A force control high-order single-step-β method (HSM) for substructure pseudo-dynamic testing

This paper proposes a new technique which introduces the high-order single-step-β method(HSM)into the experimental study on the substructure pseudo-dynamic testing(SPDT).The technique is based on the proposed concept of equivalent shear stiffness which can meet the requirement of the HSM algorithm.A study is done to theoretically validate the technique by the numerical analysis of two-storey shear building structure,in comparison of the proposed substructure pseudo-dynamic testing algorithm with the central difference method(CDM).Then,a full-scale SPDT model,the three-storey frame-supported reinforced concrete short-limb masonry shear wall structure,is designed and tested to simulate the seismic response of the corresponding six-storey structure and verify the proposed force control HSM technique.Meanwhile,the techniques of both stiffness correction and force control are suggested to control algorithmic error,control error and measurement error.The results indicate that the force control HSM can be used in the full-scale multi-degree-of-freedom(MDOF)substructure pseudo-dynamic testing before descent segment of structure restoring force properties.

Effect of direction error on the miss distance of rolling missiles with x-rudder

Based on the analysis of periodic equivalent control force of rolling missiles with x-rudder, the guidance loop model with direction error is established and the relationship between direction error and miss distance is analyzed. Results show that the miss distance is zero or a constant or infinite, and it is always zero when the real parts of system matrix eigenvalues decided by direction error are both positive values in an ideal system, in which all the lags are neglected. However, the miss distance gradually increases with the increase of the direction error and its variation is small when direction error is not more than 5° in the system, in which seeker lag and missile body lag are considered.

Synthesis identification analysis for closed loop system

The existing theories for closed loop identification with the linear feedback controller are very mature.To apply the existed theories directly in the control field,we propose a new idea about replacing the original unknown and nonlinear feedback controller with one approximated linear controller,while guaranteeing the equivalent property for the obtained closed loop system.Based on some statistical correlation functions,one condition is derived to show the equivalent property between the approximated linear controller and the original nonlinear controller.The detailed explicit form,corresponding to the approximated linear controller,is also constructed.Furthermore,to give a complete analysis for closed loop identification,the cost function is rewritten as one extended expression,being convenient to understand.Then spectral estimation is introduced to identify the unknown plant in the closed loop system.Finally,the proposed theories are verified by one simulation example.

电子包装秤自学习智能控制系统

提出了电子包装秤自学习智能控制算法，可据系统特征状态及控制目标集的要求，判断控制效果，按最小当量原理，从控制过程中“学习”控制经验，修改控制规则，逐步趋近最优控制．现场运行证明：与常规定值控制算法相比，该系统有较强的抗干扰和自适应能力．

Analysis and Design of Switching Surface for Nonlinear Variable Structure Control Systems

One of the main problems in variable structure control systems is finding the switching surface on which the controlled plant has a desired specific behaviour.This paper presents a new method for finding switching surfaces of nonlinear variable structure systems. Using this method, the designer first presents a system with the desired properties, then finds the switching function σ(x) such that the switching surface S∶={x∈R n|σ(x)=0} is coincident with the sliding motion in the given system. This method is applied to the design of the variable structure controller in a power system and the highest transient stability limitations are attained.

Nonlinear VSC Technique for Power System Integrate Controllers

This paper studies the nonlinear variable structure control (VSC) technique for designing power system integrate control systems which include an excitation controller and fast valve controller.A new method is applied to find nonlinear switching surface in deriving the control strategy.The responses to various large perturbation are simulated.The simuulation results show that the nonlinear VSC technique for integrated control systems can considerably improve the transient stabilization limitation of power systems and improve the dynamic properties of the generators.

NEW DELAY-DEPENDENT STABILITY CRITERIA AND ROBUST CONTROL OF NONLINEAR TIME-DELAY SYSTEMS

This paper investigates the stability analysis and H_∞ control for a class of nonlinear timedelay systems,and proposes a number of new results.Firstly,an equivalent form is given for this class of systems by means of coordinate transformation and orthogonal decomposition of vector fields.Then,based on the equivalent form,some delay-dependent results are derived for the stability analysis of the systems by constructing a novel Lyapunov functional.Thirdly,the authors use the equivalent form and the obtained stability results to investigate the H_∞ control problem for a class of nonhnear time-delay control systems,and present a control design procedure.Finally,an illustrative example is given to show the effectiveness of the results obtained in this paper.It is shown that the main results of this paper are easier to check than some existing ones,and have less conservatism.

Structural Properties in a Hub-to-Hub Network Revenue Management Problem

In this paper,the structural properties of revenue management in a hubto-hub airline network is studied.Using a reformulated network flow version of the problem,it is shown that the optimal value has supermodularity,submodularity,and Lconcavity in the network’s capacities dimensions.It is thus deduced that the certainty equivalent control thresholds used in the revenue management problem have monotone properties.These structural properties add important managerial insights into the network revenue management system.