Conventional Discharge Research Articles

Optimal coordinated energy management strategy for standalone solar photovoltaic system with hybrid energy storage

Energy storage devices and renewable resources, especially rooftop photovoltaic (PV), are vital to the operation of standalone systems. In this study, an energy management strategy (EMS) for battery energy storage systems (BESS), PV, and supercapacitors (SC) is presented. The proposed control strategy is designed to optimize the BESS flow rate, discharge, and charge cycles of the energy system using the Meta-heuristic Jaya algorithm by properly coordinating SC and PV. SC is employed in HESS to fulfill the transient energy mismatches and reduce the transitory high charge/discharge current rate impacts on BESS using EMS. The proposed controller also has the benefit of keeping the battery's SoC within limitations for a long period. To extend the life of BESS, the EMS is aimed at minimizing deep charging and discharging by reducing PV generation, particularly under light load (no-load) situations and when battery and SC's SoC≥SoCmax or charging. Similarly, the optional load shedding is employed when battery and SC's SoC≤SoCmin to avoid deep discharge. The proposed EMS is validated in both simulation environment and hardware-prototype under different perturbations and operating conditions. The charge and discharge rate performance of BESS and SC under different charge and discharge time durations, i.e., 1 s, 2 s, and 3 s, were evaluated in both simulation and hardware, and compared to conventional charge and discharge methods for HESS, whose charge and discharge time durations are nearly 0.3 s to 0.4 s. As a result, battery stress is significantly reduced. Furthermore, the economic analysis of the complete system is carried out. In this, it is observed that standalone PV and HESS systems with the proposed EMS are cost-effective and economical compared with PV and BESS systems when operated for a long horizon beyond 6 years.

Impact of self-sputtering in high power impulse magnetron sputtering (HiPIMS) with helium

Conventional magnetron discharge is a widely used technology for many applications. In the last decade, the high current density sputtering regime has been an interesting alternative for tailoring thin film properties. In this paper, we focused on the electrical characterization of the helium magnetron plasma operated at average gas pressure (5 Pa) with a molybdenum target. Optical emission spectroscopy diagnostics also supports this study by providing information on electron density evolution. The analysis of the plasma–surface interaction zone on the target unveiled the physical mechanisms associated with the high current density range (6 A cm−2), corresponding to different discharge regimes. The self-sputtering yield plays a key role in high-power impulse magnetron sputtering discharge operated with helium. The electron density is highly dependent on the presence of a metal.

Effect of multi-channel discharge distribution on surface homogeneity in super-high-thickness WEDM

The multi-channel discharge phenomenon for super-high-thickness (more than 1000 mm) cutting is studied in high-speed wire electrical discharge machining (HS-WEDM). In super-high-thickness cutting, the length of the wire electrode with a poor conductor is longer in the machining area, so the resistance of wire electrode cannot be ignored. It is found that the main reason for the formation of multi-channel discharge is that there is a high voltage between electrodes after dielectric breakdown due to the resistance characteristics of the wire electrode. When the conventional discharge circuit is used for machining, the voltage between electrodes in the middle of the workpiece is much higher than that at the upper and lower ends, which is easier to generate multi-channel discharge. Multi-channel discharge has the characteristic of dispersing discharge energy, which results in inhomogeneous surface roughness on the whole section of the workpiece. To improve the distribution characteristics of the inter-electrode voltage after dielectric breakdown, a novel discharge circuit is proposed, which gradually increases the inter-electrode voltage of discharge points distributed along the thickness direction of the workpiece, and significantly improves the formation probability of multi-channel discharge on the whole cutting surface. A super-high-thickness workpiece with a thickness of 1000 mm is used for continuous cutting. The cutting speed of the two types of discharge circuit is basically the same. But the surface roughness machined by the rear-end parallel circuit is reduced by 15.8%, and the surface homogeneity is greatly improved.

