied to prioritize information assurance measures to protect organizational computing devices. The findings of the research reject the H0 null hypothesis that LSD does not affect the relationship between the ranking of 10 Cybersecurity websites top ten cybersecurity threats dependent variables and the independent variables of defense in depth measures used in protecting organizational devices against cyber-attacks. 展开更多
关键词 INFORMATION ASSURANCE LATIN Square Design Model DEFENSE in DEPTH INFORMATION Technology Network Security CYBERSECURITY
在线阅读 免费下载
辐射变暗和透明度降低共同加剧湖泊水下变黑 认领
5
作者 张运林 秦伯强 +11 位作者 施坤 张毅博 邓建明 Martin Wild Lin Li 周永强 姚晓龙 刘淼 朱广伟 张路 Binhe Gu Justin D.Brookes 《科学通报:英文版》 SCIE EI CAS CSCD 2020年第19期1675-1684,M0004,共11页
人类活动和气候变化造成到达地表太阳辐射降低(即辐射变暗)和水体透明度下降,两者共同作用深刻影响到水生生态系统水下光环境.全国116个太阳辐射观测站和839个日照时数观测站长期观测数据显示,2000年之后年均地表太阳辐射和日照时数比2... 人类活动和气候变化造成到达地表太阳辐射降低(即辐射变暗)和水体透明度下降,两者共同作用深刻影响到水生生态系统水下光环境.全国116个太阳辐射观测站和839个日照时数观测站长期观测数据显示,2000年之后年均地表太阳辐射和日照时数比20世纪60年代分别下降了5.8%和7.9%,呈现显著下降趋势.与此同时,20世纪80年代和2006~2010年两次全国湖泊调查和历史文献数据分析发现,170个湖泊透明度平均值由1995年之前的1.80±2.19 m下降到2005年之后的1.28±1.82 m,遥感反演发现641个面积大于10 km2的湖泊透明度平均值由1985~1990年的1.26±0.62 m降低到2005~2010年的1.14±0.66 m.辐射变暗和透明度降低共同造成全国湖泊平均真光层深度范围内可利用的光合有效辐射量降低10%左右,并且透明度降低对湖泊水下光合有效辐射降低的贡献超过80%.文献综合分析进一步显示,全球湖库、海湾和近海水体均普遍存在透明度下降,水下变暗甚至变黑的事实,其势必深刻影响到水生生态系统各种物理、化学和生物过程以及生物多样性、生态系统服务功能和服务价值. 展开更多
关键词 Radiation dimming Underwater darkening Secchi disk depth Remote sensing Aquatic ecosystems
Depth Estimation of Geothermal Heat Structures by Euler Deconvolution of Gravity Data at Eburru Area, Kenya 认领
6
作者 Erick Rayora Nyakundi John Githiri Maurice K’Orowe 《地球科学和环境保护期刊(英文)》 2020年第3期148-158,共11页
Gravity survey was done at the Eburru area to estimate the source depth locations and delineate the fault boundaries using 3D Euler deconvolution. Gravity data was collected using CG-5 gravimeter. Gravity data reducti... Gravity survey was done at the Eburru area to estimate the source depth locations and delineate the fault boundaries using 3D Euler deconvolution. Gravity data was collected using CG-5 gravimeter. Gravity data reductions were done by applying drift correction, latitude correction, free air correction, Bouguer correction and terrain correction to the observed raw data to obtain complete bouguer anomaly (CBA). The CBA data was transferred to Oasis montaj software for Euler deconvolution processing. The 3D Euler deconvolution was carried out to determine and estimate the depth of the density bodies. Euler deconvolution locates the gravity anomaly source and estimates its depth from the gravity observation level. Euler deconvolution was preferred to other filtering methods in this study as solutions are only determined over identified analytic signal peaks, the window size varies according to anomaly size and the final solution involves only a few more precise depth estimates. The Euler deconvolution was performed using structural indices of 0.5, 1.0 and 2.0. Results from this analysis indicated that the CBA values in this study area range from gravity values of -272 mGal to -286 mGal and residual Bouguer anomaly amplitude range between -3 mGal and 3.4 mGal. The 0.5, 1.0 and 2.0 structural indices generated five solutions at depth range of 433 m - 2269 m, 801 m - 1433 m and 1170 m - 2246 m respectively occurring almost at the same locations on gravity highs. The deep structures were observed to occur in the northern part of the study area, and interpreted to be dense intruding masses likely to be trapped by the overlying cap rock at these depths. These could be geothermal heat sources that can be exploited to generate geothermal energy. 展开更多
