Constant Electric Field Research Articles

Internal dynamics of a polaron uniformly moving along a molecular chain in a constant electric field

This paper presents a detailed study of the uniform motion of a Holstein polaron as it moves along a chain in a constant electric field. The calculations showed that, depending on the parameters of the system, the duration of the uniform motion of the polaron along the chain can reach tens and hundreds of Bloch periods for a given value of the electric field intensity. It is shown that in the process of the uniform motion, the macro-part of the polaron moves at a constant velocity, retaining its shape. At the same time, the low-density components of the polaron, which arise immediately when a constant electric field is instantaneously switched on, have their own internal dynamics and demonstrate characteristic elements of the Bloch oscillations, such as the period of Bloch oscillations and the maximum Bloch amplitude. It is shown that not only the velocity and duration of the uniform motion of the polaron, but also the characteristics of the low-density components of the polaron depend on the value of the electric field intensity.

Effect of doping on domain suppression in the presence of hot electrons in semiconducting achiral carbon nanotubes

Effect of doping semiconducting achiral carbon nanotubes on domain suppression prerequisite for potential generation of terahertz radiations in the presence of hot electrons has been theoretically considered. This was done by solving the semiclassical Boltzmann's transport equation in the presence of hot electrons source to derive the current density as a function of constant electric field and chemical potential of semiconducting achiral carbon nanotubes (CNTs). Plots of normalized current density versus electric field strength for semiconducting achiral CNTs as the chemical potential (μ) representing the degree of doping increases from 1.4 eV to 2.0 eV (i.e. heavily doped CNT) revealed an increase in positive differential conductivity (PDC) that results in enhancement of domain suppression prerequisite for generation of terahertz radiations. Also, it has been observed that PDC which is associated with domain suppression increases as the relative thickness and carrier temperature of semiconducting CNTs increase. Therefore, the study predicts heavily doped larger radius semiconducting achiral CNT at a higher carrier temperature as a better candidate for generation of terahertz radiations whose applications are relevant in current-day technology, industry, and research.

Gravitational Landau levels and the chiral anomaly

A popular physical picture of the mechanism behind the four-dimensional chiral anomaly is provided by the massless Dirac equation in the presence of constant electric and magnetic background fields. The magnetic field creates highly degenerate Landau levels, the lowest of which is gapless. Any parallel component of the electric field drives a spectral flow in the gapless mode that causes particles to emerge from, or disappear into, the Dirac sea. Seeking a similar picture for the gravitational contribution to the chiral anomaly, we consider the massless Dirac equation in a background spacetime that creates gravitational Landau levels. We find that in this case the resulting spectral flow, with its explicit particle production, accounts for only a small part of the anomalous creation of chiral charge. The balance is provided by the vacuum expectation charge arising from the spectral asymmetry.

An Extended Kolmogorov-Avrami-Ishibashi (EKAI) Model to Simulate Dynamic Characteristics of Polycrystalline-Ferroelectric-Gate Field-Effect Transistors.

A physics-based model on polarization switching in ferroelectric polycrystalline films is proposed. The calculation results by the model agree well with experimental results regarding dynamic operations of ferroelectric-gate field-effect transistors (FeFETs). In the model, an angle θ for each grain in the ferroelectric polycrystal is defined, where θ is the angle between the spontaneous polarization and the film normal direction. Under a constant electric field for a single-crystal film with θ = 0, phenomena regarding polarization domain nucleation and wall propagation are well described by the Kolmogorov-Avrami-Ishibashi theory. Since the electric fields are time-dependent in FeFET operations and the θ values are distributed in the polycrystalline film, the model in this paper forms an extended Kolmogorov-Avrami-Ishibashi (EKAI) model. Under a low electric field, the nucleation and domain propagation proceed according to thermally activated processes, meaning that switching the time scale of a grain with the angle θ is proportional to an exponential form as exp(const./Ezcosθ) [Ez: the film-normal electric field]. Wide θ distribution makes the time response quite broad even on the logarithmic scale, which relates well with the broad switching time experimentally shown by FeFETs. The EKAI model is physics based and need not assume non-physical distribution functions in it.

