Specific Discharge Conditions Research Articles

Arrhenius Equation-Based Model to Predict Lithium-Ions Batteries’ Performance

The accuracy of Peukert’s battery capacity equation may decrease under the conditions of variable current and variable temperatures. Some researchers have previously tried to overcome the lack of C-rate change. However, the dependence of battery capacity on temperature is still not included. In this paper, we mainly studied the capacity reduction effect of batteries under variable temperatures. The proposed method can calculate the battery’s available capacity according to the specific discharge conditions. The experimental method proposed in this paper provides a reasonable test method to generate the required coefficients in order to establish a state of charge prediction model with high accuracy. After establishing the method, we can make a real-time prediction of the available energy of battery including the remaining energy of battery. From the result, we can see that the result is of great precision and the method is valuable.

Measurement of negative ion fluxes during DC reactive magnetron sputtering of Ti in Ar/O2 atmosphere using a magnetic-filtering probe

The flux of negative oxygen ions in a dc reactive magnetron discharge has been measured using a specially developed magnetic-filtering probe. The gridded probe which operates as a retarding field analyzer has a magnetic filter attached to the front entrance to suppress plasma electrons entering the device. As a result, the fluxes of unmagnetized negative ions with energies of higher than ~10 eV can arrive to an ion collector and contribute to the detected probe current. During the oxide mode of Ti–Ar/O2 magnetron sputtering discharge, the measured negative ion flux is considered to be contributed by the sputtered O− ions generated at the target surface and the plasma O− ions created in the discharge volume. However, in specific discharge conditions, the sputtered ions are likely to dominate in the measured flux signal. As a result, the yield of the sputtered O− ions and associated energy flux can be examined. The magnetic-filtering probe could potentially be employed as a real-time diagnostic tool to monitor the sputtered O− flux as well as the oxide state of the target surface during reactive magnetron sputtering processes.

Experimental investigations of the effect of the neutral gas pressure on the separate control of ion energy and flux in dual frequency capacitively coupled plasmas

Classical dual-frequency capacitively coupled plasmas (2f CCPs) operating at low pressures and significantly different frequencies are often used for a variety of applications in semiconductor manufacturing in order to control the mean ion energy at the electrodes separately from the ion flux. However, recent computational studies have indicated that this separate control is limited by the frequency coupling effects and by the contribution of secondary electrons to the ionization dynamics [Donkó et al., Appl. Phys. Lett. 97, 081501 (2010); Schulze et al., Plasma Sources Sci. Technol. 20, 045007 (2011)]. Here, we verify these simulation results experimentally by measuring the ion flux to an electrode as a function of the low frequency (LF) and high frequency power at different neutral gas pressures in a 2f CCP operated at 2.26 MHz and 13.56 MHz in argon. In agreement with previous computational predictions, we find the ion flux to decrease as a function of the LF power at a low pressure of 1 mTorr due to the frequency coupling and to increase as a function of the LF power at a higher pressure of 60 mTorr due to the presence of secondary electrons. These experimental findings show that separate control of ion properties in classical 2f CCPs is generally not possible, but potentially limited to specific discharge conditions.

Thermal Model of Cylindrical Lithium Ion Batteries

Due to their characteristic of providing high energy density and long cycle life, Li-ion batteries are being widely used as power sources for a range of applications, including electric vehicles. The temperature of a Li-ion cell is important for its performance, capacity, efficiency and safety, and it is strongly influenced by the charging and discharging process modalities. Especially during electric vehicle operation, considerable heat is generated in the battery pack that needs to be removed. In the present paper a simplified model for predicting the temperature trend within a battery module with cylindrical cells, is presented. This allows to estimate the requirements for a given cooling system under specific discharge conditions. Three cooling fluids have also been experimentally compared: air, a dielectric oil and a perfluorinated polyether. The best performance was shown by a commercial perfluorinated polyether, by which it was possible to work in safe conditions with a very low pumping power: at 0.02 W, a maximum temperature of 48°C is reached at the end of the discharge using Galden HT135, while 55°C is reached with the Midel ICE. The results also showed that, under the assumed conditions, an air-cooling system needs between 100 and 1700 times more energy than the other methods to keep the same average temperature.

