Charge Level Research Articles

Electrochemical Impedance Spectrum (EIS) Variation of Lithium-Ion Batteries Due to Resting Times in the Charging Processes

The electrochemical impedance spectrum (EIS) is a non-destructive technique for the on-line evaluation and monitoring of the performance of lithium-ion batteries. However, the measured EIS can be unstable and inaccurate without the proper resting time. Therefore, we conducted comprehensive EIS tests during the charging process and at different state of charge (SOC) levels with various resting times. The test results revealed two findings: (1) EIS tests with a constant long resting time showed a clear pattern in the impedance spectral radius—a decrease followed by a slight increase. We analyzed the impedance data using an equivalent circuit model and explained the changes through circuit parameters. (2) We examined the effect of resting time on impedance at consistent SOC levels. While low SOC levels exhibited significant sensitivity to resting time, medium SOC levels showed less sensitivity, and high SOC levels had minimal impact on resting time. The equivalent circuit parameters matched the observed trends. Kramers–Kronig transformation was conducted to assess the reliability of the experiments. This study not only summarizes the relationship between the EIS and SOC but also highlights the importance of resting time in impedance analysis. Recognizing the role of the resting time could enhance impedance-based battery studies, contribute to refined battery status evaluation, and help researchers to design proper test protocols.

The Practical Application of Bio-Inspired PMA for the Detection of Partial Discharges in High Voltage Equipment

In this paper, the practical application of a bio-inspired antenna for partial discharge (PD) detection in high voltage equipment was evaluated in order to validate the efficiency of using this technology for PD monitoring purposes. For this, PD measurements using the bio-inspired antenna were performed on operational 69 kV potential transformers (PT) in a real substation. After the field experiment, laboratory measurements using the IEC 60270 standard method and a bio-inspired antenna were performed, simultaneously, over the evaluated PT. The results obtained at the substation indicated suspicious frequencies of partial discharge activity in two out of three evaluated potential transformers, mainly for the frequencies of 461 MHz, 1366 MHz, 1550 MHz and 1960 MHz. During the laboratory tests, the presence of partial discharge activity over the suspicious potential transformers was confirmed with the detection of PD apparent charge levels above 20 pC. Finally, the frequency spectrum obtained from the PD signals detected by the bio-inspired antenna in the laboratory presented similar frequency values to those obtained during the practical application at the substation, making it a promising indicator for future defect classification studies using artificial intelligence.

Exogenous brassinolide treatment regulates phenolic accumulation in mung bean sprouts through the modulation of sugar and energy metabolism.

The effects of exogenous brassinolide (BR) treatment (3.0 μmol L-1 ) on phenolic biosynthesis in mung bean sprouts were investigated. This investigation included the analysis of sugar content, substrates within the phenylpropane pathway, energy substances, enzymatic activity within the phenylpropane pathway, sugar metabolism and energy metabolism. Results showed that BR treatment significantly increased the levels of total phenolics, p-hydroxybenzoic acid, p-coumaric acid, gallic acid, fumalic acid and caffeic acid. This enhancement was accomplished through the elevation of l-phenylalanine levels and the activation of enzymes associated with the phenylpropane pathway in mung bean sprouts, including phenylalanine ammonia-lyase, cinnamate 4-hydroxylase and 4-coumarate CoA ligase. Furthermore, BR treatment induced alterations in sugar metabolism in mung bean sprouts as evidenced by the increased levels of glucose, fructose, sucrose and phosphoenolpyruvate. Moreover, increased activity was observed for enzymes linked to sucrose metabolism and glycolysis in the BR-treated group. Concurrently, BR treatment bolstered the levels of adenosine triphosphate and energy charge in mung bean sprouts, which was attributed to the activation of H+ -adenosine triphosphatase, Ca2+ -adenosine triphosphatase and succinic dehydrogenase. These results suggest that BR treatment can accelerate the accumulation of phenolic compounds in mung bean sprouts. This effect is achieved not only through the activation of the phenylpropane pathway, but also through the modulation of sugar and energy metabolism. The modulation provides ample energy and a substrate for the biosynthesis of phenolics. © 2023 Society of Chemical Industry.

