Optimal Discharge Research Articles

The Dependence of Electrochemical Behavior and Discharge Performance on the Zn/Gd Ratio of Mg-Li-Zn-Gd Anodes for Mg-Air Batteries

In this study, the electrochemical performance and discharge behavior of Mg-Li-Zn-Gd alloys with α-Mg and β-Li-based anode material are investigated, with the aim to improve the anode performance of Mg-air batteries. The experimental anode alloys with detailed Mg-8Li-xZn-yGd (x = 1, 2, 3; y = 1, 2, 3 wt.%) components are prepared, and extrusion deformation is carried out on these alloys. Simultaneously, scanning electron microscope (SEM), X-ray diffractometer (XRD), electrochemical workstation, and constant current discharge systems are applied for microstructure characterization, corrosion, and discharge performance testing. The results show that the experimental alloys are composed of an α-Mg and β-Li dual matrix, with W-Mg3Gd2Zn3, Mg3Gd, and MgLiZn second phases. Meanwhile, extrusion deformation promotes the recrystallization process through the particle-induced nucleation mechanism. The corrosion resistance is improved with the increasing Zn/Gd ratio, and the extruded Mg-8Li-2Zn-1Gd (LZG821) alloy exhibits the optimum corrosion resistance, with a corrosion rate of 0.493 mm·year−1. In addition, the extruded Mg-8Li-1Zn-1Gd (LZG811) alloy has the optimal discharge performance, with a discharge specific capacity of 1371.04 mA·g−1 at a current density of 40 mA∙cm−2, and its anode efficiency reaches nearly 70%. The poorer discharge properties of the Mg-8Li-2Zn-1Gd (LZG821) and Mg-8Li-2Zn-3Gd (LZG823) alloys are attributed to their refined grains, which could bring severe intergranular corrosion while increasing the grain boundary density.

Generation of multiply charged metal ions in a high current short pulse vacuum arc

We have studied the plasma composition of a high current short pulse vacuum arc discharge with different cathode materials: lanthanum, gadolinium, lead, silver, and tin. We find that for optimal vacuum arc discharge parameters – arc current pulse duration about 2 μs and amplitude about 3 kA – the maximum ion charge state is 11+ and mean ion charge state from 7.8+ for tin to 9.6+ for lanthanum. The mean ion charge state for different materials depends on the discharge voltage and the energy required for ionization to maximum charge state. The cathode surface heats to a temperature of 700 °C–1100 °C in the course of the arc current pulse, depending on the cathode material, and the cathode surface of low melting point metals such as lead and tin melts to a depth of 5 μm and 10 μm, respectively. Surface melting does not lead to change in plasma ion composition, since the ion flux from the cathode considerably exceeds the evaporated atom flux.

Performance analysis and thermal comfort evaluation of a CO2 transcritical air-conditioning system for cabin thermal management of electric vehicles

This study investigates the effects of different operating conditions on system performance and optimal discharge pressure by establishing a numerical model of CO2 cabin thermal management system and validating the model with experimental data. Besides, two different optimal discharge pressure formulas are attained based on different parameters. It is found that the multi-parameter formula is more accurate than the other with a maximum deviation of 2.64%. Then, the control strategy is designed based on this formula to investigate the coupled effects of thermal comfort and economical performance under different driving patterns and different ambient temperatures. The elevation of PMV indicator can weaken the declining rate of power and energy consumption, enhance the driving range and reduce annual operation cost in cooling mode (AOCc) of vehicle. The boundary of thermal comfort zone (PMV = 0.5) exhibits excellent economical efficiency due to its higher growth rate of driving range (6.3%) and reduction rate of AOCc (7.9%) from 0 to 0.5 PMV at the ambient temperature of 35 °C. And this improvement is more prominent under higher ambient temperature.

