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Spectrum Occupancy Measurement and Analysis 被引量:1
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作者 Tian Fang 1 , Feng Zhiyong 1 , Chen Xing 2 (1 . Beijing University of Posts and Telecommunications , Beijing 100876 , P . R . China 2 . Research Institution of China Mobile Communications Corporation , Beijing 100053 , P . R . China ) 《ZTE Communications》 2009年第2期16-20,共5页
This paper analyzes current spectrum utilization from all aspects based on related methods of spectrum measurement. The measurement results show that some spectrum resources are not used effectively due to current fix... This paper analyzes current spectrum utilization from all aspects based on related methods of spectrum measurement. The measurement results show that some spectrum resources are not used effectively due to current fixed spectrum allocation policy, and the spectrum occupancy varies dramatically in terms of time and space. These results provide basis for the development of next generation wireless communication technologies such as Cognitive Radio (CR). 展开更多
关键词 Spectrum Occupancy measurement and analysis FIGURE RADIO
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Mechanical Analysis and Measurements of a Multicomponent NbTi/Cu Superconducting Magnets Structure for the Fully Superconducting Electron Cyclotron Resonance Ion Source 被引量:1
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作者 关明智 胡强 +6 位作者 高配峰 王省哲 杨通军 吴巍 辛灿杰 吴北民 马力祯 《Chinese Physics Letters》 SCIE CAS CSCD 2016年第5期135-139,共5页
A fully superconducting electron cyclotron resonance (ECR) ion source (SECRAL ID is currently being built in the Institute of Modern Physics, Chinese Academy of Sciences. Its key components are three superconductin... A fully superconducting electron cyclotron resonance (ECR) ion source (SECRAL ID is currently being built in the Institute of Modern Physics, Chinese Academy of Sciences. Its key components are three superconducting solenoids (Nb-Ti/Cu) and six superconducting sextupoles (Nb-Ti/Cu). Different from the conventional supercon- ducting ECR magnetic structure, the SEC17AL Ⅱ includes three superconducting solenoid coils' that are located inside the superconducting sextupoles. The SECRAL Ⅱ can significantly reduce the interaction forces between the sextupole and the solenoids, and the magnets can also be more compact in size. For this multi-component SECRAL Ⅱ generating its self field of -8 T and being often exposed to the high self field, the mechanical analysis has become the main issue to keep their stress at 〈200 MPa on coils. The analytical and experimental results in mechanics are presented in the SECRAL Ⅱ structure. To improve the accuracy and efficiency of analysis, according to the composite rule of micromechanics, the equivalent uniform windings are used to simulate the epoxy-impregnated Nb-Ti/Cu coils. In addition, using low temperature strain gauges and a wireless fast strain acquisition system, a fundamental experiment on the based on our analysis, the stresses and deformations optimized. strains developments of a sextupole is reported. Finally, for its assembly of each SECRAL Ⅱ coil will be further 展开更多
关键词 of on IS as NBTI Mechanical analysis and measurements of a Multicomponent NbTi/Cu Superconducting Magnets Structure for the Fully Superconducting Electron Cyclotron Resonance Ion Source in for Cu
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Analysis of differences between anatomic and CT measurements for anterior axial pedicle screw placement
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作者 郑轶Postgraduate School Southern Med Univ 《外科研究与新技术》 2011年第2期85-85,共1页
Objective To explore the differences between anatomic and CT measurements for anterior transoral axial pedicle screw placement. Methods C2 vertebrae of 60 adult spines were measured anatomically,while 20 adult spine v... Objective To explore the differences between anatomic and CT measurements for anterior transoral axial pedicle screw placement. Methods C2 vertebrae of 60 adult spines were measured anatomically,while 20 adult spine vertebrae were 展开更多
关键词 CT analysis of differences between anatomic and CT measurements for anterior axial pedicle screw placement
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Effect of building energy efficiency standards on carbon emission efficiency in commercial buildings
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作者 Xia Wang Qi Ye +1 位作者 Yan Du Mao Zhou 《Chinese Journal of Population,Resources and Environment》 2024年第3期250-257,共8页
