Levels Of Charging Research Articles

Self-charging of sprays

The charging of poorly conducting liquids due to flows is a well-known phenomenon, yet the precise charging mechanism is not fully understood. This is especially relevant for sprays, where the spray plume dynamics and maximum distance travelled of a spray dramatically changes for different levels of charging: charging of the droplets makes them repel, thereby preventing drop coalescence and altering the shape of the spray plume. As the charging depends on many factors including the flow and the interactions between the liquid and the nozzle, many models and scaling laws exist in the literature. In this work we focus on perhaps the simplest flow regime, laminar jets created by ultra short channels, and quantify the charging as a function of the different parameters. We present a simple model that collapses all the data for over 4 orders of magnitude difference in streaming currents for various nozzle sizes, flow velocities and surface treatments. We further show that the charging polarity can even be reversed by applying an oppositely charged coating to the nozzle, an important step for any application.

Negative Electrospray Supercharging Mechanisms of Nucleic Acid Structures.

When sprayed from physiological ionic strength, nucleic acids typically end up with low levels of charging and in compact conformations. Increasing the electrospray negative charging of nucleic acids while preserving the native noncovalent interactions can help distinguish solution folds by ion mobility mass spectrometry. To get fundamental insight into the supercharging mechanisms of nucleic acids in the negative mode, we studied model G-quadruplex structures and single-strand controls in 100 mM ammonium acetate. We found that adding 0.4% of propylene carbonate, 0.4% of sulfolane, or 0.1% of m-NBA induces native supercharging. However, although 0.4% of m-NBA shows the highest supercharging ability, it induces unwanted unfolding of solution-folded G-quadruplexes. The supercharging effect resembles the effect of lowering the ionic strength, and this could be explained by partial neutralization of the ampholytes when droplets become more concentrated in their nonaqueous components. The supercharging ability ranks PC < sulfolane < m-NBA. m-NBA adducts to G-quadruplexes with high-charge states confirm that the supercharging agent interacts directly with DNA. Surprisingly, in the presence of supercharging agents, the most negatively-charged states also bear more alkali metal ion adducts. Larger droplets are known to result in more counterion adduction, so our results are consistent with native supercharging conditions producing larger droplets evaporating to a charged residue. However, when negative charge carriers from the electrolyte become too rare, chain ejection accompanied by denaturation, and hence non-native supercharging, can become predominant.

Impact of Electrostatic Perturbations on Proximity Operations in High Earth Orbits

A range of upcoming missions propose to rendezvous in high Earth orbits, including the geostationary orbit region. This region is known to periodically experience high levels of electrostatic charging, which can result in perturbing intercraft forces and torques during close-proximity operations on the order of tens of meters. A range of proximity operations with a nonoperational target are modeled to evaluate the impact of electrostatic force and torque perturbations as a result of spacecraft charging. Perturbing electrostatic torques are evaluated using the multisphere method and result in the target body rotating, requiring the servicer to maintain its relative position by translation. Electrostatic perturbations are found to be significant, with potentials on the order of 1000 V resulting in larger perturbing torques than solar radiation pressure for this model. Electrostatic perturbations exist even in cases where both spacecraft are at the same potential. Record charging conditions lead to target rotational rates over during a nominal rendezvous. Target rotations require increases in fuel consumption for rendezvous and proximity operations, over 10 times more than a solar radiation pressure-induced torque, and present additional challenges associated with maneuvering in proximity to a tumbling target in a highly coupled and nonlinear dynamic environment.

Comparative exergy analysis between rotary hearth furnace-electric arc furnace and blast furnace-basic oxygen furnace steelmaking routes

