The similarity computations for fuzzy membership function pairs were carried out.Fuzzy number related knowledge was introduced,and conventional similarity was compared with distance based similarity measure.The useful...The similarity computations for fuzzy membership function pairs were carried out.Fuzzy number related knowledge was introduced,and conventional similarity was compared with distance based similarity measure.The usefulness of the proposed similarity measure was verified.The results show that the proposed similarity measure could be applied to ordinary fuzzy membership functions,though it was not easy to design.Through conventional results on the calculation of similarity for fuzzy membership pair,fuzzy membership-crisp pair and crisp-crisp pair were carried out.The proposed distance based similarity measure represented rational performance with the heuristic point of view.Furthermore,troublesome in fuzzy number based similarity measure for abnormal universe of discourse case was discussed.Finally,the similarity measure computation for various membership function pairs was discussed with other conventional results.展开更多
Deformation prediction and the analysis of underground goaf are important to the safe and efficient recovery of residual ore when shifting from open-pit mining to underground mining.To address the comprehensive proble...Deformation prediction and the analysis of underground goaf are important to the safe and efficient recovery of residual ore when shifting from open-pit mining to underground mining.To address the comprehensive problem of stability in the double mined-out area of the Tong-Lv-Shan(TLS)mine,which employed the dry stacked gangue technology,this paper applies the function fitting theory and a regression analysis method to screen the sensitive interval of four influencing factors based on single-factor experiments and the numerical simulation software FLAC3D.The influencing factors of the TLS mine consist of the column thickness(d),gob area span(D),boundary pillar thickness(h)and height of tailing gangue(H).The fitting degree between the four factors and the displacement of the gob roof(W)is reasonable because the correlation coefficient(R2)is greater than0.9701.After establishing29groups that satisfy the principles of Box-Behnken design(BBD),the dry gangue tailings process was re-simulated for the selected sensitive interval.Using a combination of an analysis of variance(ANOVA),regression equations and a significance analysis,the prediction results of the response surface methodology(RSM)show that the significant degree for the stability of the mined-out area for the factors satisfies the relationship of h>D>d>H.The importance of the four factors cannot be disregarded in a comparison of the prediction results of the engineering test stope in the TLS mine.By comparing the data of monitoring points and function prediction,the proposed method has shown promising results,and the prediction accuracy of RSM model is acceptable.The relative errors of the two test stopes are1.67%and3.85%,respectively,which yield satisfactory reliability and reference values for the mines.展开更多
Inspired by the idea that bionic non-smooth surfaces(BNSS) can reduce fluid adhesion and resistance, and the effect of bionic V-riblet non-smooth structure arranged in tire tread pattern grooves surface on anti-hydrop...Inspired by the idea that bionic non-smooth surfaces(BNSS) can reduce fluid adhesion and resistance, and the effect of bionic V-riblet non-smooth structure arranged in tire tread pattern grooves surface on anti-hydroplaning performance was investigated by using computational fluid dynamics(CFD). The physical model of the object(model of V-riblet surface distribution, hydroplaning model) and SST k-ω turbulence model were established for numerical analysis of tire hydroplaning. With the help of a orthogonal table L16(45), the parameters of V-riblet structure design compared to the smooth structure were analyzed, and obtained the priority level of the experimental factors as well as the best combination within the scope of the experiment. The simulation results show that V-riblet structure can reduce water flow resistance by disturbing the eddy movement in boundary layers. Then, the preferred type of V-riblet non-smooth structure was arranged on the bottom of tire grooves for hydroplaning performance analysis. The results show that bionic V-riblet non-smooth structure can effectively increase hydroplaning velocity and improve tire anti-hydroplaning performance. Bionic design of tire tread pattern grooves is a good way to promote anti-hydroplaning performance without increasing additional groove space, so that tire grip performance and roll noise are avoided due to grooves space enlargement.展开更多
According to the actual engineering problem that the precise load model of shield machine is difficult to achieve,a design method of sliding mode robust controller oriented to the automatic rectification of shield mac...According to the actual engineering problem that the precise load model of shield machine is difficult to achieve,a design method of sliding mode robust controller oriented to the automatic rectification of shield machine was proposed. Firstly,the nominal load model of shield machine and the ranges of model parameters were obtained by the soil mechanics parameters of certain geological conditions and the messages of the self-learning of shield machine by tunneling for previous segments. Based on this rectification mechanism model with known ranges of parameters,a sliding mode robust controller was proposed. Finally,the simulation analysis was developed to verify the effectiveness of the proposed controller. The simulation results show that the sliding mode robust controller can be implemented in the attitude rectification process of the shield machine and it has stronger robustness to overcome the soil disturbance.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
