Electrical Cycling Research Articles

Effectiveness of Rehabilitative Interventions Beginning within the First Month of Stroke Onset in Improving Lower Extremity-related Outcomes: A Systematic Review and Network Meta-Analysis

Reviews about early interventions, which are important in stroke rehabilitation due to significant neural plasticity, are relatively less. This study objective was to investigate the effectiveness of different interventions started within one-month post-stroke in improving lower extremity-related outcomes as compared to conventional rehabilitation and the corresponding effectiveness ranking. Cochrane Library, Ovid, PubMed, and Scopus were searched for articles dated up to 18 March 2022. Randomised controlled trials were included if they evaluated the effectiveness of two or more different non-drug, non-invasive, and non-surgical interventions which were started within one-month post-stroke on lower extremity-related outcomes. Network meta-analysis revealed that transcranial direct current stimulation, repetitive transcranial magnetic stimulation, mirror therapy, cycling, transcutaneous auricular vagus nerve stimulation, neuromuscular electrical stimulation (NMES), combination of robot and NMES, and thermal stimulation were significantly more effective in improving lower extremity motor function than conventional rehabilitation. In improving mobility, mirror therapy, cycling, and thermal stimulation were significantly more effective. In enhancing balance, physio ball, transcutaneous electrical nerve stimulation, cycling, thermal stimulation, and robot showed significantly higher effectiveness. Thermal stimulation scored the highest effectiveness ranking in improving lower extremity motor function and mobility whereas robot and backward walking achieved the highest effectiveness ranking in improving balance and gait speed respectively.

Unconventional polarization fatigue in van der Waals layered ferroelectric ionic conductor CuInP2S6

Recent progress in two-dimensional ferroelectrics greatly expands the versatility and tunability in van der Waals heterostructure based electronics. However, the switching endurance issue that widely plagues conventional ferroelectrics in practical applications is hitherto unexplored for van der Waals layered ferroelectrics. Herein, we report the observation of unusual polarization fatigue behaviors in van der Waals layered CuInP2S6, which also possesses finite ionic conductivity at room temperature. The strong intertwinement of the short-range polarization switching and long-range ionic movement in conjunction with the van der Waals layered structure gives rise to unique morphological and polarization evolutions under repetitive electric cycles. With the help of concerted chemical, structural, lattice vibrational and dielectric analyses, we unravel the critical role of the synergy of ionic migration and surface oxidation on the anomalous polarization enhancement and the eventual polarization degradation. This work provides a general insight into the polarization fatigue characteristics in ionically-active van der Waals ferroelectrics and delivers potential solutions for the realization of fatigue-free capacitors.

Mechanical-electrical-chemical coupling study on the stabilization of a hafnia-based ferroelectric phase

The metastable polar orthorhombic phase is believed to be the origin of the ferroelectricity of hafnia-based films. The adjustment of stain, oxygen vacancies and dopant during film deposition and the wake-up electric cycling are common strategies to induce the ferroelectricity in hafnia. However, none of them could independently render the ferroelectric phase to be the most stable phase from the theoretical calculation results. The exact external conditions to stabilize orthorhombic phase still remain elusive. In this paper, we investigate the effects of the type, distribution, concentration, and charge state characteristics of oxygen vacancies and the uniaxial strain on the crystal’ energy, dielectric constant and spontaneous polarization (Ps); In addition, the impact of the applied electric field parallel to the Ps on the crystal’ energy is explored by first-principles calculations. It is challenging to independently stabilize the ferroelectric phase of hafnia-based films by a single component owing to the rather strict conditions. Surprisingly, the ferroelectricity can be easily obtained when simultaneously considering the effects of oxygen vacancies, uniaxial strain, and applied electric fields, suggesting the extremely important mechanical-electrical-chemical coupling effects. This work provides an explanation for the typical wake-up phenomenon in hafnia and a guidance for film applications.

Failure Log Analytics for Reducing Electrical Machine Downtime using Deep Learning

Electrical machine downtime reduces productivity across various operation times that are addressed using stored data logs in the controller. Analyzing such logs is useful in preventing/ reducing machine downtime through precise controller options. This article proposes a Downtime Reduction-focused Log Analytical Model (DR-LAM) for improving the machine operation time by reducing operation failures. In this model, deep learning is employed for differentiating the production-less electrical cycles in correlation with the previous output. This differentiation is conditional using run-time failures and failed operation cycles. Therefore the logs are analyzed based on the above differentiations for precise problem identification. The training for the deep learning network is provided using previous differentiated cycle logs improving the detection ratio.

