Reverse Charging Research Articles

Experimental study on energy storage characteristics of packed bed using different solid materials

The packed bed energy storage system can solve the mismatch between solar energy supply and demand at a low cost. The physical properties of storage materials have a decisive impact on the performance of storage systems. Different scenarios may require different storage materials. Studying the impact of storage materials on storage characteristics is crucial. However, the comparative analysis and research on different TES materials are focused on characterization and numerical simulation but less on packed bed TES experiments. This paper evaluates the thermal durabilities of three materials, including sintered ore particles, alumina balls, and rock particles, through thermal cycling tests. Through packed bed heat storage experiments, the energy storage characteristics and thermocline evolution characteristics of three beds under different operating conditions are compared and analyzed. The results indicate that all materials exhibit excellent thermal durabilities. A larger bed voidage and smaller bed heat capacity are beneficial for thermal diffusion in the bed. When reverse charging, the natural convection of air in the bed enhances the convective heat transfer effect, resulting in a higher charging power. The existence of natural convection promotes the mixing of cold air and hot air in the tank, increases the irreversibility of the process, and leads to a significantly lower efficiency in reverse flow compared to that in forward flow. When changing the airflow direction, the system overall exergy efficiencies of SOP, alumina, and rock bed decrease from 74.1 %, 72.4 %, and 77.2 % to 47.0 %, 39.9 %, and 45.8 %, respectively. Regardless of the airflow direction, the smaller the bed voidage and the larger the bed heat capacity, the better the maintenance characteristics of the thermocline.

Analysis of Energy Transmission and Design of Additional Capacitance for a Novel Secondary Side Parallel LCD Forward Converter

For the deficiency of low utilization ratio of transformer excitation energy, complex circuit structure, low efficiency and low output power in the existing magnetic reset technology, a secondary parallel LCD forward converter which can avoid reverse charging of additional capacitor is proposed. According to the different working modes of inductors in the proposed converter, the converter is divided into different combined working modes, and the working principles of different combined working modes are analyzed in detail. At the same time, the influence of additional LCD circuit on the performance of the proposed converter is deeply studied based on the working principles of different combination modes. According to the performance analysis, the analytical expression of additional capacitance on the working mode is derived, and the optimal design scheme of additional capacitance parameters is put forward. Finally, in order to verify the effect of the additional capacitance C2 on the operation mode of the converter, an experimental analysis of the secondary parallel LCD forward converter which can avoid the reverse charging of the additional capacitor is carried out. The experimental waveform analysis verifies the correctness of the theoretical analysis and the feasibility of the design method of the additional capacitor parameters.

Redox Catalysis Promoted Activation of Sulfur Redox Chemistry for Energy-Dense Flexible Solid-State Zn-S Battery.

In aqueous Zn-ion batteries, the intercalation chemistry often foil attempts at the realization of high energy density. Unlocking the full potential of zinc-sulfur redox chemistry requires the manipulation of the feedbacks between kinetic response and the cathode's composition. The cell degradation mechanism also should be tracked simultaneously. Herein, we design a high-energy Zn-S system where the high-capacity cathode was fabricated by in situ interfacial polymerization of Fe(CN)64--doped polyaniline within the sulfur nanoparticle. Compared with sulfur, the FeII/III(CN)64/3- redox mediators exhibit substantially faster cation (de)insertion kinetics. The higher cathodic potential (FeII(CN)64-/FeIII(CN)63- ∼ 0.8 V vs S/S2- ∼ 0.4 V) spontaneously catalyzes the full reduction of sulfur during battery discharge (S8 + Zn2FeII(CN)6 ↔ ZnS + Zn1.5FeIII(CN)6, ΔG = -24.7 kJ mol-1). The open iron redox species render a lower energy barrier to ZnS activation during the reverse charging process, and the facile Zn2+ intercalative transport facilitates highly reversible conversion between S and ZnS. The yolk-shell structured cathode with 70 wt % sulfur delivers a reversible capacity of 1205 mAh g-1 with a flat operation voltage of 0.58 V, a fade rate over 200 cycles of 0.23%/cycle, and an energy density of 720 Wh kgsulfur-1. A range of ex situ investigations reveal the degradation nature of Zn-S cells: aggregation of inactive ZnS nanocrystals rather than the depletion of Zn anode. Impressively, the flexible solid-state Zn battery employing the composite cathode was assembled, realizing an energy density of 375 Wh kgsulfur-1. The proposed redox electrocatalysis effect provides reliable insights into the tunable Zn-S chemistry.