The building sector plays a crucial role in the worldwide shift toward achieving net-zero emissions.Building energy efficiency standards(BEESs)are highly effective policies for reducing carbon emissions.Therefore,expl... The building sector plays a crucial role in the worldwide shift toward achieving net-zero emissions.Building energy efficiency standards(BEESs)are highly effective policies for reducing carbon emissions.Therefore,exploring the provincial variations in carbon emission efficiency(CEE)in the building sector and identifying the effect of BEESs on CEE is crucial.This study focuses on commercial buildings in China and applies a difference in differences model to evaluate the impact of BEESs on the CEE of commercial buildings.The slacks-based measure–data envelopment analysis model is employed to assess the CEE of commercial buildings in 30 Chinese provinces from 2000 to 2019.Furthermore,heterogeneous tests are used to explore how climate characteristics and economic conditions affect the efficiency of BEESs.The results indicate that BEESs positively influence the CEE of commercial buildings.Specifically,a 1%increase in the intensity of BEESs causes a 0.1484%increase in the CEE of commercial buildings.Moreover,the impact of BEESs is particularly pronounced in the southern and western provinces.This study provides valuable scientific evidence for governments to enhance BEESs implementation. 展开更多
关键词 Commercial buildings Carbon emissions efficiency Building energy efficiency standards Slack-based measure–data development analysis Difference in differences
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Analysis on the Problems in Start-up and Debugging of Two 600 MW Generating Units in Yangzhou No.2 Thermal Power Plant
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作者 蒯狄正 《Electricity》 2001年第2期11-15,共5页
The problems including excessive flow of attemperating water for boiler, failure of butterfly valve at the outlet of circulating water pump, burnt-out of thyristor for excitation regulator, load variation rate of CCS ... The problems including excessive flow of attemperating water for boiler, failure of butterfly valve at the outlet of circulating water pump, burnt-out of thyristor for excitation regulator, load variation rate of CCS not complying with the contract target, etc. occurred during start-up and debugging of two 600 MW generating units in Yangzhou No.2 Thermal Power Plant. Through analysis on these problems. the remedial measures were put forward, to which can be referred for similar units. 展开更多
关键词 start-up and debugging problems analysis remedial measures 600 MW generating unit
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Thrust Analysis of a Fish Robot Actuated by Piezoceramic Composite Actuators 被引量:6
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作者 Quang Sang Nguyen Hoon Cheol Park Doyoung Byun 《Journal of Bionic Engineering》 SCIE EI CSCD 2011年第2期158-164,共7页
In this work, a three-dimensional (3D) Computational Fluid Dynamics (CFD) model was built to simulate the tail fin motion of a fish robot actuated by a piezoceramic composite actuator, and to determine the maximum... In this work, a three-dimensional (3D) Computational Fluid Dynamics (CFD) model was built to simulate the tail fin motion of a fish robot actuated by a piezoceramic composite actuator, and to determine the maximum thrust tail-beat frequency. A simulation of the tail fin at a tail-beat frequency was performed to confirm measured thrust data from a previous study. The computed and measured thrusts were in good agreement. A series of thrust simulations were conducted for various tail-beat frequencies to confirm the maximum thrust frequency that was obtained from thrust measurements in the previous study. The largest thrust was calculated at a tail-beat frequency of 3.7 Hz and vortices around the tail were fully separated. The calculated maximum thrust tail-beat frequency was in good agreement with the measured frequency. Flow characteristics during tail fin motion were examined to explain why the largest thrust occurred at this particular tail-beat frequency. 展开更多
关键词 fish robot CFD LIPCA thrust measurement thrust analysis composite actuator vortex shedding
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Importance Measure Analysis for Use in Dynamic Performance Design of a Co-cured Composite Damping Instrument Panel
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作者 郝文锐 梁森 《Journal of Donghua University(English Edition)》 EI CAS 2017年第6期780-783,共4页