关键词 EULER DECONVOLUTION SOURCE Depth Structural Index Gravity Data Bouguer ANOMALY GEOTHERMAL Heat SOURCE
在线阅读 免费下载
Estimation of particle depth from two defocused images using the Fourier transform 认领
7
作者 Wu Zhou Xu Luo +2 位作者 Benting Chen Yukun Zhang Xiaoshu Cai 《颗粒学报:英文版》 SCIE EI CAS CSCD 2020年第2期48-54,共7页
Depth from defocus is one technology for depth estimation.We estimate particle depth information from two defocused images captured simultaneously by two coaxial cameras with different imaging distances.The images are... Depth from defocus is one technology for depth estimation.We estimate particle depth information from two defocused images captured simultaneously by two coaxial cameras with different imaging distances.The images are processed with the Fourier transform to obtain the characteristic parameter(i.e.,the standard deviation of the relative blur kernel of these two defocused images).First,we theoretically analyze the functional relationship between the object depth and the standard deviation or variation of the relative blur kernel.Then,we verify the relationship experimentally.We analyze the influence of particle size,window size and image noise on the calibration curves using both numerical simulations and experiments.We obtain the depth range and accuracy of this measurement system experimentally.For the verification experiments,we use a sample of glass microbeads and the irregularly-shaped dust particles on a microscope slide.Both of these experiments present a suitable depth measurement result.Finally,we apply the measuring system to the depth estimation of drops from a small anti-fogging spray.The results show that our system and image processing algorithm are robust for different types of particles,facilitating the in-line three-dimensional positioning of particles. 展开更多
关键词 Depth from two defocused images Fourier transform Standard deviation of relative blur kernel Drops depth measurement Sensitivity and accuracy analysis
High sensitivity conductivity-temperature-depth sensing based on an optical microfiber coupler combined fiber loop 认领
8
作者 曹亮 于洋 +3 位作者 肖民 杨俊波 张学亮 孟洲 《中国光学快报:英文版》 SCIE EI CAS CSCD 2020年第1期34-39,共6页
In order to meet the practical needs of all-fiber conductivity-temperature-depth sensors with high sensitivity,compact structure,and easy packaging,this Letter uses a microfiber coupler combined with fiber loop(MCFL)r... In order to meet the practical needs of all-fiber conductivity-temperature-depth sensors with high sensitivity,compact structure,and easy packaging,this Letter uses a microfiber coupler combined with fiber loop(MCFL)reflective photonic device to conduct salinity,temperature,and deep sensing experiments.These MCFLs’dynamic range and resolution of salinity,temperature,and depth can meet the requirements of actual marine environment monitoring.This structure opens up a new design idea for the practical research of microfiber coupler-based marine environmental parameter sensors. 展开更多
