Di erential braking and active steering have already been integrated to overcome their shortcomings. However, existing research mainly focuses on two-axle vehicles and controllers are mostly designed to use one contro...Di erential braking and active steering have already been integrated to overcome their shortcomings. However, existing research mainly focuses on two-axle vehicles and controllers are mostly designed to use one control method to improve the other. Moreover, many experiments are needed to improve the robustness; therefore, these control methods are underutilized. This paper proposes an integrated control system specially designed for multi-axle vehicles, in which the desired lateral force and yaw moment of vehicles are determined by the sliding mode control algorithm. The output of the sliding mode control is distributed to the suitable wheels based on the abilities and potentials of the two control methods. Moreover, in this method, fewer experiments are needed, and the robustness and simultaneity are both guaranteed. To simplify the optimization system and to improve the computation speed, seven simple optimization subsystems are designed for the determination of control outputs on each wheel. The simulation results show that the proposed controller obviously enhances the stability of multi-axle trucks. The system improves 68% of the safe velocity, and its performance is much better than both di erential braking and active steering. This research proposes an integrated control system that can simultaneously invoke di erential braking and active steering of multi-axle vehicles to fully utilize the abilities and potentials of the two control methods.展开更多
During the historical period of securing a decisive victory in building a moderately prosperous society in all respects and striving for the great success of socialism with Chinese characteristics for a new era, the 1...During the historical period of securing a decisive victory in building a moderately prosperous society in all respects and striving for the great success of socialism with Chinese characteristics for a new era, the 19 th National Congress of the CPC put forward the signi cant deployment of rural vitalization strategy, drawing a great blueprint for the prospect of China's "three issues" of agriculture, rural areas, and farmers and acting as an important focus of these "three issues" in the future. This paper discussed the relationships between farmers' role di erentiation and ve objectives of the rural vitalization strategy on the basis of farmers' role di erentiation and conversion in the process of agriculture and countryside modernization and the interpretation of farmers' role di erentiation and the rural vitalization strategy. Based on the logical relationships between farmers' role di erentiation and the rural vitalization strategy, we discuss the e ective implementation of the rural vitalization strategy in terms of its targets, processes and e ectiveness evaluations. We also propose that the implementation of the rural vitalization strategy can only be implemented when farmers are given the rst priority as strategy subjects, farmers' wills are respected in the implementation process, and farmers' satisfaction is highlighted in the strategy implementation e ectiveness evaluations.展开更多
Static “self-optimising” control is an important concept, which provides a link between static optimisation and control. According to the concept, a dynamic control system could be configured in such a way that when...Static “self-optimising” control is an important concept, which provides a link between static optimisation and control. According to the concept, a dynamic control system could be configured in such a way that when a set of certain variables are maintained at their setpoints, the overall process operation is automatically optimal or near optimal at steady-state in the presence of disturbances. A novel approach using constrained gradient control to achieve “self-optimisation” has been proposed by Cao. However, for most process plants, the information required to get the gradient measure may not be available in real-time. In such cases, controlled variable selection has to be carried out based on measurable candidates. In this work, the idea of direct gradient control has been extended to controlled variable selection based on gradient sensitivity analysis (indirect gradient control). New criteria, which indicate the sensitivity of the gradient function to disturbances and implementation errors, have been derived for selection. The particular case study shows that the controlled variables selected by gradient sensitivity measures are able to achieve near optimal performance.展开更多
