Charge Velocity Research Articles

An experiment to measure electromagnetic memory

Abstract We describe an experiment to measure the electromagnetic analog of gravitational wave memory, the so-called electromagnetic (EM) memory. Whereas gravitational wave memory is a residual displacement of test masses, EM memory is a residual velocity (i.e. kick) of test charges. The source of gravitational wave memory is energy that is not confined to any bounded spatial region: in the case of binary black hole mergers the emitted energy of gravitational radiation as well as the recoil energy of the final black hole. Similarly, EM memory requires a source whose charges are not confined to any bounded spatial region. While particle beams can provide unbounded charges, their currents are too small to be practical for such an experiment. Instead we propose a short microwave pulse applied to the center of a long dipole antenna. In this way the measurement of the kick can be done quickly enough that the finite size of the antenna does not come into play and it acts for our purposes the same as if it were an infinite antenna.

Diagnostic study on laser-produced metal hydride plasmas

The characteristics of laser-produced metal hydride plasmas have been investigated in this work. The charge state and velocity of ions were determined by employing a time-of-flight technique in conjunction with an electrostatic deflection method. The ion velocities were found to be supersonic with values in the range of 104 to 105 m/s. The proportion of hydrogen ions was found to be lower than that of titanium ions. The ion emission behavior was studied by using a Faraday cup. When the total integrated space was taken into account, the ns pulsed laser was capable of producing hydrogen ion currents greater than one hundred mA. In order to understand the plasma generation process, we performed a comparative analysis between laser-generated plasma and arc plasma, and also investigated the effect of laser power density on the composition and velocity of the ions, the ablation properties of metal hydrides, and the maintainability of hydrogen ion emission.

Impact of Velocity of Detonation and Charge per Bank Cubic Meters on Flyrock Throw Prediction Using Support Vector Machine

One of the ambient effects of production blasting is flyrock. To effectively manage flyrock throw distance in mining, there is the necessity to successfully envisage blasting output without sacrificing the hazardous impact of flyrock which may result in fatality and operational shutdown. For flyrock throw distance prediction, velocity of detonation (VOD) and charge per bank cubic meter (CPBCM) are not usually included. This paper focuses on the use of support vector machine (SVM) regression to ascertain the impact of VOD and CPBCM on flyrock throw predictions. The machine learning models were linear support vector machine (LSVM), quadratic Gaussian support vector machine (QGSVM), fine Gaussian support vector machine (FGSVM), medium Gaussian support vector machine (MGSVM), and cubic Gaussian support vector machine (CGSVM). The outcome indicates that FGSVM was the most sensitive with a 4% improvement when VOD and CPBCM were included. As a result, the LSVM model provides a suitable AI competitive alternative tool for flyrock throw prediction in mining operations by incorporating VOD and CPBCM.

Role of electromagnetic energy and momentum in the Aharonov–Bohm effect

We analyse the physical meaning of the Aharonov–Bohm (AB) phase based on its representation through electromagnetic (EM) potentials as a sum of four components, which, in addition to the known electric and magnetic phase components, contains two more terms recently disclosed by our team in the analysis of quantum phase effects for dipoles and charges, and which we named the complementary electric AB phase and the complementary magnetic AB phase. Using the complete expression for the AB phase, we reveal that the phase component, explicitly depending on time, is determined by the interactional electric energy, while the phase component, explicitly depending on the velocity of charge, is determined by the interactional EM momentum for an isolated system ‘source of EM field and charge’. These findings shed new light on the origin of the AB phase and, in particular, allow us to generalize the de Broglie relationship and the Heisenberg uncertainty relations for a charged particle in an EM field.

New insights into diffusion–collection modeling of radiation-induced charge in semiconductor devices

Charge diffusion from an ion track and its collection by a biased contact in a semiconductor domain is modeled and analyzed within the framework of the so-called diffusion–collection approach. We successively examine the case of charge diffusion from a point source and from a linear distribution, introducing and discussing the concept of collection velocity at the point where the collection current is evaluated. Analytical formulations of the collected charge, collection current, and collection velocity are developed. Implications for the calculation of the soft error rate in complementary metal-oxide-semiconductor circuits exposed to ionizing particles are derived. Finally, our model provides new insights into the correct definition of the charge collection velocity in collection–diffusion models.

