Impulse Condition Research Articles

Transient analysis of earthing electrodes considering soil ionization phenomenon under lightning impulse condition

Transient analysis of earthing electrodes considering soil ionization phenomenon under lightning impulse condition

Energy harvesting induced by the vibration of reciprocating-piston compressor subjected to repetitive impulse

In this study, discrete event time-variant parameter of a lumped SISO dynamical system is obtained for a novel energy harvester. The harvester utilizes the resonance vibration of a coupled fluid-mechanic system, which is comprised of a reciprocating-piston, a tunable oscillator and twin electric turbine generators. The system model is simplified by an underdamped spring-mass-damper with tunable parameters subjected to periodic or arbitrary impulse forces. We developed a method that solves general problems underlining non-homogenous ordinary second order differential equation with discrete event time-variant parameters. The method uses the superposition to compile the general solution by segmenting the problem into ODE equations with constant coefficient. Each segment corresponds to a change in system, and it is solved analytically with recursively updated initial conditions. We utilized this method to tune the system’s natural frequency such that the accumulated energy is maximum within desired time range. We obtained the general solution of the displacement response due to varying parameters and input impulse force. We obtained the displacement peaks and their time of occurrence that could help understand the structural design limitation. We showed system displacement responses (constructive and destructive) corresponding to various impulse repetition patterns. We derived the relationship between energy, volume displacement, and volumetric flow rate (or piston velocity) and provided illustrative case studies. One finding shows that for a given impulse condition the accumulative energy exhibits local maximum and minimum within a narrow band of natural frequency range. The simulations showed the feasibility of generating considerable power from electric turbine when the air flow is driven by a resonating piston.

Fractional non-autonomous evolution equations with integral impulse condition in Fréchet spaces

Fractional non-autonomous evolution equations with integral impulse condition in Fréchet spaces

NON-AUTONOMOUS FRACTIONAL EVOLUTION EQUATIONS WITH NON-INSTANTANEOUS IMPULSE CONDITIONS OF ORDER (1,2): A CAUCHY PROBLEM

The non-instantaneous condition is utilized in our study through the employment of the Cauchy problem in order to contract a system of nonlinear non-autonomous mixed-type integro-differential (ID) fractional evolution equations in infinite-dimensional Banach spaces. We reveal the existence of new mild solutions in the condition that the nonlinear function modifies approximately suitable, measure of non-compactness (MNC) form and local growth form using evolution classes along with fractional calculus (FC) theory as well as the fixed-point theorem with respect to k-set-contractive operator and MNC standard set. Consequently, as an example, we consider a fractional non-autonomous partial differential equation (PDE) with a homogeneous Dirichlet boundary condition and a non-instantaneous impulse condition. The conclusion of mild solution regarding the uniqueness and existence of a mild solution for a system with a probability density function and evolution classes is drawn with respect to the related domains.

Construction controllability for conformable fractional stochastic evolution system with noninstantaneous impulse and nonlocal condition

Conformable fractional stochastic differential equation with noninstantaneous impulse and Poisson jump via nonlocal condition is studied. Controllability for the considered problem is constructed. The required results are established based on fractional calculus, stochastic analysis, and Sadovskii’s fixed point theorem. Moreover, an example is provided to illustrate the applicability of the results.

Impulsive control and global stabilization of reaction‐diffusion epidemic model

In this paper, by using the variational method, a sufficient condition for the unique existence of the stationary solution of the reaction‐diffusion ecosystem is obtained, which directly leads to the global asymptotic stability of the unique equilibrium point. Moreover, delayed feedback ecosystem with reaction‐diffusion item is considered, and the above sufficient condition may not warrant the global stability for it. Utilizing impulse control results in its globally exponential stability. Besides, one of numerical examples shows that applying Laplacian semigroup in a newly obtained criterion is better than applying impulsive differential inequations, for the impulse condition becomes less harsh. It is worth mentioning that the Neumann zero‐boundary value that the infected and the susceptible people or animals should be controlled in the epidemic prevention area and not allowed to cross the border, which is a good simulation of the actual situation of epidemic prevention. And numerical simulations indicate the effectiveness of impulse control, which has a certain enlightening effect on the actual epidemic prevention work. That is, in the face of the epidemic situation, taking a certain frequency of positive and effective epidemic prevention measures is conducive to the stability and control of the epidemic situation. Particularly, the newly obtained theorems quantifies this feasible step.

