Changes In Electrical Parameters Research Articles

Eco-friendly modification of a regenerated cellulose based film by silicon, carbon and N-doped carbon quantum dots

Modification of a regenerated cellulose thin film by inclusion of different non-toxic nanodots (silicon-dots (SiDs), carbon-dots (CDs)) or nitrogen-doped carbon dots (N-CDs)) by aqueous nanodots solution immersion was performed. Nanodots presence into the cellulosic structure was evidenced by confocal microscopy images at different depth and changes in film mechanical, electrical and optical parameters. Our results reveal that the inclusion of the different nanodots in the cellulosic support increases, indifferent percentages, the mechanical resistance and electrical conductivity of modified films, but they hardly affect light transmittance. Particularly, modification with N-CDs largely favored film conductivity due to the presence of the higher number of charged functional groups (CNH2 and OCNH2) groups) on N-CDs surface, allowin gus the attainment of a flexible, fluorescent and transparent high conductive eco-friendly film. In fact, the non-toxic character of both support-film and nanodots, endorses the use of these new nano-engineering films in biomedical applications.

Bias temperature instability and condition monitoring in SiC power MOSFETs

Threshold voltage shift due to bias temperature instability (BTI) is a major concern in SiC power MOSFETs. The SiC/SiO2 gate dielectric interface is typically characterized by a higher density of interface traps compared to the conventional Si/SiO2 interface. The threshold voltage shift that arises from BTI has significant implications on the reliability of SiC power MOSFETs, hence, techniques for detecting the change in electrical parameters due to gate oxide degradation are desirable. Using accelerated high temperature gate bias stress tests on SiC MOSFETs, it has been shown that the output and transfer characteristics are affected by BTI. This paper presents the impact BTI induced threshold voltage shift on the forward voltage of the SiC MOSFET body diode during third quadrant operation. Using the forward voltage of the body diode during reverse conduction of low currents, threshold voltage shift can be detected, hence, the impact of BTI can be evaluated. The implications of the body diode forward voltage shift on junction temperature measurements are also studied in the context of TSEPs. The findings in this paper are important for engineers seeking to implement condition and health monitoring techniques on SiC power devices.

Advanced oxidation technology for H2S odor gas using non-thermal plasma

Non-thermal plasma technology is a new type of odor treatment processing. We deal with H2S from waste gas emission using non-thermal plasma generated by dielectric barrier discharge. On the basis of two criteria, removal efficiency and absolute removal amount, we deeply investigate the changes in electrical parameters and process parameters, and the reaction process of the influence of ozone on H2S gas removal. The experimental results show that H2S removal efficiency is proportional to the voltage, frequency, power, residence time and energy efficiency, while it is inversely proportional to the initial concentration of H2S gas, and ozone concentration. This study lays the foundations of non-thermal plasma technology for further commercial application.

Effects of a Thin Ru-Doped PVP Interface Layer on Electrical Behavior of Ag/n-Si Structures

The aim of this study is to improve the electrical property of Ag/n-Si metal–semiconductor (MS) structure by growing an Ru-doped PVP interlayer between Ag and n-Si using electrospinning technique. To illustrate the utility of the Ru-doped PVP interface layer, current–voltage (I–V) characteristics of Ag/n-Si (MS) and Ag/Ru-doped PVP/n-Si metal–polymer–semiconductor (MPS) structures was carried out. In addition, the main electrical parameters of the fabricated Ag/Ru-doped PVP/n-Si structures were investigated as a function of frequency and electric field using impedance spectroscopy method (ISM). The capacitance–voltage (C–V) plot showed an anomalous peak in the depletion region due to the special density distribution of interface traps/states (Dit/Nss) and interlayer. Both the values of series resistance (Rs) and Nss were drawn as a function of voltage and frequency between 0.5 kHz and 5 MHz at room temperature and they had a peak behavior in the depletion region. Some important parameters of the sample such as the donor concentration atoms (ND), Fermi energy (E F ), thickness of the depletion region (WD), barrier height (Φ B0 ) and R s were determined from the C−2 versus V plot for each frequency. The values of N D , W D , Φ B0 and R s were changed from 1 × 1015 cm−3, 9.61 × 10−5 cm, 0.94 eV and 19,055 Ω (at 0.5 kHz) to 0.13 × 1015 cm−3, 27.4 × 10−4 cm, 1.04 eV and 70 Ω (at 5 MHz), respectively. As a result of the experiments, it is observed that the change in electrical parameters becomes more effective at lower frequencies due to the Nss and their relaxation time (τ), dipole and surface polarizations.