Bohm sheath criterion and dust charging for active magnetized plasma in the presence of q-nonextensive electron distribution

We have investigated the Bohm sheath criterion and evolution of dust charge at the sheath edge for the collisional active magnetized plasma in the presence of q-nonextensive electron distribution. The set of governing equations has been numerically solved for given initial conditions, whereas the dust charging equation has been solved using the –Raphson method. The Bohm sheath condition for active plasma has been extended using the Sagdeev potential approach, and it has been found that gas pressure, obliqueness of the magnetic field, source and sink terms, and choice of electron distribution affect the Bohm velocity, sheath thickness, floating potential, and evolution of dust charge. As the magnetic field, gas pressure, and nonextensive parameter q increase, the Bohm velocity is found to be decreasing (from supersonic to subsonic), and its explicit effect can be seen on the dust charging process. The magnitude of the E × B drift velocity of ions at the sheath edge determines the Bohm velocity, floating potential, and dust screening length as well. Furthermore, we have presented the comparison of the obtained results for two different cases: (i) unmagnetized and magnetized cases and (ii) active and quiescent plasmas.

Organic phase change materials melting with electrohydrodynamics (EHD): Numerical simulation and experimental validation

Electrohydrodynamics (EHD), as an active heat transfer enhancement technique, would dynamically manipulate the performance of latent heat thermal storage (LHTS) system. In this paper, the melting characteristics of octadecane with EHD were simultaneously investigated by numerical simulation and experiments. A numerical model based on the finite volume method was developed to solve the Poisson-Nernst-Planck equation, Navier–Stokes equation, and energy equation. The solid-liquid interface position, charge density distribution, velocity field, and liquid fraction were reported. The accuracy of the numerical model was evaluated by the experimental results. For the case of melting without EHD, the numerical results agree well with the experimental results. The relative error between the simulation and experiment is less than 20.0% for the case of melting with EHD. The melting time would be significantly saved with the increasing applied voltage magnitude and inner electrode temperature. The melting time with EHD would be reduced by 13.6 times compared to the natural melting case. The flow in the liquid phase is chaotic and the Coulomb force is dominant than the dielectric force and the buoyancy. In addition, the influence of electrode arrangement on the melting behavior is studied. The melting can be decreased by 1.26 to 1.84 times by adopting four electrodes compared to melting under the configuration of a single electrode with the same cross-section. The proposed numerical model provides a reference for designing and predicting LHTS performance with EHD.

An adaptive frequency regulation strategy with high renewable energy participating level for isolated microgrid

To improve the renewable energy sources (RES) utilization of isolated microgrids (IMG) in frequency regulation process, an adaptive frequency regulation strategy with high renewable energy participating level is proposed in this paper: 1) an adaptive droop control method is conceived for primary frequency regulation, in which the designed droop coefficients are adjustable with the real-time wind velocity and state of charge (SoC) of energy storage units (ESUs); as the most important contribution, 2) a general flexible model predictive control (FMPC) framework with adaptive cost function and constraints is developed for secondary frequency regulation. For 2), i) the weight coefficients of the cost function can be adaptively adjusted according to frequency deviation through a pre-designed intelligent function, in which the specification of determining the key parameters is involved; ii) the designed constraints' boundaries can dynamically shift with wind velocity and ESU's SoC; iii) the negative impact of model's uncertainties can also be mitigated by implementing the proposed FMPC. Finally, the effectiveness of the proposal is verified by the comprehensive simulation and experimental study, and the results show that the proposal can significantly improve RES's utilization level while guaranteeing frequency regulation performance and operation safety in IMG.

On Two Non-Ergodic Reversible Cellular Automata, One Classical, the Other Quantum.

We propose and discuss two variants of kinetic particle models-cellular automata in 1 + 1 dimensions-that have some appeal due to their simplicity and intriguing properties, which could warrant further research and applications. The first model is a deterministic and reversible automaton describing two species of quasiparticles: stable massless matter particles moving with velocity ±1 and unstable standing (zero velocity) field particles. We discuss two distinct continuity equations for three conserved charges of the model. While the first two charges and the corresponding currents have support of three lattice sites and represent a lattice analogue of the conserved energy-momentum tensor, we find an additional conserved charge and current with support of nine sites, implying non-ergodic behaviour and potentially signalling integrability of the model with a highly nested R-matrix structure. The second model represents a quantum (or stochastic) deformation of a recently introduced and studied charged hardpoint lattice gas, where particles of different binary charge (±1) and binary velocity (±1) can nontrivially mix upon elastic collisional scattering. We show that while the unitary evolution rule of this model does not satisfy the full Yang-Baxter equation, it still satisfies an intriguing related identity which gives birth to an infinite set of local conserved operators, the so-called glider operators.