For the best dynamic performance of a co-cured composite damping instrument panel with light weight and high strength, a multilayer sandwich structure with polymethaerylimide (PMI) foam combined with embedded and co... For the best dynamic performance of a co-cured composite damping instrument panel with light weight and high strength, a multilayer sandwich structure with polymethaerylimide (PMI) foam combined with embedded and co-cured composite damping structure is proposed. The struetue can maintain the excellent mechanical properties of composite materials, and achieve the damping and light effect at the same time. Input variables which may affect the dynamic performance of the instrument panel were selected and variance based importance measure was analyzed through multi- finite element method (FEM) analysis. Using the results of the importance measure analysis, with other design requirements, the important design variable was optimized and an instrument panel with the best dynamic performance under the requirements of light weight and high strength was obtained. The structure of the instrument panel can provide reference for the design of precision, high speed, and dynamic composite component. The importance measure analysis of dynamic performance of the instrument panel can provide a reference for relative design. 展开更多
关键词 composite material damping membrane muln'layer sandwich structure dynamic performance importance measure analysis
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Real-time Capturing and Measurement of Traffic Flow Based on WinPcap
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作者 胡文静 李明 +1 位作者 仇润鹤 刘锦高 《Journal of Donghua University(English Edition)》 EI CAS 2006年第2期103-106,共4页
In order to understand how a network is being used or whether it is being abused, an administrator needs to inspect the flow of the traffic and "infers" the intent of the users and applications. So the network traff... In order to understand how a network is being used or whether it is being abused, an administrator needs to inspect the flow of the traffic and "infers" the intent of the users and applications. So the network traffic measurement and analysis are crucial to network monitoring, reliable DDoS detecting and attack source locating as well. In this paper, we discuss the principle of real-time network traffic measurement and analysis through embedding a traffic measurement and analysis engine into IP packet-decoding module, and emphasize the implementation of visualizing the real-time network traffic, which are helpful to network monitoring and network traffic modeling. 展开更多
关键词 Network traffic Traffic measurement and analysis WINPCAP Network monitoring.
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Analysis and counter measure in blood grouping errors of volunteers’donating blood
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《中国输血杂志》 CAS CSCD 2001年第S1期378-,共1页
关键词 analysis and counter measure in blood grouping errors of volunteers
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A Measurement of the Contribution Made by Foreign Investment to Chinese Economy
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作者 Guojie Zhao Xiaogeng Wang Jiayun Chang 《Chinese Business Review》 2005年第10期21-24,33,共5页
The author uses the statistics from 1981 to 2002 to perform a logarithmic regression analysis on the contribution made by foreign investment to Chinese economy. The measurement shows that the following effects on Chin... The author uses the statistics from 1981 to 2002 to perform a logarithmic regression analysis on the contribution made by foreign investment to Chinese economy. The measurement shows that the following effects on Chinese economy are brought by large amount of foreign investment: 1) Foreign investment, as an important investment source, boosts the increase of the stock of production factors and improves the supplying potentials of Chinese economy. 2) The application of foreign investment speeds the rapid growth of the total production value and the increases the value of Chinese industry. 3) Foreign investment changes the employment structure of Chinese labor force. 4) The tax in China, to some extent, owes its growth to the adoption of foreign investment. 展开更多
关键词 foreign investment developmer of Chinese economy measurement of contribution logarithmic regression analysis
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Coal pillar mechanics of violent failure in U.S. Mines 被引量:7
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作者 Maleki Hamid 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2017年第3期387-392,共6页
This paper seeks to enhance the understanding that the horizontal stresses build up and release during coal pillar loading and unloading(post-failure) drawing upon three decades of observations, geomechanical monitori... This paper seeks to enhance the understanding that the horizontal stresses build up and release during coal pillar loading and unloading(post-failure) drawing upon three decades of observations, geomechanical monitoring and numerical modeling in bump-prone U.S. mines. The focus is on induced horizontal stress in mine pillars and surrounding strata as highly stressed pillars punch into the roof and floor, causing shear failure and buckling of strata; under stiff stratigraphic units of some western US mines, these events could be accompanied by violent failure of pillar cores. Pillar punching eventually results in tensile stresses at the base of the pillar, facilitating