Influence Of Electrical Conductivity Research Articles

Discharge in air in contact with water: influence of electrical conductivity on the characteristics and the propagation dynamics of the discharge

Due to the high reactivity and the non-thermal properties of streamer discharges, they are applied in various fields, such as water treatment and medicine. Streamer discharges are usually produced in the gas phase before interacting with a liquid or solid surface. Although the dynamics of a streamer discharge in gases is well described, its propagation at liquid surfaces remains poorly understood. In this study, we investigate the influence of water electrical conductivity (σ), between 2 and 1000 µS cm−1, on the characteristics and propagation dynamics of pulsed positive DC nanosecond discharges with the solution serving as a cathode. σ strongly influences τ r (the dielectric relaxation time), and two discharge modes may be obtained, depending on whether τ r is shorter or longer than the delay to achieve breakdown (τ pulse). This latter can be indirectly modified by adjusting the voltage amplitude (V a). In the case of V a = 14 kV, the breakdown voltage (V bd) at low σ is lower than that measured at high σ, probably because τ pulse < τ r and > τ r, respectively. In the case of V a = 20 kV, V bd decreases slightly with σ, probably because of the decrease of the resistivity of the global electrical circuit as τ pulse ∼ τ r for high σ. In addition to the electrical characterization, the dynamics of the discharge at the solution’s surface is investigated using 1 ns-time-resolved imaging. Its morphology was found to evolve from a disc to a ring before it splits into highly organized plasma dots (streamers’ head). The number (N dots) and propagation velocity of plasma dots are determined as a function of σ. At V a = 14 kV, N dots does not vary significantly with σ despite the increase of V bd; this latter likely compensates the neutralization of charge accumulated at the surface by ions in solution. In the case of V a = 20 kV, N dots decreases with σ, and it can be related to a decrease of accumulated charge at the water surface. Finally, based on the electrical measurements, we found that the charge per plasma dot (Q dot) increases with σ, which does not correlate with the imaging results that show a short length of propagation at high σ. Then, considering the plasma dot mobility at low σ and the instantaneous propagation velocities at high σ, a more realistic Q dot is measured.

Mineral nutrition in orchids

The Orchidaceae family stands out when it comes to the commercialization of pot flowers, this is due to their flowers being widely attractive and have variability of colors, size and shapes according to the species; this results in plants with high relevance to the economy in the floriculture sector. The goal of this study was to elucidate questions about the effect of micronutrients on initial growth, the influence of electrical conductivity and frequency of fertilizer application, and the efficiency of organic fertilization with castor bean cake, on the growth and nutrition of Brassia verrucosa Lindley orchid. Studies with mineral fertilization involving nitrogen (N), phosphorus (P) and potassium (K) in Cattleya and Phalaenopsis seedlings allowed to obserevar that the N increment increased the number of flowers in Cattleya, while P and K did not affect this variable. The salinity of irrigation water also has an effect on growth and flowering. The electrical conductivity, the sources of fertilizers, their interaction with the substrate, the balance between the nutrients, the quantities and frequencies to be used, in addition to the different phenological requirements and characteristics intrinsic to the species, are important aspects to be considered in fertirigation.

Two different new Tamarix smyrnensis Bunge associations on the Yeşilırmak Delta Plain (Samsun/Türkiye)

The aim of this paper is to deal with syntaxonomical and ecological characteristics of Tamarix smyrnensis communities developed on both salt marsh and riparian habitats of the Yeşilırmak Delta Plains. The floristic composition of the communities was analysed by Braun-Blanquet method and the effect of edaphic parameters on the communities were determined using ordination techniques (CCA). The habitat types were identified according to the European Nature Information System (EUNIS) habitat coding list. Junco acuti-Tamaricetum smyrnensis ass. nov. developed on salt marshes and belonging to the alliance of Tamaricion tetragynae, and Tamaricetum tetrandrae-smyrnensis ass. nov. developed on meander banks/river island (eyot) and belonging to the alliance of Rubo sancti—Nerion oleandri distributed under influence of electrical conductivity (EC) of soil. Additionally, it was observed that both associations belonged to subunits of Mediterraneo-Macaronesian tamarisk thickets according to EUNIS.