Effect of surface acetylation of chitin nanocrystals on the preparation and viscoelasticity of sunflower seed oil-in-water Pickering emulsions

Acetylated chitin nanocrystals (ChNCs) were used as stabilizer in this work to prepare sunflower seed oil-in-water emulsions for the morphological and rheological studies. The results revealed that the acetylation with moderate degree of substitution (0.38) reduced hydrophilicity and increased surface charge level of rod-like ChNCs, and as a result, significantly improved the emulsifying ability of ChNCs. At the same oil/water ratio and particle loading, the emulsions stabilized with the acetylated ChNCs had far smaller droplet size (∼3 μm) as compared to the emulsions stabilized with the pristine ChNCs (5–7 μm). The increased droplets numbers and improved surface coating level resulted in the enhanced viscous resistance and yield stress level, which improved the physical stability of the acetylated ChNC-stabilized emulsions as a result. In addition, the droplet clusters easily formed in this system, contributing to weak strain overshoot and decreased large-deformation sensitivity during dynamic shear flow. Therefore, the acetylated ChNC-stabilized system showed enhanced transient stress overshoot during startup flow and weakened thixotropy during cyclic ramp shear flow as compared to the pristine ChNC-stabilized system. The relationships between surface acetylation of ChNCs and flow behavior of emulsions were then established, which provide valuable information on the modulation of the ChNC-stabilized Pickering emulsions.

Unraveling the Characteristics of ESS Fires in South Korea: An In-Depth Analysis of ESS Fire Investigation Outcomes

Unlike traditional coal-powered energy generation, renewable energy sources do not generate carbon dioxide emissions. To enhance the efficiency of renewable energy systems, energy storage systems (ESSs) have been implemented. However, in South Korea, ESS fire incidents have emerged as a significant social problem. Consequently, a government-formed committee was established to investigate the cause of these fires through the analysis of the data collected from ESSs, stored in the battery management system (BMS) log data of the fire-resistant safe storage. In the first phase of the investigation, the committee was unable to identify the underlying characteristic of ESS fires. Nevertheless, in the second phase, the investigation committee could identify the key characteristics of ESS fires by analyzing the BMS log data. ESS fires were found to occur when the state of charge level was more than 95% and during the initiation of thermal runaway in specific cells. Despite these findings, the committee was unable to determine the root cause of ESS fires.

Axisymmetric inertialess model for the capture of airborne microparticles using an electrospray

We theoretically analyze the effectiveness of an electrospray of ultrafine droplets to filter out micron sized particles from a gas stream. To that end, we introduce an axisymmetric configuration where the airborne particles merge with the electrospray. The droplets attach to the particles, charging them, and both droplets and charged particles are eventually driven towards a collector by means of an electric field. The attachment process is described through a set of reaction constants based on calculated collision cross-sections, yielding particles with different charge levels. The problem involves computation of the concentrations of each type of particle, the gas flow, and the electric field due to the applied voltages and the space charge. Preliminary numerical simulations show a filtration efficiency that is above 95% for particles larger than about 2μm and rapidly declines for smaller particles, though this drop of the efficiency can be postponed to smaller particle sizes by decreasing the ratio of particle to electrospray fluxes or the ratio of the inlet velocity of the particle carrying gas to the velocity induced by electric forces inside the device. Pending an exhaustive numerical exploration of the parameter space of the system, these results also show that the gas flow structure, which is strongly affected by the charged particles, is key for high filtration efficiency.

Single Elementary Charge Fluctuations on Nanoparticles in Aqueous Solution.

100 years ago, in 1923, the Nobel prize in physics was awarded for measurement of the unit charge. In addition to a profound impact on contemporary physics, this discovery has reshaped our understanding of charge-based interactions in chemistry and biology, ranging from oxidation and ionization to protein folding and metabolism. In a liquid, the discrete nature of the electric charge becomes prominent at the nanoscale when a charge carrier is exchanged between a molecule or a nanoparticle and the surrounding medium. However, our ability to observe the dynamics of such interactions at the level of a single elementary charge is limited due to the abundance of ions in water. Here, we report on the observation of single binding-unbinding events with elementary charge resolution at the surface of a nanoparticle suspended in water. Discrete steps in the electrical charge are revealed by analyzing the motion of optically trapped nanoparticles under the influence of an applied sinusoidal electric field. The measurements are sufficiently fast and long to observe individual (dis)charging events that occur on average every 3 s. Our results offer prospective routes for studying the dynamics of diverse chemical and biological phenomena on the nanoscale with elementary charge resolution.