关键词 microfiber coupler(MC) FIBER LOOP salinity TEMPERATURE and DEPTH SENSING cross sensitivity conductivity-temperature-depth measurement system
降雨量、土壤蓄水量对流动沙地土壤水分深层渗漏的影响 认领
9
作者 吴丽丽 刘丹一 +4 位作者 杨文斌 王涛 李卫 冯金超 冯伟 《中国沙漠》 CSCD 北大核心 2020年第3期210-218,共9页
土壤水分深层渗漏是陆地近地层水分循环的重要环节。利用土壤水分深层渗漏记录仪对毛乌素沙地典型流动沙丘不同深度土层的土壤渗漏水量连续进行两年定点监测。结果表明:(1)2016年生长季(4月1日至10月31日)降水量为2017年的1.93倍,但50、... 土壤水分深层渗漏是陆地近地层水分循环的重要环节。利用土壤水分深层渗漏记录仪对毛乌素沙地典型流动沙丘不同深度土层的土壤渗漏水量连续进行两年定点监测。结果表明:(1)2016年生长季(4月1日至10月31日)降水量为2017年的1.93倍,但50、100、200 cm沙层的渗漏水量分别是2017年同期的4.53、5.53、5.22倍。同时,渗漏水量与降雨量及土壤蓄水量的波峰较一致。(2)强降雨对深层渗漏水量的影响较大,土壤蓄水量的变化也与深层渗漏水量密切相关;降雨量较小时,土壤蓄水量与深层渗漏水量之间的关系更为密切。在连续降雨过程中,越往深处,渗漏的产生通常是多次降雨过程累积的结果,将土壤蓄水量作为中间变量,能更好地分析土壤深层渗漏过程。(3)当天蓄水量与次日渗漏水量的相关系数较高,土层越深,深层渗漏水量与土壤蓄水量的相关系数增加,二者之间的线性拟合的R~2也相应增加。 展开更多
关键词 降雨量 土壤蓄水量 渗漏水量 深度 流动沙地
T-S Fuzzy Model-Based Depth Control of Underwater Vehicles 认领
10
作者 钱缘 冯正平 +1 位作者 毕安元 刘伟奇 《上海交通大学学报:英文版》 EI 2020年第3期315-324,共10页
A T-S fuzzy model with two rules is established to exactly describe the nonlinear uncertain heave dynamics of underwater vehicles with bounded heave speed.A single linear-matrix-inequality-based (LMI-based) state feed... A T-S fuzzy model with two rules is established to exactly describe the nonlinear uncertain heave dynamics of underwater vehicles with bounded heave speed.A single linear-matrix-inequality-based (LMI-based) state feedback controller is then synthesized to guarantee the global stability of the depth control system.Simulation results verify the effectiveness of the proposed approach in comparison with linear-quadratic regulator (LQR) method.Nonlinear disturbance observer is appended to the system when the underwater vehicles are affected by the gravity-buoyancy imbalance.The two-stage control method is effective to stabilize an uncertain system with both parameter uncertainties and external disturbances. 展开更多
关键词 underwater vehicles UNCERTAINTY depth control T-S fuzzy model
A method for calibrating the confocal volume of a confocal three-dimensional micro-x-ray fluorescence setup 认领
11
作者 周鹏 马欣然 +2 位作者 张爽 孙天希 刘志国 《中国物理B:英文版》 SCIE EI CAS CSCD 2020年第2期190-195,共6页
The measurement of the confocal volume of a confocal three-dimensional micro-x-ray fluorescence(3D-XRF)setup is a key step in the field of confocal 3D-XRF analysis.With the development of x-ray facilities and optical ... The measurement of the confocal volume of a confocal three-dimensional micro-x-ray fluorescence(3D-XRF)setup is a key step in the field of confocal 3D-XRF analysis.With the development of x-ray facilities and optical devices,3D-XRF analysis with a micro confocal volume will create a great potential for 2D and 3D microstructural analysis and accurate quantitative analysis.However,the classic measurement method of scanning metal foils of a certain thickness leads to inaccuracy.A method for calibrating the confocal volume is proposed in this paper.The new method is based on the basic content of the textbook,and the theoretical results and the feasibility are given in detail for the 3D-XRF mono-chromatic x-ray condition and the poly-chromatic x-ray condition.We obtain a set of experimental confirmation using the poly-chromatic x-ray tube in the laboratory.It is proved that the sensitivity factor of the 3D-XRF can be directly and accurately obtained in a real calibration process. 展开更多