Influence of Electrical Conductivity on Heating Power of Metal Billets in HTS DC Induction Heater

A novel high-temperature superconducting (HTS) direct current induction heater exhibits great advantages such as high efficiency and superior heating quality for non-magnetic metal billet heating process in industrial applications. An HTS induction heater of 1 MW is used in the Al press industry. The HTS induction heater injects high resistive heating power through the driving motor. The higher the resistive heating power, the shorter the heating time. The heating power is a significant parameter used to analyze the heating time and improve the production efficiency. In this study, three types of non-magnetic metal billets were analyzed, including Al, TC4 (Ti-6AL-4V), and Cu, which are widely used in the heating process in industrial applications. The experimental results of the heating of TC4 and Al billets (Φ = 220 mm × L = 1,250 mm) using an HTS induction heater were obtained. The changing trend of the heating power during heating was different. The heating power of TC4 was different from those of Al and Cu. The heating power of TC4 was much lower than those of Al and Cu. A numerical 3-D finite element method model was built to analyze the heating power. The results of the simulation and experiments were consistent with each other. The electrical conductivity of the billet is a significant material property affecting the heating power. Finally, the influence of the billet diameter on heating behavior was analyzed for the three different metal billets. Understanding the effect of electrical conductivity of important industrial metals such as Al, Ti, and Cu alloys on heating power is useful for improving metal processing technologies.

Effect of core electrical conductivity on core surface flow models

The electrical conductivity of the Earth’s core is an important physical parameter that controls the core dynamics and the thermal evolution of the Earth. In this study, the effect of core electrical conductivity on core surface flow models is investigated. Core surface flow is derived from a geomagnetic field model on the presumption that a viscous boundary layer forms at the core–mantle boundary. Inside the boundary layer, where the viscous force plays an important role in force balance, temporal variations of the magnetic field are caused by magnetic diffusion as well as motional induction. Below the boundary layer, where core flow is assumed to be in tangentially geostrophic balance or tangentially magnetostrophic balance, contributions of magnetic diffusion to temporal variation of the magnetic field are neglected. Under the constraint that the core flow is tangentially geostrophic beneath the boundary layer, the core electrical conductivity in the range from {10}^{5} ~mathrm{S}~{mathrm{m}}^{-1} to {10}^{7}~ mathrm{S}~{mathrm{m}}^{-1} has less significant effect on the core flow. Under the constraint that the core flow is tangentially magnetostrophic beneath the boundary layer, the influence of electrical conductivity on the core flow models can be clearly recognized; the magnitude of the mean toroidal flow does not increase or decrease, but that of the mean poloidal flow increases with an increase in core electrical conductivity. This difference arises from the Lorentz force, which can be stronger than the Coriolis force, for higher electrical conductivity, since the Lorentz force is proportional to the electrical conductivity. In other words, the Elsasser number, which represents the ratio of the Lorentz force to the Coriolis force, has an influence on the difference. The result implies that the ratio of toroidal to poloidal flow magnitudes has been changing in accordance with secular changes of rotation rate of the Earth and of core electrical conductivity due to a decrease in core temperature throughout the thermal evolution of the Earth.

Toward subsurface magnetic permeability imaging with electromagnetic induction sensors: Sensitivity computation and reconstruction of measured data

In near-surface geophysics, small portable loop-loop electromagnetic induction (EMI) sensors using harmonic sources with a constant and rather small frequency are increasingly used to investigate the electrical properties of the subsurface. For such sensors, the influence of electrical conductivity and magnetic permeability on the EMI response is well-understood. Typically, data analysis focuses on reconstructing an electrical conductivity model by inverting the out-of-phase response. However, in a variety of near-surface applications, magnetic permeability (or susceptibility) models derived from the in-phase (IP) response may provide important additional information. In view of developing a fast 3D inversion procedure of the IP response for a dense grid of measurement points, we first analyze the 3D sensitivity functions associated with a homogeneous permeable half-space. Then, we compare synthetic data computed using a linear forward-modeling method based on these sensitivity functions with synthetic data computed using full nonlinear forward-modeling methods. The results indicate the correctness and applicability of our linear forward-modeling approach. Furthermore, we determine the advantages of converting IP data into apparent permeability, which, for example, allows us to extend the applicability of the linear forward-modeling method to high-magnetic environments. Finally, we compute synthetic data with the linear theory for a model consisting of a controlled magnetic target and compare the results with field data collected with a four-configuration loop-loop EMI sensor. With this field-scale experiment, we determine that our linear forward-modeling approach can reproduce measured data with sufficiently small error, and, thus, it represents the basis for developing efficient inversion approaches.

