Diagonal Resistivity Research Articles

Non-equilibrium excited-state fractionally quantized Hall effects observed via current bias spectroscopy

Studies of fractional quantum Hall effects (FQHE) across various two-dimensional electronic systems (2DES) have helped to establish the equilibrium FQHE many-body ground states with fractionally charged excitations and composite particles in condensed matter. Then, the question arises whether an FQHE system driven to non-equilibrium can approach a different stationary state from the known equilibrium FQHE states. To investigate this question, we examine FQHE over filling factors, ν, 2 ≥ ν ≥ 1 under non-equilibrium finite bias conditions realized with a supplementary dc-current bias, IDC, in high mobility GaAs/AlGaAs devices. Here, we show that all observable canonical equilibrium FQHE resistance minima at ∣IDC∣ = 0 undergo bimodal splitting vs. IDC, yielding branch-pairs and diamond shapes in color plots of the diagonal resistance, as canonical FQHE are replaced, with increasing IDC, by excited-state fractionally quantized Hall effects at branch intersections. A tunneling model serves to interpret the results.

Shear behavior of hollow clay brick masonry wallet coated with short jute fiber reinforced mortar

The objective of this study is to present a new method of reinforcing masonry using layers of mortar reinforced with short jute fibers. Mortars were produced with 0%, 2% and 3% jute fibers with cementitious matrices free of calcium hydroxide. The effectiveness of the reinforced mortar was evaluated through diagonal compression tests of hollow ceramic brick masonry prisms. The prisms were coated on both sides. The experimental results demonstrated that the diagonal resistance of the fiber system increased by 28 to 30% and presented greater resistance to elastic deformation during load application, with deformation coefficients 2 and 3 times greater for 2% and 3% of fibers, respectively. Therefore, jute fibers prove to be a sustainable and efficient alternative for masonry reinforcement applications, with maximum applied loads considerably higher than the unreinforced system, in addition to better crack control.

Synthesizing 2h/e2 resistance plateau at the first Landau level confined in a quantum point contact

A comprehensive understanding of quantum Hall edge transmission, especially a hole-conjugate of a Laughlin state such as a 2/3 state, is critical for advancing fundamental quantum Hall physics and enhancing the design of quantum Hall edge interferometry. In this study, we show a robust intermediate 2h/e2 resistance quantization in a quantum point contact (QPC) when the bulk is set at the fractional filling 2/3 quantum Hall state. Our results suggest the occurrence of two equilibration processes. First, the co-propagating 1/3 edges moving along a soft QPC arm confining potential fully equilibrate and act as a single 2/3 edge mode. Second, the 2/3 edge mode is further equilibrated with an integer 1 edge mode formed in the QPC. The complete mixing between them results in a diagonal resistance value quantized at 2h/e2. Similar processes occur for a bulk filling 5/3, leading to an intermediate (2/3)h/e2 resistance quantization. This finding highlights the importance of understanding the equilibration mechanisms that occur between different edge modes, offering insights into the processes of edge equilibration.

Operation Control Method for High-Speed Maglev Based on Fractional-Order Sliding Mode Adaptive and Diagonal Recurrent Neural Network

The speed profile tracking calculation of high-speed maglev trains is mainly affected by running resistance. In order to reduce the adverse effects and improve tracking accuracy, this paper presents a maglev train operation control method based on a fractional-order sliding mode adaptive and diagonal recurrent neural network (FSMA-DRNN). First, the kinematic resistance equation is established due to the three types of resistance that occur during the actual operation of a train: air resistance, guide eddy current resistance, and suspension frame generator coil resistance. Then, the FSMA-DRNN control law and parameter update law are designed, and a FSMA-DRNN operation controller is composed of three parts: speed feed forward, fractional-order sliding mode adaptive equivalent control, and diagonal recurrent neural network resistance compensation. Furthermore, by using the designed operation controller, it is proven effective by the Lyapunov theory for the stability of the closed-loop control system. Apart from the proposed theoretical analysis, the proposed approaches are verified by experiments on the high-speed maglev hardware-in-the-loop simulation platform Rt-Lab, in line with the 29.86 km test line and a five-car train from the Shanghai maglev, showing the effectiveness and superiority for operation optimization.