transition into the post-failure regime; this transition will be nonviolent if certain conditions are met, notably the presence of interbedded mudstones with low shear strength properties and proper mine designs for controlling seismicity and dynamic loads. The study clearly shows high confining stress build-up in coal pillars resulting in up to twice higher peak vertical stress and high strain energy accumulations in some western US mines in comparison with peak stresses predicted using common empirical pillar design methods. It is the unstable release of this strain energy that can cause significant damage resulting from pillar dilation and ground movements. These forces are much greater than the capacity of most common internal support systems, resulting in horizontal stressinduced roof falls locally, in mines under unremarkable far-field horizontal stress. Attention should be placed on pillar designs as increasing support density may prove to be ineffective. This mechanism is analyzed using field measurements and generic finite-difference stress analyses. The study confirms the higher load carrying capacity of confinement-controlled coal seams in comparison with structurally controlled coal seams. Such significant differences in confining stresses are not taken into account when estimating peak pillar strength using most common empirical techniques such as those proposed by Bieniawski and Salamon. While using lower pillar strength estimates may be considered conservative,it underestimates the actual capacity of pillars in accumulating much higher stress and strain energies,misleading the designer and inadvertently diminishing mine safety. The role of induced horizontal stress in mine pillars and surrounding strata is emphasized in coal pillar mechanics of violent failure. The triggering mechanism for the violent events is sudden loss of pillar confinement due to dynamic loading resulting from failure of overlying stiff and strong strata. Evidence of such mechanism is noted in the field by observed red-dust at the coal-rock interfaces at the location of coal bumps and irregular, periodic caving in room-and-pillar mines quantified through direct pressure measurements in the gob. 展开更多
关键词 Rockburst and coal bumps Field measurements Stress analysis Mechanics Horizontal stress
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Evaluation of Latest TMPA and CMORPH Precipitation Products with Independent Rain Gauge Observation Networks over High-latitude and Low-latitude Basins in China 被引量:11
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作者 JIANG Shanhu REN Liliang +3 位作者 YONG Bin HONG Yang YANG Xiaoli YUAN Fei 《Chinese Geographical Science》 SCIE CSCD 2016年第4期439-455,共17页
The Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) and National Oceanic and Atmospheric Administration (NOAA) Climate Prediction Center (CPC) morphing technique (CMO... The Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) and National Oceanic and Atmospheric Administration (NOAA) Climate Prediction Center (CPC) morphing technique (CMORPH) are two important multi-satellite precipitation products in TRMM-era and perform important functions in GPM-era. Both TMPA and CMORPH systems simultaneously upgraded their retrieval algorithms and released their latest version of precipitation data in 2013. In this study, the latest TMPA and CMORPH products (i.e., Version-7 real-time TMPA (T-rt) and gauge-adjusted TMPA (T-adj), and Version- 1.0 real-time CMORPH (C-rt) and Version-l.0 gauge-adjusted CMORPH (C-adj)) are evaluated and intercompared by using independent rain gauge observations for a 12-year (2000--2011) period over two typical basins in China with different geographical and climate conditions. Results indicate that all TMPA and CMORPH products tend to overestimate precipitation for the high-latitude semiarid Laoha River Basin and underestimate it for the low-latitude humid Mishui Basin. Overall, the satellite precipitation products exhibit superior performance over Mishui Basin than that over Laoha River Basin. The C-adj presents the best performance over the high-latitude Laoha River Basin, whereas T-adj showed the best performance over the low-latitude Mishui Basin. The two gauge-adjusted products demonstrate potential in water resource management. However, the accuracy of two real-time satellite precipitation products demonstrates large variability in the two validation basins. The C-rt reaches a similar accuracy level with the gauge-adjusted satellite precipitation products in the high-latitude Laoha River Basin, and T-rt performs well in the low-latitude Mishui Basin. The study also reveals that all satellite precipitation products obviously overestimate light rain amounts and events over Laoha River Basin, whereas they underestimate the amount and events over Mishui Basin. The findings of the precision characteristics associated with the latest TMPA and CMORPH precipitation products at different basins will offer satellite pre- cipitation users an enhanced understanding of the applicability of the latest TMPA and CMORPH for water resource management, hydrologic process simulation, and hydrometeorological disaster prediction in other similar regions in China. The findings will also be useful for IMERG algorithm development and update in GPM-era. 展开更多
