生命科学文摘数据库(BIOSIS Previews,BP)是著名生物学信息检索工具,是科技人员获取生命科学相关信息的重要资源,同时,它也是有效的研究工具。然而,大多数科研人员及信息用户对它的了解和认识不够深入,使很多功能没有得到充分、有效地...生命科学文摘数据库(BIOSIS Previews,BP)是著名生物学信息检索工具,是科技人员获取生命科学相关信息的重要资源,同时,它也是有效的研究工具。然而,大多数科研人员及信息用户对它的了解和认识不够深入,使很多功能没有得到充分、有效地利用。本文对基于ISI Web of Knowledge新检索平台BP数据库的特点、结构及各种功能进行了详细地描述和系统地介绍。可指导研究人员使用数据库,可帮助信息咨询人员和文检课教师了解数据库。展开更多
This paper focuses on the application of H_∞preview control in automatic carrier landing system(ACLS)for carrier-based aircraft.Due to the mutual movement between aircraft and carrier,the landing process becomes cons...This paper focuses on the application of H_∞preview control in automatic carrier landing system(ACLS)for carrier-based aircraft.Due to the mutual movement between aircraft and carrier,the landing process becomes considerably more challenging compared to a conventional runway landing.ACLS systems mitigate this by predicting deck motion and generating ideal glide slope path for tracking.Although,this predicted glide slope information is available in advance,conventional control structures are still unable to use this future information.H_∞preview control has the ability to utilize this future information for improving tracking response and disturbance rejection.The process of incorporating preview information into ACLS framework and synthesizing the H_∞preview controller is presented.The methodology is verified using the example of F/A-18 automatic carrier landing problem and results are presented.展开更多
For carrier-based unmanned aerial vehicles(UAVs),one of the important problems is the design of an automatic carrier landing system(ACLS)that would enable the UAVs to accomplish autolanding on the aircraft carrier.How...For carrier-based unmanned aerial vehicles(UAVs),one of the important problems is the design of an automatic carrier landing system(ACLS)that would enable the UAVs to accomplish autolanding on the aircraft carrier.However,due to the movements of the flight deck with six degree-of-freedom,the autolanding becomes sophisticated.To solve this problem,an accurate and effective ACLS is developed,which is composed of an optimal preview control based flight control system and a Kalman filter based deck motion predictor.The preview control fuses the future information of the reference glide slope to improve landing precision.The reference glide slope is normally a straight line.However,the deck motion will change the position of the ideal landing point,and tracking the ideal straight glide slope may cause landing failure.Therefore,the predictive deck motion information from the deck motion predictor is used to correct the reference glide slope,which decreases the dispersion around the desired landing point.Finally,simulations are carried out to verify the performance of the designed ACLS based on a nonlinear UAV model.展开更多
This paper proposes a static-output-feedback based robust fuzzy wheelbase preview control algorithm for uncertain active suspensions with time delay and finite frequency constraint.Firstly,a Takagi-Sugeno(T-S)fuzzy au...This paper proposes a static-output-feedback based robust fuzzy wheelbase preview control algorithm for uncertain active suspensions with time delay and finite frequency constraint.Firstly,a Takagi-Sugeno(T-S)fuzzy augmented model is established to formulate the half-car active suspension system with consideration of time delay,sprung mass variation and wheelbase preview information.Secondly,in view of the resonation between human’s organs and vertical vibrations in the frequency range of 4–8 Hz,a finite frequency control criterion in terms of H∞norm is developed to improve ride comfort.Meanwhile,other mechanical constraints are also considered and satisfied via generalized H2 norm.Thirdly,in order to maintain the feasibility of the controller despite of some state variables are not online-measured,a two stage approach is adopted to derive a static output feedback controller.Finally,numerical simulation results illustrate the excellent performance of the proposed controller.展开更多
Carrier-based aircraft carrier landing is a special kind of tracking control problem and not suitable for classical control methods,which may miss the desired performance or result in overdesign.Therefore,we present a...Carrier-based aircraft carrier landing is a special kind of tracking control problem and not suitable for classical control methods,which may miss the desired performance or result in overdesign.Therefore,we present an optimal preview control for automatic carrier landing system(ACLS)by using state information of system,as well as future reference information,which can avoid the shortcomings of classical control methods.Since the flight performance of carrier-based aircraft is disturbed by air wake when the aircraft flies near the area of carrier stern,we design a disturbance rejection strategy to ensure that aircraft track the glide path with high precision and robustness.Further,carrier-based aircraft is a complex nonlinear system.However,the nonlinear model of carrier-based aircraft can be linearized at equilibrium landing state and decoupled into the longitudinal model and the lateral model.Therefore,an optimal preview control system is designed.The simulation results of a carrier-based aircraft show that the optimal preview control system can effectively suppress air wake.Tracking accuracy of optimal preview controller is higher than that of the proportional integral differential(PID)control system.展开更多