Electrical discharge machining of super alloy incoloy 925: a study based on box behnken design and response surface methodology

Incoloy 925, a Nikel-based superalloy, exhibits low machinability with conventional machining techniques due to its inhomogeneous properties. Therefore, there is a need to establish a non-conventional method to efficiently machine this alloy. This work is a novel attempt to present the electric discharge machining (EDM) of the superalloy Incoloy 925 and subsequent multi-response optimization. The model for the analysis was designed using the Box Behnken Design (BBD) technique, and the Response Surface Methodology (RSM) was used for the optimization of the results. The machining was performed using a cylindrical copper tool of 11 mm diameter. The effect of pulse-on time (Ton), current, and pulse-off time (Toff) on the material removal rate (MRR), tool wear rate (TWR), and surface roughness (SR) was investigated. The results from variance analysis confirmed the significance of all the three input factors. The investigation revealed that the maximum MRR (99.2154 mm3/min) was obtained at a pulse-on time of 90 μs, pulse-off time of 5 μs, and current of 30 A. The minimum TWR (0.8866 mm3/min) were achieved at Ton = 60 μs, Toff = 8 μs and current = 10 A. The microscopic images of the machined surfaces revealed very few micro-voids and globules and no cracks, resulting in a fine surface finish of 1.2436 μm, achieved through optimal discharge energy transfer and copper electrodes. The optimal values MRR, TWR, and SR according to composite desirability function are 99.1524 mm3/min, 1.0915 mm3/min, and 1.3925 μm. The experimental results were accurately predicted using RSM and an artificial neural network (ANN), with the ANN showing a predicted correlation coefficient (R) close to 1 indicating high accuracy of the model.

Thermodynamic analysis of a modified two-stage transcritical CO2 refrigeration cycle with an ejector and a subcooler

In the application scope of large-scale supermarkets, the practicality of transcritical CO2 refrigeration device has been confirmed to be quite satisfying. A modified two-stage transcritical CO2 refrigeration cycle with an ejector and a subcooler (MTC) is proposed in this paper. In the modified cycle, the ejector recovers expansion works and reduces irreversible losses in the throttling process. The subcooler provides subcooling degree for the CO2 entering the low-temperature (LT) evaporator, thus increasing the refrigeration capacity and improving the COP of the modified cycle. Thermodynamic analysis has shown that the exergy efficiency (ηex) and COP of MTC under given operating condition has been enhanced by 13.7 % and 14.2 % compared to BTC. The discharge temperature at the outlet of high-pressure compressor in MTC is decreased by 8.3℃. Under typical operating condition, the optimal discharge pressure of MTC is 9.07 MPa, which is lower than that of BTC. The correlation to calculate optimal discharge pressure for single-stage CO2 refrigeration cycle is also suitable for MTC under given operating conditions. The MTC has also shown better performance under variable operating conditions. For MTC, when the temperature at the outlet of gas cooler increases from 35 – 45℃, the COP and ηex are enhanced by 14.1 % - 16.1 % and 12.8 % - 14.2 % compared to BTC, respectively. When gas cooler outlet pressure decreases from 11.0 to 7.5 MPa, the COP and ηex are enhanced by 14.0 % - 22.8 % and 13.4 % - 18.7 %. As the evaporating temperature at the cold side of subcooler increases from -25 to -15℃, the COP and ηex increase from 1.82 to 1.98 and 27.4 % to 29.7 %. With the ratio of refrigeration capacity (Rec) between medium-temperature evaporator and low-temperature evaporator varies from 0.7 to 1.2, the COP and ηex are improved by 10.7 % - 16.3 % and 10.7 % - 15.4 % compared to BTC. There is the maximum exergy loss at gas cooler in the MTC, whereas that of BTC is located in the expansion valve before LT evaporator. The economic analysis shows the cost per unit of exergy of MTC is decreased by 11.5 % under typical operation condition. According to simulation results, the modified cycle has better performance in severe working conditions such as high gas cooler outlet temperature and low gas cooler outlet pressure in the given range of working conditions compared to BTC.