Dynamic Spectral Modulation Enabled by Conductive Polymer-Integrated Plasmonic Nanodisk-Hole Arrays.

The electrically driven optical performance modulation of the plasmonic nanostructure by conductive polymers provides a prospective technology for miniaturized and integrated active optoelectronic devices. These features of wafer-scale and flexible preparation, a wide spectrum adjustment range, and excellent electric cycling stability are critical to the practical applications of dynamic plasmonic components. Herein, we have demonstrated a large-scale and flexible active plasmonic nanostructure constructed by electrochemically synthesizing nanometric-thickness conductive polymer onto spatially mismatched Au nanodisk-hole (AuND-H) array on the poly(ethylene terephthalate) (PET) substrate, offering low-power electrically driven switching of reflective light in a wide wavelength range of 550-850 nm. The composite structure of the polymer/AuND-H array supports multiple plasmonic resonance modes with strong near-field enhancement and confinement, which provides an excellent dynamic spectral modulation platform. As a result, the PPy/AuND-H array achieves 18.4% reversible switching of spectral intensity at 780 nm and speedy response time, as well as maintains a stable dynamic modulation range at two-potential cycling between -0.6 and 0.1 V after 200 modulation cycles. Compared to the case of the PPy/AuND-H array, the PANI/AuND-H array obtains a more extensive intensity modulation of 25.1% at 750 nm, which is attributed to the significant differences in the extinction coefficient between the oxidized and reduced states of PANI, but its modulation range degrades apparently after 20 cycles driven at applied voltages between -0.1 and 0.8 V. Additionally, the cycling stability could be further improved by reducing the modulation voltage range. Our proposed electromodulated composite structure provides a promising technological proposal for dynamically plasmonic reconfigurable devices.

Three-stage integration system with solid oxide fuel cell, alkali metal thermal electric converter and organic Rankine cycle for synergistic power generation

Three-stage integration system with solid oxide fuel cell, alkali metal thermal electric converter and organic Rankine cycle for synergistic power generation

Experimental study on flow control system of an electric pump-fed cycle for thrust control

An electric pump-fed cycle can enable the electrical control of pump revolutions and rapidly vary the propellant flow rate. This paper proposes the pump control method as a flow control system of an electric pump-fed cycle. In order to evaluate the applicability of the designed flow control system, the test equipment that simulates an electric pump-fed cycle was constructed, including the Li-ion battery power system and communication instruments. The designed PID controller demonstrated rapid flow stabilization and robustness compared to the system without a controller. Meanwhile, under the initial pressurized condition in the run tank that simulated an engine start-up sequence, the controller response delay occurred was more than 500 ms. In addition, the dynamic loads, such as the water hammer effects and overshoot, were identified. The start-up sequence of an EP cycle was adjusted to alleviate those issues. Consequently, the supply stabilizing time and overshoot were adjusted to 400 ms and 1.7 %, respectively. This study can be the first step in utilizing an electric pump-fed cycle for the thrust control technology in the upper stage of a mission.

Temperature enhanced early detection of internal short circuits in lithium-ion batteries using an extended Kalman filter

Fuel shortages and environmental concerns primarily drive the recent growth in electrification. Lithium-ion batteries are the preferred power source for electric vehicles and other applications due to their high energy and power densities. Among potential issues that can affect Li-ion batteries, thermal runaway is a significant concern, believed to be primarily caused by internal short circuits. Therefore, early internal short circuit detection has become a critical task for any Li-ion battery-powered engineering system prioritizing safety. This paper presents a novel online internal short circuit detection method based on the state vector augmentation of an extended Kalman filter with: (i) voltage and surface temperature observations, (ii) a hysteresis state, and (iii) a state related to the internal short circuit. The proposed method is assessed numerically, mimicking an electrical vehicle battery working cycle. The framework allows for an online estimation of the internal short circuit state while remaining computationally lean, thus potentially allowing for implementation into commercial BMSs, and it is proven to capture the internal short circuit occurrence within safety limits. Additionally, the advantages of including both voltage and surface temperature observations have been highlighted. Future work envisaged towards field implementation of the technique in BMS is eventually and briefly discussed.

