ACTIVE STRUCTURAL ACOUSTIC CONTROL IN ENCLOSURE USING RADIATION MODES

The problem of active structural acoustic control in an enclosure using radiation mode is investigated. The response of the coupled enclosure is derived in terms of radiation modes. The potential energy in the enclosure can be decomposed into independent parts and the radiation modes contribute to potential energy independently. The control strategy for minimizing first G radiation modes with large radiation efficiency is proposed, and the optimal model of control forces is presented. Finally, a numerical simulation for minimizing sound transmission into a rectangular enclosure using the proposed method is conducted. Simulation results indicate that one control force can control one radiation mode and controlling the first four-order radiation modes with four control forces can achieve significant potential energy reduction at the low frequency range.

HPR1000： Advanced Pressurized Water Reactor with Active and Passive Safety

HPR1000 is an advanced nuclear power plant(NPP)with the significant feature of an active and passive safety design philosophy,developed by the China National Nuclear Corporation.On one hand,it is an evolutionary design based on proven technology of the existing pressurized water reactor NPP;on the other hand,it incorporates advanced design features including a 177-fuel-assembly core loaded with CF3 fuel assemblies,active and passive safety systems,comprehensive severe accident prevention and mitigation measures,enhanced protection against external events,and improved emergency response capability.Extensive verification experiments and tests have been performed for critical innovative improvements on passive systems,the reactor core,and the main equipment.The design of HPR1000fulfills the international utility requirements for advanced light water reactors and the latest nuclear safety requirements,and addresses the safety issues relevant to the Fukushima accident.Along with its outstanding safety and economy,HPR1000 provides an excellent and practicable solution for both domestic and international nuclear power markets.

Smart Material Based Complex Mode Active Control of Flexible Manipulators with Kinematic Redundancy

An active control methodology is presented for suppressing the vibratoryresponse of flexible redundant manipulators with bonded piezoceramic actuators and strain gagesensors. Firstly, the dynamic equation of the manipulator is decoupled by means of the complex modetheory and the state-space expression of the controlled system is developed. Secondly, a continuouslinear quadratic regulator (LQR) state feedback controller is designed based on the minimumprinciple. Thirdly, a full-order Luenberger state observer featuring an assigned degree of stabilityis determined via the duality between control and estimation. Finally, a numerical simulation iscarried out on a planar 3R flexible redundant manipulator. The simulation results reveal that thedynamic performance of the system is improved rapidly and significantly.

Fuzzy Sliding Mode Active Disturbance Rejection Control of an Autonomous Underwater Vehicle-Manipulator System

In this paper, a fuzzy sliding mode active disturbance rejection control(FSMADRC) scheme is proposed for an autonomous underwater vehicle-manipulator system(AUVMS) with a two-link and three-joint manipulator. First, the AUVMS is separated into nine subsystems, and the combined effects of dynamic uncertainties, hydrodynamic force, unknown disturbances, and nonlinear coupling terms on each subsystem are lumped into a single total disturbance. Next, a linear extended state observer(LESO) is presented to estimate the total disturbance. Then, a sliding mode active disturbance rejection control(SMADRC) scheme is proposed to enhance the robustness of the control system. The stability of the SMADRC and the estimation errors of the LESO are analyzed. Because it is difficult to simultaneously adjust several parameters for a LESO-based SMADRC scheme, a fuzzy logic control(FLC) scheme is used to formulate the FSMADRC to determine the appropriate parameters adaptively for practical applications. Finally, two AUVMS tasks are illustrated to test the trajectory tracking performance of the closed-loop system and its ability to reject and attenuate the total disturbance. The simulation results show that the proposed FSMADRC scheme achieves better performance and consume less energy than conventional PID and FLC techniques.

A B-spline active contour model based on finite element method

A B-spline active contour model based on finite element method is presented, into which the advantages of a B-spline active contour attributing to its fewer parameters and its smoothness is built accompanied with reduced computational complexity and better numerical stability resulted from the finite element method. In this model, a cubic B-spline segment is taken as an element, and the finite element method is adopted to solve the energy minimization problem of the B-spline active contour, thus to implement image segmentation. Experiment results verify that this method is efficient for B-spline active contour, which attains stable, accurate and faster convergence.

