Electromagnetic technology used in logging while drilling(LWD) provides the resistivity distribution around a borehole within a range of several tens of meters.However,a blind zone appears in front of the drill bit wh...Electromagnetic technology used in logging while drilling(LWD) provides the resistivity distribution around a borehole within a range of several tens of meters.However,a blind zone appears in front of the drill bit when operating in high-angle wells,limiting the ability to detect formations ahead of the drill bit.Look-ahead technology addresses this issue and substantially enhances the proactive capability of geological directional drilling.In this study,we examine the detection capabilities of various component combinations of magnetic dipole antenna.Based on the sensitivity of each component to the axial information,a coaxial component is selected as a boundary indicator.We investigate the impact of various factors,such as frequency and transmitter and receiver(TR) distance,under different geological models.This study proposes 5 and 20 kHz as appropriate frequencies,and 10-14 and 12-17 m as suitable TR distance combinations.The accuracy of the numerical calculation results is verified via air-sea testing,confirming the instrument's detection capability.A test model that eliminated the influence of environmental factors and seawater depth is developed.The results have demonstrated that the tool can recognize the interface between layers up to 21.6 m ahead.It provides a validation idea for the design of new instruments as well as the validation of detection capabilities.展开更多
With the development of fast communication technology between ego vehicle and other traffic participants,and automated driving technology,there is a big potential in the improvement of energy efficiency of hybrid elec...With the development of fast communication technology between ego vehicle and other traffic participants,and automated driving technology,there is a big potential in the improvement of energy efficiency of hybrid electric vehicles(HEVs).Moreover,the terrain along the driving route is a non-ignorable factor for energy efficiency of HEV running on the hilly streets.This paper proposes a look-ahead horizon-based optimal energy management strategy to jointly improve the efficiencies of powertrain and vehicle for connected and automated HEVs on the road with slope.Firstly,a rule-based framework is developed to guarantee the success of automated driving in the traffic scenario.Then a constrained optimal control problem is formulated to minimize the fuel consumption and the electricity consumption under the satisfaction of inter-vehicular distance constraint between ego vehicle and preceding vehicle.Both speed planning and torque split of hybrid powertrain are provided by the proposed approach.Moreover,the preceding vehicle speed in the look-ahead horizon is predicted by extreme learning machine with real-time data obtained from communication of vehicle-to-everything.The optimal solution is derived through the Pontryagin’s maximum principle.Finally,to verify the effectiveness of the proposed algorithm,a traffic-in-the-loop powertrain platform with data from real world traffic environment is built.It is found that the fuel economy for the proposed energy management strategy improves in average 17.0%in scenarios of different traffic densities,compared to the energy management strategy without prediction of preceding vehicle speed.展开更多
研究多站点传送带给料生产加工站(Conveyor-serviced production station,CSPS)系统的最优控制问题,其优化目标是通过合理选择每个CSPS的Look-ahead控制策略,实现整个系统的工件处理率最大.本文首先根据多Agent系统的反应扩散思想,对每...研究多站点传送带给料生产加工站(Conveyor-serviced production station,CSPS)系统的最优控制问题,其优化目标是通过合理选择每个CSPS的Look-ahead控制策略,实现整个系统的工件处理率最大.本文首先根据多Agent系统的反应扩散思想,对每个Agent的原始性能函数进行改进,引入了具有扩散功能的局域信息交互项(原始项看作具有反应功能);并运用性能势理论,构建一种适用于平均和折扣两种性能准则的Wolf-PHC多Agent学习算法,以求解决策时刻不同步的多站点的协作Look-ahead控制策略.最后,论文通过仿真实验验证了该算法的有效性,学习结果表明,通过性能函数的改进,各工作站的负载平衡性得到改善,整个系统的工件处理率也明显提高.展开更多
Generally complex 3D contours are divided into a lot of continuous small line blocks by CAD/CAM software. When these small line blocks are used in conventional way,machine tool has to stop at the end of one move befor...Generally complex 3D contours are divided into a lot of continuous small line blocks by CAD/CAM software. When these small line blocks are used in conventional way,machine tool has to stop at the end of one move before continuing on to the next to meet accuracy requirement,which results in inefficiency.Look-ahead is an intelligent function that aims at adjusting the feed rate automatically to achieve maximum productivity while maintaining accuracy.By now most researchers just utilize the simplest linear acceleration(ACC)and deceleration(DEC)to deal with look-ahead intelligence.A generalized ACC/DEC ap- proach and corresponding optimal look-ahead algorithm based on dynamic back tracking along a doubly linked list are proposed.An improved rounding strategy for reducing interpolation errors is also presented.By using the proposed techniques,arbitrary velocity profiles that offer look-ahead feature and have the desired ACC/DEC characteristics for movement of a lot of continuous line blocks can be generated efficiently.Both simulations and experiments showed the productivity was dramatically increased without sacri- fice of accuracy.展开更多
