Characteristic Transfer Function Research Articles

Inductive Superconducting Quantum Interference Proximity Transistor: The L-SQUIPT

The design for an inductive superconducting quantum interference proximity transistor with enhanced performance, the L-SQUIPT, is presented and analyzed. The interferometer is based on a double-loop structure, where each ring comprises a superconductor-normal metal-superconductor mesoscopic Josephson weak-link and the read-out electrode is implemented in the form of a superconducting tunnel probe. Our design allows both to improve the coupling of the transistor to the external magnetic field and to increase the characteristic magnetic flux transfer functions, thereby leading to an improved ultrasensitive quantum limited magnetometer. The L-SQUIPT behavior is analyzed in both the dissipative and the dissipationless Josephson-like operation modes, in the dissipative or in the dissipationless Josephson-like operation mode in the latter case by exploiting both an inductive and a dispersive readout scheme. The improved performance makes the L-SQUIPT promising for magnetic field detection as well as for specific applications in quantum technology, where a responsive dispersive magnetometry at milliKelvin temperatures is required.

An experimental analysis of component contributions to shock absorption performance in third generation sport artificial turf

The increasing use of artificial turf across all levels of sports play has been hypothesized to contribute to an increase in athlete injuries. Current testing standards evaluate the shock absorbing performance of artificial turf surfaces through a single measure of acceleration after a drop test impact. However, these standards focus on the performance of the aggregate turf system, thereby neglecting the component-level contributions of the shock pad, carpet, and infill constituents. The purpose of this study was to explore a novel testing methodology that has the potential to isolate first-order and second-order contributions of components to total system performance. Various subsystems of the traditional, three layer artificial turf were treated as energy absorbing surfaces. A series of no-fatigue and fatigue tests were performed using a custom-built apparatus to characterize each energy absorbing surface at five different drop heights. During no-fatigue testing, it was found that the complete three-layer system outperformed all subsystems by mitigating resultant acceleration and force compared to the baseline. However, any energy absorbing subsystem that contained rubber infill outperformed any subsystem that included shock pad, the designated energy dissipating layer in third generation artificial turf. For fatigue testing, it was observed that energy absorbing surfaces began to deteriorate in as few as 20 impacts. In comparison to existing standards, the inclusion of a second data acquisition instrument yielded more accurate calculations of shock absorption. By capturing an input and output measurement during the impact, calculation of the surface’s characteristic transfer function is attainable and therefore, more information in gleaned from the impact test. Additional research is required to be able to deploy this testing methodology on-site, with fully installed artificial turf systems.

Signal Enhancement Method for Mechanical Fault Diagnosis in Flexible Drive-Train

Nowadays, mechanical fault detection techniques based on signals from motor drive are becoming popular. However, in electromechanical system with flexible drive-train, mechanical fault signature reflected in motor drive is suppressed by the transmission path. This signal attenuation reduces the effectiveness of fault detection. Therefore, research on the law of fault signature transmission from load to motor is necessary. In this article, a two-mass electromechanical system with a long shaft is concerned. First, the transmission path from load torque to electromagnetic torque is analyzed, and the concept of torque transmission efficiency is proposed. Then, the frequency characteristic method and transfer function method are presented to establish the signal transmission model. Finally, the model-based signal enhancement method is proposed to compensate the attenuation. Simulation and experimental results show that the proposed method can enhance the quality of fault signature transmission and improve the performance of fault classification.

Passive modelling of the electrodynamic loudspeaker: from the Thiele–Small model to nonlinear port-Hamiltonian systems

The electrodynamic loudspeaker couples mechanical, magnetic, electric and thermodynamic phenomena. The Thiele/Small (TS) model provides a low frequency approximation, combining passive linear (multiphysical or electric-equivalent) components. This is commonly used by manufacturers as a reference to specify basic parameters and characteristic transfer functions. This paper presents more refined nonlinear models of electric, magnetic and mechanical phenomena, for which fundamental properties such as passivity and causality are guaranteed. More precisely, multiphysical models of the driver are formulated in the core class of port-Hamiltonian systems (PHS), which satisfies a power balance decomposed into conservative, dissipative and source parts. First, the TS model is reformulated as a linear PHS. Then, refinements are introduced, step-by-step, benefiting from the component-based approach allowed by the PHS formalism. Guaranteed-passive simulations are proposed, based on a numerical scheme that preserves the power balance. Numerical experiments that qualitatively comply with measured behaviors available in the literature are presented throughout the paper.

