调车作业量发生规律研究及选编模型优化

用数学模型表达调车作业过程次数、牵推钩数和连挂钩数等调车作业量的发生规律,并界定出其最优值。统筹对口调车法使连挂钩数达到最优,但牵推钩数较多,对其算法进行优化,可减少发生的牵推钩数,即实现减牵优化。消逆法使作业过程次数及牵推钩数达到最优,但连挂钩数较多,对其算法进行优化,可减少发生的连挂钩数,即实现减挂优化。溜放钩数的发生规律复杂且有随机性,尚不能用数学模型表达之,未能界定出其最优值,但确定出溜放钩数与用线数及作业过程次数的趋势性相关关系。归纳出利用两类可调元实现“减溜”的优化方法。针对调车作业优化的多指标性,提出的优化原则是,在作业过程次数和牵推钩数最优的前提下谋求减挂优化和减溜优化。指出统筹对口调车法中,由真逆组号数界限值所组成的菲波纳契数列,对其消逆速度的体现,以及消逆速度随真逆组号数的变化而同向变化的规律。

对口法的“减牵”优化研究

以对口法的"减牵"优化为目标,引入“入线步长”的概念,在分析确定其递变规律的基础上,指出可编顺组号数界限值遵循“入线步长”变化规律而形成菲波纳契数列的实质;通过研究“固定空元位”的合理取定方法,明确“取空区”的构成,发现其数量变化规律及该规律与入线步长变化规律的异同;基于上述研究,提出构建“减牵”入线结构、使对口法减少作业过程次数的优化方法,确定出可编顺组号数界限值新的分布状态,体现调车作业量与可编顺组号数界限值之间更为准确的对应关系。通过分析在不同作业过程实现“减牵”而出现的作业特点,确定出相对有利的“减牵”优化环节,从而减少入线结构备选方案,使优化进程加快。深化研究后,进一步提出“双减牵”优化的方法及其采用条件,使优化达到更高水平。用实例描述本研究给出的各优化过程,验证了优化结果。指出对口法和消逆法这两种主要的入线算法,在一定条件下经优化改进后而发生的趋同化现象。

ROBUST STABILIZATING FOR A OLASS OF UNOERTAIN NONLINEAR INTEROONNECTED SYSTEMS USING VARIABLE STRUCTURE CONTROL

The robust stabilizating control problem for a class of uncertain nonlinear large-scale systems is discussed. Based on the theory of both input/output (I/O) linearization and decentralized variable structure control (VSC),two-level and decentralized variable structure control laws for this kind of systems are presented respectively,which achieve asymptotically stabilization despite the uncertainties and disturbances. At last,sirnulation of the disturbed two-pendulum system is given to illustrate the feasibility of proposed technique.

A Position-Based Handoff Scheme in WAVE Systems

IEEE 802.11p has been proposed to extend the application of IEEE 802.11 to Wireless Access fast fading Vehicular Environments (WAVE).Due to the high velocities of vehicles and thus the inconstant topology of networks,it is extremely difficult to maintain communications without handoff in an Internet of Vehicles (IoV).Hence,fast handoff from one roadside unit (RSU) to another is necessary.Although some solutions have been given in IEEE 802.11r and 802.11f standards,the handoff latency is still as high as about 50 ms when adopting them.To address this issue in WAVE systems,a novel position-based handoff (PHO) scheme is proposed in this paper.In PHO scheme,the triggering of the handoff is accomplished by the location information of a vehicle instead of the power level of the received signal.Both the handoff process and latency of PHO scheme are analyzed.Finally,to verify the analytical results,simulations were conducted to date the effectiveness of the proposed PHO scheme.

Sliding mode identifier for parameter uncertain nonlinear dynamic systems with nonlinear input

This paper presents a sliding mode (SM) based identifier to deal with the parameter identification problem for a class of parameter uncertain nonlinear dynamic systems with input nonlinearity. A sliding mode controller (SMC) is used to ensure the global reaching condition of the sliding mode for the nonlinear system; an identifier is designed to identify the uncertain parameter of the nonlinear system. A numerical example is studied to show the feasibility of the SM controller and the asymptotical convergence of the identifier.

Structural analysis of [Bmim]_2CuCl_4 ionic liquids in the presence of water and ethanol by XAFS technique

The structure of [Bmim]2CuCl4 ionic liquids （Bmim： 1-butyl-3-methylimidazolium） with different ratios of H2O and C2H5OH was investigated using X-ray absorption fine structure （XAFS） technique. In this study, XAFS was employed to directly probe the conformational variations of copper ions in [Bmim]2CuCl4 with the addition of either water or ethanol. XAFS analysis confirmed that the structure of ionic liquids gradually transformed from tetrahedral to octahedral configuration with the increase in ratio of H2O. Our results also showed that water molecules coordinated with the copper ions of [Bmim]2CuCl4, leading to the conformational change in ionic liquids. However, the XAFS spectra of [Bmim]zCuCIa/C2H5OH indicated no coordination of anhydrous ethanol with the copper ions of [Bmim]2CuC14. The structure of [Bmim]2CuCl4 ionic liquids is maintained as the tetrahedral configuration in presence of ethanol. Therefore, anhydrous ethanol causes little variation in the structure of ionic liquids and it is a good solvent for the dilution of ionic liquids.

Derivation and analysis on the analytical structure of interval type-2 fuzzy controller with two nonlinear fuzzy sets for each input variable

Type-2 fuzzy controllers have been mostly viewed as black-box function generators. Revealing the analytical structure of any type-2 fuzzy controller is important as it will deepen our understanding of how and why a type-2 fuzzy controller functions and lay a foundation for more rigorous system analysis and design. In this study, we derive and analyze the analytical structure of an interval type-2 fuzzy controller that uses the following identical elements: two nonlinear interval type-2 input fuzzy sets for each variable, four interval type-2 singleton output fuzzy sets, a Zadeh AND operator, and the Karnik-Mendel type reducer. Through dividing the input space of the interval type-2 fuzzy controller into 15 partitions, the input-output relationship for each local region is derived. Our derivation shows explicitly that the controller is approximately equivalent to a nonlinear proportional integral or proportional differential controller with variable gains. Furthermore, by comparing with the analytical structure of its type-1 counterpart, potential advantages of the interval type-2 fuzzy controller are analyzed. Finally, the reliability of the analysis results and the effectiveness of the interval type-2 fuzzy controller are verified by a simulation and an experiment.