Resource fuel used in integrated steelmaking processes are different based on fuel availability consideration. A fuel-based comparative energy utilisation efficiency in integrated steel plants as obtained through exergy analysis for two steelmaking routes, namely, rotary hearth furnace-electric arc furnace (RHF-EAF) and blast furnace-basic oxygen furnace (BF-BOF) is presented with additional consideration of electrical energy input replacing fuel energy in EAF for RHF-EAF route. Initially, exergy flow models of sub-systems (BF, BOF, RHF and EAF) are established separately. These sub-system models are coupled together to analyse the exergy flows, exergy losses and exergy efficiencies of the two integrated steelmaking systems. Gas-based exergy efficiency based on input exergy of RHF-EAF steelmaking process is always found to be better than conventional BF-BOF process as well as BF-Tenova Flexible Modular Furnace system (a modified BF-BOF process having electric arc facility in BOF to increase the scrap percentage in BOF charge). However, BF-BOF processes are found to be superior to RHF-EAF process when metal-based exergy efficiencies are compared. Combined metal plus gas-based exergy efficiencies of RHF-EAF steelmaking process are marginally better than BF-BOF route. Efficiency of scrap reycle for both steelmaking routes has also been analysed through exergy efficiency parameters. It was found that exergy utlisation efficiency of RHF-EAF steelmaking process based on both products steel and total by-product fuel gas for hot charging of direct reduced iron (DRI) above 600°C is superior to BF-BOF steelmaking process for all levels of scrap charging in steel making. For hot charged DRI at 600°C in RHF-EAF steelmaking process, the combined exergetic efficiency based on metal and by-product fuel gas is around 75% compared to 67% of BF-BOF and modified BF-BOF steelmaking systems, indicating more efficient input fuel utlisation than both variants of BF-BOF route.

Effects of Polarization on Particle-Laden Flows.

Simulations of particle-laden flow with dielectric particles are carried out with varying levels of electrical charging and particle polarization. Simulation results reveal three distinct flow regions. For low particle charge and polarizability, flow is nearly symmetric and nonmeandering. For strong charging and polarization, particles form a continuous and tightly clustered sheet close to one of the walls. Between these extremes, particles form localized particle-rich regions, around which the gas executes a meandering flow. These results indicate that polarization can lead to qualitative changes in the characteristics of particle-laden flows subject to tribocharging.

A survey on power levels of battery charging and infrastructure for plug-in electric and hybrid vehicles

Hybrid electric vehicle is an integration of conventional internal combustion engine and electric propulsion systems. Hybrid electric vehicles have tempted many people as their mode of transport which is going to be the next biggest global market in the upcoming years due to lack of fuel based energy and emission from the exhaust that ultimately leads global warming. Hybrid electric vehicles reduce the overall cost of fuel and have good economic impact on the global society. The development of hybrid electric vehicle is fast picking up its pace to be the next generation of the mode of transport. This paper explains the overview of hybrid electric vehicles, classification of hybrid electric vehicle, battery chargers, charging level infrastructure, Issues and opportunities.

Design and Development of Three Levels Universal Electric Vehicle Charger Based on Integration of VOC and SPWM Techniques

In order to successfully launch Electric vehicles (EVs) over the actual world, EVs battery chargers have a crucial role to predict the charging time. This work presents the design process of a universal EV charger, The proposed charger is able of providing a controllable and constant charging voltage for a various EVs, which is composed of three levels of charging, 650 V/100 A DC for bus or lorry, single-phase 120 V/16 A AC for motorcycle, and three-phase 240 V/60 A for saloon car battery charging. The output voltage ranges are 40 V–60 V, 400 V–500 V, or 500 V–600 V. The power system of this work consists of two converters; First one, is for the three-phase pulse-width modulated (PWM) of a bridge rectifier with an output of 850 V DC unregulated voltage, while the second converter is for the three-phase DC–DC converter. To satisfy the voltage control and the isolation between Grid To Vehicle (G2V), a three-phase transformer has been exploited within the DC/DC converter. The primary output circuit achieved the charge levels one and two, while the whole circuit output can charge level three or the DC charge. For efficient and secure battery charging, voltageoriented control (VOC) technique is proposed. The unity power factor for the PWM-based rectifier and SPWM are designed and evaluated using MATLAB/Simulink block sets. The total harmonic distortion (THD) for the input current is less than 5%, while the overall simulation-based efficiency is more than 97%. A prototype and simulation results validate that the proposed EV charger is robust, accurate, and applicable.

Network Security and Privacy Challenges in Smart Vehicle-to-Grid

Smart vehicle-to-grid (V2G) involves intelligent charge and discharge decisions based on user operational energy requirements, such as desired levels of charging and waiting time. V2G is also supported by information management capabilities enabled by a secure network, such as a reliable privacy-preserving payment system. In this article, we describe the network security and privacy requirements and challenges of V2G applications. We present a new network security architecture to support V2G. We propose a scheme with the following security and privacy-preserving features: anonymous authentication, fine-grained access control, anonymous signatures, information confidentiality, message integrity, remote attestation, and a payment system. This article is oriented toward practitioners interested in designing and implementing secure and privacy-preserving networks for smart V2G applications.