QCD phase diagram and equation of state in background electric fields

The phase diagram and the equation of state of quantum chromodynamics (QCD) is investigated in the presence of weak background electric fields by means of continuum extrapolated lattice simulations. The complex action problem at nonzero electric field is circumvented by a novel Taylor expansion, enabling the determination of the linear response of the thermal QCD medium to constant electric fields—in contrast to simulations at imaginary electric fields, which, as we demonstrate, involve an infrared singularity. Besides the electric susceptibility of QCD matter, we determine the dependence of the Polyakov loop on the field strength to leading order. Our results indicate a plasma-type behavior with a negative susceptibility at all temperatures, as well as an increase in the transition temperature as the electric field grows. Published by the American Physical Society 2024

Coalescence-Induced Jumping of Nanodroplets in a Perpendicular Electric Field: A Molecular Dynamics Study.

Coalescence-induced jumping has promised a substantial reduction in the droplet detachment size and consequently shows great potential for heat-transfer enhancement in dropwise condensation. In this work, using molecular dynamics simulations, the evolution dynamics of the liquid bridge and the jumping velocity during coalescence-induced nanodroplet jumping under a perpendicular electric field are studied for the first time to further promote jumping. It is found that using a constant electric field, the jumping performance at the small intensity is weakened owing to the continuously decreased interfacial tension. There is a critical intensity above which the electric field can considerably enhance the stretching effect with a stronger liquid-bridge impact and, hence, improve the jumping performance. For canceling the inhibition effect of the interfacial tension under the condition of the weak electric field, a square-pulsed electric field with a paused electrical effect at the expansion stage of the liquid bridge is proposed and presents an efficient nanodroplet jumping even using the weak electric field.

Influence of a Constant Electric Field on the Structure and Properties of Chlorosulfonated Polyethylene Films during Formation from Solution

Influence of a Constant Electric Field on the Structure and Properties of Chlorosulfonated Polyethylene Films during Formation from Solution

소규모 폐쇄 환경에서 스몰 셀을 연계한 이동통신 전파환경 개선방안

This paper proposes a plan to improve the reception radio environment of the mobile terminal and maintain a constant reception electric field by using small cells in a small closed environment. In order to configure an efficient communication infrastructure for small cells, both ends of wireless transmission and reception of an Ethernet-based wireless video recording system are connected using an L2 switch. The small cell connected to the receiving side L2 switch shares the wireless network section of the wireless video recording system and connects to the transmitting side L2 switch. After that, when it is normally linked to FMS, a management system for small cells, through the Internet network, the output of small cells is checked. In order to verify the results, a proposed network is formed on the elevator inside the building with a poor radio wave environment, and the radio wave environment is measured before and after the small cell application in the section where the elevator operates. As a result, the main parameters of the radio wave environment in all sections of the elevator are improved, as well as a constant receiving electric field strength within the moving elevator.

Effect of a constant electric field on the electromagnetic spectrum structure of eucalyptus oil

Effect of a constant electric field on the electromagnetic spectrum structure of eucalyptus oil

Low Concentrations of Gold Nanoparticles as Electric Charge Carriers in Piezoelectric Cement-Based Materials.

Piezoelectric cement-based composites could serve to monitor the strain state of structural elements or act as self-powered materials in structural health monitoring (SHM) applications. The incorporation of piezoelectric materials as an active phase within cement matrices has presented a highly attractive avenue until today. However, their application is challenged by the low electrical conductivity of the hydrated cement matrix. Gold nanoparticles (Au NPs) possess substantial potential for elevating the free electrical charge within the matrix, increasing its electrical conductivity between the Au NPs and the cement matrix, thereby enhancing the piezoelectric response of the composite. In this sense, the objective of this study is to investigate the effects of incorporating low concentrations of gold nanoparticles (Au NPs) (442 and 658 ppm) on the electrical and piezoelectric properties of cement-based composites. Additionally, this study considers the effects of such properties when the material is cured under a constant electric field. Electrical impedance spectroscopy was used to evaluate the polarization resistance and piezoresistive properties of the material. Additionally, open-circuit potential measurements were taken alongside the application of mechanical loads to assess the piezoelectric activity of the composites. The findings revealed a notable decrease in the composite's total electrical resistance, reaching a value of 1.5 ± 0.2 kΩ, almost four times lower than the reference specimens. In the realm of piezoelectricity, the piezoelectric voltage parameter g33 exhibited a remarkable advancement, improving by a factor of 57 when compared to reference specimens. This significant enhancement can be attributed to both the concentration of Au NPs and the electrical curing process. In summary, the outcomes of this study underscore the feasibility of creating a highly electrically conductive cement-based matrix, using low concentrations of gold nanoparticles as electric charge carries, and indicate the possible piezoelectric behavior of the studied compposite.

