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The viscoelastic material is one of most popular shock absorbing materials for mitigating vibrations of building structures due to earthquake. Its dynamic performance is affected by the temperature, the excitation frequency and the excitation amplitude. Therefore, in order to study the non-linear dynamic performance of the viscoelastic materials, a hybrid test system using the electric exciter is proposed, in which the electric exciter is the actuator, MATLAB is used for the simulation of the numerical substructure and the communication between the upper computer and the lower machine, and STM32 single-chip microcomputer is used to control the work state of the electric exciter. Based on the equivalent force control method and the incremental PID control algorithm, a controller is designed to make sure the electric exciter produces accurate control forces to the non-linear test component in the physical substructure. It can be shown from the test results that the developed whole hybrid test system is feasible and effective.

Haloacetamides (HAcAms) are an emerging class of nitrogenous disinfection by-products (

The magnetorheological (MR) damping material is a kind of smart shock absorption material, and it can be made into MR dampers for reducing the vibration or dynamic response of structures. During the vibration mitigation control of structures with MR dampers, the displacement and acceleration responses are always concerned firstly because the displacement responses determine the safety of structures and, at the same time, the acceleration responses determine the comfort level of the human body staying in structures. That means, the control currents choice of MR dampers during the vibration process is a multi-objective optimization control problem. In this paper, the particle swarm optimization (PSO) algorithm is developed to control the displacement and acceleration responses simultaneously. Numerical analysis for a five-floor steel frame structure with one MR damper installed on each floor is carried out. Simulation results of the PSO control structure are compared with those of passive control (including the ON-control and the OFF-control) structures and the uncontrolled structure. Analysis results demonstrate that the PSO algorithm can reduce the displacement responses of the structure obviously and, at the same time, it can reduce the acceleration responses of the structure to a certain extent. Furthermore, the PSO algorithm reduces the seismic responses of structures more effectively than those of passive control structures.

Viscoelastic dampers are one of the most popular earthquake mitigation devices for building structures with a large number of applications in civil engineering. The seismic performance of viscoelastic dampers is greatly affected by viscoelastic materials. The present paper addresses the theoretical and experimental studies of the viscoelastic damper. The regular polyhedron chain network models for viscoelastic materials are proposed based on the molecular chain network microstructures and the temperature–frequency equivalent principle. Several dynamic property tests for the viscoelastic damper at different temperatures, frequencies, and displacements are carried out, and the proposed models are verified by comparing the numerical and experimental results. The comparisons show that the viscoelastic damper has perfect energy dissipation capacity, and the regular polyhedron chain network models can well describe the mechanical properties of the viscoelastic damper at different environmental temperatures and excitation frequencies.

Performance tests of magnetorheological (MR) dampers show that the hysteresis curves generally show an obvious force–lag phenomenon, which is due to the presence of trapped air in the working chamber of the damper. However, the force–lag phenomenon is barely considered in existing studies, and its influence on the seismic performance of MR damped structures is still unclear. In this paper, experimental and theoretical research have been carried out to analyze the force–lag phenomenon and its influence. Firstly, a specially designed MR damper was manufactured so that MR fluid can be poured into the damper successively for several times until the working chamber was filled, and performance tests were carried out correspondingly with different MR fluid perfusion densities (a parameter introduced in this paper to describe the volume fraction of MR fluid in the working chamber). The mechanical properties of the MR damper under different MR fluid perfusion densities were compared to reveal the influence of the force–lag phenomenon. Then, the effects of excitation properties on the force–lag phenomenon were discussed by comparing experiments results under different currents, frequencies and displacement amplitudes. Further, a force–lag mathematical model was proposed by considering the variation of the force-lag part with MR fluid perfusion density to reflect the force–lag phenomenon with different volume fractions of trapped air, and then verified based on the performance test data. Finally, numerical analysis of MR damped structures with different MR fluid perfusion densities was performed using the proposed force–lag mathematical model. Results show that the damping effect of MR control systems will be weaken due to the force–lag phenomenon, and with the increase of the MR fluid perfusion density, the seismic performance of MR damped structures will gradually improve.

