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© 2017 IEEE. The magnetorheological (MR) pin joint is a semi-active control device which can be installed in the column-beam structures for structural vibration control. Nevertheless, the nonlinear response of the MR pin joint together with its unique rheological nature makes the device modeling difficult and impedes its engineering application. Although many complicated phenomenal models have been proposed to illustrate the dynamic behaviour of MR devices, a large number of model parameters and differential equations bring the challenges for model identification and controller design. In this study, we try to predict the dynamic response of a MR pin joint using a novel and simple phenomenal model, which is comprised of a rotary spring, a rotary damper and a sigmoid function-based hysteresis component. Then, the model parameters are identified using trust-region-reflective least squares algorithm in MATLAB optimization toolbox. Finally, the experimental results under various loading conditions are used to validate the performance of the proposed model.

Reversible logic circuits are of high interests to calculate with minimum energy consumption having applications in low-power CMOS design, optical computing and nanotechnology, especially in quantum computer. Quantum computer requires quantum arithmetic. A new design of a reversible arithmetic logic unit (reversible ALU) for quantum arithmetic has been proposed in this article. As we known, ALU is an important part of central processing unit (CPU) as the execution unit. So this article provides explicit construction of reversible ALU effecting basic arithmetic operations. By provided the corresponding control unit, the proposed reversible ALU can combine the classical arithmetic and logic operation in a reversible integrated system. This article provides a new more powerful ALU which contains more functions and it will make contribute to the realization of reversible Programmable Logic Device (RPLD) in future using reversible ALU.

Over the past few decades, wireless sensor networks have been widely used in the field of structure health monitoring of civil, mechanical, and aerospace systems. Currently, most wireless sensor networks are battery-powered and it is costly and unsustainable for maintenance because of the requirement for frequent battery replacements. As an attempt to address such issue, this article theoretically and experimentally studies a compression-based piezoelectric energy harvester using a multilayer stack configuration, which is suitable for civil infrastructure system applications where large compressive loads occur, such as heavily vehicular loading acting on pavements. In this article, we firstly present analytical and numerical modeling of the piezoelectric multilayer stack under axial compressive loading, which is based on the linear theory of piezoelectricity. A two-degree-of-freedom electromechanical model, considering both the mechanical and electrical aspects of the proposed harvester, was developed to characterize the harvested electrical power under the external electrical load. Exact closed-form expressions of the electromechanical models have been derived to analyze the mechanical and electrical properties of the proposed harvester. The theoretical analyses are validated through several experiments for a test prototype under harmonic excitations. The test results exhibit very good agreement with the analytical analyses and numerical simulations for a range of resistive loads and input excitation levels. © 2014 The Author(s).

This paper presents the design and evaluation of a novel permanent magnet (PM) energy harvesting system for scavenging electrical energy from ambient vibrations. A two-phase tubular linear PM vibration energy harvester consisting of a mover attached with permanent magnets and a slotted stator with built-in two-phase electromagnetic coils is proposed to convert vibrational kinetic energy into electrical energy. Aiming at maximizing the efficiency of vibrationto-electrical energy conversion under designated vibration and limited space requirement, a systematic research, including innovative device design, theoretical modelling and analysis, and finite element evaluation on the PM vibration energy harvester will be presented in this paper. In addition, the methodology of winding the two-phase coils in slotted stator is explicated in order to fully utilize the harvested electrical energy. A two-phase rectifier circuit is developed to convert the alternative voltage generated by the PM harvester into DC voltage that can be used directly by the external resistive load. Simulation results indicate that the proposed linear PM vibration energy harvesting system is able to generate about 100 watt DC electrical power under the vibration with the velocity of 0.4 m/s and the output electrical power is proportional to the levels of vibration excitations.

Advanced sewage treatment by microalgae is regarded as a promising method for addressing eutrophication. To improve sewage treatment, three kinds of plant hormones including auxin (indole-3-acetic acid, IAA), cytokinin (Zeatin), and brassinosteroid, were chosen to measure the influence of plant hormones on nitrogen and phosphorus removal by Tetraselmis cordiformis and to analyze their mechanisms, including photosynthesis, nutrient metabolism, and gene transcription. The results indicated that the maximal removal efficiencies of total nitrogen and phosphate by T. cordiformis were elevated by the plant hormones by 184.3% and 53.2%, respectively. The chlorophyll a content was increased by 1.1 times by the plant hormones in comparison with the control. Moreover, after being stimulated by plant hormones, the activities of nitrate reductase (NR) and glutamine synthetase (GS) increased by 90.4% and 82.1%, respectively, in comparison with the control. Supplementation with plant hormones also significantly elevated the mRNA expression level of GS-related gene by 30.9%. This study demonstrated that plant hormones could significantly promote the nutrient removal of microalgae for sewage treatment in artificial laboratory conditions and provided theoretical support for its further practical full-scale application under variable conditions.

