There is an old saying,“Give a man a fish,and he will eat for a day.Teach a man to fish,and he will eat for the rest of his life.”In clinical teaching,students should not only be taught about diseases,but their inte...There is an old saying,“Give a man a fish,and he will eat for a day.Teach a man to fish,and he will eat for the rest of his life.”In clinical teaching,students should not only be taught about diseases,but their intelligence should also be cultivated,along with their analytical,comprehension,and independent learning skills.The ability to solve problems enables students to think independently and acquire knowledge.This is known as the heuristic method of teaching.In this study,we mainly analyze the application value of the heuristic method in the clinical teaching of internal medicine.展开更多
The evaluation of the minimum distance of linear block codes remains an open problem in coding theory, and it is not easy to determine its true value by classical methods, for this reason the problem has been solved i...The evaluation of the minimum distance of linear block codes remains an open problem in coding theory, and it is not easy to determine its true value by classical methods, for this reason the problem has been solved in the literature with heuristic techniques such as genetic algorithms and local search algorithms. In this paper we propose two approaches to attack the hardness of this problem. The first approach is based on genetic algorithms and it yield to good results comparing to another work based also on genetic algorithms. The second approach is based on a new randomized algorithm which we call 'Multiple Impulse Method (MIM)', where the principle is to search codewords locally around the all-zero codeword perturbed by a minimum level of noise, anticipating that the resultant nearest nonzero codewords will most likely contain the minimum Hamming-weight codeword whose Hamming weight is equal to the minimum distance of the linear code.展开更多
A job shop scheduling problem with a combination processing in complex production environment is proposed. Based on the defining of "non-elastic combination processing relativity" and "virtual process", the proble...A job shop scheduling problem with a combination processing in complex production environment is proposed. Based on the defining of "non-elastic combination processing relativity" and "virtual process", the problem can be simplified and transformed to a traditional one. On the basis of the dispatching rules select engine and considered factors of complex production environment, a heuristic method is designed. The algorithm has been applied to a mould enterprise in Shenzhen for half a year. The practice showed that by using the method suggested the number of delayed orders was decreased about 20% and the productivity was increased by 10 to 20%.展开更多
The traditional approach to solvent selction in the extractive distillation process strictly focuses on the change in the relative voltility of light-heavy components induced by the solvent.However,the total annual co...The traditional approach to solvent selction in the extractive distillation process strictly focuses on the change in the relative voltility of light-heavy components induced by the solvent.However,the total annual cost of the process may not be minimal when the solvent induces the largest change in relative volatility.This work presents a heuristic method for selecting the optimal solvent to minimize the total annual cost.The functional relationship between the relative volatility and the total annual cost is established,where the main factors,such as the relative volatility of the light-heavy components and the relative volatility of the heavy-component solvent,are taken into account.Binary azeotropic mixtures of methanol-toluene and methanol-acetone are separated to verify the feasibility of the model.The results show that using the solvent with the minimal two-column extractive distillation index,the process achieves a minimal total annual cost.The method is conducive for sustainable advancements in chemistry and engineering because a suitable solvent can be selected without simulation verification.展开更多
The vehicle routing problem(VRP) is a well-known combinatorial optimization issue in transportation and logistics network systems. There exist several limitations associated with the traditional VRP. Releasing the res...The vehicle routing problem(VRP) is a well-known combinatorial optimization issue in transportation and logistics network systems. There exist several limitations associated with the traditional VRP. Releasing the restricted conditions of traditional VRP has become a research focus in the past few decades. The vehicle routing problem with split deliveries and pickups(VRPSPDP) is particularly proposed to release the constraints on the visiting times per customer and vehicle capacity, that is, to allow the deliveries and pickups for each customer to be simultaneously split more than once. Few studies have focused on the VRPSPDP problem. In this paper we propose a two-stage heuristic method integrating the initial heuristic algorithm and hybrid heuristic algorithm to study the VRPSPDP problem. To validate the proposed algorithm, Solomon benchmark datasets and extended Solomon benchmark datasets were modified to compare with three other popular algorithms. A total of 18 datasets were used to evaluate the effectiveness of the proposed method. The computational results indicated that the proposed algorithm is superior to these three algorithms for VRPSPDP in terms of total travel cost and average loading rate.展开更多