The bridge stay cable, one of the most critical components in cable-stayed bridges, is vulnerable to vibrations owing to its low inherent damping capacity. Thus effective vibration control technology for bridge stay cables is extremely critical to safe operations of cable-stayed bridges. Several countermeasures have been presented and/or implemented to mitigate this vibration; however the passive method can only add a small amount of damping to the cables, excessive energy demand of active control devices severely limits its practicality, the semi-active control methods still have the drawbacks of complex state estimation module and a large amount of control algorithm calculation. This paper proposes a practical magnetorheological pseudo negative stiffness (MR-PNS) control system coupled with control strategy for bridge stay cables. The current reference point is introduced in the dynamic modeling of the MR-PNS control system to characterize the current control strategy. This paper investigates the adjustable of MR-PNS control system performance and energy consumption caused by different current strategies. Taking the vibration control of the Nanjing Second Yangtze River Bridge J20 cable as an example, the simulation results highlight the advantages of the MR-PNS control system that the failure area is small, the quasi-optimal area is wide, and it can still keep sort of vibration damping performance in the degenerate area. The model cable vibration control test proves the feasibility and efficiency of the single input MR-PNS bridge stay cables control method.

Hybrid simulation is an advanced structural dynamic experimental method that combines experimental physical models with analytical numerical models. It has increasingly been recognised as a powerful methodology to evaluate structural nonlinear components and systems under realistic operating conditions. One of the barriers for this advanced testing is the lack of flexible software for hybrid simulation using heterogeneous experimental equipment. In this study, an electrodynamic fatigue test machine is made and a MATLAB program is developed for hybrid simulation. Compared with the servo-hydraulic system, electrodynamic fatigue test machine has the advantages of small volume, easy operation and fast response. A hybrid simulation is conducted to verify the flexibility and capability of the whole system whose experimental substructure is one spring brace and numerical substructure is a two-storey steel frame structure. Experimental and numerical results show the feasibility and applicability of the wh...

Magnetorheological (MR) damper is a semi-active control device designed by utilizing the instantaneous fluid-solid conversion characteristics of MR fluid, thus the microstructure of MR fluid fundamentally determines the mechanical properties of MR dampers. In order to study the influence of MR fluid microstructure on the macroscopic mechanical properties of MR dampers, a micro-macro mathematical model for MR dampers was proposed to describe the dynamic properties of MR dampers affected by the microstructure of MR fluid. Firstly, the micromodel of MR fluid was brought into classic quasi-static model and the double-Sigmoid model to propose a mathematical model, which considers the MR fluid microstructure by expressing the yield force parameter in the traditional double-Sigmoid model with the microstructure parameters of MR fluid. By analyzing the data of the performance test of a single-coil MR damper, the parameters of the proposed mathematical model were fitted. The proposed micro-macro model for MR dampers was verified by comparing the results calculated by this model with the performance test data. Based on the proposed micro-macro mathematical model, the nonlinear hysteretic curves with different MR fluid microstructure parameters can be numerically analyzed and compared. Finally, the influences of the volume fraction, size, and coating thickness of ferromagnetic particles on the mechanical properties of MR dampers were revealed and discussed. The research can provide guidance for the preparation and formulation optimization of high-performance MR fluid.

To truly reflect the influence on structural seismic response control using viscoelastic dampers with strong nonlinear properties and reduce the cost and difficulty of experimental research, a new user-programmable hybrid simulation platform is developed. The core implementation details of this platform, including the core architecture, software system, and testing setup, are described. To better realize accuracy and stability of the hybrid simulation experiment, methods for solving the equivalent force equilibrium equation for hybrid simulation experiments on viscoelastically damped structures are proposed. Then, the mechanical properties of the experimental substructure (viscoelastic damper) are tested under different temperatures, amplitudes and frequencies, and the mathematical model parameters of the experimental substructure are identified. A seismic response comparison of viscoelastically damped structures obtained by the hybrid simulation experiment and the time history analysis verifies the robustness and reliability of the hybrid simulation platform to test nonlinear systems. Lastly, a series of hybrid simulation experiments for viscoelastically damped structures under different temperatures, seismic intensities and seismic waves are implemented using this hybrid simulation platform for the first time. The experimental results reveal the influence on structural seismic response control by viscoelastic damper under different temperatures, seismic intensities and seismic waves.

