Hysteresis

AbstractExperimental results to determine the moment-resisting capacity of wood portal frame corner joints are presented in this paper. Two types of corner joints (standard and MIDPLY) were tested with different configurations. An L-shaped corner joint including a narrow braced wall segment and header was used as a test specimen. A total of 37 corner joints were tested. Test results showed that the installation of metal strap or the adding of exterior oriented strand board (OSB) sheathing, while using high-density wood product (LVL, LSL) as header increased the moment-resisting capacity of corner joints. Furthermore, the MIDPLY corner joint had higher moment capacity than the standard corner joint. The moment-carrying capacity of corner joints could be further increased by applying fiber-reinforced polymer (FRP) on top of exterior OSB sheathing. A detailed finite element (FE) model of a corner joint is presented. The FE model predictions correlated well with the experimental results.

Streszczenie W pracy przedstawiono sposób otrzymywania i wyniki pomiarów wáaĞciwoĞci fizycznych ceramiki (Pb1-xLax)(Zr1-yTiy) O3, gdzie x= 0, 03 lub 0, 06, y= 0, 9 (PLZT) oraz (Pb1-xLax)[(Zr1-yTiy) 1-zSnz] O3, gdzie x= 0, 04, y= 0, 9, z= 0, 02, 0, 04, 0, 06, 0, 08 (PLZTS). Materiaáy te naleĪą do roztworów staáych tlenowooktaedrycznych o strukturze typu perowskitu. Badane materiaáy zostaáy wykonane przy uĪyciu klasycznej technologii ceramicznej z wykorzystaniem tlenków. Przedstawione zostaáy wyniki badaĔ ...

A simulation based comparative study of the polarization hysteresis of the ferroelectric capacitor using various ferroelectric models is presented. A 2-dimensional finite element device-level model was implemented using SILVACO's ATLAS device simulator to generate the polarization hysteresis characteristics for Au/Poly(vinylidene fluoride-trifluoroethylene)/Au metal-insulator-metal (MIM) device. Landau free energy expression for electric field in terms of polarization is also implemented in the MATLAB to produce the polarization hysteresis curve of polycrystalline ferroelectrics. The main drawback of these models was their inability to predict polarization saturation at the same electric field limits for which the experimental device was saturating. A new model for ferroelectric hysteresis based on curve fitting algorithm is derived that forces the polarization to be saturated at desired electric field. The MATLAB simulation of this model and the experimental hysteresis is compared which shows an excellent level of agreement.

The water vapor sorption behavior of a range of natural fibers (jute, flax, coir, cotton, hemp, Sitka spruce) has been studied. The data were analyzed using the Hailwood Horrobin model for isotherm fitting and determination of monolayer moisture content. The Hailwood Horrobin model was found to provide good fits to the experimental data. The extent of hysteresis exhibited between the adsorption and desorption isotherms was dependent on fiber type studied and was larger with high lignin compared with low lignin content fibers. The area bounded by the hysteresis loop decreased as the isotherms were performed at progressively higher temperatures. This behavior is consistent with sorption interactions occurring with a glassy solid below the glass transition temperature. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Zinc substitution is proposed as an efficient way to improve the performance of the ferrite. In this work, Zinc doped cobalt ferrite with the generic formula CoZnxFe2-xO4, with x = 0.0, 0.1, 0.3 and 0.4 were prepared by conventional ceramic technique, sintered at 1000 ο C for 4 hours in air. The effect of zinc concentration on the initial permeability, Curie temperature, saturation magnetization, magnetic moment, coercivity and magnetic susceptibility was investigated. Contrary to most of the work in this subject, here Co is maintained fixed and Fe is progressively varied along with Zn. Curie temperature is found to increase initially up to 459 C for Zn content of x = 0.1 and then decreased to 148C for further increase of Zn content (x = 0.4). Effect of Zn on the frequency dependent initial permeability, loss factor and relative quality factor was studied. The maximum value of saturation magnetization (51.37emu/gm) was found for the sample x = 0.1 and then decreases with the increas...

The aim of equipping a wireless network with a mobile relay node is to support broadband wireless communications for vehicular users and their devices. The high mobility of vehicular users, possibly at a very high velocity in the area in which two cells overlap, could cause the network to suffer from a reduced handover success rate and, hence, increased radio link failure. The combined impact of these problems is service interruptions to vehicular users. Thus, the handover schemes are crucial in solving these problems. In this work, we first present the adaptive handover hysteresis scheme for the wireless network with mobile relay nodes in the high-speed train scenario. Specifically, our proposed adaptive hysteresis scheme is based on the velocity of the train. Second, the handover call dropping probability is reduced by introducing a modified call admission control scheme to support radio resource reservation for handover calls that prioritizes handover calls of mobile relay over the other calls. The proposed solution in which adaptive parameter is combined with call admission control is evaluated by system level simulation. Our simulation results illustrate an increased handover success rate and reduced radio link failures.

