Nonlinear Resistance Research Articles

Rescuing RRAM-Based Computing From Static and Dynamic Faults

Emerging resistive random access memory (RRAM) has shown the great potential of in-memory processing capability, and thus attracts considerable research interests in accelerating memory-intensive applications, such as neural networks (NNs). However, the accuracy of RRAM-based NN computing can degrade significantly, due to the intrinsic statistical variations of the resistance of RRAM cells. In this article, we propose SIGHT, a synergistic algorithm-architecture fault-tolerant framework, to holistically address this issue. Specifically, we consider three major types of faults for RRAM computing: 1) nonlinear resistance distribution; 2) static variation; and 3) dynamic variation. From the algorithm level, we propose a resistance-aware quantization to compel the NN parameters to follow the exact nonlinear resistance distribution as RRAM, and introduce an input regulation technique to compensate for RRAM variations. We also propose a selective weight refreshing scheme to address the dynamic variation issue that occurs at runtime. From the architecture level, we propose a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">general</i> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">low-cost</i> architecture accordingly for supporting our fault-tolerant scheme. Our evaluation demonstrates almost no accuracy loss for our three fault-tolerant algorithms, and the proposed SIGHT architecture incurs performance overhead as little as 7.14%.

A physical memristor based Muthuswamy\u2013Chua\u2013Ginoux system

In 1976, Leon Chua showed that a thermistor can be modeled as a memristive device. Starting from this statement we designed a circuit that has four circuit elements: a linear passive inductor, a linear passive capacitor, a nonlinear resistor and a thermistor, that is, a nonlinear “locally active” memristor. Thus, the purpose of this work was to use a physical memristor, the thermistor, in a Muthuswamy–Chua chaotic system (circuit) instead of memristor emulators. Such circuit has been modeled by a new three-dimensional autonomous dynamical system exhibiting very particular properties such as the transition from torus breakdown to chaos. Then, mathematical analysis and detailed numerical investigations have enabled to establish that such a transition corresponds to the so-called route to Shilnikov spiral chaos but gives rise to a “double spiral attractor”.

Magnetic Field Strength and Temperature Effects on the Behavior of Oil Well Cement Slurry Modified with Iron Oxide Nanoparticles and Quantified with Vipulanandan Models

Abstract The focus of this study was to investigate the methods that could potentially be easy to adopt in field to modify cement slurry rheological properties in situ during the installation of oil and gas wells. In this study, we investigated the effects of magnetic field strengths and temperatures on the rheological properties of an oil well cement (Class H) modified with iron oxide nanoparticles (NanoFe2O3). Also, the sensitivity of using electrical resistivity in monitoring changes in the cement slurry was also investigated. The water-to-cement ratio used in this study was 0.38, since it is a popular ratio used in oil well cementing. The NanoFe2O3 contents (average particle size of 30 nm) in the cement slurry were varied up to 1 % by the weight of cement. The temperature was varied from 25°C to 85°C. The magnetic field strength was varied up to 0.6 T. The initial electrical resistivity of the cement slurry modified with NanoFe2O3 decreased by 6 % to 52 % based on the NanoFe2O3 content, temperature, and magnetic field strength. The shear thinning behavior of the cement slurry with and without NanoFe2O3 has been quantified using the Vipulanandan rheological model and compared to the Herschel-Bulkley model. The results show that the Vipulanandan rheological model predicted the shear thinning relationship between the shear stress and shear strain rate of the NanoFe2O3-modified cement slurry very well with the maximum shear stress tolerance. The rheological properties of the cement slurry modified with NanoFe2O3 under different magnetic field strengths have been correlated to the electrical resistivity of the cement slurry using a nonlinear resistivity and Vipulanandan property correlation models. Thus, the performance of the cement slurry with and without NanoFe2O3 can be characterized based on the electrical resistivity, which can be used as a real-time monitoring tool in the field.