Self-sensing concrete combines electrically conductive filler material and conventional building material together, and is able to realise a sensing function that by measuring the change of electrical properties of the composite under external loading, the stress, deformation and damage could be monitored. It has the advantages of high sensitivity, long service period, excellent compatibility, durability and mechanical strength, and low maintenance cost, and can be potentially applied in structure health monitoring, weight in motion, traffic detection, parking management and many other fields. This paper overviews the details of the composition and role of each component, the fabrication method and the mechanism of the self-sensing concrete. The future prospects are discussed at the end of the paper.

© 2016 The Korean Society of Rheology and Springer. In this paper, a comprehensive review of the present literature on energy generated magnetorheological (MR) fluid based damper, modeling and applications of the MR damper are presented. The review starts with an introduction of the basic of MR fluid and their different modes, consequences with different types of MR fluids based devices, and their relevant applications. Besides, various forms of MR damper and its applications are presented. Following this, the modeling of the MR fluids and the modeling of the MR fluid based damper are deliberated according to arrangement and configurations. Finally, the review ends with the design and advancement issues, performance analysis matters, and analytical modeling of energy generated magnetorheological fluid damper systems.

© 2016 IOP Publishing Ltd. In recent years, an adaptively tuned magnetorheological elastomer (MRE) isolator for a base isolation system has been designed and tested with the benefits of low power cost, fail safe manner and fast responses. To make full use of this striking device for design of smart structures, a highly precise model should be developed to effectively and accurately forecast the shear force of the device in real-time so as to adopt a proper control strategy to improve the responses of the protected structures. In this work, a novel mechanical model is presented to characterize this nonlinear hysteresis for its implementation in structural vibration control. This model employs the displacement and velocity of the device as well as the applied current as the inputs and just has the limited constant parameters to be identified compared with some classical hysteretic models such as Bouc-Wen, improved Dahl and LuGre models. Performance evaluation of this novel hysteresis model has been conducted based on the testing data from an MRE base isolator. The results show that the proposed model has high modelling accuracy and is able to perfectly portray the unique and complicated behaviours of the device with various excitations.

© 1996-2012 IEEE. Magnetorheological (MR) devices have been quite promising for semiactive control, thanks to their capability of adjusting structural parameters, under a low-power control signal, to effectively withstand severe dynamic loadings including seismic events. MR devices, using visco-elastic and ferromagnetic materials, are subject to hysteresis, which may degrade the performance of smart structures. Therefore, this multivalued nonlinearity needs to be properly modeled and characterized for control and health monitoring. As engineering structures operate as low-pass filter in normal conditions, it is suitable to use the classical describing function (DF) method for modeling and analysis of the hysteretic behaviors in MR device-based smart structures. Data obtained from characterizing tests are recorded in look-up tables to obtain the DFs for these devices, using a curve-fitting technique. The proposed DFs are then useful in structural frequency analysis. Experimental results are reported for a steel beam with MR pin joints subject to quake-induced vibrations provided by a shake table.

© The Author(s) 2015. A magnetorheological absorber is capable of actively adapting any gun recoil condition by means of controlled Coulomb force. The objective of multi-coil magnetorheological absorber with individual input currents is to mitigate the peak force transferred to the buffer structure during bullet firing, and thus to increase the structural fatigue life. This article investigates various cases by applying random combinations of input currents to the magnetic coils. The impact tests were conducted by obtaining and analyzing the force, displacement, and velocity. As a reference, input currents with equivalent magnitude are considered statistically, in terms of average peak force and occurrence time. The experimental results show that separately controlled multi-coils contribute to the magnitude and occurrence time of peak force significantly. Furthermore, to reduce peak forces, a simple open-loop control strategy was proposed and validated effectively by the experimental results.