FEASIBILITY STUDY ON REVERSE CHARGING OF NEW ENERGY VEHICLE BATTERIES IN THE CONTEXT OF CARBON PEAK AND NEUTRALITY GOALS

In the search for green and sustainable development today, a good model of development for society is using social resources reasonably. According to the exploration of the supply and demand of electricity and the development trend of the new energy vehicle market, we have developed a feasibility study on the reverse charging of new energy vehicle batteries. By the study, we will use the new energy vehicle as an energy storage medium to regulate the supply and demand of the electricity market, establishing a systematic regulation network and leading the development of related industries and promoting the concept of resource conservation and green and sustainable development together all the time on the strategy of carbon peak and neutrality goals

An approach to the transformer core residual magnetism evaluation and demagnetization

Aiming at the problem of transformer inrush current suppression, a method of transformer core residual magnetism evaluation and demagnetization is proposed. Firstly, by setting the amplitude and time of DC current, different transformer core residual magnetism states are obtained. Secondly, under different residual magnetism conditions, the high-voltage winding of the transformer is charged and discharged in the forward and reverse direction alternately. The current change data in the process is collected, and the correlation coefficient of the current data in the forward and reverse charging processes is calculated, which represents the transformer core residual magnetism states. Finally, the DC current with alternating change direction and gradually decreasing amplitude is applied at the high voltage winding to demagnetize, and the variation of residual magnetism is analyzed during the demagnetization process.

Improved incentive pricing-based quasi-linear utility function of wireless networks

The model of the incentive pricing scheme-based quasi-linear utility function in wireless network was designed. Previous research seldom focusses on user’s satisfaction while using network. Therefore, the model is then attempted to be set up that is derived from the modification of bundling and models of reverse charging and maintain the quality of service to users by utilizing quasi-linear utility function. The pricing schemes then are applied to local data server traffic. The model used is known as mathematical programming problem that can be solved by LINGO 13.0 program as optimization tool to get the optimal solution. The optimal results show that the improved incentive pricing can achieve better solution compared to original reverse charging where the models will be obtained in flat fee, usage-based, and two-part tariff strategies for homogeneous consumers.

Numerical simulation of coke collapse and its optimization during burden charging at the top of bell-less blast furnace

Coke collapse is very important in blast furnaces as it determines the ore-to-coke ratio and further affects the gas utilization and CO2 emissions. Therefore, a three-dimensional model considering three types of ores and burden matrix charging of a bell-less top blast furnace is established using the discrete element method (DEM). The effects of reverse charging, coke platform width, central coke charging, and pellet ratio are investigated. The results show that reverse charging decreases the amount of coke collapse and improves the radial ore-to-coke distribution. A central coke charging as low as 5 wt% significantly reduces the coke collapse and improves the radial burden distribution. The platform width is recommended to be larger than 2 m with a pellet ratio no larger than 40% to improve the ore-to-coke ratio distribution.

Models of improved multilink reverse charging network by utilizing the bit error rate QoS attribute

<span>In this paper, a modification model for single-link reverse charging of internet is formed on a multi-link wireless network. The pricing scheme also takes into account the base costs and quality of services provided by the service provider. Bit error rate (BER) was utilized as one of the well-known quality of service (QoS) attribute that can guarantee best performance for internet service provider (ISP) and users. The base price is determined as a decision variable to help ISP to maximize profit. This optimization model can be solved using the LINGO 13.0 program to gain optimal values. The computational results show that by setting costs as constants and service quality as variables, optimal results are obtained for ISPs. This can make ISP considerations in determining the base price that can benefit the ISP and according to the services provided</span>.

High‐Capacity and Stable Sodium‐Sulfur Battery Enabled by Confined Electrocatalytic Polysulfides Full Conversion