关键词 THREE-DIMENSIONAL micro-x-ray fluorescence(3D-XRF) depth analysis CONFOCAL VOLUME probe calibrating
Geodetic slip rate and locking depth of east Semangko Fault derived from GPS measurement 认领
12
作者 Satrio Muhammad Alif Erlangga Ibrahim Fattah Munawar Kholil 《大地测量与地球动力学:英文版》 2020年第3期222-228,共7页
65 km Semangko Fault is part of southern segments of Sumatran Fault Zone(SFZ)which is complex corresponds to the transition from the strike-slip regime of the SFZ to the normal faulting tectonics of the Sunda Strait.T... 65 km Semangko Fault is part of southern segments of Sumatran Fault Zone(SFZ)which is complex corresponds to the transition from the strike-slip regime of the SFZ to the normal faulting tectonics of the Sunda Strait.The recent publication showed branches of Semangko Fault:West Semangko Fault(WSF)and East Semangko Fault(ESF).This study estimated geodetic slip rate and locking depth of ESF using Global Positioning System(GPS)time series data from 2007 to 2019 from all available GPS sites.GPS velocities refer to Sundaland Plate were used to estimate the fault parameters of the WSF and ESF simultaneously.Non-uniformity of velocity direction shows the complexities of Semangko Fault possibly caused by the contribution of all faults around ESF.An ESF geodetic slip rate,which is 12.5±2 mm/yr was lower than WSF,which is 16.5±2 mm/yr.It is consistent with the rigid block nature of the SFZ system as northern segment slip rates have similar value.Small slip rates are possibly leading to lower generated seismic moment than the major segment of SFZ. 展开更多
关键词 Sumatran fault zone Semangko fault GPS Velocity Slip rate Locking depth
基于有限单元法的闸基防渗墙防渗效果分析 认领
13
作者 刘健 付成华 +2 位作者 王兴华 穆宵枭 刘庆彬 《人民珠江》 2020年第3期54-58,共5页
闸坝地基渗漏已成为坝基防渗设施老化所表现的重要问题之一。当渗流量危害到闸基安全时,再进行后期闸基防渗处理的难度就非常大,所以在设计阶段应当充分考虑防渗设施的设置及其效果。以四川广元昭化水电站为例,采用有限单元法建立闸基... 闸坝地基渗漏已成为坝基防渗设施老化所表现的重要问题之一。当渗流量危害到闸基安全时,再进行后期闸基防渗处理的难度就非常大,所以在设计阶段应当充分考虑防渗设施的设置及其效果。以四川广元昭化水电站为例,采用有限单元法建立闸基渗流计算模型,计算分析闸基前置防渗墙在深度、厚度变化时闸基渗流量和渗流坡降的变化规律,评价不同尺寸情况下防渗墙的防渗效果,分析结果可用于指导闸基防渗措施设计,也可为类似闸基防渗措施选取提供参考。 展开更多
关键词 闸基 防渗墙 防渗效果 厚度 深度
在线阅读 免费下载
伴白内障的青光眼手术与激光治疗的效果比较 认领
14
作者 昝晓宁 祁颖 《中华眼外伤职业眼病杂志》 2020年第3期193-199,共7页
目的比较超声乳化术与激光周边虹膜切开术(LPI)两者治疗伴白内障的原发性闭角型青光眼(PACG)手术效果。方法回顾性分析郑州大学第一附属医院2018年5月至2019年6月伴白内障的PACG 51例(59眼)的临床资料,患者分为两组:超乳组,28眼,行超声... 目的比较超声乳化术与激光周边虹膜切开术(LPI)两者治疗伴白内障的原发性闭角型青光眼(PACG)手术效果。方法回顾性分析郑州大学第一附属医院2018年5月至2019年6月伴白内障的PACG 51例(59眼)的临床资料,患者分为两组:超乳组,28眼,行超声乳化术;激光组,31眼行LPI。术后观察眼压、视力及前房参数等。结果术前超乳组与激光组眼压为(23.32±3.31)mmHg和(22.79±2.89)mmHg(1 mmHg=0.133 kPa),差异无统计学意义(t=0.658,P=0.513)。两组术后各时间点眼压均较术前下降,术后1个月和3个月超乳组眼压均低于激光组,差异有统计学意义(t=3.648,6.542;P=0.001,0.000)。术前超乳组最佳矫正视力(logMAR)为0.35±0.10,与激光组的视力0.33±0.09相比,差异无统计学意义(t=0.855,P=0.396)。术后3个月超乳组视力较术前明显提高(t=11.829,P=0.000),激光组无明显变化(t=-1.710,P=0.098)。术后3个月,超乳组中央前房深度(t=-30.553,P=0.000)、周边前房深度(上、下、鼻及颞侧)(t=-18.911,-21.389,-15.638,-20.983;均P=0.000)、前房容积(t=-19.205,P=0.000)及前房角(t=-16.693,P=0.000)均较术前增加,且前房角全周开放。而激光组前房各指标改善均不如超乳组,术后仍有8眼(25.8%)前房角关闭超过180°。结论与LPI相比,超声乳化术治疗伴白内障的PACG可降低眼压、提高视力,明显改善前房参数。 展开更多
