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Anomaly Detection Using Data Rate of Change on Medical Data
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作者 Kwang-Cheol Rim Young-Min Yoon +1 位作者 Sung-Uk Kim Jeong-In Kim 《Computers, Materials & Continua》 SCIE EI 2024年第9期3903-3916,共14页
The identification and mitigation of anomaly data,characterized by deviations from normal patterns or singularities,stand as critical endeavors in modern technological landscapes,spanning domains such as Non-Fungible ... The identification and mitigation of anomaly data,characterized by deviations from normal patterns or singularities,stand as critical endeavors in modern technological landscapes,spanning domains such as Non-Fungible Tokens(NFTs),cyber-security,and the burgeoning metaverse.This paper presents a novel proposal aimed at refining anomaly detection methodologies,with a particular focus on continuous data streams.The essence of the proposed approach lies in analyzing the rate of change within such data streams,leveraging this dynamic aspect to discern anomalies with heightened precision and efficacy.Through empirical evaluation,our method demonstrates a marked improvement over existing techniques,showcasing more nuanced and sophisticated result values.Moreover,we envision a trajectory of continuous research and development,wherein iterative refinement and supplementation will tailor our approach to various anomaly detection scenarios,ensuring adaptability and robustness in real-world applications. 展开更多
关键词 Anomaly data anomaly detection medical anomaly data cyber security rate of change
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Doppler Effect: A Look from Biology Aging
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作者 Jorge Barragán Sebastián Sánchez 《Advances in Aging Research》 CAS 2024年第4期75-84,共10页
The Doppler effect can be defined as the frequency shift suffered by a wave phenomenon, when there is a difference in relative speed between the waves generated and their source. We know that it occurs in the case of ... The Doppler effect can be defined as the frequency shift suffered by a wave phenomenon, when there is a difference in relative speed between the waves generated and their source. We know that it occurs in the case of mechanical and electromagnetic waves. We propose to generalize the Doppler effect to the case of frequency changes of certain oscillatory variables in biology before and after puberty, starting from the basis that a metabolically accelerated system is equivalent to a mechanically accelerated system. We then established the following objectives: To verify if there is an average difference in heart and respiratory rates, before and after puberty. To verify the association of these frequency differences with the metabolic activity estimated as basal metabolic rate or BMR. We studied heart and respiratory rate data from healthy people of both sexes, verifying the frequency distribution before and after puberty. We also study the relationship of the frequency distribution with the evolution of the basal metabolic rate throughout life. Analysis of the results shows that the highest heart and respiratory rates occur before puberty, while the lowest rates occur after puberty. A high correlation of the evolution of the variables studied with the evolution of the metabolic acceleration of the system throughout life is also evident. Taking into account that a mechanically accelerated system is equivalent to a metabolically accelerated system, we can conclude that the frequency distribution found is the expression of a generalization of the Doppler effect in the case of biological physical systems. 展开更多
关键词 Oscillatory Variables Metabolic Acceleration Mechanical Acceleration Equivalence Principle Non-Inertial System Rate of Change
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Trends in gravity changes from 2009 to 2013 derived from ground-based gravimetry and GRACE data in North China 被引量:3
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作者 Shen Chongyang Xuan Songbai +1 位作者 Zou Zhengbo Wu Guiju 《Geodesy and Geodynamics》 2015年第6期423-428,共6页
North China is a key region for studying geophysical progress. In this study, ground-based and Gravity Recovery and Climate Experiment(GRACE) gravity data from 2009 to 2013 are used to calculate the gravity change r... North China is a key region for studying geophysical progress. In this study, ground-based and Gravity Recovery and Climate Experiment(GRACE) gravity data from 2009 to 2013 are used to calculate the gravity change rate(GCR) using the polynomial fitting method. In general, the study area was divided into the Shanxi rift, Jing-Jin-Ji(Beijing-Tianjin-Hebei Province), and Bohai Bay Basin(BBB) regions. Results of the distribution of the GCR determined from ground-based gravimetry show that the GCR appears to be "negativepositive-negative" from west to east, which indicates that different geophysical mechanisms are involved in the tectonic activities of these regions. However, GRACE solutions are conducted over a larger spatial scale and are able to show a difference between southern and northern areas and a mass redistribution of land water storage. 展开更多