关键词 satellite precipitation Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation analysis (TMPA) Cli-mate Prediction Center morphing technique (CMORPH) precision evaluation
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Early performance of Pinus radiata provenances in the earthquakeravaged dry river valley area of Sichuan, southwest China
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作者 Huiquan Bi Rongwei Li +4 位作者 Zongxing Wu Quan Huang Qianli Liu Yongli Zhou Yun Li 《Journal of Forestry Research》 SCIE CAS CSCD 2013年第4期619-632,共14页
A provenance experiment involving five native provenances and an Australian landrace of Pinus radiata (D. Don) was established over three sites in the dry river valley area of Sichuan, southwest China in 2004 in ord... A provenance experiment involving five native provenances and an Australian landrace of Pinus radiata (D. Don) was established over three sites in the dry river valley area of Sichuan, southwest China in 2004 in order to select the most suitable provenance for environmental planting on the dry, steep and degraded slopes to reduce soil erosion. Although with much lower soil moisture supply and mean minimum temperatures in winter compared to P. radiata provenance trials estab- lished elsewhere in the world, these sites are within the working limits of the species defined by previous climate modelling and matching. Be- cause of the difficult site conditions and severe natural disturbances after the experiment was established, mortality was high across the three sites in comparison to provenance trials in other countries. 展开更多
关键词 Pinus radiata dryland provenance performance multilevellinear mixed models repeated measures analysis
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Geotechnical investigations and remediation design for failure of tunnel portal section: a case study in northern Turkey 被引量:7
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作者 Ayberk KAYA Kadir KARAMAN Fikri BULUT 《Journal of Mountain Science》 SCIE CSCD 2017年第6期1140-1160,共21页
Mass movements are very common problems in the eastern Black Sea region of Turkey due to its climate conditions, geological, and geomorphological characteristics. High slope angle, weathering, dense rainfalls, and ant... Mass movements are very common problems in the eastern Black Sea region of Turkey due to its climate conditions, geological, and geomorphological characteristics. High slope angle, weathering, dense rainfalls, and anthropogenic impacts are generally reported as the most important triggering factors in the region. Following the portal slope excavations in the entrance section of Cankurtaran tunnel, located in the region, where the highly weathered andesitic tuff crops out, a circular toe failure occurred. The main target of the present study is to investigate the causes and occurrence mechanism of this failure and to determine the feasible remedial measures against it using finite element method(FEM) in four stages. These stages are slope stability analyses for pre-and postexcavation cases, and remediation design assessments for slope and tunnel. The results of the FEM-SSR analyses indicated that the insufficient initial support design and weathering of the andesitic tuffs are the main factors that caused the portal failure. After installing a rock retaining wall with jet grout columns and reinforced slope benching applications, the factor of safety increased from 0.83 to 2.80. In addition toslope stability evaluation, the Rock Mass Rating(RMR), Rock Mass Quality(Q) and New Austrian Tunneling Method(NATM) systems were also utilized as empirical methods to characterize the tunnel ground and to determine the tunnel support design. The performance of the suggested empirical support design, induced stress distributions and deformations were analyzed by means of numerical modelling. Finally, it was concluded that the recommended stabilization technique was essential for the dynamic long-term stability and prevents the effects of failure. Additionally, the FEM method gives useful and reasonably reliable results in evaluating the stability of cut slopes and tunnels excavated both in continuous and discontinuous rock masses. 展开更多
关键词 Portal failure Stability analysis Finite element method Tunnel support design Remedial measures Rock Mass Rating(RMR) Rock Mass Quality(Q) New Austrian Tunneling Method(NATM)
