Due to the current trend towards lightweight design in automotive industry,hollow stepped gear shafts for automobile and its radial forging process are widely investigated.Utilizing coupled finite element thermo-mecha...Due to the current trend towards lightweight design in automotive industry,hollow stepped gear shafts for automobile and its radial forging process are widely investigated.Utilizing coupled finite element thermo-mechanical model,radial forging process of a hollow stepped gear shaft for automobile was simulated.The optimal combination of three process parameters including initial temperature,rotation rate and radial reduction was also selected using orthogonal design method.To examine the strain inhomogeneity of the forging workpiece,the strain inhomogeneity factor was introduced.The results reveal that the maximum effective strain and the minimum effective strain appeared in the outermost and innermost zones of different cross sections for the hollow stepped gear shaft,respectively.Optimal forging parameters are determined as a combination of initial temperature of 780°C,rotation rate of 21°/stroke and radial reduction of 3 mm.展开更多
Orthogonal waveform design is quite an important issue for waveform diversity systems. A chaos based method for the orthogonal discrete frequency coding waveform （DFCW） design is proposed to increase the insufficien...Orthogonal waveform design is quite an important issue for waveform diversity systems. A chaos based method for the orthogonal discrete frequency coding waveform （DFCW） design is proposed to increase the insufficient orthogonal waveform number and their finite coding length. Premises for chaos choosing and the frequency quantification method are discussed to obtain the best correlation properties. Simulation results show the validity of the theoretic analysis.展开更多
Room and pillar sizes are key factors for safe mining and ore recovery in open-stope mining. To investigate the influence of room and pillar configurations on stope stability in highly fractured and weakened areas, an...Room and pillar sizes are key factors for safe mining and ore recovery in open-stope mining. To investigate the influence of room and pillar configurations on stope stability in highly fractured and weakened areas, an orthogonal design with two factors, three levels and nine runs was proposed, followed by three-dimensional numerical simulation using ANSYS and FLAC3~. Results show that surface settlement after excavation is concentrically ringed, and increases with the decrease of pillar width and distances to stope gobs. In the meantime, the ore-control fault at the ore-rock boundary and the fractured argillaceous dolomite with intercalated slate at the hanging wall deteriorate the roof settlement. Additionally, stope stability is challenged due to pillar rheological yield and stress concentration, and both are induced by redistribution of stress and plastic zones after mining. Following an objective function and a constraint function, room and pillar configuration with widths of 14 m and 16 m, respectively, is presented as the optimization for improving the ore recovery rate while maintaining a safe working environment.展开更多
Wind barriers have attracted significant attention as an effective measure to ensure train safety under crosswinds.However,in past decades,the influence of structural parameters such as the height and ventilation rati...Wind barriers have attracted significant attention as an effective measure to ensure train safety under crosswinds.However,in past decades,the influence of structural parameters such as the height and ventilation ratio of wind barriers on the difference of the average pressure coefficient between the train windward and leeward surface(ΔCp)has not been fully investigated.To determine the influence of the interaction among the three factors,namely the wind barrier height(H),ventilation ratio(R),and distance to the train(D),twenty five numerical simulation cases with different structural parameters were considered based on an orthogonal design.The shear stress transfer(SST)k-ωturbulent model was employed to calculate the wind pressure coefficients,and the calculation accuracy was validated by using wind tunnel experiments.The results indicated that with an increase in R,ΔCp first decreased and then increased,andΔCp decreased while D increased.Moreover,with the increase in H,ΔCp first increased and then decreased.Therefore,these three factors must be considered during the installation of wind barriers.Furthermore,according to a range analysis(judging the relative importance of the three factors intuitively),the three factors were ranked in the following order:R>H>D.Based on a variance analysis,R was found to be of high significance toΔCp,followed by H,which was significant,whereas D had relatively insignificant influence.Finally,the optimal values of R and H were determined to be 20%and 110 mm,respectively.And when R=40%,H=85 mm,the train was relatively unsafe under these such conditions.The findings of this study provide significant guidance for the structural design of wind barriers.展开更多
A new multi-species particle swarm optimization with a two-level hierarchical topology and the orthogonal learning strategy(OMSPSO) is proposed, which enhances the global search ability of particles and increases thei...A new multi-species particle swarm optimization with a two-level hierarchical topology and the orthogonal learning strategy(OMSPSO) is proposed, which enhances the global search ability of particles and increases their convergence rates. The numerical results on 10 benchmark functions demonstrated the effectiveness of our proposed algorithm. Then, the proposed algorithm is presented to design a butterfly-shaped microstrip patch antenna. Combined with the HFSS solver, a butterfly-shaped patch antenna with a bandwidth of about 40.1% is designed by using the proposed OMSPSO. The return loss of the butterfly-shaped antenna is greater than 10 d B between 4.15 and 6.36 GHz. The antenna can serve simultaneously for the high-speed wireless computer networks(5.15–5.35 GHz) and the RFID systems(5.8 GHz).展开更多
