期刊文献+
共找到9篇文章
< 1 >
每页显示 20 50 100
Automatic measurement of three-phase contact angles in pore throats based on digital images
1
作者 ZANG Chuanzhen WANG Lida +3 位作者 ZHOU Kaihu YU Fuwei JIANG Hanqiao LI Junjian 《Petroleum Exploration and Development》 SCIE 2023年第2期442-449,共8页
With the help of digital image processing technology, an automatic measurement method for the three-phase contact angles in the pore throats of the microfluidic model was established using the microfluidic water flood... With the help of digital image processing technology, an automatic measurement method for the three-phase contact angles in the pore throats of the microfluidic model was established using the microfluidic water flooding experiment videos as the data source. The results of the new method were verified through comparing with the manual measurement data.On this basis, the dynamic changes of the three-phase contact angles under flow conditions were clarified by the contact angles probability density curve and mean value change curve. The results show that, for water-wetting rocks, the mean value of the contact angles is acute angle during the early stage of the water flooding process, and it increases with the displacement time and becomes obtuse angle in the middle-late stage of displacement as the dominant force of oil phase gradually changes from viscous force to capillary force. The droplet flow in the remaining oil occurs in the central part of the pore throats, without three-phase contact angle. The contact angles for the porous flow and the columnar flow change slightly during the displacement and present as obtuse angles in view of mean values, which makes the remaining oil poorly movable and thus hard to be recovered. The mean value of the contact angle for the cluster flow tends to increase in the flooding process, which makes the remaining oil more difficult to be recovered. The contact angles for the membrane flow are mainly obtuse angles and reach the highest mean value in the late stage of displacement, which makes the remaining oil most difficult to be recovered. After displacement, the remaining oils under different flow regimes are just subjected to capillary force, with obtuse contact angles, and the wettability of the pore throat walls in the microfluidic model tends to be oil-wet under the action of crude oil. 展开更多
关键词 microfluidic model water flooding experiment digital image processing three-phase contact angle measure-ment method flow regime of the remaining oil
下载PDF
头穴丛刺配合蜡疗对痉挛型脑瘫患者运动功能的影响 被引量:14
2
作者 任婷 朱路文 唐强 《上海针灸杂志》 2017年第5期529-532,共4页
目的观察头穴丛刺配合蜡疗对脑瘫患者运动功能的影响。方法将符合纳入标准的痉挛型脑瘫患者40例,随机分为对照组与观察组,每组20例。对照组采用头穴丛刺长留针疗法,并给予针对痉挛型脑瘫患者的上田法及各项常规康复训练;观察组在对照组... 目的观察头穴丛刺配合蜡疗对脑瘫患者运动功能的影响。方法将符合纳入标准的痉挛型脑瘫患者40例,随机分为对照组与观察组,每组20例。对照组采用头穴丛刺长留针疗法,并给予针对痉挛型脑瘫患者的上田法及各项常规康复训练;观察组在对照组的基础上配合蜡疗。每日1次,共治疗8星期。治疗前后采用粗大运动功能量表(GMFM-88)、改良Ashworth量表评分进行运动功能评定。结果两组组内治疗前后GMFM-88评分比较,差异均具有统计学意义(P<0.05);两组治疗后GMFM-88评分比较,差异有统计学意义(P<0.05)。观察组治疗前后改良Ashworth量表评分比较,差异有统计学意义(P<0.05);对照组治疗前后改良Ashworth量表评分比较,差异无统计学意义(P>0.05);两组治疗后改良Ashworth量表评分比较,差异有统计学意义(P<0.05)。结论在常规康复训练基础上,头穴丛刺配合蜡疗对痉挛型脑瘫患者的肌张力及运动功能的恢复效果明显,有益于促进脑瘫患者的正常发育。 展开更多
关键词 脑性瘫痪 痉挛型 康复训练 运动功能 头针 丛刺 蜡疗 粗大运动功能量表 改良Ashworth量表 GROSS Motor Function measure-88
下载PDF
Iterative Learning Disturbance Observer Based Attitude Stabilization of Flexible Spacecraft Subject to Complex Disturbances and Measurement Noises 被引量:3
3
作者 Tongfu He Zhong Wu 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2021年第9期1576-1587,共12页
To realize high-precision attitude stabilization of a flexible spacecraft in the presence of complex disturbances and measurement noises,an iterative learning disturbance observer(ILDO)is presented in this paper.First... To realize high-precision attitude stabilization of a flexible spacecraft in the presence of complex disturbances and measurement noises,an iterative learning disturbance observer(ILDO)is presented in this paper.Firstly,a dynamic model of disturbance is built by augmenting the integral of the lumped disturbance as a state.Based on it,ILDO is designed by introducing iterative learning structures.Then,comparative analyses of ILDO and traditional disturbance observers are carried out in frequency domain.It demonstrates that ILDO combines the advantages of high accuracy in disturbance estimation and favorable robustness to measurement noise.After that,an ILDO based composite controller is designed to stabilize the spacecraft attitude.Finally,the effectiveness of the proposed control scheme is verified by simulations. 展开更多