Design of class‐E M amplifier with consideration of parasitic non‐linear capacitances and on‐state resistance

In this study, the design of the class-E M­ power amplifier is presented. In this design, the effects of on-state resistance and non-linear parasitic capacitances of the transistors are investigated. Two metal oxide semiconductor field-effect transistors (MOSFETs) of IRFZ24N and IRF510 with different drain-source resistances are used in the presented circuits. In the given design, the values of the operational frequency and duty ratio are 3.5 MHz and 0.5, respectively. This study shows the importance of considering non-linear parasitic elements of MOSFET, especially drain-source resistance in the designing of the class-E M power amplifiers. It is shown that the class-E M power amplifier with high MOSFET drain-source resistance needs high DC input voltage for both the primary and auxiliary circuits. In the previous works, non-linear on-state resistance and non-linear drain-source and gate-drain capacitances have not been included at the same time in the analyses. Two class-E M amplifiers contain IRF510 and IRFZ24N are designed, simulated, and measured. The efficiency equal to 96.6% with 11.851 W output power at 3.5 MHz and the efficiency equal to 88.4% with 12.361 W output power are achieved for presented class-E M amplifiers contain IRFZ24N and IRF510, respectively.

Three-Saddle-Foci Chaotic Behavior of a Modified Jerk Circuit with Chua’s Diode

This paper investigates the chaotic behavior of a modified jerk circuit with Chua’s diode. The Chua’s diode considered here is a nonlinear resistor having a symmetric piecewise linear voltage-current characteristic. To describe the system, we apply fundamental laws in electrical circuit theory to formulate a mathematical model in terms of a third-order (jerk) nonlinear differential equation, or equivalently, a system of three first-order differential equations. The analysis shows that this system has three collinear equilibrium points. The time waveform and the trajectories about each equilibrium point depend on its associated eigenvalues. We prove that all three equilibrium points are of type saddle focus, meaning that the trajectory of (x(t),y(t)) diverges in a spiral form but z(t) converges to the equilibrium point for any initial point (x(0),y(0),z(0)). Numerical simulation illustrates that the oscillations are dense, have no period, are highly sensitive to initial conditions, and have a chaotic hidden attractor.

A novel method for determining the three dimensional variation of non-linear thermal resistance at the mold-strand interface in billet continuous casting process

A three-dimensional numerical model has been developed to study the turbulent flow of the molten steel, heat transfer from the solidifying strand to the cooling water and the subsequent solidification within the mold of an industrial billet continuous casting process. Particular attention is paid to calculate the unknown non-linear thermal resistance at the mold-strand interface, based upon a physical formulation. The model results are validated with the data available in the literature, as well as from plant experimental data. Recirculation flows are observed near the mold walls, causing remelting of solidified shell. The results obtained from the simulations show that one of the major reasons for higher value of solidified shell thickness at the corner region than that at the off-corner region is the nature of recirculatory flows. The thermal resistance is found to vary along the casting direction as well as across the mold face. The plant data of solid shell thickness of the strand at mold exit shows that the current model involving physical formulation of thermal resistance at the mold-strand interface, provides a better estimation of the thermal behavior, compared to previous models involving empirical formulation for the thermal resistance or heat flux profiles at the interface.

Residual Offset in Silicon Hall-Effect Sensor: Analytical Formula, Stress Effects, and Implications for Octagonal Hall Plate Geometry

The Hall-effect magnetic sensors suffer from large offset that is described by the resistance mismatch in the Wheatstone bridge-like equivalent electrical circuit model of the Hall plate. After a first order cancellation of the raw offset using spinning current technique, a residual offset still exists, significantly limiting the accuracy of the Hall sensor in the detection of low magnetic field. In this paper we analyzed the residual offset in silicon Hall sensor using a nonlinear lumped resistor network model to derive a closed form expression. We further analyzed the residual offset in silicon Hall sensor under the influence of stress. Using these results, we show that eight-terminal, octagonal-shaped silicon Hall sensors employing eight-phase spinning current technique provide greater immunity to stress effects on residual offset due to a second order cancellation compared to the conventional four-phase spinning. The measurement results suggest superior offset performance of eight-terminal silicon Hall sensor.

