BACKGROUND Among the rapidly developing single-incision laparoscopic cholecystectomy(LC)techniques,transumbilical single-incision LC is increasingly replacing the traditional LC,with advantages of minimal invasion,sli...BACKGROUND Among the rapidly developing single-incision laparoscopic cholecystectomy(LC)techniques,transumbilical single-incision LC is increasingly replacing the traditional LC,with advantages of minimal invasion,slight postoperative pain,faster recovery.Despite the advantages mentioned above,the currently available specialized single-port laparoscopic instruments are hindered by high costs and limited applications,challenging their widespread use in medical facilities.AIM To design a two-point lifting/retracting(TPLR)technique for transumbilical single-port LC(TUSPLC)based on the anatomical features of the Calot's triangle(or cystohepatic triangle)and investigate its surgical feasibility.METHODS The clinical data of 103 patients who underwent TUSPLC utilizing the TPLR technique in the Department of Hepatobiliary Surgery at our hospital between June 2023 and June 2024 were retrospectively analyzed.The patient cohort included 82 cases of cholelithiasis,11 cases of gallbladder polyps,6 cases of concurrent gallstones and polyps,and 4 cases of gallbladder adenomyomatosis.RESULTS All the surgical procedures were conducted using standard laparoscopic instruments.Surgery was successful in 98(95.14%)patients using the TPLR method,which effectively exposed the Calot's triangle during surgery.The operative time ranged from 35 to 70 minutes,with an average of 42.4±26.8 minutes.In 3 cases,an additional operative port was required below the xiphoid process,and 2 cases were converted to conventional three-port LC.No complications such as abdominal pain,fever,bile leakage,hemorrhage,or incisional infection were noted postoperatively.No discernible surgical scars were observed at the 2-week postoperative reexamination.Additionally,a 3-month follow-up period revealed no complications.CONCLUSION The TPLR technique,developed based on the anatomical features of the Calot's triangle,facilitates exposure of the Calot's triangle during surgery.It is a simple,safe,feasible,and cost-effective method,and a promising approach for single-port LC.展开更多
Effective management of water resources,especially groundwater,is crucial and requires a precise understanding of aquifer characteristics,imposed stresses,and the groundwater balance.Simulation-optimization models pla...Effective management of water resources,especially groundwater,is crucial and requires a precise understanding of aquifer characteristics,imposed stresses,and the groundwater balance.Simulation-optimization models plays a vital role in guiding planners toword sustainable long-term aquifer exploita-tion.This study simulated monthly water table variations in the Kashan Plain over a ten-year period from 2008 to 2019 across 125 stress periods using the GMS model.The model was calibrated for both steady-state and transient conditions for the 2008–2016 period and validated for the 2016–2019 period.Results indicated a 4.4 m decline in groundwater levels over the 10-year study period.Given the plain's location in a arid climatic zone with limited effective precipitation for aquifer recharge,the study focused on ground-water extraction management.A modified two-point hedging policy was employed as a solution to mitigate critical groundwater depletion,reducing the annual drawdown rate from 0.44 m to 0.31 m and conserving 255 million cubic meters(mcm)of water annually.Although this approach slightly decreased reliability(i.e.the number of months meeting full water demands),it effectively minimized the risk of severe droughts and irreparable damages.This policy offers managers a dynamical and intelligent tool for regulating groundwater extraction,balancing aquifer sustainability with agricultural and urban water requirements.展开更多
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
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 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
Several existence theorems were established for a nonlinear fourth-order two-point boundary value problem with second derivative by using Leray-Schauder fixed point theorem, equivalent norm and technique on system of ...Several existence theorems were established for a nonlinear fourth-order two-point boundary value problem with second derivative by using Leray-Schauder fixed point theorem, equivalent norm and technique on system of integral equations. The main conditions of our results are local. In other words, the existence of the solution can be determined by considering the height of the nonlinear term on a bounded set. This class of problems usually describes the equilibrium state of an elastic beam which is simply supported at both ends.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