On spectral and scattering theory for one-body quantum systems in crossed constant electric and magnetic fields

In this paper, we study the spectral and scattering theory on the Hamiltonians which govern one-body quantum systems in crossed constant electric and magnetic fields. As one of the spectral features of the Hamiltonians, we show the absence of bound states of theirs under some appropriate conditions on the potentials. Moreover, by using the limiting absorption principle for the Hamiltonians, we give a simplified proof of the asymptotic completeness in short-range scattering.

Optical gain and entanglement through dielectric confinement and electric field in InP quantum dots.

Quantum dots are widely recognized for their advantageous light-emitting properties. Their excitonic fine structure along with the high quantum yields offers a wide range of possibilities for technological applications. However, especially for the case of colloidal QDs, there are still characteristics and properties which are not adequately controlled and downgrade their performance for applications which go far beyond the simple light emission. Such a challenging task is the ability to manipulate the energetic ordering of exciton and biexciton emission and subsequently control phenomena such as Auger recombination, optical gain and photon entanglement. In the present work we attempt to engineer this ordering for the case of InP QDs embedded in polymer matrix, by means of their size, the dielectric confinement and external electric fields. We employ well tested, state of the art theoretical methods, in order to explore the conditions under which the exciton-biexciton configuration creates the desired conditions either for optical gain or photon entanglement. Indeed, this appears to be feasible for QDs with small diameters (1 nm, 1.5 nm) embedded in a host material with high dielectric constant and additional external electric fields. These findings offer a new design principle which might be complementary to the well-established type II core-shell QDs approach for achieving electron-hole separation.

Optimizing the formation of aerobic granular sludge and enhanced pollutant removal efficiency in a constant current variable voltage electric field

Aerobic granular sludge (AGS) disintegration occurs during long-term operation, decreasing particle settling performance and deteriorating the pollutant removal effect. Therefore, this experiment proposes an electric field synergistic AGS construction to improve the strength of particles and the efficiency of nitrogen and phosphorus removal. The study revealed that under the influence of an electric field, iron ions dissolved from the iron electrode and phosphate formed mineral nuclei inside the particles, which effectively increased the average size of the particles and increased the protein content of extracellular polymeric substances (EPS). The experimental results demonstrated that including Fe–C electrodes in the electric field group increased the TN removal rate to 86.65%, surpassing the rates observed in the blank without an electric field and C–C electrode electric field groups by factors of 1.13 and 1.11, respectively. Under the electric field, AGS enriched some functional microorganisms for denitrogenation, thus improving total nitrogen removal efficiency. Furthermore, the phosphorus removal efficiency in the electric field group featuring Fe–C electrodes exhibited a notable enhancement, reaching 90.16%. This improvement was 1.71 and 1.62 times that of blank without an electric field and C–C electrode electric field groups, respectively. The phosphorus removal efficacy of electrode-released iron is distinct from that of exogenous ferrous sulfate, with the former demonstrating superior activity and pronounced phosphorus removal capabilities. Therefore, this study comprehensively revealed AGS construction mechanism and pollutant removal efficacy under the electric field's synergistic effect.

СПОСОБ ОБЕЗЗАРАЖИВАНИЯ ВОЗДУШНОЙ СРЕДЫ В ЦЕХАХ ПРОИЗВОДСТВА ПОЛУФАБРИКАТОВ ИЗ МЯСА ПТИЦЫ

Devices for air decontamination usage in departments for poultry meat cutting up and ready-to-cook products making gives the possibility to reduce the department air environment and carcasses surfaces microbial insemination. These devices doesn’t influence on poultry meat sensory and physic-chemical properties but increases shelf-life by one day. This device works at the base of repeated exposure of constant electrical fields with alternating polarity on microorganisms. One device is counted on 60 m3 of air in the room.