Semi-active Sliding Mode Control of Vehicle Suspension with Magneto-rheological Damper

The vehicle semi-active suspension with magneto-theological damper（MRD） has been a hot topic since this decade, in which the robust control synthesis considering load variation is a challenging task. In this paper, a new semi-active controller based upon the inverse model and sliding mode control （SMC） strategies is proposed for the quarter-vehicle suspension with the magneto-rheological （MR） damper, wherein an ideal skyhook suspension is employed as the control reference model and the vehicle sprung mass is considered as an uncertain parameter. According to the asymptotical stability of SMC, the dynamic errors between the plant and reference systems are used to derive the control damping force acquired by the MR quarter-vehicle suspension system. The proposed modified Bouc-wen hysteretic force-velocity （F-v） model and its inverse model of MR damper, as well as the proposed continuous modulation （CM） filtering algorithm without phase shift are employed to convert the control damping force into the direct drive current of the MR damper. Moreover, the proposed semi-active sliding mode controller （SSMC）-based MR quarter-vehicle suspension is systematically evaluated through comparing the time and frequency domain responses of the sprung and unsprung mass displacement accelerations, suspension travel and the tire dynamic force with those of the passive quarter-vehicle suspension, under three kinds of varied amplitude harmonic, rounded pulse and real-road measured random excitations. The evaluation results illustrate that the proposed SSMC can greatly suppress the vehicle suspension vibration due to uncertainty of the load, and thus improve the ride comfort and handling safety. The study establishes a solid theoretical foundation as the universal control scheme for the adaptive semi-active control of the MR full-vehicle suspension decoupled into four MR quarter-vehicle sub-suspension systems.

LINEAR ACTIVE STRUCTURES AND MODES (Ⅰ) —BASIC CONCEPTS AND PROPERTIES

Some basic concepts about the active structures were firstly explained, and the main subjects to study in the field of active structure dynamics were synthesized. For the linear active structures, the annotations on the modes were done in detail. The physical meanings of the right and left eigenvectors were explained. The right eigenvectors are the modal shapes and the modal responses of an active structure depend on the left ones. The adjoint structure of an active structure was defined and the reciprocity theorem was interpreted. For two active structures, which are adjoint to each other and with the reciprocal gain-matrices, the right and left eigenvector are reciprocal. The relationship between an active structure and the corresponding passive structure is expressed with the transfer functions, which is employed to resolve the estimation problems.

Synchronization of different chaotic systems via active radial basis functions sliding mode controller

This paper presents a new method to synchronize different chaotic systems with disturbances via an active radial basis function （RBF） sliding controller. This method incorporates the advantages of active control, neural network and sliding mode control. The main part of the controller is given based on the output of the RBF neural networks and the weights of these single layer networks are tuned on-line based on the sliding mode reaching law. Only several radial basis functions are required for this controller which takes the sliding mode variable as the only input. The proposed controller can make the synchronization error converge to zero quickly and can overcome external disturbances. Analysis of the stability for the controller is carried out based on the Lyapunov stability theorem. Finally, five examples are given to illustrate the robustness and effectiveness of the proposed synchronization control strategy.

LINEAR ACTIVE STRUCTURES AND MODES (Ⅱ) —DISCRETE SYSTEMS AND BEAMS

The basic concepts about the active structures and some attributes of the modes were presented in paper “Liner Active Structures and Modes]( I) ". The characteristics of the active discrete systems and active beams were discussed, especially, the stability of the active structures and the orthogonality of the eigenvectors. The notes about modes were portrayed by a model of a seven-storeyed building with sensors and actuators. The concept of the adjoint active structure was extended from the discrete systems to the beams that were the representations of the continuous structures. Two types of beams with different placements of the measuring and actuating systems were discussed in detail. One is the beam with the discrete sensors and actuators, and the other is the beam with distributed sensor and actuator function. The orthogonality conditions were derived with the modal shapes of the active beam and its adjoint active beam. An example shows that the variation of eigenvalues with feedback amplitude for the homo-configuration and non-homo-configuration active structures.