Algorithm for Obtaining a Characteristic Polynom and Transfer Function of Dynamic Model of Drone “Swarm”

В данной статье рассматривается получение характеристического полинома динамической модели «роя» дронов. Разработанный алгоритм анализа топологических моделей позволяет получить характеристический полином и передаточную функцию системы в буквенно-численном виде методом присоединения по одной вершине. Алгоритм отличается от существующих применением более оптимального механизма построения деревьев и прадеревьев частей графа, позволившего сократить затраты времени и памяти. Формализованная информация о графе, включающая множество варьируемых параметров, и служит исходной информацией при построении характеристического полинома и передаточной функции системы. Основными элементами этой информации являются внутренние и внешние вершины. Описание частей графа с целью выявления замкнутых контуров доводим с помощью специально разработанного множества кортежей части, элементами которого являются нулевая вершина и вершины множества. Описан процесс образования множества кортежей, производимых по разработанным правилам. Представлены алгоритмы получения характеристического полинома части графа и характеристического полинома системы. Получение передаточной функции системы основано на применении рассмотренного алгоритма построения характеристического полинома для графа систем, в который введены дополнительные (структурные) дуги, указывающие пары входных и выходных узлов системы. Представление весов ребер и в виде параметрической функции ребра позволяет расширить возможности методов топологического анализа при автоматизированном проектировании динамических систем с изменяющимися во времени параметрами. Алгоритм дает возможность получать характеристический полином системы как явную функцию различных параметров, а не только тех, которые непосредственно являются коэффициентами дифференциальных уравнений системы. Это намного расширяет простор проектировщику в выборе параметров варьирования. Полученная модель учитывает изменчивость состава, структуры и уровня взаимодействия «роя». При изменении «роя» нет необходимости пересчитывать весь граф, а только изменившуюся часть. Алгоритм отличается от существующих применением более оптимального механизма построения деревьев и прадеревьев частей графа, позволившего сократить затраты времени и памяти

Accuracy of coded excitation methods for measuring the time of flight: Application to ultrasonic characterization of wood samples

Ultrasound computed tomography (USCT) using the transmission mode is a way to detect and assess the extent of decay in wood structures. The resolution of the ultrasonic image is closely related to the different anatomical features of wood. The complexity of the wave propagation process generates complex signals consisting of several wave packets with different signatures. Wave paths, depth dependencies, wave velocities or attenuations are often difficult to interpret. For this kind of assessment, the focus is generally on signal pre-processing. Several approaches have been used so far including filtering, spectrum analysis and a method involving deconvolution using a characteristic transfer function of the experimental device. However, all these approaches may be too sophisticated and/or unstable. The alternative methods proposed in this work are based on coded excitation, which makes it possible to process both local and general information available such as frequency and time parameters. Coded excitation is based on the filtering of the transmitted signal using a suitable electric input signal.The aim of the present study was to compare two coded-excitation methods, a chirp- and a wavelet-coded excitation method, to determine the time of flight of the ultrasonic wave, and to investigate the feasibility, the robustness and the precision of the measurement of geometrical and acoustical properties in laboratory conditions. To obtain control experimental data, the two methods were compared with the conventional ultrasonic pulse method.Experiments were conducted on a polyurethane resin sample and two samples of different wood species using two 500 kHz-transducers. The relative errors in the measurement of thickness compared with the results of caliper measurements ranged from 0.13% minimum for the wavelet-coded excitation method to 2.3% maximum for the chirp-coded excitation method. For the relative errors in the measurement of ultrasonic wave velocity, the coded excitation methods showed differences ranging from 0.24% minimum for the wavelet-coded excitation method to 2.62% maximum for the chirp-coded excitation method. Methods based on coded excitation algorithms thus enable accurate measurements of thickness and ultrasonic wave velocity in samples of wood species.