Feasible domain of cycling operating conditions and model parameters for Holby–Morgan model of platinum catalyst degradation in PEMFC

In the paper, electrochemical behavior of platinum based cathode catalyst in a polymer electrolyte membrane fuel cell is studied under non-symmetric square-wave electric potential cycling applied in accelerated stress test. Following the modeling by Holby and Morgan, degradation due to Pt dissolution, ion diffusion, and oxide coverage is performed with respect to cycling operating conditions and model parameters. The computer simulation demonstrates impact of the electrochemical surface area loss rate under variation of the temperature, pH, platinum particle diameter, loading, Pt to Carbon volume fraction, and their simultaneous effect. From physical consistency and multi-parametric sensitivity analysis, a statement on feasible domain of the parameters for the PEMFC operation is concluded.

Examining the ferroelectric characteristics of aluminum nitride‐based thin films

AbstractThe discovery of ferroelectricity in AlN‐based thin films, including Al1‐xScxN and Al1‐xBxN, over the past few years has spurred great research interests worldwide. In this review, we carefully examined the latest developments for these ferroelectric films with respect to alloy composition, temperature, film thickness, deposition condition, and fatigue endurance by electric field cycling. Looking ahead, there is an urgent need to resolve the challenge of large current leakage faced by these films, which necessitates a combined efforts from both simulations and experiments to identify the root cause and eventually come up with engineering strategies to suppress such leakage. In addition, overcoming the thickness scaling challenge to push ferroelectric thin film down to a few nanometers for better device miniaturization will also be of great interest. Considering the somewhat unexpected discovery of AlN‐based thin films with potential ferroelectric application, we believe that it will be also rewarding to further explore other III‐V‐based semiconductor materials.

Polydopamine-triggered adhesive and conductive hydrogel for Morse code communication at polar environments

Flexible electronics have been extensively explored for health monitoring and soft robotics. However, conventional hydrogels are inevitably frozen in polar environments and easily dehydrated, and have weak surface adhesion. Inspired by the natural mussel adhesive mechanism, we designed a polydopamine-polyacrylamide-LiCl (PPL) hydrogel with high electrical conductivity, high stretchability, and strong surface adhesion under low-temperature conditions. The PPL hydrogel exhibits robust adhesion (68.8 kPa), high electrical conductivity (384 S m−1 at room temperature, and 26 S m−1 at −40 °C), superior stretchability (1200%), and cycling stability (3000 cycles). The hydrogel sensor can accurately measure human joint movements, making them suitable for use in information encryption and decryption through Morse code even in polar environments (−60 °C). Further research in this area can lead to innovative solutions for communication and health monitoring in extreme conditions.

Enhanced Switching Reliability of Hf0.5Zr0.5O2 Ferroelectric Films Induced by Interface Engineering.

Ferroelectric materials have been widely researched for applications in memory and energy storage. Among these materials and benefiting from their excellent chemical compatibility with complementary metal-oxide-semiconductor (CMOS) devices, hafnia-based ferroelectric thin films hold great promise for highly scaled semiconductor memories, including nonvolatile ferroelectric capacitors and transistors. However, variation in the switched polarization of this material during field cycling and a limited understanding of the responsible mechanisms have impeded their implementation in technology. Here, we show that ferroelectric Hf0.5Zr0.5O2 (HZO) capacitors that are nearly free of polarization "wake-up"─a gradual increase in switched polarization as a function of the number of switching cycles─can be achieved by introducing ultrathin HfO2 buffer layers at the HZO/electrodes interface. High-resolution transmission electron microscopy (HRTEM) reveals crystallite sizes substantially greater than the film thickness for the buffer layer capacitors, indicating that the presence of the buffer layers influences the crystallization of the film (e.g., a lower ratio of nucleation rate to growth rate) during postdeposition annealing. This evidently promotes the formation of a polar orthorhombic (O) phase in the as-fabricated buffer layer samples. Synchrotron X-ray diffraction (XRD) reveals the conversion of the nonpolar tetragonal (T) phase to the polar orthorhombic (O) phase during electric field cycling in the control (no buffer) devices, consistent with the polarization wake-up observed for these capacitors. The extent of T-O transformation in the nonbuffer samples is directly dependent on the duration over which the field is applied. These results provide insight into the role of the HZO/electrodes interface in the performance of hafnia-based ferroelectrics and the mechanisms driving the polarization wake-up effect.