Researching in Execution Modes for Concurrent Active Rules

It is known as Coupling Modes that how the rule in active database system is triggered to ex-ecute by rule monitor when some special events occurs. In general, the Coupling Modes may be divided into immediate, deferred and detached modes in active database systems. This paper clas-sifies the coupling modes into syn-coupling and asyn-coupling modes, according to the key issue, synchrony/asynchrony, in parallel programming language. Rule execution semantics for various coupling modes is distinctly defined. It is beneficial to implementation and usage of the active rule system. After graph-based rule system (E-RG) and its execution modei, which have been re-searched in their previous works, are chiefly described, the authors show the various strategies to construct the syn-coupling and asyn-coupling modes in E-RG rule system, based on semantics for coupling modes.

Safety of active auditory implants in magnetic resonance imaging

Magnetic resonance imaging(MRI)has become the gold standard for the diagnosis of many pathologies.Using MRI in patients with auditory implants can however raise concerns due to mutual interactions between the implant and imaging device,resulting in potential patient risks.Several implant manufacturers have been working towards more MRI safe devices.Older devices are however often labelled for more stringent conditions,possibly creating confusion with patients and professionals.With this myriad of different devices that are implanted in patients for lifetimes of at least 20 years,it is crucial that both patients and professionals have a clear understanding of the safety of their devices.This work aims at providing an exhaustive overview on the MRI safety of active auditory implants.The available industry standards that are followed by manufacturers are outlined and an overview of the latest scientific developments focusing on the last five years is provided.In addition,based on the analysis of the adverse events reported to the Food and Drug Administration(FDA)and in literature within the past ten years,a systematic review of the most commonly occurring issues for patients with auditory implants in the MRI environment is provided.Results indicate that despite the release of more MRI conditional active hearing implants on the market,adverse events still occur.An extensive overview is provided on the MRI safety of active auditory implants,aiming to increase the understanding of the topic for healthcare professionals and contribute to safer scanning conditions for patients.

Research on Active Safety Methodologies for Intelligent Railway Systems

Safety is essential when building a strong transportation system.As a key development direction in the global railway system,the intelligent railway has safety at its core,making safety a top priority while pursuing the goals of efficiency,convenience,economy,and environmental friendliness.This paper describes the state of the art and proposes a system architecture for intelligent railway systems.It also focuses on the development of railway safety technology at home and abroad,and proposes the active safety method and technology system based on advanced theoretical methods such as the in-depth integration of cyber–physical systems(CPS),data-driven models,and intelligent computing.Finally,several typical applications are demonstrated to verify the advancement and feasibility of active safety technology in intelligent railway systems.

Study on Active Principle and Modernization of Chinese Drugs

The people as a whole cannot live for one day without drug, and the requirement of drugs would never come to an end or stay on the same level. Pharmaceutical industry, being of great significance, has become a new and important one in economic growth in the 21st century. Therefore, the modernization of Chinese drugs has also become a hot spot in public opinion in recent years.

Modelling of Active and Latent Attributes Based on Traveler Perspectives: Case of Port City of Douala

A growing stream of study stresses the relevance of subjective elements in understanding the hierarchy of preferences that underpin individual travel behavior. The purpose of this study is to evaluate the impact of various factors on mode choice. To achieve this, a multinomial logit model (MNL) was used to analyze the relationships between mode choice and three classes of attributes;Combined Active and Latent, Active only and Latent only attributes. The data used are derived from surveys in the port city of Douala, Cameroon as a case study. Results stipulated that, the combined attributes model performed better than both active only attributes and latent only attributes models. Likewise, latent only attributes model performed better than active only attributes model. The advantage of modelling all three groups is for better selection of the most relevant attributes, and this is very relevant in understanding travel behavior of individuals and mode choice decisions.