Non-invasive estimation of moisture content in tuff bricks by GPR

Measuring water content in buildings of historical value requires non-invasive techniques to avoid the damage that sample taking or probe insertion may cause to the investigated walls. With this aim, a stepped frequency ground penetrating radar (GPR) system was tested to assess its applicability in moisture measurements of porous masonry elements. The technique was tested on a real scale wall made with yellow Neapolitan tuff bricks, a material commonly found in historical buildings of Campania (Southern Italy). First, the antenna was calibrated to find its characteristic transfer functions. Then 64 GPR acquisitions, coupled with gravimetric measurements of the volumetric water content, were performed on the tuff wall in laboratory controlled conditions. A full inverse modelling of the GPR signal on tuff was used to retrieve dielectric permittivity and electrical conductivity of tuff at various water contents. By linking these characteristic electromagnetic parameters to the water content, the calibration relationships specific for yellow Neapolitan tuff are defined, which can be used for moisture measurements by GPR in real case studies. The experimental results lead to a robust identification of clearly defined monotonic relationships for dielectric permittivity and electrical conductivity. These are characterized by high values of the correlation coefficient, indicating that both parameters are potentially good proxies for water content of tuff. The results indicate that GPR represents a promising indirect technique for reliable measurements of water content in tuff walls and, potentially, in other porous building materials.

Dielectric backed conducting strips as inductive element in spatial band-pass filter design

In this paper a new method has been presented to design spatial band-pass filters consisting of dielectric backed conducting strips. This approach uses an equivalent circuit model in which determined inductive elements are spaced at intervals about half wavelength. To realize the proposed method, the inductive elements have been replaced by dielectric backed conducting strips located at intervals about half wavelength. Half wavelength transmission line sections act as resonators. In this manner the wideness and spacing of strips in each dielectric backed conducting strip, as well as the distance between them, is determined by fitting the characteristic (transfer function) of the proposed filter to that of a desired one obtained from an equivalent circuit model. To take the effect of higher order modes (evanescent mode), a coupled set of magnetic field integral equations is derived and formulated. Finally a set of linear matrix equations are solved using method of moments (MoM) and entire basis functions have been used resulting in rapid convergence. The usefulness of the proposed structure and its performance are verified by designing and simulating an equal ripple Chebyshev-type and a Butterworth-type spatial band-pass filter.

High-resolution pulsed electro-acoustic (HR PEA) measurement of space charge in outer space dielectric materials

The pulsed electro-acoustic (PEA) method is used for thirty years for measuring space charge distribution in dielectric materials [1]. However, this method was limited to at least 150 μm thick films characterization. For some applications, in spatial industry for example, 50 μm thick outer space dielectric materials must be analyzed. A high resolution optimized measurement system is discussed in this paper in order to expand performances and ranges of this method. To design it, a new pulse generator has been conceived and an optimized acoustic detector, key of the PEA method, has been realized and validated. The optimized High-Resolution PEA apparatus allows to obtain calibration signal with 50 μm thick dielectric materials that can be used to obtain the characteristic transfer function of the PEA system, essential step to use the data processing to find space charge distribution to characterize thinner dielectric materials.

Development of simple operation crane system for the real application

In each industry, the weight of the transportation work and quantity of the load has increased. Thus, now the crane equipment is introduced than ever. For overhead crane used in factories and warehouses, efficient operation which suppresses the swaying of the suspended load during transport is strongly demanded. In particular, it is necessary to suppress the initial shaking or disturbance due to the shift of the center of gravity and the hanging point position at the time of raising the suspended load. Therefore, we need to develop the simple operation crane system that enables the operation of the same level as the person skilled in the crane operation in order to improve the safety and efficiency. The author have investigated the control using Dual Model Matching method based on characteristic transfer function matrix to a configuration of the controller. By implementing feedback control on an actual overhead crane in practical use, the efficacy and operability of the system and the method were discussed. The purpose of this study, by developing the simple operation crane system that allows the same operation as the skilled operator, is to improve the safety and efficiency of the crane operation.

Conceptual rainfall-runoff model with a two-parameter, infinite characteristic time transfer function

A two-parameter transfer function with an infinite characteristic time is proposed for conceptual rainfall-runoff models. The large time behaviour of the unit response is an inverse power function of time. The infinite characteristic time allows long term memory effects to be accounted for. Such effects are observed in mountainous and karst catchments. The governing equation of the model is a fractional differential equation in the limit of long times. Although linear, the proposed transfer function yields discharge signals that can usually be obtained only using non-linear models. The model is applied successfully to two catchments, the Dud Koshi mountainous catchment in the Himalayas and the Durzon karst catchment in France. It compares favourably to the linear, non-linear single reservoir models and to the GR4J model. With a single reservoir and a single transfer function, the model is capable of reproducing hysteretic behaviours identied as typical of long term memory effects. Computational efficiency is enhanced by approximating the infinite characteristic time transfer function with a sum of simpler, exponential transfer functions. This amounts to partitioning the reservoir into several linear subreservoirs, the output discharges of which are easy to compute. An efficient partitioning strategy is presented to facilitate the practical implementation of the model.