Synthesis and characterisation of electro-rheological property of novel eco-friendly rice bran oil and nanofluid

In this study, thermophysical properties: electrical properties, viscosity, refractive index and density of rice bran oil (RBO), RBO added with antioxidants (RBOA), RBOA added with nanoparticle like ZnO and ZnZrO were investigated. Ensuring the quantification of the elements in nanoparticle, morphological study was conducted using SEM (Scanning Electron Microscope). Variation of electrical and rheological properties of base fluid and nanofluid at different temperatures and frequency was investigated. Changes of electrical parameters in the frequency range 1Hz to 10MHz of microwave region was experimented. Using Stokes–Einstein equation: diffusion time and diffusion constant were calculated and the enhancement of viscosity was obseved to vary with agglomeration. In addition specific refractive index, specific polarisation and orientation polarisation of the samples were also estimated. Vicissitudes of electrical parameters and viscosity was experimental with temperature ranging from 303K to 373K. Shear property of the samples were studied on heating and cooling and the results confirms that shear variation does not affect the stability of nanofluid with temperature. In order to validate the results, modeling has been carried out using Arrhenius and Andrades models for the electrical parameters with temperature and for which the regression coefficient R2 is 0.918 to 1.0. The present study helps to use the nanofluid in the appropriate industrial applications.

Small intestinal ischemia and reperfusion—bioimpedance measurements

Objective: Trans-intestinal bioimpedance measurements have previously been used to investigate changes in electrical parameters during 6 h of ischemia in the small intestine. Knowledge is lacking regarding the time course of trans-intestinal bioimpedance parameters during reperfusion. As reperfusion is an important part in the clinical treatment of intestinal ischemia, we need to know how it affects the bioimpedance measurements. Approach: We performed bioimpedance measurements, using a two-electrode setup on selected segments of the jejunum in 15 pigs. A controlled voltage signal was applied while measuring the resulting current. In each pig, five or six 30 cm segments of the jejunum were made ischemic by clamping the mesenteric arteries and veins creating segments with ischemia from 1–16 h duration. Reperfusion was initiated at selected time intervals of ischemia, and measured for 5–15 h afterwards. Main results: The tan δ parameter (loss tangent) was different (p < 0.016) comparing ischemic and control tissue for the duration of the experiment (16 h). Comparing the control tissue 30 cm from the ischemic area with the control tissue 60 cm from the ischemic tissue, we found that the mean tan δ amplitude in the frequency range (3900–6300 Hz) was significantly higher (p < 0.036) in the proximal control after 10 h of experiment duration. After reperfusion, the time development of tanδm (loss tangent maximum over a frequency range) amplitude and frequency overlapped and periodically increased above the tanδm in the ischemic intestine. Dependent on the ischemic duration pre-reperfusion, the initial increase in tan δ stabilizes or increases drastically over time, compared to the tan δ amplitude of the ischemic tissue. Significance: As during ischemia, the electrical parameters during reperfusion also follow a characteristic time-course, depending on the ischemic exposure before pre-reperfusion. The temporal changes in electrical parameters during small intestinal ischemia followed by reperfusion provides important information for assessment of tissue injury.

New generation implantable cardiac rhythm devices allow safe radiotherapy treatments: A large single centre study

INTRODUCTION: Many patients requiring radiotherapy for malignancies have an already implanted cardiac rhythm device. Previous studies reported a variety of device dysfunctions related to high dose radiation. Aim of this study was to assess the impact of current optimal radiotherapy treatment guided by computed tomography on current generation implantable devices. METHODS: Consecutive patients with implanted pacemakers (PMK) and implantable cardioverter defibrillators (ICD) referred for radiotherapy treatment in any district were enrolled at our Centre and followed prospectively with device interrogation before and just after each radiotherapy cycle. A magnet was positioned on the device in patients with implanted defibrillators or pacemaker-dependency. RESULTS: Overall, 48 patients (74.8 years (9.3), 39 males (81.3)) with implantable devices underwent radiotherapy (29 pacemakers and 19 ICDs). Interval between device implant and start of radiation therapy was 2.9 (1.6) years. Radiotherapy was performed under computed tomography guidance, and a mean of 73.5 (45.0) Gy were administered with a mean of 24.8 (14.6) fractionated doses. About half of the patients underwent thoracic radiotherapy, and 9 were treated for a left thoracic malignancy ipsilateral to the implanted device. No device failures were observed at post-treatment device interrogation, nor changes in electrical parameters, inappropriate shocks, device reprogramming or memory reset. None of the patients experienced premature battery failure or other unexpected anomalous findings at the end of the radiation therapy cycle. CONCLUSION: Radiation therapy for malignancies is safe among patients with implanted current generation cardiac rhythm devices.

