Feedback control scheme of traffic jams based on the coupled map car-following model

Based on the pioneering work of Konishi et al. [Phys. Rev. E （1999） 60 4000], a new feedback control scheme is presented to suppress traffic jams based on the coupled map car-following model under the open boundary condition. The effect of the safe headway on the traffic system is considered. According to the control theory, the condition under which traffic jams can be suppressed is analyzed. The results are compared with the previous results concerning congestion control. The simulations show that the suppression performance of our scheme on traffic jams is better than those of the previous schemes, although all the schemes can suppress traffic jams. The simulation results are consistent with theoretical analyses.

Design of process and control scheme for cyclohexanol production from cyclohexene using reactive distillation

Cyclohexanol is a commonly used organic compound.Currently,the most promising industrial process for synthesizing cyclohexanol,by cyclohexene hydration,suffers from a low conversion rate and difficult separation.In this paper,a three-column process for catalytic distillation applicable in the hydration of cyclohexene to cyclohexanol was established to solve these.Simulation with Aspen Plus shows that the process has good advantages,the conversion of cyclohexene reached 99.3%,and the product purity was>99.2%.The stable operation of the distillation system requires a good control scheme.The design of the control scheme is very important.However,at present,the reactive distillation process for cyclohexene hydration is under investigation experimentally and by steady-state simulation.Therefore,three different plant-wide control schemes were established(CS1,CS2,CS3) and the position of temperature sensitive stage was selected by using sensitivity analysis method and singular value decomposition method.The Tyreus-Luyben empirical tuning method was used to tune the controller parameters.Finally,Aspen Dynamics simulation software was used to evaluate the performance of the three control schemes.By introducing ΔF±20% and χ_(ENE)±5%,comparison the changes in product purity and yield of the three different control schemes.By comparison,we can see that the control scheme CS3 has the best performance.

CONTROL SCHEMES FOR CMAC NEURAL NETWORK-BASED VISUAL SERVOING

In IBVS (image based visual servoing), the error signal in image space should be transformed into the control signal in the input space quickly. To avoid the iterative adjustment and complicated inverse solution of image Jacobian, CMAC (cerebellar model articulation controller) neural network is inserted into visual servo control loop to implement the nonlinear mapping. Two control schemes are used. Simulation results on two schemes are provided, which show a better tracking precision and stability can be achieved using scheme 2.

Control schemes for synchronizing two subnetworks with weak couplings

In this paper, we propose a well-designed network model with a parameter and study full and partial synchronization of the network model based on the stability analysis. The network model is composed of a star-coupled subnetwork and a globally coupled subnetwork. By analyzing the special coupling configuration, three control schemes are obtained for synchronizing the network model. Further analysis indicates that even if the inner couplings in each subnetwork are very weak, two of the control schemes are still valid. In particular, if the outer coupling weight parameter 0 is larger than （n2 - 2n）/4, or the subnetwork size n is larger than 02, the two subnetworks with weak inner couplings can achieve synchronization. In addition, the synchronizability is independent of the network size in case of 0 〈 0 〈 n/（n ＋ 1 ）. Finally, we carry out some numerical simulations to confirm the validity of the obtained control schemes. It is worth noting that the main idea of this paper also applies to any network consisting of a dense subnetwork and a sparse network.

Application Strategy of PLC Technology in Energy-Saving Control of Tunnel Lighting

In this study,we investigated on the application of planar lightwave circuit(PLC)technology in energy-saving control of tunnel lighting.The application status of PLC in the field of energy saving followed by the necessity of energy saving in tunnel lighting was analyzed.Finally,the application of PLC in tunnel lighting energy-saving control around the three dimensions of system overall architecture design,control scheme,and program control process was investigated.The results showed that the system meets the requirements of control effect,robustness,and visual effect after trial operation,and is suitable for practical applications.

Direct and Indirect Gradient Control for Static Optimisation

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.