Mass and Stiffness Impact on the Middle Ear and the Cochlear Partition.

Mass and stiffness affect on the peculiar characteristics of transmission of the middle ear and the distinctive behavior of the cochlear mechanics. Applying the principle of the mass and stiffness, the band-pass characteristic transfer function of the middle ear has been explained. The greatest transfer function of the middle ear, approximately 24-29 dB, is observed at 1-2 kHz in both cat and human species. However, at lower frequencies, the transfer function was disturbed by the stiffness of the middle ear primarily due to middle ear cavity. At higher frequencies, the transfer function was disturbed by the stiffness of the middle ear primarily due to middle ear bones. Several examples, such as an acoustic reflex, otitis media, and otosclerosis are discussed. For understanding the traveling wave of the basilar membrane, different place tuning at certain stimulus frequencies, contrastingly shaped basilar membrane to the cochlear duct, and the structural and physical characteristics of the whole cochlear partition were reviewed in terms of changing width, mass, and stiffness from the base to apex. Being about ten times wider, more massive, and one hundredfold stiffer at the base than the apex, the nature of the cochlear partition to absorb high-frequency energy changes in fluid pressure declines toward the apex. Consequently, at the base of the cochlea, high frequencies stimuli are decoded while low frequencies stimuli are decoded at the apex of the cochlea. Due to these characteristics of the cochlear partition, the direction of the traveling wave was also proved to be in the fashion of base-to-apex always.

On the formation of noise-like pulses in fiber ring cavity configurations

We give an overview of the current status of fiber-based noise-like pulse (NLP) research conducted over the past decade, together with presenting the newly conducted, systematic study on their temporal, spectral, and coherence characteristics in nonlinear polarization rotation (NPR)-based erbium-doped fiber ring cavity configurations. Firstly, our study includes experimental investigations on the characteristic features of NLPs both in the net anomalous dispersion regime and in the net normal dispersion regime, in comparison with coherent optical pulses that can alternatively be obtained from the same cavity configurations, i.e., with the conventional and dissipative solitons. Secondly, our study includes numerical simulations on the formation of NLPs, utilizing a simplified, scalar-field model based on the characteristic transfer function of the NPR mechanism in conjunction with the split-step Fourier algorithm, which offer a great help in exploring the interrelationship between the NLP formation and various cavity parameters, and eventually present good agreement with the experimental results. We stress that if the cavity operates with excessively high gain, i.e., higher than the levels just required for generating coherent mode-locked pulses, i.e., conventional solitons and dissipative solitons, it may trigger NLPs, depending on the characteristic transfer function of the NPR mechanism induced in the cavity. In particular, the NPR transfer function is characterized by the critical saturation power and the linear loss ratio. Finally, we also report on the applications of the fiber-based NLP sources, including supercontinuum generation in a master-oscillator power amplifier configuration seeded by a fiber-based NLP source, as one typical example. We expect that the NLP-related research area will continue to expand, and that NLP-based sources will also find more applications in the future.

Structural Input-output Properties of Low-order MIMO Interconnected Systems

Detailed in-depth overview on the structuredependent properties and specifics of MIMO (multiple-input, multiple-output) interconnected plants is performing, followed by consequent analysis. Originating from the basic MIMO Pand V-interconnected structures, a new P-V canonical form of interaction is proposed and investigated. For the considered MIMO systems, respective characteristic polynomials and equivalent transfer functions in decentralized control framework are derived and examined to serve for analysis and practical applications. Iterative approach for extending the equivalent plant transfer functions of lower orders to higher dimensionality is invented and duly applied. Special features regarding the steady-state behavior of interconnected plants and the related decentralized control systems are established for structural identification. Possible reversals in MIMO fundamental properties, resulting from parametric and/or structural plant variations are analysed as a point of special interest. As for engineering practice, the high dimensional systems can be decomposed into lower-order MIMO subsystems. So, it is still necessary to build comprehensive theoretical backgrounds for solving efficiently particular small-size MIMO sub-problems in a decentralized manner. The results of this paper can be applied to many practical applications concerning complex MIMO systems.