In the paper we discuss and compare two commonly used methods of finding the shortest paths in networks,namely Dijkstra’s and A*algorithms.We compare their effectiveness in terms of traversing road network in circums...In the paper we discuss and compare two commonly used methods of finding the shortest paths in networks,namely Dijkstra’s and A*algorithms.We compare their effectiveness in terms of traversing road network in circumstances that require swift decision making in the event of dynamically changing road conditions on the basis of studies conducted for evacuation plans.To build a proper model of such a network,a method of appropriate edge-weighting is introduced,based on empirical data collected by other researchers.Then,we use the basics of the theory of quasimetric spaces to introduce a heuristic to such graphs,which is easy to calculate metric.The heuristic we obtain is both admissible and consistent,which allows us to use it efficiently in A*search algorithms.The developed application can be used in studies into evacuation from hazardous areas.In this case,optimum calculative efficiency is achievable with a simultaneous reduction of calculation time(when compared to Dijkstra’s algorithm).Our application can be applied during the first stage,i.e.,prior to the occurrence of a disaster,since this is an appropriate time for preparation by planning,drilling,early warning,and designating the rescue services that are to participate in the following stages.展开更多
Assume there are several states, and the objective function f\+s(x) is linked with each state s. Robust optimization is to solve the following problem: min x∈X max s∈Sf\+s(x)where X is the feasible s...Assume there are several states, and the objective function f\+s(x) is linked with each state s. Robust optimization is to solve the following problem: min x∈X max s∈Sf\+s(x)where X is the feasible solution set, and S is the collection of states.\;It has been showed that most of robust combinatorial optimization problems are NP\|hard in strong sense. In this paper, we will discuss the borderline between the ′easy′ and the ′hard′ cases of robust combinatorial optimization problems, and further present a heuristic frame work to solve the ′hard′ problems and discuss their concrete implementation of the heuristic method.展开更多
Purpose–The purpose of this paper is to develop a real-time trajectory planner with optimal maneuver for autonomous vehicles to deal with dynamic obstacles during parallel parking.Design/methodology/approach–To deal...Purpose–The purpose of this paper is to develop a real-time trajectory planner with optimal maneuver for autonomous vehicles to deal with dynamic obstacles during parallel parking.Design/methodology/approach–To deal with dynamic obstacles for autonomous vehicles during parking,a long-and short-term mixed trajectory planning algorithm is proposed in this paper.In long term,considering obstacle behavior,A-star algorithm was improved by RS curve and potential function via spatio-temporal map to obtain a safe and efficient initial trajectory.In short term,this paper proposes a nonlinear model predictive control trajectory optimizer to smooth and adjust the trajectory online based on the vehicle kinematic model.Moreover,the proposed method is simulated and verified in four common dynamic parking scenarios by ACADO Toolkit and QPOASE solver.Findings–Compared with the spline optimization method,the results show that the proposed method can generate efficient obstacle avoidance strategies,safe parking trajectories and control parameters such as the front wheel angle and velocity in high-efficient central processing units.Originality/value–It is aimed at improving the robustness of automatic parking system and providing a reference for decision-making in a dynamic environment.展开更多
This study examines the multicriteria scheduling problem on a single machine to minimize three criteria: the maximum cost function, denoted by maximum late work (V<sub>max</sub>), maximum tardy job, denote...This study examines the multicriteria scheduling problem on a single machine to minimize three criteria: the maximum cost function, denoted by maximum late work (V<sub>max</sub>), maximum tardy job, denoted by (T<sub>max</sub>), and maximum earliness (E<sub>max</sub>). We propose several algorithms based on types of objectives function to be optimized when dealing with simultaneous minimization problems with and without weight and hierarchical minimization problems. The proposed Algorithm (3) is to find the set of efficient solutions for 1//F (V<sub>max</sub>, T<sub>max</sub>, E<sub>max</sub>) and 1//(V<sub>max</sub> + T<sub>max</sub> + E<sub>max</sub>). The Local Search Heuristic Methods (Descent Method (DM), Simulated Annealing (SA), Genetic Algorithm (GA), and the Tree Type Heuristics Method (TTHM) are applied to solve all suggested problems. Finally, the experimental results of Algorithm (3) are compared with the results of the Branch and Bound (BAB) method for optimal and Pareto optimal solutions for smaller instance sizes and compared to the Local Search Heuristic Methods for large instance sizes. These results ensure the efficiency of Algorithm (3) in a reasonable time.展开更多
In this work,forward current voltage characteristics for multi-quantum wells Al_(0.33)Ga_(0.67)As Schottky diode were measured at temperature ranges from 100 to 300 K.The main parameters of this Schottky diode,such as...In this work,forward current voltage characteristics for multi-quantum wells Al_(0.33)Ga_(0.67)As Schottky diode were measured at temperature ranges from 100 to 300 K.The main parameters of this Schottky diode,such as the ideality factor,barrier height,series resistance and saturation current,have been extracted using both analytical and heuristics methods.Differential evolution(DE),particle swarm optimization(PSO)and artificial bee colony(ABC)have been chosen as candidate heuristics algorithms,while Cheung technic was selected as analytical extraction method.The obtained results show clearly the high performance of DE algorithms in terms of parameters accuracy,convergence speed and robustness.展开更多
This paper studies the solution technique to solve the DRAMA spares allocation optimization problem. DRAMA model is an analytic spare optimization model of a multi-item, multi-location, and two-echelon inventory syste...This paper studies the solution technique to solve the DRAMA spares allocation optimization problem. DRAMA model is an analytic spare optimization model of a multi-item, multi-location, and two-echelon inventory system. The computation of its system spares availability is much complicated. The objective function and constraint functions of DRAMA model could be written as the separable forms. A new bound heuristic algorithm has been presented by improving the bound heuristic algorithm for solving the reliability redundancy optimization problem (BHA in short). With the results, the proposed algorithm has been found to be more economical and effective than BHA to obtain the solutions of large DRAMA model. The new algorithm could be used to solve reliability redundancy optimization problems with the separable forms.展开更多