Under the condition of the designated collection ratio and the interfused ratio of mullock, to ensure the least energy consumption, the parameters of collecting head （the feed speed, the axes height of collecting hea...Under the condition of the designated collection ratio and the interfused ratio of mullock, to ensure the least energy consumption, the parameters of collecting head （the feed speed, the axes height of collecting head, and the rotate speed） are chosen as the optimized parameters. According to the force on the cutting pick, the collecting size of the cobalt crust and bedrock and the optimized energy consumption of the collecting head, the optimized design model of collecting head is built. Taking two hundred groups seabed microtopography for grand in the range of depth displacement from 4.5 to 5.5 era, then making use of the improved simulated annealing genetic algorithm （SAGA）, the corresponding optimized result can be obtained. At the same time, in order to speed up the controlling of collecting head, the optimization results are analyzed using the regression analysis method, and the conclusion of the second parameter of the seabed microtopography is drawn.展开更多
The application of new-designed levitation controller requires extensive validation prior to enter into commercial service. However, huge mounts of approximations and assumptions lead the theoretical analysis away fro...The application of new-designed levitation controller requires extensive validation prior to enter into commercial service. However, huge mounts of approximations and assumptions lead the theoretical analysis away from the engineering practice. The experimental methods are time-consuming and financial expensive, even unrealizable due to the lack of suitable sensors. Numerical simulations can bridge the gap between the theoretical analysis and experimental techniques. A complete overall dynamic model of maglev levitation system is derived in this work, which includes the simple-supported bridges, the calculation of electromagnetic force with more details, the stress of levitation modules and the cabin. Based on the aforementioned model, it shows that the inherent nonlinearity, inner coupling, misalignments between the sensors and actuators, and self-excited vibration are the main issues that should be considered during the design process of controller. Then, the backstepping controller based on the mathematical model of the module with reasonable simplifications is proposed, and the stability proofs are listed. To show the advantage of controller, two numerical simulation experiments are carried out. Finally, the results illustrating closed-loop performance are provided.展开更多
Parametric modeling of the impeller which drove a small wind device was built by knowledge fusion technology.NACA2410 airfoil blade was created by KF language.Using technology of UG/KF secondary development for the au...Parametric modeling of the impeller which drove a small wind device was built by knowledge fusion technology.NACA2410 airfoil blade was created by KF language.Using technology of UG/KF secondary development for the automatic modeling of wind turbine blade,the program can read in the airfoil data files automatically and the impeller model entity can be generated automatically.In order to modify the model,the aerodynamic characteristics of the impeller were analyzed for getting aerodynamic parameters by Fluent.The maximum force torch and best parameters of impeller were calculated.A physical prototype impeller was manufactured and the correctness of the design was verified,and the error of force torch between simulation and experimental results is about 10%.Parameterization design of the impeller model greatly improves the efficiency of modeling and flexibility of the CAD system.展开更多
Cam profiles play an important part in the performance of cam mechanisms. Syntheses of cam profile designs and dynamics of cam designs are studied at first. Then, a cam profile design optimization model based on the s...Cam profiles play an important part in the performance of cam mechanisms. Syntheses of cam profile designs and dynamics of cam designs are studied at first. Then, a cam profile design optimization model based on the six order classical spline and single DOF(degree of freedom) dynamic model of single-dwell cam mechanisms is developed. And dynamic constraints such as jumps and vibrations of followers are considered. This optimization model, with many advantages such as universalities of applications, conveniences to operations and good performances in improving kinematic and dynamic properties of cam mechanisms, is good except for the discontinuity of jerks at the end knots of cam profiles which will cause vibrations of cam systems. However, the optimization is improved by combining the six order classical spline with general polynomial spline which is the so-called "trade-offs". Finally, improved optimization is proven to have a better performance in designing cam profiles.展开更多
