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Objectives The study aimed to assess the feasibility of recording electrically evoked compound action potentials (ECAPs) from the rat spinal cord. To achieve this, we characterized electrophysiological responses of dorsal column (DC) axons from electrical stimulation and quantified the relationship between ECAP and motor thresholds (ECAPTs and MTs). Material and methods Naive, anesthetized and freely behaving rats were implanted with a custom-made epidural spinal cord stimulation (SCS) lead. Epidural stimulation and recordings were performed on the same lead using specifically designed equipment. Results The ECAPs recorded from the rat spinal cord demonstrated the expected triphasic morphology. Using 20 μsec pulse duration and 2 Hz frequency rate, the current required in anesthetized rats to generate ECAPs was 0.13 ± 0.02 mA, while the average current required to observe MT was 1.49 ± 0.14 mA. In unanesthetized rats, the average current required to generate ECAPs was 0.09 ± 0.02 mA, while the average current required to observe MT was 0.27 ± 0.04 mA. Thus, there was a significant difference between the ECAPT and MT in both anesthetized and unanesthetized rats (MT was 13.39 ± 2.40 and 2.84 ± 0.33 times higher than ECAPT, respectively). Signal analysis revealed average conduction velocities (CVs) suggesting that predominantly large, myelinated fibers were activated. In addition, a morphometric evaluation of spinal cord slices indicated that the custom-made lead may preferentially activate DC axons. Conclusions This is the first evidence demonstrating the feasibility of recording ECAPs from the rat spinal cord, which may be more useful in determining parameters of SCS in preclinical SCS models than MTs. Thus, this approach may allow for the development of a novel model of SCS in rats with chronic pain that will translate better between animals and humans.

For saliency-based position sensorless drives, the switching frequency pulsewidth modulation (PWM) voltage injection can achieve noise-free position estimation which is suited for high-performance motion systems. However, considering the switching frequency injection, multiple phase currents should be sampled per PWM cycle instead of single average current. It leads to the implementation issue on the space-vector PWM (SVPWM) inverter using shunt resistor current sensing for machine control. In this article, a modified PWM injection instead of SVPWM injection is proposed for the saliency-based drive using shunt current sensing. It is concluded that at least two transient currents can be sampled per PWM cycle based on the proposed PWM control. More importantly, the field-oriented control is maintained when the saliency-based drive is applied. A 2 kW permanent magnet (PM) machine is used for the experimental verification. This article includes the position estimation comparison using either the proposed PWM injection with shunt resistors or standard SVPWM with Hall-effect sensors.

Average Current Mode (ACM) controlled synchronous DC–DC converters are increasingly required for computer power supplies and electric vehicle battery chargers. In this study, Generalized Hopfield N...

The aim of this work is to prepare a neutron noise calculator based on the second order of average current nodal expansion method (ACNEM). Generally, nodal methods have the ability to fulfill the neutronic analysis with adequate precision using coarse meshes as large as a fuel assembly size. But, for the zeroth order of ACNEM, the accuracy of neutronic simulations may not be sufficient when coarse meshes are employed in the reactor core modeling. In this work, the capability of second order ACNEM is extended for solving the neutron diffusion equation in the frequency domain using coarse meshes. For this purpose, two problems are modeled and checked including a slab reactor and 2D BIBLIS PWR. For validating of results, a semi-analytical solution is utilized for 1D test case, and for 2D problem, the results of both forward and adjoint neutron noise calculations are exploited. Numerical results indicate that by increasing the order of method, the errors of frequency dependent coarse mesh solutions are considerably decreased in comparison to the reference. Accordingly, the accuracy of second order ACNEM can be acceptable for the neutron noise calculations by using coarse meshes in the nuclear reactor core.