Modal analysis of lithium-ion batteries for estimation of state of charge and state of health

The robustness and safety of battery-operated systems will become critically important as society transitions away from fossil fuels. In the foreseeable future, lithium-ion batteries will be used for high-power, high-capacity applications such as electric vehicles and renewable energy storage. In these applications, which require thousands of cells, existing battery management systems do not monitor the operating conditions of each cell. Variability in temperature and pressure can affect a cell’s state of charge (SOC) or state of health (SOH). This environmental loading coupled with cell-to-cell variability makes SOC/SOH estimation very difficult. Inaccurate measurements of SOC/SOH can reduce the lifespan of battery systems or lead to accidental overcharge and thermal runaway. We present modal analysis as a viable approach to estimate SOC/SOH for electrically cycled cells. Modal tests are performed using laser Doppler vibrometry on 10 Ah Nickel–Manganese–Cobalt pouch cells at 0% and 100% SOC across more than 30 cycles. Changes in the resonance frequencies of the cell are correlated with SOC/SOH to provide an understanding of how the mechanical properties of cell components change as a function of charge level and aging. This work demonstrates that modal analysis may be used as a tool for regular battery maintenance to improve battery safety.

Operation Parameters Variation of Air Source Heat Pump According to the Outdoor Temperature

Air source heat pumps (ASHP), known as energy efficient systems, emerge as environmentally friendly and economical solutions for building heating. Unfortunately, the operating parameters of ASHPs and accordingly their performance are directly affected by the daily and seasonal temperature changes of the outside air. In this study, change in operation parameters of a selected ASHP with 3.4kW nominal heating capacity is investigated with a calculation method based on the logarithmic mean temperature difference, between -10°C to 18°C outdoor temperature range with 2°C steps, at constant compressor power. The study is verified with published COP data of the manufacturer. Results are shared with graphs that give the variation of refrigerant evaporation and condensation temperature and pressure, COP, and condenser heating load according to outdoor air temperature. A raise from -10°C to 18°C in outdoor temperature, increases the COP value from 3.38 to 5.49. Detection of the increase in evaporation pressure in parallel with the outdoor temperature may allow easy control of the refrigerant charge level with a manometer. This study can be a useful guide for researchers who aim to determine the outdoor temperature dependent operating parameters of an ASHP and for technical personnel who need this information in fields.

전자담배의 과세형평성에 관한 연구

As liquid e-cigarettes were distributed and sold in Korea, the definition and taxation basis for e-cigarettes were newly established in regulations related to tax levies such as the Local Tax Act related to tobacco taxation, and the law was revised again to impose tax levies at 89% of general cigarettes as cigarette-type e-cigarettes emerged. However, since e-cigarettes are taxed at a lower level than general cigarettes without a clear basis, it is necessary to discuss this. As can be seen in the previous study (Darshak Sanghavi, 2014), in fact, in order to reduce the smoking rate, it may be more effective to prevent the first smoking of adolescents rather than inducing smokers to quit smoking. Therefore, relatively less tax charges should not be imposed on e-cigarettes, giving the effect of encouraging smoking of e-cigarettes.
 In terms of taxation equity with general cigarettes and smoking cessation policies, it is necessary to revise part of the Local Tax Act so that e-cigarettes can be taxed at the same level as general cigarettes, and through the revision of the Individual Consumption Tax Act and the National Health Promotion Act, the level of tax charges for general cigarettes and e-cigarettes must be the same. Currently, e-cigarettes are taxed lower to encourage smoking of e-cigarettes.This study attempted to summarize the problem of taxation equity of e-cigarettes, which has been discussed continuously, and to suggest a solution to this. It is hoped that the results of this study will further rationalize the taxation system of tobacco-related tax charges in Korea and contribute a little to the establishment of taxation policies that both smokers and non-smokers can agree on.