Shear behavior of polypropylene fiber-reinforced concrete beams containing recycled aggregate and crumb rubber

The growth of unavoidable waste rubber and the demolition of old concrete structures have become a concern for environmental sustainability. The incorporation of crumb rubber and demolished concrete into the new concrete mix is likely to promote environmentally friendly practices. This paper investigates the shear behavior of concrete beams containing crumb rubber (CR), recycled concrete aggregate (RCA), and polypropylene (PP) fiber. A total of fifteen reinforced concrete (RC) beams were prepared with recycled concrete aggregate (RCA) (0%–50%), CR as fine aggregate (0%–10%), and PP fiber fractions (0%–1%). All RC beams made without any shear reinforcement were tested under a four-point bending test up to failure. The ultimate shear strength, crack pattern, post-diagonal cracking, concrete strain, toughness, and deformation behavior of fresh concrete properties were investigated at different combinations. The surface strain of concrete was closely observed by using Digital Image Correlation (DIC) technique. The experimental result suggested that the introduction of CR in the concrete mix negatively affects the ultimate shear strength, post diagonal cracking resistance, toughness, and deformability of the beam. These effects may be remedied and enhanced by inserting PP fiber in the concrete at RCA replacement levels up to 30%. The beam made of 30% RCA along with 5% CR and 1% PP fiber demonstrated the best performance in terms of shear resistance, deformability, and toughness. Interestingly, the application of 50% RCA with or without CR and PP fiber adversely affected the shear strength parameters of concrete. The beam deformability increased with the addition of a small percentage of rubber (up to 5%). The post-diagonal crack resistance increased with the presence of fibers, whereas the response is the opposite with the addition of rubber.

Even-denominator fractional quantum Hall state in conventional triple-gated quantum point contact

The even-denominator states have attracted considerable attention owing to their possible applications in future quantum technologies. In this letter, we first report a 3/2 diagonal resistance, indicating the existence of a 3/2 state in a nanometer-sized triple-gated quantum point contact (QPC) fabricated on a high-mobility (not ultra-high-mobility) single-layer two-dimensional (2D) GaAs wafer. The center gate plays a crucial role in realizing the QPC’s 3/2 state. Our observation of the 3/2 state using a conventional QPC device, which is a suitable building block for semiconductor quantum devices, paves a new path for the development of semiconductor-based quantum technologies.

An alternative experimental methodology to determine the diagonal cracking resistance of steel-reinforced concrete beams

An alternative experimental method for predicting the diagonal shear cracking resistance of steel-reinforced concrete beams is developed in this paper. Conventional extensometric strain-gauge rosettes are placed on the lateral surfaces of a set of four beams. As diagonal cracking propagates through the beams, the load–strain curves flatten out at a plateau and the mechanical property under consideration may be determined. The method is applied to four beams cast from pumpable and self-compacting concrete mixes with cement types I and IV containing electric arc furnace slag aggregates. The feasibility of applying standard design code formulas to the concretes containing these aggregates may therefore be studied and compared with other recent research works. Accurate experimental results were obtained with this method without having to interrupt the test for subjective visual appraisals of the test specimen.

Effects of mechanical perturbation gait training on gait and balance function in patients with stroke: A pre-post research study

Patients with stroke (PwS) demonstrate impaired gait and balance, and asymmetric gait, placing them at high risk of falls. We aimed to investigate the effects of a single training session that included mechanical external perturbation which resists forward movement of the paretic leg during its swing phase of walking on gait and balance in PwS. In a pre-post pilot study, gait asymmetry and balance function were assessed in 22 first-event chronic PwS (i.e., unilateral hemiparesis). PwS underwent tests during baseline and one week later, after participating in a single training session that resisted forward stepping during the swing phase of walking with a device secured around the patient's waist and connected diagonally to the patient’s foot by a tension cord. Ground reaction forces and center of pressure were sampled during treadmill gait to assess step length asymmetry. Performance-oriented mobility assessment (POMA), a two-minute walk test (2MWT), and the voluntary step execution test were also measured. We found no significant improvement in step length asymmetry. However, POMA scores, as well as voluntary step execution tests improved with a moderate effect size. It seems that applying diagonal resistance force to the swinging leg resulted in insufficient horizontal force. However, the improvement in the preparation phase, i.e., better weight-bearing abilities during the voluntary stepping, may be due to the compression force applied to the lower limb joints thus providing proprioceptive training. This suggests that proprioceptive training may improve gait performance in stroke patients in a very short training period.

Alternative Interpretation and Prediction of Quantum Hall Effect via Electron Pairing Picture

As a two-body system, hydrogen atom with quantum exact solution played an important role for explaining shell structure of multi-electron atoms. Inspired by this, we suggest an alternative interpretation of the integer and fractional quantum Hall effect (QHE) by establishing a direct connection between the exact solutions of a two-dimensional (2D) magnetically trapped electron-pair and the “fundamental” (non-fine) Hall hierarchies of a multi-electron system. We analyze the topology of the exact pair states and report the filling factors of the lowest Landau level based on the exact solutions, which fit the previously and recently reported spectrum of experimental data on the QHE states well and predict some new Hall plateaus for the plateau positions and the eigenenergies reflecting stability and plateau widths. The theoretical prediction associated with the relatively lower minima of the diagonal resistivity is in accurate agreement with the experimental datum spectrum of the fundamental QHE hierarchies.