The effect of selenium on the structural, morphology, optical, electrical properties of Cu2Te thin films for thermoelectric and photovoltaic applications

Synergistic optimization of optical and electrical properties of Cu2Te thin films was presented via doping with various content of selenium. Cu2Te1-xSex (x = 0.1, 0.2) thin films were successfully deposited by electron beam evaporation on silicon and glass substrate without any formation of non-stochiometric phases. X-ray diffractograms displayed that the deposited films have formed in a hexagonal single phase with a very slight shift owing to the incorporation of selenium, which is further affirmed by selected area electron diffraction pattern (SAED). The energy dispersive X-ray profile verified that selenium was successfully incorporated inside the Cu2Te matrix at the expense of Te. The cross-section view images illustrated that the thicknesses of studies films are about 200 nm. For x = 0.2, the films become smoother and grains are more identifiable of smaller size than Cu2Te0·9Se0.1, as visualized by FESEM and 3D AFM images. Over the wavelength range 200–2500 nm, the transmittance, reflectance, absorption edges, optical conductivity and electrical conductivity were reported. The values of band gap of both films are 1.45 and 1.65 eV. The refractive index of deposited films was analyzed by Single-oscillator model (WDD), oscillator energy (Eo), dispersion energy (Ed), and static refractive index (ns) were reported and discussed. Further, the ratio of free carrier concentration, the relaxation time (τ), third-order nonlinear susceptibility (χ(3)), nonlinear refractive index (n2), optical mobility (μopt) and optical resistivity (ρopt) greatly depend on the Se content. The electrical conductivity, thermoelectric power and power factors showed remarkable increase with increasing of selenium content. Solar cell device of the configuration glass/ITO/CdS/CdTe/Cu2Te1-xSex (x = 0.1, 0.2 mol)/Au was fabricated and demonstrated higher efficiency with increasing Se dopants.

Effect of pressure on the electrical properties of flexible NiPc thin films fabricated by rubbing-in technology

Nickel phthalocyanine (NiPc) film was deposited onto the surface of flexible conductive glass by rubbing-in technology and used to fabricate devices based on ITO/NiPc/CNT/rubber structure. The I–V characteristics of the devices were investigated under different uniaxial pressures of 200, 280, and 480 gf/cm2, applied perpendicular to the surface of the NiPc film. Results showed that the nonlinearity coefficients of the I–V curves are in the range of 2 to 3, which was found to be decreased with the increase of the pressure. The rectification ratio of the devices was estimated to be varied from 1.5 to 3 based on the applied pressure. Concluding, the resistance of the active layers was decreased with the increase of both pressure and voltage. We believe that using the rubbing-in technology under sufficient applied pressure it is possible to utilize NiPc for the development of various electronic devices such as diodes, nonlinear resistors, and sensors.

The Analysis of Shear Forces Flow around the Supports of Flat Slabs

This paper deals with both linear and non-linear analysis of shear forces distribution in the area near the supports of the flat slabs. With a cross-section ratio of cmax / cmin &gt; 3, the main amount of the shear stress is concentrated near the column or wall corners bases. As a consequence of this phenomenon, it is necessary to reduce the control perimeter when evaluating the punching shear resistance of a flat slab. The fragments of the flat slabs with the thickness of 200 mm supported by a wall with various loading conditions were analyzed. The results according to the Eurocode 2 were compared to a non-linear shear resistance evaluation that was calibrated based on the results from the previous experiments. Based on thus evaluated punching shear resistances, the theoretical reduced control perimeter was determined and subsequently it was compared to design model Eurocode 2. The physical basis for determining reduced control perimeters is based on the shear force concentration near the support.