Fading analyses of commercial lithium-ion batteries with blended cathodes using synchrotron X-ray diffraction measurement and discharge curve analysis

We investigated the fading behavior of commercial lithium-ion batteries with blended cathodes. Synchrotron X-ray diffraction measurements revealed the constituent materials of the blended cathode and the degradation state of the cathode due to particle cracking. A particle model was newly introduced to the discharge curve analysis in order to explain the voltage change due to particle cracking, which is not considered in the conventional discharge curve analyses. Herein, blended cathode and particle models to advance the conventional discharge curve analyses have been presented. We have implemented these models besides basic model within our discharge curve analysis code called VOLCALO (VOLtage CALculation and Optimization). The blended cathode model could reproduce the measured values of the discharge curve of cycled batteries better than the conventional method and obtain a change in blend weight ratio due to degradation. The particle model analysis revealed that considering the particle size change due to particle cracking, changes in the discharge curves near the discharge end could be explained by the increase of surface sites.

Mechanical Understanding of Li–CO2 Batteries: The Critical Role of Forming Intermediate *Li2O

The emerging Li-CO2 batteries are considered a promising next-generation power system because they can fix CO2 while storing energy; however, their underlying mechanism remains elusive, impeding their efficient development. Meanwhile, apart from the conventional discharge product Li2CO3, the unexpected Li2O species has also been detected, but its formation process is thus far undecided. Here, we report a new mechanism for Li-CO2 batteries using first-principles calculations, which explains the long-standing puzzles. We show that such a process can be divided into two stages: (I) forming intermediate *Li2C2O4 via surface lithiation and (II) generating -Li2CO3 and C through a *Li2O-mediated pathway. We discover that the major kinetic barrier occurs in the coupling of *Li2CO2 and CO2 in the first stage. Especially, in the second stage, *CO produced from *Li2C2O4 decomposition is preferentially lithiated to *LiOC rather than disproportionated, and then *LiOC can be further lithiated to intermediate *Li2O after C nucleation, which contributes to the final formation of Li2CO3 in the presence of sufficient CO2.

Optimization of overshoot in the pulsed radio frequency inductively coupled argon plasma by step waveform modulation

The pulsed inductively coupled plasma (ICP) has considerable potential to satisfy multiple stringent scaling requirements for use in the semiconductor industry. However, overshoot of plasma parameters during the rising period of the pulse affects the stability and uniformity of the plasma and can lead to a breakdown of the wafer and over-sputtering of the film. In this study, a step waveform modulation method is used to reduce the overshoot at the initial stage of the pulse. The behavior of the discharge is monitored by measuring (i) the modulated step waveform signal on the function generator, (ii) the input power (by a time-resolved VI-probe), and (iii) the amplitudes of the coil voltage and current (by voltage and current probes, respectively), as well as (iv) the plasma parameters including the electron density, the effective electron temperature, and the electron energy probability distribution function (by a time-resolved Langmuir probe). It was found that the state of the plasma can be controlled by changing the waveform, such as varying the time of the rising edge, varying the initial amplitude, and varying the duration of the low-high amplitude. The results indicated that the overshoot value of the electron density can be reduced by using a low-high step waveform. When the amplitude of the waveform was 500/550 mV and the duration was 200/300 μs, the overshoot value observed was 1/4 of that of the conventional ICP pulse discharge. In addition, increasing the duty cycle of the pulse could also reduce the overshoot value due to the high electron density that occurs during the afterglow period. Moreover, the plasma can reach a steady state more quickly at high pressure by using a step waveform of high amplitude.

Electrical properties of adhesives designed for smart debonding by a pulsed discharge method

ABSTRACT Facile techniques are required for the debonding of polymeric adhesives from metals for material recycling. A promising solution is a pulsed discharge debonding method. In this approach, a pulsed discharge with a high voltage is applied to the system over a short time. Rapid expansion of gasified materials and shock-wave emissions are produced from the discharge passage, which results in debonding. A drawback of the conventional pulsed discharge method is that it must be conducted in water, otherwise, the pulsed discharge creeps along the material surface without destroying the adhesion. In this study, filler was added to the structure adhesive for the effective pulsed discharge debonding of metal adherend. Epoxy resins with fillers of carbon black, copper and barium titanate particles were fabricated, and their properties and adhesive strength before and after application of the pulsed discharge were investigated. We succeeded in introducing the pulsed discharge inside the adhesive by adding 3.4 vol% of carbon black to the epoxy adhesive; the rapid expansion of gasified adhesion that was caused by the discharge, resulted in debonding. The threshold volume fraction of carbon black for effective pulsed discharge inside the adhesive was discussed based on the percolation model with experimental data.