Present light-emitting diode (LED) drivers often exhibit difficulty in meeting the increasing demand for compact size, flexible multiphase configuration, accurate current regulation, and fast transient response. In this letter, we present an output-capacitorless modular LED driver that simultaneously achieves these attributes by the realization of monolithic integration and the employment of our proposed I 2 V 2 average current control. The proposed control based on pulsewidth modulation, considers the complete LED current profile to obtain the accurate current regulation and combines the feedforward signals of the inductor current, input voltage, and the output voltage to accelerate the transient response. To verify the proposed I 2 V 2 average current control scheme, we monolithically realize a modular LED driver that embodies a tiny 1.8 μH inductor and supports an input voltage range of 5–18 V, output LED current of 1 A, switching frequency of 2 MHz, LED current settling time of 1.3 μs, and the peak power efficiency of 94.5%. When being benchmarked against state-of-the-art counterparts, the proposed design features at least 2.6× smaller output inductor, 2.3× shorter settling time, and 2.5% higher peak power efficiency.

espanolEn este articulo se presenta el diseno, simulacion e implementacion de un cargador de baterias con baja distorsion armonica en corriente, a pequena escala. Se propone un diseno compuesto por dos convertidores boost en cascada, el primero funcionando como PFC y el segundo como un regulador de la corriente que se inyecta a las baterias. Adicionalmente, se presenta el procedimiento necesario para el diseno de los controladores de cada etapa. En la primera etapa se usa un control en modo corriente promedio y en la segunda etapa se usan dos controles que permiten emplear el metodo de carga de baterias, corriente constante - tension constante. Los controladores usados en ambas etapas son de tipo PI y junto con el circuito de potencia fueron simulados en los software PSIM® y MATLAB® y validados experimentalmente, obteniendo factores de potencia cercanos a 0,98 y distorsion armonica en corriente por debajo del 10%, cumpliendo asi con los requerimientos de la norma IEC 61000-3-2. Finalmente, se presentan las conclusiones. EnglishThis paper presents the design, simulation and implementation of a small scale battery charger with low harmonic distortion in current. It was proposed a design composed of two boost converters in cascade, the first operating as PFC and second as a regulator of the injected current to the batteries. Additionally, it was presented the procedure for the controllers design of each stage. In the first stage was used a control in average current mode and in the second stage were used two controls that enable you to employ the method of constant current - constant voltage in order to charge the batteries. In both stages were used the PI controllers and with the power electronic circuit were simulated in the PSIM® and MATLAB® software and validated experimentally In this tests, power factors close to 0.98 and harmonic distortion in current below 10% were obtained, complying with the requirements of the IEC 61000-3-2 standard. Finally, the conclusions are presented.

This work assesses the effectiveness of an artificial intelligence (AI) model based on an artificial neural networks (ANN) – genetic algorithm (GA) in the prediction of the behavior and optimization of the treatment of sulfate wastewaters with Bromophenol blue dye using an electro-oxidation (EO) process. Trials were made with a filter press-type reactor with a boron-doped diamond (BDD) anode. The ANN model was trained with 51 electrolytic experiments by using the electrolysis time, flow, current density, pH and dye concentration as input variables and the discoloration efficiency as the output one. The performance of ANN was measured with RMSE and MAPE values of 10.73 % and 8.81 %, respectively, calculated from real and predicted values. Optimum conditions determined by GA were reached for the inputs of 10 min, 11.9 L min−1, 31.25 mA cm−2, 2.8 and 41.25 mg L−1, giving a discoloration efficiency of 88.8 ± 0.3 %, close to 95.5 % predicted by the model. To validate the AI model, the same experimental conditions were applied to treat wastewaters with Bromothymol blue and Thymol blue, with analogous structures to Bromophenol blue, and a mixture of the three dyes by EO. In all cases, the loss of color decayed following a pseudo-first-order kinetics, with similar apparent rate constants. For the dye mixture, 69 % COD was reduced at 60 min, with 13 % average current efficiency and 0.26 kW h (g COD)-1 energy consumption. The AI model is a strong tool to design, control and operate the EO process with a BDD anode to treat wastewaters with similar dyes.