The inner relationship between Markov random field(MRF) and Markov chain random field(MCRF) is discussed. MCRF is a special MRF for dealing with high-order interactions of sparse data. It consists of a single spatial ...The inner relationship between Markov random field(MRF) and Markov chain random field(MCRF) is discussed. MCRF is a special MRF for dealing with high-order interactions of sparse data. It consists of a single spatial Markov chain(SMC) that can move in the whole space. Generally, the theoretical backbone of MCRF is conditional independence assumption, which is a way around the problem of knowing joint probabilities of multi-points. This so-called Naive Bayes assumption should not be taken lightly and should be checked whenever possible because it is mathematically difficult to prove. Rather than trap in this independence proving, an appropriate potential function in MRF theory is chosen instead. The MCRF formulas are well deduced and the joint probability of MRF is presented by localization approach, so that the complicated parameter estimation algorithm and iteration process can be avoided. The MCRF model is then applied to the lithofacies identification of a region and compared with triplex Markov chain(TMC) simulation. Analyses show that the MCRF model will not cause underestimation problem and can better reflect the geological sedimentation process.展开更多
For the purpose of improving efficiency and realizing start–stop function, an electric oil pump(EOP) is integrated into an 8-speed automatic transmission(AT). A mathematical model is built to calculate the transmissi...For the purpose of improving efficiency and realizing start–stop function, an electric oil pump(EOP) is integrated into an 8-speed automatic transmission(AT). A mathematical model is built to calculate the transmission power loss and the hydraulic system leakage. Based on this model, a flow-based control strategy is developed for EOP to satisfy the system flow requirement. This control strategy is verified through the forward driving simulation. The results indicate that there is a best combination for the size of mechanical oil pump(MOP) and EOP in terms of minimum energy consumption. In order to get a quick and smooth starting process, control strategies of the EOP and the on-coming clutch are proposed. The test environment on a prototype vehicle is built to verify the feasibility of the integrated EOP and its control strategies. The results show that the selected EOP can satisfy the flow requirement and a quick and smooth starting performance is achieved in the start–stop function. This research has a high value for the forward design of EOP in automatic transmissions with respect to efficiency improvement and start–stop function.展开更多
Similarity measure construction has been proposed as fault detection of flight test method in order to obtain the primary control surface stuck and the combination stuck of primary control.Similarity measures were obt...Similarity measure construction has been proposed as fault detection of flight test method in order to obtain the primary control surface stuck and the combination stuck of primary control.Similarity measures were obtained through analyzing the certainty and uncertainty of fuzzy membership functions,which were designed based on well-known Hamming distance.It was applied to the fault detection of primary control surface stuck of uninhabited aerial vehicle(UAV).At post-failure control surface,if the UAV is controllable and trimmable using other control surfaces,the UAV is able to fly or return to the safety region through reconfiguration of flight control system.To detect the fault,similarity measure computations were carried out.This result could be applicable with the real-time parameter estimation method.By monitoring the value of coefficients due to the control surface deviation,it becomes aware that the control surface fault occurs or not.The control surface stuck position and value were separated by comparing the trim value with the reference value.This is the advantage of increasing in reliability without adding sensors or with additional low cost.展开更多
In order to improve the strength and stiffness of shield cutterhead, the method of fuzzy mathematics theory in combination with the finite element analysis is adopted. An optimal design model of structural parameters ...In order to improve the strength and stiffness of shield cutterhead, the method of fuzzy mathematics theory in combination with the finite element analysis is adopted. An optimal design model of structural parameters for shield cutterhead is formulated,based on the complex engineering technical requirements. In the model, as the objective function of the model is a composite function of the strength and stiffness, the response surface method is applied to formulate the approximate function of objective function in order to reduce the solution scale of optimal problem. A multi-objective genetic algorithm is used to solve the cutterhead structure design problem and the change rule of the stress-strain with various structural parameters as well as their optimal values were researched under specific geological conditions. The results show that compared with original cutterhead structure scheme, the obtained optimal scheme of the cutterhead structure can greatly improve the strength and stiffness of the cutterhead, which can be seen from the reduction of its maximum equivalent stress by 21.2%, that of its maximum deformation by 0.75%, and that of its mass by 1.04%.展开更多
