This paper bursts the bondage of conventional no-burn thought, presents an optimum strategy permitting burn appear in grinding roughing stage, but the burning layer can be summed on the following finishing stage. On t...This paper bursts the bondage of conventional no-burn thought, presents an optimum strategy permitting burn appear in grinding roughing stage, but the burning layer can be summed on the following finishing stage. On the base of the basic grinding models, the objective function and constrained functions for the multiparameter optimum grinding models had been built in this paper. By the computer simulation, the nonlinear optimum grinding control parameters had been obtained, and the truth grinding process had been controlled by these parameters. The results of simulation and the experiments proved the exactitude of the optimum models and the feasibility of the optimum strategy. This paper had also created the precondition for the grinding automation, virtual grinding and intelligent grinding system for cylindrical grinding process.展开更多
In order to study the bending behavior of aluminum alloy 7050 thick plate during snake hot rolling, several coupled thermo-mechanical finite element(FE) models were established. Effects of different initial thicknesse...In order to study the bending behavior of aluminum alloy 7050 thick plate during snake hot rolling, several coupled thermo-mechanical finite element(FE) models were established. Effects of different initial thicknesses, pass reductions, speed ratios and offset distances on the bending value of the plate were analyzed. ‘Quasi smooth plate' and optimum offset distance were defined and quasi smooth plate could be acquired by adjusting offset distance, and then bending control equation was fitted. The results show that bending value of the plate as well as the extent of the increase grows with the increase of pass reduction and decrease of initial thickness; the bending value firstly increases and then keeps steady with the ascending speed ratio; the bending value can be reduced by enlarging the offset distance. The optimum offset distance varies for different rolling parameters and it is augmented with the increase of pass reduction and speed ratio and the decrease of initial thickness. A proper offset distance for different rolling parameters can be calculated by the bending control equation and this equation can be a guidance to acquire a quasi smooth plate. The FEM results agree well with experimental results.展开更多
An optimum PN guidance law for maneuvering target is developed using optimal control theory.By estimating the target position and setting the cost function,the guidance law can be deduced even without knowing the miss...An optimum PN guidance law for maneuvering target is developed using optimal control theory.By estimating the target position and setting the cost function,the guidance law can be deduced even without knowing the missile lateral acceleration.Since the quadratic cost function can make a compromise between the miss distance and the control constraint,the optimum guidance law obtained is more general.Also,introduced line of sight rate as the input,a practical form of this guidance law is derived.The simulation results show the effectiveness of the guidance laws.展开更多
青枯雷尔氏菌(Ralstonia solanacearum)引起芝麻青枯病,制约我国南方芝麻生产。为制定精准的药剂防治技术,在江西省南昌县连续4年建立病害观察圃,研究病害发生特点,选择芝麻连作田块,研究用药适期和筛选药剂。结果发现,芝麻青枯病多于...青枯雷尔氏菌(Ralstonia solanacearum)引起芝麻青枯病,制约我国南方芝麻生产。为制定精准的药剂防治技术,在江西省南昌县连续4年建立病害观察圃,研究病害发生特点,选择芝麻连作田块,研究用药适期和筛选药剂。结果发现,芝麻青枯病多于现蕾期前后开始发病,初花期病情指数增长率均最为急剧;芝麻定苗时进行药剂喷淋护根,初花始期及其后10d左右再各喷施药剂1次为最佳防治适期300 g ai/hm^2的20%噻菌铜对芝麻青枯病的防治效果达71.11%和74.25%,增产率33.95%~36.73%。2017-2018年试验结果显示,20%噻菌铜(300 g ai/hm^2)、20%噻唑锌(300 g ai/hm^2)和3%中生菌素(22.5 g ai/hm^2)对青枯病的防效范围为70.02%~75.23%;芝麻增产范围为32.14%~35.63%,3种药剂的防效和增产幅度差异均不显著。展开更多
文摘This paper bursts the bondage of conventional no-burn thought, presents an optimum strategy permitting burn appear in grinding roughing stage, but the burning layer can be summed on the following finishing stage. On the base of the basic grinding models, the objective function and constrained functions for the multiparameter optimum grinding models had been built in this paper. By the computer simulation, the nonlinear optimum grinding control parameters had been obtained, and the truth grinding process had been controlled by these parameters. The results of simulation and the experiments proved the exactitude of the optimum models and the feasibility of the optimum strategy. This paper had also created the precondition for the grinding automation, virtual grinding and intelligent grinding system for cylindrical grinding process.