Turkey is highly prone to landslides because of the geological and geographic location.The study area,which is located in a tectonically active region,has been significantly affected by mass movements.Flow type landsl...Turkey is highly prone to landslides because of the geological and geographic location.The study area,which is located in a tectonically active region,has been significantly affected by mass movements.Flow type landslides are frequently observed due to this location.This study aims at determining the source area and propagation of debris flows in the study area.We used the heuristic method to extract source areas of debris flow,and then used receiver operating characteristic(ROC)curve analysis to assess the performance of the method,and finally calculated the Area under curve(AUC)values being 83.64%and 80.39%for the success rate and prediction rate,respectively.We calculated potential propagation area and runout distance with Flow-R software.In conclusion,the obtained results(susceptibility map,propagation and runout distance)are very important for decisionmakers at the region located on an active fault zone,which is highly prone to natural disasters.The outputs of this study could be used in site selection studies,designing erosion prevention systems and protecting existing human-made structures.展开更多
Airlines adjust their flight schedules to satisfy more stringent airport capacity constraints caused by inclement weather or other unexpected disruptions.The problem will be more important and complicated if uncertain...Airlines adjust their flight schedules to satisfy more stringent airport capacity constraints caused by inclement weather or other unexpected disruptions.The problem will be more important and complicated if uncertain disruptions occur in hub airports.A two-stage stochastic programming model was established to deal with the realtime flight schedule recovery and passenger re-accommodation problem.The first-stage model represents the flight re-timing and re-fleeting decision in current time period when capacity information is deterministic,while the second-stage recourse model evaluates the passenger delay given the first-stage solutions when one future scenario is realized.Aiming at the large size of the problem and requirement for quick response,an algorithmic framework combining the sample average approximation and heuristic method was proposed.The computational results indicated of that the proposed method could obtain solutions with around 5% optimal gaps,and the computing time was linearly positive to the sample size.展开更多
This paper addresses the scheduling and inventory management of a straight pipeline system connecting a single refinery to multiple distribution centers.By increasing the number of batches and time periods,maintaining...This paper addresses the scheduling and inventory management of a straight pipeline system connecting a single refinery to multiple distribution centers.By increasing the number of batches and time periods,maintaining the model resolution by using linear programming-based methods and commercial solvers would be very time-consuming.In this paper,we make an attempt to utilize the problem structure and develop a decomposition-based algorithm capable of finding near-optimal solutions for large instances in a reasonable time.The algorithm starts with a relaxed version of the model and adds a family of cuts on the fly,so that a near-optimal solution is obtained within a few iterations.The idea behind the cut generation is based on the knowledge of the underlying problem structure.Computational experiments on a real-world data case and some randomly generated instances confirm the efficiency of the proposed algorithm in terms of the solution quality and time.展开更多
A quantitative structure-retention relationship(QSRR) study has been carried out on the gas chromatograph-mass spectrometry(GC-MS) system retention time(RT) of two sets of illicit drugs by using molecular struct...A quantitative structure-retention relationship(QSRR) study has been carried out on the gas chromatograph-mass spectrometry(GC-MS) system retention time(RT) of two sets of illicit drugs by using molecular structural descriptors.Heuristic method(HM) was utilized to construct the linear models.Appropriate models with low standard errors and high correlation coefficients were obtained(R2=0.9873,F=390.18 for data set 1 and R2=0.9881,F=749.13 for data set 2).The results of leave-one-out cross validation showed good predictive ability of these proposed models(R c2v= 0.9812 and R c2v= 0.9824,respectively).Each molecular descriptor in the two models was disputed to unfold the relationship between the molecular structures and RT.展开更多
Digital twin is regarded as the next-generation technology for the effective operation of heating,ventilation and air conditioning(HVAC)systems.It is essential to calibrate the digital twin models to match them closel...Digital twin is regarded as the next-generation technology for the effective operation of heating,ventilation and air conditioning(HVAC)systems.It is essential to calibrate the digital twin models to match them closely with real physical systems.Conventional real-time calibration methods cannot satisfy such requirements since the computation loads are beyond acceptable tolerances.To address this challenge,this study proposes a clustering compression-based method to enhance the computation efficiency of digital twin model calibration for HVAC systems.This method utilizes clustering algorithms to remove redundant data for achieving data compression.Moreover,a hierarchical multi-stage heuristic model calibration strategy is developed to accelerate the calibration of similar component models.Its basic idea is that once a component model is calibrated by heuristic methods,its optimal solution is utilized to narrow the ranges of parameter probability distributions of similar components.By doing so,the calibration process can be guided,so that fewer iterations would be used.The performance of the proposed method is evaluated using the operational data from an HVAC system in an industrial building.Results show that the proposed clustering compression-based method can reduce computation loads by 97%,compared to the conventional calibration method.And the proposed hierarchical heuristic model calibration strategy is capable of accelerating the calibration process after clustering and saves 14.6%of the time costs.展开更多
