Energy-Efficient Optimal Guaranteed Cost Intermittent-Switch Control of a Direct Expansion Air Conditioning System

To improve the energy efficiency of a direct expansion air conditioning(DX A/C) system while guaranteeing occupancy comfort, a hierarchical controller for a DX A/C system with uncertain parameters is proposed. The control strategy consists of an open loop optimization controller and a closed-loop guaranteed cost periodically intermittent-switch controller(GCPISC). The error dynamics system of the closed-loop control is modelled based on the GCPISC principle. The difference,compared to the previous DX A/C system control methods, is that the controller designed in this paper performs control at discrete times. For the ease of designing the controller, a series of matrix inequalities are derived to be the sufficient conditions of the lower-layer closed-loop GCPISC controller. In this way, the DX A/C system output is derived to follow the optimal references obtained through the upper-layer open loop controller in exponential time, and the energy efficiency of the system is improved. Moreover, a static optimization problem is addressed for obtaining an optimal GCPISC law to ensure a minimum upper bound on the DX A/C system performance considering energy efficiency and output tracking error. The advantages of the designed hierarchical controller for a DX A/C system with uncertain parameters are demonstrated through some simulation results.

Controllability of an underactuated spacecraft with one thruster under disturbance

For an underactuated spacecraft using only one thruster, the attitude controllability with respect to the or- bit frame is studied in the presence of periodical oscillation disturbance, which provides a preconditional guide on de- signing control law for underactuated attitude control sys- tem. Firstly, attitude dynamic model was established for an underactuated spacecraft, and attitude motion was described using the special orthogonal group （SO （3））. Secondly, Liou- ville theorem was used to confirm that the flow generated by the drift vector of the underactuated attitude control system is volume-preserving. Furthermore, according to Poincar6＇s re- currence theorem, we draw conclusions that this drift field is weakly positively poisson stable （WPPS）. Thirdly, the suffi- cient and necessary condition of controllability was obtained on the basis of lie algebra rank condition （LARC）. Finally, the controllable conditions were analyzed and simulated in different cases of inertia matrix with the installed position of thruster.

Design of BLDCM Driving and Control System for Motorized Treadmill

To satisfy the requirement of developing a new generation of motorized treadmill for a famous domestic manufacturer, a brushless DC motor （BLDCM） driving and control system for motorized treadmill is developed. High integration and reliability of this system are ensured under the condition that intelligent power module （IPM） is used and the protection module is included. Periodic current control method is applied to reduce the average current flowing through the armature winding of the motor when the treadmill is required to start with low speed while large load is added. Piecewise proportion-integration-differentiation （PID） control algorithm is applied to solve the problem of speed fluctuation when impulse load is added. The motorized treadmill of a new generation with the driving and control system has the advantages of high reliability, good speed stability, wide timing scope, low cost, and long life-span. And it is very promising for practical applications.

Atmospheric Pollution Control Effect of Key Cities in Inner Mongolia in 2014

APEC conference was held in Beijing during November 3- 12,2014. Hohhot City and Baotou City fall into the peripheral key air pollution control cities in the ＂ Beijing- Tianjin- Hebei＂ region. Inner Mongolia government adopted powerful pollution control measures in the period of the conference. According to pollutant concentration data and meteorological data etc. in the course of the event and the same period of last year,the atmospheric pollution variations and control effect were discussed in this study. The results showed that during October 1- 25,2014,there were 16 days with air pollution in Hohhot City and 15 days with air pollution in Baotou City,respectively increasing by 8% and 34% compared with the same period of 2013,and the concentration of particulate matter was also higher than that of last year. During October 22- 24,2014,Hohhot and Baotou cities were polluted persistently. The variation features of hourly concentration of main pollutants PM（10） and PM2. 5were similar to those in the same period of 2013. That is,the pollutant concentration reached the maximum from 21：00 to 23：00,and the minimum appeared from 15： 00 to 19： 00 in the next day. In the course of the event,the concentration of particulate matter in the two cities stared to reduce greatly on October 26. From October 26 to November 13,there were no days with air pollution in Hohhot City,decreasing by 100% compared with the same period of 2013; there were five days with air pollution in Baotou City,and the numbers of days with slight,moderate and severe pollution reduced by 37%,100% and67% respectively compared with the same period of last year. The persistent air pollution from October 22 to the first 10 days of November was related to unfavorable meteorological conditions,and the meteorological condition in the same period of 2014 was even worse. In the course of the event,the Inner Mongolia Government adopted air pollution control measures around October 25 and began to adopt some powerful pollution control measures on November 1. As a result,air pollution in key cities has been controlled effectively. This event showed that urban atmospheric pollution problem can be resolved,and we should take an optimistic attitude towards this matter.

What can the changes in shield resistance tell us during the period of shearer's cutting and neighboring shields' advance?

