Alternating current heating techniques for lithium-ion batteries in electric vehicles:Recent advances and perspectives

The significant decrease in battery performance at low temperatures is one of the critical challenges that electric vehicles(EVs)face,thereby affecting the penetration rate in cold regions.Alternating current(AC)heating has attracted widespread attention due to its low energy consumption and uniform heating advantages.This paper introduces the recent advances in AC heating from the perspective of practical EV applications.First,the performance degradation of EVs in low-temperature environments is introduced briefly.The concept of AC heating and its research methods are provided.Then,the effects of various AC heating methods on battery heating performance are reviewed.Based on existing studies,the main factors that affect AC heating performance are analyzed.Moreover,various heating circuits based on EVs are categorized,and their cost,size,complexity,efficiency,reliability,and heating rate are elaborated and compared.The evolution of AC heaters is presented,and the heaters used in brand vehicles are sorted out.Finally,the perspectives and challenges of AC heating are discussed.This paper can guide the selection of heater implementation methods and the optimization of heating effects for future EV applications.

Reversibility of visual field defects through induction of brain plasticity: vision restoration, recovery and rehabilitation using alternating current stimulation

For decades visual field defects were considered irreversible because it was thought that in the visual system the regeneration potential of the neuronal tissues is low.Nevertheless,there is always some potential for partial recovery of the visual field defect that can be achieved through induction of neuroplasticity.Neuroplasticity refers to the ability of the brain to change its own functional architecture by modulating synaptic efficacy.It is maintained throughout life and just as neurological rehabilitation can improve motor coordination,visual field defects in glaucoma,diabetic retinopathy or optic neuropathy can be improved by inducing neuroplasticity.In ophthalmology many new treatment paradigms have been tested that can induce neuroplastic changes,including non-invasive alternating current stimulation.Treatment with alternating current stimulation(e.g.,30 minutes,daily for 10 days using transorbital electrodes and^10 Hz)activates the entire retina and parts of the brain.Electroencephalography and functional magnetic resonance imaging studies revealed local activation of the visual cortex,global reorganization of functional brain networks,and enhanced blood flow,which together activate neurons and their networks.The future of low vision is optimistic because vision loss is indeed,partially reversible.

Effects of alternating current interference on corrosion of X60 pipeline steel

With rapid economic development in China, demand for energy and transportation is growing. Due to the limitations of factors such as terrain and traffic, a large number of buried oil and gas pipelines are parallel to high- voltage transmission lines and electrified railways over long distances. Alternating pipelines is very serious in laboratory experiments were current （AC） corrosion of such cases. In this work, carried out with an electrochemical method in a simulated soil solution at various AC current densities from 0 to 200 A]m2 and AC frequencies from 10 to 200 Hz. Experimental results indicated that with an increase in the AC current density, the corrosion po- tential of an X60 steel electrode shifted negatively, the anodic current density increased significantly, and the corrosion rate increased. Moreover, with an increase in the AC frequency, the corrosion potential of the X60 electrode shifted positively and the anodic current density decreased, which led to a decrease in the corrosion rate. Furthermore, the morphology of X60 electrodes indicated that uniform corrosion occurred at a low AC current density; while corrosion pits were found on the X60 electrode surface at a high AC current density, and deep corrosion pits seriously damaged the pipelines and might lead to leakage.

Sediment Movement in Periodic Alternating Current

The present paper summarizes the results of previous studies, including the structure and principle of the rotary ring flume for researching the fine sediment movement, the mechanism of the flume, method of eliminating the influence of the centrifugal force and sediment movement experiments with periodic alternating current. Also included are the experiment-based relationship among sediment concentration, bed shear stress and silt carrying capacity, a proposed erosion-deposition function and bed erosion-deposition calculation together with the results of verification.

Flow separation control over an airfoil using continuous alternating current plasma actuator

The flow separation control over an NACA 0015 airfoil using continuous alternating current(AC)dielectric barrier discharge(DBD)plasma actuator is investigated experimentally and numerically.This work is intended to report some observations made from our experiment,to which little attention is paid in the previous studies,but which is thought to be important to the understanding of control of complex flow separation with AC DBD.To this end,the response of separated flow to AC plasma actuation is visualized through the time-resolved particle image velocimetry(PIV)measurement,whereas numerical simulation is carried out to complement the experiment.The flow control process at chord-based Reynolds number(Re)of 3.31×105 is investigated.It is found that the response of external flow to plasma forcing is delayed for up to tens of milliseconds and the delay time increases with angle of attack increasing.Also observed is that at the intermediate angle of attack near stall,the forced flow features a well re-organized flow pattern.However,for airfoil at high post-stall angle of attack,the already well suppressed flow field can recover to the massively separated flow state and then reattach to airfoil surface with the flow pattern fluctuating between the two states in an irregular manner.This is contrary to one’s first thought that the forced flow at any angles of attack will become well organized and regular,and reflects the complexity of flow separation control.