关键词 Disturbance observer iterative learning measure-ment noise spacecraft attitude control
下载PDF
Environmental Radiation Measurement and Assessment of Natural Radioactivity in Soil, Water and Vegetation 被引量:1
4
作者 Nandi-Esom Chariette Ereh Meng Zhang 《Journal of Applied Mathematics and Physics》 2018年第11期2330-2337,共8页
Environmental radioactivity is produced by radioactive materials in the human environment. While some radioisotopes, such as strontium-90 (90Sr) and technetium-99 (99Tc), are only found on Earth as a result of human a... Environmental radioactivity is produced by radioactive materials in the human environment. While some radioisotopes, such as strontium-90 (90Sr) and technetium-99 (99Tc), are only found on Earth as a result of human activity, and some, like potassium-40 (40K), are only present due to natural processes, a few isotopes, e.g. tritium (3H), result from both natural processes and human activities. The concentration and location of some natural isotopes, particularly uranium-238 (238U), can be affected by human activity because of the constant exposure of Human beings to radiation caused by terrestrial, extra-terrestrial and anthropogenic radio nuclides, it is necessary to determine and estimate the activity of various radio nuclides in environmental media such as vegetation, soil, and water. In the present research, the activities of 226Ra, 232Th and 40K are measured in soil, vegetation and water samples, collected from Yangdong District, Yangxi County, and Yangjiang County of Guangdong Province, China using an HPGe based gamma spectrometry system. The measured mean activity of 226Ra, 232Th and 40K in soil samples was found to be 31.19 ± 1.2, 47.00 ± 2.30 and 589.31 ± 17.52 Bqkg-1, respectively. The measured mean activity of these radionuclides in all water samples was found to be below minimum detectable activity. The measured mean activity of 226Ra, 232Th and 40K in vegetation samples was 19.92 ± 3.09, 25.36 ± 8.11 and 4982.94 ± 85.68 Bqkg-1, respectively. No anthropogenic 137Cs was detected in these environmental samples. Mean radium equivalent activity (Raeq), external radiation hazard index (Hex), internal radiation hazard index (Hin) and absorbed dose rate (D) for the area under study were determined as 142.92 Bqkg-1, 0.38, 0.47 and 66.47 nGyh-1, respectively. The annual effective dose equivalent (AEDE) varied in the range from 0.03 to 0.12 mSvy-1. It is concluded that the surveyed area do not pose any significant radiological risk to the population and environment. 展开更多
关键词 High PURITY GERMANIUM Detector RADIUM THORIUM POTASSIUM RADIUM Equivalent Activity Radiation HAZARD Indices and Environment measure-ment
下载PDF
加气混凝土砌块墙体的质量问题及应对措施 被引量:2
5
作者 许秀凤 《广东交通职业技术学院学报》 2004年第1期49-51,共3页
加气混凝土砌块具有轻质高强、保温隔热隔音效能好等优良特性,但加气混凝土砌块墙体在建造和使用过程中会出现墙体开裂、饰面空鼓脱落等质量通病。本文通过对加气混凝土砌块的性能及施工技术特点的分析,总结了解决加气混凝土砌块墙体质... 加气混凝土砌块具有轻质高强、保温隔热隔音效能好等优良特性,但加气混凝土砌块墙体在建造和使用过程中会出现墙体开裂、饰面空鼓脱落等质量通病。本文通过对加气混凝土砌块的性能及施工技术特点的分析,总结了解决加气混凝土砌块墙体质量通病的防治措施。 展开更多
关键词 加气混凝土砌块 墙体 质量问题 粘结砂浆添加剂 施工技术 防治措施
下载PDF
Enhancing the precision of phase estimation by weak measurement and quantum measurement reversal
6
作者 贺志 姚春梅 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第11期232-237,共6页
The enhancement of the precision of phase estimation in quantum metrology is investigated by employing weak measurement (WM) and quantum measurement reversal (QMR). We derive the exact expressions of the optimal q... The enhancement of the precision of phase estimation in quantum metrology is investigated by employing weak measurement (WM) and quantum measurement reversal (QMR). We derive the exact expressions of the optimal quantum Fisher information (QFI) and success probability of phase estimation for an exactly solving model consisting of a qubit interacting with a structured reservoir. We show that the QFI can be obviously enhanced by means of the WM and QMR in different regimes. In addition, we also show that the magnitude of the decoherence involved in the WM and QMR can be a general complex number, which extends the applicable scope of the WM and QMR approach. 展开更多
关键词 precision of phase estimation quantum fisher information weak measurement quantum measure-ment reversal
下载PDF
Practical compensation for nonlinear dynamic thrust measurement system 被引量:2
7