Remaining Useful Life Prediction of Lithium-Ion Batteries Using Neural Network and Bat-Based Particle Filter

Predicting the remaining useful life (RUL) is an effective way to indicate the health of lithium-ion batteries, which can help to improve the reliability and safety of battery-powered systems. To predict the RUL, the line of research focuses on using the empirical degradation model followed by the particle filter (PF) algorithm, which is used for online updating the model’s parameters. However, this works well for specific batteries under specific discharge conditions. When the degradation trends cannot be presented by the chosen empirical model or the standard PF encounters impoverishment and degeneracy problem, the RUL prediction would be inaccurate. To improve the RUL prediction accuracy, we propose a novel approach by enhancing the existing method from two aspects. First, we introduce a neural network (NN) to model battery degradation trends under various operation conditions. As NN’s generalization and nonlinear representing ability, it outperforms the typical empirical degradation model. Second, the NN model’s parameters are recursively updated by the bat-based particle filter. The bat algorithm is used to move the particles to the high likelihood regions, which optimizes the particle distribution and thus reduces the degeneracy and impoverishment of PF. In this paper, quantitative evaluation is presented using two datasets with different batteries under different aging conditions. The results indicate that the proposed the approach can achieve higher RUL prediction accuracy than conventional empirical model and standard PF.

Turbulence characteristics of 45° inclined dense jets

In the present study, we performed an extensive laboratory investigation to quantify the turbulence characteristics of 45° inclined dense jets using Particle Image Velocimetry (PIV) over a wide range of Densimetric Froude Number. The objective was to provide benchmark data to guide high resolution turbulence numerical simulations for dense jets in the future. The PIV measurements were sampled at a relatively high frequency of 50 Hz, which enabled the analysis of second order turbulence statistics as well as the turbulence kinetic energy spectrum (including the inertial subrange) along the curvilinear jet trajectory, which has hitherto not been reported. The measurements showed that the spectral profile was flat near the discharge port with the potential core, since the Kelvin–Helmholtz shear-induced turbulence at the jet boundaries had not fully penetrated to the core. The spectral profile then evolved along the trajectory with progressive steepening towards the higher frequencies, and a fully-developed profile appeared beyond the terminal rise with a clearly identifiable inertial subrange for the energy cascade. In parallel, we also performed numerical simulations using the Large Eddy Simulations (LES) approach with the Dynamic Smagorinsky sub-grid model for the specific discharge conditions as in the experiments. The LES approach followed that of Zhang et al. (Environ Fluid Mech 16(1):101–121, 2016, J Hydro Environ Res 15:54–66, 2017) using GCI as the grid convergence criteria. The comparison showed that the time-averaged first order mixing characteristics of the inclined dense jet can be simulated reasonably well comparing to the experimental data. In terms of the turbulence kinetic energy spectrum, the low frequencies of the production range were also well captured by the simulations. However, the simulated transitional spectra towards the inertial subrange decayed substantially faster than the experiments. The discrepancy was attributed to the fact that the grid resolution was not sufficiently fine in the simulations (which were constrained by the available computational resources and time), such that stratified effects remained present inside the sub-grids producing additional turbulence energy that were not represented by the Dynamic Smagorinsky model. Thus, the numerical investigation showed that further improvement in sub-grid models that can incorporate the stratified effects would be desirable in the future for engineering simulations.

Surface-wave-sustained plasma torch for water treatment

In this study the effects of water treatment by surface-wave-sustained plasma torch at 2.45 GHz are studied. Changes in two directions are obtained: (i) changes of the plasma characteristics during the interaction with the water; (ii) water physical and chemical characteristics modification as a result of the plasma treatment. In addition, deactivation of Gram positive and Gram negative bacteria in suspension are registered. A number of charged and excited particles from the plasma interact with the water. As a result the water chemical and physical characteristics such as the water conductivity, pH, H2O2 concentration are modified. It is observed that the effect depends on the treatment time, wave power, and volume of the treated liquid. At specific discharge conditions determined by the wave power, gas flow, discharge tube radius, thickness and permittivity, the surface-wave-sustained discharge (SWD) operating at atmospheric pressure in argon is strongly non-equilibrium with electron temperature Te much higher than the temperature of the heavy particles (gas temperature Tg). It has been observed that SWD argon plasma with Tg close to the room temperature is able to produce H2O2 in the water with high efficiency at short exposure times (less than 60 sec). The H2O2 decomposition is strongly dependant on the temperature thus the low operating gas temperature is crucial for the H2O2 production efficiency. After scaling up the device, the observed effects can be applied for the waste water treatment in different facilities. The innovation will be useful especially for the treatment of waters and materials for medical application.