Comparison of theory with experiment for single bubbles in charged fluidized particles

Previous numerical studies, focused on single bubbles, predicted that electrostatics can cause bubble elongation in gas-fluidized beds. However, there was a lack of experimental evidence to test the numerical predictions. This study compares experimental bubble size and shape in beds with two levels of charging. The results indicate that single bubbles are smaller and more elongated in a bed with higher charge density. Instability of bubble roofs for particles of high electrostatic charge density was also observed.The experimental results are in agreement with the previous simulation results, with uniform particle charge density in the lower part of the bed and differences in the upper part. New simulations allowing for spatial variation of charge density show that bubble shape and stability are functions of the particle charge density distribution. Differences between simulation and experimental results are likely due to non-uniform distribution of charge on particles.

Design and Numerical Assessment of a Passive Electron Emitter for Spacecraft Charging Alleviation

In this paper, we examine the theoretical basis for using passive unheated electron field emitters to control hazardous levels of spacecraft charging. We present the experimental evidence related to the capabilities of passive and low-power active field emitters. The concept of passive field emitters is detailed looking at their characteristics and location on a model satellite typical of a commercial geostationary satellite. The assessment is performed by means of numerical simulations. The generation and extraction of electrons is simulated at micrometric scale. Their flow is modeled at spacecraft scale to assess spacecraft absolute and differential charging alleviation. The system shows good promise limiting the inverted voltage gradient situations, observed especially on solar panels where cover glasses are more positive than solar cells. This situation is known as very risky in flight, possibly leading to sustained secondary arcing powered by the photovoltaic solar arrays themselves. Finally, we review how existing design practice would be modified by the presence of such passive emitters.

High-performance planar nanoscale dielectric capacitors

We propose a model for planar nanoscale dielectric capacitor consisting of a single layer, insulating hexagonal boron nitride (BN) stripe placed between two metallic graphene stripes, all forming commensurately a single atomic plane. First-principles density functional calculations on these nanoscale capacitors for different levels of charging and different widths of graphene - BN stripes mark high gravimetric capacitance values, which are comparable to those of supercapacitors made from other carbon based materials. Present nanocapacitor model allows the fabrication of series, parallel and mixed combinations which offer potential applications in 2D flexible nanoelectronics, energy storage and heat-pressure sensing systems.

Fragilização por hidrogénio no aço ABNT 10B22 modificado carbonitretado temperado e revenido a 400 °C

The hydrogen embrittlement is a problem that affects metallic structures causing a decrease in mechanical properties of materials, mainly by increasing brittleness and reducing toughness and strength. In the case of applications such as high strength bolts, which have suffered surface hardening treatment the hydrogen can be introduced into the material during the manufacturing process, particularly by steps of wet surface treatment methods. In this work was studied the permeation of hydrogen effects with different charging levels on samples of modified ABNT 10B22 steel. The samples were submitted to carbonitriding treatment, and then were quenched and tempered at 400°C. The specimens were subjected to the forced introduction of hydrogen through galvanostatic control in three levels of charging, and then pulled using the slow strain rate technique. The samples were morphologically characterized by scanning electron microscopy. Furthermore, it was determined the samples hardness profile. It was observed that, as the intensity of the hydrogen charging current increase, there is a reduction of mechanical properties of material, such as reduction of toughness, ultimate tensile strength (UTS) and ductility.

E2 ubiquitin-conjugating enzymes regulate the deubiquitinating activity of OTUB1.

OTUB1 is a Lys48-specific deubiquitinating enzyme that forms a complex in vivo with E2 ubiquitin conjugating enzymes including UBC13 and UBCH5. OTUB1 binds to E2~Ub thioester intermediates and prevent ubiquitin transfer, thereby non-catalytically inhibiting accumulation of polyubiquitin. We report here that a second role of OTUB1-E2 interactions is to stimulate OTUB1 cleavage of Lys48 polyubiquitin, and that this stimulation is regulated by the ratio of charged to uncharged E2 and by the concentration of Lys48-linked polyubiquitin and free ubiquitin. Structural and biochemical studies of human and worm OTUB1 and UBCH5B show that the E2 stimulates binding of the Lys48 polyubiquitin substrate by stabilizing folding of the OTUB1 N-terminal ubiquitin-binding helix. Our results suggest that OTUB1-E2 complexes in the cell are poised to regulate polyubiquitin chain elongation or degradation in response to changing levels of E2 charging and available free ubiquitin.