The efforts to increase capacity while maintaining the granulation of the grinding process are carried out to maximize the use of the hammer mill machine, which is the second largest electric energy consumption in a plant. The method that can be done to achieve this is by setting the screen position and setting the right blower opening. Standard screen specifications will maximize the capacity of the grinding process and produce optimum granulation. In order to get the maximum grinding capacity, DFCO can be set at the maximum but will have an effect on the motor current during the grinding process, the average current will tend to be high. The aim of this research was to determine the effect of variations in the screen’s and blower’s position settings on the capacity and granulation of raw materials from the grinding process. The usage of 2.5 mm and 3 mm diameters screens, as well as adjusting the screen position of 2.5 mm at the top and 3 mm at the bottom, resulted in better capacity and granulation than using a screen with only 3 mm diameter. The larger the blower and DFCO openings, the greater the grinding capacity, but also increased the motor current. The larger the blower opening, the greater the decrease in the water content of grinding raw materials.

Multiple-output dc–dc converters are compact and cost effective as compared to multiple parallel dc–dc converters. This article focuses on a coupled-inductor single-input dual-output (CI-SIDO) buck converter. For the CI-SIDO converter, achieving independent regulation of output voltages and maintaining good dynamic performance are difficult due to cross-regulation and cross-coupling problems. In addition, tuning of controller parameters is challenging. Thus, this article proposes a decoupled average current control (ACC) to suppress cross-coupling and cross-regulation in CI-SIDO buck. It also demonstrates the method of decoupling of inductor currents and the stability issue that exists in ACC of CI-SIDO buck. The analysis shows that decoupling of inductor currents makes the design of controllers independent and simplifies the closed-loop transfer functions. Based on the conditions of decoupling and stability, a systematic design procedure for a Type-II compensator is developed. The proposed control method is compared with the voltage-mode control by using MATLAB/Simulink results. The comparison shows that the proposed ACC exhibits better dynamic performance. Finally, the proposed method is validated using experimental results.

This article proposes a new single-stage high-frequency-link based single-phase solid-state transformer (SST) topology. Switching tube multiplexing is carried out to reduce the number of switching devices and the corresponding modulation strategy is given. An optimized hybrid control analysis for reducing the average conduction current of insulated gate bipolar transistor (IGBT) and inductor was performed. By switching different control modes, the average current value of the SST inductor is kept being the minimum so as to reduce the conduction losses of IGBTs in the SST. As the core unit of the SST is the dual active bridge converter, the proposed optimal control is based on the extended phase-shift control, instead of triple-phase-shift control, that makes the implementation method very simple. And the feasibility of topology and optimized hybrid control scheme is verified through experiments.

Fretting corrosion at the head-neck taper junction was compared between silicon nitride (Si3 N4 ) and commercially available cobalt chrome (CoCrMo) femoral heads on titanium (Ti-6Al-4V) trunnions. An electrochemical setup was used to capture the fretting currents (characterized by oxide abrasion and repassivation) during cyclic loading. Onset load, pull-off force (disassembly load), short term and long term (1 million cycles) fretting currents were used to compare the fretting corrosion performance between the test group (Si3 N4 /Ti-6Al-4V) and the control group (CoCrMo/Ti-6Al-4V). Incremental cyclic fretting corrosion tests showed that the Si3 N4 /Ti-6Al-4V combination had statistically lower (P

The article presents the research of bioelectricity generation by electro-biosystems with mosses in containers with a soil substrate and a graphite-Zn-steel system of electrodes on green roofs during the autumn-winter-spring period. It is revealed that the optimum conditions for the functioning of electro-biosystems is the temperature above +10°С with simultaneous regular humidification of the soil. In these conditions, an average current of 19.50 mA was recorded. Electro-biosystems react by lowering in the level of produced bioelectric potential and current strength at temperature drops below 10°C, and in particular at frosts, and also, in the long absence of atmospheric precipitation. Electro-biosystems with mosses to varying degrees survived the winter period: in a significant part of them, connections between the electrodes was damaged due to the effect of frozen water or/and freezing of plants. The most optimal configuration of the electrode system for generating bioelectricity, which functions at the initial level after winter time, is established. Thermo-insulated electro-biosystems with mosses under the conditions of regular humidification have prospects of their use on green roofs of buildings after general increase of the generated bioelectric potential and current strength.