An Active-Only Temperature-Insensitive Current-Mode Biquad Filter Based on Differentiator Structures Employing CCCCTAs

This article presents an active-only current-mode universal biquad filter performing three standard functions: low-pass, high-pass and band-pass function, which can be readily modified to achieve the rest functions (band-stop and all-pass). The circuit principle is based on active-only circuit designed by using differentiators which are constructed from current controlled current conveyor transconductance amplifier (CCCCTA) cooperating with an internally frequency compensated operational amplifier (OA). The features of the circuit are that: the pole frequency and quality factor can be independently tuned via the input bias currents and it is ideally temperature-insensitive, its circuit description is very simple, consisting of 3 CCCCTAs and 2 operational amplifiers, and the proposed circuit is very appropriate for further developing into integrated circuit architecture. The PSpice simulation results are shown. The given results agree well with the theoretical anticipation.

Mode of Action and Cytotoxicity of Bioactive Compounds Produced by Streptomyces sp. KB1

Rapid emergence of methicillin-resistant Staphylococcus aureus (MRSA) has led to search of a novel bioactive compounds from natural resources. This study was aimed to determine the mode of action of bioactive compounds produced by Streptomyces sp. KB1 TISTR 2304 against MRSA, including cytotoxicity against mature brine shrimp. The mode of action and cytotoxicity of bioactive compounds were performed by observing the tested MRSA cells with a scanning electron microscope and evaluated by the brine shrimp lethality bioassay, respectively. The results indicated that bioactive compounds had the mode of action at the cell wall and also showed the moderate cytotoxic activity. This study concluded that the bioactive compounds produced from strain KB1 can be used as a model for novel anti-MRSA drug development.

Active Tectonic Research for Seismic Safety Evaluation of Long-Line Engineering Sites in China

Long-line engineering sites usually have to pass through active tectonics, so the research of active tectonics is of great importance to seismic safety evaluation of this sort of site. In the paper, basing on the summarization and analysis of the requirements for seismic safety evaluation of long-line engineering site and the status quo of active tectonics research, we propose the focal points of active tectonics research for seismic safety evaluation of long-line engineering sites, including the research contents, technical targets and routes, and the submission of the achievements, etc. Finally, we make a preliminary analysis and discussion about the problems existing in the present-day active tectonics research for seismic safety evaluation of long-line engineering sites.

Simulation research of discrete sliding mode control for active power filter

Because of the widely-used nonlinear loads, the problems of harmonics and low power factor in power systems are becoming more and more serious. In view of the above problems, a shunt three-phase active power filter （SAPF） based on discrete sliding mode control to suppress the harmonics was designed and the power factor improved. First, built the mathematical model of SAPF. Then, controlled the switch through analyzing the harmonic current that was controlled signal using discrete sliding mode control. Through simulation using MATLAB, verified the validity of the algorithm. By the simulation waveforms, it can be found that after the load current containing a large number of harmonics passes the active power filter, the waveform of the power current approximately becomes a sine wave and the harmonics is significantly reduced. As a result, it plays a good role in purifying power systems. Moreover, from the waveforms of harmonic current and power current, it can be found that the algorithm has a faster tracking speed. The waveform can fect.

Skyhook Surface Sliding Mode Control on Semi-Active Vehicle Suspension System for Ride Comfort Enhancement

A skyhook surface sliding mode control method was proposed and applied to the control on the semi-active vehicle suspension system for its ride comfort enhancement. A two degree of freedom dynamic model of a vehicle semi-active suspension system was given, which focused on the passenger’s ride comfort perform-ance. A simulation with the given initial conditions has been devised in MATLAB/SIMULINK. The simula-tion results were showing that there was an enhanced level of ride comfort for the vehicle semi-active sus-pension system with the skyhook surface sliding mode controller.

Nth Order Voltage Mode Active-C Filter Employing Current Controlled Current Conveyor

This paper proposes an nth order (where n = 2,3, ,n) voltage mode active-C filter using n number of current controlled current conveyors (CCCIIs) and n number of equal valued grounded capacitors. The proposed topology can implement both band pass and low pass responses without alteration of any components. The filters offer the following important features: use of minimum number of current controlled current conveyors (CCCIIs) and passive components, no matching constraint, use of all grounded capacitors and absence of external resistor suitable for integration, cut off frequency can easily be electronically adjusted using AMS 0.35 μm CMOS technology. PSPICE simulation results of third order band pass and low pass responses are provided. The results are found to agree well with the theory.