Implicit-explicit Runge-Kutta-Rosenbrock methods are proposed to solve nonlinear sti ordinary di erential equations by combining linearly implicit Rosenbrock methods with explicit Runge-Kutta methods.First,the general...Implicit-explicit Runge-Kutta-Rosenbrock methods are proposed to solve nonlinear sti ordinary di erential equations by combining linearly implicit Rosenbrock methods with explicit Runge-Kutta methods.First,the general order conditions up to order 3 are obtained.Then,for the nonlinear sti initial-value problems satisfying the one-sided Lipschitz condition and a class of singularly perturbed initial-value problems,the corresponding errors of the implicit-explicit methods are analysed.At last,some numerical examples are given to verify the validity of the obtained theoretical results and the e ectiveness of the methods.展开更多
We investigate the growth of solutions of the following complex linear di er-ential equation f″+A(z)f′+B(z)f=0,where A(z)and B(z)are analytic functions in -C-{z0},z0∈C.Some estimations of lower bounded of growth of...We investigate the growth of solutions of the following complex linear di er-ential equation f″+A(z)f′+B(z)f=0,where A(z)and B(z)are analytic functions in -C-{z0},z0∈C.Some estimations of lower bounded of growth of solutions of the di erential equation are obtained by using the concept of lower order.展开更多
The present paper is devoted to a preliminary study towards the establishment of an ergodic theory for stochastic di erential equations(SDEs)with less regular coecients and degenerate noises.These equations are often ...The present paper is devoted to a preliminary study towards the establishment of an ergodic theory for stochastic di erential equations(SDEs)with less regular coecients and degenerate noises.These equations are often derived as mesoscopic limits of complex or huge microscopic systems.By studying the associated Fokker-Planck equation(FPE),we prove the convergence of the time average of globally de ned weak solutions of such an SDE to the set of stationary measures of the FPE under Lyapunov conditions.In the case where the set of stationary measures consists of a single element,the unique stationary measure is shown to be physical.Similar convergence results for the solutions of the FPE are established as well.Some of our convergence results,while being special cases of those contained in Ji et al.(2019)for SDEs with periodic coecients,have weaken the required Lyapunov conditions and are of much simpli ed proofs.Applications to stochastic damping Hamiltonian systems and stochastic slow-fast systems are given.展开更多
目的探讨成骨细胞特异性钙黏蛋白(cadherin ectodomainⅡ,Cad-Ⅱ)涂布于同种异体脱钙骨基质材料(freeze-dried demineralized bone matrix,FDBM)对兔BMSCs黏附、增殖及成骨分化能力的影响。方法取4周龄日本大耳白兔10只,体重0.61～0.88...目的探讨成骨细胞特异性钙黏蛋白(cadherin ectodomainⅡ,Cad-Ⅱ)涂布于同种异体脱钙骨基质材料(freeze-dried demineralized bone matrix,FDBM)对兔BMSCs黏附、增殖及成骨分化能力的影响。方法取4周龄日本大耳白兔10只,体重0.61～0.88kg,雌雄不限,常规分离培养BMSCs。取第2代BMSCs(细胞密度1×106个/mL)分别与经Cad-Ⅱ修饰的FDBM(实验组)和未经Cad-Ⅱ修饰的FDBM(对照组)复合,行MTT检测细胞增殖能力,细胞黏附实验检测细胞上架率和上架数,倒置相差显微镜、扫描电镜及HE染色观察细胞生长情况。另取第2代BMSCs(细胞密度5×105个/mL)分别与经Cad-Ⅱ修饰的FDBM(实验组)和未经Cad-Ⅱ修饰的FDBM(对照组)复合培养,行ALP活性检测和骨钙素免疫组织化学染色观察细胞成骨分化情况。结果MTT检测发现BMSCs在经Cad-Ⅱ修饰的支架材料上能正常增殖,但与对照组比较差异无统计学意义(P>0.05)。实验组细胞上架率为87.41%±5.19%,明显高于对照组35.56%±1.75%(P<0.01);对照组每片材料细胞上架数平均为2.6×104个,实验组平均高达5.0×105个,明显多于对照组(P<0.05)。倒置相差显微镜、扫描电镜及HE染色观察均显示实验组支架上黏附细胞数量明显多于对照组。成骨诱导培养7d,实验组和对照组细胞均可表达骨钙素,具有成骨细胞表型;培养14d,实验组和对照组ALP活性分别为29.33±1.53和18.31±1.32,骨钙素免疫组织化学染色阳性率分别为83%±7%和56%±7%,两组比较差异均有统计学意义(P<0.01);与同组7、21d比较差异有统计学意义(P<0.01),7d与21d组间及组内比较差异均无统计学意义(P>0.05)。结论Cad-Ⅱ修饰的FDBM对BMSCs增殖无明显促进作用,但能提高细胞黏附性,并促进BMSCs向成骨细胞分化。展开更多
基金National Natural Science Foundation of China(Grant No.51505178)China Postdoctoral Science Foundation(Grant No.2014M561289)
文摘Di erential braking and active steering have already been integrated to overcome their shortcomings. However, existing research mainly focuses on two-axle vehicles and controllers are mostly designed to use one control method to improve the other. Moreover, many experiments are needed to improve the robustness; therefore, these control methods are underutilized. This paper proposes an integrated control system specially designed for multi-axle vehicles, in which the desired lateral force and yaw moment of vehicles are determined by the sliding mode control algorithm. The output of the sliding mode control is distributed to the suitable wheels based on the abilities and potentials of the two control methods. Moreover, in this method, fewer experiments are needed, and the robustness and simultaneity are both guaranteed. To simplify the optimization system and to improve the computation speed, seven simple optimization subsystems are designed for the determination of control outputs on each wheel. The simulation results show that the proposed controller obviously enhances the stability of multi-axle trucks. The system improves 68% of the safe velocity, and its performance is much better than both di erential braking and active steering. This research proposes an integrated control system that can simultaneously invoke di erential braking and active steering of multi-axle vehicles to fully utilize the abilities and potentials of the two control methods.