Computer homogenization of porous piezoceramics of different ferrohardness with random porous structure and inhomogeneous polarization field

The article is concerned with the homogenization problems, in which the effective moduli of porous piezoceramic composites are determined taking into account the inhomogeneity of the polarization field. The homogenization problems are solved by the finite element method in the framework of the theory of effective moduli and the Hill energy principle using the ANSYS package. To this end, in static problems of electroelasticity, the displacements and electric potential, which are linear in spatial variables, are specified on the boundary of a representative volume to provide constant stress and electric induction fields for a homogeneous reference medium. After solving a set of boundary value problems under different boundary conditions and determining the volume-averaged stress components and the electric induction vector, a complete set of effective moduli for the piezoelectric composite is calculated. A representative volume of the piezocomposite is created in the form of a regular finite element mesh consisting of cubic elements. Pores in the representative volume are assumed to be filled with a piezoelectric material with extremely small moduli. Finite elements with pore properties are selected according to a simple random algorithm. The inhomogeneous polarization field is found by solving an electrostatic problem, in which the polarization process in the representative volume is modeled based on a simplified linear formulation. The local coordinate systems for individual finite elements of the composite matrix are specified by the directions of the polarization vectors. In the following, when solving the problems of electroelasticity, these local coordinate systems associated with the elements of the piezoelectric matrix allow recalculating the material properties according to the formulas of transformation of the tensor components as the coordinate systems rotate. In addition, consideration is given to different models describing the change in the moduli of the material from an unpolarized state to a polarized one as a function of the polarization vector. Computational experiments were carried out for three types of piezoceramics: soft ferroelectric piezoceramics PZT-5H, piezoceramics PZT-4 of medium ferrohardness, and piezoceramics PZT-8 with higher degree of ferrohardness. The dependences of the effective moduli on porosity are compared for different laws of polarization inhomogeneity and different kinds of piezoceramic material of the composite matrix.

The effect of frequency (64-498MHz) on specific absorption rate adjacent to metallic orthopedic screws in MRI: A numerical simulation study.

The imaging of patients with implanted electrically-conductive devices via magnetic resonance imaging at ultra-high fields is hampered by uncertainties relating to the potential for inducing tissue heating adjacent to the implant due to coupling of energy from the incident electromagnetic field into the implant. Existing data in the peer-reviewed literature of comparisons across field strengths of tissue heating and its surrogate, the specific absorption rate (SAR), is scarce and contradictory, leading to further doubts pertaining to the safety of imaging patients with such devices. The radiofrequency-induced SAR adjacent to orthopedic screws of varying length and at frequencies of 64 to 498MHz was investigated via full-wave electromagnetic simulations, to provide an accurate comparison of SAR across MRI field strengths. Dipole antennas were used for RF transmission to achieve a uniform electric field tangential to the screws located 120mm above the antenna midpoints, embedded in a bone-mimicking material. The input power to the antennas was constrained to achieve the following targets without the screw present: (i) E=100V/m, (ii) B1 + =2 μT, and (iii) global-average-SAR=3.2W/kg. Simulations were performed with a spatial resolution of 0.2mm in the volume surrounding the screws, resulting in 76-137 MCells, noting the maximum 1g-averaged SAR value in each case. Simulations were repeated at 128 and 297MHz for screws embedded in muscle tissue. The peak SAR, occurring at the resonant screw length, substantially increased as the frequency decreased when the input power to the dipole antenna was constrained to achieve constant electric field in background tissue at the screws' locations. A similar pattern was observed when constraining input power to achieve constant B1 + and global-average-SAR. The dielectric properties of the tissue in which the screws were embedded dominated the SAR comparisons between 297 and 128MHz. The study design allowed for a direct comparison to be performed of SAR across frequencies and implant lengths without the confounding effect of variable incident electric field. Lower frequencies produced substantially larger SAR values for implants approaching the resonant length for the worst-case uniform incident electric field along the screws' length. The data may inform risk-benefit assessments for imaging patients with orthopedic implants at the new clinical field strength of 7Tesla.

Fractional Laplacian Spinning Particle in External Electromagnetic Field

We construct a fractional Laplacian spinning particle model in an external electromagnetic field that generalizes a standard relativistic spinning particle model without anti-commuting spin variables. The one-dimensional fractional Laplacian in world-line variable λ governs the kinetic energy that is non-local in λ. The interaction between the particle’s charge and the electromagnetic four-potential is non-local in λ, while the interaction between the particle’s spin tensor and the electromagnetic field is standard. By applying the variational principle, we obtain the equations of motion for particle coordinates. We solve analytically the equations of motion in two particular cases: the constant electric and magnetic field. For more complex field configurations, the equations are, in general, non-local and non-linear. By making the assumption of a much weaker interaction term between the charge and four-potential compared with the interaction between spinning degrees of freedom and the electromagnetic field, we obtain approximate analytical solutions in the case of a quadratic electromagnetic potential.