Design of a multistage hybrid desalination process for brine management and maximum water recovery.

Hypersaline brine production from desalination plants causes huge environmental stress due to the untenable conventional discharge strategies. Particularly, brine production is expected to drastically increase in the coming few decades due to the increasing desalination capacity in attempts of forestalling water scarcity. Thereby, zero liquid discharge (ZLD) is a worth-considering solution for strategic brine management. ZLD or minimal liquid discharge (MLD) systems provide maximum water recovery with least or zero liquid waste generation and valuable salt production. In this work, a theoretical design of ZLD/MLD system is proposed for reverse osmosis (RO) brine management. Different scenarios are investigated utilizing multistage freeze desalination (FD) and its hybridization with multistage direct contact membrane distillation (DCMD), and eutectic freeze crystallization (EFC) technologies. The design is based on the experimental assessment of the indirect FD process at different feed salinities, i.e., 2g/L to 155g/L. FD experiments showed that ice quality is reduced at greater crystallinity levels and initial concentration. Moreover, a computational fluid dynamics (CFD) model is utilized to assess the performance of DCMD. A single DCMD module could produce 53kg/(m2.h) of pure water operating with 69% thermal efficiency. Eventually, water recovery, water quality, as well as specific energy consumption (SEC) are evaluated for the whole system. Based on different configurations of the hybrid ZLD system, the proposed design can achieve water recovery between 40 and 93% with SEC range of 28-114 kWh/m3. Results also showed that the produced water quality exceeds drinkable water standards ( 500mg/L). This work has provided great evidence in the practicality of ZLD/MLD systems for sustainable brine management.

Effect of dual-core spark discharge on ignition probability and engine power

This report presents the experimental study of developing a dual-core spark discharge (2C-SD) model for clean combustion. We first studied ignition probability (Pig) of lean methane/air at an equivalence ratio of 0.5 using 2C-SD with different spark-gaps (dgap = 1.0mm and 2.0mm) in a constant volume combustion chamber. We then applied 2C-SD to the engine driving a 2.5-kW generator. The results indicated that Pig is 30% and 45% at dgap=1.0mm and 2.0mm, respectively, while Pig is 0 when using conventional single spark discharge (CSSD). Compared to CSSD, when using 2C-SD the engine power could be improved by 4%-9.7%, depending on the throttle openings. We expect the larger volume of the initial flame kernel by 2C-SD could enhance Pig and quickly reach the critical flame radius before self-sustained propagating. The faster initial flame speed is essential for achieving the optimal combustion phasing, resulting in a higher power.

Flow control performance evaluation of a tri-electrode sliding discharge plasma actuator

Tri-electrode sliding discharge (TED) plasma actuators are formed by adding a direct current (DC) exposed electrode to conventional dielectric barrier discharge (DBD) plasma actuators. There are three TED modes depending on the polarity and amplitude of the DC supply: DBD discharge, extended discharge and sliding discharge. This paper evaluates the electrical, aerodynamic and mechanical characteristics of a TED plasma actuator based on energy analysis, particle image velocimetry experiments and calculations using the Navier–Stokes equation. The flow control performances of different discharge modes are quantitatively analyzed based on characteristic parameters. The results show that flow control performance in both extended discharge and sliding discharge is more significant than that of DBD, mainly because of the significantly higher (up to 141%) body force of TED compared with DBD. However, conductivity loss is the primary power loss caused by the DC polarity for TED discharge. Therefore, power consumption can be reduced by optimizing the dielectric material and thickness, thus improving the flow control performance of plasma actuators.