To avoid suffering gouge and transient overshooting in high speed cutting machining, a novel parametefized curve interpolator model with velocity look-ahead algorithm is proposed. Based on a prearrangement step interp...To avoid suffering gouge and transient overshooting in high speed cutting machining, a novel parametefized curve interpolator model with velocity look-ahead algorithm is proposed. Based on a prearrangement step interpolation algorithm for parameterized curves and considering high curvature points, parameterized curve tool path is divided into acceleration segments and deceleration segments by look-ahead algorithm. Under condition of characteristics of acceleration and deceleration stored in control system, deceleration before high curvature points and acceleration after high curvature points are realized in real-time in high speed cutting machining. Based on new parameterized curve interpolator model with velocity look-ahead algorithm, a real cubic spline is machined simulativly. The simulation results show that velocity look-ahead algorithm improves velocity changing more smoothly.展开更多
This paper presents a new deep-reading logging-while-drilling electromagnetic(EM)logging method to detect bed boundaries ahead of bit.Unlike all existing EM logging approaches,the new method is based on the scattered ...This paper presents a new deep-reading logging-while-drilling electromagnetic(EM)logging method to detect bed boundaries ahead of bit.Unlike all existing EM logging approaches,the new method is based on the scattered electric field radiated by a magnetic dipole antenna.By analyzing the characteristics of electric tensor responses in layered formations,optimal look-ahead electric component is selected.The selected scattered field contributes to a large portion of the total field and is strongly sensitive to the boundary position.The measured voltage from the scattered electric component can be tens of times larger than that from the scattered magnetic fields and it attenuates slower.Thus,the detection capability improves significantly.A coaxial open-loop half-circle antenna is then proposed to measure the electric field in logging while drilling environment.A practical tool implementation equipped with two tilted close-loop antennas and two open-loop antennas is further developed for look-ahead application.Numerical results demonstrate that the detection depth of the new look-ahead tool can be up to 40 m under favorable conditions.Compared with current look-ahead logging tools,the new method not only significantly shortens the tool size,but also can recognize the boundary position and azimuth.展开更多
The principle of real-time look-ahead was introduced and analysed. An adaptive parametric curve interpolator with a real-time look-ahead function was developed for non-uniform rational B-spline (NURBS) curves interpol...The principle of real-time look-ahead was introduced and analysed. An adaptive parametric curve interpolator with a real-time look-ahead function was developed for non-uniform rational B-spline (NURBS) curves interpolation, which considering the maximum acceleration/deceleration of the machine tool. In order to deal with the acceleration/deceleration around the feedrate sensitive corners, the look-ahead function was designed and illustrated. It can detect and adjust the feedrate adaptively. With the help of real-time look-ahead, the acceleration/deceleration can be limited to the range of the machine tool capacity. Thus, feedrate fluctuation is reduced. A NURBS curve interpolation experiment was provided to verify the feasibility and advantages of the proposed interpolator with a real-time look-ahead function.展开更多