Mechanism of the High- Tc Superconducting Dynamo: Models and Experiment

High-${T}_{c}$ superconducting (HTS) dynamos are experimentally proven devices that can produce large (more than a kiloamp) dc currents in superconducting circuits, without the thermal leak associated with copper current leads. However, these dc currents are theoretically controversial, as it is not immediately apparent why a device that is topologically identical to an ac alternator should give a dc output at all. Here, we present a finite-element model and a comparison of it with experiment that fully explain this effect. It is shown that the dc output arises naturally from Maxwell's laws when time-varying overcritical eddy currents are induced to circulate in a HTS sheet. We first show that our finite-element model replicates all of the experimental electrical behavior reported so far for these devices, including the dc output characteristics and transient electrical waveforms. Direct experimental evidence for the presence of circulating eddy currents is also obtained through measurements of the transient magnetic field profile across the HTS tape, using a linear Hall array. These results are also found to agree closely with predictions from the finite-element model. Following this experimental validation, calculated sheet current densities and the associated local electric fields are examined for a range of frequencies and net transport currents. We find that the electrical output from a HTS dynamo is governed by the competition between transport and eddy currents induced as the magnet transits across the HTS tape. The eddy currents are significantly higher (approximately 1.5 times) than the local critical current density, and hence experience a highly nonlinear local resistivity. This nonlinearity breaks the symmetry observed in a normal ohmic material, which usually requires the net transport current to vary linearly with the average electric field. The interplay between local current densities and nonlinear resistivities (which both vary in time and space) is shown to systematically give rise to the key observed parameters of experimental HTS dynamo devices: the open-circuit voltage, the internal resistance, and the short-circuit current. Finally, we identify that the spatial boundaries formed by each edge of the HTS stator tape play a vital role in determining the total dc output. This offers the potential to develop alternative designs for HTS dynamo devices, in which the internal resistance is greatly reduced and the short-circuit current is substantially increased.

Conic Programming for Circuit Equations With Rational Current Controlled Resistors

This brief considers special nonlinear resistors are where the voltage is controlled by a polynomial of the current with arbitrary rational exponents, called rational current controlled resistors (RCCRs). It is discovered that nonlinear circuit equations with these special nonlinear resistors can be isomorphic to the Karush-Kuhn-Tucker (KKT) conditions of a convex optimization model. Moreover, three-dimensional rotated cones using the “tower of variables” technique are utilized to exactly reformulate the convex optimization model into tractable conic programming (CP). Through the proposed approach, the solution of the nonlinear circuit equations can be exactly obtained by solving the CP. Simulation results on several test systems with RCCRs demonstrate the effectiveness of the proposed method.

Measuring the power conversion losses in voltage source inverters

The power losses in a voltage source inverter (VSI) are the sum of the additional constant power losses of the local power supply, the inverter circuits as well as the main power conversion losses. Power conversion losses consist of the power losses on switches (e.g. static power losses on the resistances of the switches in the “on state” and the dynamic switching power losses), the power losses on the serial resistances of the filter inductor winding together with the resistances of all of the serial inverter connections and the power losses of the filter coil, which are dependent on the material of the filter coil core. All of these power conversion losses can be presented as losses on the one equivalent serial resistance that is connected serially with the filter coil. This nonlinear (depending on the load and the switching frequency) serial equivalent resistance Rse can be calculated from the parameters of the maximum point of the measured magnitude Bode plot of the control transfer function of the inverter. The paper presents the concept of measuring the Bode plots of the control transfer function in order to get the serial equivalent resistance and to calculate the power conversion losses of an experimental model and discusses the accuracy of the results.

Wiring techniques for large size silicon probe using electroplating

AbstractTo realize an uniformization of wiring thickness on a large size silicon probe, a design of wiring to supply current and electroplating conditions were analytically and experimentally evaluated. Circuit simulations adopted with nonlinear resistance elements clarified the distribution of current density on silicon probes. The voltage drop of current supply wiring on the silicon probe was necessary to be decreased to uniformize the thickness of wirings. Thus, the resistance of current supply wiring was decreased, and the bypass wirings were set on the silicon probe for decreasing the current distribution. As a result, the thickness of wirings was uniformized in the thick deviation of less than 1 µm on the silicon probe units. The experiments were qualitatively consistent with the circuit simulations.

Bursting oscillations with boundary homoclinic bifurcations in a Filippov-type Chua’s circuit

A modified version of the typical Chua’s circuit, which possesses a periodic external excitation and a piecewise nonlinear resistor, is considered to investigate the possible bursting oscillations and the dynamical mechanism in the Filippov system. Two new symmetric periodic bursting oscillations are observed when the frequency of external excitation is far less than the natural one. Besides the conventional Hopf bifurcation, two non-smooth bifurcations, i.e., boundary homoclinic bifurcation and non-smooth fold limit cycle bifurcation, are discussed when the whole excitation term is regarded as a bifurcation parameter. The sliding solution of the Filippov system and pseudo-equilibrium bifurcation of the sliding vector field on the switching manifold are analysed theoretically. Based on the analysis of the bifurcations and the sliding solution, the dynamical mechanism of the bursting oscillations is revealed. The external excitation plays an important role in generating bursting oscillations. That is, bursting oscillations may be formed only if the excitation term passes through the boundary homoclinic bifurcation. Otherwise, they do not occur. In addition, the time intervals between two symmetric adjacent spikes of the bursting oscillations and the duration of the system staying at the stable pseudonode are dependent on the excitation frequency.