20922 加減速時に対応した油圧アクティブエンジンマウントの防振制御

Recently, from the viewpoint of global environmental protection, fuel consumption regulations for automobiles are required. To improve the fuel consumption, replacing gasoline engine with diesel engine and reduced-cylinder operation are considered. However, the vibration becomes large in these methods. Hydraulic active engine mount which cope with both fuel economy and ride comfort has been studied. Adaptive control which is generally used as a control method for an active engine mount cannot function well when the engine frequency varies. In this research, engine vibration suppression using model matching control method with characteristic transfer function matrix is aimed and its effectiveness is confirmed by basic experimental equipment. In addition, the combination of model matching control and adaptive control is considered.

3A1-R04 上肢姿勢角度と動的加速度による相互補償法を用いた電動前腕義手の制御(ウェアラブルロボティクス)

This paper describes multimodal sensor control of powered transradial prosthesis applying mutual compensation method on dynamic acceleration and upper limb posture angle. The target of developing the control method is to improve the stability of accelerometer-based upper limb posture angle estimation in the multimodal sensor control system. The proposed method measures the dynamic acceleration and upper limb posture angle (static acceleration) by using differences in the dynamic characteristic of two accelerometers of the same type. Two experimental devices for identification of accelerometer dynamic characteristic transfer function. An identification experiment was conducted for the angle input accelerometer and the estimated 2nd order transfer function had a fit rate difference of approximately 1%.

Programmable ferroelectric tunnel memristor

We report an analogously programmable memristor based on genuine electronic resistive switching combining ferroelectric switching and electron tunneling. The tunnel current through an 8 unit cell thick epitaxial Pb(Zr[0.2]Ti[0.8])O[3] film sandwiched between La[0.7]Sr[0.3]MnO[3] and cobalt electrodes obeys the Kolmogorov-Avrami-Ishibashi model for bidimensional growth with a characteristic switching time in the order of 10^-7 seconds. The analytical description of switching kinetics allows us to develop a characteristic transfer function that has only one parameter viz. the characteristic switching time and fully predicts the resistive states of this type of memristor.

A Straightforward Methodology to Modeling High Power Factor AC–DC Converters

In this paper, a straightforward methodology to modeling high power factor (HPF) ac-dc converters is presented. The proposed methodology is based on the averaging technique directly applied to the converter under modeling. An averaged large-signal equivalent circuit is thus generated, which is useful to perform extremely fast simulations. From the large-signal model, both a steady-state and a small-signal analysis can be carried out to completely model the converter, achieving any desired steady-state characteristic and small-signal transfer function. The presented methodology is very intuitive and allows designers to achieve a natural understanding of the converter behavior. The methodology is illustrated with a HPF buck-boost converter operating in discontinuous conduction mode. Simulation and experimental results are provided to validate the proposed methodology.

550 $^{\circ}\hbox{C}$ Integrated Logic Circuits using 6H-SiC JFETs

This letter reports the design, fabrication, and electrical characteristics of inverter, NAND, and NOR logic circuits using 6H-silicon carbide (SiC) depletion-mode junction field-effect transistors. All circuits function with high performance at temperatures from 25 °C to 550 °C. The core inverter has an outstanding dc characteristic transfer function with a steep slope, including a gain of >; -20 up to 500 °C, and a logic threshold that is well centered in the logic swing. NOR and NAND gates were likewise tested in this temperature range, and dynamic characteristics are presented. This SiC technology provides a platform for applications demanding reliable digital circuits at temperatures higher than 300 °C, well beyond the capability of silicon technology.

Restoration of the Spread Function in Nondestructive Testing: Theory and Experiments

Measurement systems can be regarded as input--output systems represented by a characteristic instrument transfer function. The characterization of the experimental setup enables a quantitative evaluation of its sensitivity and resolution, a comparison of relative performance among several systems, and inverse data restoration through deconvolution procedures. The direct inversion introduces either ill-conditioned sets of equations or singularities. One approach is to regularize the instabilities through minimum-entropy considerations. Another approach is to develop alternative methodologies to by-pass the singularity problems. Following the theoretical work, experiments were planed and conducted so as to characterize the transfer function of measurement systems in the areas of ultrasonic and industrial radiography. The experimental ultrasonic and radiography results and the applications of the methodologies for the characterization of an ultrasonic measurement system are presented and discussed.