Enhancing polarization retention in BiFeO3 domain wall nanodevices through controlled space charge redistribution

Ferroelectric thin films with binary switchable polarization offer promising applications in domain wall (DW) memory. However, achieving reliable polarization retention in size-reduced devices remains challenging. In this study, we present a planar ferroelectric BiFeO3 DW nanodevice demonstrating stable polarization retention through electrical cycling. By precisely controlling the device size, including the width and gap of planar Pt electrodes, we observed a back-switching process in switched polarization within 20 min, as characterized by ex-situ piezoresponse force microscopy (PFM). To overcome this issue, long-time alternating voltage pulse cycling effectively suppressed the back-switching behavior, leading to symmetrized polarization coercive voltages of the device. PFM characterization further confirmed the persistence of the artificially created DW between the electrode pair. This improved polarization retention was attributed to the migration of mobile charged defects, such as oxygen vacancies, at the domain boundary. The presence of these defects generated a local built-in field, which screened the net polarization induced by the charged DW. Upon erasing the DW, the local built-in field gradually dissipated during opposite voltage poling, resulting in restored poor polarization retention and asymmetric coercive voltage in the nanodevices. This work presents a promising approach to utilize defect redistribution for stabilizing the switched polarization in the development of high-density ferroelectric DW memory.

Evolving electromechanical properties of defect engineered Pb(Zr,Ti)O3-based piezoceramics

Chemical modification is the frequently-adopted strategy to enhance the electromechanical properties of piezoelectric ceramics. However, chemically modified piezoelectric materials will inevitably produce point defects, such as dopant ions, oxygen vacancies, etc. In this study, we investigated the properties of defect-engineered Pb(Zr,Ti)O3 (denoted by PSZT–Fe) polycrystals after aging, quenching, poling, and de-aging processes. At the same time, a general mechanism on the strength of defect dipole is also put forward to explain the corresponding changes. After aging, the spontaneous polarization of PSZT-Fe can be changed instantly upon application of external electric field, but the defect dipole and its defect symmetry can’t change simultaneously. Therefore, after the external electric field is removed, the defective dipole would drive the electric domain back to its original state, resulting in restorable strain effect and macroscopic pinch polarization. Bipolar electric field cycling can effectively redistribute oxygen vacancies to a random state, so that the aged PSZT-Fe can recover the electrical properties of typical ferroelectrics, similar to quenched samples. The spontaneous polarization and defect dipole in the poled PSZT-Fe ceramics are driven by an external electric field parallel to each other, which results in the emergence of internal bias field, accounting for the asymmetric hysteresis loop.

A novel low-loss and high-stability (1-x)Na0.98NbO3–xBi(Al0.5Y0.5)O3 lead-free composite ceramics for dielectric energy storage capacitors

Environmentally friendly, high-performance, lead-free dielectric ceramic capacitors are urgently required for efficient and clean energy storage devices. However, most ferroelectric capacitors require excessively high electric fields to achieve large energy storage densities. In this study, we designed and fabricated a (1-x)Na0.98NbO3–xBi(Al0.5Y0.5)O3 (abbreviated as (1-x)NN-xBAY) composite system with different BAY doping levels using a traditional solid-state reaction method. By introducing 12 mol% BAY into nonstoichiometric NN, the polarization–electric field loop of the 0.88NN–0.12BAY ceramic became significantly slender and showed a superior relaxor behavior. Consequently, a remarkably low dielectric loss of tanδ < 0.005, high energy storage density of ∼ 4.64 J/cm3, and high efficiency of ∼ 85.98 % were simultaneously obtained in the 0.88NN–0.12BAY ceramic under a moderate electric field of 223.47 kV/cm. Furthermore, it exhibited ultrahigh stability in the temperature range of 25–200 °C and wide frequency range of 1–200 Hz, even after 108 electrical cycles. This study demonstrated a promising candidate material for energy storage devices operating under low or medium electric fields.