A unique bio-inspired multi-joint leg-like or limb-like vibration isolation structure is studied by mimicking the skeleton and joint structures of animal legs, and its advantage in passive vibration isolation is systematically investigated. This bio-inspired structure uses several small quadrilateral structures composed by short adjustable rods and a transverse spring to simulate the multi-articulation of animal legs and adopts long rods to simulate the skeleton. The equivalent static stiffness property, loading capacity and dynamic vibration isolation performance of the structure are systematically studied. It is shown that the nonlinear stiffness characteristics of the structure can lead to very excellent vibration isolation capability in the low-frequency band. Different from many existing quasi-zero-stiffness (QZS) isolators in the literature, this novel anti-vibration structure can demonstrate superior high static but low dynamic stiffness (HSLDS) property and thus excellent vibration isolation performance, subject to large vibration amplitude. Through adjusting proper structural parameters including the rod-length, assembly angle, spring stiffness and layer number according to the influence of the structural parameters on the nonlinear stiffness property, the new structure can have the optimal vibration isolation performance without sacrificing its loading capacity to meet actual requirements. Especially, the length of long rods which is used to simulate the skeleton can be adjusted to obtain better vibration isolation performance than adjusting other parameters, followed by the adjustment of the parameters of small quadrilateral structures. The analysis of the influence of structural parameters on the vibration isolation performance shows that the symmetry between different layers has an important role in maintaining the characteristic of the HSLDS. The comparison with other existing vibration isolation structures of the QZS property also indicates that, the new vibration isolation structure can have a better vibration isolation performance with relatively a smaller size of the overall structure. Experiments are successfully conducted and validated the beneficial nonlinear properties of the structure. This novelbio-inspired anti-vibration structure would have great advantages in practical engineering applications.

The magnetorheological (MR) fluid is a typical smart material, whose shear yield stress can be adjusted through changing the strength of external magnetic field, and the changing process only takes a few milliseconds. The MR fluid is composed of micro/nanometer ferromagnetic particles, carrier fluids, and some additives. Among them, the performance of ferromagnetic particles will mainly affect the sedimentation stability and the magnetic saturation of the MR fluid. Therefore, the ferromagnetic particles are expected to have characteristics of both low density and high magnetism. In this paper, the multi-walled carbon nanotubes (MWNTs) were adopted to coat on the carbonyl iron (CI) particles with grafting technology using ultrasonication and mechanical stirring. The coated CI particles with perfect core-shell structure were developed and the influence of the dosages of grafting agent and MWNTs were tested. And then, MR fluids with CI particles coated with MWNTs were established and the coating effect was studied through surface topography particle density, and magnetic properties of composite magnetic particles and stability tests of the prepared MR fluids. The results showed that although the magnetic saturation of the prepared MR fluids with CI particles coated with MWNTs would reduce slightly, the particles density and the adsorption force between the particles were decreased effectively, which are both advantageous to the improvement of the sedimentation stability of MR fluids.

Photochemical degradation of typical phthalate esters, as, e.g. dimethyl phthalate (DMP), in water by the UV/H2O2 process was investigated. The degradation rate of DMP was affected by several reaction factors, including initial DMP concentration, H2O2 concentration, UV light intensity, and coexisting cations and anions. The DMP degradation rate decreased with increasing initial DMP concentration. Carbonate ions significantly reduced the reaction rate by 70.2%, while the degradation rate was improved ten-fold in the presence of ferric ions. The initial reaction mechanism and possible degradation products were investigated using density functional theory (DFT), including B3LYP and M062X hybrid functional. The addition of OH radicals (OH•) to the C4 position of the DMP ring is energetically favored for the initial reaction of DMP with OH•. Dimethyl 4-hydroxyphthalate (DMP-4OH) is one of the initial degradation intermediates. A possible reaction mechanism was also proposed based on GC/MS analysis and quantum chemical calculations. The formation of DMP-4OH has been explained by quantum chemical calculations, which indicates the advantage and promising role of this method in the degradation mechanism analysis.

The control algorithm is the core aspect to realize vibration mitigation effectively for the intelligent system. In this chapter, equations of the motion of an intelligent vibration control system are introduced firstly, and fundamental theories of different control algorithms for intelligent vibration control system are introduced in detail. At the same time, the advantages and disadvantages of each algorithm are summarized as well as its applicable condition.

In this chapter, design and parameters optimization on intelligent control devices are introduced. Magnetorheological (MR) damper and MR elastomer are designed optimally as examples of semi-active control devices. The active control devices are also designed based on the control force optimization.