In cabin-type component alignment, digital measurement technology is usually adopted to provide guidance for assembly. Depending on the system of measurement, the alignment process can be divided into measurement-assi...In cabin-type component alignment, digital measurement technology is usually adopted to provide guidance for assembly. Depending on the system of measurement, the alignment process can be divided into measurement-assisted assembly(MAA) and force-driven assembly. In MAA,relative pose between components is directly measured to guide assembly, while in force-driven assembly, only contact state can be recognized according to measured six-dimensional force and torque(6 D F/T) and the process is completed based on preset assembly strategy. Aiming to improve the efficiency of force-driven cabin-type component alignment, this paper proposed a heuristic alignment method based on multi-source data fusion. In this method, measured 6 D F/T, pose data and geometric information of components are fused to calculate the relative pose between components and guide the movement of pose adjustment platform. Among these data types, pose data and measured 6 D F/T are combined as data set. To collect the data sets needed for data fusion, dynamic gravity compensation method and hybrid motion control method are designed. Then the relative pose calculation method is elaborated, which transforms collected data sets into discrete geometric elements and calculates the relative poses based on the geometric information of components.Finally, experiments are conducted in simulation environment and the results show that the proposed alignment method is feasible and effective.展开更多
The present study was an attempt to delineate potential groundwater zones in Kalikavu Panchayat of Malappuram district,Kerala,India.The geo-spatial database on geomorphology,landuse,geology,slope and drainage network ...The present study was an attempt to delineate potential groundwater zones in Kalikavu Panchayat of Malappuram district,Kerala,India.The geo-spatial database on geomorphology,landuse,geology,slope and drainage network was generated in a geographic information system(GIS)environment from satellite data,Survey of India topographic sheets and field observations.To understand the movement and occurrence of groundwater,the geology,geomorphology,structural set-up and recharging conditions have to be well understood.In the present study,the potential recharge areas are delineated in terms of geology,geomorphology,land use,slope,drainage pattern,etc.Various thematic data generated were integrated using a heuristic method in the GIS domain to generate maps showing potential groundwater zones.The composite output map scores were reclassified into different zones using a decision rule.The final output map shows different zones of groundwater prospect,viz.,very good(15.57%of the area),good(43.74%),moderate(28.38%)and poor(12.31%).Geomorphic units such as valley plains,valley fills and alluvial terraces were identified as good to excellent prospect zones,while the gently sloping lateritic uplands were identified as good to moderate zones.Steeply sloping hilly terrains underlain by hard rocks were identified as poor groundwater prospect zones.展开更多
The analysis of the finite difference schemes with nonuniform meshes for the problems of partial differential equations is extremely rare even for very simple problems and even for the method of fully heuristic charac...The analysis of the finite difference schemes with nonuniform meshes for the problems of partial differential equations is extremely rare even for very simple problems and even for the method of fully heuristic character. In the present work the boundary value problem for quasilinear parabolic system is solved by the finite difference method with nonuniform meshes. By using of the interpolation formulas for the spaces of discrete functions with unequal meshsteps and the method of a priori estimation for the discrete solutions of finite difference schemes with nonuniform meshes, the absolute and relative convergence of the discrete solutions of the finite defference scheme are proved. The limiting vector function is just the unique generalized solution of the original problem for the parabolic system.展开更多
This paper uses a novel scenario generation method for tackling the uncertainties of wind power in the transmission network expansion planning(TNEP)problem.A heuristic moment matching(HMM)method is first applied to ge...This paper uses a novel scenario generation method for tackling the uncertainties of wind power in the transmission network expansion planning(TNEP)problem.A heuristic moment matching(HMM)method is first applied to generate the typical scenarios for capturing the stochastic features of wind power,including expectation,standard deviation,skewness,kurtosis,and correlation of multiple wind farms.Then,based on the typical scenarios,a robust TNEP problem is presented and formulated.The solution of the problem is robust against all the scenarios that represent the stochastic features of wind power.Three test systems are used to verify the HMM method and is compared against Taguchi’s Orthogonal Array(OA)method.The simulation results show that the HMM method has better performance than the OA method in terms of the trade-off between robustness and economy.Additionally,the main factors influencing the planning scheme are studied,including the number of scenarios,wind farm capacity,and penalty factors,which provide a reference for system operators choosing parameters.展开更多
文摘There is an old saying,“Give a man a fish,and he will eat for a day.Teach a man to fish,and he will eat for the rest of his life.”In clinical teaching,students should not only be taught about diseases,but their intelligence should also be cultivated,along with their analytical,comprehension,and independent learning skills.The ability to solve problems enables students to think independently and acquire knowledge.This is known as the heuristic method of teaching.In this study,we mainly analyze the application value of the heuristic method in the clinical teaching of internal medicine.