目的探讨数字乳腺三维断层融合摄影(Digital Breast Tomosynthesis,DBT)结合二维图像(V-preview)的临床应用价值。方法回顾性分析2016年3月至2020年3月于我院行DBT与全数字化乳腺X线摄影(Full-Field Digital Mammography,FFDM)的患者16...目的探讨数字乳腺三维断层融合摄影(Digital Breast Tomosynthesis,DBT)结合二维图像(V-preview)的临床应用价值。方法回顾性分析2016年3月至2020年3月于我院行DBT与全数字化乳腺X线摄影(Full-Field Digital Mammography,FFDM)的患者160例的临床资料,其中非致密型乳腺腺体患者80例,致密型乳腺腺体患者80例。比较不同乳腺腺体分型下,DBT结合V-preview与DBT结合FFDM两种检查模式的诊断效能及辐射剂量差异。结果非致密型乳腺患者中,两种检查模式的敏感度、特异度、准确度差异无统计学意义(P>0.05),但辐射剂量差异有统计学意义(P<0.001)。在致密型乳腺患者中,两种检查模式的敏感度、特异度和准确度差异无统计学意义(P>0.05),但辐射剂量差异有统计学意义(P<0.001)。结论在不同乳腺腺体分型中,DBT结合V-preview检查模式均可以取得与DBT结合FFDM相同的诊断效能,且辐射剂量更低。DBT结合V-preview可替代DBT结合FFDM检查模式。展开更多
Previous studies have confirmed in simulation and experiment that an improved control performance can be obtained when the optimal preview control method was applied to an active suspension system for a quarter car mo...Previous studies have confirmed in simulation and experiment that an improved control performance can be obtained when the optimal preview control method was applied to an active suspension system for a quarter car model. In order to investigate the effectiveness not only in riding comfort but also in road handling, an half car model with the hydro pneumatic active suspension system is proposed in this study. Whole preview control method and partial preview control method, in which the road information detected by the front wheel is sent to the controller to decide the input to rear suspension, are taken into design of the active suspension control system. Results of numerical simulation show that satisfactory control efficiency could be achieved in both whole preview control and partial preview control. The comparison of results suggests that whole preview control method can provide better system performance, but the partial preview control method is superior due to its lower cost.展开更多
A valid preview control technique is presented for processing servo systemswith input delay based on extended error systems with input delay. The technique usesthe concept of error systems, establishes extended error ...A valid preview control technique is presented for processing servo systemswith input delay based on extended error systems with input delay. The technique usesthe concept of error systems, establishes extended error systems with input delay and de-rives preview control laws based on minimization of evaluation function. Finally, simula-tion is done on linear direct current motor without brush. The results reveal that the tech-nique proposed herein is valid for improving performance of servo systems.展开更多
An optimal preview method is applied to the design of terrain following controller for cruise missile. In this method, tracking errors and control increments are both considered in the quadratic cost function. Integra...An optimal preview method is applied to the design of terrain following controller for cruise missile. In this method, tracking errors and control increments are both considered in the quadratic cost function. Integrating the general optimal servo system with a preview feedforward compensation that feeds forward future command and future disturbance produces an optimal preview servo system. In the terrain following system, the flight altitude of the cruise missile is a command signal, and its future information can be known apriori. Hence, we have designed a terrain following controller with a basic state feedback and a feedforward compensation for future altitude information. Simulation results show that the performance of the terrain following system with such an optimal preview controller has been improved dramatically.展开更多
The conference,which is organized by The Chinese Society of Metals,is being activelysupported by the following co-sponsors:ASM INTERNATIONAL(USA),AssociacaoBrasileira De Metals(Brazil),Association Technique de la Side...The conference,which is organized by The Chinese Society of Metals,is being activelysupported by the following co-sponsors:ASM INTERNATIONAL(USA),AssociacaoBrasileira De Metals(Brazil),Association Technique de la Siderurgie Francaise(France),Associazione Italiana di Metallurgia(Italy),Societe Francaise de Metallurgie(France),The Indian Institute of Metals,The Institute of Metals,(UK),The Iron and Steel Instituteof Japan,The Iron and Steel Society of AIME(USA),The Japan Institute of Metals,The Minerals,Metals,and Materials Society(USA),Verein Deutscher Eisenhüttenleute(F.R.Germany),Institute of Metals and Materials Australia.展开更多