Microwave resonance in a high-quality GaAs/AlGaAs two-dimensional electron system in the low-density and low-mobility condition

Radiation induced magnetoresistance oscillations are well known and readily observable in the high-quality two-dimensional (2D) electron system. Here, we report unexpected photoexcited transport, under a low-carrier density, low-mobility condition, in the high-quality GaAs/AlGaAs devices that exhibit the above-mentioned oscillations. This study reveals enhanced nonresonant magnetoresistance as well as microwave resonance that appear unrelated to the above-mentioned radiation-induced magnetoresistance oscillations. The positions of the resonance along the $B$ axis depends on the microwave power, the microwave frequency, and the direction of sweep of the magnetic field, as the photoexcited diagonal resistance is prominently enhanced over the dark value. Most remarkably, the observed microwave-induced resonance becomes unobservable below a characteristic cutoff frequency. These features suggest a bulk magnetoplasmon origin for the observed resonances. A picture including bottlenecks in transport within 2D electron systems and microwave modified tunneling at bottlenecks is suggested to help understand some aspects of experiment.

Influence of microwave photo-excitation on the transport properties of the high mobility GaAs/AlGaAs 2D electron system

ABSTRACTWe examined the influence of the microwave power on the diagonal resistance in the GaAs/AlGaAs two dimensional electron system (2DES), in order to extract the electron temperature and determine microwave induced heating as a function of the microwave power. The study shows that microwaves produce a small discernable increase in the electron temperature both at null magnetic field and at finite magnetic fields in the GaAs/AlGaAs 2DES. The heating effect at null field appears greater in comparison to the examined finite field interval, although the increase in the electron temperature in the zero-field limit appears smaller than theoretical predictions.

Structural Characteristics of Reinforced Palm Kernel Shell Concrete Deep Beams

This paper evaluates the structural characteristics of deep beams made from reinforced palm kernel shell concrete (PKSC) and normal weight concrete (NWC). Twelve PKSC and NWC deep beam samples, with and without shear reinforcement were tested under three-point loading and their structural behavior studied. The ultimate shear strength of PKSC beams increased with a decrease in the shear span-to- depth ratio. Post diagonal cracking shear resistance is greater in PKSC deep beams than beams of normal weight concrete. The shear capacity of the PKSC and NWC deep beams were assessed to be un-conservative using ACI 318-99, ACI 318-05, Eurocode (EC) 2 and a kinematic model, when compared with the experimental results. Nonetheless, this necessitated the development of a calibration procedure to correct the bias inherent in these models. Calibrated shear strength models revealed the compressive strength and the ratio of the shear span-to-total depth as significant influential parameters for correcting the inherent bias in the original deterministic shear strength models. The calibrated functional model of ACI-318-99 may produce conservative predictions, given this limited number of test specimens. Therefore future studies should investigate the reliability of the calibrated models, and quantifying the uncertainties in the estimated coefficients of parameters, using a much larger representative dataset.

B-periodic oscillations in the Hall-resistance induced by a dc-current-bias under combined microwave-excitation and dc-current bias in the GaAs/AlGaAs 2D system

We report the observation of dc-current-bias-induced B-periodic Hall resistance oscillations and Hall plateaus in the GaAs/AlGaAs 2D system under combined microwave radiation- and dc bias excitation at liquid helium temperatures. The Hall resistance oscillations and plateaus appear together with concomitant oscillations also in the diagonal magnetoresistance. The periods of Hall and diagonal resistance oscillations are nearly identical, and source power (P) dependent measurements demonstrate sub-linear relationship of the oscillation amplitude with P over the span 0 < P ≤ 20 mW.

Comparison of In-Plane Mechanical Performances of Masonry Walls Strengthened with Different Mortar Coatings Reinforced with Glass or Carbon Fiber Composite Meshes

The results of some diagonal compression tests performed on solid brick masonry samples (1160x1160x250 mm3) to evaluate and compare the effectiveness of different shear reinforcement techniques for existing masonry based of the application, on both sides of the wall, of a mortar coating layer reinforced with fiber composite meshes are presented and discussed in the paper. In particular, 30 mm and 10 mm thick mortar coatings, made of three different mortar types and reinforced by means of both glass and carbon-fibers composite meshes were considered. Significant resistance increases (about 110%) were attained in respect to plain masonry; moreover, it emerged that the meshes are able to prevent the masonry brittle collapse, absorbing tensile stresses in the cracked areas. By maintaining constant the coating thickness, better mortar characteristics determined an increase of the resistance increment ratio but a more rapid decrease of resistance after peak. Similar performances were attained by samples characterized by approximately constant values of shear stiffness and diagonal compression resistance. The differences attributable to the different type of meshes resulted minimal, due to the similar reinforcement percentage.