Maximum fragment velocity of hollow charges with different aspect ratios

Fragment velocity is an important indicator of warhead damage power. The maximum fragment velocity varies with the charge aspect ratios. Existing formulae for the maximum velocity have limits and do not apply to hollow charges. In this work, numerical models based on experimental results were conducted on hollow charges with various aspect ratios. Under the different hollow diameters, the changing rules of the maximum fragment velocity along with the aspect ratios are consistent with each other. The differences between the driving behaviors under different detonations were also discovered. A new formula applicable to hollow charges for the maximum fragment velocity under end detonations was established. Furthermore, a formula for the maximum fragment velocity under the central line or hollow surface detonations was obtained for the first time. The accuracies of the established formulae were verified against the experiments. This study can provide valuable references for the optimal design and damage assessment of ammunition, and also for the design of protection structures.

Electromagnetic induction: How the “flux rule” has superseded Maxwell's general law

As documented by textbooks, the teaching of electromagnetic induction in university and high school courses is primarily based on what Feynman labeled as the “flux rule,” downgrading it from the status of physical law. However, Maxwell derived a “general law of electromagnetic induction” in which the vector potential plays a fundamental role. A modern reformulation of Maxwell's law can be easily obtained by defining the induced electromotive force as ∮l(E→+v→c×B→)·dl→, where v→c is the velocity of the positive charges which, by convention, are the current carriers. Maxwell did not possess a model for the electric current. Therefore, in his law, he took v→c to be the velocity of the circuit element containing the charges. This paper aims to show that the modern reformulation of Maxwell's law governs electromagnetic induction, and the “flux rule” is not a physical law but only a calculation shortcut that does not always yield the correct predictions. This paper also tries to understand why Maxwell's law has been ignored, and how the “flux rule” has taken root. Finally, a section is dedicated to teaching this modern reformulation of Maxwell's law in high schools and elementary physics courses.

Impact of aspect ratio on fragment velocity distribution for hollow charges

Hollow charges play essential roles in the warhead design, detonation wave control, and lethality tuning. The superficial structure difference with solid charges prevents the direct application of Gurney's formula to determine fragment velocity. Tools are demanded in the design of hollow charges. Apart from checking the actual detonation driving behavior, a variety of different methods were used to solve this problem. And when developing these methods, 2 times the aspect ratio is often believed to be sufficient to treat detonation driving as a plane strain model (removing the influence of rarefaction waves). This study, however, reaches different conclusions about these aspects. Based on the discovered linear velocity distribution of the detonation products, a new formula was developed for the theoretical maximum fragment velocity of hollow charges. The formula applies to the non-plane strain state caused by end-face initiations. Furthermore, new fragment velocity distribution formulae based on results of a broad range of aspect ratios have been developed, the first time for the central line or hollow surface initiation. Based on numerical modeling and experiments, the entire formula system was verified to be precise and more applicable. This study can provide important references for the design of new structure warheads and lethality tuning warheads, as well as for damage effectiveness evaluation.

Design and Assessment of a Novel Biconical Human-Sized Alternating Magnetic Field Coil for MNP Hyperthermia Treatment of Deep-Seated Cancer.

Magnetic nanoparticle (MNP) hyperthermia therapy is a treatment technique that can be used alone or as an adjunct to radiation and/or chemotherapies for killing cancer cells. During treatment, MNPs absorb a part of electromagnetic field (EMF) energy and generate localized heat when subjected to an alternating magnetic field (AMF). The MNP-absorbed EMF energy, which is characterized by a specific absorption rate (SAR), is directly proportional to AMF frequency and the magnitude of transmitting currents in the coil. Furthermore, the AMF penetrates inside tissue and induces eddy currents in electrically conducting tissues, which are proportional to the electric field (J = σE). The eddy currents produce Joule heating (<J·E> = 0.5·σ·E2) in the normal tissue, the rate of energy transfer to the charge carriers from the applied electric fields. This Joule heating contains only the electric field because the magnetic field is always perpendicular to the velocity of the conduction charges, i.e., it does not produce work on moving charge. Like the SAR due to MNP, the electric field produced by the AMF coil is directly proportional to AMF frequency and the magnitude of transmitting currents in the coil. As a result, the Joule heating is directly proportional to the square of the frequency and transmitter current magnitude. Due to the fast decay of magnetic fields from an AMF coil over distance, MNP hyperthermia treatment of deep-seated tumors requires high-magnitude transmitting currents in the coil for clinically achievable MNP distributions in the tumor. This inevitably produces significant Joule heating in the normal tissue and becomes more complicated for a standard MNP hyperthermia approach for deep-seated tumors, such as pancreatic, prostate, liver, lung, ovarian, kidney, and colorectal cancers. This paper presents a novel human-sized AMF coil and MNP hyperthermia system design for safely and effectively treating deep-seated cancers. The proposed design utilizes the spatial distribution of electric and magnetic fields of circular coils. Namely, it first minimizes the SAR due to eddy currents in the normal tissue by moving the conductors away from the tissue (i.e., increasing coils' radii), and second, it increases the magnetic field at the targeted area (z = 0) due to elevated coils (|z| > 0) by increasing the radius of the elevated coils (|z| > 0). This approach is a promising alternative aimed at overcoming the limitation of standard MNP hyperthermia for deep-seated cancers by taking advantage of the transmitter coil's electric and magnetic field distributions in the human body for maximizing AMF in tumor regions and avoiding damage to normal tissue. The human-sized coil's AMF, MNP activation, and eddy current distribution characteristics are investigated for safe and effective treatment of deep-seated tumors using numerical models. Namely, computational results such as AMF, Joule heating SAR, and temperature distributions are presented for a full-body, 3D human model. The SAR and temperature distributions clearly show that the proposed human-sized AMF coil can provide clinically relevant AMF to the region occupied by deep-seated cancers for the application of MNP hyperthermia therapy while causing less Joule heating in the normal tissues than commonly used AMF techniques.