Optimal Fractional-Order Controller for the Voltage Stability of a DC Microgrid Feeding an Electric Vehicle Charging Station

Charging stations are regarded as the cornerstone of electric vehicle (EV) development and utilization. Electric vehicle charging stations (EVCSs) are now energized via standalone microgrids that utilize renewable energy sources and reduce the stress on the utility grid. However, the control and energy management of EVCSs are challenging tasks because they are nonlinear and time-varying. This study suggests a fractional-order proportional integral (FOPI) controller to improve the performance and energy management of a standalone EVCS microgrid. The microgrid is supplied mainly by photovoltaic (PV) energy and utilizes a battery as an energy storage system (ESS). The FOPI’s settings are best created utilizing the grey wolf optimization (GWO) method to attain the highest performance possible. The grey wolf is run for 100 iterations using 20 wolves. In addition, after 80 iterations for the specified goal function, the GWO algorithm almost discovers the ideal values. For changes in solar insolation, the performance of the proposed FOPI controller is compared with that of a traditional PI controller. The Matlab/Simulink platform models and simulates the EVCS’s microgrid. The results demonstrate that the suggested FOPI controller significantly improves the transient responsiveness of the EVCS performance compared to the standard PI controller. Despite all PV insolation disruptions, the EV battery continues to charge while the ESS battery precisely stores and balances PV energy changes. The results support the suggested FOPI control’s robustness to parameter mismatches. The microgrid’s efficiency fluctuations with the insolation level and state of charge of the EV battery are discussed.

Photocatalytic titanium dioxide reduces postharvest decay of nectarine fruit packaged in different materials through modulating central carbon and energy metabolisms

The capacity of titanium dioxide (TiO2) photocatalysis photocatalytic reactor to prevent and control pathogen infection in nectarine fruit packed in laminated nylon/LDPE, low density polyethylene and microperforated LDPE films was evaluated. Results showed that TiO2 combined with microperforated LDPE packaging (TPL) exhibited superior inhibition of microbial growth, reducing total viable counts by 4.18 log CFU g−1 and yeast and mold counts by 3.20 log CFU g−1, compared to microperforated LDPE packaging alone. TiO2 photocatalysis primed the defense systems in nectarine fruit packed in microperforated LDPE, improving the activity of defense-related enzymes. Metabolomics analysis indicated that l-aspartate, oxaloacetate, and succinic acid involved in central carbon metabolism including the glycolysis and tricarboxylic acid cycle pathways, were significantly upregulated by TPL. TiO2 increased the activity of energy metabolism-related enzymes, adenosine triphosphate, adenosine diphosphate, and energy charge levels to provide adequate energy, thus reducing fruit decay.

Development of high-performance MXene/nickel cobalt phosphate nanocomposite for electrochromic energy storage system using response surface methodology

Integrating electrochromism and energy storage capabilities of materials into a supercapacitor has great potential for developing intelligent and sustainable power systems and electronics. An intriguing aspect of such materials is their ability to undergo a real-time color change, indicative of the supercapacitor's charge level. In this work, Ti3C2 MXene/nickel cobalt phosphate (MXene/NiCoP) nanocomposite was successfully prepared by electrodeposition followed by spin-coating. The MXene/NiCoP nanocomposite was optimized using response surface methodology/central composite design (RSM/CCD). The proposed quadratic model displayed a residual standard error (RSE) of <5 %, indicating good model predictability. The conformational investigations, which included FTIR, Raman, XRD, XPS, FESEM, mapping, and EDX show that MXene/NiCoP nanocomposite was successfully synthesized. The synergistic effect offered by MXene/NiCoP nanocomposite resulted in superior and remarkable electrochromic energy storage performances in terms of coloration efficiency (56 cm2/C), optical contrast retention (84.45 %), specific capacity (453 mAh/g) and cycling stability (94.12 % after 5000 cycles). The MXene/NiCoP nanocomposite has exhibited exceptional electrochromic and supercapacitive properties, making it a promising candidate for advanced electroactive materials in future intelligent hybrid energy storage systems.