Reversible logic is a new rapidly developed research field in recent years, which has been receiving much attention for calculating with minimizing the energy consumption. This paper constructs a 4×4 new reversible gate called ZRQ gate to build quantum adder and subtraction. Meanwhile, a novel 1-bit reversible comparator by using the proposed ZRQC module on the basis of ZRQ gate is proposed as the minimum number of reversible gates and quantum costs. In addition, this paper presents a novel 4-bit reversible comparator based on the 1-bit reversible comparator. One of the vital important for optimizing reversible logic is to design reversible logic circuits with the minimum number of parameters. The proposed reversible comparators in this paper can obtain superiority in terms of the number of reversible gates, input constants, garbage outputs, unit delays and quantum costs compared with the existed circuits. Finally, MATLAB simulation software is used to test and verify the correctness of the proposed 4-bit reversible comparator.

Synoptic water sampling at a fixed site monitoring station provides only limited ‘snap-shots’ of the complex water quality dynamics within a surface water system. However, water quality often changes rapidly in both spatial and temporal dimensions, especially in highly polluted urban rivers. In this study, we designed and applied a continuous longitudinal sampling technique to monitor the fine-scale spatial changes of water quality conditions, assess water pollutant sources, and determine the assimilative capacity for biochemical oxygen demand (BOD) in an urban segment of the hypoxic Wen-Rui Tang River in eastern China. The continuous longitudinal sampling was capable of collecting dissolved oxygen (DO) data every 5 s yielding a ~11 m sampling interval with a precision of ±0.1 mg L−1. The Streeter and Phelps BOD-DO model was used to calculate: (1) the oxygen consumption coefficient (K1) required for calibration of water quality models, (2) BOD assimilative capacity, and (3) BOD source and load identification. In the 2014 m river segment sampled, the oxygen consumption coefficient (K1) was 0.428 d−1 (20°C), the total BOD discharge was 916 kg d−1, and the BOD assimilative capacity was 382 kg d−1 when the minimum DO level was set to 2 mg L−1. In addition, the longitudinal analysis identified eight major drainage outlets (BOD point sources), which were verified by field observations. This new approach provides a simple, cost-effective method of evaluating BOD-DO dynamics over large spatial areas with rapidly changing water quality conditions, such as urban environments. It represents a major breakthrough in the development and application of water quality sampling techniques to obtain spatially distributed DO and BOD in real time. Copyright © 2012 John Wiley & Sons, Ltd.

In this article, an MRD50 type of large-scale magnetorheological shock absorber was designed and manufactured in Smart Materials and Structures Laboratory of Nanjing University of Science and Technology. Upon providing a brief background on magnetorheological dampers, the detailed structure of this developed large-scale magnetorheological shock absorber was depicted. A suit of hardware-in-the-loop simulation platform under high impact load excitation was introduced for a weapon system. A series of tests were conducted to establish the dynamic behaviors of magnetorheological shock absorber under impact loads. The test results show that the inertia damping force should not be ignored like a common magnetorheological damper because of the large acceleration from the impact load. Based on the theory model and the experimental data, index parameters of magnetorheological fluid and other structural parameters in Herschel-Bulkley-Inertia model were identified by using the least square algorithm. In order to evaluate the controllability of large-scale magnetorheological shock absorber applied into high impact loads, three control algorithms, including on-off control, proportional-integral-derivative control, and fuzzy control algorithm, were used in tests to control the dynamic behavior of magnetorheological shock absorber, and some results of the controllability tests were exhibited in this article. In conclusion, the results indicated that the developed large-scale magnetorheological shock absorber was indeed able to effectively control the recoil dynamics. © The Author(s) 2012.

Magnetorheological fluid (MRF) has received significant attention lately and MRF based devices have been proposed for structural control applications in recent years. The unique characteristics of MR fluid lies in its abilities to reversibly, repeatedly and instantly change from a free flowing liquid to a semi-solid state when exposed to a magnetic field. The electric power required to drive the MR devices can be easily provided by a battery. Possessing such unique properties, MR fluid based devices, such as MR damper, have become promising candidates in the semi-active control for civil structure applications. However, most of the published research has focused on application of MR dampers instead of exploring other type of MR devices. In addition, MR based devices exhibit complex nonlinear hysteresis behaviour and thus making their modelling a challenging task.In this paper, a novel MR fluid based device, namely MR pin joint, is proposed as a smart structural member in development of an intelligent civil structure that can suppress unwanted vibrations to ensure safety and serviceability of the structure. After design and fabrication, experiments have been conducted to characterise dynamic behaviours of the new device under different harmonic excitations with various input currents. Response time of the MR pin joint is compared when the MR pin joint is driven under different applied currents and moving speeds. Test data shows that the MR pin joint possesses a unique behaviour in the moment-angular velocity plot. A hyperbolic hysteresis model is proposed to model such unique behaviour. The investigation presented in the paper explores dynamic performance of MR pin joint. Finally, a parametric model is developed following the investigation on the correlation of coefficients in the proposed model with the loading conditions and applied currents.