Stress detection and measurement in ferromagnetic metals using pulse electromagnetic method with U-shaped sensor

Abstract This paper proposed a pulse electromagnetic method (PEM) with a specially designed U-shaped sensor to detect and measure stress in ferromagnetic metals, which is derived from pulsed eddy current (PEC) and pulse magnetic flux leakage (PMFL). At first, theory behind PEM for tensile stress measurement has been analyzed. The influences of electrical conductivity and magnetic permeability of ferromagnetic material on sensor’s response have been investigated through finite element method (FEM). Experimental system has been built and the experimental studies have been carried out to obtain the relationship between stress and extracted features from difference response of PEM U-shaped sensor. The excitation frequency has been optimized to improve the sensitivity. Both simulation and experimental results indicate that the proposed PEM can be used to measure and quantify the unidirectional tensile stress in ferromagnetic specimen due to the linear relationship in elastic deformation. The relationship between sensitivity and frequency is a reverse power function, and low frequency excitation has a higher sensitivity on stress measurement.

Design and calibration of a new compound sensor for water content and electrical conductivity in soilless substrates

Reliable and affordable compound sensors for measuring the water content and electrical conductivity simultaneously in soilless substrates are limited. In this study, a new compound sensor based on dielectric theory and four-electrode method is presented, and the size of the sensor is determined with the help of ANSYS software. A water content calibration test is designed in vinegar residue and coconut chaff with the same electrical conductivity. Test results show that the water content calibration equation is suitable for different substrates. Similarly, an electrical conductivity calibration equation is obtained in different concentrations of salt solutions. Considering the influence of electrical conductivity to water content measurement, a two-factor (water content and electrical conductivity) orthogonal test is designed in coconut chaff. Based on the analysis of test results, two compensation models – the multiplicative model and the additive model – are proposed. To evaluate the reliability of the models, a multiple linear regression analysis is employed. The results indicate that the additive model has a relatively higher reliability, i.e. the additive model can be regarded as the compensation model. After compensation, the relative errors of the measured values (including volumetric water content and electrical conductivity) are no more than 10%, and the compound sensor is suitable for different soilless substrates without recalibration.

Influence of electrical conductivity on water uptake and vase life of cut gladiolus stems

&lt;p&gt;Several experiments reveal that distilled water varies among different laboratories and also does not have a standard composition. Water electrical conductivity (EC) of vase solution is one of the parameters that influence the water uptake by cut flowers. Therefore, the objective of this work was to evaluate the influence of electrical conductivity on water uptake and vase life in cut stems of gladiolus. The stems harvested and kept in distilled water (pH 6.6, EC &amp;lt;0.01dS m-1) and tap water (pH 7.0, EC 0.75 dS m-1) at room temperature. Flowers kept in tap water showed lower fresh weight loss after the second day and higher water uptake during vase life. In a second set of experiments, we verified the limit EC saturation supported by the flower. For this, flowers were placed in individual test tubes containing four different solutions with varying ion concentrations. Solution 2 (EC 0.60 dS m-1) promoted increased vase life and allowed maximum water uptake by the flowers. The results show that the electrical conductivity of vase solution is a major parameter in experiments with vase life of cut gladiolus. The presence of ions in the vase solution increases the overall vase life and improves water uptake of flowers with favorable optimal EC between 0.60 to 0.87 dS m-1.&lt;/p&gt;

Influence of electric conductivity on intensity factors for cracks in functionally graded piezoelectric semiconductors

Influence of electric conductivity on intensity factors for cracks in conducting piezoelectric materials is investigated. Mechanical and electric loads are considered for 2D crack problems. The electric displacement in conducting piezoelectric materials is influenced by the electron density and it is coupled with the electric current. The coupled governing partial differential equations (PDE) for stresses, electric displacement field and current are satisfied in a local weak-form on small fictitious subdomains. Nodal points are spread on the analyzed domain and each node is surrounded by a small circle for simplicity. Local integral equations are derived for a unit function as the test function on circular subdomains. All field quantities are approximated by the moving least-squares (MLS) scheme. Interaction integral method is developed for evaluating the intensity factors in functionally graded conducting piezoelectric materials.

Mathematical simulation of electromagnetic wave diffraction by grid polarization structures

Electromagnetic characteristics of metal polarization gratings are studied by means of the finite-difference time-domain technique in the case of long-wavelength diffraction of electromagnetic waves. Dimensions of gratings with rectangular bridges providing for optimal regimes of propagation of H- and E-polarized waves at the boundary between the microwave and terahertz ranges are determined. The influence of electric conductivity of metal elements on the transmission characteristics of the gratings is analyzed.