In order to realize the computer aided design of AT shifting element schemes, a mathematical model of shifting element schemes which can be easily identified by computers was built. Taking the transmission ratio seque...In order to realize the computer aided design of AT shifting element schemes, a mathematical model of shifting element schemes which can be easily identified by computers was built. Taking the transmission ratio sequence as an optimization objective and simple shifting logic between adjacent gears through operating only one shifting element as a constraint condition, a fitness function of shifting element schemes was proposed. ZF-8AT shifting element schemes were optimized based on GA work-box of MATLAB, and the feasibility of the optimization algorithm was verified.展开更多
Most modern tall buildings using lighter construction materials are more flexible, which can lead to excessive wind-induced vibrations resulting in occupant discomfort and structural unsafety. It is necessary to predi...Most modern tall buildings using lighter construction materials are more flexible, which can lead to excessive wind-induced vibrations resulting in occupant discomfort and structural unsafety. It is necessary to predict and mitigate such wind-induced vibration at the preliminary design stage. Fluctuating across and along-wind loads acting on a tall building that could not be formulated theoretically were simulated numerically in the time domain using known across and along-wind load spectra. These simulated wind loads were used to estimate the across and along-wind responses of a tall building, which are less narrow-banded processes, based on the state space variable approach. The simulated across-wind response of root-mean-square value(0.0047) and that of KAREEM's(0.0040) and the simulated along-wind response of root-mean-square value(0.021) and that of SOLARI's(0.027) were compared. It is found that these are good approximations of closed form responses. Therefore, these numerically simulated across and along-wind loads can be used for across and along-wind responses estimation for the wind-resistant design of a tall building at the preliminary design stage.展开更多
基金Project(2010-0020163) supported by Priority Research Centers Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education,Science and Technology
文摘The similarity computations for fuzzy membership function pairs were carried out.Fuzzy number related knowledge was introduced,and conventional similarity was compared with distance based similarity measure.The usefulness of the proposed similarity measure was verified.The results show that the proposed similarity measure could be applied to ordinary fuzzy membership functions,though it was not easy to design.Through conventional results on the calculation of similarity for fuzzy membership pair,fuzzy membership-crisp pair and crisp-crisp pair were carried out.The proposed distance based similarity measure represented rational performance with the heuristic point of view.Furthermore,troublesome in fuzzy number based similarity measure for abnormal universe of discourse case was discussed.Finally,the similarity measure computation for various membership function pairs was discussed with other conventional results.
基金Project(2017YFC0602902) supported by the National Science and Technology Pillar Program during the 13th Five-Year Plan Period,ChinaProject(2015CX005) supported by the Innovation Driven Plan of Central South University,ChinaProject(2016zzts445) supported by the Fundamental Research Funds for the Central Universities,China
文摘Deformation prediction and the analysis of underground goaf are important to the safe and efficient recovery of residual ore when shifting from open-pit mining to underground mining.To address the comprehensive problem of stability in the double mined-out area of the Tong-Lv-Shan(TLS)mine,which employed the dry stacked gangue technology,this paper applies the function fitting theory and a regression analysis method to screen the sensitive interval of four influencing factors based on single-factor experiments and the numerical simulation software FLAC3D.The influencing factors of the TLS mine consist of the column thickness(d),gob area span(D),boundary pillar thickness(h)and height of tailing gangue(H).The fitting degree between the four factors and the displacement of the gob roof(W)is reasonable because the correlation coefficient(R2)is greater than0.9701.After establishing29groups that satisfy the principles of Box-Behnken design(BBD),the dry gangue tailings process was re-simulated for the selected sensitive interval.Using a combination of an analysis of variance(ANOVA),regression equations and a significance analysis,the prediction results of the response surface methodology(RSM)show that the significant degree for the stability of the mined-out area for the factors satisfies the relationship of h>D>d>H.The importance of the four factors cannot be disregarded in a comparison of the prediction results of the engineering test stope in the TLS mine.By comparing the data of monitoring points and function prediction,the proposed method has shown promising results,and the prediction accuracy of RSM model is acceptable.The relative errors of the two test stopes are1.67%and3.85%,respectively,which yield satisfactory reliability and reference values for the mines.