In order to determine the influence of shearer's cutting and neighboring shields' advance on the support resistance variation, leg pressure data of all 235 shields in the panel LW61 of Cumberland coal mine were analyzed. The results show that the relationship between the leg pressure increment and the distance from shield to front drum of shearer is a quadratic function and that the higher leg pressure increment before shield advance tends to be related to adverse roof conditions. In addition, the three proposed leg pressure increment-related parameters and the three traditional parameters(time-weighted average pressure, setting pressure, and final pressure) of approximately 32000 shield supporting cycles were calculated by a self-developed software package to analyze the correlation between them. The results show that there is a powerful connection between them, and that the three proposed leg pressure increment-related parameters could be used as the indexes to evaluate the interaction between shields and the roof, and to identify the periodic weighting.

Exponential synchronization for neural networks with mixed time-varying delays via periodically intermittent control

This paper deals with exponential synchronization for a class of neural networks with mixed time-varying delays via periodically intermittent control. Some novel and effective exponential synchronization criteria are derived by constructing Lyapunov functional and applying some analysis techniques. These results presented in this paper generalize and improve many known results. Finally, this paper presents an illustrative example and uses the simulated results to show the feasibility and effectiveness of the proposed scheme.

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.

Bi-normalized response spectra and seismic intensity in Bucharest for 1986 and 1990 Vrancea seismic events

The Vrancea subcrustal earthquakes of August 30,1986 and May 30,1990 are the two most recent seismic events that have occurred in Romania with moment magnitudes M W ≥ 6.9.The spectral analysis of the strong ground motions recorded in Bucharest reveals that despite small differences in magnitude between the 1986 and 1990 earthquakes,their frequency contents are very different,sometimes even opposing.The main focus of this study is to conduct a comparative analysis of the response spectra in terms of the bi-normalized response spectra(BNRS) proposed by Xu and Xie(2004 and 2007) for strong ground motions recorded in Bucharest during these two seismic events.The mean absolute acceleration and relative velocity response spectra for the two earthquakes are discussed and compared.Furthermore,the mean bi-normalized absolute acceleration and normalized relative velocity response spectra with respect to the control period T C are computed for the ground motions recorded in Bucharest in 1986 and 1990.The predominant period T P is also used in this study for the normalization of the spectral period axis.Subsequently,the methodology proposed by Martinez-Perreira and Bommer(1998) is applied in order to estimate the seismic intensity of the two events.The results are discussed and several conclusions regarding the possibility of using the bi-normalized response spectra(BNRS) are given.

Prevention of wing rock motion for lightly damped aircraft in lateral-directional dynamics

Based on the Ricatti technique, the methodology for preventing the limit cycle accomplished by adding a control function to the original equation of wing rock motion is presented in this paper. To analyze the state variables of the system, the complete set of nonlinear equations of motion including an effective linear control function was solved for A-4D and Mig-21 Aircraft. The roll angle responding to the linear control function for both models was estimated when the systems were tested under different damping ratios. The numerical re- suits show that a linear control function including both the roll attitude and the roll rate is sufficient to suppress the wing rock motion with an acceptable error in desired time. A good agreement between the numerical results and the published work is obtained for the limit cycle oscillation existence at different damping ratios.

A modified similitude analysis method for the electro-mechanical performances of a parallel manipulator to solve the control period mismatch problem

Due to the discrete feature and performance limitation of the numerical controller,the control period sometimes cannot meet the constraints of the scaled model in similitude analysis,which brings the control period mismatch problem.The traditional similitude analysis methods are not able to solve this problem since the controller is treated as continuous system in these methods.This paper proposes a modified similitude analysis method to solve the control period mismatch problem,and the electro-mechanical performances of a 2-DOF parallel manipulator is predicted.Based on the model of dynamic and control system,most of the similitude laws are derived by taking the controller as continuous system.Then the transfer function of the controller in discrete form is established,and the similitude law related to control period is derived to figure out the cause of mismatch problem.The modified method,named long period equivalent,is proposed to solve the mismatch problem by using the least square method and superposition principles.Finally,the scaled model of the parallel manipulator is determined based on the modified similitude analysis method.

Scaled Bipartite Consensus Controller Design for Second-Order Multi-Agent Systems with Mixed Time-Delays

The scaled bipartite consensus of second-order multi-agent systems is investigated in this paper.The internal delay and distributed delay are also considered in the dynamic model of each agent,in which the delays can be time-varying and large.The communication topology among agents is assumed to be directed and structurally balanced.On one hand,in order to guarantee scaled bipartite consensus of second-order multi-agent systems,an adaptive periodically intermittent control protocol is applied.On the other hand,some consensus criteria in the form of matrix inequalities are obtained by using Jensen inequality,Lyapunov stability theory and graph theory.Finally,a numerical simulation example is given to demonstrate the feasibility of theoretical results.