Riboflavin application regulates sugar and energy metabolism in strawberries during cold storage

The commercial and nutritional value of strawberry fruit is drastically reduced due to its susceptibility to decay fungal diseases. In this study, we employed 40 μM riboflavin to delay senescence and decay of strawberry fruit during storage at 4 °C for 12 d. The findings showed that the treatment decreased strawberries mass loss, respiration rate, ROS level, and MDA content and maintained soluble sugars level. Riboflavin treatment maintained high levels of ATP content and energy charge, and activated the activities of succinate dehydrogenase (SDH), cytochrome C oxidase (CCO), H+-ATPase, Ca+-ATPase, glucokinase (GK), fructokinase (FRK), glucose-6-phosphate dehydrogenase (G6PDH), and 6-phosphogluconate dehydrogenase (6-P-GDH) and up-regulated the expression of their encoding genes. In addition, riboflavin-mediated NAD kinase (NADK) activation accelerated the conversion of NAD+ to DADP+ and the accumulation of DADPH. The respiratory pathway switched from the glycolytic (EMP)-tricarboxylic acid cycle (TCA) to the pentose phosphate pathway (PPP), reducing respiratory consumption. As a result, our findings suggest that riboflavin supplementation after harvest maintains a higher level of energy and delays senescence in strawberries.

CDAR-DRAM: Enabling Runtime DRAM Performance and Energy Optimization via In-Situ Charge Detection and Adaptive Data Restoration

With the increasing of DRAM’s capacity, the refresh operation rapidly becomes a major concern to the performance of the current computational system. Moreover, conservative timing parameters adopted for access operations make an increasing amount of negative impact on system performance and energy efficiency. In this paper, we propose an in-situ charge detection and adaptive data restoration DRAM (CDAR-DRAM) architecture, which can dynamically adjust the refresh rate and relax the constraints on access timing by removing pessimistic timing margins for PVT variations. CDAR-DRAM employs a lowcost skewed-inverter-based detector to monitor the bitline voltage in runtime and estimate real-time timing parameters of cells. Based on the detector, an adaptive refresh and restore scheme (CDAR-ref) is presented, which progressively reduces the refresh rate and partially restores cells’ voltage just enough for cells with sufficient charge, thereby optimizing both refresh and restoration operations. Moreover, a supplementary adaptive access scheme (CDAR-acc) is presented, which detects the runtime charge level of recently-accessed rows and reduces access latency aggressively, benefitting workloads in a single-core system and memory nonintensive workloads in a multi-core system. CDAR’s flexibility allows the two schemes to be combined. The evaluation shows that in an 8-core system, the combined scheme improves performance and energy efficiency by 15.2% and 22.6%, respectively.

Static Cling: A Mechanical Side-Effect of Dielectric Charging

Space charging of dielectrics results in the build-up of electric fields between the trapped charge (typically electrons) and image charges in nearby conductors. Engineering assessments are typically concerned with the magnitude of the electric field relative to a discharge threshold. The same electric field, however, also results in strong electrostatic attraction. For rigid dielectrics (such as solar cell coverglasses, second surface mirrors, or printed circuit boards), the electrostatic forces have no consequences. But for lightweight flexible dielectrics, the electrostatic forces can lead to static cling. A simple 1-D analysis of the electrostatic force between trapped and image charges is presented, and the phenomenon is demonstrated by ground test video. The electrostatic force is sufficient to overcome the Earth’s gravitational force. The video shows significant movement in a single-layer thermal blanket of a periodic nature. As the material reaches a sufficient charge level, the electrostatic forces begin to dominate and the material starts moving until it makes contact with the ground plane, discharges, and the cycle begins again. Without the vacuum-deposited aluminum (VDA) layer on the Kapton film, the static cling would be permanent.

Environmental impact assessment of an air-to-water heat pump through the expanded total equivalent warming impact index based on experimental data

The Total Equivalent Warming Impact (TEWI) index is conventionally used to evaluate emissions from heating, ventilation, air conditioning and refrigeration (HVAC&R) systems. However, a more comprehensive indicator, the Expanded Total Equivalent Warming Impact (ETEWI), has been proposed to overcome the limits of TEWI index and to consider additional environmental impacts such as the effects of urban heat island and the natural gas losses along high-pressure pipelines supplying gaseous fuel to natural gas-fired power plants. In this study, TEWI and ETEWI metrics are applied to an air-to-water electric heat pump (EHP) serving a university building in Benevento (Southern Italy). Real data on EHP electricity consumption have been derived from the entire building's electric load and compared to measured data. ETEWI index has been estimated in two scenarios, one considering the impact of refrigerant charge variation on the performance of the EHP and its environmental impact and the other disregarding it. Additionally, carbon dioxide emission factors for electricity production have been forecasted from 2021 to 2033 to determine the indirect term of ETEWI index. Over the lifetime of the EHP, ETEWI increases by 4.8% compared to TEWI when the variation of refrigerant charge level is not considered. However, this percentage growth is equal to 6.5% when the impact of refrigerant charge change is accounted too. In the latter scenario, the indirect term of ETEWI decreases from 22.7 tCO2 in 2015 to 12.0 tCO2 in 2033 when the forecast of the carbon dioxide emission factors for electricity production is taken into account.