Changes in the Mechanical Behavior of Electrically Aged Lithium-Ion Pouch Cells: In-Plane and Out-of-Plane Indentation Loads with Varying Testing Velocity and State of Charge

The knowledge about the influence of electrical aging on the behavior of lithium-ion cells under mechanical loads is of high importance to ensure a safe use of batteries over the lifetime in electric vehicles. In order to describe the mechanical behavior in relation to electrical aging, fresh and electrically aged NCM pouch cells were investigated under different mechanical crash loads. For the first time, the aged cells’ behavior under quasistatic lateral loading was taken into account. Aged cells showed lower maximum forces compared to the fresh cells. The reason of the changed mechanical cell behavior was explained with the different buckling behavior of fresh and aged cells by experimental images. Furthermore, quasistatic and dynamic crash tests in cell’s thickness direction were performed at varying state of charge (SOC) and compared to the results of a previously published study. Independently of the testing velocity, the electrically aged cells failed at increased deformation values. This observation was justified by an increased cell thickness due to an additional softer layer, formed on the aged graphite particle surface, which was observed by the means of scanning electron microscopy. Furthermore, the aged cells showed lower failure forces of up to −11% under quasistatic and dynamic loads at 0% SOC. It was also illustrated that electrical aging causes a deeper voltage drop after cell failure, which suggests a higher energy release after the internal short circuit. The investigations show that electrical aging has a significant influence on the mechanical properties of lithium-ion cells and must be taken into account in the safety assessment.

Charge–velocity correlation transport equations in gas–solid flow with triboelectric effects

This paper is dedicated to the development of particle charge and velocity second-order moment transport equations for monodisperse particles in gas flow with a tribocharging effect. The full transport equations for the particle charge–velocity covariance and the charge variance are derived in the framework of the kinetic theory of granular flow assuming that the electrostatic interaction does not modify the collision dynamics. The collision integrals are solved without presuming the form of the electric part for the particle probability density function. The full second-order transport equation model is tested in a one-dimensional periodic domain. The results show that this model is able to capture more important physical mechanisms that are neglected by simple algebraic models proposed in the past. An in-depth analysis of the transport equations is also performed. This study reveals that, for sufficiently small covariance characteristic destruction time scales, the transient and third-order moments terms can be safely neglected. In addition, two different reduced-order models are proposed: a more general algebraic model that takes into account the variance effect and a semi-algebraic model that only resolves a transport equation for the charge variance coupled with an algebraic model for the covariance. The former could, however, lead to non-physical predictions in many cases, while the latter can be a suitable alternative only for a sufficiently small interparticle collision time. Finally, a simple chart based on test case simulations is proposed to show under which conditions a semi-algebraic model could be considered as a suitable alternative.