AbstractThe efficient polysulfide capture and reversible sulfur recovery during reverse charging process are critical to exploiting the full potential of room temperature NaS batteries. Here, based on a core‐shell design strategy, the structural and chemical synergistic manipulation of sodium polysulfides quasi‐solid‐state reversible conversion is proposed. The sulfur is encapsulated in the multi‐pores of 3D interconnected carbon fiber as the core structure. The Fe(CN)64−‐doped polypyrrole film serves as a redox‐active polar shell to lock up polysulfides and promote complete polysulfide conversion. Importantly, the short‐chain Na2S4 polysulfides are reduced to Na2S directly leaving with a small fraction of soluble intermediates as the cation‐transfer medium at the core/shell interface, and freeing up formation of solid Na2S2 incomplete product. Further, the redox mediator with open Fe species electrocatalytically lowers the Na2S oxidation energy barrier and renders the high reversibility of electrodeposited Na2S. The tunable quasi‐solid‐state reversible sulfur conversion under versatile polymer sheath greatly enhances sulfur utilization, affording a remarkable capacity of 1071 mAh g−1 and a stable high capacity of 700 mAh g−1 at 200 mA g−1 after 200 cycles. The confined electrocatalytic effect provides a strategy for tuning electrochemical pathway of sulfur species and guarantees high‐efficiency sulfur electrochemistry.

End-to-End Delay QoS Attribute-Based Bundling Strategy of Wireless Improved Reverse Charging Network Pricing Model

In this article, a multi-link internet reverse charging (IRC) scheme model in a multi-service network with the addition of a bundling strategy is proposed. Reverse charging schemes in multi-link and multi-service networks are rarely discussed in previous studies. This financing scheme is designed with the aim of maximizing service provider profits by minimizing internet usage costs. The basic cost and satisfaction level of the service provided by the ISP is focused on this effort. The model formed in this study is a Mixed Integer Non-Linear Programming (MINLP) model that is completed using software LINGO 13.0. This problem comprises two cases, when α case as a parameter and β as a parameter and or variable with sub–cases increases in usage based financing schemes. Thus, the results obtained can be a consideration for ISPs in determining the price of services that can support an ISP. The updated IRC model provides a more optimal solution than the original IRC model.

The improved model of incentive-pricing of internet schemes for Cobb-Douglas utility function by using LINGO 13.0

In this paper, an improved model of the incentive-pricing scheme was designed. Previous research only shows the incentive model with the disadvantages of no considering the utility function to measure the satisfaction of the user. Then, the models are improved by deriving from the incorporation of bundling and reverse charging models obtained from previous studies, as well as taking into account the quality of service to users by using the Cobb-Douglas utility function. Optimal pricing schemes applied to the local data server, which is mail traffic data. The model used is the nonlinear optimization problem and solved by LINGO 13.0 to get the optimal solution. The results show that optimal results in the form of pricing schemes by applying flat fee, usage-based, and two-part tariff for homogeneous consumer’s schemes and the improved models show better performance in achieving the profit than the previous incentive pricing models.

Modified Activated Carbon Fiber Felt for the Electrosorption of Norfloxacin in Aqueous Solution

As an antibiotic, Norfloxacin (NOR) is widely found in the water environment and presents considerable harm to human beings. At present, the preparation of removal materials is complicated, and the removal efficiency is not high. The adsorption effect of modified activated carbon fiber felt (MACFF) electrosorption and its influencing factors on NOR were studied. Activated carbon fiber felt (ACFF) was modified with 20% nitric acid, and the ACFFs were characterized by SEM, TEM, and FTIR both before and after modification. The optimal working conditions for electrosorption with an MACFF electrode were as follows: the voltage was 1.0 V, the pH was 6, and the plate spacing was 10 mm. The maximum adsorption capacity of the MACFF for NOR was 128.55 mg/g. Model fitting showed that pseudo-second-order kinetic model and Langmuir model were more suitable for explaining this adsorption process. In addition, this study found that, with 20% nitric acid as the regeneration liquid and under the reverse charging method, the regeneration rate of the MACFF electrode was maintained at approximately 96% and the regeneration was good, therefore, this technology can not only save operation costs but also has good development prospects in sewage treatment.

Mathematical model of improved reverse charging of wireless internet pricing scheme in servicing multiple QoS

This paper seeks to utilize the improved model of reverse charging scheme. Reverse charging basically is defined as a capability of stored network that replaces the network used when the network is suddenly shut down. In this paper, charging back on 3G and 4G network that is user automated platform, will change the access of 4G to 3G and on the contrary when platform conduct the hosting. This research was solved as a problem Mixed Integer Nonlinear Programming (MINLP) by LINGO 13.0. An optimal pricing scheme is applied to a local data server, including digilib traffic and mail traffic. The improved model of Reverse Charging is modified into 4 cases and formed by setting the base price (α) and service level (β). Based on the analysis that has been done, the results of this study indicate that the reverse charging model can be utilized Internet Service Provider (ISP) to maximize profits and provide quality services for the user if compared to previous model without reverse charging scheme. Keywords: improved model of revere charging scheme, MINLP, ISP, QoS, pricing scheme