Behaviour of Bichromatic Microwave Induced Magnetoresistance Oscillations in the High Mobility GaAs/AlGaAs 2D electron System

Microwave radiation-induced magneto-resistance oscillations are examined under bichromatic excitation for various frequency combinations in order to obtain a better understanding of the lineshape observed in the dual excitation experiment of the high mobility GaAs/AlGaAs 2D electron system. Here, we examine superposition- or lack thereof- in the lineshape observed in the bichromatic experiment, and report a trend observed between the monochromatic and bichromatic responses of the oscillatory diagonal resistance.

Magneto-transport characteristics of a 2D electron system driven to negative magneto-conductivity by microwave photoexcitation

The magneto-transport characteristics of the negative conductivity/resistivity state in the microwave photo-excited two-dimensional electron system (2DES) is examined through a numerical solution of the associated boundary value problem. The results suggest, surprisingly, that a bare negative diagonal conductivity/resistivity state in the 2DES under photo-excitation should yield a positive diagonal resistance along with a sign reversal in the Hall voltage.

Evolution of the frequency-dependent polarization-angle phase-shift in the microwave radiation-induced magnetoresistance oscillations

We report the evolution of the phase shift, θ0, extracted from traces of the diagonal resistance, Rxx, vs. the linear polarization angle, θ, at oscillatory extrema of the microwave radiation induced magnetoresistance oscillations over the 36 ≤ f ≤ 40 GHz band in GaAs/AlGaAs system. A reference phase shift for the linear polarization angle in the vicinity of the specimen is obtained with the help of a sensitive carbon resistor. We fit an empirical cosine square law to the sinusoidal responses of Rxx vs. θ to extract the phase shift θ0. The quasi-continuous variation θ0 vs. f trace suggests a preferable polarization orientation for the specimen, and the f− and B− independence of overall average of θ0.

The effects of pelvic diagonal movements and resistance on the lumbar multifidus

[Purpose] The purpose of this study was to compare the effects of pelvic diagonal movements, made with and without resistance, on the thickness of lumbar multifidus muscles. [Subjects and Methods] Participants in this study were healthy subjects who had no musculoskeletal disorders or lumbar-related pain. Participants were positioned on their side and instructed to lie with their hip flexor at 40 degrees. Ultrasonography was used for measurement, and the values of two calculations were averaged. [Results] The thickness of ipsilateral lumbar multifidus muscles showed a significant difference following the exercise of pelvic diagonal movements. The results of anterior elevation movements and posterior depression movements also demonstrated significant difference. There was no significant difference in lumbar multifidus muscles thickness between movements made with and without resistance. [Conclusion] These findings suggest that pelvic diagonal movements can be an effective method to promote muscular activation of the ipsilateral multifidus. Furthermore, researchers have concluded that resistance is not required during pelvic diagonal movements to selectively activate the core muscles.

Measurement the thickness of the transverse abdominal muscle in different tasks.

[Purpose] This study examined the measurement of the thickness of the transverse abdominal muscle in different tasks. [Subjects and Methods] The subjects were eleven healthy adult females. Thicknesses of transverse abdominal muscle were measured in seven tasks in the supine position. The tasks were: 1) Resting state, 2) Maximal contraction of transverse abdominal muscle, 3) Maximal contraction of levator ani muscle, 4) Maximal simultaneous contraction of both transverse abdominal muscle and levator ani muscle, 5) Maximal simultaneous contraction of both transverse abdominal muscle and levator ani muscle with front side resistance added to both knee, 6) Maximal simultaneous contraction of both transverse abdominal muscle and levator ani muscle with diagonal resistance added to both knees, and 7) Maximal simultaneous contraction of both transverse abdominal muscle and levator ani muscle with lateral resistance added to both knees. [Results] The thicknesses of transverse abdominal muscle during maximal simultaneous contraction and maximal simultaneous contraction with resistance were greater than during the resting state. [Conclusion] The muscle output during simultaneous contraction and resistance movement were larger than that of each individual muscle.

Angular phase shift in polarization-angle dependence of microwave-induced magnetoresistance oscillations

We examine the microwave frequency $(f)$ variation of the angular phase shift, ${\ensuremath{\theta}}_{0}$, observed in the polarization-angle dependence of microwave-induced magnetoresistance oscillations in a high-mobility GaAs/AlGaAs two-dimensional electron system. By fitting the diagonal resistance ${R}_{xx}$ versus $\ensuremath{\theta}$ plots to an empirical cosine square law, we extract ${\ensuremath{\theta}}_{0}$ and trace its quasicontinuous variation with $f$. The results suggest that the overall average of ${\ensuremath{\theta}}_{0}$ extracted from Hall bar device sections with length-to-width ratios of $L/W=1$ and 2 is the same. We compare the observations with expectations arising from the ``ponderomotive force'' theory for microwave radiation-induced transport phenomena.