Air Pulsed-Corona discharges for degradation of emerging pharmaceutical pollutants in water and toxicity by-products control

The present study, based a tip-to-plane pulsed corona setup, examined the effects of tip-water distance, radius of curvature of electrode tip, and pulse voltage on the production of liquid-phase RONS used an indicator of degradation performance. Measurements of long-lived RONS species (nitrates, nitrites and H2O2) in deionized water were specifically analyzed. The optimum conditions were used for the removal of a high concentration (500 mg/L) of 4-acetaminophen (i.e. paracetamol) with study of oxidation by-products and their toxicity. The results showed that optimum RONS production in the liquid phase occurred for a short gap distance (4 mm), a tip curvature radius of 100 μm and a pulsed voltage of 10 kV and 10 kHz corresponding to an energetic corona spark regime which is characterized by optical emission spectroscopic measurements. Using these optimal corona discharge parameters, the study showed that after 30 min of exposure to the air plasma, 60 % removal efficiency was achieved at an initial paracetamol concentration of 500 mg/L based on HPLC-DAD sample analysis. GC–MS and LC-MS analysis of treated samples enabled us to identify and characterize two new by-products not previously identified in the literature: N-(4-(4-hydroxyphenylamino) phenyl) acetamide (m/z: 242) and N-(4-aminophenyl) acetamide (m/z: 150), most of which were nitrogen compounds. Further analysis of the toxicity of these by-products to the human cell line (HEK-293) demonstrated that the treated water was not toxic.Overall, these results show that the CDP system is one of the best techniques for treating highly polluted wastewater.

Study on the Influence of Chord Length and Frequency of Hydrofoil Device on the Discharge Characteristics of Floating Matter in Raceway Aquaculture

To investigate the influence of the chord length and frequency of an oscillating hydrofoil device on the discharge characteristics of floating particulate matter, in this study, we take raceway aquaculture as an example and systematically compare and analyze the flow field characteristics of the hydrofoil device with different chord lengths and frequencies, as well as the sewage discharge performance of the raceway based on Computational Fluid Dynamics (CFD). The results indicate that in the particulate matter discharge process of raceway aquaculture, when the chord length and motion frequency of the hydrofoil device are 0.1 W (W is the width of the raceway) and 1.0 Hz, respectively, the anti-Karman vortex streets produced by the hydrofoil device are less affected by the wall, the flow field is the most uniform, the particulate matter discharge performance is the best, and the final floating particulate matter discharge rate reaches up to 99.09%. Adjusting the chord length of the hydrofoil can effectively ameliorate flow field reflux issues, enhancing the uniformity and flow performance of the flow field. When the chord length is 0.1 W, the uniformity of the flow field is optimal. When the chord length is 0.2 W, the flow performance of the flow field is superior. Increasing the frequency enhances the flow performance of the flow field, with an average increase of 0.1 Hz in motion frequency leading to a 19.42% improvement in the average velocity at the outlet. Based on this, we recommend the use of a hydrofoil device with a chord length of 0.1 W and a motion frequency of 1.0 Hz in the raceway aquaculture system to achieve optimal particulate matter discharge performance, providing a theoretical basis and practical guidance for using hydrofoil devices to improve the efficiency of floating particulate matter treatment in raceway aquaculture environments.

Kinetic investigation of discharge performance for Xe, Kr, and Ar in a miniature ion thruster using a fast converging PIC-MCC-DSMC model

Abstract The present work develops a full particle-based model that couples the particle-in-cell plus Monte Carlo collision (PIC-MCC) simulation for plasma dynamics and the direct simulation Monte Carlo (DSMC) method for neutral dynamics in a synergistic iterative manner. This new model overcomes the slow convergence issue in the conventional direct coupling approach caused by the disparity of the time scales between the plasma and neutral dynamics. This model is applied to simulate the behavior of xenon (Xe) and its potential alternatives, krypton (Kr) and argon (Ar), in the discharge chamber of a miniature direct current (DC) ion thruster. The results show that a stable discharge is difficult to achieve for Kr and Ar under the operating conditions optimal for Xe. While increasing the discharge voltage can effectively improve the stability of discharge for Kr and Ar, other common strategies such as changing the magnetic field strength, propellant flow rate, and cathode current are not successful. The propellant utilization efficiency and discharge efficiency are affected by both discharge voltage and propellant flow rate. A maximum utilization efficiency and an optimal discharge efficiency are observed for all three propellants, with the values decreasing in the order of Xe, Kr, and Ar. Moreover, the discharge voltage corresponding to the optimal efficiency is inversely proportional to the square root of the propellant mass, indicating that the ion diffusional loss to the wall, rather than the ionization energy, is the dominant factor affecting the discharge performance for alternative propellants in a miniature DC thruster.