An integer linear bilevel programming problem is firstly transformed into a binary linear bilevel programming problem, and then converted into a single-level binary implicit programming. An orthogonal genetic algorith...An integer linear bilevel programming problem is firstly transformed into a binary linear bilevel programming problem, and then converted into a single-level binary implicit programming. An orthogonal genetic algorithm is developed for solving the binary linear implicit programming problem based on the orthogonal design. The orthogonal design with the factor analysis, an experimental design method is applied to the genetic algorithm to make the algorithm more robust, statistical y sound and quickly convergent. A crossover operator formed by the orthogonal array and the factor analysis is presented. First, this crossover operator can generate a smal but representative sample of points as offspring. After al of the better genes of these offspring are selected, a best combination among these offspring is then generated. The simulation results show the effectiveness of the proposed algorithm.展开更多
A quadratic bilevel programming problem is transformed into a single level complementarity slackness problem by applying Karush-Kuhn-Tucker（KKT） conditions.To cope with the complementarity constraints,a binary encod...A quadratic bilevel programming problem is transformed into a single level complementarity slackness problem by applying Karush-Kuhn-Tucker（KKT） conditions.To cope with the complementarity constraints,a binary encoding scheme is adopted for KKT multipliers,and then the complementarity slackness problem is simplified to successive quadratic programming problems,which can be solved by many algorithms available.Based on 0-1 binary encoding,an orthogonal genetic algorithm,in which the orthogonal experimental design with both two-level orthogonal array and factor analysis is used as crossover operator,is proposed.Numerical experiments on 10 benchmark examples show that the orthogonal genetic algorithm can find global optimal solutions of quadratic bilevel programming problems with high accuracy in a small number of iterations.展开更多
Aimed at the uncertain characteristics of discrete logistics network design,an interval hierarchical triangular uncertain OD demand model based on interval demand and network flow is presented.Under consideration of t...Aimed at the uncertain characteristics of discrete logistics network design,an interval hierarchical triangular uncertain OD demand model based on interval demand and network flow is presented.Under consideration of the system profit,the uncertain demand of logistics network is measured by interval variables and interval parameters,and an interval planning model of discrete logistics network is established.The risk coefficient and maximum constrained deviation are defined to realize the certain transformation of the model.By integrating interval algorithm and genetic algorithm,an interval hierarchical optimal genetic algorithm is proposed to solve the model.It is shown by a tested example that in the same scenario condition an interval solution[3275.3,3 603.7]can be obtained by the model and algorithm which is obviously better than the single precise optimal solution by stochastic or fuzzy algorithm,so it can be reflected that the model and algorithm have more stronger operability and the solution result has superiority to scenario decision.展开更多
基金Projects(51774054,51974050)supported by the National Natural Science Foundation of China。
文摘Due to the current trend towards lightweight design in automotive industry,hollow stepped gear shafts for automobile and its radial forging process are widely investigated.Utilizing coupled finite element thermo-mechanical model,radial forging process of a hollow stepped gear shaft for automobile was simulated.The optimal combination of three process parameters including initial temperature,rotation rate and radial reduction was also selected using orthogonal design method.To examine the strain inhomogeneity of the forging workpiece,the strain inhomogeneity factor was introduced.The results reveal that the maximum effective strain and the minimum effective strain appeared in the outermost and innermost zones of different cross sections for the hollow stepped gear shaft,respectively.Optimal forging parameters are determined as a combination of initial temperature of 780°C,rotation rate of 21°/stroke and radial reduction of 3 mm.
基金supported by the Hunan Province Distinguished Ph.D. Innovation Fund (CX2012B018)the National University of Defense Technology Distinguished Ph.D. Innovation Fund (B120403)
文摘Orthogonal waveform design is quite an important issue for waveform diversity systems. A chaos based method for the orthogonal discrete frequency coding waveform （DFCW） design is proposed to increase the insufficient orthogonal waveform number and their finite coding length. Premises for chaos choosing and the frequency quantification method are discussed to obtain the best correlation properties. Simulation results show the validity of the theoretic analysis.
基金Projects(50934002,51074013,51104100)supported by the National Natural Science Foundation of ChinaProject(IRT0950)supported by the Program for Changjiang Scholars and Innovative Research Team in University of China
文摘Room and pillar sizes are key factors for safe mining and ore recovery in open-stope mining. To investigate the influence of room and pillar configurations on stope stability in highly fractured and weakened areas, an orthogonal design with two factors, three levels and nine runs was proposed, followed by three-dimensional numerical simulation using ANSYS and FLAC3~. Results show that surface settlement after excavation is concentrically ringed, and increases with the decrease of pillar width and distances to stope gobs. In the meantime, the ore-control fault at the ore-rock boundary and the fractured argillaceous dolomite with intercalated slate at the hanging wall deteriorate the roof settlement. Additionally, stope stability is challenged due to pillar rheological yield and stress concentration, and both are induced by redistribution of stress and plastic zones after mining. Following an objective function and a constraint function, room and pillar configuration with widths of 14 m and 16 m, respectively, is presented as the optimization for improving the ore recovery rate while maintaining a safe working environment.