关键词 青光眼 闭角型 原发性 白内障 超声乳化术 虹膜切开术 周边 激光 深度 前房
基于煤层瓦斯含量直接测定方法的煤样尺度效应研究 认领
15
作者 魏培瑾 《能源与节能》 2020年第7期22-24,110,共4页
不同粒度的煤粒瓦斯解吸扩散规律并不相同,在工程现场应用中快速准确地测定出瓦斯含量,对于预测煤与瓦斯突出危险性具有非常重要的意义。为了研究粒度对瓦斯含量测定的影响,以焦作矿区A矿16041工作面为试验地点,采用DGC型瓦斯含量直接... 不同粒度的煤粒瓦斯解吸扩散规律并不相同,在工程现场应用中快速准确地测定出瓦斯含量,对于预测煤与瓦斯突出危险性具有非常重要的意义。为了研究粒度对瓦斯含量测定的影响,以焦作矿区A矿16041工作面为试验地点,采用DGC型瓦斯含量直接测定装置测定了不同深度的煤样损失瓦斯含量、常压解吸瓦斯含量和粉碎解吸瓦斯含量,分析各个粒度对瓦斯含量的影响,得出现场瓦斯含量测定的最佳采样粒度范围。 展开更多
关键词 瓦斯含量 粒度 深度
在线阅读 下载PDF
短空间二维傅里叶变换对铝板的损伤定量研究 认领
16
作者 常俊杰 万陶磊 钟海鹰 《电子测量与仪器学报》 CSCD 北大核心 2020年第6期102-108,共7页
针对Lamb波对铝板损伤定量难的问题,使用短空间二维傅里叶变换的方法对其进行了研究。首先,使用空气耦合超声在铝板中激励Lamb波并进行线性扫查获取其时间-空间波场信号;然后,对信号进行短空间二维傅里叶变换获取扫查区域的Lamb波空间-... 针对Lamb波对铝板损伤定量难的问题,使用短空间二维傅里叶变换的方法对其进行了研究。首先,使用空气耦合超声在铝板中激励Lamb波并进行线性扫查获取其时间-空间波场信号;然后,对信号进行短空间二维傅里叶变换获取扫查区域的Lamb波空间-波数曲线,并从中得到损伤的位置、长度和深度信息;最后,根据相速度-频厚积曲线反推出损伤的深度。结果表明,所提方法能够同时对扫查区域的板厚以及损伤的位置、长度和深度进行评估。其中,板厚定量误差最大为5.50%,损伤长度和深度的定量误差最大分别为6.00%和6.67%。 展开更多
关键词 短空间傅里叶变换 LAMB波 空气耦合超声 深度 定量 定位
Possibilities of urban flood reduction through distributed-scale rainwater harvesting 认领
17
作者 Aysha Akter Ahad Hasan Tanim MdKamrul Islam 《水科学与水工程:英文版》 EI CAS CSCD 2020年第2期95-105,共11页
Urban flooding in Chittagong City usually occurs during the monsoon season and a rainwater harvesting(RWH)system can be used as a remedial measure.This study examines the feasibility of rain barrel RWH system at a dis... Urban flooding in Chittagong City usually occurs during the monsoon season and a rainwater harvesting(RWH)system can be used as a remedial measure.This study examines the feasibility of rain barrel RWH system at a distributed scale within an urbanized area located in the northwestern part of Chittagong City that experiences flash flooding on a regular basis.For flood modeling,the storm water management model(SWMM)was employed with rain barrel low-impact development(LID)as a flood reduction measure.The Hydrologic Engineering Center's River Analysis System(HEC-RAS)inundation model was coupled with SWMM to observe the detailed and spatial extent of flood reduction.Compared to SWMM simulated floods,the simulated inundation depth using remote sensing data and the HEC-RAS showed a reasonable match,i.e.,the correlation coefficients were found to be 0.70 and 0.98,respectively.Finally,using LID,i.e.,RWH,a reduction of 28.66%could be achieved for reducing flood extent.Moreover,the study showed that 10%e60%imperviousness of the subcatchment area can yield a monthly RWH potential of 0.04e0.45 m3 from a square meter of rooftop area.The model can be used for necessary decision making for flood reduction and to establish a distributed RWH system in the study area. 展开更多
关键词 Low-impact development(LID) SWMM HEC-RAS Remote sensing Urban flooding Inundation depth
在线阅读 下载PDF
山西地震带北段与张家口--渤海地震带不同深度CO2和Rn气体通量的差异性 认领
18
作者 赵红坤 王万丽 +3 位作者 周晓成 石宏宇 孙玉涛 刘永梅 《地震地磁观测与研究》 2020年第2期113-122,共10页