文摘生命科学文摘数据库(BIOSIS Previews,BP)是著名生物学信息检索工具,是科技人员获取生命科学相关信息的重要资源,同时,它也是有效的研究工具。然而,大多数科研人员及信息用户对它的了解和认识不够深入,使很多功能没有得到充分、有效地利用。本文对基于ISI Web of Knowledge新检索平台BP数据库的特点、结构及各种功能进行了详细地描述和系统地介绍。可指导研究人员使用数据库,可帮助信息咨询人员和文检课教师了解数据库。
基金supported by the National Natural Science Foundation of China (Nos.61973158, 61304223, 61673209)the Aeronautical Science Foundation (NO.2016ZA52009)the Fundamental Research Funds for the Central Universities (Nos.NS2017015, NJ20170005)
文摘This paper focuses on the application of H_∞preview control in automatic carrier landing system(ACLS)for carrier-based aircraft.Due to the mutual movement between aircraft and carrier,the landing process becomes considerably more challenging compared to a conventional runway landing.ACLS systems mitigate this by predicting deck motion and generating ideal glide slope path for tracking.Although,this predicted glide slope information is available in advance,conventional control structures are still unable to use this future information.H_∞preview control has the ability to utilize this future information for improving tracking response and disturbance rejection.The process of incorporating preview information into ACLS framework and synthesizing the H_∞preview controller is presented.The methodology is verified using the example of F/A-18 automatic carrier landing problem and results are presented.
基金supported in part by the National Natural Science Foundations of China(Nos.61304223,61673209,61533008)the Aeronautical Science Foundation(No.2016ZA 52009)the Fundamental Research Funds for the Central Universities(No.NJ20160026)
文摘For carrier-based unmanned aerial vehicles(UAVs),one of the important problems is the design of an automatic carrier landing system(ACLS)that would enable the UAVs to accomplish autolanding on the aircraft carrier.However,due to the movements of the flight deck with six degree-of-freedom,the autolanding becomes sophisticated.To solve this problem,an accurate and effective ACLS is developed,which is composed of an optimal preview control based flight control system and a Kalman filter based deck motion predictor.The preview control fuses the future information of the reference glide slope to improve landing precision.The reference glide slope is normally a straight line.However,the deck motion will change the position of the ideal landing point,and tracking the ideal straight glide slope may cause landing failure.Therefore,the predictive deck motion information from the deck motion predictor is used to correct the reference glide slope,which decreases the dispersion around the desired landing point.Finally,simulations are carried out to verify the performance of the designed ACLS based on a nonlinear UAV model.
基金supported by the National Natural Science Foundation of China(51705084)the Natural Science Foundation of Guangdong Province(2018A030313999,2019A1515011602)+6 种基金the Fundamental Research Funds for the Central Universities(N2003032)the Opening Project of Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced ManufacturingSouth China University of Technology(2019kfkt06,2020kfkt05)the Research Grants of the University of Macao(MYRG2019-00028-FST)Guangdong Regular Institutions of Characteristic Innovation Project(2017KTSCX176)Key Laboratory of Robotics and Intelligent Equipment of Guangdong Regular Institutions of Higher Education(2017KSYS009)the National Key Research and Development Program of China(2017YFB1300200,2017YFB1300203)。
文摘This paper proposes a static-output-feedback based robust fuzzy wheelbase preview control algorithm for uncertain active suspensions with time delay and finite frequency constraint.Firstly,a Takagi-Sugeno(T-S)fuzzy augmented model is established to formulate the half-car active suspension system with consideration of time delay,sprung mass variation and wheelbase preview information.Secondly,in view of the resonation between human’s organs and vertical vibrations in the frequency range of 4–8 Hz,a finite frequency control criterion in terms of H∞norm is developed to improve ride comfort.Meanwhile,other mechanical constraints are also considered and satisfied via generalized H2 norm.Thirdly,in order to maintain the feasibility of the controller despite of some state variables are not online-measured,a two stage approach is adopted to derive a static output feedback controller.Finally,numerical simulation results illustrate the excellent performance of the proposed controller.