Off-design of a CO2-based mixture transcritical cycle for CSP applications: Analysis at part load and variable ambient temperature

This work focuses on the off-design analysis of a simple recuperative transcritical power cycle working with the CO2 + C6F6 mixture as working fluid. The cycle is air-cooled and proposed for a state-of-the-art concentrated solar plant with solar salts as heat transfer fluid in a hot region, with a cycle minimum and maximum temperature of 51 °C and 550 °C at design conditions. The design of each cycle heat exchanger (primary, recuperator and condenser) is carried out in MATLAB with referenced models and the turbine designed in CFD, providing performance maps adopted by the cycle operating in sliding pressure. The off-design of the cycle is developed with a routine simulating the thermodynamic conditions of the cycle at variable ambient temperature and thermal inputs down to 40 % of the nominal value. The results show that the cycle can efficiently run in a wide range of part load conditions and ambient temperatures, from around 0 °C to over 40 °C, with net electric cycle efficiencies from 45 % to 36 %: according to the control philosophy proposed, the condenser fans are fixed at design speed, while the cycle operates in sliding pressure, when is possible. The results evidence the flexibility and good performances of the proposed system in various operating conditions.

Comparative life cycle assessment of battery-electric and diesel underground mining trucks

The mining sector is currently confronted with an energy market and evolving regulatory landscape that exerts pressure on the industry to consistently enhance its strategies and decision-making in support of sustainable practices. Traditionally, the ore is transported using heavy-duty trucks powered by diesel engines which have been identified as a primary contributor to environmental degradation. An emerging and technologically advanced solution of considerable interest is the implementation of battery-electric trucks, which still generates some uncertainty about its actual impact on the environment. The primary hypothesis under investigation is that battery-electric vehicles have significantly lower environmental impacts than conventional combustion vehicles. Thorough research is needed to bridge this knowledge gap and robustly understand the environmental effects of these technologies in the mining context. This study uses Life Cycle Assessment to evaluate the potential environmental impacts of battery-electric trucks compared to diesel trucks in a theoretical underground mine. The study analyses the environmental impacts around three main stages: the raw material supply for the manufacture of the vehicles, the energy supply (electricity or diesel fuel), and other indirect impacts associated with the operation of both types of trucks. The characterization methodology used is the ReCiPe2016 Midpoint (Hierarchical) using open-access software OpenLCA v1.10.3 for the impact assessment. The functional unit selected is one ton of material transported over 1 km. Our results for the baseline Chilean scenario indicate that diesel trucks have a considerably greater environmental impact in two of the five categories studied: global warming potential and stratospheric ozone depletion. The energy supply is the ‘hotspot’ for the electric truck life cycle, while the diesel truck life cycle has the operation and the energy supply as the main environmental impact sources due to the upstream and direct emissions associated with diesel supply and combustion, respectively. However, when considering particulate matter formation and water consumption, electric trucks exhibit higher impacts due to the technologies employed for generating the electricity used to charge their batteries. Furthermore, the environmental profile of the electric truck improves considerably when renewable sources of electricity substantially substitute coal in the electricity mix, as projected in the Chilean policy context. The main novelty of this study is that it is the first initiative comparing a battery-electric truck with a diesel truck considering an approach to the underground operation reality for the mining sector.

Effects of two different paradigms of electrical stimulation exercise on cardio-metabolic risk factors after spinal cord injury. A randomized clinical trial.