文摘The evaluation of the minimum distance of linear block codes remains an open problem in coding theory, and it is not easy to determine its true value by classical methods, for this reason the problem has been solved in the literature with heuristic techniques such as genetic algorithms and local search algorithms. In this paper we propose two approaches to attack the hardness of this problem. The first approach is based on genetic algorithms and it yield to good results comparing to another work based also on genetic algorithms. The second approach is based on a new randomized algorithm which we call 'Multiple Impulse Method (MIM)', where the principle is to search codewords locally around the all-zero codeword perturbed by a minimum level of noise, anticipating that the resultant nearest nonzero codewords will most likely contain the minimum Hamming-weight codeword whose Hamming weight is equal to the minimum distance of the linear code.
基金Supported by Research Fund for the Doctoral Program of Higher Education of China(20060487072)National Key Technology R&D Program(2006BAF01A43)
文摘A job shop scheduling problem with a combination processing in complex production environment is proposed. Based on the defining of "non-elastic combination processing relativity" and "virtual process", the problem can be simplified and transformed to a traditional one. On the basis of the dispatching rules select engine and considered factors of complex production environment, a heuristic method is designed. The algorithm has been applied to a mould enterprise in Shenzhen for half a year. The practice showed that by using the method suggested the number of delayed orders was decreased about 20% and the productivity was increased by 10 to 20%.
基金This work is supported by the National Natural Science Foundation of China(Grant Nos.21776145 and 21676152).
文摘The traditional approach to solvent selction in the extractive distillation process strictly focuses on the change in the relative voltility of light-heavy components induced by the solvent.However,the total annual cost of the process may not be minimal when the solvent induces the largest change in relative volatility.This work presents a heuristic method for selecting the optimal solvent to minimize the total annual cost.The functional relationship between the relative volatility and the total annual cost is established,where the main factors,such as the relative volatility of the light-heavy components and the relative volatility of the heavy-component solvent,are taken into account.Binary azeotropic mixtures of methanol-toluene and methanol-acetone are separated to verify the feasibility of the model.The results show that using the solvent with the minimal two-column extractive distillation index,the process achieves a minimal total annual cost.The method is conducive for sustainable advancements in chemistry and engineering because a suitable solvent can be selected without simulation verification.
基金Project supported by the National Natural Science Foundation of China(No.51138003)the National Social Science Foundation of Chongqing of China(No.2013YBJJ035)
文摘The vehicle routing problem(VRP) is a well-known combinatorial optimization issue in transportation and logistics network systems. There exist several limitations associated with the traditional VRP. Releasing the restricted conditions of traditional VRP has become a research focus in the past few decades. The vehicle routing problem with split deliveries and pickups(VRPSPDP) is particularly proposed to release the constraints on the visiting times per customer and vehicle capacity, that is, to allow the deliveries and pickups for each customer to be simultaneously split more than once. Few studies have focused on the VRPSPDP problem. In this paper we propose a two-stage heuristic method integrating the initial heuristic algorithm and hybrid heuristic algorithm to study the VRPSPDP problem. To validate the proposed algorithm, Solomon benchmark datasets and extended Solomon benchmark datasets were modified to compare with three other popular algorithms. A total of 18 datasets were used to evaluate the effectiveness of the proposed method. The computational results indicated that the proposed algorithm is superior to these three algorithms for VRPSPDP in terms of total travel cost and average loading rate.