关键词 North China Ground-based gravimetry Gravity Recovery and Climate Experiment(GRACE) Polynomial fitting method Gravity changes rate Tectonic activities Geophysical mechanisms Mass redistribution
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The changes on microstructure,levels of recovery rate and CD62P,PAC-Ⅰof cryopreserved platelets
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《中国输血杂志》 CAS CSCD 2001年第S1期412-,共1页
关键词 rate The changes on microstructure levels of recovery rate and CD62P PAC of cryopreserved platelets CD
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Parallel Integrated Model-Driven and Data-Driven Online Transient Stability Assessment Method for Power System
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作者 Ying Zhang Xiaoqing Han +3 位作者 Chao Zhang Ying Qu Yang Liu Gengwu Zhang 《Energy Engineering》 EI 2023年第11期2585-2609,共25页
More and more uncertain factors in power systems and more and more complex operation modes of power systems put forward higher requirements for online transient stability assessment methods.The traditional modeldriven... More and more uncertain factors in power systems and more and more complex operation modes of power systems put forward higher requirements for online transient stability assessment methods.The traditional modeldriven methods have clear physical mechanisms and reliable evaluation results but the calculation process is time-consuming,while the data-driven methods have the strong fitting ability and fast calculation speed but the evaluation results lack interpretation.Therefore,it is a future development trend of transient stability assessment methods to combine these two kinds of methods.In this paper,the rate of change of the kinetic energy method is used to calculate the transient stability in the model-driven stage,and the support vector machine and extreme learning machine with different internal principles are respectively used to predict the transient stability in the data-driven stage.In order to quantify the credibility level of the data-driven methods,the credibility index of the output results is proposed.Then the switching function controlling whether the rate of change of the kinetic energy method is activated or not is established based on this index.Thus,a newparallel integratedmodel-driven and datadriven online transient stability assessment method is proposed.The accuracy,efficiency,and adaptability of the proposed method are verified by numerical examples. 展开更多
关键词 Rate of change of kinetic energy support vectormachine extreme learning machine credibility index model-data parallel integration
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An Improved DITC Control Method Based on Turn-on Angle Optimization
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作者 Chaozhi Huang Wensheng Cao +2 位作者 Zhou Chen Yuliang Wu Yongmin Geng 《CES Transactions on Electrical Machines and Systems》 CSCD 2023年第4期379-389,共11页
Switched reluctance motor(SRM)usually adopts Direct Instantaneous Torque Control(DITC)to suppress torque ripple.However,due to the fixed turn-on angle and the control mode of the two-phase exchange region,the conventi... Switched reluctance motor(SRM)usually adopts Direct Instantaneous Torque Control(DITC)to suppress torque ripple.However,due to the fixed turn-on angle and the control mode of the two-phase exchange region,the conventional DITC control method has low adaptability in different working conditions,which will lead to large torque ripple.For this problem,an improved DITC control method based on turn-on angle optimization is proposed in this paper.Firstly,the improved BP neural network is used to construct a nonlinear torque model,so that the torque can be accurately fed back in real time.Secondly,the turn-on angle optimization algorithm based on improved GRNN neural network is established,so that the turn-on angle can be adjusted adaptively online.Then,according to the magnitude of inductance change rate,the two-phase exchange region is divided into two regions,and the phase with larger inductance change rate and current is selected to provide torque in the sub-regions.Finally,taking a 3-phase 6/20 SRM as example,simulation and experimental verification are carried out to verify the effectiveness of this method. 展开更多
关键词 Switched Reluctance Motor Turn-on Angle Optimization Neural Network Inductance Change Rate Torque Ripple
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A Doppler Location Method Based on Virtual Path Difference
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作者 Yu Tao 《Journal of Electronic & Information Systems》 2023年第1期20-25,共6页
This paper presents a Doppler passive location method for moving targets with fixed single station using the Doppler frequency shift and time difference information.First,based on the relationship between frequency sh... This paper presents a Doppler passive location method for moving targets with fixed single station using the Doppler frequency shift and time difference information.First,based on the relationship between frequency shift and path difference,the virtual path difference is calculated from the measured value of Doppler frequency shift by means of mean value correction.Then,under the assumption that the target is moving at a constant speed along a straight line,two coaxial virtual double base arrays are constructed by using the moving track of the moving target based on the method of fixed period time difference.On this basis,the moving distance of the moving target can be calculated by using the ratio relationship between the frequency difference and the radial distance between the two adjacent detection points in the middle of the array,and the linear solution of the two double base path difference positioning equations.At this point,the relative coordinate position of the moving target can be obtained by directly using the linear solution of the double base path difference positioning equation again. 展开更多