In this study, the visualization of the flow inside a Taylor cone formed during an electrohydrodynamic (EHD) spraying is conducted to analyze its stability among five liquid candidates. A micro-PIV with a micro-nozzle is used for the visualization, and the physical properties as well as measured values are utilized in the analysis. First, in forming the Taylor cone, the electrohydrodynamic force is required to be sufficiently large in order to overcome the surface tension of the liquid. Thus, among the five liquids tested here, three, in this case IPA, EtOH, and MeOH, form a Taylor cone due to the relatively low surface tension levels as compared to the others. Once electrohydrodynamic jetting occurs, the average and maximum velocities become monotonically proportional to the average current. As the velocities are the smallest in using IPA, the circulation flow becomes superior to the extrusive flow, which yields the stable formation of a Taylor cone. Also, low fluctuation of the instantaneous currents supports the stable formation of IPA. Consequently, IPA shows the most stable formation of the Taylor cone in our condition due to the lowest average current and low-level surface tension. Eventually, micro-PIV would be a good tool in choosing an optimal fluid for stable EHD spraying.

Phase imbalance (i.e., load imbalance among the three phases) causes inefficient use of three-phase distribution assets, resulting in additional reinforcement costs (ARCs) compared to if the three phases were balanced. However, two problems remain unresolved when calculating the ARC: 1) previous ARC formulas assume that the three-phase total peak and the single-phase peak current occur simultaneously, thus causing an underestimation of the ARC; and 2) previous formulas calculate ARC as a point value, using one year's peak load. However, the point value is not credible in supporting making investment decisions on phase balancing. This is because the growth of the yearly peak load is inconsistent over the years – the growth could be positive or negative over the years for low voltage (415 V, LV) networks. To address the above problems, this paper originally develops 1) an updated ARC formula; and 2) a customised approach, named as the cluster-wise probability assessment, to deliver a distribution and confidence range of ARCs for any given LV network. This approach only requires the yearly average current and single-phase peak current, making it applicable to the majority of the LV networks that have a minimal amount of data. Case studies also identify a counterintuitive finding of how the yearly single-phase peak current and the yearly average phase current impact the ARCs.

In order to develop renewable energy, it also needs to enhance the developing of supporting elements. For example, lithium-ion batteries as a component of energy storage. Lithium-ion batteries (Li-ion) have been chosen as energy storage devices for portable equipment, unmanned Aerial Vehicle (UAV) and grid storage systems. But there is a problem such as the process of charging the battery for UAV. Conventional converters used in those chargers have disadvantages such as limited power, lower voltage gain and also high current stress. Therefore, such converters are not efficient to be used for charging the battery. This paper proposes a cascaded bidirectional buck-boost converter for charging the battery. This converter can be operated bidirectional and have better rated power and higher voltage gain. Also, this topology has the same polarity with the input. From the test results, the converter can work in either forward or backward power flow. This converter is working in both buck or boost mode and has an efficiency of 83% in buck mode and 81% for boost mode. The charging process is about 83 minutes until SOC approximately 90 – 95.Keywords: battery charger, cascaded bidirectional buck – boost converter, constant current, li-ion introduction.

This The use of floating photovoltaics is increasingly attractive and has become a concern. This is due to the consideration that the surface temperature of the photovoltaic influences the voltage and current output. The study was carried out using two units of 50 Wp photovoltaic, one of which was placed on the mainland and floating in the pond. From the test results, it is found that floating photovoltaic has a higher output compared to the output of photovoltaic on land with an average voltage difference of 1.04%, an average current difference of 1.08%, an average real power difference of 1.12%, and an average efficiency difference of 1.29%.