Intrinsic Line Shape of the Raman 2D-Mode in Freestanding Graphene Monolayers

We report a comprehensive study of the two-phonon intervalley (2D) Raman mode in graphene monolayers, motivated by recent reports of asymmetric 2D-mode line shapes in freestanding graphene. For photon energies in the range 1.53-2.71 eV, the 2D-mode Raman response of freestanding samples appears as bimodal, in stark contrast with the Lorentzian approximation that is commonly used for supported monolayers. The transition between the freestanding and supported cases is mimicked by electrostatically doping freestanding graphene at carrier densities above 2 × 10(11) cm(-2). This result quantitatively demonstrates that low levels of charging can obscure the intrinsically bimodal 2D-mode line shape of monolayer graphene. In pristine freestanding graphene, we observe a broadening of the 2D-mode feature with decreasing photon energy that cannot be rationalized using a simple one-dimensional model based on resonant inner and outer processes. This indicates that phonon wavevectors away from the high-symmetry lines of the Brillouin zone must contribute to the 2D-mode, so that a full two-dimensional calculation is required to properly describe multiphonon-resonant Raman processes.

A novel procedure employing laser ultrasound technique and simplex algorism for the characterization of mechanical and geometrical properties in Zircaloy tubes with different levels of hydrogen charging

In this research, a procedure employing a laser ultrasound technique (LUT) and an inversion algorism is reported for nondestructive characterization of mechanical and geometrical properties in Zircaloy tubes with different levels of hydrogen charging. With the LUT, guided acoustic waves are generated to propagate in the Zircaloy tubes and are detected remotely by optical means. By measuring the dispersive wavespeeds followed by the inversion algorism, mechanical properties such as elastic moduli and geometrical property such as wall-thickness of Zircaloy tubes are characterized for different levels of hydrogen charging. Having the advantages of remote, non-contact and point-wise generation/detection, the reported procedure serves as a competitive candidate for the characterization of Zircaloy tubes generally operated in irradiative and temperature-elevated environments.

Proper Pricing for Transport Infrastructure and the Case of Urban Road Congestion

For transport systems the issues of pricing, service quality, funding and investment in urban areas are inextricably interdependent. The paper first argues that no policy can be set for any of these aspects of transport in isolation from any other. Transport planners and urban policy-makers can choose to tolerate congestion, or build new capacity or introduce road user charging. These issues are explored and analysed in the context of London-Europe's most obviously resurgent city and the one with the most recent experience of road pricing in the form of the Congestion Charge. However, despite the evidence that in the centre, where it applies, the Congestion Charge has had broadly the effects economic theory would predict, there is still a growing problem for the rest of London and the UK caused largely by the combined effects of rising real incomes and the improving fuel efficiency of cars which reduces the impact of fuel taxes. This suggests a growing pressure for a national system of road pricing. To date 'prices', in the form of fuel duty (over £0.50 out of each £0.80 for a litre of fuel) have been set on the basis of historical precedent or political expediency. The paper sets out a regionally based model to analyse the implications of setting alternative levels of congestion charging and environmental taxes covering the whole of England. This includes modelling the implications for other transport modes and the net changes accruing to drivers and the Exchequer. Having presented the implications of some alternative policies, the paper discusses a number of the issues of political economy that would have to be resolved. While there seems to be little alternative to user charging in some form sooner or later, the sooner it can be introduced the more good it can do. However, the difficulties are real, less tractable than some people appear to believe and they have to be identified and dealt with. Perhaps the most significant unresolved problem is not the technical feasibility of such a system of national road pricing, but finding an appropriate, accountable and acceptable method for overseeing and administering the funds such a system would generate.