Properties of Polymer Films Based on Cellulose Diacetate with Intercalated Zn{(NH2)2Co}2Br2

The work is devoted to the fabrication and study of electret material based on cellulose diacetate polymer film with an intercalated active component, polar macromolecules Zn{(NH2)2CO}2Br2. The introduction of macromolecules into the film was carried out during its formation from solutions of various concentrations of cellulose diacetate and Zn{(NH2)2CO}2Br2 in tetrahydrofuran with ethyl alcohol under the action of a constant electric field of 2–4 kV cm–1. The temperature curves of the dielectric constant ε, the dielectric loss tangent tan δ, as well as the thermally stimulated depolarization currents j of the resulting films were determined. It was established that modification leads to the appearance of additional maxima in the ε(T), tan δ(T), and j(T) curves caused by the active component embedded in the film. Modification of a cellulose diacetate film causes an increase in the value of j and the surface charge density found from the j(T) curve by more than two orders of magnitude. The results obtained indicate the possibility of application of the method under consideration to fabricate electret films.

The nano-pumping process of C20 molecules from carbon nanotube at the different external electric fields and atomic defects: A molecular dynamics approach

Today, carbon nanotubes are involved in many medical types of research, such as biosensors and drug delivery. These nanotubes do not pose a problem for the body regarding toxicity to body cells and triggering the immune system. Nanotubes have also been proven to increase solubility and the possibility of targeted drug delivery. This study used molecular dynamics simulation to examine the nano-pumping process of the C20 molecule in carbon nanotubes at the different electric fields and atomic defects. The process of C20 molecule nano-pumping was examined by examining the changes in kinetic energy, potential energy, entropy, stress, temperature, and internal energy changes. In the following, the stress on the atomic structure was calculated. For this purpose, constant electric fields with the magnitudes of 0.01, 0.02, 0.03, 0.05, and 0.1 V/Å are used for the atomic structure. The results show that the nano-pumping time of the C20 molecule in the carbon nanotubes increases by increasing the electric field magnitude. The results also revealed that the kinetic energy in the structure decreased by increasing the electric fields, and the potential energy increased. As the potential energy increased in the atomic structure, the stability increased. Therefore, it is expected that the C20 molecule nano-pumping time will increase. The following examined the effect of atomic defects in an electric field with a magnitude of 0.01 V/Å. For this purpose, the atomic defects with magnitudes of 1 %, 2 %, 3 %, and 4 % were used for carbon nanotubes. The results revealed that increasing the atomic defects increased the C20 molecule nano-pumping time. Furthermore, the stress on the structure increased by increasing the atomic defects.

Evaluation of the quality and stability of freeze-dried fruits and vegetables pre-treated by pulsed electric fields (PEF)

This study investigates the application of Pulsed Electric Field (PEF) technology to improve the freeze-drying process, the final product quality and the stability of kiwi fruits, red bell peppers, and red beetroots. Freeze-drying is a fundamental drying technology that aims to maintain the natural attributes of food, but it often leads to challenges such as prolonged drying times and quality degradation. To further understand the implications of applying PEF before freeze-drying, the storage stability of the freeze-dried samples was investigated under both illuminated and dark conditions. PEF treatment was carried out at constant electric field strength of E = 1.0 kV/cm, and specific energy input was varied between 0.2 and 20.8 kJ/kg. This study revealed that PEF treatment significantly decreased the freeze-drying time (2-fold) exclusively for bell peppers. PEF treatment substantially improved volume retention and rehydration capacity for both kiwi fruits and bell peppers, indicating enhanced structural integrity. However, applying PEF had an overall adverse impact on the colour stability of the freeze-dried samples (ΔE > 3). The quality decline was mitigated storing the samples in dark conditions. The results of this study suggest that applying PEF before freeze-drying can represent a promising strategy to enhance the quality of freeze-dried products with improved drying kinetics, volume retention, and rehydration capacity. Careful consideration of storage conditions is essential to prevent the deterioration of product quality over time.