New delay and order-dependent passivity criteria for impulsive fractional-order neural networks with switching parameters and proportional delays

This work deals with the problem of passivity analysis of fractional-order neural networks (FONNs) with impulse, proportional delays and state-dependent switching parameters. The novelty of the work lies in addressing the crucial issue of developing a delay-dependent LMI condition for analysing the behaviour of delayed FONNs. In this paper, a new lemma on Caputo fractional derivatives is developed to construct a new Lyapunov functional to derive delay dependent LMI condition for the passivity analysis of FONNs. Besides that, under modification, another sufficient condition is derived to give an impulse gain-dependent LMI condition. Moreover, for the first time in the literature, delay-dependent and order-dependent passivity criteria for fractional-order systems with proportional delays are presented in this paper. Finally, the results obtained are verified with suitable numerical parameter values and the simulation results are demonstrated to show the effectiveness of the proposed method and superiority of FONNs.

Research on calculation model of Tower Impulse resistancebased on EMTP

Accurate determination of impulse grounding resistance of tower grounding body is the premise to improve the lightning withstand level of transmission line. The current research mostly ignores the nonlinear effect of soil spark discharge. Based on the analysis of the idea and conception of the equivalent model of grounding body considering spark discharge effect, two simulation models based on EMTP are proposed. The two simulation models can well simulate the inductance effect and spark discharge effect when lightning current flows through grounding body, and improve the grounding body model under impulse condition. The comparison results show that the simulation results are in good agreement with the field measurement results.

Reliability Analysis of A Novel On-line Maintenance Switchgear Under Transient Impulse

To improve the efficiency of switchgear maintenance, a double-action switchgear is presented to realize the purpose of on-line maintenance in this paper. And to check the reliability and safety of the novel design, a research about the insulation performance of the new design switchgear under two different impulse action is carried out. The two different impulse phenomena refer the switching process of the double-action switchgear and the lighting impulse respectively. The switchgear conversion equivalent circuit is established to analyze the transient process of the switching and the mechanism of lightning surge strike on the switchgear is analyzed as well. Based on these, an 3D electric field model is established to calculate the distribution of electric field under switchgear transient condition and the lightning impulse condition respectively. The results show that when the new switchgear operates under the condition of the maximum overvoltage during the switching progress, the maximum field strength is 4.35×105V/m, which is less than the air breakdown field strength. Under the extreme conditions of lightning surge strike, the maximum field strength in the main switchgear and stand-by switchgear is 1.415×107V/m and 5.093×106V/m respectively, where the breakdown may occur. Lightning arresters is quite necessary to be adopted to protect the new switchgear.

Existence of solutions of non-autonomous fractional differential equations with integral impulse condition

In this paper, we investigate the existence of solution of non-autonomous fractional differential equations with integral impulse condition by the measure of non-compactness (MNC), fixed point theorems, and k-set contraction. The obtained results are verified via a supporting example.

Analyze of Metallic Powders on Content of the Oxygen, Nitrogen, Hydrogen Admixture

Properties of compact metals depend, in base, from oxygen, nitrogen and hydrogen conсentrations in their volumes. Powders have peculiarities, which distinguish from compact metals.
 Literature review on methods of determination oxygen, nitrogen and hydrogen of content in metallic powders.
 Main method of control of the gaseous admixture in metallic powders is method of the restoration melting of analytical metal in carring gas flow (helium, argon, nitrogen) in graphite crucible in impulse condition. Principal peculiarities and advantages of this method are enumerated.
 Examples of analysis of real objects — powders of pure metals and alloys (iron, chromium, manganese, ferromanganese, ferrosilicon, nickel alloys) is given.
 Samples preparation is the most difficult operation in the time of analyses of metallic powders (selection, manufacturing, drying, preservation, transport of analytical samples).
 Problems of calibration of the methods and analysers by standard samples are considerd.
 Problems of creation of the standard samples from powder metals with known oxygen, nitrogen and hydrogen concentration are considerd.
 Lack of the standard samples of metallic powders on gaseous admixtures (oxygen, nitogen, hydrogen) are showed.
 Method of determination oxygen, nitrogen and hydrogen contents in highalloyed nickel — tempe­rature of heating on graphite crucible, time, mass of analytical sample — are created.
 Materials for creation of the standard samples of powder metals with certain concetration gaseous admixture with good prospects — highalloyed nickel with low oxygen, nitrogen and hydrogen concentrations — are proposed.