Wheel wear behavior and its influence on grinding performance in electrical discharge diamond grinding of reaction-bonded silicon carbide

Diamond wheel wear is the greatest challenge for the high-efficiency grinding of SiC mirrors due to the need for the frequent dressing of the wheel. To realize the dressing of the diamond wheel in the process, the electrical discharge diamond grinding (EDDG) that combines conventional grinding (CG) and electrical discharge machining (EDM) was used to machine the mirror material of reaction-bonded silicon carbide (RB-SiC) considering its conductivity. However, the diamond wheel will experience quite different wear behaviors from those in the CG process due to the additional electrical discharge action in the EDDG process. As a result, different grinding performances will also be obtained. In this paper, the wheel wear behavior and its influence on grinding performance were investigated by a comparing test with the CG process in continuous EDDG of RB-SiC. The wear behavior and mechanism of the diamond wheel were investigated by a combination of morphology detection and spectra analysis. To explore the influence of wheel wear on grinding performance, the material removal rate (MRR), grinding ratio (GR), grinding force, and surface roughness were discussed based on the wear regulation of the diamond wheel varied with processing time. The result revealed that the electrical erosion was mainly responsible for the different wear behaviors and mechanisms of the diamond wheel in the EDDG process. Due to the dressing effect and material removal caused by discharge sparks, higher MRR, lower GR, lower grinding force, and lower surface roughness were obtained in the EDDG process.

Influence of Cryogenic Behaviour on Copper Electrode for Non-Conventional EDM

In the last few decades, non-traditional machining has increased the efficiency of the machining process. One of the most prevalent non-traditional methods of milling is through the use of an EDM process. Traditional machining methods can't easily machine materials with a complicated profile or hardness that EDM can handle. The industrial sector makes extensive use of EDM. Cryogenically treated copper electrodes and regular copper electrodes were used to conduct an experiment on an EN24 material using varied input parameters, such as electrode rotation, gap voltage, and discharge current. Electric discharge machining was used in a study. The Taguchi method is used to design experiments. Three input parameters were employed in an orthogonal L16 array to find an optimal value for each of the three components. OC (overcut), TWR (Tool wear rate), and Ra (surface roughness) are the three output variables. The S/N ratio can be used to determine the best values and relative relevance of each of these factors using a statistical analysis of variance (ANOVA) table. Additionally, the overcut, tool wear rate, and surface roughness of traditional and non-traditional EDM are examined. For the deep cryogenic and non-traditional machining method, conventional and non-traditional electric discharge machining methods were found to have optimal or dominant factors for the TWR and Ra.

Driving range evaluation based on different cabin thermal management goals of CO2 heat pumps for electric vehicles

Improving driving range is very important for electric vehicles (EVs). The use of CO2 heat pumps to replace Positive Temperature Coefficient (PTC) heaters for cabin heating is one of the most efficient choices for improving driving range in EVs. The combination of CO2 heat pumps and electric vehicles matches well with the social requirements of low-carbon, cleaner production, and sustainable development. However, heat pumps may frost under a conventional optimal discharge pressure control, resulting in a rapid drop in driving range. To solve this problem, the impact of frost on the driving range under different ambient conditions was assessed, and the failure of performance guarantee under conventional control in frost-prone conditions was deeply studied. Based on the experimental data, a heating capacity decline map was developed, and a new global performance improvement control method was proposed. Moreover, the dynamic characteristics between optimal discharge pressure control and the new control process were experimentally compared. Furthermore, a comparative analysis of driving range improvement under the global performance improvement control was carried out in three cities with typical climates. The results indicated that driving range improvement of the new method could be even as high as 10% in some conditions. Finally, the global performance improvement control method was recommended in regions with low ambient temperatures and high humidity.

Experimental Study on the Working Characteristics of Tri-Electrode Plasma Actuator Utilizing a Combination of Corona and Barrier Discharges

A tri-electrode plasma actuator (TED-PA), which has an additional electrode with a DC voltage, induces jets from two facing electrodes and achieves larger thrust and higher efficiency than a conventional dielectric barrier discharge plasma actuator. However, there are problems such as the large potential difference between the exposed electrodes, which can cause sparks and device destruction. Therefore, it is necessary to clarify the working mechanism of TED-PAs and optimize their configuration and applied voltage. In this study, we obtained the discharge photograph, the thrust, and the flow velocity field and investigated the characteristics of the DC voltage and the frequency of the AC voltage. To isolate the effects of the discharge from the potential variation, a corona discharge plasma actuator and a TED-PA were compared. As a result, increasing the frequency of the AC voltage induced stronger jets from the AC and DC electrodes. This result indicates that the barrier discharge enhances the jet from the DC electrode without changing the potential difference between the electrodes.