Monitoring the spontaneous wetting process of hydrophobic microporous membrane assisted by alternating current impedance spectroscopy

In the process of membrane absorption,spontaneous wetting of hydrophobic microporous membrane causes membrane modification and increases membrane phase mass transfer resistance,which have attracted wide interest.However,due to the limitations of previous testing methods,the study of the spontaneous membrane wetting process is limited.Herein,we present a method for monitoring spontaneous membrane wetting by measuring its alternating current(AC)impedance.The impedance tests of the PVDF flat membranes and hollow fiber membranes were conducted in a two-electrode system.The results of equivalent circuit fitting indicate that the impedance value of the unwetted membrane is about 1.02×10^(10)Ω,which is close to the theoretical value of 1.4×10^(10)Ω,and this method can quantify the electrochemical impedance value of membranes with different degrees of spontaneous wetting.In addition,a method of impedance test for real-time monitoring of spontaneous wetting was designed.During the experiment,the timeliness and continuity of this method are confirmed with exact judgment under different conditions.In future work,the impedance data will be used to build model to predict the percentage of membrane wetting degree.

Characterization of alternating current impedance properties of biomedical electrodes

To study the alternating current （AC） impedance properties of Ag/AgC1 electrocardiograph （ECG） electrodes, the electrode pair was gel-to-gel connected, and then the electrical potential was recorded after a safe stimulating current passes through the electrode pair, so the AC impedance data of ECG electrodes were obtained. Varying the frequency and value of stimulating current, the detailed comparison and analysis of AC impedance properties of the electrodes were performed, and the stability was further characterized by using the continuous measurement within 24 h. The experimental results show that the AC impedance values of electrodes decreased, and then slightly increased with the increase of frequency of stimulating current. The minimum AC impedance value was obtained when the frequency was changed to 10 kHz. When the stimulating current increased, the AC impedance values of electrodes showed a slight decrease, but did not change significantly. Besides, the continuous measurement results show that the impedance value presented a significant increase in the initial 30 min, and then was stabilized in the following measuring process.

Soft measurement model on torque of alternating current electrical dynamometer including copper loss and iron loss

Alternating current electrical dynamometer is a common device to measure the torque of engines, such as the gasoline engine. In order to solve the problems such as high cost, high energy consumption and complicated measurement system which exists in the direct measurement on the torque of alternating current electrical dynamometer, copper loss and iron loss are taken as two key factors and a soft-sensing model on the torque of alternating current electrical dynamometer is established using the fuzzy least square support vector machine (FLS-SVM). Then, the FLS-SVM parameters such as penalty factor and kernel parameter are optimized by adaptive genetic algorithm, torque soft-sensing is investigated in the alternating current electrical dynamometer, as well as the energy feedback efficiency and energy consumption during the measurement phase of a gasoline engine loading continual test is obtained. The results show that the minimum soft-sensing error of torque is about 0.0018, and it fluctuates within a range from -0.3 to 0.3 N·m. FLS-SVM soft-sensing method can increase by 1.6% power generation feedback compared with direct measurement, and it can save 500 kJ fuel consumption in the gasoline engine loading continual test. Therefore, the estimation accuracy of the soft measurement model on the torque of alternating current electrical dynamometer including copper loss and iron loss is high and this indirect measurement method can be feasible to reduce production cost of the alternating current electrical dynamometer and energy consumption during the torque measurement phase of a gasoline engine, replacing the direct method of torque measurement.

Electrical Characteristics of an Alternating Current Plasma Igniter in Airflow

The electrical characteristics of an alternating current （AC） plasma igniter were investigated for a working gas of air at atmospheric pressure. The discharge voltage and current were measured in air in both breakdown and stable combustion processes, respectively, and the current-zero phenomena, voltage-current （V-I） characteristics were studied for different working gas flow rates. The results indicated that the working gas between anode and cathode could be ionized to generate gas discharge when the voltage reached 8 kV, and the maximum current was 33.36 A. When the current came to zero, current-zero phenomena appeared with duration of 2 #s. At the current-zero moment, dynamic resistance between electrodes became extremely high, and the maximum value could reach 445 kf~, which was the main factor to restrain the current. With increasing working gas flow rates, the gradient of V-I characteristic curves was increased, as was the dynamic resistance. At a constant driven power, the discharge voltage increased.

EFFECT OF DIFFERENT WAVEFORM'S ALTERNATING CURRENT ON THE INCISION'S SENSITIVITY

Compared with the conventionally used i=iosinωt alternating current, using asymmetric triangular and pulse wave as input signals can greatly enhance the incision's sensitivity of 'dE/dt-E'oscillogram.