基金Project(51405201)supported by the National Natural Science Foundation of ChinaProject(1291120046)supported by the Jiangsu University Advanced Talents Initial Funding,China+1 种基金Project(QC201303)supported by the Open Fund of Automotive Engineering Key Laboratory,ChinaProject(2014M551509)supported by the China Postdoctoral Science Foundation
文摘Inspired by the idea that bionic non-smooth surfaces(BNSS) can reduce fluid adhesion and resistance, and the effect of bionic V-riblet non-smooth structure arranged in tire tread pattern grooves surface on anti-hydroplaning performance was investigated by using computational fluid dynamics(CFD). The physical model of the object(model of V-riblet surface distribution, hydroplaning model) and SST k-ω turbulence model were established for numerical analysis of tire hydroplaning. With the help of a orthogonal table L16(45), the parameters of V-riblet structure design compared to the smooth structure were analyzed, and obtained the priority level of the experimental factors as well as the best combination within the scope of the experiment. The simulation results show that V-riblet structure can reduce water flow resistance by disturbing the eddy movement in boundary layers. Then, the preferred type of V-riblet non-smooth structure was arranged on the bottom of tire grooves for hydroplaning performance analysis. The results show that bionic V-riblet non-smooth structure can effectively increase hydroplaning velocity and improve tire anti-hydroplaning performance. Bionic design of tire tread pattern grooves is a good way to promote anti-hydroplaning performance without increasing additional groove space, so that tire grip performance and roll noise are avoided due to grooves space enlargement.
基金Project(2007CB714006) supported by the National Basic Research Program of China
文摘According to the actual engineering problem that the precise load model of shield machine is difficult to achieve,a design method of sliding mode robust controller oriented to the automatic rectification of shield machine was proposed. Firstly,the nominal load model of shield machine and the ranges of model parameters were obtained by the soil mechanics parameters of certain geological conditions and the messages of the self-learning of shield machine by tunneling for previous segments. Based on this rectification mechanism model with known ranges of parameters,a sliding mode robust controller was proposed. Finally,the simulation analysis was developed to verify the effectiveness of the proposed controller. The simulation results show that the sliding mode robust controller can be implemented in the attitude rectification process of the shield machine and it has stronger robustness to overcome the soil disturbance.
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(50875265) supported by the National Natural Science Foundation of ChinaProject(20080440992) supported by the Postdoctoral Science Foundation of ChinaProject(2009SK3159) supported by the Technology Support Plan of Hunan Province,China
文摘Under the condition of the designated collection ratio and the interfused ratio of mullock, to ensure the least energy consumption, the parameters of collecting head （the feed speed, the axes height of collecting head, and the rotate speed） are chosen as the optimized parameters. According to the force on the cutting pick, the collecting size of the cobalt crust and bedrock and the optimized energy consumption of the collecting head, the optimized design model of collecting head is built. Taking two hundred groups seabed microtopography for grand in the range of depth displacement from 4.5 to 5.5 era, then making use of the improved simulated annealing genetic algorithm （SAGA）, the corresponding optimized result can be obtained. At the same time, in order to speed up the controlling of collecting head, the optimization results are analyzed using the regression analysis method, and the conclusion of the second parameter of the seabed microtopography is drawn.