The basic principle of semiactive intelligent control method is introduced firstly, and then the commonly used semiactive control devices, such as magnetorheological (MR) damper, electrorheological damper, piezoelectricity friction damper, semiactive-varied stiffness damper, semiactive-varied damping damper, and MR elastomer device, are introduced in detail including basic principles, construction and design, mathematical model, analysis and design methods, test and applications.

The analytical method of the structures incorporated with magnetorheological (MR) dampers, including the elastic analysis and elasto-plastic analysis, is introduced. In this chapter, taking the building structure with MR dampers as an example, the models of the structure and dampers will be discussed. Finally, the dynamic response analysis method based on SIMULINK is introduced.

The control algorithm and theoretical dynamic analysis method of the intelligent controlled structure have been presented in detail in the previous chapters; this chapter will focus on the specific numerical examples. The building structure with magnetorheological (MR) dampers, the bridge with MR dampers, and the platform with MR elastomer devices are chosen to evaluate the control effects of the semiactive intelligent control devices. The building structure with active tendon system is taken as an example to verify the control effect of active control.

The intelligent vibration control strategies are applied to real structures through the intelligent controller, thus the hardware design of the intelligent controller is very important to the effectiveness of intelligent control of civil engineering structures. In this chapter, the intelligent controller of magnetorheological dampers is taken for example to introduce the hardware design method of intelligent controllers, and then experimental study is carried out to verify the effectiveness of the intelligent controllers.

In this chapter, principles and classifications of active intelligent control systems are introduced firstly, and basic contents of the active mass control system and active tendon control system, including the basic principles, the mathematical model, structural analysis, and engineering examples are presented. Finally, other active intelligent control systems are introduced briefly.

Aeroengine controller is a crucial and complex component aimed at pursing optimal performance while satisfying all kinds of physical and operational constrains. A novel control technique, multivariate constrained predictive control based on linear state space model, is applied to a commercial turbofan engine. To be specific, according to the control requirements of turbofan engine, its outputs are classified into two types, controlled or constrained; they are then incorporated into the cost function and the inequality constraint condition of baseline MPC algorithm respectively. Further, since key parameters of MPC play an important role in obtaining optimal performance, their selection is studied. It is shown that control performance using improved MPC is better than that of PID controller for a big disturbance while maintaining within prescribed constrains.

A comparative study is conducted on a class of typical X-shaped structures to explore critical design parameters in passive vibration isolation. Several benchmark X-shaped structures are therefore studied, considering the effects of several critical structural parameters on potential vibration isolation performance in different cases. Theoretical calculations, finite element simulations and experimental results show that this class of X-shaped structures in vibration isolation is critically affected by the ratio between the horizontal displacement in the installed spring and the vertical displacement of the structure, which is further nonlinearly dependent on the values of other structure parameters. This critical design parameter can act as a convenient optimization objective for selecting structural parameters in various practical applications. The results of this study thus present a new understanding of the nonlinear dynamics of the X-shaped structures which can facilitate the design or parametric selection of these structures in practices.

In this paper the physical and dynamic mechanical property tests of magnetorheological elastomers (MREs) are reported. Two kinds of MREs with different matrices, about 12 samples in total, are fabricated by mixing carbonyl iron powder and additives, and cured by using a constant magnetic field. The physical and dynamic viscoelastic properties of these MRE specimens are evaluated with respect to different magnetic fields, displacement amplitudes, and frequencies. The experimental results demonstrate that MREs have variable stiffness and the loss factor of the samples with bromobutyl rubber is high, which shows a good damping property. The proposed magnetoviscoelasticity parameter model is then verified by comparing the experimental and numerical results, which demonstrate that the magnetoviscoelasticity parameter model can describe the MRE performance well.

Tribological properties of ceramic cutting tool materials in contact with wood based materials were studied in this paper by examining how Al2O3-ceramics and Si3N4-ceramics behave in dry sliding experiment in contact with wood-based materials and by comparing their behavior with tungsten carbide material at the same time. It had been found that the ceramics exhibited much better tribological properties than tungsten carbide material, and Si3N4-ceramic performed better than Al2O3-ceramics. The Al2O3-ceramics with an addition of ZrO2 had better tribological performance than the common Al2O3-ceramics in contact with wood-based materials. The tungsten carbide had better tribological performance than ceramics in tribological contact with wood flour/PE material. A well-marked difference occurred in various cutting materials/MDF frictional pair, but the differences in various cutting materials/PB frictional pair were insignificant. An increase of the normal force didn’t result in any significant decrease of the friction coefficient. An addition of ZrO2 in the Al2O3-ceramics could inhabit corrosive wear.