When a robot is required to machine a complex curved workpiece with high precision and speed,the tool path is typically dispersed into a series of points and transmitted to the robot.The conventional trajectory planni...When a robot is required to machine a complex curved workpiece with high precision and speed,the tool path is typically dispersed into a series of points and transmitted to the robot.The conventional trajectory planning method requires frequent starts and stops at each dispersed point to complete the task.This method not only reduces precision but also causes damage to the motors and robot.A real-time look-ahead algorithm is proposed in this paper to improve precision and minimize damage.The proposed algorithm includes a path-smoothing algorithm,a trajectory planning method,and a bidirectional scanning module.The path-smoothing method inserts a quintic Bezier curve between small adjacent line segments to achieve G^(2)continuity at the junctions.The trajectory planning method utilizes a quartic polynomial and a double-quartic polynomial that can achieve a constant velocity at the velocity limitation.The bidirectional scanning module calculates the velocity at each trajectory planning segment point,simplifying calculation complexity and can be run in real time.The feasibility of the proposed algorithm is verified through simulations and experiments,which can be run in real time.In addition,high machining precision can be achieved by adjusting the relevant parameters.展开更多
With the development of traffic systems, some issues such as traffic jams become more and more serious. Efficient traffic flow theory is needed to guide the overall controlling, organizing and management of traffic sy...With the development of traffic systems, some issues such as traffic jams become more and more serious. Efficient traffic flow theory is needed to guide the overall controlling, organizing and management of traffic systems. On the basis of the cellular automata model and the traffic flow model with look-ahead potential, a new cellular automata traffic flow model with negative exponential weighted look-ahead potential is presented in this paper. By introducing the negative exponential weighting coefficient into the look-ahead potential and endowing the potential of vehicles closer to the driver with a greater coefficient, the modeling process is more suitable for the driver’s random decision-making process which is based on the traffic environment that the driver is facing. The fundamental diagrams for different weighting parameters are obtained by using numerical simulations which show that the negative exponential weighting coefficient has an obvious effect on high density traffic flux. The complex high density non-linear traffic behavior is also reproduced by numerical simulations.展开更多
The increasing penetration of renewable energy resources degrades the frequency stability of power systems.The present work addresses this issue by proposing a look-ahead dispatch model of power systems based on a lin...The increasing penetration of renewable energy resources degrades the frequency stability of power systems.The present work addresses this issue by proposing a look-ahead dispatch model of power systems based on a linear alternating current optimal power flow framework with nonlinear frequency constraints.Meanwhile,the poor efficiency for solving this formulation is addressed by introducing a physics-informed neural network(PINN)to predict key frequency-control parameter values accurately.The PINN ensures that the learned results are applicable to the original physical frequency dynamics model,and applying the predicted parameter values enables the resulting dispatch model to be solved quickly and efficiently using readily available commercial solvers.The feasibility and advantages of the proposed model are demonstrated by the results of numerical computations applied to a modified IEEE 118-bus test system.展开更多
CNC machining plays an important role in mechanical manufacturing.A key issue is to improve the machining feedrate while keeping the machining precision and satisfying the acceleration constraints of the CNC machine.F...CNC machining plays an important role in mechanical manufacturing.A key issue is to improve the machining feedrate while keeping the machining precision and satisfying the acceleration constraints of the CNC machine.For the consecutive micro-line segments interpolation,the velocities at the junction of two segments are the bottlenecks for the machining efficiency.This paper proposes a multi-period turning method to improve the feedrate at the junctions using the linear acceleration and deceleration mode,which utilizes the maximal acceleration capabilities of the NC machine while satisfying the machining precision.A new and more efficient look-ahead method and a feedrate override method are also proposed to boast the global machining speed.The proposed algorithm has been implemented on Blue Sky NC System,and experimented in real material manufacturing.Compared with several existing algorithms,the current algorithm can improve the manufacturing time ranging from 50% to 180%,depending on the machining parameters,and also results in better machining quality.In addition,the algorithm also satisfies the need of real-time interpolation.展开更多