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Difficulties and measures of driving super long piles in Bohai Gulf
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作者 Shuwang Yan Jia Li +1 位作者 Liqiang Sun Guomin Sun 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2015年第2期69-73,共5页
Long piles of the ocean oil platform are usually manufactured as the integration of several segments, which have to be assembled one by one during installation. During pile driving, excessive pore pressure will build ... Long piles of the ocean oil platform are usually manufactured as the integration of several segments, which have to be assembled one by one during installation. During pile driving, excessive pore pressure will build up in such a high level that hydraulic fracturing in the soil round the pile may take place, which will cause the soil to consolidate much faster during pile extension period. Consequently, after pile extension, the soil strength will recover to some extent and the driving resistance will increase considerably, which makes restarting driving the pile very difficult and even causes refusal. A finite element (FE) analysis procedure is presented for judging the risk of refusal by estimating the blow counts after pile extension, in which the regain of soil strength is considered. A case analysis in Bohai Gulf is performed using the proposed orocedure to exolain the nile refusal phenomenon. 展开更多
关键词 Super long pile driving Refusal Excessive pore pressure Hydraulic fracture Finite element analysis Prevent measures
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Uncertainty analysis of a pavement reflectance measurement system based on a gonio-photometer
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作者 樊生龙 刘木清 沈海平 《Chinese Optics Letters》 SCIE EI CAS CSCD 2014年第5期29-32,共4页
A pavement reflectance measurement system is established based on a gonio-photometerexisting by chang- ing a bracket to carry the road sample and luminance meter, adding a collimated light source to provide incident l... A pavement reflectance measurement system is established based on a gonio-photometerexisting by chang- ing a bracket to carry the road sample and luminance meter, adding a collimated light source to provide incident light. This automated system could finish the reflection measurement of a road sample in 4 h. An uncertainty budget of this measurement system is made and the combined standard uncertainty of Q0 is 5.26%. 展开更多
关键词 Uncertainty analysis of a pavement reflectance measurement system based on a gonio-photometer
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Measurment of gas-liquid two-phase slug flow with a Venturi meter based on blind source separation
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作者 王微微 梁霄 张明柱 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2015年第9期1447-1452,共6页
We propose a novel flow measurement method for gas–liquid two-phase slug flow by using the blind source separation technique. The flow measurement model is established based on the fluctuation characteristics of diff... We propose a novel flow measurement method for gas–liquid two-phase slug flow by using the blind source separation technique. The flow measurement model is established based on the fluctuation characteristics of differential pressure(DP) signals measured from a Venturi meter. It is demonstrated that DP signals of two-phase flow are a linear mixture of DP signals of single phase fluids. The measurement model is a combination of throttle relationship and blind source separation model. In addition, we estimate the mixture matrix using the independent component analysis(ICA) technique. The mixture matrix could be described using the variances of two DP signals acquired from two Venturi meters. The validity of the proposed model was tested in the gas–liquid twophase flow loop facility. Experimental results showed that for most slug flow the relative error is within 10%.We also find that the mixture matrix is beneficial to investigate the flow mechanism of gas–liquid two-phase flow. 展开更多
关键词 Two-phase slug flow Flow measurement Differential pressure Blind source separation Independent component analysis
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The Use of Repeated Measures Analysis of Variance to Study the Effect of Phlegm-Heat Syndrome on Neurological Deficits in Patients with Stroke~ 被引量:3
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作者 Xi-yan Xin 辛喜艳 (11087) Ying Gao 高 颖 (11087) 《Chinese Journal of Integrative Medicine》 SCIE CAS 2013年第8期568-572,共5页