Tea flushes identification from their natural background is the first key step for the intelligent tea-picking robot. This paper focuses on the algorithms of identifying the tea flushes based on color image analysis. A tea flushes identification system was developed as a means of guidance for a robotic manipulator in the picking of high-quality tea. Firstly, several color indices, including y-c, y-m, (y-c)/(y+c) and (y-m)/(y+m) in CMY color space, S channel in HSI color space, and U channel in YUV color space, were studied and tested. These color indices enhanced and highlighted the tea flushes against their background. Afterwards, grey level image was transformed into binary image using Otsu method and then area filter was employed to eliminate small noise regions. The algorithm and identification system has been tested extensively and proven to be well adapted to the complexity of a natural environment. Experiments show that these indices were particularly effective for tea flushes identification and could be used for future tea-picking robot development.

Persulfate oxidation processes, with and without activation using ultraviolet light (respectively UV/PS and PS) have the potential to degrade anthropogenic chemicals in water. However, little is known about the impact of PS or UV/PS pre-oxidation on downstream formation of disinfection by-products (DBPs). In this study the three antibiotic chloramphenicols (chloramphenicol and two of its analogues [thiamphenicol and florfenicol], referred to collectively as CAPs), which frequently occur in wastewater-impacted source waters used by drinking water treatment plants, were selected as model antibiotic compounds. The formation of carbonaceous and nitrogenous disinfection by-products, including halomethanes, haloacetonitriles and halonitromethanes, during chlorination and chloramination preceded by PS and UV/PS was investigated. No significant concentrations of haloacetonitriles and halonitromethanes were detected during chlorination. During chloramination chloramphenicol formed a considerable amount of dichloronitromethane (e.g., 3.44 ± 0.33% mol/mol at NH2Cl dose = 1 mM) and trichloronitromethane (e.g., 0.79 ± 0.07% mol/mol at NH2Cl dose = 1 mM), compared with THM and HAN formation. PS pre-oxidation achieved a statistically significant reduction in trichloromethane formation from chlorination, and in HAN and HNM formation from chloramination. Although UV/PS slightly increased dichloroacetonitrile formation during chloramination, it significantly decreased dichloronitromethane and trichloronitromethane formation during chloramination. Overall, the use of PS and UV/PS has the potential to have contrasting impacts on DBP formation in heavily wastewater-impacted waters, depending on the disinfection method. Hence, their application needs to be carefully balanced against the downstream effect on DBP formation.

The fuzzy control technology is a kind of intelligent control method, and it has strong robustness. The fuzzy control strategy is used to choose the control currents of MR dampers in this paper. In order to illustrate how to design the fuzzy controller, three kinds of the fuzzy controller having different membership functions and fuzzy rules are designed. A five-floor MR structure using the designed different fuzzy controllers is simulated. Analysis results show that for the MR structure, it is not best that MR dampers provide the maximum forces to the structure, so the displacement and acceleration responses of the structure must be weighed at the same time to make MR dampers provide reasonable forces when the membership functions and fuzzy rules are designed.

The magnetic particles coated with the carbon are used in the magneto-rheological fluids (MRFs) and the coat-like structure slow down the sedimentation of MRFs. Meanwhile, after the performance tests, the new MRF has the low viscosity and good ability of the recovery. These characters have more advantages in the application fields. Based on the prepared MRF, a shearing model that considers the interaction force between the adjacent chains was presented. By applying the proposed model, some conclusions are reached. The volume ratio of the magnetic particles has an important effect on the yield stress of the MRFs. The shear strain where the maximum shear stress happened has something to do with the volume ratio of the magnetic particles.

This paper gives an experimental research on slightly contaminated raw water by utilizing the combined technology of electro-flotation and suspending TiO2 photochemical catalysis. During the static experiment of degrading humic acid by electro-flotation—suspended TiO2 photochemical catalysis, the ratio of CODMn removal reaches 87.8% in such conditions as two ultraviolet germicidal lamps of 10W, the voltage of 20V, the current of 0.4A, 0.5cm intervals of two groups of plates, the TiO2 dosage of 1g/L and the reaction time of 150 minutes. The preferable synergistic effect can be achieved when combining electro-flotation and photocatalytic oxidation together.