This research article presents the method to control the DC voltage of the boost converter by using a proportional-integral (PI) controller. With AC voltage from a wind turbine generator, converting to DC voltage level by rectifier, this DC voltage controlled by PI controller is to control boost converter that sends DC links to the inverter which converting alternating current voltage to direct current voltage through three-phase load and to the grid-connected system. For switching the IGBTs in the inverter, the PWM signal, on the hysteresis current control, is controlled by the signal from the detected reference voltage based on the grid-connected system and the voltage from a wind turbine generator. The tests made the comparison of results from the simulation with the MATLAB/Simulink program and result from the hardware on the prototype. The power quality results, such as harmonic, power factor, are in acceptable ranges.

In this exposition we hope to dispel some common misconceptions about the nature of hysteresis elements are associated with parasitic dynamics in the circuit and therefore should not be considered part of the static characteristics.We examine the Schmitt trigger ciruit, which exhibits hysteresis in its transfer characteristic, and study a neuraltype pulse oscillator, one of a class of oscillators which relies for its operation on diriving point hysteresis. We illustrate the concepts of DC characteristics, the dynamic route, the jump phenomenon and parasitic dynamics. We show how a clear understanding of these ciruit theoretic principles leads to better analysis and synthesis methods for hysteretic cirucits.

This paper presents a low voltage adjustable CMOS Schmitt trigger using dynamic threshold MOS (DTMOS). Cross-coupled inverter with body control is employed to speed up the switching process, and control the intensity of the feedback. The proposed Schmitt trigger has been designed using 0.18 μm 0.4 V CMOS technology and analyzed using PSPICE with BSIM3V3 device models. The simulation results show rail-to-rail operation and independently adjustable switching voltages for both low-to-high (VT(LH)) and high-to-low (VT(HL)) as high as 15% of the supply voltage. The power dissipation is 0.13 μW.

Piezoelectric actuators are popularly applied as actuators in high precision systems due to their small displacement resolution, fast response and simple construction. However, the hysteresis nonlinear behavior limits the dynamic modeling and tracking control of piezoelectric actuators. This thesis studies a dynamic model of a moving stage driven by piezoelectric stack actuator. The Bouc-Wen model is introduced and analyzed to express the nonlinear hysteresis term of the piezoelectric stack actuator, where the values of the parameters of the model have been taken from a previous work. The simulated results using MATLAB/Simulink demonstrate the existence of the hysteresis phenomenon between the input voltage and the output displacement of the piezoelectric stack actuator, and validate the correctness of the model. Moreover, a Luenberger observer is designed to estimate the hysteresis nonlinearity of the system, and then combined with the voltage input signal to form a Luenberger-based feedforward controller to control the displacement of the system. Furthermore, a Proportional-Integral-Derivative (PID) feedback controller is integrated with the feedforward controller to achieve more accurate output displacement, where the gains of the PID controller are optimized using Particle Swarm Optimization. Several performance index formulas have been studied to get the best solution of the PID’s gains. An Integral Time Squared Error plus Absolute Error performance index formula has been proposed to achieve zero overshoot and steady-state error. The simulated results accomplished using MATLAB/Simulink show the ability of the designed controllers to vastly reduce the amount of error of the output displacement and the response time of the system.

Simulations of flow over a 2D axisymmetric cylinder was performed at different Reynolds number to obtain values of drag coefficient (CD) and lift coefficient (CL) which were then validated with velocity and pressure contour plots. Further validation was achieved with obtaining plots of pressure coefficient (CP) at these different Reynold number and then compared with the data from the literature. Simulation of flow over a non-rotating NACA 0012 airfoil was performed at different Reynold's number and angle of attacks (AOA) and validated by comparison of values of CL and CP with the chosen literature and, for simulation of flow over a rotating NACA 0012 airfoil performed at varying angles of attacks, the results was validated with plots of CL with varying AOA to achieve an understanding of the effects of stall accompanied with hysteresis on the values of CD and CL when the airfoil is rotated within a range of AOA incident to the incoming flow.

A new identification method that determines the parameters of Bouc-Wen hysteretic systems is presented. It is based on a hybrid evolutionary algorithm which utilizes selected stochastic operators, heuristics and problem-specific information. The proposed method exhibits efficiency, robustness and insensitivity to noise-corrupted data, while it identifies accurately both hysteretic and viscous damping based on suitable experiments. Its performance is investigated with respect to the information content of the input-output data. The scheme is verified by a hysteretic system representing a full-scale steel cantilever beam which is identified successfully. A series of parametric studies are also conducted that illustrate the inner workings of the proposed method, suggesting appropriate values for the controlling parameters.

Un enjeu majeur de l’industrie aeronautique de demain est de concevoir et developper un avion « plus » electrique. En effet, sur un avion de ligne, les principaux systemes utilisent des types d'energies differents tels que l'energie hydraulique ou pneumatique. La tendance actuelle est a la conversion de ces systemes a l'energie electrique car elle presente de nombreux avantages et permettrait des economies de masse, d’energie, et de couts de maintenance. Avec l’augmentation croissante des systemes electriques dans l’avion se posent par consequent des problemes d’interferences et de compatibilite electromagnetique entre ces differents dispositifs. Par ailleurs ces systemes electriques sont soumis a des conditions de travail tres severes, notamment des temperatures extremes. Dans le cadre du projet FEMINA (Filtrage Electromagnetiques et Materiaux pour l’INtegration en Aeronautique), l’objectif de notre equipe etait d’etudier un filtre electrique soumis a des conditions de ...