基金Projects(60404003,11202230)supported by the National Natural Science Foundation of China
文摘The application of new-designed levitation controller requires extensive validation prior to enter into commercial service. However, huge mounts of approximations and assumptions lead the theoretical analysis away from the engineering practice. The experimental methods are time-consuming and financial expensive, even unrealizable due to the lack of suitable sensors. Numerical simulations can bridge the gap between the theoretical analysis and experimental techniques. A complete overall dynamic model of maglev levitation system is derived in this work, which includes the simple-supported bridges, the calculation of electromagnetic force with more details, the stress of levitation modules and the cabin. Based on the aforementioned model, it shows that the inherent nonlinearity, inner coupling, misalignments between the sensors and actuators, and self-excited vibration are the main issues that should be considered during the design process of controller. Then, the backstepping controller based on the mathematical model of the module with reasonable simplifications is proposed, and the stability proofs are listed. To show the advantage of controller, two numerical simulation experiments are carried out. Finally, the results illustrating closed-loop performance are provided.
基金Project(gjd-09041)supported by the Natural Science Foundation of Shanghai Municipal Education Commission,China
文摘Parametric modeling of the impeller which drove a small wind device was built by knowledge fusion technology.NACA2410 airfoil blade was created by KF language.Using technology of UG/KF secondary development for the automatic modeling of wind turbine blade,the program can read in the airfoil data files automatically and the impeller model entity can be generated automatically.In order to modify the model,the aerodynamic characteristics of the impeller were analyzed for getting aerodynamic parameters by Fluent.The maximum force torch and best parameters of impeller were calculated.A physical prototype impeller was manufactured and the correctness of the design was verified,and the error of force torch between simulation and experimental results is about 10%.Parameterization design of the impeller model greatly improves the efficiency of modeling and flexibility of the CAD system.
文摘Cam profiles play an important part in the performance of cam mechanisms. Syntheses of cam profile designs and dynamics of cam designs are studied at first. Then, a cam profile design optimization model based on the six order classical spline and single DOF(degree of freedom) dynamic model of single-dwell cam mechanisms is developed. And dynamic constraints such as jumps and vibrations of followers are considered. This optimization model, with many advantages such as universalities of applications, conveniences to operations and good performances in improving kinematic and dynamic properties of cam mechanisms, is good except for the discontinuity of jerks at the end knots of cam profiles which will cause vibrations of cam systems. However, the optimization is improved by combining the six order classical spline with general polynomial spline which is the so-called "trade-offs". Finally, improved optimization is proven to have a better performance in designing cam profiles.
基金Project(2011ZX05002-005-006) supported by the National Science and Technology Major Research Program during the Twelfth Five-Year Plan of China
文摘The inner relationship between Markov random field(MRF) and Markov chain random field(MCRF) is discussed. MCRF is a special MRF for dealing with high-order interactions of sparse data. It consists of a single spatial Markov chain(SMC) that can move in the whole space. Generally, the theoretical backbone of MCRF is conditional independence assumption, which is a way around the problem of knowing joint probabilities of multi-points. This so-called Naive Bayes assumption should not be taken lightly and should be checked whenever possible because it is mathematically difficult to prove. Rather than trap in this independence proving, an appropriate potential function in MRF theory is chosen instead. The MCRF formulas are well deduced and the joint probability of MRF is presented by localization approach, so that the complicated parameter estimation algorithm and iteration process can be avoided. The MCRF model is then applied to the lithofacies identification of a region and compared with triplex Markov chain(TMC) simulation. Analyses show that the MCRF model will not cause underestimation problem and can better reflect the geological sedimentation process.
基金Project(51405010)supported by the National Natural Science Foundation of ChinaProject(2011BAG09B00)supported by the National Science and Technology Support Program of China
文摘For the purpose of improving efficiency and realizing start–stop function, an electric oil pump(EOP) is integrated into an 8-speed automatic transmission(AT). A mathematical model is built to calculate the transmission power loss and the hydraulic system leakage. Based on this model, a flow-based control strategy is developed for EOP to satisfy the system flow requirement. This control strategy is verified through the forward driving simulation. The results indicate that there is a best combination for the size of mechanical oil pump(MOP) and EOP in terms of minimum energy consumption. In order to get a quick and smooth starting process, control strategies of the EOP and the on-coming clutch are proposed. The test environment on a prototype vehicle is built to verify the feasibility of the integrated EOP and its control strategies. The results show that the selected EOP can satisfy the flow requirement and a quick and smooth starting performance is achieved in the start–stop function. This research has a high value for the forward design of EOP in automatic transmissions with respect to efficiency improvement and start–stop function.