By using parallel process of photocatalysis-biological contact oxidation, a research on the pretreatment effect of micro-polluted raw water was conducted. The result indicates that the changes of HRT and the initial concentration take significant impact on the removal of NH3-N. 60min is the best residence time for the pretreatment. Once the thickness of composite media is 120mm, the removal efficiency of CODMn may reach as much as 15.55%, while the average removal efficiency of turbidity is 20%. Since the nitration reaction consumes certain amount of alkalinity, the pH value of outlet water is lower than inlet water. When employing parallel process, biological oxidation and photocatalysis are performed and finished in the same reactor simultaneously, conducing to maintaining a moderate level of the removal of CODMn and NH3-N. All these are of reference value for its application in practical engineering projects.

This paper deals with the synchronization problem of chaotic neural networks with both interval time-varying and distributed time-varying delays. By introducing an improved Lyapunov–Krasovskii functional and employing definition on a convex set, a delay-dependent feedback controller is derived to achieve exponential synchronization with the help of a drive-response concept and a linear matrix inequality method. The addressed time-delays are interval ones and the limitation on the derivative of a time-varying delay being less than 1 is released. Moreover, the activation functions are assumed to be of more general descriptions, which generalizes and improves those existent methods. Finally, three numerical examples are given to show the effectiveness of the synchronization scheme.

In this paper, the global exponential stability is investigated for a class of Cohen–Grossberg neural networks with time-varying and continuously distributed delays. By using an appropriate Lyapunov–Krasovskii functional and equivalent descriptor form, the sufficient conditions are obtained to guarantee the exponential stability of the addressed system. These conditions are expressed in terms of LMIs and can be checked by resorting to the Matlab LMI toolbox. In addition, the activation functions are of more general descriptions and the derivative of a time-varying delay can take any value, which generalize and further improve those earlier methods. Numerical examples are given to show the reduced conservatism of obtained methods.

The control strategy is very important for semi-active control or active control systems. An integrated intelligent control strategy for building structures incorporated with magnetorheological (MR) dampers subjected to earthquake excitation is proposed. In this strategy, the time-delay problem is solved by a neural network and the control currents of the MR dampers are determined quickly by a fuzzy controller. Through a numerical example of a three-storey structure with one MR damper installed in the first floor, the seismic responses of the uncontrolled, the intelligently controlled, the passive-on controlled, and the passive-off controlled structures under different earthquake excitations are analyzed. Based on the numerical results, it can be found that the time domain and the frequency domain responses are reduced effectively when the MR damper is added in the structure, and the integrated intelligent control strategy has a better earthquake mitigation effect.

Magnetorheological (MR) damper is a prominent semi-active control device for earthquake responses mitigation of structures. The most important topic for the intelligent MR structures is choosing the control current of MR dampers quickly and accurately. The typical control strategy is on–off control strategy, i.e. bi-state control strategy, while inherent time-delay and coarse control precision lie in this strategy. This paper proposes neuro-fuzzy control strategy, in which the neural-network technique is adopted to solve time-delay problem and the fuzzy controller is used to determine the control current of MR dampers quickly and accurately. Through comparison between the bi-state control and the neuro-fuzzy control strategies and a numerical example about a three-story reinforced concrete structure, it can be concluded that the control strategy is very important for semi-active control, the neuro-fuzzy control strategy can determine currents of MR dampers quickly and accurately, and the control effect of the neuro-fuzzy control strategy is better than that of the bi-state control strategy.

The magnetorheological (MR) damper, a shock absorption device, can be used to reduce vibration or dynamic response of controlled systems. Its parameters can be adjusted in real-time by updating its control current, therefore, it is critical to determine the control current of the MR damper accurately and quickly. This study proposes a fuzzy control strategy based on a neural network forecasting model of the building structure with MR dampers, in which a neural network forecasting model is developed to predict dynamic responses of the system with MR dampers and a fuzzy controller is then designed to determine control currents of MR dampers. A five-floor steel structure with MR dampers using the proposed fuzzy control strategy is simulated by using Simulink. Simulation results of the fuzzy control system are compared with those of the bi-state control system, the passive-on control system, the passive-off control system, and the uncontrolled system. Analysis results demonstrate that the fuzzy control strategy can determine control currents of MR dampers accurately and quickly; furthermore, the fuzzy control strategy reduces seismic responses of structures more effectively than the passive-on control strategy, the passive-off control strategy, and the bi-state control strategy.