关键词 Fixed single station Passive location Doppler frequency Doppler frequency change rate Frequency shift-path difference equation Virtual path difference
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Study on the Daily Change of Photosynthetic Rate for Prunus domestica × armeniacain Different Seasons 被引量:3
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作者 李雯雯 冯贝贝 +5 位作者 魏雅君 牛莹莹 徐业勇 王明 杨红丽 廖康 《Agricultural Science & Technology》 CAS 2016年第4期838-844,941,共8页
[Objective] The aim of this study was to explore the daily change of photosyntheticratefor Prunus domestica ×armeniacain different growing seasons. The study can provide theoretical basis for arid area high yield... [Objective] The aim of this study was to explore the daily change of photosyntheticratefor Prunus domestica ×armeniacain different growing seasons. The study can provide theoretical basis for arid area high yield and quality cultivation.[Method] The photosynthetic physiological properties of leaves of different types of Prunus domestica × armeniaca were measured by the Li-6400 portable photosynthesis system indifferent seasons. By this method could analysis of photosyntheticcharacteristicsfor different types of Prunus domestica×armeniaca in different seasons.[Result] Daily change of photosyntheticrate(Pn) for Prunus domestica×armeniaca in differentseasons showed a "double-peak" curve. The peak values were at 10:00 and16:00. The Pn of ‘Fengweihuanghou', ‘Konglongdan', ‘Weihou', ‘Weiwang' and‘Weidi' reached the maximum in July, theywere 13.75, 14.76, 12.96, 13.3, and 11.9μmol/(m^2·s), respectively. The Pn of Prunus domestica×armeniaca reached minimumin August, they were 9.78, 10.71, 12.02, 10.43 μmol/(m^2·s). The Pn overall average of ‘Konglongdan' was highest,it reached 12.65 μmol/(m^2·s).The Pn overall average of ‘Weiwang' was lowest, it reached 11.31μmol/(m^2·s). There were extremely significant positive correlation between the Pn and Gs(P0.01). [Conclusion] Daily change of photosyntheticrate for Prunus domestica ×armeniaca in differentseasons showed a "double-peak" curve, showing significant phenomenon of "midday depression".The photosynthesis intensity of Prunus domestica ×armeniaca was strongest in July, and the photosynthesis intensity was weakest in August. ‘Konglongdan'showed the strongest photosynthesis capacity, ‘Weihou' and ‘Weiwang', followed.There were highest correlation between the Pn and stoma conductance(Gs). 展开更多
关键词 Prunus domestica × armeniaca Net photosynthetic rate Daily change of photosynthetic rate Environmental factors
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Sea level change and forecast in the future — climate of the past,today and the future 被引量:1
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作者 岳军 DONG yue +3 位作者 陈满春 韩芳 段焕春 王国明 《Marine Science Bulletin》 CAS 2011年第2期33-50,共18页
The sea-level change is resulted from superposition of sun, moon and other planeries, and earth itself, biological process, atmosphere and oceanography, as well as artificial actions. As a result, the sea level change... The sea-level change is resulted from superposition of sun, moon and other planeries, and earth itself, biological process, atmosphere and oceanography, as well as artificial actions. As a result, the sea level change is really a sensitive integral variation value of many variations, or a combined function of coupling effects of various big systems. Therefore the above mentioned superposed action of different systems and the coupling effect of sun earth and biological aspects may be called as sun earth biological coupling effect system. Based on this hypothesis, the corresponding sun dynamic, air dynamic, water dynamic and earth dynamic conceptional models are established in order to research the multiple coupling effects and feedback machsnism between these big systems. In order to determine the relations, effectness and coherent relation of different variations, the quantity, analysis is conducted through collective variation and stage division. The quantity analysis indicates that the earths spindle rotation speed is the dynamic mechanism controlling the sea level change of fluctuation. The change rate of sea level in the world is +1.32 + 0.22 mm/a, while the sea level change rate in China is only+1.39 + 0.26 mm/a in average. If take the CO2 content as the climate marker, eight cold stages (periods) are grouped out since two hundreds years AC. The extreme cold of the eighth cold stage started approximately at 1850 years AC. and if the stage from the extreme cold to extreme warm is determined as long as 200 years, the present ongoing warm stage will end at about 2050 years, there after the temperature will begin to tower. If the stage between cold and warm extremes lasts for 250 years, then the temperature will become lower at about 2100 year. Until to that time, the sea-level is estimated to raise +7 - +11 + 3.5 cm again, and there after, the sea level will begin the new lowering trend. In the same time, the climate will enter into next new cold stage subsequently. 展开更多