The roll-out of a flexible ramping product provides independent system operators(ISOs)with the ability to address the issues of ramping capacity shortage.ISOs procure flexible ramping capability by committing more gen...The roll-out of a flexible ramping product provides independent system operators(ISOs)with the ability to address the issues of ramping capacity shortage.ISOs procure flexible ramping capability by committing more generating units or reserving a certain amount of headrooms of committed units.In this paper,we raise the concern of the possibility that the procured flexible ramping capability cannot be deployed in realtime operations due to the unit shut-down in a look-ahead commitment(LAC)procedure.As a solution to the issues of ramping capacity shortage,we provide a modified ramping product formulation designed to improve the reliability and reduce the expected operating cost.The trajectories of start-up and shutdown processes are also considered in determining the ramping capability.A new optimization problem is formulated using mixed integer linear programming(MILP)to be readily applied to the practical power system operation.The performance of this proposed method is verified through simulations using a small-scale system and IEEE 118-bus system.The simulation results demonstrate that the proposed method can improve the generation scheduling by alleviating the ramping capacity shortages.展开更多
It is intuitive that allowing a deeper search into a game tree will result in a superior player to one that is restricted in the depth of the search that it is allowed to make. Of course, searching deeper into the tre...It is intuitive that allowing a deeper search into a game tree will result in a superior player to one that is restricted in the depth of the search that it is allowed to make. Of course, searching deeper into the tree comes at increased computational cost and this is one of the trade-offs that has to be considered in developing a tree-based search algorithm. There has been some discussion as to whether the evaluation function, or the depth of the search, is the main contributory factor in the performance of an evolved checkers player. Some previous research has investigated this question （on Chess and Othello）, with differing conclusions. This suggests that different games have different emphases, with respect to these two factors. This paper provides the evidence for evolutionary checkers, and shows that the look-ahead depth （like Chess, perhaps unsurprisingly） is important. This is the first time that such an intensive study has been carried out for evolutionary checkers and given the evidence provided for Chess and Othello this is an important study that provides the evidence for another game. We arrived at our conclusion by evolving various checkers players at different ply depths and by playing them against one another, again at different ply depths. This was combined with the two-move ballot （enabling more games against the evolved players to take place） which provides strong evidence that depth of the look-ahead is important for evolved checkers players.展开更多
基金co-funded by the National Key Research and Development Program of China under Grant (2019YFA0708301)the CAS Project for Young Scientists in Basic Research (Grant No.YSBR-082)Research Instrument and Equipment Development Project of Chinese Academy of Sciences (GJJSTD20210008)。
文摘Electromagnetic technology used in logging while drilling(LWD) provides the resistivity distribution around a borehole within a range of several tens of meters.However,a blind zone appears in front of the drill bit when operating in high-angle wells,limiting the ability to detect formations ahead of the drill bit.Look-ahead technology addresses this issue and substantially enhances the proactive capability of geological directional drilling.In this study,we examine the detection capabilities of various component combinations of magnetic dipole antenna.Based on the sensitivity of each component to the axial information,a coaxial component is selected as a boundary indicator.We investigate the impact of various factors,such as frequency and transmitter and receiver(TR) distance,under different geological models.This study proposes 5 and 20 kHz as appropriate frequencies,and 10-14 and 12-17 m as suitable TR distance combinations.The accuracy of the numerical calculation results is verified via air-sea testing,confirming the instrument's detection capability.A test model that eliminated the influence of environmental factors and seawater depth is developed.The results have demonstrated that the tool can recognize the interface between layers up to 21.6 m ahead.It provides a validation idea for the design of new instruments as well as the validation of detection capabilities.