Background: In transcranial direct current stimulation (tDCS), the injected current becomes distributed across the brain areas. The objective is to stimulate the target region of interest (ROI) while minimizing the current in non-target ROIs (the ‘focality’ of tDCS). For this purpose, determining the appropriate current dose for an individual is difficult. Aim: To introduce a dose–target determination index (DTDI) to quantify the focality of tDCS and examine the dose–focality relationship in three different populations. Method: Here, we extended our previous toolbox i-SATA to the MNI reference space. After a tDCS montage is simulated for a current dose, the i-SATA(MNI) computes the average (over voxels) current density for every region in the brain. DTDI is the ratio of the average current density at the target ROI to the ROI with a maximum value (the peak region). Ideally, target ROI should be the peak region, so DTDI shall range from 0 to 1. The higher the value, the better the dose. We estimated the variation of DTDI within and across individuals using T1-weighted brain images of 45 males and females distributed equally across three age groups: (a) young adults (20 ≤ x ˂ 40 years), (b) mid adults (40 ≤ x ˂ 60 years), and (c) older adults (60 ≤ x ˂ 80 years). DTDI’s were evaluated for the frontal montage with electrodes at F3 and the right supraorbital for three current doses of 1 mA, 2 mA, and 3 mA, with the target ROI at the left middle frontal gyrus. Result: As the dose is incremented, DTDI may show (a) increase, (b) decrease, and (c) no change across the individuals depending on the relationship (nonlinear or linear) between the injected tDCS current and the distribution of current density in the target ROI. The nonlinearity is predominant in older adults with a decrease in focality. The decline is stronger in males. Higher current dose at older age can enhance the focality of stimulation. Conclusion: DTDI provides information on which tDCS current dose will optimize the focality of stimulation. The recommended DTDI dose should be prioritized based on the age (&gt, 40 years) and sex (especially for males) of an individual. The toolbox i-SATA(MNI) is freely available.

The charging time of Li-ion batteries connected in series (LBCSs) power supply is the main concern in an electromagnetic propulsion system. However, the capacity loss of a Li-ion battery is inevitable due to the repetitive operation of LBCSs power supply, which leads to the decrease in the average current. Thus, the voltages of symmetrically distributed pulse capacitors of LBCSs power supply will not reach the setting value in the specified time. This paper proposes a novel closed-loop control method to solve the problem. By collecting the pulse capacitor voltage and the circuit current, the time sequences of Li-ion batteries are recalculated in real time in a closed-loop to increase the average current. The time-domain model of the circuit topology of the LBCSs power supply and an innovative closed-loop control method based on the time sequences recalculation algorithm are described first. Then, the circuit model is built in PSIM for simulation analyses. Finally, a series of experiments are conducted to confirm the effectiveness of the method on the megawatt LBCSs power supply platform. Both the simulation and experimental results validate that the proposed method not only shortens the charging time, but also increases the average current. In practical experiments, the charging time is shortened by 4.5% and the average current is increased by 4.8% using the proposed method at the capacity loss of 50 V.

This paper analyzes the high-performance efficiency of atomized electric discharge machining (EDM) ablation using quantitative analysis of discharge and combustion erosion. Using an argon-atomizing medium and an oxygen-atomizing medium, a comparative experiment is performed to calculate the amount of material erosion generated by discharge and combustion during EDM ablation. Then, by collecting the single-pulse discharge waveform and the discharge rate, comparative experiments are carried out between EDM and EDM ablation to study the influence of electrical parameters on the ratio of discharge to combustion erosion in EDM ablation process. The reasons for the efficiency of EDM ablation are determined to be the higher discharge probability when compared to conventional EDM and the introduced oxygen which reacts with the activated material, increasing combustion effectiveness. The results show that under different pulse width, pulse interval, and average current experimental conditions, the combustion erosion in the atomization ablation process accounts for 67–78% of the total erosion, and the efficiency of atomization EDM ablation is over 8 times that of traditional EDM.