Modeling and Control of Head of the Underwater Snake-like Robot Swimming

In order to solve oscillation of head of the underwater snake-like robot,the Central Pattern Generator( CPG)-based control scheme with head-controller was presented. The Kane dynamic model was constructed to be processed with a commercial package MotionGenesis Kane 5. 3,to which the proposed control scheme was applied. The relation between CPG parameters and orientation offset of head was investigated. The target orientation of head-controller was calculated through a convenient method. The advantage of this control scheme is that the head of the underwater snake-like robot remains in the forward direction during swimming. To prove the feasibility of the proposed methodology,two basic motion patterns,swimming along the straight line and swimming along the curved path,had been implemented in our simulation platform. The results showed that the simulation platform can imitate the swimming of the underwater snake-like robot and the head of the underwater snake-like robot remains in a fixed orientation directed towards the target. The oscillation of head's orientation is inhibited effectively.

A Lyapunov-based three-axis attitude intelligent control approach for unmanned aerial vehicle

A novel Lyapunov-based three-axis attitude intelligent control approach via allocation scheme is considered in the proposed research to deal with kinematics and dynamics regarding the unmanned aerial vehicle systems.There is a consensus among experts of this field that the new outcomes in the present complicated systems modeling and control are highly appreciated with respect to state-of-the-art.The control scheme presented here is organized in line with a new integration of the linear-nonlinear control approaches,as long as the angular velocities in the three axes of the system are accurately dealt with in the inner closed loop control.And the corresponding rotation angles are dealt with in the outer closed loop control.It should be noted that the linear control in the present outer loop is first designed through proportional based linear quadratic regulator(PD based LQR) approach under optimum coefficients,while the nonlinear control in the corresponding inner loop is then realized through Lyapunov-based approach in the presence of uncertainties and disturbances.In order to complete the inner closed loop control,there is a pulse-width pulse-frequency(PWPF) modulator to be able to handle on-off thrusters.Furthermore,the number of these on-off thrusters may be increased with respect to the investigated control efforts to provide the overall accurate performance of the system,where the control allocation scheme is realized in the proposed strategy.It may be shown that the dynamics and kinematics of the unmanned aerial vehicle systems have to be investigated through the quaternion matrix and its corresponding vector to avoid presenting singularity of the results.At the end,the investigated outcomes are presented in comparison with a number of potential benchmarks to verify the approach performance.

Enhancement of Distributed Generation by Using Custom Power Device

Wind energy （WE） has become immensely popular for distributed generation （DG）. This case presents the monitoring, modeling, control, and analysis of the two-level three-phase WE based DG system where the electric grid interfacing custom power device （CPD） is controlled to perform the smart exchanging of electric power as per the Indian grid code. WE is connected to DC link of CPD for the grid integration purpose. The CPD based distributed static compensator, i.e. the distributed static synchronous compensator （DSTATCOM）, is utilized for injecting the wind power to the point of common coupling （PCC） and also acts against the reactive power demand. The novel indirect current control scheme of DSTATCOM regulates the power import and export between the WE and the electric grid system. It also acts as a compensator and performs both the key features simultaneously. Hence, the penetration of additional generated WE power to the grid is increased by 20% to 25%. The burden of reactive power compensation from grid is reduced by DSTATCOM. The modeling and simulation are done in MATLAB. The results are validated and verified.

Synchronization of impulsively coupled complex networks

We investigate the synchronization of complex networks,which are impulsively coupled only at discrete instants.Based on the comparison theory of impulsive differential systems,a distributed impulsive control scheme is proposed for complex dynamical networks to achieve synchronization.The proposed scheme not only takes into account the influence of all nodes to network synchronization,which depends on the weight of each node in the network,but also provides us with a flexible method to select the synchronized state of the network.In addition,it is unnecessary for the impulsive coupling matrix to be symmetrical.Finally,the proposed control scheme is applied to a chaotic Lorenz network and Chua＇s circuit network.Numerical simulations are used to illustrate the validity of this control scheme.

Head Orientation Stability of Underwater Snake-Like Robot Swimming

In prior research,the orientation of head of the snake-like robot is changed according to the sinusoidal wave. To solve this problem,we propose Central Pattern Generator( CPG)-based control scheme with head-controller to stabilize the head of the underwater snake-like robot. The advantage of the CPG-based control scheme with head-controller is that the head of the underwater snake-like robot is direct to the target orientation during swimming. The relation between CPG parameters and orientation stability of head is discussed.The adaptation of the proposed method to environment changes is tested. The influences of CPG parameters and hydrodynamic forces on the orientation offset of head are investigated. The target orientation( the input of headcontroller) with an experimental optimization is calculated through a convenient method. To prove the feasibility of the proposed methodology,the different swimming modes have been implemented in our simulation platform.The results show that the oscillation of head's orientation is inhibited effectively,and the proposed method has strong adaptation to environment and CPG parameters changes.