基金“Study on Farmers’Participation in the Management of Field Irrigation System:Resource Endowment,Organization Support,and Governance Performance,”National Natural Science Foundation of China Project(Code:71773092)“Studies on the Weakness of Poverty of Rural Residents in Closely Grouped Areas,”Social Science Foundation of Ministry of Education Project(Code:17YJA790102)
文摘During the historical period of securing a decisive victory in building a moderately prosperous society in all respects and striving for the great success of socialism with Chinese characteristics for a new era, the 19 th National Congress of the CPC put forward the signi cant deployment of rural vitalization strategy, drawing a great blueprint for the prospect of China's "three issues" of agriculture, rural areas, and farmers and acting as an important focus of these "three issues" in the future. This paper discussed the relationships between farmers' role di erentiation and ve objectives of the rural vitalization strategy on the basis of farmers' role di erentiation and conversion in the process of agriculture and countryside modernization and the interpretation of farmers' role di erentiation and the rural vitalization strategy. Based on the logical relationships between farmers' role di erentiation and the rural vitalization strategy, we discuss the e ective implementation of the rural vitalization strategy in terms of its targets, processes and e ectiveness evaluations. We also propose that the implementation of the rural vitalization strategy can only be implemented when farmers are given the rst priority as strategy subjects, farmers' wills are respected in the implementation process, and farmers' satisfaction is highlighted in the strategy implementation e ectiveness evaluations.
基金supported by the EPSRC UK under grant GR/R57324.
文摘Static “self-optimising” control is an important concept, which provides a link between static optimisation and control. According to the concept, a dynamic control system could be configured in such a way that when a set of certain variables are maintained at their setpoints, the overall process operation is automatically optimal or near optimal at steady-state in the presence of disturbances. A novel approach using constrained gradient control to achieve “self-optimisation” has been proposed by Cao. However, for most process plants, the information required to get the gradient measure may not be available in real-time. In such cases, controlled variable selection has to be carried out based on measurable candidates. In this work, the idea of direct gradient control has been extended to controlled variable selection based on gradient sensitivity analysis (indirect gradient control). New criteria, which indicate the sensitivity of the gradient function to disturbances and implementation errors, have been derived for selection. The particular case study shows that the controlled variables selected by gradient sensitivity measures are able to achieve near optimal performance.
基金The authors wish to thank the anonymous referees for their valuable comments and suggestions.The work is supported by the National Natural Science Foundation of China(Grant Nos.11671343,11701110)the Foundation for the Key Laboratory of Computational Physics,China(No.6142A05180103)the Scientific Research Fund of Science and Technology Department of Hunan Province in China(Grant No.2018WK4006).
文摘Implicit-explicit Runge-Kutta-Rosenbrock methods are proposed to solve nonlinear sti ordinary di erential equations by combining linearly implicit Rosenbrock methods with explicit Runge-Kutta methods.First,the general order conditions up to order 3 are obtained.Then,for the nonlinear sti initial-value problems satisfying the one-sided Lipschitz condition and a class of singularly perturbed initial-value problems,the corresponding errors of the implicit-explicit methods are analysed.At last,some numerical examples are given to verify the validity of the obtained theoretical results and the e ectiveness of the methods.