文摘With the development of fast communication technology between ego vehicle and other traffic participants,and automated driving technology,there is a big potential in the improvement of energy efficiency of hybrid electric vehicles(HEVs).Moreover,the terrain along the driving route is a non-ignorable factor for energy efficiency of HEV running on the hilly streets.This paper proposes a look-ahead horizon-based optimal energy management strategy to jointly improve the efficiencies of powertrain and vehicle for connected and automated HEVs on the road with slope.Firstly,a rule-based framework is developed to guarantee the success of automated driving in the traffic scenario.Then a constrained optimal control problem is formulated to minimize the fuel consumption and the electricity consumption under the satisfaction of inter-vehicular distance constraint between ego vehicle and preceding vehicle.Both speed planning and torque split of hybrid powertrain are provided by the proposed approach.Moreover,the preceding vehicle speed in the look-ahead horizon is predicted by extreme learning machine with real-time data obtained from communication of vehicle-to-everything.The optimal solution is derived through the Pontryagin’s maximum principle.Finally,to verify the effectiveness of the proposed algorithm,a traffic-in-the-loop powertrain platform with data from real world traffic environment is built.It is found that the fuel economy for the proposed energy management strategy improves in average 17.0%in scenarios of different traffic densities,compared to the energy management strategy without prediction of preceding vehicle speed.
文摘研究多站点传送带给料生产加工站(Conveyor-serviced production station,CSPS)系统的最优控制问题,其优化目标是通过合理选择每个CSPS的Look-ahead控制策略,实现整个系统的工件处理率最大.本文首先根据多Agent系统的反应扩散思想,对每个Agent的原始性能函数进行改进,引入了具有扩散功能的局域信息交互项(原始项看作具有反应功能);并运用性能势理论,构建一种适用于平均和折扣两种性能准则的Wolf-PHC多Agent学习算法,以求解决策时刻不同步的多站点的协作Look-ahead控制策略.最后,论文通过仿真实验验证了该算法的有效性,学习结果表明,通过性能函数的改进,各工作站的负载平衡性得到改善,整个系统的工件处理率也明显提高.
文摘Generally complex 3D contours are divided into a lot of continuous small line blocks by CAD/CAM software. When these small line blocks are used in conventional way,machine tool has to stop at the end of one move before continuing on to the next to meet accuracy requirement,which results in inefficiency.Look-ahead is an intelligent function that aims at adjusting the feed rate automatically to achieve maximum productivity while maintaining accuracy.By now most researchers just utilize the simplest linear acceleration(ACC)and deceleration(DEC)to deal with look-ahead intelligence.A generalized ACC/DEC ap- proach and corresponding optimal look-ahead algorithm based on dynamic back tracking along a doubly linked list are proposed.An improved rounding strategy for reducing interpolation errors is also presented.By using the proposed techniques,arbitrary velocity profiles that offer look-ahead feature and have the desired ACC/DEC characteristics for movement of a lot of continuous line blocks can be generated efficiently.Both simulations and experiments showed the productivity was dramatically increased without sacri- fice of accuracy.
基金Special Project for Key Mechatronic Equipment of Zhejiang Province,China (No.2006Cl1067)Science & Technology Project of Zhejiang Province,China (No. 2005E10049)
文摘To avoid suffering gouge and transient overshooting in high speed cutting machining, a novel parametefized curve interpolator model with velocity look-ahead algorithm is proposed. Based on a prearrangement step interpolation algorithm for parameterized curves and considering high curvature points, parameterized curve tool path is divided into acceleration segments and deceleration segments by look-ahead algorithm. Under condition of characteristics of acceleration and deceleration stored in control system, deceleration before high curvature points and acceleration after high curvature points are realized in real-time in high speed cutting machining. Based on new parameterized curve interpolator model with velocity look-ahead algorithm, a real cubic spline is machined simulativly. The simulation results show that velocity look-ahead algorithm improves velocity changing more smoothly.