Experimental investigation of control updating period monitoring in industrial PLC-based fast MPC： Application to the constrained control of a cryogenic refrigerator

In this paper, a complete industrial validation of a recently published scheme for on-line adaptation of the control updating period in model predictive control is proposed. The industrial process that serves in the validation is a cryogenic refrigerator that is used to cool the supra-conductors involved in particle accelerators or experimental nuclear reactors. Two recently predicted features are validated： the first states that it is sometimes better to use less efficient （per iteration） optimizer if the lack of efficiency is overmcompensated by an increase in the updating control frequency. The second is that for a given solver, it is worth monitoring the control updating period based on the on-line measured behavior of the cost function.

Simultaneous pole-placement/stabilization of pairs of linear time-invariant plants using a continuous-time periodic controller

Given a pair of single input single output （SISO）, linear time-invariant （LTI）, and strictly proper plants of relative order r, this paper employs a continuous-time periodic controller to achieve 1） simultaneous pole-placement for r = 1 and 2） guaranteed simultaneous stabilization for r = 2, 3, and 4, which jobs LTI controllers cannot, in general, do. The controller also ensures insignificant output ripples. The analysis is based on averaging principle. The computational steps for controller synthesis are linear algebraic in nature. An example illustrates the design procedure.

Analysis and control of a non-smooth population model with impulsive effects

In this paper, a non-smooth population model with impulsive effects is proposed by combining discontinuity and non-smoothness. According to the qualitative theory of differential equations, the global analysis of the model is discussed. Using the theory of impulsive differential equations, the existence conditions of order one periodic solution are obtained. And the impulsive controllers are designed to make the pest populations stay at the refuge level. Some simulations are carried out to prove the results.

Optimal control for spatial-temporal distributed nonlinear autoregressive with exogenous inputs correlation model of steel rolling reheating furnace: a coordinated time-sharing control approach

Accurate control of slab temperature and heating rate is an important significance to improve product performance and reduce carbon emissions for steel rolling reheating furnace(SRRF).Firstly,a spatial temporal distributed-nonlinear autoregressive with exogenous inputs correlation model(STD-NARXCM)to spatial temporal distributed-autoregressive with exogenous inputs correlation model(STD-ARXCM)in working point is established.Secondly,a new coordinated time-sharing control architecture in different time periods is proposed,which is along the length of the SRRF to improve the control performance.Thirdly,a hybrid control algorithm of expert-fuzzy is proposed to improve the dynamic of the temperature and the heating rate during time period 0 to t_(1).A hybrid control algorithm of expert-fuzzy-PID is proposed to enhance the control accuracy and the heating rate during time period t_(1) to t_(2).A hybrid control algorithm of expert-active disturbance rejection control(ADRC)is proposed to boost the anti-interference and the heating rate during time period t_(2) to t_(3).Finally,the experimental results show that the coordinated time-sharing algorithm can meet the process requirements,the maximum deviation of temperature value is 8-13.5℃.

Probe frequency- and field intensity-sensitive coherent control effects in an EIT-based periodic layered medium

A periodic layered medium, with unit cells consisting of a dielectric and an electromagnetically-induced transparency （EIT）-based atomic vapor, is designed for light propagation manipulation. Considering that a destructive quantum interference relevant to a two-photon resonance emerges in EIT-based atoms interacting with both control and probe fields, an EIT-based periodic layered medium exhibits a flexible frequency-sensitive optical response, where a very small variation in the probe frequency can lead to a drastic variation in reflectance and transmittance. The present EIT-based periodic layered structure can result in controllable optical processes that depend sensitively on the external control field. The tunable and sensitive optical response induced by the quantum interference of a multi-level atomic system can be applied in the fabrication of new photonic and quantum optical devices. This material will also open a good perspective for the application of such designs in several new fields, including photonic microcircuits or integrated optical circuits.

3D image reconstruction with controllable spatial filtering based on correlation of multiple periodic functions in computational integral imaging

We propose a novel method of slice image reconstruction with controllable spatial filtering by using the correlation of periodic delta-function arrays （PDFAs） with elemental images in computational integral imaging. The multiple PDFAs, whose spatial periods correspond to object＇s depths with the elemental image array （EIA）, can generate a set of spatially filtered EIAs for multiple object depths compared with the conventional method for the depth of a single object. We analyze a controllable spatial filtering effect by the proposed method. To show the feasibility of the proposed method, we carry out preliminary experiments for multiple objects and present the results.

MINIMUM PERIOD CONTROL PROBLEM FOR INFINITE DIMENSIONAL SYSTEM

In order to solve the so-called minimum period control problem for a class of abstract evolutionary systems, the authors study an infinite dimensional time optimal control problem with mixed type target set. To the latter problem complete results are established, which then are applied to the former to derive the desirable answer.