基金Project(20110018394) supported by Key Research Institute Program through the National Research Foundation (NRF) of Korea
文摘Similarity measure construction has been proposed as fault detection of flight test method in order to obtain the primary control surface stuck and the combination stuck of primary control.Similarity measures were obtained through analyzing the certainty and uncertainty of fuzzy membership functions,which were designed based on well-known Hamming distance.It was applied to the fault detection of primary control surface stuck of uninhabited aerial vehicle(UAV).At post-failure control surface,if the UAV is controllable and trimmable using other control surfaces,the UAV is able to fly or return to the safety region through reconfiguration of flight control system.To detect the fault,similarity measure computations were carried out.This result could be applicable with the real-time parameter estimation method.By monitoring the value of coefficients due to the control surface deviation,it becomes aware that the control surface fault occurs or not.The control surface stuck position and value were separated by comparing the trim value with the reference value.This is the advantage of increasing in reliability without adding sensors or with additional low cost.
基金Project(51074180) supported by the National Natural Science Foundation of ChinaProject(2012AA041801) supported by the National High Technology Research and Development Program of China+2 种基金Project(2007CB714002) supported by the National Basic Research Program of ChinaProject(2013GK3003) supported by the Technology Support Plan of Hunan Province,ChinaProject(2010FJ1002) supported by Hunan Science and Technology Major Program,China
文摘In order to improve the strength and stiffness of shield cutterhead, the method of fuzzy mathematics theory in combination with the finite element analysis is adopted. An optimal design model of structural parameters for shield cutterhead is formulated,based on the complex engineering technical requirements. In the model, as the objective function of the model is a composite function of the strength and stiffness, the response surface method is applied to formulate the approximate function of objective function in order to reduce the solution scale of optimal problem. A multi-objective genetic algorithm is used to solve the cutterhead structure design problem and the change rule of the stress-strain with various structural parameters as well as their optimal values were researched under specific geological conditions. The results show that compared with original cutterhead structure scheme, the obtained optimal scheme of the cutterhead structure can greatly improve the strength and stiffness of the cutterhead, which can be seen from the reduction of its maximum equivalent stress by 21.2%, that of its maximum deformation by 0.75%, and that of its mass by 1.04%.
基金Project(2011BAG09B00)supported by the National Science and Technology Support Program,China
文摘In order to realize the computer aided design of AT shifting element schemes, a mathematical model of shifting element schemes which can be easily identified by computers was built. Taking the transmission ratio sequence as an optimization objective and simple shifting logic between adjacent gears through operating only one shifting element as a constraint condition, a fitness function of shifting element schemes was proposed. ZF-8AT shifting element schemes were optimized based on GA work-box of MATLAB, and the feasibility of the optimization algorithm was verified.
基金Project(2011-0028567)supported by the National Research Foundation of Korea
文摘Most modern tall buildings using lighter construction materials are more flexible, which can lead to excessive wind-induced vibrations resulting in occupant discomfort and structural unsafety. It is necessary to predict and mitigate such wind-induced vibration at the preliminary design stage. Fluctuating across and along-wind loads acting on a tall building that could not be formulated theoretically were simulated numerically in the time domain using known across and along-wind load spectra. These simulated wind loads were used to estimate the across and along-wind responses of a tall building, which are less narrow-banded processes, based on the state space variable approach. The simulated across-wind response of root-mean-square value(0.0047) and that of KAREEM's(0.0040) and the simulated along-wind response of root-mean-square value(0.021) and that of SOLARI's(0.027) were compared. It is found that these are good approximations of closed form responses. Therefore, these numerically simulated across and along-wind loads can be used for across and along-wind responses estimation for the wind-resistant design of a tall building at the preliminary design stage.