基金co-funded by the National Natural Science Foundation of China(41904109,41974146,42074134)State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development Projects(No.20-YYGZ-KF-GC-11)+2 种基金National Key Laboratory of Electromagnetic Environment Projects(No.6142403200307)Petro China Innovation Foundation(No.2020D5007-0304)the Fundamental Research Funds for the Central Universities(No.21CX06005A)。
文摘This paper presents a new deep-reading logging-while-drilling electromagnetic(EM)logging method to detect bed boundaries ahead of bit.Unlike all existing EM logging approaches,the new method is based on the scattered electric field radiated by a magnetic dipole antenna.By analyzing the characteristics of electric tensor responses in layered formations,optimal look-ahead electric component is selected.The selected scattered field contributes to a large portion of the total field and is strongly sensitive to the boundary position.The measured voltage from the scattered electric component can be tens of times larger than that from the scattered magnetic fields and it attenuates slower.Thus,the detection capability improves significantly.A coaxial open-loop half-circle antenna is then proposed to measure the electric field in logging while drilling environment.A practical tool implementation equipped with two tilted close-loop antennas and two open-loop antennas is further developed for look-ahead application.Numerical results demonstrate that the detection depth of the new look-ahead tool can be up to 40 m under favorable conditions.Compared with current look-ahead logging tools,the new method not only significantly shortens the tool size,but also can recognize the boundary position and azimuth.
文摘The principle of real-time look-ahead was introduced and analysed. An adaptive parametric curve interpolator with a real-time look-ahead function was developed for non-uniform rational B-spline (NURBS) curves interpolation, which considering the maximum acceleration/deceleration of the machine tool. In order to deal with the acceleration/deceleration around the feedrate sensitive corners, the look-ahead function was designed and illustrated. It can detect and adjust the feedrate adaptively. With the help of real-time look-ahead, the acceleration/deceleration can be limited to the range of the machine tool capacity. Thus, feedrate fluctuation is reduced. A NURBS curve interpolation experiment was provided to verify the feasibility and advantages of the proposed interpolator with a real-time look-ahead function.
基金Supported by National Natural Science Foundation of China(Grant No.92148301)
文摘When a robot is required to machine a complex curved workpiece with high precision and speed,the tool path is typically dispersed into a series of points and transmitted to the robot.The conventional trajectory planning method requires frequent starts and stops at each dispersed point to complete the task.This method not only reduces precision but also causes damage to the motors and robot.A real-time look-ahead algorithm is proposed in this paper to improve precision and minimize damage.The proposed algorithm includes a path-smoothing algorithm,a trajectory planning method,and a bidirectional scanning module.The path-smoothing method inserts a quintic Bezier curve between small adjacent line segments to achieve G^(2)continuity at the junctions.The trajectory planning method utilizes a quartic polynomial and a double-quartic polynomial that can achieve a constant velocity at the velocity limitation.The bidirectional scanning module calculates the velocity at each trajectory planning segment point,simplifying calculation complexity and can be run in real time.The feasibility of the proposed algorithm is verified through simulations and experiments,which can be run in real time.In addition,high machining precision can be achieved by adjusting the relevant parameters.
基金supported by the National Natural Science Foundation of China(Grant Nos.11572264,11172247,11402214,and 61373009)
文摘With the development of traffic systems, some issues such as traffic jams become more and more serious. Efficient traffic flow theory is needed to guide the overall controlling, organizing and management of traffic systems. On the basis of the cellular automata model and the traffic flow model with look-ahead potential, a new cellular automata traffic flow model with negative exponential weighted look-ahead potential is presented in this paper. By introducing the negative exponential weighting coefficient into the look-ahead potential and endowing the potential of vehicles closer to the driver with a greater coefficient, the modeling process is more suitable for the driver’s random decision-making process which is based on the traffic environment that the driver is facing. The fundamental diagrams for different weighting parameters are obtained by using numerical simulations which show that the negative exponential weighting coefficient has an obvious effect on high density traffic flux. The complex high density non-linear traffic behavior is also reproduced by numerical simulations.
基金supported by the National Natural Science Foundation of China(No.52077060).