关键词 Sun earth biological coupling effect system sea-level change mechanism change rate of the sea-level climate cold stage forecast of the sea-level changes in the future
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Spatiotemporal variability of permafrost degradation on the Qinghai-Tibet Plateau 被引量:19
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作者 HuiJun Jin DongLiang Luo ShaoLing Wang LanZhi Lv JiChun Wu 《Research in Cold and Arid Regions》 2011年第4期281-305,共25页
Based on data from six meteorological stations in the permafrost regions, 60 boreholes for long-term monitoring of permafrost temperatures, and 710 hand-dug pits and shallow boreholes on the Qinghai-Tibet Plateau (QT... Based on data from six meteorological stations in the permafrost regions, 60 boreholes for long-term monitoring of permafrost temperatures, and 710 hand-dug pits and shallow boreholes on the Qinghai-Tibet Plateau (QTP), the spatiotemporal variability of permafrost degradation was closely examined in relation to the rates of changes in air, surface, and ground temperatures. The de- cadal averages and increases in the mean annual air temperatures (MAATs) from 1961-2010 were the largest and most persistent during the last century. MAATs rose by 1.3 ℃, with an average increase rate of 0.03 ℃/yr. The average of mean annual ground surface temperatures (MAGSTs) increased by 1.3 ℃ at an average rate of 0.03 ℃/yr. The rates of changes in ground temperatures were -0.01 to 0.07 ℃/yr. The rates of changes in the depths of the permafrost table were -1 to +10 cm/yr. The areal extent of permafrost on the QTP shrank from about 1.50× 10^6 km^2 in 1975 to about 1.26× 10^6 km^2 in 2006. About 60% of the shrinkage in area of permafrost occurred during the period from 1996 to 2006. Due to increasing air temperature since the late 1980s, warm (〉-1 ℃) permafrost has started to degrade, and the degradation has gradually expanded to the zones of transitory (-1 to -2 ℃) and cold (〈-2 ℃) permafrost. Permafrost on the southern and southeastem plateau degrades more markedly. It is projected that the degradation of permafrost is likely to accelerate, and substantial changes in the distributive features and thermal regimes of permafrost should be anticipated. However, regarding the relationships between degrading permafrost and the degradation of rangelands, it is still too early to draw reliable conclusions due to inadequate scientific criteria and evidence. 展开更多
关键词 QTP permafrost degradation ground temperatures change rates
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Research on Passive Locating Method Using Phase Rate of Change with Variant Posture of the Observer 被引量:4
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作者 单月晖 安玮 +1 位作者 孙仲康 皇甫堪 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2002年第3期166-170,共5页
Technology of passive location has broad prospects in applications. In this paper, the method using the phase rate of change for the single observer passive location is introduced based on existing methods. One can ob... Technology of passive location has broad prospects in applications. In this paper, the method using the phase rate of change for the single observer passive location is introduced based on existing methods. One can obtain the direction of the target with phase information of two orthogonal interferometers on the observer and the radial distance with the corresponding phase rate of change. Then the target can be located with high speed and precision. A locating approach is given when the flying posture of t... 展开更多
关键词 PHASE rate of change single observer passive location variant posture direction radial distance MGEKF
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Determination of ultimate bearing capacity of uplift piles using intact and non-intact load−displacement curve 被引量:5
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作者 WANG Qin-ke MAJian-lin +2 位作者 JI Yu-kun ZHANG Jian CHEN Wen-long 《Journal of Central South University》 SCIE EI CAS CSCD 2022年第2期470-485,共16页
Based on the field destructive test of six rock-socketed piles with shallow overburden,three prediction models are used to quantitatively analyze and predict the intact load−displacement curve.The predicted values of ... Based on the field destructive test of six rock-socketed piles with shallow overburden,three prediction models are used to quantitatively analyze and predict the intact load−displacement curve.The predicted values of ultimate uplift capacity were further determined by four methods(displacement controlling method(DCM),reduction coefficient method(RCM),maximum curvature method(MCM),and critical stiffness method(CSM))and compared with the measured value.Through the analysis of the relationship between the change rate of pullout stiffness and displacement,a method used to determine the ultimate uplift capacity via non-intact load−displacement curve was proposed.The results show that the predicted value determined by DCM is more conservative,while the predicted value determined by MCM is larger than the measured value.This suggests that RCM and CSM in engineering applications can be preferentially applied.Moreover,the development law of the change rate of pullout stiffness with displacement agrees well with the attenuation form of power function.The theoretical predicted results of ultimate uplift capacity based on the change rate of pullout stiffness will not be affected by the integrity of the curve.The method is simple and applicable for the piles that are not loaded to failure state,and thus provides new insights into ultimate uplift capacity determination of test piles. 展开更多