Observation on fundamental and second harmonic mode ECRH assisted plasma startup in SST-1 experiments

In SST-1, successful plasma startup has been achieved at very low loop voltage with the help of ECRH pre-ionization. ECRH is operated in both O mode and X mode for the purpose of pre-ionization at the pre fill pressure of 1×10−5mbar. A delay in breakdown has been observed in case of second harmonic ECRH pre-ionization; where in case of fundamental mode of ECRH pre-ionization, the instant breakdown has been observed. This work has attempted at explaining the non-linear interaction of the seed electrons with the electromagnetic field of the incident ECRH wave that has led to break down of the plasma. The delay in the break down attributes to the time differential between the applications of the ECRH pulse to that of the appearance of the H-alpha signal in SST-1. The observed experimental results have been discussed in this paper from the first principles and numerically solving the electron-ECRH field interactions resulting in energy gains of the electrons leading to plasma break down in SST-1 specific discharge conditions.

Expanding the Peukert equation for battery capacity modeling through inclusion of a temperature dependency

The accuracy of Peukert's equation for battery capacity lessens under dynamic loading and varying temperature conditions. Previous attempts by others endeavor to overcome the current shortfall; however, many still neglect the inclusion of a temperature dependency. This paper investigates the feasibility of Peukert's equation for practical automotive situations and expands upon the equation in order to include both variable current and temperature effects. The method proposed captures these requirements based on the theory that a battery contains a relative maximum absolute capacity, different from manufacturer 20-h specifications, and the specific discharge conditions determine the rate at which to remove this capacity. Experimental methods presented in the paper provide an economical testing procedure capable of producing the required coefficients in order to build a high-level, yet accurate state of charge prediction model. Finally, this work utilizes automotive grade lithium-based batteries for realistic outcomes in the electrified vehicle realm.

Characterization of transient discharges under atmospheric-pressure conditions applying nitrogen photoemission and current measurements

The plasma parameters such as electron distribution function and electron density of three atmospheric-pressure transient discharges namely filamentary and homogeneous dielectric barrier discharges in air, and the spark discharge of an argon plasma coagulation (APC) system are determined. A combination of numerical simulation as well as diagnostic methods including current measurement and optical emission spectroscopy (OES) based on nitrogen emissions is used. The applied methods supplement each other and resolve problems, which arise when these methods are used individually. Nitrogen is used as a sensor gas and is admixed in low amount to argon for characterizing the APC discharge. Both direct and stepwise electron-impact excitation of nitrogen emissions are included in the plasma-chemical model applied for characterization of these transient discharges using OES where ambiguity arises in the determination of plasma parameters under specific discharge conditions. It is shown that the measured current solves this problem by providing additional information useful for the determination of discharge-specific plasma parameters.

四万十川源流部の森林における降雨時の硝酸態窒素流出特性

The characteristics of NO3--N cumulative specific load during stormy flood events were investigated in a forested, mountainous headwater catchment of Shimanto River basin, located at the southwestern part of Shikoku Island, Japan. The vegetation in the catchment was a natural forest. Seventeen flood events were investigated. The intercept of the regression line between the cumulative specific discharge and the NO3--N cumulative specific load in term A (from the end of the rainy season in July through September) was significantly different from that in term B (other than term A) (p < 0.01). The slope of the line was smaller (approximately 0.8) than those in previous studies (greater than 1). NO3--N in surface soil (0 to 5 cm depth from the surface) was most abundant in August, and less in winter and spring than in summer. It was considered that NO3--N in surface soil increased owing to active mineralization and nitrification in summer. These results indicated that the NO3--N cumulative specific load under the same cumulative specific discharge conditions tends to increase in summer, and that the increase rate of the NO3--N cumulative specific load relative to cumulative specific discharge tends to decrease in the studied catchment.

Electrode wear-compensation of electric discharge scanning process using a robust gap-control

Robust gap-control is applied to compensate for electrode wear in an electric discharge scanning (ED-Scanning) process. This control compensates for the wear without reference to the wear ratio of the electrodes. An auxiliary gap-control loop in the vertical direction can compensate for the wear of the electrode, according to the discharge voltage when the electrode is driven along the two horizontal axes. A proportional controller for a gap-control system with maximal robustness is designed and robustly analyzed to override the non-linear and time-varying feedback. The simulated and practical responses of such a robust gap-control system yield favorable performances. The controller can maintain the location of the discharge on the vertical axis and fix the depth of the removal to that of a particular layer. The practical scanning process reveals that the dimension of a hole can be guaranteed only if the data concerning the depth of removal under specific discharge conditions and electrode diameters are applied.