A novel multi-spot structure for joining aluminum and steel dissimilar thin-walled tubes by magnetic pulse crimping

Lightweight manufacture for dissimilar thin-walled tube structures without additional liner support has always been a challenge. A novel magnetic pulse multi-spot joining structure was proposed for the non-weight gain mechanical connection of 6061 aluminum to SPCC (Steel Plate Cold-rolled Common) steel thin-walled tubes. Mechanical properties, microscopic features, and joining mechanism of the magnetic pulse crimping (MPC) joints were explored based on simulation and experiments. Under the geometric conditions of flyer tube with an outer diameter of 30 mm and a thickness of 1 mm, the optimal preformed groove depth and discharge energy for the MPC joints were 2 mm and 16 kJ, respectively. The corresponding maximum tensile and torsional strength were 10.6 kN and 131.2 N m, respectively. The corresponding relative thinning rate of aluminum outer tube was 13 %. The failure forms of the MPC joints were all pull out and torsion out failures. During the high-speed joining of aluminum tube to steel tube, stress concentration phenomena occurred successively at the circumferential bottom fillet, axial bottom fillet, and axial upper edge of the groove. This was due to a certain height difference between the circumferential and axial directions of the groove. It was related to induction distance, discharge energy, skin effect, proximity effect, and tip effect in the coupled field. The yielding and instability of the groove in the steel inner tube would lead to a decrease in the fitting area of the aluminum outer tube filled groove and the relative thinning rate of the aluminum outer tube. This caused a decrease in the mechanical interlocking force at the groove, which was detrimental to the mechanical properties of the MPC joints. This article provides a new approach and data support for the lightweight manufacture of dissimilar thin-walled tube structures.

A day‐ahead energy management strategy for electric vehicles in parking lots considering multi‐scenario simulations and hydrogen storage system

AbstractThis article investigated the charge and discharge management structure of electric vehicles (EVs) in intelligent parking lots (IPLs). It seems that with the expansion of renewable energy sources (RESs) as clean energy and investigation of the effects of EVs on the operation and planning of future distribution networks around the way EVs exchange energy with each other and the upstream network operator, RESs such as solar and wind sources, along with hydrogen storage are essential. Therefore, a new stochastic multi‐scenario approach for charge/discharge management of EVs parked in IPL was proposed, in which a newly developed model for the IPL with a hydrogen storage system (HSS) consisting of a fuel cell, an electrolyzer, and a hydrogen storage tank was presented. In the proposed model, the constraints of upstream network and power balance constraints, with the operating constraints related to the IPL, including EVs, renewable energy sources, and the hydrogen storage system, were formulated as the most important objectives of the optimization problem. The optimization algorithm, Competitive Swarm Optimizer (CSO), was formulated for implementation, and its results were compared with those of the PSO and GWO algorithms. The CSO must handle a variety of practical, large‐scale optimization problems. Based on the obtained results, the excess energy purchased from the upstream network or renewable sources was used as hydrogen storage for consumption during peak hours. As expected, the technical constraints and financial goals of the system were met, and the proposed system was evaluated on a 33‐bus network. As the expected benefits will be the most beneficial with the presence of renewable sources, the final profit will be reduced by taking into account uncertainty for charge/discharge management in EVs such as the uncertainty of electric load, market price, wind turbine, and photovoltaic cell sources. Nonetheless, the profit obtained from renewable resources is preferable to losses resulting from the uncertainty of the system, and according to expectation, the performance of the system for managing the optimal charging and discharging of EVs in the IPL will be acceptable with the maximum profit for the grid.

The nanofiber gel electrolytes with ultra-high ionic conductivity regulated by different acid radical ions for lithium batteries