基金the National Science Centre in Poland,grant number 2018/29/B/HS4/01020o-funded under the framework of the subsidy for tertiary education,aimed at academies and universities which participated in the IDUB Contest(“Inicjatywa Doskona?o sci-Uczelnia Badawcza”)。
文摘In the paper we discuss and compare two commonly used methods of finding the shortest paths in networks,namely Dijkstra’s and A*algorithms.We compare their effectiveness in terms of traversing road network in circumstances that require swift decision making in the event of dynamically changing road conditions on the basis of studies conducted for evacuation plans.To build a proper model of such a network,a method of appropriate edge-weighting is introduced,based on empirical data collected by other researchers.Then,we use the basics of the theory of quasimetric spaces to introduce a heuristic to such graphs,which is easy to calculate metric.The heuristic we obtain is both admissible and consistent,which allows us to use it efficiently in A*search algorithms.The developed application can be used in studies into evacuation from hazardous areas.In this case,optimum calculative efficiency is achievable with a simultaneous reduction of calculation time(when compared to Dijkstra’s algorithm).Our application can be applied during the first stage,i.e.,prior to the occurrence of a disaster,since this is an appropriate time for preparation by planning,drilling,early warning,and designating the rescue services that are to participate in the following stages.
基金Research is supported by the National 863 Program ( No.863- 306- Z T
文摘Assume there are several states, and the objective function f\+s(x) is linked with each state s. Robust optimization is to solve the following problem: min x∈X max s∈Sf\+s(x)where X is the feasible solution set, and S is the collection of states.\;It has been showed that most of robust combinatorial optimization problems are NP\|hard in strong sense. In this paper, we will discuss the borderline between the ′easy′ and the ′hard′ cases of robust combinatorial optimization problems, and further present a heuristic frame work to solve the ′hard′ problems and discuss their concrete implementation of the heuristic method.
基金the National Natural Science Foundation of China(Nos.51875184 and 52002163).
文摘Purpose–The purpose of this paper is to develop a real-time trajectory planner with optimal maneuver for autonomous vehicles to deal with dynamic obstacles during parallel parking.Design/methodology/approach–To deal with dynamic obstacles for autonomous vehicles during parking,a long-and short-term mixed trajectory planning algorithm is proposed in this paper.In long term,considering obstacle behavior,A-star algorithm was improved by RS curve and potential function via spatio-temporal map to obtain a safe and efficient initial trajectory.In short term,this paper proposes a nonlinear model predictive control trajectory optimizer to smooth and adjust the trajectory online based on the vehicle kinematic model.Moreover,the proposed method is simulated and verified in four common dynamic parking scenarios by ACADO Toolkit and QPOASE solver.Findings–Compared with the spline optimization method,the results show that the proposed method can generate efficient obstacle avoidance strategies,safe parking trajectories and control parameters such as the front wheel angle and velocity in high-efficient central processing units.Originality/value–It is aimed at improving the robustness of automatic parking system and providing a reference for decision-making in a dynamic environment.
文摘This study examines the multicriteria scheduling problem on a single machine to minimize three criteria: the maximum cost function, denoted by maximum late work (V<sub>max</sub>), maximum tardy job, denoted by (T<sub>max</sub>), and maximum earliness (E<sub>max</sub>). We propose several algorithms based on types of objectives function to be optimized when dealing with simultaneous minimization problems with and without weight and hierarchical minimization problems. The proposed Algorithm (3) is to find the set of efficient solutions for 1//F (V<sub>max</sub>, T<sub>max</sub>, E<sub>max</sub>) and 1//(V<sub>max</sub> + T<sub>max</sub> + E<sub>max</sub>). The Local Search Heuristic Methods (Descent Method (DM), Simulated Annealing (SA), Genetic Algorithm (GA), and the Tree Type Heuristics Method (TTHM) are applied to solve all suggested problems. Finally, the experimental results of Algorithm (3) are compared with the results of the Branch and Bound (BAB) method for optimal and Pareto optimal solutions for smaller instance sizes and compared to the Local Search Heuristic Methods for large instance sizes. These results ensure the efficiency of Algorithm (3) in a reasonable time.
文摘In this work,forward current voltage characteristics for multi-quantum wells Al_(0.33)Ga_(0.67)As Schottky diode were measured at temperature ranges from 100 to 300 K.The main parameters of this Schottky diode,such as the ideality factor,barrier height,series resistance and saturation current,have been extracted using both analytical and heuristics methods.Differential evolution(DE),particle swarm optimization(PSO)and artificial bee colony(ABC)have been chosen as candidate heuristics algorithms,while Cheung technic was selected as analytical extraction method.The obtained results show clearly the high performance of DE algorithms in terms of parameters accuracy,convergence speed and robustness.