Ignition kernel development in a reactive flow for nanosecond-pulsed high-frequency and DC arc discharges

The development of energy efficient combustion systems is a critical technical objective in the engine and power generation industries. This pursuit often prompts using conditions at the limits of capability, dictating the need to expand the envelope of robust and reliable operation. Nanosecond-pulsed high-frequency discharges (NPHFD) have proven to be effective in extending ignition limits in both quiescent and flowing environments. However, limited research has been conducted comparing the kernel growth behavior in a flowing environment of a train of discrete nanosecond discharges to that of a conventional DC arc discharge. Therefore, this work focused on comparing these two types of discharges by matching the total energy deposited, total deposition time, and average power. For each system, three average power conditions (100, 180, and 400 W) were tested, each including five total discharge times (0.05, 0.15, 0.25, 0.50, and 1.00 ms) at two inter-electrode gap distances of 1 and 2 mm. The 1 mm gap distance results showed that the NPHFD system produced larger ignition kernel areas than the conventional system at the highest average power (therefore, highest pulsation frequency) setting. At all other average power conditions, the NPHFD system produced equivalent or smaller ignition kernels than the conventional system due to a lack of pulse-to-pulse coupling. At the 2 mm inter-electrode gap distance, the NPHFD ignition system produced larger kernels at all conditions except at the lowest average power and discharge duration setting. At the highest average power and longest discharge duration setting, the NPHFD kernel was nearly twice as large in area as the kernel produced by the conventional system at 5 ms after discharge. The larger kernel area created by the NPHFD system at the larger gap distance, higher average power, and longer total discharge duration conditions could be explained by the high level of pulse-to-pulse coupling and discharge-induced jetting behavior. The jetting behavior was a function of electrode polarity and mainly extended the reactive region of the kernel in the spanwise direction.

Impressions of Conventional Bedside Discharge Teaching Among Readmitted Heart Failure Patients.

The purpose of this project was to report patient impressions of discharge teaching delivered by nurses among a population of heart failure (HF) inpatients. Heart failure readmissions are frequently attributed to the quality of discharge teaching delivered by nurses. Thematic analysis, an atheoretical approach to the identification, organization, and analysis of themes in texts, was used to explore the data collected from patient interviews. Sixteen interviews were conducted with patients readmitted for HF on dedicated cardiac units. Six major themes were identified including: 1) recall of instructions; 2) comprehension; 3) teaching media; 4) follow-up; 5) role of caregivers; 6) mismatch between nurse and patient concerns; and 7) readmission stories. Discharge teaching could be improved by diminishing the volume of print materials distributed to HF patients, providing simple summaries of the most relevant advice, focusing on patient concerns more than the hospital agenda, and directly including home caregivers in teaching.

Using Noncontact Measurement of Water Surface Dynamics to Estimate River Discharge

AbstractEstimating river discharge requires simultaneous measurement of velocity and flow depth. While surface velocities are relatively easy to measure using noncontact techniques, depth measurement usually requires physically intrusive instrumentation. This limits our capability to remotely monitor discharge in natural rivers subject to bed level variations. This work tests the potential to estimate the surface velocity, the water depth, the depth average velocity, and then discharge of a river using only a sequence of images of the dynamic water surface. The method is based on a comparison between the spatiotemporal Fourier spectra of the pixel intensities of these images and the theoretical dispersion relations of turbulence‐generated surface fluctuations and gravity‐capillary waves. The method is validated through the analysis of water surface videos obtained with fixed cameras from two river sections equipped with conventional discharge gauging. The applicability of the approach is demonstrated and the measurement uncertainties are quantified. The method is affected by two main sources of uncertainty: one derives from the estimation of the velocity index and the other from the obtainable resolution of the Fourier analysis. This resolution strongly controls the observation of depth and/or velocity variations in space and in time. The technique has advantages over current approaches: it has clear physical foundations; the equipment is low cost and is highly mobile; it does not need artificial tracers or physical equipment to measure depth; and it can directly provide estimates of the key flow parameters just from time series of images of the water surface.