2014年在山西地震带北段和张家口-渤海地震带布设35个测量剖面,测量土壤气CO2、Rn浓度及深度20 cm、1 m的CO2和Rn通量。测量结果表明:(1)CO2、Rn浓度与深度20 cm、1 m的CO2、Rn通量的平均值和最大值变化趋势大致相同,均呈自西向东的增... 2014年在山西地震带北段和张家口-渤海地震带布设35个测量剖面,测量土壤气CO2、Rn浓度及深度20 cm、1 m的CO2和Rn通量。测量结果表明:(1)CO2、Rn浓度与深度20 cm、1 m的CO2、Rn通量的平均值和最大值变化趋势大致相同,均呈自西向东的增大趋势;(2)深度20 cm、1 m的CO2和Rn通量相关性均不明显,但1 m深的CO2、Rn通量明显较高;(3)CO2和Rn浓度、通量变化主要与区域复杂的地震活动性和断层活动性有关,主要受到地表化学成分和区域岩石地球化学影响。 展开更多
关键词 土壤气 CO2 Rn 深度 通量 山西地震带和张-渤地震带
在线阅读 下载PDF
不同直径钢筋、不同埋深的雷达图像试验研究 认领
19
作者 刘金龙 陆伟东 +1 位作者 袁小军 浦琛琛 《四川建筑科学研究》 2020年第1期8-14,共7页
介绍了雷达技术的应用原理,制作了不同直径钢筋、不同埋深的混凝土试件,得到了钢筋的雷达图像典型特征,边缘检测结合腐蚀、膨胀快速提取了钢筋的边缘骨架曲线。制作了不同直径、不同埋深的6个泡沫试件,并进行了雷达图像的比对试验。试... 介绍了雷达技术的应用原理,制作了不同直径钢筋、不同埋深的混凝土试件,得到了钢筋的雷达图像典型特征,边缘检测结合腐蚀、膨胀快速提取了钢筋的边缘骨架曲线。制作了不同直径、不同埋深的6个泡沫试件,并进行了雷达图像的比对试验。试验结果表明:相同埋深、不同直径钢筋的雷达图像非常相似,所成的双曲线大小和形状很接近;相同直径钢筋、不同埋深的雷达图像均不同,埋深对钢筋所成的双曲线图像影响较大。研究成果为解决不同直径钢筋的探测提供了数据支撑。 展开更多
关键词 雷达 雷达图像 钢筋 直径 埋深 试验研究
在线阅读 免费下载
The focal depths of the 2008 Panzhihua earthquake sequence and the stress field in the source region 认领
20
作者 Yan LUO Li ZHAO Jianhui TIAN 《中国科学:地球科学英文版》 SCIE EI CAS CSCD 2020年第3期439-451,共13页
Focal depths of the 2008 Ms6.1 Panzhihua earthquake sequence and tectonic stress field in the source area are investigated.Source depths of 24 earthquakes in Panzhihua earthquake sequence with a magnitude M≥3.0 were ... Focal depths of the 2008 Ms6.1 Panzhihua earthquake sequence and tectonic stress field in the source area are investigated.Source depths of 24 earthquakes in Panzhihua earthquake sequence with a magnitude M≥3.0 were determined using the seismic depth phase sPL;additionally,the focal depths of 232 earthquakes were measured by fitting the threecomponent waveforms of the P and S waves.The source depth of the main shock is~12 km.The majority of the aftershocks with magnitude M≥3.0 occurred in the brittle upper crust at the depths range of 12-18 km.Further,the Source mechanisms of the 232events around the Panzhihua earthquake source area were determined,and the results show that the earthquakes have predominantly strike-slip mechanisms in the Dianzhong Block,but display complexity of the focal mechanisms outside and near the boundary of the Dianzhong block.The 232 earthquake mechanisms from this study are combined with the solutions from the Global Centroid Moment Tensor (GCMT) catalog to derive 2D stress field.The inversion results show that the Dianzhong block is predominantly under a strike slip faulting regime and the direction of the maximum principal compressionσ1 is northwestsoutheast (NW-SE)-trending.The distribution is coincide with GPS velocity field.However,orientations of principal stress axes as well as the faulting types change outside and near the Dianzhong block.The results show that the tectonic stress field in the study area is predominantly controlled by the southeast (SE)-trending horizontal movement and clockwise rotation of the Dianzhong block as a result of the eastward movement of eastern Tibetan meeting the old and rigid South China block (SCB).The Panzhihua earthquake ruptured at~12 km depth where the tectonic stress regime is under the SE-direction horizontal compression and the NE-direction horizontal extension. 展开更多
关键词 Panzhihua earthquake sequence DEPTH phase FOCAL mechanism solution TECTONIC stress field
上一页 1 2 250 下一页 到第
使用帮助 返回顶部 意见反馈