文摘This paper studies the solution technique to solve the DRAMA spares allocation optimization problem. DRAMA model is an analytic spare optimization model of a multi-item, multi-location, and two-echelon inventory system. The computation of its system spares availability is much complicated. The objective function and constraint functions of DRAMA model could be written as the separable forms. A new bound heuristic algorithm has been presented by improving the bound heuristic algorithm for solving the reliability redundancy optimization problem (BHA in short). With the results, the proposed algorithm has been found to be more economical and effective than BHA to obtain the solutions of large DRAMA model. The new algorithm could be used to solve reliability redundancy optimization problems with the separable forms.
文摘Turkey is highly prone to landslides because of the geological and geographic location.The study area,which is located in a tectonically active region,has been significantly affected by mass movements.Flow type landslides are frequently observed due to this location.This study aims at determining the source area and propagation of debris flows in the study area.We used the heuristic method to extract source areas of debris flow,and then used receiver operating characteristic(ROC)curve analysis to assess the performance of the method,and finally calculated the Area under curve(AUC)values being 83.64%and 80.39%for the success rate and prediction rate,respectively.We calculated potential propagation area and runout distance with Flow-R software.In conclusion,the obtained results(susceptibility map,propagation and runout distance)are very important for decisionmakers at the region located on an active fault zone,which is highly prone to natural disasters.The outputs of this study could be used in site selection studies,designing erosion prevention systems and protecting existing human-made structures.
基金supported by the National Natural Science Foundation of China(Nos.61079014,71171111)the Funding of Outstanding Doctoral Dissertation in Nanjing University of Aeronautics and Astronautics(No.BCXJ1314)the Funding of Jiangsu Innovation Program for Graduate Education(No.CXZZ13_0174)
文摘Airlines adjust their flight schedules to satisfy more stringent airport capacity constraints caused by inclement weather or other unexpected disruptions.The problem will be more important and complicated if uncertain disruptions occur in hub airports.A two-stage stochastic programming model was established to deal with the realtime flight schedule recovery and passenger re-accommodation problem.The first-stage model represents the flight re-timing and re-fleeting decision in current time period when capacity information is deterministic,while the second-stage recourse model evaluates the passenger delay given the first-stage solutions when one future scenario is realized.Aiming at the large size of the problem and requirement for quick response,an algorithmic framework combining the sample average approximation and heuristic method was proposed.The computational results indicated of that the proposed method could obtain solutions with around 5% optimal gaps,and the computing time was linearly positive to the sample size.
文摘This paper addresses the scheduling and inventory management of a straight pipeline system connecting a single refinery to multiple distribution centers.By increasing the number of batches and time periods,maintaining the model resolution by using linear programming-based methods and commercial solvers would be very time-consuming.In this paper,we make an attempt to utilize the problem structure and develop a decomposition-based algorithm capable of finding near-optimal solutions for large instances in a reasonable time.The algorithm starts with a relaxed version of the model and adds a family of cuts on the fly,so that a near-optimal solution is obtained within a few iterations.The idea behind the cut generation is based on the knowledge of the underlying problem structure.Computational experiments on a real-world data case and some randomly generated instances confirm the efficiency of the proposed algorithm in terms of the solution quality and time.
基金supported by the key program of National Natural Science Foundation of China (No. 90612016)
文摘A quantitative structure-retention relationship(QSRR) study has been carried out on the gas chromatograph-mass spectrometry(GC-MS) system retention time(RT) of two sets of illicit drugs by using molecular structural descriptors.Heuristic method(HM) was utilized to construct the linear models.Appropriate models with low standard errors and high correlation coefficients were obtained(R2=0.9873,F=390.18 for data set 1 and R2=0.9881,F=749.13 for data set 2).The results of leave-one-out cross validation showed good predictive ability of these proposed models(R c2v= 0.9812 and R c2v= 0.9824,respectively).Each molecular descriptor in the two models was disputed to unfold the relationship between the molecular structures and RT.
基金support of the National Natural Science Foundation of China (No.51978601 and No.52161135202).