Background Higher tDCS current may putatively enhance efficacy, with tolerability the perceived limiting factor. Objective We designed and validated electrodes and an adaptive controller to provide tDCS up to 4 mA, while managing tolerability. The adaptive 4 mA controller included incremental ramp up, impedance-based current limits, and a Relax-mode where current is transiently decreased. Relax-mode was automatically activated by self-report VAS-pain score >5 and in some conditions by a Relax-button available to participants. Methods In a parallel-group participant-blind design with 50 healthy subjects, we used specialized electrodes to administer 3 daily session of tDCS for 11 min, with a lexical decision task as a distractor, in 5 study conditions: adaptive 4 mA, adaptive 4 mA with Relax-button, adaptive 4 mA with historical-Relax-button, 2 mA, and sham. A tablet-based stimulator with a participant interface regularly queried VAS pain score and also limited current based on impedance and tolerability. An Abort-button provided in all conditions stopped stimulation. In the adaptive 4 mA with Relax-button and adaptive 4 mA with historical-Relax-button conditions, participants could trigger a Relax-mode ad libitum, in the latter case with incrementally longer current reductions. Primary outcome was the average current delivered during each session, VAS pain score, and adverse event questionnaires. Current delivered was analyzed either excluding or including dropouts who activated Abort (scored as 0 current). Results There were two dropouts each in the adaptive 4 mA and sham conditions. Resistance based current attenuation was rarely activated, with few automatic VAS pain score triggered relax-modes. In conditions with Relax-button option, there were significant activations often irrespective of VAS pain score. Including dropouts, current across conditions were significantly different from each other with maximum current delivered during adaptive 4 mA with Relax-button. Excluding dropouts, maximum current was delivered with adaptive 4 mA. VAS pain score and adverse events for the sham was only significantly lower than the adaptive 4 mA with Relax-button and adaptive 4 mA with historical-Relax-button. There was no difference in VAS pain score or adverse events between 2 mA and adaptive 4 mA. Conclusions Provided specific electrodes and controllers, adaptive 4 mA tDCS is tolerated and effectively blinded, with acceptability likely higher in a clinical population and absence of regular querying. Indeed, presenting participants with overt controls increases rumination on sensation.

In this work, the average current nodal expansion method was developed for the time-dependent neutronic simulation of transients in a nuclear reactor's core. For this purpose, an adopted iterative algorithm was proposed for solving the 3-D time-dependent neutron diffusion equation. In the average current nodal expansion method, the domain of the reactor core can be modeled by coarse meshes for neutronic calculation associated with reasonable precision of results. The discretization of time differential terms in the time-dependent equations was fulfilled, according to the implicit scheme. The proposed strategy was implemented in some kinetic problems including an infinite slab reactor, TWIGL 2-D seed-blanket reactor, and 3-D LMW LWR. At first, the steady-state solution was carried out for each test case, and then, the dynamic neutronic calculation was performed during the time for a specified transient scenario. Obtained results of static and dynamic solutions were verified in comparison with well-known references. Results can indicate the ability of the developed calculator to simulate transients in a nuclear reactor's core.

This paper introduces a novel H-bridge structured ac–ac pulsewidth modulation (PWM) converter topology based on two-level non-differential ac chopper legs, which can work at the non-inverting and inverting modes for the utility voltage compensation. Compared to the traditional bipolar-type H-bridge ac–ac converter, no bidirectional switches are switched in a complementary manner to overcome the commutation problem due to the delayed response of electronic circuits and semiconductor switching devices. The detailed PWM control signals and operational principles are presented to regulate the output voltage in a bipolar manner. Especially the main advantage is that the proposed ac–ac converter has the same buck/boost operation process for non-inverting and inverting modes, which ensures the continuously average current supply to the low-voltage output side without a high-value capacitor to support power. Additionally, due to the common sharing ground of the input and output, the feature that output can reverse or maintain phase angle with input is supported well. Then, the detailed analysis, design conditions, and experimental verification based on a 1 kW experimental prototype are presented.

In the province of Van, wheat cultivation has made in the 787 314 da area, and in return has produced 104 44 thousand tons of production and has obtained 132 6 kg/da yield. This corresponds to half of the yield in Turkey (280 kg/da). If the yield in te province can be increased to average of Turkey,the same production would be possible to produce in half amount of area. The main reason for the decrease in productivity in province is the use of local varieties instead of high-efficiency and high quality registered varieties in wheat agriculture. Since the local varieties has not preferred in the flour industry, the sector supplies 80% of the raw material needed from outside the province. However, very fragmented and small-scale agricultural business structure, tractors and equipment is lower than Turkey's average current, the plurality of fallow fields, such as technical information and material deficiency in production of some problems, is seen as the obstacles of wheat cultivation in the province. Some measures to be taken in order to eliminate these obstacles and increase the yield and quality will result that every relevant sector can be satisfied in wheat production.