关键词 load−displacement curve prediction model determination method of bearing capacity change rate of pullout stiffness
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Effects of precipitation variation on severe acid rain in southern China 被引量:3
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作者 谢志清 杜银 +3 位作者 曾燕 李亚春 严明良 焦圣明 《Journal of Geographical Sciences》 SCIE CSCD 2009年第4期489-501,共13页
Acid rain has been recognized as a serious environmental problem in China since the 1980s, but little is known about the effects of the climatic change in regional precipitation on the temporal and spatial variability... Acid rain has been recognized as a serious environmental problem in China since the 1980s, but little is known about the effects of the climatic change in regional precipitation on the temporal and spatial variability of severe acid rain. We present the effects of the regional precipitation trend change on the area and intensity of severe acid rain in southern China, and the spatio-temporal distribution characteristics of SO2 and NO2 concentrations are analyzed on the basis of SO2 and NO2 column concentration data. The results are as follows. (1) The emission levels of SO2 and NO2 have reached or passed the precipitation scavenging capacity in parts of southern China owing to the emission totals of SOz and NO2 increasing from 1993 to 2004. (2) Notable changes in the proportion of cities subject to severe acid rain occurred mainly in the south of the middle-lower reaches of the Yangtze River during 1993-2004. With an abrupt change in 1999, the severe acid rain regions were mainly located in central and western China during 1993-1999 and moved obviously eastward to the south of the lower-middle reaches of the Yangtze River with the proportion of cities subject to severe acid rain increasing significantly from 2000 to 2004. (3) The spatial distribution and variation in the seasonal precipitation change rate of more than 10 mm/10a are similar to those of severe acid rain in southern China. An abrupt change in 1999 is seen for winter and summer precipitation, the same as for the proportion of cities subject to severe acid rain in southern China. The significant increase in summer storm precipitation from 1991 to 1999 mitigated the annual precipitation acidity in the south of the Yangtze River and reduced the area of severe acid rainfall. On the other hand, the decrease in storm rainfall in summer expanded the area of severe acid rainfall in the south of the Yangtze River in 2000-2006. Therefore, the change in seasonal precipitation is an important factor in the severe acid rain regions moving eastward and expanding in southern China. 展开更多
关键词 acid rain spatial and temporal variations in seasonal precipitation climate change rate Mann-Kendall trend test
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Coastal transgression and regression from 1980 to 2020 and shoreline forecasting for 2030 and 2040,using DSAS along the southern coastal tip of Peninsular India 被引量:2
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作者 S.Chrisben Sam B.Gurugnanam 《Geodesy and Geodynamics》 CSCD 2022年第6期585-594,共10页
This study explains the multi-decadal shoreline changes along the coast of Kanyakumari from 1980 to2020.The shorelines are extracted from the Landsat images to estimate the shoreline dynamics and future predictions us... This study explains the multi-decadal shoreline changes along the coast of Kanyakumari from 1980 to2020.The shorelines are extracted from the Landsat images to estimate the shoreline dynamics and future predictions using Digital Shoreline Analysis System(DSAS).By the estimation of End Point Rate(EPR)and Linear Regression Rate(LRR),it is quantified that the maximum erosion is 5.01 m/yr(EPR)and 6.13 m/yr(LRR)consistently with the maximum accretion of 3.77 m/yr(EPR)and 3.11 m/yr(LRR)along the entire coastal stretch of 77 km.The future shoreline predicted using the Kalman filter forecasted that Inayam,Periyakattuthurai and Kodimunai are highly prone to erosion with a shift of 170 m,157 m and 145 m by 2030 and 194 m,182 m and 165 m by 2040 towards the land.Also,the western coast is highly prone to erosion and it is predicted that certain villages are prone to loss of economy and livelihood.The outcome of this study may guide the coastal researchers to understand the evolution and decisionmakers to evolve with alternative sustainable management plans in the future. 展开更多
关键词 Shoreline change rates Future prediction DSAS Kalman filter Erosion and accretion