文摘Digital twin is regarded as the next-generation technology for the effective operation of heating,ventilation and air conditioning(HVAC)systems.It is essential to calibrate the digital twin models to match them closely with real physical systems.Conventional real-time calibration methods cannot satisfy such requirements since the computation loads are beyond acceptable tolerances.To address this challenge,this study proposes a clustering compression-based method to enhance the computation efficiency of digital twin model calibration for HVAC systems.This method utilizes clustering algorithms to remove redundant data for achieving data compression.Moreover,a hierarchical multi-stage heuristic model calibration strategy is developed to accelerate the calibration of similar component models.Its basic idea is that once a component model is calibrated by heuristic methods,its optimal solution is utilized to narrow the ranges of parameter probability distributions of similar components.By doing so,the calibration process can be guided,so that fewer iterations would be used.The performance of the proposed method is evaluated using the operational data from an HVAC system in an industrial building.Results show that the proposed clustering compression-based method can reduce computation loads by 97%,compared to the conventional calibration method.And the proposed hierarchical heuristic model calibration strategy is capable of accelerating the calibration process after clustering and saves 14.6%of the time costs.
基金co-supported by the Special Research on Civil Aircraft of China (No.MJZ-2017-J-96)the Defense Industrial Technology Development Program of China (No.JCKY2016206B009)。
文摘In cabin-type component alignment, digital measurement technology is usually adopted to provide guidance for assembly. Depending on the system of measurement, the alignment process can be divided into measurement-assisted assembly(MAA) and force-driven assembly. In MAA,relative pose between components is directly measured to guide assembly, while in force-driven assembly, only contact state can be recognized according to measured six-dimensional force and torque(6 D F/T) and the process is completed based on preset assembly strategy. Aiming to improve the efficiency of force-driven cabin-type component alignment, this paper proposed a heuristic alignment method based on multi-source data fusion. In this method, measured 6 D F/T, pose data and geometric information of components are fused to calculate the relative pose between components and guide the movement of pose adjustment platform. Among these data types, pose data and measured 6 D F/T are combined as data set. To collect the data sets needed for data fusion, dynamic gravity compensation method and hybrid motion control method are designed. Then the relative pose calculation method is elaborated, which transforms collected data sets into discrete geometric elements and calculates the relative poses based on the geometric information of components.Finally, experiments are conducted in simulation environment and the results show that the proposed alignment method is feasible and effective.
文摘The present study was an attempt to delineate potential groundwater zones in Kalikavu Panchayat of Malappuram district,Kerala,India.The geo-spatial database on geomorphology,landuse,geology,slope and drainage network was generated in a geographic information system(GIS)environment from satellite data,Survey of India topographic sheets and field observations.To understand the movement and occurrence of groundwater,the geology,geomorphology,structural set-up and recharging conditions have to be well understood.In the present study,the potential recharge areas are delineated in terms of geology,geomorphology,land use,slope,drainage pattern,etc.Various thematic data generated were integrated using a heuristic method in the GIS domain to generate maps showing potential groundwater zones.The composite output map scores were reclassified into different zones using a decision rule.The final output map shows different zones of groundwater prospect,viz.,very good(15.57%of the area),good(43.74%),moderate(28.38%)and poor(12.31%).Geomorphic units such as valley plains,valley fills and alluvial terraces were identified as good to excellent prospect zones,while the gently sloping lateritic uplands were identified as good to moderate zones.Steeply sloping hilly terrains underlain by hard rocks were identified as poor groundwater prospect zones.
文摘The analysis of the finite difference schemes with nonuniform meshes for the problems of partial differential equations is extremely rare even for very simple problems and even for the method of fully heuristic character. In the present work the boundary value problem for quasilinear parabolic system is solved by the finite difference method with nonuniform meshes. By using of the interpolation formulas for the spaces of discrete functions with unequal meshsteps and the method of a priori estimation for the discrete solutions of finite difference schemes with nonuniform meshes, the absolute and relative convergence of the discrete solutions of the finite defference scheme are proved. The limiting vector function is just the unique generalized solution of the original problem for the parabolic system.
基金supported in part by the National Natural Science Foundation of China under Grant No.51377027The National Basic Research Program of China under Grant No.2013CB228205by Innovation Project of Guangxi Graduate Education under Grant No.YCSZ2015053.
文摘This paper uses a novel scenario generation method for tackling the uncertainties of wind power in the transmission network expansion planning(TNEP)problem.A heuristic moment matching(HMM)method is first applied to generate the typical scenarios for capturing the stochastic features of wind power,including expectation,standard deviation,skewness,kurtosis,and correlation of multiple wind farms.Then,based on the typical scenarios,a robust TNEP problem is presented and formulated.The solution of the problem is robust against all the scenarios that represent the stochastic features of wind power.Three test systems are used to verify the HMM method and is compared against Taguchi’s Orthogonal Array(OA)method.The simulation results show that the HMM method has better performance than the OA method in terms of the trade-off between robustness and economy.Additionally,the main factors influencing the planning scheme are studied,including the number of scenarios,wind farm capacity,and penalty factors,which provide a reference for system operators choosing parameters.