基金Project(51822803)supported by the National Natural Science Foundation of ChinaProject(2019JJ50688)supported by Hunan Provincial Natural Science Foundation,China+1 种基金Project(kq1905005)supported by Training Program for Excellent Young Innovators of Changsha,ChinaProject(CX20210775)supported by Hunan Provincial Innovative Foundation for Postgraduates,China。
文摘Wind barriers have attracted significant attention as an effective measure to ensure train safety under crosswinds.However,in past decades,the influence of structural parameters such as the height and ventilation ratio of wind barriers on the difference of the average pressure coefficient between the train windward and leeward surface(ΔCp)has not been fully investigated.To determine the influence of the interaction among the three factors,namely the wind barrier height(H),ventilation ratio(R),and distance to the train(D),twenty five numerical simulation cases with different structural parameters were considered based on an orthogonal design.The shear stress transfer(SST)k-ωturbulent model was employed to calculate the wind pressure coefficients,and the calculation accuracy was validated by using wind tunnel experiments.The results indicated that with an increase in R,ΔCp first decreased and then increased,andΔCp decreased while D increased.Moreover,with the increase in H,ΔCp first increased and then decreased.Therefore,these three factors must be considered during the installation of wind barriers.Furthermore,according to a range analysis(judging the relative importance of the three factors intuitively),the three factors were ranked in the following order:R>H>D.Based on a variance analysis,R was found to be of high significance toΔCp,followed by H,which was significant,whereas D had relatively insignificant influence.Finally,the optimal values of R and H were determined to be 20%and 110 mm,respectively.And when R=40%,H=85 mm,the train was relatively unsafe under these such conditions.The findings of this study provide significant guidance for the structural design of wind barriers.
基金Project(61105067)supported by the National Natural Science Foundation of China
文摘A new multi-species particle swarm optimization with a two-level hierarchical topology and the orthogonal learning strategy(OMSPSO) is proposed, which enhances the global search ability of particles and increases their convergence rates. The numerical results on 10 benchmark functions demonstrated the effectiveness of our proposed algorithm. Then, the proposed algorithm is presented to design a butterfly-shaped microstrip patch antenna. Combined with the HFSS solver, a butterfly-shaped patch antenna with a bandwidth of about 40.1% is designed by using the proposed OMSPSO. The return loss of the butterfly-shaped antenna is greater than 10 d B between 4.15 and 6.36 GHz. The antenna can serve simultaneously for the high-speed wireless computer networks(5.15–5.35 GHz) and the RFID systems(5.8 GHz).
基金supported by the Fundamental Research Funds for the Central Universities(K50511700004)the Natural Science Basic Research Plan in Shaanxi Province of China(2013JM1022)
文摘An integer linear bilevel programming problem is firstly transformed into a binary linear bilevel programming problem, and then converted into a single-level binary implicit programming. An orthogonal genetic algorithm is developed for solving the binary linear implicit programming problem based on the orthogonal design. The orthogonal design with the factor analysis, an experimental design method is applied to the genetic algorithm to make the algorithm more robust, statistical y sound and quickly convergent. A crossover operator formed by the orthogonal array and the factor analysis is presented. First, this crossover operator can generate a smal but representative sample of points as offspring. After al of the better genes of these offspring are selected, a best combination among these offspring is then generated. The simulation results show the effectiveness of the proposed algorithm.
基金supported by the National Natural Science Foundation of China (60873099)
文摘A quadratic bilevel programming problem is transformed into a single level complementarity slackness problem by applying Karush-Kuhn-Tucker（KKT） conditions.To cope with the complementarity constraints,a binary encoding scheme is adopted for KKT multipliers,and then the complementarity slackness problem is simplified to successive quadratic programming problems,which can be solved by many algorithms available.Based on 0-1 binary encoding,an orthogonal genetic algorithm,in which the orthogonal experimental design with both two-level orthogonal array and factor analysis is used as crossover operator,is proposed.Numerical experiments on 10 benchmark examples show that the orthogonal genetic algorithm can find global optimal solutions of quadratic bilevel programming problems with high accuracy in a small number of iterations.
基金Project(51178061)supported by the National Natural Science Foundation of ChinaProject(2010FJ6016)supported by Hunan Provincial Science and Technology,China+1 种基金Project(12C0015)supported by Scientific Research Fund of Hunan Provincial Education Department,ChinaProject(13JJ3072)supported by Hunan Provincial Natural Science Foundation of China
文摘Aimed at the uncertain characteristics of discrete logistics network design,an interval hierarchical triangular uncertain OD demand model based on interval demand and network flow is presented.Under consideration of the system profit,the uncertain demand of logistics network is measured by interval variables and interval parameters,and an interval planning model of discrete logistics network is established.The risk coefficient and maximum constrained deviation are defined to realize the certain transformation of the model.By integrating interval algorithm and genetic algorithm,an interval hierarchical optimal genetic algorithm is proposed to solve the model.It is shown by a tested example that in the same scenario condition an interval solution[3275.3,3 603.7]can be obtained by the model and algorithm which is obviously better than the single precise optimal solution by stochastic or fuzzy algorithm,so it can be reflected that the model and algorithm have more stronger operability and the solution result has superiority to scenario decision.