The unsatisfied surface quality seriously impedes the wide application of incremental sheet forming(ISF)in industrial field.As a novel approach,the interpolator method is a promising strategy to enhance the surface qu...The unsatisfied surface quality seriously impedes the wide application of incremental sheet forming(ISF)in industrial field.As a novel approach,the interpolator method is a promising strategy to enhance the surface quality in ISF.However,the mechanism for the improvement of surface quality and the influence of interpolator properties on surface roughness are not well understood.In this paper,the influences of process variables(i.e.tool diameter,step size and thickness of interpolators)on the forming process(e.g.surface roughness,forming force and geometric error)are investigated through a systematic experimental approach of central composite design(CCD)in two-point incremental sheet forming(TPIF).It is obtained that the increase in thickness of interpolators decreases the surface roughness in direction vertical to the tool path while increases the surface roughness in direction horizontal to the tool path.Nevertheless,the combined influence between thickness of interpolators and process parameters(tool diameter and step size)is limited.Meanwhile,the placement of interpolator has little influence on the effective forming force of blank.In addition,the geometric error enlarges with the increase of step size and thickness of interpolator while decreases firstly and then increase with an increase in tool diameter.Finally,the influencing mechanism of the interpolator method on surface quality can be attributed to the decrease of thecontact pressure due to the increase of contact area with the unchanged contact force.Meanwhile,the interpolator method eliminates the sliding friction on the surface of blank due to the stable relative position between the blank and the interpolator.展开更多
The existence of nondecreasing positive solutions for the nonlinear third-order twopoint boundary value problem u′″（t） ＋ q（t）f（t,u（t）,u′（t）） = 0, 0 〈 t 〈 1, u（0） = u″（0） = u′（1） = 0 is studied....The existence of nondecreasing positive solutions for the nonlinear third-order twopoint boundary value problem u′″（t） ＋ q（t）f（t,u（t）,u′（t）） = 0, 0 〈 t 〈 1, u（0） = u″（0） = u′（1） = 0 is studied. The iterative schemes for approximating the solutions are obtained by applying a monotone iterative method.展开更多
文摘2025年6月10日,科睿唯安(Clarivate Analytics)来函通知,《临床肝胆病杂志》被Web of Science合集中的BIOSIS Citation Index(生命科学引文索引,BCI)、BIOSIS Previews(生命科学信息预览,BP)、Biological Abstracts(生命科学文摘,BA)等3个数据库收录。BCI是生命科学领域内容最权威的引文索引数据库之一,不仅收录BP数据库全部期刊信息,还包含Web of Science未索引的原始研究报告以及重要研究文献的参考文献数据等。
文摘BACKGROUND Among the rapidly developing single-incision laparoscopic cholecystectomy(LC)techniques,transumbilical single-incision LC is increasingly replacing the traditional LC,with advantages of minimal invasion,slight postoperative pain,faster recovery.Despite the advantages mentioned above,the currently available specialized single-port laparoscopic instruments are hindered by high costs and limited applications,challenging their widespread use in medical facilities.AIM To design a two-point lifting/retracting(TPLR)technique for transumbilical single-port LC(TUSPLC)based on the anatomical features of the Calot's triangle(or cystohepatic triangle)and investigate its surgical feasibility.METHODS The clinical data of 103 patients who underwent TUSPLC utilizing the TPLR technique in the Department of Hepatobiliary Surgery at our hospital between June 2023 and June 2024 were retrospectively analyzed.The patient cohort included 82 cases of cholelithiasis,11 cases of gallbladder polyps,6 cases of concurrent gallstones and polyps,and 4 cases of gallbladder adenomyomatosis.RESULTS All the surgical procedures were conducted using standard laparoscopic instruments.Surgery was successful in 98(95.14%)patients using the TPLR method,which effectively exposed the Calot's triangle during surgery.The operative time ranged from 35 to 70 minutes,with an average of 42.4±26.8 minutes.In 3 cases,an additional operative port was required below the xiphoid process,and 2 cases were converted to conventional three-port LC.No complications such as abdominal pain,fever,bile leakage,hemorrhage,or incisional infection were noted postoperatively.No discernible surgical scars were observed at the 2-week postoperative reexamination.Additionally,a 3-month follow-up period revealed no complications.CONCLUSION The TPLR technique,developed based on the anatomical features of the Calot's triangle,facilitates exposure of the Calot's triangle during surgery.It is a simple,safe,feasible,and cost-effective method,and a promising approach for single-port LC.