Integration of Energy Balance of Soil Ionization in CIGRE Grounding Electrode Resistance Model

This paper proposes an improved CIGRE grounding electrode resistance model by integrating the energy balance of soil ionization. The main contribution of the improved CIGRE model is its accuracy to compute the time-dependent grounding electrode resistance under impulse condition. In addition, it can obtain correct resistance–current relation (hysteresis characteristic) of the grounding electrode. The accuracy of the improved CIGRE model is achieved by taking into account the effect of the arc resistance in soil, considering the energy balance of the soil ionization. The improved CIGRE model was validated for low resistivity soils ranging from 40 to 370 Ω·m. The comparison of the computed grounding electrode resistance obtained from the improved CIGRE model and experiment confirms the increase in the accuracy of the resistance and voltage response of the grounding electrode. The grounding electrode resistances obtained from the improved CIGRE model and experiments at current peak and current half value at decaying period (tail) have shown maximum differences of 3.5 and 2%, respectively. Moreover, precise voltage responses of grounding electrodes compared with the experimental results were obtained under different impulse currents.

Critical response evaluation of damped bilinear hysteretic SDOF model under long duration ground motion simulated by multi impulse motion

Multi impulse is used as a representative of a series of many-cycle harmonic waves which substantially simulate the long-duration earthquake event. An analytical formulation is developed for the elastic-plastic response of a single-degree-of-freedom (SDOF) damped structure with bilinear hysteresis under the critical multi impulse condition. Following the procedure for elastic-perfectly plastic models, a novel procedure using an energy balance law is introduced. In this procedure, under the multi impulse condition, only the free-vibration exists, hence the energy balance law can be applied easily. An approximate but effective treatment of the energy dissipated by the viscous damping is a new perspective. It is shown that based on an analytical solution, the critical maximum plastic deformation and the corresponding critical impulse timing can be determined in the steady state condition depending on the input values. To investigate the reliability and accuracy of the proposed approach, a comparison is made with the response analysis outcome to the corresponding sine wave as a representative of the long-duration earthquake ground motion (GM).

Does consanguinity increase the risk of mental illnesses? A population based study

The aim of this study was to assess the impact of consanguinity on risk for mental disorders especially in primary health care-PHC settings. It was decided to ascertain prevalence of common mental disorders and consanguinity. We set out to study the burden of commonest psychiatric disorders among consanguineous marriages at PHC using the WHO Composite International Diagnostic Interview (WHO-CIDI) and examine their symptom patterns and co-morbidity in Qatar. A prospective cross sectional study was carried out over a year between November 2011 to October 2012. A total of 2.000 Qatari subjects aged 18 to 65 years were approached; 1.475 (73.3%) gave consent and participated in this study. Prevalence of psychiatric disorders using the WHO Composite International Diagnostic Interview (CIDI, version 3.0) showed that six most common disorders were major depression disorders (18.3%), any impulse control condition (18.3%), any anxiety disorders (17.2%), any mood disorders (16.9%), followed by separation anxiety disorders (15.2%), personality disorder (14.1%). The mean age ± SD of the 1.475 subjects interviewed was 39.3 ± 9.8 years. The rate of consanguinity in the present generation was 31.5% [95% CI = 29.1–33.7]. There were statistically significant differences between consanguineous and non-consanguineous with regards to age, educational status, occupation status, household income as well as BMI, cigarette smoking and sheesha smoking. One-fifth of all adults who attended the PHC center 20% had at least one psychiatric diagnosis. The prevalence of the generalized anxiety disorders; social phobia, specific phobia, major depression, and personality disorders were significantly higher in consanguineous marriages than in non-consanguineous.Disclosure of interestThe author has not supplied his declaration of competing interest.