A safety and arming (S&A) device keeps the fuze of a projectile unarmed during shipping, handling and storage, while arming the firing section at a proper time by sensing external conditions such as pressure, position, etc. With the increasing need for smaller S&A devices, a miniature design with a compact configuration and high reliability is in demand. This paper proposes a miniaturized timing trigger as the S&A device for a spinning projectile by utilizing the 'locking' and 'unlocking' properties of magnetorheological (MR) grease with/without the presence of a magnetic field. First, the design and arming mechanism of the timing trigger are introduced, in which the MR grease is locked by a magnetic field generated by two permanent magnets (PMs). Under sufficient firing acceleration, the PMs disengage to unlock the contraction flow of the MR grease, which enables its triggering function. A theoretical analysis was conducted to interpolate the delay time against the geometry of the device, the shear/extensional characteristics of MR grease and the spinning rate of a projectile. A series of tests have been conducted to measure the delay times by tuning the physical parameters, including particle concentration, spinning rate and orifice diameter etc. The experimental results showed that this theoretical model is capable of calculating well the delay time of a MR grease timing trigger.

Magnetorheological elastomer (MRE) isolator has been proved as a promising semi-active control device for structural vibration control. For its engineering application, developing an accurate and robust model is definitely necessary and also a challenging task. Most of the present models, belonging to parametric models, need to identify various model parameters and sometimes are not capable of perfectly capturing the unique characteristics of the device. In this work, a novel nonparametric model is proposed to characterize the inherent dynamics of the MRE isolator with the features of hysteresis and nonlinearity. Initially, dynamic tests are conducted to evaluate the performance of the isolator under various loading conditions, including harmonic, random, and seismic excitations. Then, on the basis of the captured experimental results, a hybrid learning method is designed to forecast the nonlinear responses of the device with known external inputs. In this method, a type of single hidden layer feed-forward network, called extreme learning machine (ELM), is developed to forecast the nonlinear responses (shear force) of the device with captured velocity, displacement, and current level. To obtain optimal performance of the developed model, an improved binary-coded discrete cat swarm optimization (BCDCSO) method is adopted to select optimal inputs and neuron number in the hidden layer for the network development. The performance of the proposed method is verified through the comparison between experimental results and model predictions. Due to the noise influence in the practical condition, the robustness of the proposed method is also validated via adding noise disturbance into the supplying currents. The results show that the proposed method outperforms the standard ELM in terms of characterization of the MRE isolator, even though the captured responses are polluted with external measurement noises.

© 2018 IOP Publishing Ltd. In this article, the effect of elevated temperature on the rheological properties of grease-based magnetorheological fluids (G-MRFs) with the focus on long-term storage lifetime has been investigated. These G-MRF samples were subjected to accelerated heat aging process for the estimation of thermal stability and useful lifetime prediction. The well-known Arrhenius-Weibull relationship with a modified Powell-Beal conjugate gradient (CGP) algorithm was employed to model the 'life in service' for the achievement of possible life distribution at different temperature conditions. By defining the failure criteria of G-MRF samples as a maximum reduction of either viscosity or shear stress by more than 10%, the underlying degradation mechanism was revealed through Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) analysis. Based on the statistical inference from accelerated life test (ALT), the life expectancy of G-MRF under nominal operating temperature is estimated to be 15.2 years, which outpaces the capability of most industrial applications. Experimental results showed that the performance of shear stress is more likely to degrade under long-term treatment of high temperature in comparison with low temperature. Thus, it is suggested to store the G-MRF at relatively low temperatures for longevity extension and reliability improvement.