Reliability Evaluation of Wind Power Converter Under Fault-tolerant Control Scheme with Quantification of Temperature and Humidity Effects

Wind power converter(WPC)is a key part of a wind power unit which delivers electric energy to power grid.Because of a large number of semiconductors,WPC has a high failure rate.This paper proposes a method to accurately evaluate the reliability of WPC,which is crucial for the design and maintenance of wind turbines.Firstly,the index of effective temperature(ET)is presented to quantify the effects of temperature and humidity on the semiconductor operation.A novel method is proposed to evaluate the lifetime and calculate the aging failure rates of the semiconductors considering the fluctuations of ET.Secondly,the failure mode and effect analysis(FMEA)of WPC is investigated based on the topology and control scheme.The conventional two-state reliability model of the WPC is extended to the multi-state reliability model where the partial working state under the fault-tolerant control scheme is allowed.Finally,a reliability evaluation framework is established to calculate the parameters of the WPC reliability model considering the variable failure rates and repair activities of semiconductors.Case studies are designed to verfify the proposed method using a practical wind turbine.

Optimal Initialization and Starting Approach of Synchronous Condenser Integrated Power Grid

Synchronous condensers(SCs)are generally used at the receiving-end stations of ultra-high-voltage direct current(UHVDC)transmission systems due to their strong reactive power support and flexible regulation of reactive power according to the interconnected grids operating conditions.In this paper,different starting control schemes of a SC integrated power grid are investigated providing four main contributions:1)The principle of reactive power support of the SC on the interconnected power grid is analytically studied,providing the establishment of mathematical models.2)Four different starting control schemes are developed for the initialization and SC integration,i.e.in Scheme 1,a preset initial falling speed is directly utilized without initialization;in Scheme 2,a black start sequential control approach with a static frequency converter(SFC)is proposed;in Scheme 3,PI/PD/PID controllers are respectively applied for the excitation device at the speed-falling stage;in Scheme 4,a pre-insertion approach of an energy absorption component with R/L/RL is utilized to suppress the surges at the SC integration instant.3)The dynamic behaviors of four different starting schemes at specific operating stages are evaluated.4)The success rate of SC integration is analyzed to evaluate starting control performance.Performance of the SC interconnected system with four different starting control schemes is evaluated in the timedomain simulation environment PSCAD/EMTDC^(TM).The results prove the superiority of the proposed starting control approach in Scheme 4.

Decentralized Primary Frequency Regulation for Hybrid Multi-terminal Direct Current Power Systems Considering Multi-source Enhancement

Hybrid multi-terminal direct current(MTDC)transmission technology has been a research focus,and primary frequency regulation(FR)improvement in the receiving-end system is one of the problems to be solved.This paper presents a decentralized primary FR scheme for hybrid MTDC power systems considering multi-source enhancement to help suppress frequency disturbance in the receiving-end systems.All the converters only need local frequency or DC voltage signal input to respond to system disturbance without communication or a control center,i.e.,a decentralized control scheme.The proposed scheme can activate appropriate power sources to assist in FR in various system disturbance severities with fine-designed thresholds,ensuring sufficient utilization of each power source.To better balance FR performance and FR resource participation,an evaluation index is proposed and the parameter optimization problem is further conducted.Finally,the validity of the proposed scheme is verified by simulations in MATLAB/Simulink.