Diatom–environment relationships and a transfer function for conductivity in lakes of the Badain Jaran Desert, Inner Mongolia, China

We describe a dataset of 26 modern diatom samples and associated environmental variables from the Badain Jaran Desert, northwest China. The influence of electrical conductivity (EC) and other variables on diatom distribution was explored using multivariate analyses and generalized additive modeling of species response curves. A transfer function was derived for EC, the variable with the largest unique effect on diatom variance, as shown by partial canonical correspondence analysis. Weighted-averaging partial least squares regression and calibration provided the best model, with a high coefficient of determination ( $$ {\text{r}}_{\text{boot}}^{2} $$ = 0.91) and low prediction error (RMSEPboot = 0.136 log10 μS cm−1). To assess its potential for palaeosalinity and palaeoclimate reconstructions, the EC transfer function was applied to fossil diatom assemblages from 210Pb-dated short sediment cores collected from two subsaline lakes of the Badain Jaran Desert. The diatom-inferred (DI) EC reconstructions were compared with meteorological data for the past 50 years and with remote sensing data for the period AD 1990–2012. Changes in DI–EC were small and their relationship with climate was weak. Moreover, remote sensing data indicate that the surface areas and water depths of these lakes did not change, which suggests that water loss by evaporation is compensated by groundwater inflow. These results suggest that the response of these lakes to climate change is mediated by non-climatic factors such as the hydrogeological setting, which control recharge from groundwater, and may be non-linear and non-stationary.

Influence of Electrical Conductivity of Nonmagnetic Conductor in Electrodynamic Suspension Device using AC Electromagnets Driven by High Frequency Current

Influence of Electrical Conductivity of Nonmagnetic Conductor in Electrodynamic Suspension Device using AC Electromagnets Driven by High Frequency Current

Numerical Study of Fundamental Magnetoconvection Phenomena in Electrically Conducting Ducts

In the currently proposed helium-cooled lead lithium blanket design, the liquid metal serves mainly to breed tritium, and the heat flux is removed by helium flowing at high pressure in channels grooved in the walls. The use of a separate coolant has the advantage that the liquid metal can flow in the blanket with smaller velocities compared to those required in self-cooled blanket concepts. As a result, the buoyant convective flow caused by nonuniform thermal conditions and gravity may be comparable or even exceed the forced flow foreseen for tritium removal. Therefore, the knowledge of buoyancy-driven magnetohydrodynamic flows becomes fundamental to understand how the liquid metal circulates in the blanket. In this paper, the main characteristics of magnetoconvective duct flows are described. Effects of the direction of the temperature gradient with respect to the orientation of the applied magnetic field and the influence of electric conductivity of walls on the flow structure are investigated numerically.

The Study of Acid Doped Polyaniline Anticorrosive Coatings

This topic in the reaction temperature, reaction time for 5 °C for 7 hours, aniline and ammonium persulfate mole ratio of 1:1 conditions, main research on synthesis of concentration of reactant polyaniline performance, yield, the influence of electric conductivity. By ir, conductivity meter, scanning electron microscope (sem) analysis of samples, and the results show that when the yankees salicylic acid concentration sulfonylureas 0.15-0.25 mol/L, ammonium persulfate concentration 0.1-0.2 mol/L got when the production rate is higher, anticorrosive performance is good polyaniline coatings.

Influence of electrical conductivity on biological activity of Pythium ultimum and Binab T in a closed soilless system

The effects of electrical conductivity (EC) of the nutrient solution on the performance of the commercial biocontrol product Binab T against the root pathogen Pythium ultimum were studied in order to identify supporting factors to increase the efficiency and decrease the inconsistency of biocontrol agents in closed cultivation systems. Using a substrate-based growing system, the commercial product Binab T with the active strains Trichoderma polysporum plus T. harzianum was evaluated at four different EC levels (1.5, 2.5, 3.5 and 5.0 mS cm−1) over seven weeks in a controlled climate chamber environment, using tomato as the model plant. Addition of the biocontrol agent to the cultivation system caused a reduction in the level and incidence of pathogen attack that improved with increasing EC level from 2.5 mS cm−1 onward. Production of the cell wall-degrading enzymes cellulase and glucanase by Binab T increased with increasing EC level, independent of pathogen presence. In a control treatment with no artificial inoculation, enzyme activity decreased with increasing EC level. Increasing EC levels in the presence of Binab T also had a positive effect on plant biomass. The highest antagonistic effect of Binab T against Pythium ultimum, as indicated by enzyme activity, amount of pathogen in the system and disease incidence, occurred at 3.5 mS cm−1. The plant growth-promoting effect of Binab T also peaked at 3.5 mS cm−1.