Basic Concepts for Alternating Current through Educational Videos

This article highlights the importance of complementing classes through educational videos, especially in disciplines exclusively with lectures. This proposition is exemplified through basic concepts in alternating current for both single-phase and three-phase circuits, which are critical in the formation of electrical engineers, mechanics, chemists, etc. The main objective of conducting educational videos is to make learning more attractive and stimulate interest in acquiring the knowledge of certain topics, given their importance in professional life in different engineering areas. The videos, filmed in laboratory and of short duration, aim to complement and consolidate the content taught in the classroom lectures.

A Device for Measuring 3-Phase Alternating Current at a Distance

We have made a preliminary study on a possibility to build a device, which could measure three-phase alternating current at a distance. This report gives a brief look at the theoretical background related with such a device and derives several mathematical results associated with the theory and the structure of the device. Our results suggest that such a device can be built, assuming the distances between the three current-carrying wires and the two sensors of the device are known accurately enough. There are ways to measure these distances, but this article does not concentrate on them.

Frequency Regulation of Alternating Current Microgrid Based on Hierarchical Control Using Fuzzy Logic

An alternating current(AC)microgrid is a system that integrates renewable power,power converters,controllers and loads.Hierarchical control can manage the frequency of the microgrid to prevent imbalance and collapse of the system.The existing frequency control methods use traditional proportion integration(PI)controllers,which cannot adjust PI parameters in real-time to respond to the status changes of the system.Hierarchical control driven by fuzzy logic allows real-time adjustment of the PI parameters and the method used a two-layer control structure.The primary control used droop control to adjust power distribution,and fuzzy logic was used in the voltage loop of the primary control.The secondary control was added to make up for frequency deviation caused by droop control,and fuzzy logic was used in the secondary frequency control to deal with the dynamic change of frequency caused by the disturbances of loads.The proposed method was simulated in Matlab/Simulink.In the primary control,the proposed method reduced the total harmonic distortion(THD)of two cycles of the output voltage from 4.19%to 3.89%;in the secondary control,the proposed method reduced the frequency fluctuation of the system by about 0.03 Hz and 0.04 Hz when the load was increased and decreased,respectively.The results show that the proposed methods have a better effect on frequency maintenance and voltage control of the AC microgrid.

Cortico–subcortical spatiotemporal dynamics in Parkinson’s disease can be modulated by transcranial alternating current stimulation

Objective:We investigated changes in cortico–subcortical spatiotemporal dynamics to explore the treatment mechanisms oftranscranial alternating current stimulation(tACS)in patientswith Parkinson’s disease(PD).Methods:Resting-state functional magnetic resonance imaging(rs-fMRI)data were collected from 20 patients with PD and 20 normal controls(NC).Each patient with PD received successivemultidisciplinary intensive rehabilitation treatment and tACStreatment over a one-year interval.Individual functional brain network mapping and co-activation pattern(CAP)analysis were performed to characterize cortico–subcortical dynamics.Results:The same tACS electrode placement stimulated different proportions of functional brain networks across the participants.CAP analysis revealed that the visual network,attentional network,and default mode network co-activated with the thalamus,accumbens,and amygdala,respectively.The pattern characterized by thede-activation of the visual network and the activation of the thalamus showed a significantly low amplitude in the patients with PD than inNCs,and this amplitude increased after tACS treatment.Furthermore,the co-occurrence of cortico–subcortical CAPs was significantly higherin patients with PD than in NCs and decreased after tACS treatment.Conclusions:This study investigated cortico–subcortical spatiotemporaldynamics in patients with PD and further revealed the tACS treatmentmechanism.These findings contribute to understanding cortico–subcortical dynamics and exploring noninvasive neuromodulationtargets of cortico–subcortical circuits in brain diseases,such as PD,Alzheimer’s disease,and depression.

Research and exploration of direct current power supply and distribution systems for Antarctic research stations

The power supply and distribution systems for Antarctic research stations have special characteristics.In light of a worldwide trend toward a gradual increase in the application of renewable energy,an analysis was performed to assess the feasibility of achieving a direct current power supply and distribution at Antarctic research stations by comparing the characteristics of direct current and alternating current electricity.Research was also performed on the status quo and future trends in direct current power supply and distribution systems in Antarctica research stations in combination with case studies.

Fabrication of TiO_2 Nanotube Arrays by Rectified Alternating Current Anodization

Anodization is a popular method of preparing TiO2nanotube array films（TiNTs） by using direct current（DC）power as the driving voltage.In this study,three driving voltage modes,namely,the sine alternating current（sine） mode,the full-wave rectification of sine waves via four diodes（sine-4D,where D means diode） mode,and the DC mode,were used to prepare TiNTs by anodization.At 20 V,TiNTs were formed under sine-4D mode but only irregular porous TiO2films were formed under DC mode.At 50 V,TiNTs formed under both the sine-4D and DC modes.No TiNTs formed in the sine mode anodization at either 20 or 50 V.Compared with the DC mode,the sine-4D mode required a lower oxidation voltage for TiNT formation,which suggests that sine-4D is an economical,convenient,and efficient driving voltage for TiNT preparation by anodization.The morphologies and structures of TiNT samples anodized at 50 V in the sine-4D and DC modes at different oxidation time（1,5,10,30,60,and 120 min） were analyzed.TiNT growth processes were similar between the studied modes.However,the growth rate of the films was faster under the sine-4D mode than the DC mode during the first 30 min of anodization.