Electrical and aerodynamic characteristics of sliding discharge based on a microsecond pulsed plasma supply

Plasma flow control technology has broad prospects for application. Compared with conventional dielectric barrier discharge plasma actuators (DBD-PA), the sliding discharge plasma actuator (SD-PA) has the advantages of a large discharge area and a deflectable induced jet. To achieve the basic performance requirements of light weight, low cost, and high reliability required for UAV (Unmanned Aerial Vehicle) plasma flight experiments, this work designed a microsecond pulse plasma supply that can be used for sliding discharge plasma actuators. In this study, the topology of the primary circuit of the microsecond pulse supply is determined, the waveform of the output terminal of the microsecond pulse plasma supply is detected using the Simulink simulation platform, and the design of the actuation voltage, the pulse frequency modulation function and the construction of the hardware circuit are achieved. Using electrical diagnosis and flow field analysis, the actuation characteristics and flow characteristics of sliding discharge plasma under microsecond pulse actuation are studied, the optimal electrical actuation parameters and flow field characteristics are described.

Effect of Multimedia Health Education on Psychological Burden, Quality of Life Ability, and Self-Efficacy of Congenital Microtia.

Aims To investigate the effects of multimedia health education on psychological burden, quality of life, and self-efficacy of patients with congenital microtia. Materials and Methods Eighty cases of patients with congenital microtia treated and cared for in our hospital from June 2018 to June 2022 were selected according to the numerical table method as retrospective study subjects and divided into 40 cases each in the comparison group and the observation group. The comparison group implemented conventional health education and discharge instruction, and the observation group implemented multimedia health education care to compare the effects of self-efficacy, self-care ability and psychological burden of patients in the two groups. Results Before care, the two groups had no statistically significant difference in the quality of life scores (P > 0.05). Aftercare, the mental vitality scores, social interaction scores, emotional limitation scores, and mental status of patients in the observation group were significantly higher than those in the comparison group (P < 0.05). Before nursing care, there was no statistically significant difference in the nursing ability and anxiety-depression scores between the two groups (P > 0.05). After nursing care, the health knowledge level, self-care skills, self-care responsibility, and self-concept of the observation group were higher than the comparison group, while the depression-emotional disorder scores were significantly lower than the comparison group (P < 0.05). Conclusion Routine health education and discharge instruction combined with multimedia health education care can effectively improve the quality of life of patients with congenital microtia, reduce adverse emotions, and improve patients' sense of self-efficacy.

Effect of Kangaroo Mother Care on the Psychological Stress Response and Sleep Quality of Mothers With Premature Infants in the Neonatal Intensive Care Unit.

ObjectiveTo investigate the effect of kangaroo mother care on the psychological stress response and sleep quality of mothers with premature infants admitted to the neonatal intensive care unit (NICU).MethodsA randomized controlled design was used to recruit participants. The study recruited 126 mothers of premature infants in the NICU from January 2019 to January 2020. The participants were divided into the experimental and control groups according to the random number table method (63 mothers per group). The control group was managed with conventional premature infant treatment, nursing programme, and discharge education, whereas the experimental group was managed with a 4-week kangaroo mother care intervention. The psychological stress state and sleep status of mothers with preterm infants in both the groups were evaluated using the Symptom Check List 90 (SCL-90) and Assens Insomnia Scale (AIS).ResultsAfter the intervention, the total SCL-90 score and factor scores such as coercion, interpersonal relationships, depression, anxiety, hostility and additional factors, were lower in the experimental group than those in the control group (P < 0.05). The total AIS score and the items such as night waking, total sleep time, total sleep quality, daytime mood and daytime body function were lower in the experimental group than those in the control group (P < 0.05).ConclusionsThe Kangaroo mother care approach can relieve adverse psychological stress and improve the sleep status of mothers of NICU premature infants after mother-infant separation. It can be promoted and used in mothers of premature infants in the NICU to enhance physical and mental health.