Influence of nighttime electrical conductivity of substrate solution on fruit cracking and blossom‐end rot of greenhouse tomato in the tropics

AbstractThe influence of the electrical conductivity (EC) of the substrate solution during the night, i.e., moderately high EC (“HEC”, 3.0 dS m–1, full solution) and low EC (“LEC”, 0.5 dS m–1, CaCl2 or Ca(NO3)2 and H3BO3), on the incidences of blossom‐end rot (BER) and fruit cracking (FC) in greenhouse tomato (Solanum lycopersicum L.) was investigated and compared with a control without additional nighttime fertigation (NTF). In three consecutive experiments conducted in Central Thailand between November 2005 and March 2007, additional NTF cycles were applied for 1 h after the regular daytime fertigation (EC 1.5/1.8 dS m–1, prior to/after the first harvest). In the first experiment (dry season 2005/06), two cultivars with either low (FMTT 260) or high (King Kong 2) susceptibility to BER and FC were used. The total amount of fruits affected by FC or BER was 4‐ and 10‐fold, respectively, higher in King Kong 2, but the relative response to NTF was similar in both cultivars. Therefore, in the following experiments only FMTT 260 was planted. In all experiments, NTF exerted significant effects on the uptake and allocation of water and mineral elements to the fruits and the proportions of fruits affected by BER and FC. The overall proportion of nonmarketable fruits was not significantly reduced, neither through LEC nor HEC because a decrease in BER by LEC and in FC by HEC was counteracted by enhanced FC in LEC and BER in HEC. It is concluded that under the tropical climate conditions of Central Thailand leading to high losses of marketable fruit yield through BER and FC, an integrated approach is required combining an optimized management of the fertigation system and particularly the selection of genotypes highly tolerant of BER and FC.

Magnetic susceptibility and electrical conductivity of metallic dental materials and their impact on MR imaging artifacts

Objectives The aim of this study was to test the hypothesis that dental materials vary significantly in MR-relevant material parameters—magnetic susceptibility and electrical conductivity, and that knowledge of these parameters may be used to estimate the quality of MR imaging in the presence of devices made of such materials. Methods Magnetic susceptibility, electrical conductivity and artifacts were evaluated for 45 standardized cylindrical samples of dental alloys and amalgams. Magnetic susceptibility was determined by fitting the phase of gradient-echo MR images to numerically modeled data. Electrical conductivity was determined by standard electrotechnical measurements. Artifact sizes were measured in spin-echo (SE) and gradient-echo (GE) images at 1.5 T according to the standards of the American Society for Testing and Materials. Results It has been confirmed that dental materials differ considerably in their magnetic susceptibility, electrical conductivity and artifacts. For typical dental devices, magnetic susceptibility differences were found of little clinical importance for diagnostic SE/GE imaging of the neck and brain, but significant for orofacial imaging. Short-TE GE imaging has been found possible even in very close distances from dental devices made of amalgams, precious alloys and titanium alloys. Nickel–chromium and cobalt–chromium artifacts were found still acceptable, but large restorations of aluminum bronzes may preclude imaging of the orofacial region. The influence of electrical conductivity on the artifact size was found negligible. Significance MR imaging is possible even close to dental devices if they are made of dental materials with low magnetic susceptibility. Not all materials in current use meet this requirement.

Influence of electrical conductivity on microorganisms and rate of crude oil mineralization in Niger Delta ultisol

Influence of electrical conductivity on microorganisms and rate of crude oil mineralization in Niger Delta ultisol

Influence of electrical conductivity on microorganisms and rate of crude oil mineralization in Niger Delta Ultisol

The effect of salinity on the population density of hydrocarbonoclastic microorganisms and oil degradation in a tropical ultisol was determined. Soils were simulated with 50gkg-1 of Qua Iboe Light (QIL) crude oil. Salt treatments included NaCI amendments to adjust the soil solution electrical conductivities (EC) to 40, 120 and 200 dSm-1. Treated soils were incubated at 28OC. Oil degradation was estimated from the gravimetric determinations of remaining oil. The results showed that amending the ultisol with crude oil stimulated the growth of oil degrading microorganisms, while salt concentration inducing an EC of 200 dSm-1 in oil amended ultisol resulted in a decrease in the amount oil mineralized. A significant positive correlation was found between the number of hydrocarbonoclastic microorganisms and levels of oil mineralization at EC 40 dSm-1 (r = 0.980, P = 0.05) and EC 120 dSm-1 (r = 0.976. P = 0.05) except at EC 200 dSm-1 (r = 0.855, P = 0.05). This is an indication that desalting of soils contaminated with oil and salts is required for a speedy bioremediation of an ultisol. Key words: Electrical conductivity, crude oil, hydrocarbonoclastic microorganismineralization. (Global Journal of Pure and Applied Sciences: 2003 9(4): 475-480)