Graphene plasmon modes on slab waveguides at telecom wavelengths

In this study, the transversal magnetic (TM) and electric (TE) modes of graphene plasmon in a homogeneous environment and three-layered systems were theoretically investigated. The dispersion relations of the graphene plasmon modes were derived in the framework of classical electrodynamics with plane wave modes and Neumann-Dirichlet boundary conditions. The graphene plasmon modes in the three-layer system reproduced exactly the same dispersion relations as freestanding graphene (Phys. Rev. Lett. 99, 016803 (2007)), as all layers had the same refractive index. The impulse matching condition between the graphene plasmon and guided photons and the propagation decay length of graphene plasmon were investigated by numerically solving the dispersion relations for different values of the Fermi-energy and the refractive index of the upper layer. The TE-mode graphene plasmon has potential for applications of graphene as a polarization-selective modulator due to its convenient impulse matching with guided photons in the region of telecom wavelengths, despite its low propagation decay rates.

A Comprehensive Approach for Transient Performance of Grounding System in the Time Domain

It is important to identify the impulse performance of the grounding system for lightning protection. However, the performance is nonlinear and dynamic under impulse condition. The electrical parameters of the grounding system are not only frequency dependent, but are also time dependent. Moreover, the mutual couplings between the grounding conductors cannot be ignored. Based on the hybrid electromagnetic method and vector fitting, a time-domain approach for the transient performance of the grounding system is developed. All the aforementioned phenomena can be covered in this method. Meanwhile, the sudden change of the parameters resulting from the soil ionization is also successfully dealt with in this paper. Compared with previous study results and field tests, the method proves to be reliable and effective.

Oscillation and stability of first-order delay differential equations with retarded impulses

In this paper, we study both the oscillation and the stability of impulsive differential equations when not only the continuous argument but also the impulse condition involves delay. The results obtained in the present paper improve and generalize the main results of the key references in this subject. An illustrative example is also provided.

A molecular dynamics and finite elements study of nanoscale thermal contact conductance

We study scale effects on the conductivity of crystalline contacting interfaces. The approach focuses on the role played by lattice vibrations in the thermal conductivity using finite elements and molecular dynamics models. A special effort is made at calibrating the continuum model directly from molecular dynamics simulations. An innovative method that uses the temperature evolution issued from an impulse boundary condition is employed to compute heat conductivity, which is notoriously known as difficult to measure. Using this approach, a parametric study is conducted on a set of contacting surfaces on which we specify asperities wavelengths. It is shown that the usual power laws that relate contact area ratio with thermal conductivity do not apply at the nanoscale.

Attractors of impulsive dissipative semidynamical systems

In this paper, we consider a class of dissipative semidynamical systems with impulses. First, we study the connectedness of Levinsonʼs center of a compact dissipative system with impulses. Second, we define some types of attractors for dissipative systems and we study results which relate attractors and dissipative systems (point, bounded and compact). Finally, we apply our results for a general impulsive autonomous system and for a nonlinear reaction–diffusion equation of type u′−Δu+g(u)=f with impulse condition.

액체질소 내에서 뇌 임펄스전압에 대한 압력별 GFRP의 절연파괴 특성 분석

A study on the dielectric characteristics of the Glass Fiber Reinforced Plastic (GFRP) is important for designing a reliable high voltage superconducting machines such as transmission superconducting fault current limiters, superconducting cables, and superconducting transformers. In this paper, dielectric experiments of the GFRP under lightning impulse voltage are conducted in liquid nitrogen(LN₂) according to various experimental conditions such as the thicknesses of the GFRP, the diameters of electrode systems and the pressures. The dielectric characteristics of the GFRP are analyzed by using a Finite Elements Method(FEM) according to various field utilization factors. It has been reported that the electrical insulation design of the GFRP would be conducted by considering the mean electric field intensity(Emean) distributed inside the GFRP. In this study, it is found that the dielectric performance of the GFRP could be explained by not only Emean but also the maximum electric field intensity (Emax). Finally, the empirical formulae of the GFRP to estimate an electrical breakdown voltage at sparkover under the lightning impulse condition are deduced. It is expected that the presented experimental results in this paper are helpful to design electrically reliable high voltage superconducting machines using the GFRP as an insulation material.