Security-centric components and systems, such as System-on-Chip early-boot communication protocols and ultra-specific lightweight devices, require a departure from minimalist design constructs. The need for built-in protection mechanisms, at all levels of design, is paramount to providing cost-effective, efficient, secure systems. In this work, Securely derived Finite State Machines (S*FSM) and power-aware S*FSM are proposed and studied. Overall results show that to provide an S*FSM, the typical FSM requires a 50% increase in the number of states and a 57% increase in the number of product terms needed to define the state transitions. These increases translate to a minimum encoding space increase of 70%, raising the average encoding length from 4.8 bits to 7.9 bits. When factoring in relaxed structural constraints for power and space mitigation, the respective increases of 53 and 67% raise the average number of bits needed to 7.3 and 7.9. Regarding power savings, current minimisation is possible for both FSMs and S*FSMs through the addition of encoding constraints with average current reductions of 30 and 70%, respectively. Overall, a power-constrained S*FSM consumes about 5% more power than insecure FSMs with binary encodings, though with a penalty of a 95% increase in layout area.

The effect of pulsing parameters on the metal and heat transfer behaviors in pulsed gas metal arc welding is investigated by a numerical model based on the solution of the magnetohydrodynamic equations within the framework of phase field method. Five sets of current waveforms using different peak current and duration (i.e. 300 A-2.30 ms, 350 A-1.80 ms, 400 A-1.45 ms, 450 A-1.20 ms and 500 A-1.00 ms) but maintaining an identical average current (i.e. 170 A) are considered and compared. The pulses using higher current but shorter duration result in more elongated shape of the pendent drop, earlier detachment, and significantly higher velocity of the detached drop. Unlike the drop velocity, higher peak current merely leads to a slight increase in the average temperature of the detached drop. The reason for this slight increase is that only the joule heating increases with the peak current, while the sheath heating and arc heating is governed by the average current and keeps almost constant using different pulsing parameters. The simulation results are compared with the high speed photos and exhibit good agreements.

It is of great importance for multi-terminal DC (MTDC) system to immediately isolate the DC fault line within several milliseconds after DC fault due to VSC or half-bridge based MMC converters with limited ability to control DC fault current during DC fault. Failing of the DC fault isolation during “ Capacitor Discharging Stage ” may lead to the overall MTDC system out of operation with the fast blocking of IGBTs. Therefore, initial DC fault current analysis is essential for system protection design, especially for fault detection. Accordingly, a transient simplified model is first proposed with only high-frequency components of the fault DC network reserved. As a result, the original complex DC network is largely reduced and the fault DC current with several milliseconds can be clearly expressed based on the proposed model. According to the distinct differences between the current of faulty cable and that of healthy cable, a non-unit DC fault detection method utilizing the transient average value of line current with low computational complexity and high-sensitivity is further proposed. Numerical simulations based on PSCAD/EMTDC have been carried out, which well-demonstrate the accuracy of the proposed transient simplified model for initial DC fault analysis and the effectiveness of the proposed transient average current based fault detection scheme. Compared with the traditional change of rate of current based protection method, the proposed one stands out for relatively low sampling frequency, high fault resistance tolerant ability, and robustness against outside noise and data missing.

China's first Mars rover Zhurong has successfully began its exploration on Mars surface. It is important to estimate the rover slip while driving on the Mars, for the slip has a negative impact on the navigation accuracy and passing safety. In this paper, we establish the slip estimation model by BP and GA-BP algorithm for Zhurong rover. Pitch and roll of the rover, average current and velocity of the wheel drive motors are selected as input features to train the model. All data are obtained by Zhurong validator's indoor slip experiment. The results demonstrate that genetic algorithm effectively optimizes the weights and thresholds of the BP network, so that GA-BP performs better than the BP neural network in rover slip estimation. The GA-BP model established in this paper has reference value for the slip estimation of Zhurong rover.