Magnetorheological (MR) dampers are one of the most promising devices for mitigation of vibration of engineering structures due to earthquakes and wind excitation. In this paper, a compact two-column model of an MR fluid is proposed in order to formulate a general solution for calculation of the yield shear stress of an MR fluid. The magnetic induction intensity in the damping gap, which is the key parameter of the compact two-column model, is determined through simulation of the magnetic circuit of the MR damper. To verify the effectiveness and significance of the proposed model, damping forces calculated based on the proposed model and the traditional single-chain model are compared with the experimental data. Results show that the proposed compact two-column model is more accurate and that it can describe the rheological properties of the MR fluids very well.

Magnetorheological (MR) damper has a potential use in the vibration control of large structures due to its lower energy input and fine earthquake mitigation ability. A key problem for controlling structure with MR dampers is choosing the control current quickly and accurately. In order to solve this problem, a new method by using fuzzy controller, namely fuzzy full-state control method, is proposed. Dynamic responses under different inputs of fuzzy controller are compared. At the same time, dynamic responses of the traditional bi-state (BS) controlled structure and the passive full-current (PFC) controlled structure under different earthquake waves are compared with those of fuzzy full-state controlled structure. Through a numerical example about a three-story reinforced concrete structure, it can be concluded that fuzzy control technique can realize choosing of currents of MR dampers quickly and accurately and have good control effect.

Semi-active control of buildings and structures with magnetorheological (MR) dampers for earthquake hazard mitigation represents a relatively new research area. In this paper, the Bingham model of MR damper is introduced, and the formula relating the yielding shear stress and the control current of MR dampers is put forward that matches the experimental data. Then an on-line real-time control method for semi-active control of structures with MR dampers is proposed. This method considers the time-delay problem of semi-active control, which can solve distortion of the responses of structures. Finally, through a numerical example of a three-storey reinforced concrete structure, a comparison is made between controlled structure and uncontrolled structure. The calculated results show that MR dampers can reduce the seismic responses of structures effectively. Moreover, the on-line real-time control method is compared with the traditional elastoplastic time-history analysis method, and the efficacy of the on-line real-time control method is demonstrated. In addition, the Levenberg–Marquardt algorithm is used to train the on-line control neural network, and studies show that the algorithm has a very fast convergence rate.

Batch experiments are used to research selenite removal from groundwater by nanoscale zero-valent iron (nZVI) , and dynamic effects of commonly co-existing anions on the removal of selenite are also investigated. The results showed that under anoxic conditions,when nZVI dose was 0.1 g.L-1 , the concentration of Se( IV)/sodium chloride was 100 micromol.L-1/0. 01 mol L-1 , pH = 7.0, T = 25 degrees C +/- 1 degrees C, auto-adding 1 mmol.L -1 CO(2-)(3) or SO(2-)(4) , 5 mg. L -1 humic acid (HA), the removals of Se( IV ) were obviously inhibited. The weak effect on the removal of Se( IV) was observed when added 0. 5 mmol L- Ca2+ or Mg2 ,while concentrations of Ca2+ and Mg2+ were 3 mmol L-1 and 3 mmol L-1 respectively, removal efficiency of Se( IV) were evidently decreased. Without coexisting ions, Se( IV) were totally removed in 20 min, while with co-existing ions, removal efficiency of Se( NV) were achieved 100% in 30 min. Bivalent iron tended to stationary with the remove of Se( WV) in reaction processes. ORP rapidly decreased from positive to negative in the process of reaction, which illustrated the process of remove Se( IV) by nZVI was the reduction reaction.