Влияние эмульсионных взрывчатых веществ на скорость детонации скважинного заряда

The input control of explosive materials and the measurement of the detonation rate of the charge are important in the production of explosive work. The detonation rate of the explosive charge, as one of its most important characteristics affecting the quality of the explosion, depends on many factors, the main of which are: the quality of preparation of explosives and their components. Incorrectly selected parameters of drilling and blasting operations and poor quality of preparation of explosives lead to a decrease in the detonation rate up to detonation failures. In turn, detonation failures lead to an increase in material costs and an increase in the risk of negative events related to safety when handling explosive materials. The correct approach to preliminary quality control with the use of appropriate measurements will improve the efficiency and safety of preparing the rock mass for excavation by drilling and blasting. The article presents a technique for measuring the detonation velocity of a borehole charge with the corresponding results and conclusions, allowing timely measures to be taken to maintain the detonation velocity of explosives at the required level.

Effect of Temperature on Current Pulse Characteristics of Negative Corona Discharge Based on Numerical Model

Temperature is an important factor affecting the dynamic processes of corona discharge, since the ionization, attachment, and mobility of charged particles are directly related to temperature. Most existing research has investigated the temperature effect on corona discharge through experimental works. However, they are hard to acquire the corona discharge microphysical processes, which are related to the formation of the current pulse and electromagnetic (EM) wave signals. This article proposes a numerical model with temperature-related transport parameters to study the temperature influence on microphysical processes and current pulses for negative corona. By comparing microphysical quantities such as the effective ionization coefficient, density, and velocity of space charges, the effect of temperature on the current pulse parameters including the rise and fall times, amplitude, and pulsewidth is systematically explained. It shows that as the temperature rises, the current pulse amplitude increases, while the other three parameters decrease. The rise time is dependent on the effective ionization coefficient. The fall time is affected by the velocities of negative and positive ions. The experimental results indicate the simulated current pulses are consistent with the measured ones, proving the effectiveness of the proposed numerical model with temperature variation.

Surface charging and electrophoretic behavior of conductive polymer micro-droplets in conductive polymer liquid solutions.

This study investigates the surface charging and electrophoretic motion of polyethylene glycol-rich (PEG-rich) micro-droplets in dextran-rich solutions or dextran-rich micro-droplets in PEG-rich solutions. The electrophoretic velocities of the droplets were measured in a centimeter-sized chamber under an optical microscope. It was found that the direction of electrophoretic motion of both the PEG-rich droplets and dextran-rich droplets is opposite to the applied electric field, meaning that both the PEG-rich droplets and dextran-rich droplets are negatively charged. The electrophoretic velocity is independent of droplet size but proportional to the electric field strength. Increasing the NaCl concentration reduces the electrophoretic velocity of PEG-rich droplets and increases it for dextran-rich droplets, suggesting different surface charge changes due to ion affinity. The charge densities and velocities are affected by the PEG and dextran mass fractions. Physical models for droplet surface charging under different conditions were proposed to explain the experimental results.

The influence of DC voltage on the conductivity of chloroprene rubber-carbon black composites for flexible resistive heating elements.

In order to acquire a flexible resistive heating element in the temperature range for human body heating, the influence of DC voltage on chloroprene rubber (CR) and carbon black (CB) composites has been investigated. Three conduction mechanisms have been found to occur in the range from 0.5 V to 10 V - charge velocity increase due to the increase of the electric field, matrix thermal expansion that results in decreased tunnelling currents and new electroconductive channel formation at voltages above 7.5 V, where the temperature exceeds the matrix's softening point. As opposed to external heating, during resistive heating, the composite exhibits a negative temperature coefficient of resistivity up to an applied voltage of 5 V. The intrinsic electro-chemical matrix properties play an important role in the overall resistivity of the composite. The material shows cyclical stability when repeatedly applying a voltage of 5 V and can be used as a human body heating element.

Experimental and numerical investigation of blast loads induced by moving charge explosion

With the development of high-speed weapons, moving charge explosions frequently occur in industry and military activities, which will lead to significant damage to structures. In order to investigate the blast loads induced by moving charge explosion, explosion experiments are carried out. The pressure curves and blast load parameters are analyzed. Results indicate that the blast load distribution is directional in moving charge explosion, and the blast load parameters are influenced by distance and direction. Numerical simulation investigation is conducted to further study the effect of charge shape and velocity on blast loads induced by moving charge explosion. The numerical model is developed and verified with experiment data, which indicates that the numerical method is sufficiently accurate for moving charge explosion investigation. The numerical study characterizes the influence of charge shape and charge velocity on blast loads in different directions. The shape factors of cylindrical charge and the velocity factors of 580 m/s, 700 m/s, 900 m/s and 1200 m/s in moving charge explosion are analyzed. The results indicate that the charge shape effect must be considered in the near-field and the charge velocity effect must be considered in different directions, especially in directions with angles less than 90°. This research will contribute to combatant power evaluation, structural engineering and structural design.