A nanofiber gel electrolytes with excellent physical properties, electrochemical properties, and cycle life based on poly(vinylidene fluoride)-hexafluoropropylene copolymer modified by magnesium–aluminum bilayered nanosheets (MgAl-LDs) intercalated with different acidic roots ions is prepared by electrostatic spinning. The electrolytes exhibit the best elongation at break of 166 % and tensile strength of 6.59 MPa, and the electrochemical windows are all higher than 5 V. Meanwhile, the ionic conductivity number of nano-GPE intercalated with CO32–, ClO4−, and NO3– reach 5.55*10−3 S/cm, 5.04*10−3 S/cm, and 6.93*10−3 S/cm, respectively. The Li//Li symmetric battery can be stably cycled for more than 1000 h at 1 mA/cm2 with an overpotential of less than 50 mV. The LiFePO4// Li batteries assembled with nano-GPE modified by MgAl-LDs (s = NO3–) show better 0.1-2C multiplicity performance than CO32– and ClO4−, accompanied by an optimal discharge capacity of up to 155 mAhg−1 at 0.1C as well as a high reversible capacity of 135 mAhg−1 and a capacity retention rate of 90 % after 100 cycles at 0.5C. In addition, the results of polarization, X-ray photoelectron spectroscopy (XPS), Computed Tomography (CT), and scanning electron microscope (SEM) tests show that a stable SEI film is formed between nano-GPE and Li anode.

Study on the treatment of oil production wastewater by corona discharge coupling Fenton reagent

As the main by-product of oil production, oil production wastewater has the characteristics of high organic content and poor biodegradability, which makes the low temperature plasma wastewater treatment technology get new development. The Ground electrode atomization negative corona discharge（GEANCD） technology increases the discharge current on the basis of traditional corona discharge, but the uneven atomization of liquid is a key challenge at present, which will have a great impact on the degradation of wastewater pollutants. In this study, the GEANCD reactor was redesigned and a self-developed spiral wire hole electrode (SWHE) was used to replace the conventional wire electrode (WE). The discharge characteristics of the reactor under the two electrode structures were investigated and the optimal discharge parameters were determined. Under the optimum discharge parameters, the treatment effect of the two electrode structures with or without coupling Fenton reagent on oil production wastewater was also compared. The experimental results show that under the optimal discharge parameters of flow rate of 25 mL/min, plate electrode distance of 50 mm and discharge voltage of 14 kV, the reactor equipped with SWHE has higher discharge current, and the treatment effect of oil production wastewater is better when coupled with Fenton reagent.

Ionic liquid coupled plasma promotes acetic acid production during anaerobic fermentation of waste activated sludge: Breaking the restrictions of low bioavailable substrates and altering the metabolic activities of anaerobes

This study explored the potential application of plasma coupling ionic liquid on disintegration of waste activated sludge and enhanced production of short-chain fatty acids (SCFAs) in anaerobic fermentation. Under optimal conditions (dosage of ionic liquid [Emim]OTf = 0.1 g/g VSS (volatile suspended solids) and discharge power of dielectric barrier discharge plasma (DBD) = 75.2 W), the [Emim]OTf/DBD pretreatment increased SCFA production by 302 % and acetic acid ratio by 53 % compared to the control. Mechanistic investigations revealed that the [Emim]OTf/DBD combination motivated the generation of various reactive species (such as H2O2, O3, •OH, 1O2, ONOO−, and •O2−) and enhanced the utilization of physical energies (such as heat). The coupling effects of [Emim]OTf/DBD synergistically improved the disintegration of sludge and biodegradability of dissolved organic matter, promoting the sludge anaerobic fermentation process. Moreover, the [Emim]OTf/DBD pretreatment enriched hydrolysis and SCFAs-forming bacteria while inhibiting SCFAs-consuming bacteria. The net effect was pronounced expression of genes encoding key enzymes (such as alpha-glucosidase, endoglucanase, beta-glucosidase, l-lactate/D-lactate dehydrogenase, and butyrate kinase) involved in the SCFA-producing pathway, enhancing the production of SCFAs from sludge anaerobic fermentation. In addition, [Emim]OTf/DBD pretreatment facilitated sludge dewatering and heavy metal removal. Therefore, [Emim]OTf/DBD pretreatment is a promising approach to advancing sludge reduction, recyclability, and valuable resource recovery.