Magnetorheological elastomers (MRE) have been synthesized on the basis of a silicon compound and a mixture of carbonyl iron particles of sizes 3–5 and 40–80 μm. Their viscoelastic properties have been studied by dynamic shear oscillations of various amplitudes on a stress controlled rheometer. The magnetic response of the obtained materials has been examined in a magnetic field applied perpendicular to the shear plane. It has been shown that under applied magnetic field both the storage G′ and loss G″ moduli became strain-dependent. The values of G′ and G″ decrease with strain, while their ratio (the loss factor), G″/G′, growths with strain. The higher magnetic field is the more pronounced the strain dependence is. At small strain (up to 1%) MRE demonstrate a giant (more than 10 times) increase of the moduli. Some features of hysteretic behavior of MRE under simultaneously applied magnetic field and external mechanical force have been elucidated. Temperature has a negligible effect on viscoelastic properties and stability of the developed MRE. A damper on the basis of MRE has been designed and its properties have been examined.

Three-dimensional excitation and emission matrix fluorescence spectra (3D-EEM) has attracted the increasing attention of researchers in water monitoring and water treatment areas. The self-organizing map (SOM) is a kind of non-supervised and self-learning neural network with the feature of high self-stability and noise tolerance. In the present paper, SOM technique was employed for the exploratory analysis of EEM spectra of water samples in a water treatment plant The results showed that EEM spectra could be clustered into three classes, corresponding to tryptophan-like protein substances, tyrosine-like protein substances, and UV fulvic-like substances. The three components could be effectively removed during the whole water treatment process with the high removal of 84.6% (tyrosine-like), 79.9% (tryptophan-like), and 69.1% (UV fulvic-like). The results show that SOM technique can be used as an effective tool for EEM spectra analysis, which is helpful for the optimization of water treatment process parameters, the improvement of process performance, and the operation of water treatment plant.

Magnetorheological (MR) damper, a kind of intelligent vibration mitigation device, can be used to reduce the vibration or dynamic responses of structures. Its damping forces can be adjusted in real-time by updating control currents of the MR damper according to the state parameters of the structure. In this paper, a single-chip microprocessor (SCM) for MR damper coupling sensing and control is developed. The SCM has three main functions: the first one is that it can collect the acceleration responses of the structure by using the acceleration sensor in real-time; the second one is that it can use the segmented control strategy to decide the control currents of the MR damper according to the collected acceleration information; the third one is that based on the PWM technology it can realize to accurately supply power for the MR damper. The developed SCM is tested through experiment. The analysis results of the simulation and experiment show that the SCM can collect the state information of the structure in real-time and realize to choose the currents of MR damper accurately to control the damping forces of the MR damper.

The identification work of the aero-engine altitude test is influenced directly by the quality and accuracy of the pressure control of the intake and exhaust. In this paper, these aspects, including: the hardware structure, the software function, the digital PID engineering improvement method of the digital pressure regulation plat, and the GE90-70 based semi-physical simulation test bed construction are introduced in detail. Many advanced control techniques developed for intake and exhaust control system have been applied to the multi-type engine altitude simulation tests successfully, improved the simulation accuracy of the altitude and Mach number greatly, as well as the quality of the simulation.

It is well known that the physical engine components deteriorate gradually due to wear and tear on blades and the casing as an engine operates over time. In this paper, a steady-state model, which takes the component performance deteriorations into account, is developed. The deterioration can be tracked by one Kalman filter. Then the on-board model could be re-constructer based on the estimated values of Kalman filter. After all of this, the on-board model can match with the actual engine. At last a bank of Kalman filters is applied in fault detection and isolation (FDI) of sensors for aircraft gas turbine engine. The engine output values and Kalman filter estimated were used to fault detection and isolation. The proposed approach is applied to a nonlinear engine in this paper, the simulation results indicate that the proposed FDI system is promising for reliable diagnostics of aircraft engines.

In this paper, a robust Kalman filter and a bank of Kalman filters are applied in fault detection and isolation (FDI) of sensor and actuator for aircraft gas turbine engine. A bank of Kalman filters are used to detect and isolate sensor fault, each Kalman filter is designed based on a specific hypothesis for detecting a specific sensor fault. In the event that a fault does occur, all filters except the one using the correct hypothesis will produce large estimation errors, from which a specific fault is isolated. When the Kalman filter is used, failures in the sensors and actuators affect the characteristics of the residual signals of the Kalman filter. While a Robust Kalman filter is used, the decision statistics changes regardless the faults in the sensors or in the actuators, because it is sensitive to sensor fault but insensitive to actuator fault. The proposed FDI approach above, is applied to a nonlinear engine simulation in this paper, and the evaluation results show that this approach to detect and isolate sensor and actuator faults is demonstrated.