Protocol on transcranial alternating current stimulation for the treatment of major depressive disorder:a randomized controlled trial

Background:Transcranial alternating current stimulation(tACS)offers a new approach for adult patients with major depressive disorder(MDD).The study is to evaluate the efficacy and safety of tACS treating MDD.Methods:This is an 8-week,double-blind,randomized,placebo-controlled study.Ninety-two drug-naive patients with MDD aged 18 to 65 years will receive 20 daily 40-min,77.5-Hz,15-mA sessions of active or sham tACS targeting the forehead and both mastoid areas on weekdays for 4 consecutive weeks(week 4),following a 4-week observation period(week 8).The primary outcome is the remission rate defined as the 17-item Hamilton depression rating scale(HDRS-17)score≤7 at week 8.Secondary outcomes are the rates of response at weeks 4 and 8 and rate of remission at week 4 based on HDRS-17,the proportion of participants having improvement in the clinical global impression-improvement,the change in HDRS-17 score(range,0-52,with higher scores indicating more depression)over the study,and variations of brain imaging and neurocognition from baseline to week 4.Safety will be assessed by vital signs at weeks 4 and 8,and adverse events will be collected during the entire study.Discussion:The tACS applied in this trial may have treatment effects on MDD with minimal side effects.Trial registration:Chinese Clinical Trial Registry,ChiCTR1800016479;http://www.chictr.org.cn/showproj.aspx?proj=22048.

Clinical efficacies of treating refractory insomnia patients with estazolam plus alternating current magnetic field

As one of common physical and mental ailments, insomnia may cause serious adverse effects on a patient＇s daily life. And serious accidents occur in long-term cases.1 Despite comprehensive treatments, 9.38%-17.0% of the treated insomniacs fail to benefit at all. Thus the term of ＂refractory insomnia＂ has been coined.24 At present, there is no literature reporting the roles of estazolam plus alternating current magnetic field （ACMF） for treating insomnia. In the present study, estazolam plus ACMF was employed for the patients with refractory insomnia so as to explore the clinical efficacies of such a combined modality.

Evolution of Solidification Structure of Hypereutectic Al-Si Alloy Under a Novel Low-Voltage Alternating Current Pulse

The effect of a novel low-voltage alternating current pulse(ACP)controlled by transformer and silicon controlled rectifier on the solidification structure of Al-20%Si alloy was investigated.The results indicated that the remarkable segregation of primary Si occurred during the solidification,and even dendrites of a-Al phase appeared at the center of samples under ACP.The thickness of segregation layer decreased first and then increased with current density increasing from 0 to 300 Acm^(-2).The primary Si existed with long pole or five petal star-shaped without ACP.However, the morphology of primary Si phases changed to block under ACP,and the sizes of blocky Si decreased obviously with increasing current density from 110 to 300 Acm^(-2).The formation mechanism of the structure of hypereutectic AI-20%Si alloy was also discussed under ACP.

Spurious-mode vibrations caused by alternating current poling and their solution process for Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3) single crystals

The effects of alternating current poling(ACP)at 80℃on electrical properties of[001]-oriented 0.72 Pb(Mg_(1/3)Nb_(2/3))O_(3)-0.28PbTiO_(3)(PMN-28PT)single crystals(SCs)have been investigated.The square-wave ACP SCs poled at high voltage(HV,5 kV_(rms)/cm)occasionally showed large fluctuations and low opposite values of piezoelectric coefficient(d_(33)=±1370 pC/N)in one plate.This revealed spuriousmode vibrations(SMV)of impedance spectrum.However,after depolarizing and repolarizing the sample with a sine-wave ACP at low voltage(LV,3.5 kV_(rms)/cm),the d_(33) enhanced to be 1720 pC/N(+26%)and did not exhibit large fluctuation or opposite values in one plate any more.The impedance spectrum became clean and the abnormal SMV disappeared.We proposed four possible mechanisms of the SMV,and speculate that the main cause maybe by macro-scale sub-domain structure and/or phase change in the main domain structure and/or phase in the SC plate due to the specific poling conditions not eternal mechanical damage of PMN-PT SCs.This study will be useful to realize a high d_(33) and improve other properties of PMN-PT ACP SC ultrasonic transducers without any SMV for high-frequency medical imaging equipment.