Lean Mass Changes After 10-week Resistance Training Intervention In Adults With Down Syndrome

PURPOSE: To examine changes in body composition (i.e. lean mass) after a 10-week resistance training intervention in individuals with Down syndrome. METHODS: Data was collected on willing 18 - 40-year-old moderately active men and women with Down syndrome (age 24.4 ± 6.3 years, height 149.2 ± 11.2 cm, weight 72.02 ± 24.5 kg). Twelve participants completed 24 resistance training sessions (duration 45-60 minutes per session). Dual x-ray absorptiometry (DXA) was used to assess body composition both pre- and post-intervention (i.e. body fat, lean tissue mass, fat tissue, bone density). A nonlinear periodized resistance exercise program was implemented; made of light, moderate, and heavy resistances. The participants began the first two weeks of the intervention with exercises using light 12-15 RM Zone repetitions and moderate 8-10 RM Zone progressing from 1-3 sets over the two-week period of time. After that flexible period, using light, moderate, and heavy (4-6 RM zone) for 3 sets were rotated with toleration of the work out noted each training session. The resistance training intervention utilized a body part bodybuilding training program 3 days per week (consisting of 1 upper body, 1 lower body, 1 full body exercises). The exercises consisted of body weight exercises, machine based, resistance bands, and free weight exercises. Each program was individualized per participant regarding specific exercises based off of movement kinetics, understanding, skill, and strength levels. Participants were kept in a light to moderate intensity heart rate range via heart range chest monitoring straps. RESULTS: There was no significant difference between pre- and post-intervention for overall body mass (p=0.23), body fat (p=0.75), or bone mineral density (p=0.078). However, there was a significant increase between pre- and post-intervention in lean mass (p=0.033). CONCLUSIONS: A 10-week moderate resistance training intervention is a great enough stimulus to significantly increase lean muscle tissue in adults with Down syndrome. Therefore, implementing resistance training into an individual’s weekly routine for adults with Down syndrome is a viable option to increase lean muscle mass, which could also increase potential strength and motor skill, then increasing overall quality of life.

Analysis of arc surges in electric networks of the Arctic region

This work is devoted to the urgent issue of the analysis of arc surges in electric networks of the Arctic region of the Russian Federation, using the electric power system of the Kola Peninsula as an example. The article presents an approach to the development of a computational model of a power system in the Matlab software environment, the Simulink simulation application. When compiling the calculation model, the following points were taken into account: the model was in a three-phase formulation; the inductances of overhead power lines were taken into account; non-linear arc resistance was taken into account; grounding resistance was taken into account; the magnetic coupling between the phases and interphase capacitances were taken into account. Based on the results of the model, graphs of transients in the system were obtained for various operating modes. The correctness of the calculation model was checked on the following points: on the voltage, it is necessary that the phase voltages on the buses of the substation ΦC-24 correspond to the phase voltages at all points of the model and be shifted relative to each other by an angle of 120 °; current, current at all points of the system, the current must be symmetrical; according to the current of a single-phase short circuit, it is necessary that the value of the short circuit current obtained using the calculation model corresponds to the current value obtained in the analytical calculations. In the study of arc surges, more than 60 calculations were performed. The performed calculations showed the dependence of the overvoltage ratio on the fault location and the uneven distribution of overvoltages in the considered sections. An analysis of the results obtained in the work allows us to conclude that it is advisable to apply this approach to other electric power systems of the regions of the Russian Federation and other countries.