Objective: To explore the effect of phlegm-heat syndrome on the degree of neurological deficit and provide some data support for the correct recognition of the relationship between phlegm-heat syndrome and neurologic... Objective: To explore the effect of phlegm-heat syndrome on the degree of neurological deficit and provide some data support for the correct recognition of the relationship between phlegm-heat syndrome and neurological deficits in stroke patients. Methods: Clinical information were collected on 294 patients with acute ischemic stroke (AIS) whose syndrome and National Institute of Health stroke scale (NIHSS) score were checked at baseline (within the first 3-day admission) and at 7, 14, 28, and 90 days after admission to our clinical research centre. We explored the effect of phlegm-heat syndrome on the degree of neurological deficit following stroke by applying a repeated measures analysis of variance. Results: Stroke patients with phlegm-heat syndrome had higher NIHSS score than patients without the syndrome (P〈0.01), and there appeared to be a decrease in NIHSS score over time in all patients (P〈0.01). Conduslons: Phlegm-heat syndrome in patients who have suffered stroke has an effect on the degree of neurological deficiency. Disappearance of phlegm-heat syndrome may improve the degree of neurological deficit observed in stroke patients. 展开更多
关键词 ischemic stroke phlegm-heat syndrome neurological deficiency repeated measures analysis ofvariance
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Regional moment-independent sensitivity analysis with its applications in engineering 被引量:8
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作者 Changcong ZHOU Chenghu TANG +2 位作者 Fuchao LIU Wenxuan WANG Zhufeng YUE 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2017年第3期1031-1042,共12页
Traditional Global Sensitivity Analysis(GSA) focuses on ranking inputs according to their contributions to the output uncertainty.However,information about how the specific regions inside an input affect the output ... Traditional Global Sensitivity Analysis(GSA) focuses on ranking inputs according to their contributions to the output uncertainty.However,information about how the specific regions inside an input affect the output is beyond the traditional GSA techniques.To fully address this issue,in this work,two regional moment-independent importance measures,Regional Importance Measure based on Probability Density Function(RIMPDF) and Regional Importance Measure based on Cumulative Distribution Function(RIMCDF),are introduced to find out the contributions of specific regions of an input to the whole output distribution.The two regional importance measures prove to be reasonable supplements of the traditional GSA techniques.The ideas of RIMPDF and RIMCDF are applied in two engineering examples to demonstrate that the regional moment-independent importance analysis can add more information concerning the contributions of model inputs. 展开更多
关键词 Cumulative distribution function Moment-independent Probability density function Regional importance measure Sensitivity analysis Uncertainty
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Research on uncertainty in measurement assisted alignment in aircraft assembly 被引量:17
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作者 Chen Zhehan Du Fuzhou Tang Xiaoqing 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2013年第6期1568-1576,共9页
Operations in assembling and joining large size aircraft components are changed to novel digital and flexible ways by digital measurement assisted alignment.Positions and orientations(P&O)of aligned components are ... Operations in assembling and joining large size aircraft components are changed to novel digital and flexible ways by digital measurement assisted alignment.Positions and orientations(P&O)of aligned components are critical characters which assure geometrical positions and relationships of those components.Therefore,evaluating the P&O of a component is considered necessary and critical for ensuring accuracy in aircraft assembly.Uncertainty of position and orientation(U-P&O),as a part of the evaluating result of P&O,needs to be given for ensuring the integrity and credibility of the result;furthermore,U-P&O is necessary for error tracing and quality evaluating of measurement assisted aircraft assembly.However,current research mainly focuses on the process integration of measurement with assembly,and usually ignores the uncertainty of measured result and its influence on quality evaluation.This paper focuses on the expression,analysis,and application of U-P&O in measurement assisted alignment.The geometrical and algebraical connotations of U-P&O are presented.Then,an analytical algorithm for evaluating the multi-dimensional U-P&O is given,and the effect factors and characteristics of U-P&O are discussed.Finally,U-P&O is used to evaluate alignment in aircraft assembly for quality evaluating and improving.Cases are introduced with the methodology. 展开更多
关键词 Aircraft manufacturing Large size components alignment measurement assisted assembly Quality assurance Uncertainty analysis Uncertainty of position and orientation
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