Hostile dynamic loadings such as severe wind storms, earthquakes, and sudden impacts can cause severe damage to many civil engineering structures. An intelligent structural system equipped with smart structural members that are controllable in real-time is an effective solution to structural damage and failure during such situations. Civil intelligent structures with controllable properties to adapt to any changes due to dynamic loadings can lead to effective protection of structures and their occupants. In this paper, design and testing of a semi-active magnetorheological (MR) pin joint, in which the moment resistance can be controlled in real-time by altering the magnetic field, is reported with the view of using it as a potential candidate for smart members in the development of intelligent structures. Design of prototype smart pin joints includes theoretical analysis related to the radius of the rotary plate, the property of MR fluids and the gap between the rotary plate and the casing based on the requirements of the dynamics of MR pin joints. FEM analysis was deployed to study the distribution of the magnetic field along the gap. It is found, from the theoretical analysis and experimental verification, that the MR pin joint with a diameter of 180 mm can produce a torque of up to 30 Nm, which meets requirements for semi-active members in a multi-storey prototype building model in the next stage of research and development. © Higher Education Press and Springer-Verlag 2009.

© 2015 IEEE. A novel hybrid model is proposed in this paper to describe the highly-nonlinear hysteretic relationship between the torque and angular velocity in a magnetorheological pin joint (MRP). The MRP's hysteresis loop is modelled by a mixture of hyperbolic and Gaussian functions using the curve fitting technique, resulting in a significant reduction of the model parameters. To identify the model parameters, an immune particle swarm optimization (IPSO) algorithm is employed using torque-angular displacement/velocity experimental data recorded under various loading conditions. To demonstrate the accuracy of the proposed model and the effectiveness of parameter identification process, characterization test data of the smart pin torque and angular velocity are utilized for comparison.

© 2015, Springer Science+Business Media Dordrecht. The recently-developed magnetorheological elastomer (MRE) base isolator can provide an instant change in the shear modulus and damping property under applied magnetic field, which makes it as an ideal device for the semi-active control in buildings and bridges. Previous studies show that this new device is featured with its nonlinear and hysteretic responses, and it is necessary to sufficiently understand its behaviour when adopting this device in control system. Although there are several models presented to predict the hysteresis of MRE base isolator, they are always suffered from some application limitations, e.g. high computation demand or complex model. To better interpret this complicated feature of the device, this work presents an improved LuGre friction model, which has been successfully used in modelling other magnetorheological device i.e. MR damper. In addition, an improved fruit fly optimization algorithm (IFFOA) is also proposed to identify the model parameters. In the improved algorithm, a transfer factor based on a self-adaptive step is added together with a three-dimensional searching space. This improvement can enhance the convergence rate of the algorithm and avoid the local optimum. Furthermore, to reduce the complexity of the model, the local and global parameter sensitivity analyses are conducted for model simplification. Eventually, the experimental measurements of device displacement, velocity and shear force are used to evaluate the performance of the proposed model and IFFOA.

© 2015 IOP Publishing Ltd. Due to its inherent hysteretic characteristics, the main challenge for the application of a magnetorheological elastomer- (MRE) based isolator is the exploitation of the accurate model, which could fully describe its unique behaviour. This paper proposes a nonparametric model for a MRE-based isolator based on support vector regression (SVR). The trained identification model is to forecast the shear force of the MRE-based isolator online; thus, the dynamic response from the MRE-based isolator can be well captured. In order to improve the forecast capacity of the model, a type of improved particle swarm optimization (IPSO) is employed to optimize the parameters in SVR. Eventually, the trained model is applied to the MRE-based isolator modelling with testing data. The results indicate that the proposed hybrid model has a better generalization capacity and better recognition accuracy than other conventional models, and it is an effective and suitable approach for forecasting the behaviours of a MRE-based isolator.

Copyright © 2015 by ASME. This paper presents a recent research advance on the development of a novel adaptive seismic isolation system to be used in seismic protection of civil structures. A highly adjustable laminated magnetorheological elastomer (MRE) base isolator was developed and experimental results show that the prototypical MRE base isolator provides increase in lateral stiffness up to 1630%. To facilitate the structural control development using such adaptive MRE base isolator, an analytical model was developed to simulate its behaviors. Comparison between the analytical model and experimental data proves the effectiveness of such model in reproducing the behavior of MRE base isolator.

© SAGE Publications. This article presents a novel model to describe the nonlinear relationships between shear force and displacement/velocity in a magnetorheological elastomer base isolator. The proposed model, containing a strain stiffening element, is able to portray the distinct dynamic behaviors of magnetorheological elastomer base isolator. To identify the model parameters, an enhanced particle swarm optimization is used on force-displacement/velocity data sampled under different loading conditions. In this algorithm, a self-adaptive inertia weight replaces the general linear weight, enhancing the convergence rate of iteration process. Besides, the mutation operator in genetic algorithm is adopted for finding global optimum. Testing data of the device displacement, velocity and force from magnetorheological elastomer base isolator are utilized to validate the proposed model and corresponding parameter identification algorithm.