Inhibitory Activity and Mechanism of Action with Thymol against the Blueberry Pathogenic Fungi Caused by Neopestalotiopsis clavispora

Decay caused by Neopestalotiopsis clavispora is an important postharvest disease of blueberries that seriously affects the commercial value of blueberry fruit. In this paper, we studied the inhibitory activity and mode of action of thymol against the pathogenic fungus of blueberries caused by Neopestalotiopsis clavispora. The results demonstrated that thymol administration could limit mycelial growth in vitro; the inhibitory effect was positively connected with thymol mass concentrations, and the minimal inhibitory concentration (MIC) was 100 mg/L. Further investigations revealed that MIC thymol treatment dramatically reduced the germination of pathogenic spores and led to an increase in the conductivity of the pathogen, leakage of contents, and a decrease in pH. Propidium iodide (PI) staining experiments demonstrated that MIC thymol caused damage to mycelial cell membranes. Additionally, MIC thymol treatment promoted mycelium malondialdehyde content accumulation, inhibited superoxide dismutase (SOD) and catalase (CAT) enzyme activities, decreased adenosine triphosphate (ATP), adenosine diphosphate (ADP), and adenosine monophosphate (AMP) content and energy charge levels, and the fluorescence intensity of mycelium caused by MIC thymol treatment was significantly increased by the 2,7-Dichlorodi-hydrofluorescein diacetate (DCFH-DA) assay. The results of this study indicate that thymol suppresses the proliferation of Neopestalotiopsis clavispora by compromising the integrity of their cell membranes, promoting the accumulation of cellular reactive oxygen species (ROS), and interfering with energy metabolism.

Development and demonstration of a method to detect refrigerant charge level for variable refrigerant volume systems

Unlike traditional direct expansion systems, variable refrigerant flow (VRF) systems have longer routing, more complicated setup, and sophisticated controls and require much more refrigerant for proper operation. Proper refrigerant charge becomes more critical to their operations. Intensive studies have investigated refrigerant charge faults for VRF systems. Due to the daunting complexity, few studies use knowledge-based fault detection and diagnosis (FDD) methods. Most of them use data-driven FDD methods to study this fault. Although they seem promising, these methods can only handle single faults and are not scalable or interpretable. This paper proposes a decoupling-based FDD method to detect and diagnose improper refrigerant charge in VRF systems. This method was originally proposed by our previous work for rooftop units (RTUs) and split systems, which has been tested and validated by extensive studies. Due to the differences between VRF and RTU, the original method – virtual refrigerant charge sensor (VRC) for VRF is modified, analyzed, and investigated in detail. Data filter criteria were implemented to eliminate noisy data. The modified VRC, when combined with a data filter, was tested on two systems in the field. The results demonstrated its effectiveness in detecting an undercharged system, specifically a 30 % undercharge.

Power Smoothing Strategy for Wind Generation Based on Fuzzy Control Strategy with Battery Energy Storage System

This work discusses the use of a battery energy storage system applied to the smoothing of power generated at the output of wind turbines based on a fuzzy logic power control. The fuzzy control logic proposed can perform the aforementioned activity while the state of charge of the energy storage system is maintained within operational limits. In order to assess the fuzzy logic power control’s effectiveness at maintaining the state of charge levels within the allowed range, two operating situations are explored: one in which the state of charge is above the upper limit allowed, and another in which the state of charge is in the minimum value allowed. The numerical results show that, when using the battery energy storage system in conjunction with the control logic proposed, the active power provided as the point of common coupling by the wind turbines can be smoothed, thus contributing to the Electric Power System reliability and stability. The main results of this paper are based on measurements of wind and active power associated with a wind generation plant installed in the northeast region of Brazil and equipped with 2.1 MW wind turbines.