Room temperature electron tunneling and storage in a nanocrystalline silicon floating gate structure

By using capacitance–voltage and conductance–voltage measurements, we studied electron tunneling and storage in a nanocrystalline silicon (nc-Si) floating gate double-barrier structure (SiO 2/nc-Si/SiO 2), which is fabricated in situ by plasma oxidation and layer-by-layer deposition technique in a plasma enhanced chemical vapor deposition (PECVD) system. Frequency-dependent capacitance peaks due to electron resonant tunneling into quantum confinement energy levels of nc-Si dots and Coulomb blockade charging in nc-Si dots have been observed for the first time at room temperature in SiO 2/nc-Si/SiO 2 system by capacitance spectroscopy. Meanwhile, conductance plateau in the region of capacitance peaks are also observed due to charging effect in nc-Si dots. Experimental results are in agreement with theoretical evaluation based on the model of Coulomb blockade.

Room Temperature Resonant Tunneling and Coulomb Blockade in Nanocrystalline Si with Double SiO2

ABSTRACTWe studied electron resonant tunneling and Coulomb blockade in nanocrystalline Si (nc-Si) with double SiO2 barriers, which is fabricated in-situ in a plasma enhanced chemical vapor deposition system. In capacitance-voltage measurements, discrete capacitance peaks due to electron resonant tunneling into energy levels of nc-Si dots and Coulomb blockade charging in nc-Si dots have been observed at room temperature. For smaller dots, capacitance peaks are more distinct due to the stronger Coulomb blockade effect. Meanwhile, conductance plateau in the region of capacitance peaks are also observed due to the charging effect in nc-Si dots. Experimental results are in agreement with theoretical evaluation based on the model of Coulomb blockade.

6Li Magic Angle Spinning NMR Study of the Cathode Material LiNixMn2 − x O 4 : The Effect of Ni Doping on the Local Structure during Charging

magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy has been used to study the local structure of synthesized by solid-state reactions. When the extent of doping is small and 0.1), several resonances are observed, which are assigned to lithium local environments containing different numbers of and ions. As the doping level increases and the average manganese oxidation state rises, the intensity of the resonances assigned to lithium environments containing a greater number of higher-oxidation state manganese ions increases; this results in a gradual shift of the center of mass of the spectrum to higher frequency. By only ions are present, and only one major resonance, due to the lithium local environment is observed; this is consistent with Mn/Ni ordering on the octahedral sites of the spinel structure. The variable temperature NMR behavior of these samples is indicative of different magnetic behavior for the undoped and doped materials. A plot of shift) vs. temperature is consistent with the predominance of antiferromagnetic correlations for low doping level samples, while antiferromagnetic correlations clearly dominate the behavior of the sample, resulting in overall ferrimagnetic behavior. spectra were also collected following various levels of charging. In the case of is deintercalated from the different local sites sequentially: lithium ions in the local environment containing manganese ions with an average oxidation state of +3.5 are deintercalated first, followed by lithium ions in sites containing progressively more ions. In contrast, for where the deintercalation process involves oxidation of only, no changes in the lithium local environments were observed during the charging process: the shift position remained constant during the charging cycle and only a loss of the intensity of the lithium signal was observed. © 2001 The Electrochemical Society. All rights reserved.

Filtration of Electrified Solid Particles

The filtration of electrified solid particles in a fixed bed of sand was carried out. The particles were electrified by impacting them against an obstacle. This was done in a controlled way, so that several levels of charging could be attained. The collection of the charged particles took place in a cylindrical filter 0.15 m in diameter and three bed heights (0.01, 0.02, and 0.04 m) tall. Phosphatic concentrate particles with a mean diameter of 5.2 μm were utilized as the test powder. The results have shown that the presence of electrostatic charges can alter significantly the filtering behavior of the granular bed. The measured penetration of particles through the bed in the initial stages of the filtration was compared to the theoretical prediction, and the discrepancies suggest that the effect of electrostatic charges is stronger in the larger particles (>3 μm). As filtration progresses, the effect of charges is strongly felt, as the increase in the pressure drop caused by the deposited particles becomes less pronounced with increasing particle charge. In some cases, an increase in the penetration of particles is observed. The relation between particle charge and filtering behavior was not linear: the bed penetration increased, passed through a maximum, and then decreased with increasing particle charge, and the pressure drop behaved accordingly. The measurement of charge distribution between the particles revealed the presence of both positively and negatively charged particles, with the predominance of the former, which resulted in a positive mean charge for the aerosol. This distribution was affected by the level of charging and seems to be responsible for the nonlinear behavior of the filter.