文摘The increasing penetration of renewable energy resources degrades the frequency stability of power systems.The present work addresses this issue by proposing a look-ahead dispatch model of power systems based on a linear alternating current optimal power flow framework with nonlinear frequency constraints.Meanwhile,the poor efficiency for solving this formulation is addressed by introducing a physics-informed neural network(PINN)to predict key frequency-control parameter values accurately.The PINN ensures that the learned results are applicable to the original physical frequency dynamics model,and applying the predicted parameter values enables the resulting dispatch model to be solved quickly and efficiently using readily available commercial solvers.The feasibility and advantages of the proposed model are demonstrated by the results of numerical computations applied to a modified IEEE 118-bus test system.
基金supported by the National Key Basic Research Project of China (Grant Nos 2011CB302400)the National Natural Science Foundation of China (Grant Nos 60821002, 10871195, 10925105)+1 种基金Major National S&T Project "Advanced CNC Systems"CAS Project "MM Methods for Advanced CNC Systems"
文摘CNC machining plays an important role in mechanical manufacturing.A key issue is to improve the machining feedrate while keeping the machining precision and satisfying the acceleration constraints of the CNC machine.For the consecutive micro-line segments interpolation,the velocities at the junction of two segments are the bottlenecks for the machining efficiency.This paper proposes a multi-period turning method to improve the feedrate at the junctions using the linear acceleration and deceleration mode,which utilizes the maximal acceleration capabilities of the NC machine while satisfying the machining precision.A new and more efficient look-ahead method and a feedrate override method are also proposed to boast the global machining speed.The proposed algorithm has been implemented on Blue Sky NC System,and experimented in real material manufacturing.Compared with several existing algorithms,the current algorithm can improve the manufacturing time ranging from 50% to 180%,depending on the machining parameters,and also results in better machining quality.In addition,the algorithm also satisfies the need of real-time interpolation.
基金This work was supported by a Research Grant of Pukyong National University(2020).
文摘The roll-out of a flexible ramping product provides independent system operators(ISOs)with the ability to address the issues of ramping capacity shortage.ISOs procure flexible ramping capability by committing more generating units or reserving a certain amount of headrooms of committed units.In this paper,we raise the concern of the possibility that the procured flexible ramping capability cannot be deployed in realtime operations due to the unit shut-down in a look-ahead commitment(LAC)procedure.As a solution to the issues of ramping capacity shortage,we provide a modified ramping product formulation designed to improve the reliability and reduce the expected operating cost.The trajectories of start-up and shutdown processes are also considered in determining the ramping capability.A new optimization problem is formulated using mixed integer linear programming(MILP)to be readily applied to the practical power system operation.The performance of this proposed method is verified through simulations using a small-scale system and IEEE 118-bus system.The simulation results demonstrate that the proposed method can improve the generation scheduling by alleviating the ramping capacity shortages.
文摘It is intuitive that allowing a deeper search into a game tree will result in a superior player to one that is restricted in the depth of the search that it is allowed to make. Of course, searching deeper into the tree comes at increased computational cost and this is one of the trade-offs that has to be considered in developing a tree-based search algorithm. There has been some discussion as to whether the evaluation function, or the depth of the search, is the main contributory factor in the performance of an evolved checkers player. Some previous research has investigated this question （on Chess and Othello）, with differing conclusions. This suggests that different games have different emphases, with respect to these two factors. This paper provides the evidence for evolutionary checkers, and shows that the look-ahead depth （like Chess, perhaps unsurprisingly） is important. This is the first time that such an intensive study has been carried out for evolutionary checkers and given the evidence provided for Chess and Othello this is an important study that provides the evidence for another game. We arrived at our conclusion by evolving various checkers players at different ply depths and by playing them against one another, again at different ply depths. This was combined with the two-move ballot （enabling more games against the evolved players to take place） which provides strong evidence that depth of the look-ahead is important for evolved checkers players.