基金supported in part by the National Natural Science Foundation of China(Nos.61741313,61304223,61673209,61533008)the Jiangsu Six Peak of Talents program(No.KTHY-027)+1 种基金the Aeronautical Science Foundation(No.2016ZA 52009)the Fundamental Research Funds for the Central Universities(Nos.NJ20160026,NS2017015)
文摘Carrier-based aircraft carrier landing is a special kind of tracking control problem and not suitable for classical control methods,which may miss the desired performance or result in overdesign.Therefore,we present an optimal preview control for automatic carrier landing system(ACLS)by using state information of system,as well as future reference information,which can avoid the shortcomings of classical control methods.Since the flight performance of carrier-based aircraft is disturbed by air wake when the aircraft flies near the area of carrier stern,we design a disturbance rejection strategy to ensure that aircraft track the glide path with high precision and robustness.Further,carrier-based aircraft is a complex nonlinear system.However,the nonlinear model of carrier-based aircraft can be linearized at equilibrium landing state and decoupled into the longitudinal model and the lateral model.Therefore,an optimal preview control system is designed.The simulation results of a carrier-based aircraft show that the optimal preview control system can effectively suppress air wake.Tracking accuracy of optimal preview controller is higher than that of the proportional integral differential(PID)control system.
文摘目的探讨数字乳腺三维断层融合摄影(Digital Breast Tomosynthesis,DBT)结合二维图像(V-preview)的临床应用价值。方法回顾性分析2016年3月至2020年3月于我院行DBT与全数字化乳腺X线摄影(Full-Field Digital Mammography,FFDM)的患者160例的临床资料,其中非致密型乳腺腺体患者80例,致密型乳腺腺体患者80例。比较不同乳腺腺体分型下,DBT结合V-preview与DBT结合FFDM两种检查模式的诊断效能及辐射剂量差异。结果非致密型乳腺患者中,两种检查模式的敏感度、特异度、准确度差异无统计学意义(P>0.05),但辐射剂量差异有统计学意义(P<0.001)。在致密型乳腺患者中,两种检查模式的敏感度、特异度和准确度差异无统计学意义(P>0.05),但辐射剂量差异有统计学意义(P<0.001)。结论在不同乳腺腺体分型中,DBT结合V-preview检查模式均可以取得与DBT结合FFDM相同的诊断效能,且辐射剂量更低。DBT结合V-preview可替代DBT结合FFDM检查模式。
文摘Previous studies have confirmed in simulation and experiment that an improved control performance can be obtained when the optimal preview control method was applied to an active suspension system for a quarter car model. In order to investigate the effectiveness not only in riding comfort but also in road handling, an half car model with the hydro pneumatic active suspension system is proposed in this study. Whole preview control method and partial preview control method, in which the road information detected by the front wheel is sent to the controller to decide the input to rear suspension, are taken into design of the active suspension control system. Results of numerical simulation show that satisfactory control efficiency could be achieved in both whole preview control and partial preview control. The comparison of results suggests that whole preview control method can provide better system performance, but the partial preview control method is superior due to its lower cost.
文摘A valid preview control technique is presented for processing servo systemswith input delay based on extended error systems with input delay. The technique usesthe concept of error systems, establishes extended error systems with input delay and de-rives preview control laws based on minimization of evaluation function. Finally, simula-tion is done on linear direct current motor without brush. The results reveal that the tech-nique proposed herein is valid for improving performance of servo systems.
文摘An optimal preview method is applied to the design of terrain following controller for cruise missile. In this method, tracking errors and control increments are both considered in the quadratic cost function. Integrating the general optimal servo system with a preview feedforward compensation that feeds forward future command and future disturbance produces an optimal preview servo system. In the terrain following system, the flight altitude of the cruise missile is a command signal, and its future information can be known apriori. Hence, we have designed a terrain following controller with a basic state feedback and a feedforward compensation for future altitude information. Simulation results show that the performance of the terrain following system with such an optimal preview controller has been improved dramatically.
文摘The conference,which is organized by The Chinese Society of Metals,is being activelysupported by the following co-sponsors:ASM INTERNATIONAL(USA),AssociacaoBrasileira De Metals(Brazil),Association Technique de la Siderurgie Francaise(France),Associazione Italiana di Metallurgia(Italy),Societe Francaise de Metallurgie(France),The Indian Institute of Metals,The Institute of Metals,(UK),The Iron and Steel Instituteof Japan,The Iron and Steel Society of AIME(USA),The Japan Institute of Metals,The Minerals,Metals,and Materials Society(USA),Verein Deutscher Eisenhüttenleute(F.R.Germany),Institute of Metals and Materials Australia.