The magnetorheological (MR) shock absorber is one of the most promising new devices for vibration reduction. Many investigations have been carried out on low velocity and frequency applications of MR devices. The use of the MR shock absorber under impact load is of great interest. The now widely used MR damper models, such as the Bingham model, cannot explain sufficiently the shear thinning behavior under impact loads. However, the Herschel–Bulkley model can be used to explain the same. The main purpose of this study is to analyze the behavior of the MR shock absorber under impact load and to verify the analytical conclusions and experiments. First, some dynamic simulations on the MR shock absorber under impact loads in Matlab and Simulink are carried out. The model describes the dynamic characteristics especially the shear thinning behavior of the shock absorber, based on this model, then analyzes the variations of piston acceleration and back cavity pressure of MR shock absorber at both same and different flow indices. A test rig is developed to test the characteristics of the long-stroke MR shock absorber under impact loads. Comparisons between the simulation and the test results are made to validate our conclusions. The results indicate that the peak acceleration value of the piston rod and the pressure of the back cavity are decided by the peak value and the duration of the impact force. The peak value of the acceleration and the cavity pressure cannot be changed, but the transitional time of the acceleration of the piston and the pressure of the back cavity of MR shock absorber can be controlled by changing the applied current in the electromagnetic coil. MR shock absorbers will be the most promising shock reduction device under an impact environment.

© 2014 IOP Publishing Ltd. During the last few decades, magnetorheological (MR) elastomers have attracted a significant amount of attention for their enormous potential in engineering applications. Because they are a solid counterpart to MR fluids, MR elastomers exhibit a unique field-dependent material property when exposed to a magnetic field, and they overcome major issues faced in magnetorheological fluids, e.g. the deposition of iron particles, sealing problems and environmental contamination. Such advantages offer great potential for designing intelligent devices to be used in various engineering fields, especially in fields that involve vibration reduction and isolation. This paper presents a state of the art review on the recent progress of MR elastomer technology, with special emphasis on the research and development of MR elastomer devices and their applications. To keep the integrity of the knowledge, this review includes a brief introduction of MR elastomer materials and follows with a discussion of critical issues involved in designing magnetorheological elastomer devices, i.e. operation modes, coil placements and principle fundamentals. A comprehensive review has been presented on the research and development of MR elastomer devices, including vibration absorbers, vibration isolators, base isolators, sensing devices, and so on. A summary of the research on the modeling mechanical behavior for both the material and the devices is presented. Finally, the challenges and the potential facing magnetorheological elastomer technology are discussed, and suggestions have been made based on the authors' knowledge and experience.

Time delay is a challenge issue faced by the real-time control application of the magnetorheological (MR) devices. Not to deal with it properly may jeopardize the effectiveness of the control, even lead to instability of the control system or catastrophic failure. This paper proposes a dual-loop adaptive control to address the response time delay associated with MR devices. In the proposed dual-loop control, the inner loop is designed to compensate the time delay of MR device induced by the PWM current driver. While the outer loop control can be any structural control algorithm with aims to reducing structural responses of a building during extreme loadings. Here an adaptive control strategy is adopted. To verify the proposed dual-loop control, a smart base isolation system employing magnetorheological elastomer base isolators is used as an example to illustrate the control effect. Numerical study is then conducted using a 5 -storey shear building model equipped with smart base isolation system. The result shows that with the implementation of the inner loop, the control current can instantly follow the control command which reduce the possibility of instability caused by the time delay. Comparative studies are conducted between three control strategies, i.e. dual-loop control, Lyapunov's direct method based control and optimal passive base isolation control. The results of the study have demonstrated that the proposed dual-loop control strategy can achieve much better performance than the other two control strategies.