文摘Effective management of water resources,especially groundwater,is crucial and requires a precise understanding of aquifer characteristics,imposed stresses,and the groundwater balance.Simulation-optimization models plays a vital role in guiding planners toword sustainable long-term aquifer exploita-tion.This study simulated monthly water table variations in the Kashan Plain over a ten-year period from 2008 to 2019 across 125 stress periods using the GMS model.The model was calibrated for both steady-state and transient conditions for the 2008–2016 period and validated for the 2016–2019 period.Results indicated a 4.4 m decline in groundwater levels over the 10-year study period.Given the plain's location in a arid climatic zone with limited effective precipitation for aquifer recharge,the study focused on ground-water extraction management.A modified two-point hedging policy was employed as a solution to mitigate critical groundwater depletion,reducing the annual drawdown rate from 0.44 m to 0.31 m and conserving 255 million cubic meters(mcm)of water annually.Although this approach slightly decreased reliability(i.e.the number of months meeting full water demands),it effectively minimized the risk of severe droughts and irreparable damages.This policy offers managers a dynamical and intelligent tool for regulating groundwater extraction,balancing aquifer sustainability with agricultural and urban water requirements.
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 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 (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.
文摘Several existence theorems were established for a nonlinear fourth-order two-point boundary value problem with second derivative by using Leray-Schauder fixed point theorem, equivalent norm and technique on system of integral equations. The main conditions of our results are local. In other words, the existence of the solution can be determined by considering the height of the nonlinear term on a bounded set. This class of problems usually describes the equilibrium state of an elastic beam which is simply supported at both ends.
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.
基金support from the National Natural Science Foundation of China(51575028)National Natural Science Foundation of China(51605258)the Fundamental Research Funds for the Central Universities of China(YWF-18-BJ-J-75)。
文摘The unsatisfied surface quality seriously impedes the wide application of incremental sheet forming(ISF)in industrial field.As a novel approach,the interpolator method is a promising strategy to enhance the surface quality in ISF.However,the mechanism for the improvement of surface quality and the influence of interpolator properties on surface roughness are not well understood.In this paper,the influences of process variables(i.e.tool diameter,step size and thickness of interpolators)on the forming process(e.g.surface roughness,forming force and geometric error)are investigated through a systematic experimental approach of central composite design(CCD)in two-point incremental sheet forming(TPIF).It is obtained that the increase in thickness of interpolators decreases the surface roughness in direction vertical to the tool path while increases the surface roughness in direction horizontal to the tool path.Nevertheless,the combined influence between thickness of interpolators and process parameters(tool diameter and step size)is limited.Meanwhile,the placement of interpolator has little influence on the effective forming force of blank.In addition,the geometric error enlarges with the increase of step size and thickness of interpolator while decreases firstly and then increase with an increase in tool diameter.Finally,the influencing mechanism of the interpolator method on surface quality can be attributed to the decrease of thecontact pressure due to the increase of contact area with the unchanged contact force.Meanwhile,the interpolator method eliminates the sliding friction on the surface of blank due to the stable relative position between the blank and the interpolator.
基金Supported by the Natural Science Foundation of Zhejiang Province (Y605144)the XNF of Zhejiang University of Media and Communications (XN080012008034)
文摘The existence of nondecreasing positive solutions for the nonlinear third-order twopoint boundary value problem u′″（t） ＋ q（t）f（t,u（t）,u′（t）） = 0, 0 〈 t 〈 1, u（0） = u″（0） = u′（1） = 0 is studied. The iterative schemes for approximating the solutions are obtained by applying a monotone iterative method.