作者 Chen Lin Chen Jie Li Jianxun 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2015年第2期418-426,共9页
The real dynamic thrust measurement system usually tends to be nonlinear due to the complex characteristics of the rig, pipes connection, etc. For a real dynamic measuring system, the nonlinearity must be eliminated b... The real dynamic thrust measurement system usually tends to be nonlinear due to the complex characteristics of the rig, pipes connection, etc. For a real dynamic measuring system, the nonlinearity must be eliminated by some adequate methods. In this paper, a nonlinear model of dynamic thrust measurement system is established by using radial basis function neural network (RBF-NN), where a novel multi-step force generator is designed to stimulate the nonlinearity of the system, and a practical compensation method for the measurement system using left inverse model is proposed. Left inverse model can be considered as a perfect dynamic compensation of the dynamic thrust measurement system, and in practice, it can be approximated by RBF-NN based on least mean square (LMS) algorithms. Different weights are set for producing the multi-step force, which is the ideal input signal of the nonlinear dynamic thrust measurement system. The validity of the compensation method depends on the engine's performance and the tolerance error 0.5%, which is commonly demanded in engineering. Results from simulations and experiments show that the practical compensation using left inverse model based on RBF-NN in dynamic thrust measuring system can yield high tracking accuracy than the conventional methods. 展开更多
关键词 Digital compensation Dynamic thrust measure-ment system Identification Left inverse model Nonlinear model Radial basis function neuralnetwork
原文传递
Multi-LED package design,fabrication and thermal analysis 被引量:1
8
作者 R.H.Poelma S.Tarashioon +3 位作者 H.W.van Zeijl S.Goldbach J.L.J.Zijl G.Q.Zhang 《Journal of Semiconductors》 EI CAS CSCD 2013年第5期54-58,共5页
An ultra-thin multi-LED package is designed, manufactured and its thermal performance is character- ized. The objective of this study is to develop an efficient thermal modelling approach for this system which can be ... An ultra-thin multi-LED package is designed, manufactured and its thermal performance is character- ized. The objective of this study is to develop an efficient thermal modelling approach for this system which can be used for optimization of the thermal-performance of future ultra-thin designs. A high-resolution thermal imaging camera and thermocouples were used to measure the temperature distribution of the multi-LED package and the LED-die temperature for different operating powers. Finally, we compare the thermal measurements with the finite element simulation results. It is concluded that the modelling approach can assist in the thermal optimization of future multi-LED package designs. 展开更多
关键词 LED PACKAGING optics molding high-resolution thermal imaging thermal modeling and measure-ments
原文传递
Cross-correlation frequency-resolved optical gating scheme based on a periodically poled lithium niobate waveguide for an optical arbitrary waveform measurement
9
作者 Chenwenji WANG Peili LI +3 位作者 Yuying GAN Di CAO Xiaozheng QIAO Chen HE 《Frontiers of Optoelectronics》 EI CSCD 2017年第1期70-79,共10页
This study proposes a novel scheme of a cross- correlation frequency-resolved optical gating (X-FROG) measurement for an optical based on the sum frequency arbitrary waveform (OAW) generation (SFG) effect of a p... This study proposes a novel scheme of a cross- correlation frequency-resolved optical gating (X-FROG) measurement for an optical based on the sum frequency arbitrary waveform (OAW) generation (SFG) effect of a periodically poled lithium niobate (PPLN) waveguide. Based on the SFG effect and combined with the principal component generalized projects algorithm on a matrix, the theory model of the scheme is established. Using Matlab, the proposed OAW measurement X-FROG scheme using the PPLN waveguide is simulated and studied. Simulation results show that a rectangular pulse is a suitable gate pulse because of its low errors. Moreover, the increased complexity of OAW and phase mismatch decrease measurement accuracy. 展开更多
关键词 optical arbitrary waveform (0AW) measure-ment periodically poled lithium niobate (PPLN) cross-correlation frequency-resolved optical gating (X-FROG)
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部