© 2017 IOP Publishing Ltd. This paper reports an investigation on a semi-active/passive integrated vibration isolator utilizing a magnetorheological elastomer (MRE) and spring. To overcome the main shortcoming of passive isolation systems, i.e. lack of adaptability, the semi-active/passive integrated isolator (SAPII) based on an MRE and spring is designed and prototyped. The magnetic circuit is optimized by finite element analysis to fully unlock the unique features of the MRE. The dynamic response characteristic of the SAPII is experimentally investigated under a sweep frequency test. A dynamic model of the SAPII vibration isolation system is established on the basis of the Kelvin model. The model parameters, such as equivalent stiffness and equivalent damping, are identified from experimental data. An ON-OFF control law based on the minimal displacement transmissibility is designed for isolation control of the sinusoid excitation. Two control laws, i.e. ON-OFF control and fuzzy logic control, are designed for vibration isolation of random excitation. Finally, the effectiveness of these control laws is verified by numerical simulation and experiment.

© 2017 IOP Publishing Ltd. This paper presents research on the phenomenological model of an adaptive base isolator. The adaptive base isolator is made of field-dependent magnetorheological elastomer (MRE) which can alter its physical property under application of magnetic field. Experimental testing demonstrated that the developed MRE base isolator possesses an amazing ability to vary its stiffness under applied magnetic field. However, several challenges have been encountered when it comes modeling such novel device. For example, under a large deformation, the MRE base isolator exhibits a clear strain stiffening effect and this behavior escalates with the increasing of applied current. In addition, the MRE base isolator has also shown typical rate-dependent behavior. Following a review on mechanical models for viscos-elastic rubber devices, a novel rate-dependent model is proposed in this paper to capture the behavior of the new MRE base isolator. To develop a generalized model, the proposed model was evaluated using its performance under random displacement input and a seismic input. It shows that the proposed rate-dependent model can successfully describe the complex behavior of the device.

Introduction Typical aura without headache (TAWH), which has been rarely reported both at home and abroad, is a rare type of migraine with aura. Case presentation This is a report on a 64-year-old Chinese migraineur who has had recurrent typical visual aura without headache attacks for more than 30 years, and has been misdiagnosed as having had transient ischemic attacks (TIA) many times. He mainly experienced episodes of ‘homonymous blurred vision’ or photopsia, which presented as different shapes located at the side or above his visual field, for example, patchy, cord-like, zigzag, curtain-like or irregular shapes. The shape was inconsistent during each attack, however, the color was mainly gray or light blue. The visual symptoms gradually disappeared in about 30 minutes. Our patient has never suffered a headache attack during or after the visual aura. Normal results were observed in his neurological and eye examinations, complete blood test, electroencephalogram and neuroimaging examination. Conclusions TAWH is an uncommon phenomenon of migraine. Migraine with visual aura mainly presents positive and dynamic symptoms. It has a benign course and can be diagnosed after exclusion of other organic diseases such as TIA and epilepsy.

An intelligent civil structure offers ultimate protection to its structure, contents and occupants in terms of safety and functionality against undesired dynamic loadings and structural deficiency. In this paper, the concept of the future intelligent civil structure featuring self-adaptive, selfprognostic, self-sensing, self-powering and self-repairing abilities, is proposed. A decade research efforts from Centre for Built Infrastructure Research, University of Technology Sydney, towards the development and concept proof of such intelligent structure is reviewed.

The coping strategy of a CANON (completely autotrophic nitrogen removal over nitrite) reactor working at room temperature was investigated using response surface methodology. The total nitrogen (TN) removal efficiency was taken as a dependent variable. The temperature ( X ), dissolved oxygen (DO) concentration ( Y ), and influent nitrogen loading rate ( Z ) were taken as independent variables. Results showed that the relation of these three independent variables can be described by the TN removal efficiency expressed as −5.03 + 1.51 X + 45.16 Y + 30.13 Z + 0.26 XY + 1.84 XZ − 0.04 X 2 − 9.06 Y 2 − 99.00 Z 2. The analysis of variance proved that the equation is applicable. The response surface demonstrated that the temperature significantly interacts with the DO concentration and influent N loading rate. A coping strategy for the CANON reactor working at room temperature is thus proposed: altering the DO concentration and the N loading rate to counterbalance the impact of low temperature. The verification test proved the strategy is viable. The TN removal efficiency was 91.3% when the reactor was operated under a temperature of 35.0 °C, a DO of 3.0 mg/L, and a N loading rate of 0.70 kgN/(m³ d). When the temperature dropped from 35.0 to 19.2 °C, the TN removal efficiency was kept at 88.7% by regulating the influent N loading rate from 0.7 kgN/(m³ d) to 0.35 kgN/(m³ d) and the DO concentration from 3.0 to 2.6 mg/L.