Improved Multi Service-Reverse Charging Models for the Multi Link Internet wireless Using QOS Bit Error Rate QoS Attribute

n this article, a multi-link internet reverse charging scheme model on a multi-service network isproposed. The previous research seldom discussed the reverse charging scheme on multi linkand multi service network. This pricing scheme is designed with the aim of maximizing serviceprovider profits. Basic costs and the level of service satisfaction provided by the ISP is focusedon this attempt. This optimization problem can be solved using LINGO 13.0 software. Thisproblem was made and was divided into several cases. Thus, the results obtained can be aconsideration for ISPs in determining the price of services that can support an ISP. The improvedmodels that produce the maximum solution is case 3 (α and β as variables) and case 4 (α asvariables and β as parameters).

Resource Allocation Strategy for D2D-Assisted Edge Computing System With Hybrid Energy Harvesting

Due to the limited battery capacity and computing capability of mobile users, the resource allocation strategy in device-to-device (D2D)-assisted edge computing system with hybrid energy harvesting is investigated in this paper. By employing magnetic induction-based wireless reverse charging technology, mobile user can supplement extra energy from nearby users when the energy harvested from ambient radio frequency sources is about to be exhausted. Moreover, mobile user can not only perform local computation, but also offload computing tasks to nearby users for auxiliary computation through D2D communication links or mobile edge computing (MEC) server under base station (BS) for edge computation. Due to the limited computing resources of MEC server, when the computing capability of the MEC server reaches the maximum value, an adjacent user under another nearby BS can be considered as a relay node. The computing tasks of the remaining users under the previous BS can be transferred to the MEC server with sufficient resources under another nearby BS by establishing D2D relay links. The objective of the resource allocation strategy is to maximize the energy efficiency under the constraints of computation delay and energy harvesting. The resource allocation problem is formulated as a mixed-integer nonlinear programming problem, which is not easy to obtain the optimal solution at low computational complexity. A suboptimal solution is obtained by adopting the quantum-behaved particle swarm optimization (QPSO) algorithm. Simulation results show that the performance of the proposed strategy is superior to other benchmark strategies, and QPSO algorithm can achieve higher energy efficiency than the standard particle swarm optimization algorithm.

Analysis of Diode Reverse Recovery Effect on ZVS Condition for GaN-Based LLC Resonant Converter

LLC resonant converter can achieve zero voltage switching (ZVS) for primary-side devices and zero current switching (ZCS) for secondary-side rectifiers. However, the reverse recovery and junction capacitance ( Cj ) of secondary-side diode critically affect the ZVS condition of primary-side switches. The effect of Cj has been discussed in literature, but not the reverse recovery. In this paper, the reverse recovery charge ( Q rr) is converted to an equivalent capacitance $(C_{{\rm rr}\_{\rm eq}})$ for the study of primary-side ZVS performance. An accurate model during deadtime is derived and further applied to characterize ZVS performance with different reverse recovery charges in different regions. The concept of establishing parameter C total to consider both Cj and $C_{{\rm rr}\_{\rm eq}}$ is proposed to evaluate the effect of the secondary-side rectifiers. This concept provides the guideline for diode and synchronous rectification mosfet selection to ensure ZVS condition for LLC converters. To verify the concept and the derived model, a 200/400 V 400 W LLC resonant converter prototype operating from 200 to 700 kHz is built and its ZVS performances with different diodes are compared. Two issues caused by Q rr effect, including $V_{\rm ds}$ reverse charging and asymmetrical waveform during deadtime, are explained thoroughly as well.

Nanoparticle charging with mixed reverse micelles in apolar media

The charging of colloidal particles using mixed surfactants in apolar media is investigated. Previous work has shown that one can predict the sign and magnitude of particle charge by comparing the acid-base properties of an oil-soluble surfactant to the acid-base properties of a specific particle. The present work sought to tune the acid-base properties by using mixed surfactants. Unexpected mineral oxide particle charging results were obtained however, from mixing the acidic surfactant sorbitan monooleate (SPAN 80), with the basic surfactant polyisobutylene succinimide (OLOA 11000), requiring further investigation into the mixed reverse co-micelle particle charging mechanism. Conductometric titrations and small-angle neutron and x-ray scattering measurements showed that the surfactant mixtures formed spherical reverse co-micelles. Quartz crystal microbalance adsorption measurements demonstrated that both surfactants can adsorb to the particle surface. Lastly, electrophoretic mobility measurements showed that the surfactant mixture produced negative particle charging for nearly all surfactant ratios, and a greater magnitude of negative charging than that produced by the OLOA 11000 surfactant alone. It was discovered that in the mixed surfactant system studied, the basic surfactant would charge the hydroxyl groups on both the oxide surface, and the adsorbed acidic surfactant head groups. The results showed that particle charging behavior in apolar media using mixed micelles requires knowledge beyond that for the individual surfactants and their proportions in the mixture.