Suppression of gas species signals in direct current glow discharge time-of-flight mass spectrometry

The possibility of suppressing gas species in direct current glow discharge mass spectrometry (dc-GDMS) with a linear time-of-flight mass analyzer was investigated. With this dc-GD ion source, a ‘clean’ mass spectrum rich in analyte could be obtained when the dc-GD was operated under a discharge current of 15–30 mA and a gas pressure of 300–500 Pa, in contrast to the strong signals of gas species in conventional dc-GDMS, which operates at lower currents and pressures (typically 1–5 mA and 100 Pa). Such an experimental result is believed to be due to increased sputtering at higher pressures and currents, and the different ionization mechanisms of analyte and gas species. For a possible GD design to eliminate the background gas ions, a new discharge configuration was developed by attaching a TM 010 microwave resonator to the GD ion source. The mass spectrum of the cathode sample showed a low gas species background when the microwave-induced plasma (MIP) discharge was ‘off’ under different dc-GD parameters. The mass spectra of analyte and gas species obtained with ‘MIP+dc-GD’ and ‘MIP only’ modes are also compared and discussed. It was found that the analyte signals decrease and the gas species signals increase in the presence of the MIP, and that the analyte signals nearly disappear in the ‘MIP only’ mode. Preliminary results suggest that, for specific discharge conditions and with a suitable design of the GD source, an efficient suppression of gas species in dc-GDMS detection could be realized.

Cathode sputtering with electrical discharge through a heavy water-saturated vapor interface

An experimental study of electrical discharge in an atmosphere of heavy-water vapor was conducted. The heavy-water surface served as the cathode. Under specific discharge conditions, intense neutron radiation induced by the discharge was observed. The dependence of the intensity of neutron generation on the discharge current was measured.

MIXING INDUCED BY AN INTERNAL HYDRAULIC JUMP1

ABSTRACT The efficiency of an inverted internal hydraulic jump as a mixing and dispersion mechanism in an aquatic environment was examined. The flow considered was a two‐dimensional buoyant flow from a shallow channel over a sloping bottom into a deep reservoir. It could be seen that a rapidly varied flow associated with violent turbulent mixing occurred near the point of discharge if specific discharge conditions and downstream controls were met. Downstream from the mixing zone the flow was stably stratified. The main object of the study was to find the conditions under which a turbulent mixing zone occurred and the rate of turbulent entrainment. Energy loss and length of the mixing zone were also investigated. The independent variables were the outlet densimetric Froude number, the density differential between outfall water and receiving water, the relative depths of the upper and lower layers in the stratified flow portion, the total depth, and the slope of the transition. Theoretical calculations had to be confined to a step increase in depth, but experiments in a laboratory flume showed that results obtained with slopes of 23° and 90° were quite similar. Both theory and experiments showed, for example, that dilution (entrainment rates) up to 2:1 (2 parts heated water to one part cold water) can be achieved at very little energy expense and with downstream depths approximately 8 times the outlet depth. Theoretically, any amount of dilution can be obtained, but large depths may be required. Experimental results also indicate that the length of the mixing zone was frequently ten times the value of the outlet densimetric Froude number.

Studies on protein-like products from radiofrequency plasmas of CO, N 2 and H 2

Solid protein-like products have been produced from “cold” plasmas of the inorganic gases CO, N 2, and H 2 reacting under specific discharge conditions. The excitation of gases under electrodeless radiofrequency (13.56 MHz) conditions produced polymers whose chemical composition was tailorable as a function of gas flow rates. The polymers on hydrolysis showed the presence of alanine, glutamic acid, glycine, serine, and tyrosine as the most common hydrolysate amino acids. Many other compounds of unknown structure are shown to be separable by two-dimensional thin-layer chromatography. These compounds can be quite complex, and may be polymeric, or heterocyclic in nature. Presence of aromatic systems has been unequivocally established for sym. trimethylpyridine and strongly indicated for tyrosine. Possible reaction mechanisms leading to the synthesis of the glycyl unit are proposed, and the role of surfaces or other nucleation sites for condensation of products is discussed. A suggestion is presented whereby reactions between CO, N 2, and H 2 induced in primordial times by ultraviolet energy could have led to condensation of organic products on upper atmospheric dust particles.