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A novel index to evaluate discretization methods: A case study of flood susceptibility assessment based on random forest 被引量:2
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作者 Xianzhe Tang Takashi Machimura +2 位作者 Wei Liu Jiufeng Li Haoyuan Hong 《Geoscience Frontiers》 SCIE CAS CSCD 2021年第6期313-325,共13页
The selection of a suitable discretization method(DM) to discretize spatially continuous variables(SCVs)is critical in ML-based natural hazard susceptibility assessment. However, few studies start to consider the infl... The selection of a suitable discretization method(DM) to discretize spatially continuous variables(SCVs)is critical in ML-based natural hazard susceptibility assessment. However, few studies start to consider the influence due to the selected DMs and how to efficiently select a suitable DM for each SCV. These issues were well addressed in this study. The information loss rate(ILR), an index based on the information entropy, seems can be used to select optimal DM for each SCV. However, the ILR fails to show the actual influence of discretization because such index only considers the total amount of information of the discretized variables departing from the original SCV. Facing this issue, we propose an index, information change rate(ICR), that focuses on the changed amount of information due to the discretization based on each cell, enabling the identification of the optimal DM. We develop a case study with Random Forest(training/testing ratio of 7 : 3) to assess flood susceptibility in Wanan County, China.The area under the curve-based and susceptibility maps-based approaches were presented to compare the ILR and ICR. The results show the ICR-based optimal DMs are more rational than the ILR-based ones in both cases. Moreover, we observed the ILR values are unnaturally small(<1%), whereas the ICR values are obviously more in line with general recognition(usually 10%–30%). The above results all demonstrate the superiority of the ICR. We consider this study fills up the existing research gaps, improving the MLbased natural hazard susceptibility assessments. 展开更多
关键词 Machine learning Natural hazards Information change rate Discretization method
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Adaptive Wall-Based Attachment Ventilation:A Comparative Study on Its Effectiveness in Airborne Infection Isolation Rooms with Negative Pressure 被引量:2
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作者 Ying Zhang Ou Han +4 位作者 Angui Li Li’an Hou Thomas Olofsson Linhua Zhang Wenjun Lei 《Engineering》 SCIE EI 2022年第1期130-137,共8页
The transmission of coronavirus disease 2019(COVID-19)has presented challenges for the control of the indoor environment of isolation wards.Scientific air distribution design and operation management are crucial to en... The transmission of coronavirus disease 2019(COVID-19)has presented challenges for the control of the indoor environment of isolation wards.Scientific air distribution design and operation management are crucial to ensure the environmental safety of medical staff.This paper proposes the application of adaptive wall-based attachment ventilation and evaluates this air supply mode based on contaminants dispersion,removal efficiency,thermal comfort,and operating expense.Adaptive wall-based attachment ventilation provides a direct supply of fresh air to the occupied zone.In comparison with a ceiling air supply or upper sidewall air supply,adaptive wall-based attachment ventilation results in a 15%–47%lower average concentration of contaminants,for a continual release of contaminants at the same air changes per hour(ACH;10 h^(-1)).The contaminant removal efficiency of complete mixing ventilation cannot exceed 1.For adaptive wall-based attachment ventilation,the contaminant removal efficiency is an exponential function of the ACH.Compared with the ceiling air supply mode or upper sidewall air supply mode,adaptive wall-based attachment ventilation achieves a similar thermal comfort level(predicted mean vote(PMV)of0.1–0.4;draught rate of 2.5%–6.7%)and a similar performance in removing contaminants,but has a lower ACH and uses less energy. 展开更多
关键词 Ventilation efficiency Air change rate COVID-19 Attachment ventilation Air distribution Isolation ward
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Strong dependency of lithium diffusion on mechanical constraints in high-capacity Li-ion battery electrodes 被引量:2
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作者 Yi-Fan Gao Min Zhou 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2012年第4期1068-1077,共10页
The effect of external constraints on Li diffusion in high-capacity Li-ion battery electrodes is investigated using a coupled finite deformation theory. It is found that thinfilm electrodes on rigid substrates experie... The effect of external constraints on Li diffusion in high-capacity Li-ion battery electrodes is investigated using a coupled finite deformation theory. It is found that thinfilm electrodes on rigid substrates experience much slower diffusion rates compared with free-standing films with the same material properties and geometric dimensions. More importantly, the study reveals that mechanical driving forces tend to retard diffusion in highly-constrained thin films when lithiation-induced softening is considered, in contrast to the fact that mechanical driving forces always enhance diffusion when deformation is fully elastic. The results provide further proof that nano-particles are a better design option for nextgeneration alloy-based electrodes compared with thin films. 展开更多