Multi-factor coupling optimization of heat recovery effectiveness in a transcritical CO2 heat pump

In the background of energy shortage and climate change, transcritical CO2 heat pump(HTP) technology has attracted lots of attention because of its energy-saving and environmentally friendly advantages. In this research, an experimentally verified simulation model of transcritical CO2 HTP is established to investigate multi-factor coupling optimization of heat recovery effectiveness(ηIHX). First, the coupling optimization mechanism of ηIHX and discharge pressure(pdis) is analyzed. Moreover, this research explores the influence of ηIHX on heating capacity, power consumption, discharge temperature(tdis), and internal heat exchanger(IHX) cost, and further proposes a comprehensive heat recovery index to optimize the above factors. Based on this index the optimal heat recovery effectiveness(ηIHX,opt) for each operating condition is obtained. Also, a failure boundary for the coupling optimization of the ηIHX is also indicated. In addition, the optimal discharge pressure(pdis,opt) prediction correlation for different ηIHXs is proposed, which can be used for heat recovery effectiveness collaborative optimization control. Finally, a general method for evaluating IHX is provided. Taking Xi'an as an example, the optimal heat recovery area(AIHX,opt) of this HTP system is 0.42m2, with which the optimized HTP system operates safely at extreme operating conditions, resulting in an annual lucre of 1,211 CNY.

·OH Scavenger Optimized Grounding Electrode Atomization Corona Discharge Technology for Treatment of Coal Mine Acidic Wastewater

Coal mine acid drainage is a type of industrial wastewater generated in the process of coal production and utilization that has a low pH and contains a small amount of organic matter and SO42−, which is harmful to the environment. The ·OH scavenger was used to optimize the grounded electrode atomized corona discharge (GEACD) technology for the treatment of coal mine acidic wastewater. The effects of various factors on the discharge effect were investigated, and the optimal operating scheme for the subsequent test was determined as 35 mm distance between barrel electrodes, 0.6 mm diameter of wire electrodes, and a flow rate of 45 mL/min. The effects of discharge voltage, discharge time, and ·OH scavenger on COD removal rate and pH in coal mine acid drainage were also investigated. The results showed that at the optimum discharge voltage of 12 kV, discharge time of 66 min, and SO42− to ethanol concentration ratio of 1, the COD value decreased from 152.84 mg/L to 43.27 mg/L, and the pH value increased from 5.6 to 6.1.

Consistency of Physical Therapist Discharge Recommendations in Acute Care

Introduction: Physical therapists assist with discharge planning for hospitalized patients by making recommendations regarding a patient’s optimal discharge location and ongoing rehabilitation needs. The purpose of this study was to examine the consistency of discharge recommendations made by physical therapists with experience working in an acute care setting, when provided with a set of clinical vignettes describing hospitalized patients. Review of Literature: Considering the complex/multifactorial nature of making discharge recommendations, one would expect there to be inconsistencies among physical therapists. However, we are not aware of a previous study examining the level of consistency for discharge recommendations made by physical therapists, when reviewing a set of clinical vignettes. Subjects: Nineteen physical therapists working in an acute care setting. Methods: The physical therapists were provided with 10 clinical vignettes describing hospitalized patients via an electronic survey distributed across three rehabilitation departments. Each vignette described the patient’s medical condition, past medical history, prior level of function, living situation, key examination findings, and other general characteristics. After independently reviewing each case, the physical therapists selected a discharge recommendation from a list of standard options. Fleiss’ kappa was examined to assess the level of agreement among the physical therapists. Results: Overall, Fleiss’ kappa was 0.28, which reflects fair agreement among the physical therapists. Discussion and Conclusion: The 19 physical therapists who participated in this study only exhibited fair agreement with respect to their discharge recommendations. This relatively low level of agreement suggests that efforts to improve the consistency of discharge recommendations should be explored.

Nanosecond-pulsed plasma protects against bacterial fruit blotch and promotes melon seedling growth.

Bacterial fruit blotch (BFB), known as the 'cancer' of cucurbits, is a seed-borne disease of melons caused by Acidovorax citrulli. Traditional chemical treatments for BFB are ineffective and adversely affect the environment. Using dielectric barrier discharge (DBD) nanosecond-pulsed plasma technology, melon seeds were treated to promote germination and growth and to control BFB. Based on the evaluation parameters of seed germination, seedling growth, leaf yellowing and bacterial infection after seed plasma treatments, 9 min at 20 kV was selected as the optimal plasma discharge parameter. In this study, seedling growth was significantly improved after treating melon seeds carrying A. citrulli using this discharge parameter. The number of first true leaves measured on the eighth day was 2.3 times higher and the disease index was reduced by 60.5% compared to the control group. Attenuated total reflectance-Fourier transform infrared measurements show that plasma treatments penetrate the seed coat and denature polysaccharides and proteins in the seed kernel, affecting their growth and sterilization properties. Pre-sowing treatment of melon seeds carrying A. citrulli using nanosecond-pulsed plasma technology can effectively control seedling BFB disease and promote melon seedling growth by optimizing DBD parameters. © 2024 Society of Chemical Industry.