Gust response modeling and alleviation scheme design for an elastic aircraft

Time-domain approaches are presented for analysis of the dynamic response of aeroservoelastic systems to atmospheric gust excitations. The continuous and discrete gust inputs are defined in the time domain. The time-domain approach to continuous gust response uses a state-space formulation that requires the frequency-dependent aerodynamic coefficients to be approximated with the rational function of a Laplace variable. A hybrid method which combines the Fourier transform and time-domain approaches is used to calculate discrete gust response. The purpose of this approach is to obtain a time-domain state-space model without using rational function approximation of the gust columns. Three control schemes are designed for gust alleviation on an elastic aircraft, and three control surfaces are used: aileron, elevator and spoiler. The signals from the rate of pitch angle gyroscope or angle of attack sensor are sent to the elevator while the signals from accelerometers at the wing tip and center of gravity of the aircraft are sent to the aileron and spoiler, respectively. All the control laws are based on classical control theory. The results show that acceleration at the center of gravity of the aircraft and bending-moment at the wing-root section are mainly excited by rigid modes of the aircraft and the accelerations at the wing-tip are mainly excited by elastic modes of the aircraft. All the three control schemes can be used to alleviate the wing-root moments and the accelerations. The gust response can be alleviated using control scheme 3, in which the spoiler is used as a control surface, but the effects are not as good as those of control schemes 1 and 2.

Chaos Synchronization in the Belousov-Zhabotinsky Chemical Reaction by Adaptive Control Scheme

The adaptive synchronization scheme proposed by John and Amritkar was employed into the Belousov Zhabotinsky (BZ) 4 variable Montanator model system. By the parameter adjustment, chaos synchronization has been obtained. Through calculating the transient time, the optimal combination of the stiffness constant and damping constant was obtained. Furthermore, the relationships among the transient time, conditional Lyapunov exponents, the stiffness constant and damping constant were discussed. Also, the BZ system with the adaptive synchronization scheme might be used for the communication purposes.

Improvement on Spherical Symmetry in Two-Dimensional Cylindrical Coordinates for a Class of Control Volume Lagrangian Schemes

In[14],Maire developed a class of cell-centered Lagrangian schemes for solving Euler equations of compressible gas dynamics in cylindrical coordinates.These schemes use a node-based discretization of the numerical fluxes.The control volume version has several distinguished properties,including the conservation of mass,momentum and total energy and compatibility with the geometric conservation law(GCL).However it also has a limitation in that it cannot preserve spherical symmetry for one-dimensional spherical flow.An alternative is also given to use the first order area-weighted approach which can ensure spherical symmetry,at the price of sacrificing conservation of momentum.In this paper,we apply the methodology proposed in our recent work[8]to the first order control volume scheme of Maire in[14]to obtain the spherical symmetry property.The modified scheme can preserve one-dimensional spherical symmetry in a two-dimensional cylindrical geometry when computed on an equal-angle-zoned initial grid,andmeanwhile itmaintains its original good properties such as conservation and GCL.Several two-dimensional numerical examples in cylindrical coordinates are presented to demonstrate the good performance of the scheme in terms of symmetry,non-oscillation and robustness properties.

Admission Control Scheme for Handover Service in High-Speed Train Communication System

Admission control in high-speed train communication system is quite different from admission control in traditional cellular networks. Conventional admission control strategies cannot be directly applied to this special communication scenario. In this paper, the problem of admission control for handover service is investigated in high-speed train communication environment. An admission control scheme considering bit error rate(BER)and bandwidth borrowing strategy is proposed. On the basis of admission control decision rule taking BER into account, a part of bandwidth obtained by compressing variable rate service in the networks is provided for handover services. The admission control scheme can admit handover services as more as possible while it guarantees the lowest data rate of different services in the networks. Simulation results show that the proposed admission control scheme has a better performance than existing admission control schemes.

Optimized and coordinated model predictive control scheme for DFIGs with DC-based converter system

This paper proposes an optimized and coordinated model predictive control(MPC) scheme for doublyfed induction generators(DFIGs) with DC-based converter system to improve the efficiency and dynamic performance in DC grids. In this configuration, the stator and rotor of the DFIG are connected to the DC bus via voltage source converters, namely, a rotor side converter(RSC) and a stator side converter(SSC). Optimized trajectories for rotorflux and stator current are proposed to minimize Joule losses of the DFIG, which is particularly advantageous at low and moderate torque. The coordinated MPC scheme is applied to overcome the weaknesses of the field-oriented control technique in the rotor flux-oriented frame, which makes the rotor flux stable and the stator current track its reference closely and quickly. Lastly, simulations and experiments are carried out to validate the feasibility of the control scheme and to analyze the steady-state and dynamic performance of the DFIG.