基金National Natural Science Foundation of China(11861023)the Foundation of Science and Technology project of Guizhou Province of China([2018]5769-05)。
文摘We investigate the growth of solutions of the following complex linear di er-ential equation f″+A(z)f′+B(z)f=0,where A(z)and B(z)are analytic functions in -C-{z0},z0∈C.Some estimations of lower bounded of growth of solutions of the di erential equation are obtained by using the concept of lower order.
基金The first author was supported by China Scholarship Council.The second author was supported by University of Alberta,and Natural Sciences and Engineering Research Council of Canada(Grant Nos.RGPIN-2018-04371 and DGECR-2018-00353)The third author was supported by Pacific Institute for the Mathematical Sciences-Canadian Statistical Sciences Institute Postdoctoral Fellowship,Pacific Institute for the Mathematical Sciences-Collaborative Research Group Grant,National Natural Science Foundation of China(Grant Nos.11771026 and 11471344)+2 种基金the Pacific Institute for the Mathematical Sciences-University of Washington site through National Science Foundation of USA(Grant No.DMS-1712701)The fourth author was supported by Natural Sciences and Engineering Research Council of Canada Discovery(Grant No.1257749)Pacific Institute for the Mathematical Sciences-Collaborative Research Group Grant,University of Alberta,and Jilin University.
文摘The present paper is devoted to a preliminary study towards the establishment of an ergodic theory for stochastic di erential equations(SDEs)with less regular coecients and degenerate noises.These equations are often derived as mesoscopic limits of complex or huge microscopic systems.By studying the associated Fokker-Planck equation(FPE),we prove the convergence of the time average of globally de ned weak solutions of such an SDE to the set of stationary measures of the FPE under Lyapunov conditions.In the case where the set of stationary measures consists of a single element,the unique stationary measure is shown to be physical.Similar convergence results for the solutions of the FPE are established as well.Some of our convergence results,while being special cases of those contained in Ji et al.(2019)for SDEs with periodic coecients,have weaken the required Lyapunov conditions and are of much simpli ed proofs.Applications to stochastic damping Hamiltonian systems and stochastic slow-fast systems are given.
文摘目的探讨成骨细胞特异性钙黏蛋白(cadherin ectodomainⅡ,Cad-Ⅱ)涂布于同种异体脱钙骨基质材料(freeze-dried demineralized bone matrix,FDBM)对兔BMSCs黏附、增殖及成骨分化能力的影响。方法取4周龄日本大耳白兔10只,体重0.61～0.88kg,雌雄不限,常规分离培养BMSCs。取第2代BMSCs(细胞密度1×106个/mL)分别与经Cad-Ⅱ修饰的FDBM(实验组)和未经Cad-Ⅱ修饰的FDBM(对照组)复合,行MTT检测细胞增殖能力,细胞黏附实验检测细胞上架率和上架数,倒置相差显微镜、扫描电镜及HE染色观察细胞生长情况。另取第2代BMSCs(细胞密度5×105个/mL)分别与经Cad-Ⅱ修饰的FDBM(实验组)和未经Cad-Ⅱ修饰的FDBM(对照组)复合培养,行ALP活性检测和骨钙素免疫组织化学染色观察细胞成骨分化情况。结果MTT检测发现BMSCs在经Cad-Ⅱ修饰的支架材料上能正常增殖,但与对照组比较差异无统计学意义(P>0.05)。实验组细胞上架率为87.41%±5.19%,明显高于对照组35.56%±1.75%(P<0.01);对照组每片材料细胞上架数平均为2.6×104个,实验组平均高达5.0×105个,明显多于对照组(P<0.05)。倒置相差显微镜、扫描电镜及HE染色观察均显示实验组支架上黏附细胞数量明显多于对照组。成骨诱导培养7d,实验组和对照组细胞均可表达骨钙素,具有成骨细胞表型;培养14d,实验组和对照组ALP活性分别为29.33±1.53和18.31±1.32,骨钙素免疫组织化学染色阳性率分别为83%±7%和56%±7%,两组比较差异均有统计学意义(P<0.01);与同组7、21d比较差异有统计学意义(P<0.01),7d与21d组间及组内比较差异均无统计学意义(P>0.05)。结论Cad-Ⅱ修饰的FDBM对BMSCs增殖无明显促进作用,但能提高细胞黏附性,并促进BMSCs向成骨细胞分化。