Cost optimization of electricity in energy storage system by dynamic programming

This paper presents a dynamic programming solution for the cost optimization of an electric storage system. The objective is to minimize the total cost of meeting electricity demand over a specified time interval, considering energy constraints and costs. The proposed algorithm efficiently determines the optimal energy discharge and charge strategies for the storage system, resulting in reduced overall costs. The effectiveness and efficiency of the algorithm are demonstrated through various test cases, highlighting its potential for real-world applications in energy storage systems and electric grid management. It also provides an overview of different types of electrical storage systems, review recent research on optimization techniques for energy storage, and examines recent studies on the optimization of electrical storage systems for specific applications, such as peak load shaving and grid stability. Through this comprehensive analysis, we hope to shed light on the current state of the field and identify areas for further research and improvement.

Ecohydrological indicators and environmental flow assessment in the middle and lower reaches of the Huai River, China

The vitality of river ecosystems is vital for the sustainable development of river basins, with the assessment of environmental flow (EF) playing a pivotal role in eco-informatics. This study delves into the middle and lower reaches (MLR) of the Huai River basin (HRB) in China, utilizing hydrological data spanning from 1950 to 2020. Its principal objective lies in the selection of ecohydrological indicators to refine the estimation of EF in the HRB. Employing principal component analysis (PCA), ecologically relevant hydrological indicators (ERHIs) were discerned and scrutinized for their hydrological characteristics. The analysis extended to evaluating hydrological shifts at different stations using ERHIs, determining suitable EF in the MLR, and delineating the trajectories of appropriate intra-annual flows in different hydrological years through HEC-RPT. Based on a variety of mutation test methods, the change point of runoff sequence was determined in 1991. The PCA analysis identified eight ERHIs, reflecting hydrological changes of 49.79 % and 56.26 % at Bengbu and Sanhezha, respectively, which indicate a moderate alteration. Based on ERHIs, the other stations in the HRB exhibited hydrological alterations ranging from 33 % to 47 %, notably highlighting substantial changes in maximal 30d flow and flow fall rate. The optimal flood pulse discharge in the middle reaches is 4150 m3/s, 3140 m3/s and 2150 m3/s in wet, dry and dry years, respectively. Downstream, flood pulse flow in wet, normal and dry years should exceed 4070 m3/s, 3110 m3/s and 1980 m3/s, respectively. The research contributes significantly to the management of rivers and the sustainable conservation of the ecological milieu.

Unveiling a 72.5 GPa peak hardness in sustainable nanodiamond composite hard coatings via discharge energy control: A nanoindentation-Raman approach

Sustainable nanodiamond composite (NDC) films hold promise for high-performance hard coatings thanks to coaxial arc plasma deposition (CAPD). This eco-friendly technique eliminates the need for external heating, chemical reactions, or Co substrate pre-treatment. CAPD boasts lower energy consumption and faster deposition rates, making it a sustainable solution for the growing demand for high-quality, environmentally friendly coatings. This study investigates the influence of discharge energy on the nanostructure and mechanical properties of these NDC films. Optimal discharge energy, ranging from 2.3 to 12 J/pulse, was meticulously explored. A combined nanoindentation-Raman approach reveals a significant correlation between discharge energy and film properties. Remarkably, at 7 J/pulse, a peak hardness of 72.5 GPa is achieved, surpassing other energy levels. Raman spectroscopy confirms maximum nanodiamond content at this energy level (evidenced by maximized Adia/AG ratio, indicating a higher diamond-to-graphite ratio), along with minimal graphitization. Additionally, the presence of trans-polyacetylene (t-PA) peaks (denoted as At-PA) revealed the existence of maximum grain boundaries ratio (At-PA/AG), contributing to enhanced mechanical properties. Optimizing discharge energy tailors NDC film nanostructure, enhancing mechanical performance for advanced hard coatings.