Effects Of A Non-linear Resistance Training Program On Biochemical And Physiological Health Parameters In Elderly

Resistance training (RT) has been shown to have positive effects on older adults’ health by increasing muscle mass and improving metabolic profile. Nonetheless, the potential benefits of a non-linear RT program on biochemical and physiological health parameters in older individuals are less known. PURPOSE: This study assessed the effects of an undulating-periodized (UP) RT program on glucose, cholesterol (total, HDL-c and LDL) and triacylglycerol (TG) concentrations in blood, and arterial blood pressure (BP). METHODS: Seventeen (n=9 men; n=8 women) untrained elderly individuals (64.2±2.0 years, 72.2±10.8 kg; 164.8±7.6 cm; 25.6±2.6 kg·m-2) with no previous RT experience were randomly assigned to either a linear training (n=8, LT) or UP-RT (n=9) program. After 3 weeks of familiarization, all participants performed three RT weekly bouts for 8 weeks. Blood samples were collected pre- and post-study after a 12-hour overnight fast, and biochemical analyses were carried out. Systolic and diastolic BP were measured using a digital sphygmomanometer. Statistical comparison was performed with the paired t test or Wilcoxon, and a repeated measures ANOVA was employed to determine interactions (Time=pre-test vs test; Group=LT vs UT and Time x Group). Effect size (ES) was calculated with Hedges g. RESULTS: Statistical analysis (Δ=X ±SD; P; ES) showed differences on basal glycemia for LT (-11.1±8.1 mg·dL-1; 0,006; -1.61) and UP (-5.7±4.2 mg·dL-1; 0.004; -0.65). There were changes in LDL (LT=-15.1±9.5 mg·dL-1; -1.18; 0.003, UP=-9.4±4.4 mg·dL-1; -0.33;<0.0002), total cholesterol (LT=-21.1±14.6 mg·dL-1; -1,19; 0,005, UT=-10.2±6.2 mg·dL-1; -0.28; 0.001) and TG (LT= -18.3±16.0 mg·dL-1; -0.56; 0.014, UP=-6.7±3.9 mg·dL-1; -0.24; 0.001) in both groups, but HDL-c remained statistically unchanged (LT= -2.6±6.3 mg·dL-1; -0.38; 0.277, UP=3.0±6.8 mg·dL-1; 0.27±0.223). There were no changes on either SBP or DBP in LT (-3.4±8.5 mmHg; -0.25; 0.289, and -3.2±5.7 mmHg; -0.48; 0.079, respectively) but there were in UP (-4.5±4.4 mmHg; -0.56; 0.015, and -4.0±4.3 mmHg; -0.83; 0.023, respectively). No significant between-group differences were found for any variable. CONCLUSIONS: A supervised RT program with either linear or UP provides improvements in cardiometabolic markers in older adults and, therefore, health enhancement.

Energy-efficient speed profile optimization for medium-speed maglev trains

This study addresses the problem of reducing the energy consumption of the medium-speed maglev (MSM) system by optimizing the train speed profile. Auxiliary stopping areas, the nonlinear resistance caused by the linear motor, and the suspension energy consumption are considered in the formulation of the speed profile optimization problem. Next, dynamic programming and mixed-integer linear programming (MILP) approaches that utilize these characteristics are proposed to solve the problem. The numerical results show that both approaches ensure MSM train safety and energy-efficient operation. Furthermore, the MILP approach could be used for emergency trajectory planning due to its shorter computational time.

Resistance induced P-bifurcation and Ghost-Stochastic resonance of a hybrid energy harvester under colored noise

In this paper, a hybrid energy harvester using two mechanisms of transduction namely piezoelectric and electromagnetic and subjected to the colored noise is investigated. Using the stochastic averaging method, the Fokker−Planck−Kolmogorov equation of the system is constructed whose the statistic response in the stationary state is the probability density. The mean square voltage and current are obtained for different values of the linear and nonlinear resistance as the output power generated by piezoelectric circuit and electromagnetic circuit. The stability of the harvester is investigated by using probability approach. In addition, combining the colored noise and coherence excitation, the Ghost-Stochastic resonance is observed through the mean residence time and improve the amount of energy harvested by the scavenger. The agreements between the analytical method and those obtained numerically validate the effectiveness of analytical investigations. The results obtained in this manuscript shows the interest to use the load resistance exhibiting the nonlinearity in this research field and also, these results reveal that, while the natural frequency is absent in the coherent excitation, the system performance can be improved for a certain value of noise intensity.