基金Projects(2012CB619505,2010CB731703)supported by the National Basic Research Program of ChinaProject(CX2013B065)supported by Hunan Provincial Innovation Foundation for Postgraduate,China+1 种基金Project(51405520)supported by the National Natural Science Foundation of ChinaProject(zzyjkt2013-06B)supported by the State Key Laboratory of High Performance Complex Manufacturing(Central South University),China
文摘In order to study the bending behavior of aluminum alloy 7050 thick plate during snake hot rolling, several coupled thermo-mechanical finite element(FE) models were established. Effects of different initial thicknesses, pass reductions, speed ratios and offset distances on the bending value of the plate were analyzed. ‘Quasi smooth plate' and optimum offset distance were defined and quasi smooth plate could be acquired by adjusting offset distance, and then bending control equation was fitted. The results show that bending value of the plate as well as the extent of the increase grows with the increase of pass reduction and decrease of initial thickness; the bending value firstly increases and then keeps steady with the ascending speed ratio; the bending value can be reduced by enlarging the offset distance. The optimum offset distance varies for different rolling parameters and it is augmented with the increase of pass reduction and speed ratio and the decrease of initial thickness. A proper offset distance for different rolling parameters can be calculated by the bending control equation and this equation can be a guidance to acquire a quasi smooth plate. The FEM results agree well with experimental results.
文摘An optimum PN guidance law for maneuvering target is developed using optimal control theory.By estimating the target position and setting the cost function,the guidance law can be deduced even without knowing the missile lateral acceleration.Since the quadratic cost function can make a compromise between the miss distance and the control constraint,the optimum guidance law obtained is more general.Also,introduced line of sight rate as the input,a practical form of this guidance law is derived.The simulation results show the effectiveness of the guidance laws.
文摘作为网络传输控制机制的核心,拥塞控制关注如何在异构网络环境中最优化特定传输性能目标。已有拥塞控制机制忽略了不同应用的性能偏好在吞吐量-时延两个维度上的帕累托最优前沿(Pareto optimal frontier,POF)分布,难以满足差异化应用的性能需求。针对上述问题,本文提出了一种面向应用性能偏好的帕累托最优拥塞控制机制pBBR(ParetooptimalBBR),结合离线网络场景学习和在线控制参数优化的思想,最大程度满足应用的差异化性能偏好。实验结果表明,pBBR能够在一个采集-识别周期内判断出网络场景的切换,从而快速选择当前网络场景的最优控制参数。每个网络场景下,pBBR都能够最大化满足不同的应用性能偏好:针对吞吐量敏感业务,pBBR可以达到Cubic(吞吐优先)的97%,且时延只有Cubic的52%;针对时延敏感业务,pBBR的时延可以达到Sprout(时延优先)的95%,同时吞吐量损失只有1%。此外,多参数优化可进一步提升pBBR性能,例如在高铁长期演进技术(long term evolution,LTE)通信场景下,单参数pBBR的吞吐量、时延分别是Cubic的94%和99%,而三参数pBBR则分别提升到Cubic的101%和93%(优于Cubic)。
文摘青枯雷尔氏菌(Ralstonia solanacearum)引起芝麻青枯病,制约我国南方芝麻生产。为制定精准的药剂防治技术,在江西省南昌县连续4年建立病害观察圃,研究病害发生特点,选择芝麻连作田块,研究用药适期和筛选药剂。结果发现,芝麻青枯病多于现蕾期前后开始发病,初花期病情指数增长率均最为急剧;芝麻定苗时进行药剂喷淋护根,初花始期及其后10d左右再各喷施药剂1次为最佳防治适期300 g ai/hm^2的20%噻菌铜对芝麻青枯病的防治效果达71.11%和74.25%,增产率33.95%~36.73%。2017-2018年试验结果显示,20%噻菌铜(300 g ai/hm^2)、20%噻唑锌(300 g ai/hm^2)和3%中生菌素(22.5 g ai/hm^2)对青枯病的防效范围为70.02%~75.23%;芝麻增产范围为32.14%~35.63%,3种药剂的防效和增产幅度差异均不显著。