Magnetorheological (MR) pin joint is a novel device in which its joint moment resistance can be controlled in real-time by altering the applied magnetic field. The smart pin joint is intended to be used as a controllable connector between the columns and beams of a civil structure to instantaneously shift the structural natural frequencies in order to avoid resonance and therefore to reduce unwanted vibrations and hence prevent structural damage. As an intrinsically nonlinear device, modelling of this MR fluid based device is a challenging task and makes the design of a suitable control algorithm a cumbersome situation. Aimed at its application in civil structure, the main purpose of this paper is to test and characterise the hysteretic behaviour of MR pin joint. A test scheme is designed to obtain the dynamic performance of MR pin joint in the dominant earthquake frequency range. Some unique phenomena different from those of MR damper are observed through the experimental testing. A computationally-efficient model is proposed by introducing a hyperbolic element to accurately reproduce its dynamic behaviour and to further facilitate the design of a suitable control algorithm. Comprehensive investigations on the model accuracy and dependences of the proposed model on loading condition (frequency and amplitude) and input current level are reported in the last section of this paper. © 2014 Higher Education Press and Springer-Verlag Berlin Heidelberg.

This paper focuses on the development and experimental testing of a potential clean energy source for powering the remote equipment used in transportation infrastructure. Traditional power sources (i.e., power cables and batteries) are excessively expensive or infeasible in this type of application. A compression-based roadway energy harvester has been developed that can be embedded into pavement to scavenge electrical energy from traffic-induced vibrations. The proposed roadway harvester employs a group of piezoelectric harvesting units to convert traffic-induced vibrations into electrical energy, and each single harvesting unit contains three piezoelectric multilayer stacks. According to the linear theory of piezoelasticity, a two-degree-of-freedom electromechanical model of the piezoelectric harvesting unit was developed to characterize its performance in generating electrical energy under external excitations. Experimental testing in the laboratory was conducted to investigate the output power properties of the harvesting unit and shows good agreement with the theoretical analysis. Based on the testing results of the harvesting unit, the capability of the proposed roadway harvester has been theoretically evaluated and demonstrated that it has the ability to generate sufficient energy for driving common electrical equipment used in transportation infrastructure. © 2014 AIP Publishing LLC.

The nozzle/diffuser flow with different Reynolds number ranges and conical angles is analyzed first. It is found that the flow coefficients of nozzle/diffuser ξn and ξd vary with angle with different trends for large (> 105) and small (

Magnetorheological elastomer (MRE) is known for its field-sensitive shear modulus and damping property when it is exposed to a magnetic field. It has a great potential for the development of vibration reduction devices. Many research, mostly in mechanical engineering, have been focused on different kinds of vibration absorbers and vibration isolators, however few research addresses its potential in base isolation system in civil engineering application. The objective of this paper is to pilot the design and experimental testing of a novel device, an adaptive MRE base isolator, for the development of smart base isolation system. A large-scale design of the novel device with unique laminated structure of steel and MR elastomer layers is adopted. Detailed procedures on designing such adaptive base isolator are introduced. An innovative design on the magnetic circuit, with aim to provide strong and uniform magnetic field to the multi-layer MRES, is proposed to incorporate into the device design. Experimental investigation is conducted to examine its behavior under various cycling loadings when it is applied with different current inputs. Experimental results indicated that the force increase and the stiffness increase of the novel device are about 45% and 37%, respectively. To conclude, the MR elastomer base isolator will be a promising candidate to facilitate the development of adaptive base isolation system for civil structures. © 2013 IEEE.

This paper presents a novel linear tubular permanent magnet (PM) energy harvester to scavenge energy from ambient vibrations. The proposed linear PM energy harvester consists of a mover attached with PMs and a slotted stator with build-in two-phase electromagnetic coils to induce the electromagnetic induction for converting vibrations into useful electrical energy. The magnetic circuit model of the PM harvester is built to analyze the parameters about scavenging energy and used to optimize the non-dimensional geometry factors and the structural parameters in order to maximize harvested energy under given vibration and space conditions. To confirm the design, dynamic FE simulations were conducted and compared with the analytical results. Simulation results indicate that the proposed PM harvester is able to scavenge about 100 W DC power when the RMS of vibration velocity equals to 0.4 m/s. Also, the harvested power increases as the vibration velocity increasing. © 2013 IEEE.