To examine the combined effects of neuromuscular electrical stimulation-resistance training (NMES-RT) and functional electrical stimulation-lower extremity cycling (FES-LEC) compared to passive movement training (PMT) and FES-LEC in adults with SCI on (1) oxygen uptake (VO2), insulin sensitivity and glucose disposal in adults with SCI; (2) Metabolic and inflammatory biomarkers; (3) skeletal muscle, intramuscular fat (IMF) and visceral adipose tissue (VAT) cross-sectional areas (CSAs). Thirty-three participants with chronic SCI (AIS A-C) were randomized to 24 weeks of NMES-RT + FES or PMT + FES. The NMES-RT + FES group underwent 12 weeks of evoked surface NMES-RT using ankle weights followed by an additional 12 weeks of progressive FES-LEC. The control group, PMT + FES performed 12 weeks of passive leg extension movements followed by an additional 12 weeks of FES-LEC. Measurements were performed at baseline (BL; week 0), post-intervention 1 (P1; week 13) and post-intervention 2 (P2; week 25) and included FES-VO2 measurements, insulin sensitivity and glucose effectiveness using the intravenous glucose tolerance test; anthropometrics and whole and regional body composition assessment using dual energy x-ray absorptiometry (DXA) and magnetic resonance imaging to measure muscle, IMF and VAT CSAs. Twenty-seven participants completed both phases of the study. NMES-RT + FES group showed a trend of a greater VO2 peak in P1 [p = 0.08; but not in P2 (p = 0.25)] compared to PMT + FES. There was a time effect of both groups in leg VO2 peak. Neither intervention elicited significant changes in insulin, glucose, or inflammatory biomarkers. There were modest changes in leg lean mass following PMT + FES group. Robust hypertrophy of whole thigh muscle CSA, absolute thigh muscle CSA and knee extensor CSA were noted in the NMES-RT + FES group compared to PMT + FES at P1. PMT + FES resulted in muscle hypertrophy at P2. NMES-RT + FES resulted in a decrease in total VAT CSA at P1. NMES-RT yielded a greater peak leg VO2 and decrease in total VAT compared to PMT. The addition of 12 weeks of FES-LEC in both groups modestly impacted leg VO2 peak. The addition of FES-LEC to NMES-RT did not yield additional increases in muscle CSA, suggesting a ceiling effect on signaling pathways following NMES-RT. identifier NCT02660073.

Cardiac muscle-restricted partial loss of Nos1ap expression has limited but significant impact on electrocardiographic features.

Genome-wide association studies have identified sequence polymorphisms in a functional enhancer of the NOS1AP gene as the most common genetic regulator of QT interval and human cardiac NOS1AP gene expression in the general population. Functional studies based on in vitro overexpression in murine cardiomyocytes and ex vivo knockdown in zebrafish embryonic hearts, by us and others, have also demonstrated that NOS1AP expression levels can alter cellular electrophysiology. Here, to explore the role of NOS1AP in cardiac electrophysiology at an organismal level, we generated and characterized constitutive and heart muscle-restricted Nos1ap knockout mice to assess whether NOS1AP disruption alters the QT interval in vivo. Constitutive loss of Nos1ap led to genetic background-dependent variable lethality at or right before birth. Heart muscle-restricted Nos1ap knockout, generated using cardiac-specific alpha-myosin heavy chain promoter-driven tamoxifen-inducible Cre, resulted in tissue-level Nos1ap expression reduced by half. This partial loss of expression had no detectable effect on the QT interval or other electrocardiographic and echocardiographic parameters, except for a small but significant reduction in the QRS interval. Given that challenges associated with defining the end of the T wave on murine electrocardiogram can limit identification of subtle effects on the QT interval and that common noncoding NOS1AP variants are also associated with the QRS interval, our findings support the role of NOS1AP in regulation of the cardiac electrical cycle.

Technical-economic and environment benefit analyses of a novel building attached photovoltaic system.

This study proposed a novel building attached photovoltaic (BAPV) system mainly comprised of the PV system, building with household appliances, electric vehicle (EV), and power grid. Effect analyses of four typical factors are conducted, including the number of batteries, PV system supporting type, azimuth, and tilt angles of PV panels. The results show that the BAPV system with 8 batteries, an open PV system supporting type, an azimuth angle of 0°, and a tilt angle of 30.5° is relatively optimal. The operation, economic, and environment benefit performances of the BAPV system are analyzed. The results reveal that the annual effective output electricity of the BAPV system is 58.3 MWh, of which about 20 MWh is consumed by household appliances and EV or stored in batteries, and 38.3 MWh is sold to the power grid. The annual performance ratio of the BAPV system is 82.7%. Based on the annual nominal power generation quantity of the PV system, the effective output electricity occupies about 89%, and the energy loss part occupies 11%. The levelized cost of electricity (LCOE) and cost recovery cycle of the BAPV system are 0.132 yuan/kWh and 8.7 years, respectively. For the whole lifetime, the emission reduction quantities of carbon dioxide, dust, sulfur dioxide, and nitrogen oxide of the BAPV project are 786.3 t, 4.225 t, 7.275 t, and 6.9 t. The results of this study demonstrate the technical and economic feasibilities as well as the acceptable environmental protection performance of the proposed BAPV system, and this paper will contribute to the research and development works of BAPV systems.