关键词 Li-ion battery - Inelastic flow Lithiation in- duced softening Changing rate
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Fast frequency response of inverter-based resources and its impact on system frequency characteristics 被引量:2
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作者 Lining Su Xiaohui Qin +3 位作者 Shang Zhang Yantao Zhang Yilang Jiang Yi Han 《Global Energy Interconnection》 2020年第5期475-485,共11页
The inertia response and primary frequency regulation capability of synchronous grids are declining owing to the increasing penetration of inverter-based resources. The fast frequency response(FFR) of inverter-based r... The inertia response and primary frequency regulation capability of synchronous grids are declining owing to the increasing penetration of inverter-based resources. The fast frequency response(FFR) of inverter-based resources is an important mitigation option for maintaining grid security under the conditions of low inertia and insufficient primary frequency response capability. However, the understanding and technical characteristics of the FFR of inverter-based resources are still unclear. Aiming at solving the aforementioned problems, this paper proposes a definition for FFR based on the impact mechanism of FFR on system frequency. The performance requirements of FFR are clarified. Then, the effects of FFR on system frequency characteristics are further analyzed based on steady-state frequency deviation, the initial rate of change of frequency, and the maximum transient frequency deviation. Finally, the system requirements for FFR and its application effects are verified by simulating an actual bulk power grid, providing technical support for subsequent engineering application. 展开更多
关键词 Fast frequency response Rate of change of frequency Frequency deviation ROCOF-based FFR Deviation-based FFR
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Energy saving effect of building envelope in summer 被引量:1
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作者 王厚华 郭锐 肖秋连 《Journal of Central South University》 SCIE EI CAS 2012年第5期1370-1376,共7页
To explore the energy saving effect of building envelope, the experiments were carried out through a comparison of basic cubicle in summer. Experiments show that if energy efficiency measures are applied only in the e... To explore the energy saving effect of building envelope, the experiments were carried out through a comparison of basic cubicle in summer. Experiments show that if energy efficiency measures are applied only in the external walls and windows, the energy saving cubicles have an average energy efficiency ratio of 27.75% and 27.05% when the air change rates are 1.1 and 1.4 h-1 in summer, with both values being over the standard target value by 25%. And the indoor air temperature of the energy saving cubicle is below that of the basic cubicle. The daily mean temperature difference between the interior surface of insulation wall and no insulation reaches 1.47℃, and the mean temperature difference is up to 8.52℃ between the interior surface and exterior surface of insulating glass and single glass. The two cubicles were simulated for energy consumption using VisualDOE4.0 software under real weather conditions in summer. The results show that the mean deviation is 10.02% between experimental and simulated energy efficiency ratio. The correctness and validity of simulation results of the VisualDOE4.0 software are proved. 展开更多
关键词 building energy conservation energy efficiency rate thermal performance air change rate
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Variations of the Earth's rotation rate and cyclic processes in geodynamics 被引量:1
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作者 B.W. Levin E.V. Sasorova +3 位作者 G.M. Steblov A.V. Domanski A.S. Prytkov E.N. Tsyba 《Geodesy and Geodynamics》 2017年第3期206-212,共7页
The authors analyzed the relationship between variations of the Earth's rotation rate and the geodynamic processes within the Earth's body, including seismic activity, The rotation rate of a planet determines its un... The authors analyzed the relationship between variations of the Earth's rotation rate and the geodynamic processes within the Earth's body, including seismic activity, The rotation rate of a planet determines its uniaxial compression along the axis of rotation and the areas of various surface elements of the body. The Earth's ellipticity variations, caused naturally by the rotation rate variations, are manifested in vertical components of precise GPS measurements. Comparative analysis of these variations is considered in view of modern theoretical ideas concerning the Earth's figure. The results justify further research that is of interest for improvement of space svstems and technologiesi. 展开更多
关键词 Earth's rotation rate Earth's ellipticity changes in the planet's figure Seismic activity Pulsations of the vertical components of GPS measurements
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