Simulation Study of a Low Switching Loss FD-IGBT With High <inline-formula> <tex-math notation="LaTeX">$dI/dt$ </tex-math> </inline-formula> and <inline-formula> <tex-math notation="LaTeX">$dV/dt$ </tex-math> </inline-formula> Controllability

In this brief, a novel floating dummy insulated gate bipolar transistor (FD-IGBT) is proposed and investigated by simulation. A floating n region and a p+ region shorted with an emitter in the floating p-base region are introduced to form an open-base transistor, and the voltage of the floating p-base region can be clamped by this transistor. In the turn-ON transient, the pile-up of holes in the floating p-base region increases its quasi-Fermi potential and leads to punch-through of the floating n region at a low voltage, which in turn clamps the voltage of the floating p-base region, decreasing the Miller capacitance and thereby the reverse gate charging current from the floating p-base region to the gate. As a result, the proposed FD-IGBT demonstrates not only dramatically reduced turn-ON energy loss for the lower Miller capacitance but also excellent controllability on $dI_{\text {CE}}$ / dt and $dV_{\text {CE}}$ / dt , and hence on the reverse recovery $dV_{\text {KA}}$ / dt of the free-wheeling diode (FWD) for the lower reverse gate charging current. TCAD simulation results indicate that, for the same ${E}_{ \mathrm{\scriptscriptstyle ON}}+{E}_{ \mathrm{\scriptscriptstyle OFF}}$ of 90.8 mJ/cm2, $dI_{\text {CE}}$ / dt of the proposed IGBT and the reverse recovery $dV_{\text {KA}}$ / dt of FWD are decreased by 87.7% and 58.2%, respectively, compared with the conventional one.

Piezoelectric property improvement of polyethylene ferroelectrets using postprocessing thermal‐pressure treatment

In this work, biaxially stretched polymer foams with well‐defined cellular structures were prepared from polyethylene via blown‐film extrusion and subjected to corona charging to produce a piezoelectric response. The charging parameters were first optimized in terms of charging voltage and needle distance, as well as the gas type and pressure to investigate their effect on the piezoelectric coefficient (d33). The results show that samples charged under nitrogen (N2) at 100 kPa had better d33 coefficient than those charged under ambient air or N2 at 20 kPa. Moreover, 2 different thermal pressure treatments were imposed to obtain an optimized eye‐like cellular structure with different cell aspect ratios (AR). The results showed that when the cells were elongated in both the longitudinal and transverse directions (higher AR), higher d33 coefficients were achieved. From all the samples produced, the best results were obtained for a longitudinal aspect ratio (AR‐L) of 7.1, a transversal aspect ratio (AR‐T) of 4.6, and a relative foam density of 0.52 leading to a d33 coefficient of 935 pC/N. This coefficient was further increased using reverse charging and multilayered films, reaching a maximum of 2550 pC/N. This value is much higher than typical ones reported so far for any polyethylene and polypropylene ferroelectrets. These results could increase the use of polyethylene in piezoelectric applications as these materials are very attractive for the large‐scale production of electret‐based sensors and transducers due to their low cost and easy processing.

Improved Fault-Tolerant Method and Control Strategy Based on Reverse Charging for the Power Electronic Traction Transformer

Power electronic traction transformer (PETT) is a new topology for a traction drive system, which can realize the high voltage and power conversion through multilevel converters and high-/medium-frequency transformer link. Reliability becomes a key issue for PETT adopting the module-cascaded structure. In this paper, an improved fault-tolerant method based on reverse-charging control of dual active bridge is proposed, which is suitable for PETT and other two-stage structure converters. The control strategy and operating process of an improved fault-tolerant method are introduced. Comparisons among improved and traditional fault-tolerant methods are also presented. Simulation and experimental results are provided to show the correctness and effectiveness of the improved fault-tolerant method.