Simulation and Experimental Fault Analysis of Grid Tied Solar Photo-Voltaic System

Use of renewable energy sources is encouraged to ensure the continuous supply of electricity to the customers. The system may sometimes face problems due to internal and external factors, which leads to the faults in the system. This paper presents simulation and experimental study on the effect of phase faults in grid connected solar photovoltaic plant. The effect of faults because of internal and external factors has been analyzed with the simulations of synchronized 200kW grid tied solar photovoltaic system using MATLAB and experimental analysis of faults in 500W of prototype grid connected system. Therefore it is necessary to examine the fault ride through capability of the system, so that the power production capacity of a solar photovoltaic system can be enhanced. The variations in solar irradiance level and temperature influences the power output from the plant and an incremental inductance maximum power point tracking technique is applied to get the peak power output. Thus, the changes in electrical parameters and solar system behavior in faulty conditions has been examined.

Electrical Detection, Identification, and Quantification of Exosomes

Exosomes are intercellular communication vehicles containing cell-specific molecules that can be quantified using different biochemical or biophysical techniques. This paper explores the use of capacitance-voltage electrical measurements for the label-free detection, identification, and quantifications of exosomes. With the application of voltage, an interface effective layer is formed because of the interaction between the exosome surface and its surrounding media. The exosomes store electrical energy when electrically polarized, thus enabling its electrical detection. A specific electrical capacitance-voltage profile is attributed to the precise nature of the respective exosomes, which helps in both identification and quantification. The exosome count is estimated by calculating the impurities inside a defined volume by observing the changes in electrical parameters extracted from the capacitance-voltage measurements. This technique could be applied to count suspended silica and liposomes nanoparticles as well. This approach was found to be faster and less expensive than other existing techniques.

Electrical Characterization of Normal and Cancer Cells

In this paper, we characterize and discriminate between normal and cancer cells from three different tissue types, liver, lung, and breast, using capacitance–voltage-based extracted set of parameters. Cells from each type of cancer cell line were suspended in a liquid media either individually or as mixtures with their normal counterparts. Empirically, normal cells were observed to exhibit higher dielectric constants when compared to cancer cells from the same tissue. Moreover, adding cancer cells to normal cells was observed to increase the capacitance of normal cells, and the extent of this increase varied with the type of tissue tested with the lung cells causing the greatest change. This shows that the cancer cells of different cell origin possess their own signature electrical parameters, especially when compared with their normal counterparts, and that cancer cell seems to affect normal cells in a different manner, depending upon the tissue type. It was also noticed that the cells (both cancer and normal) exhibited a higher dielectric value as per the following order (from least to most): breast, lung, and liver. The changes in electrical parameters from normal to cancer state were explained not only by the modification of its physiological and biochemical properties but also by the morphological changes. This approach paves the way for exploring unique electrical signatures of normal and their corresponding cancer cells to enable their detection and discrimination.

Leadless pacemaker implantation in young adults with vasovagal syncope and major cardioinhibitory component: About 2 cases

Vasovagal syncope is generally benign but may associated to pacing indication. We report two cases of vasovagal requiring pacemaker implantation. A leadless pacemaker was preferred to conventional pacing. Clinical cases: two women aged 24 and 16, were showing repetitive faintness. They presented prodromal symptoms, without triggering factor, that lead to collapse accompanied by convulsions or serious traumas. After a full neurological check-up and elimination of underlying cardiopathy, the diagnosis of vagal syncope with major cardioinhibitory component was made: for one through an implantable loop recorder with sinusal pauses of more than one minute, for the other with a positive tilt test and demonstration of a 18 seconds sinusal pause on a 72 h Holter ECG. The postural and the beta-blocker treatment being inefficient, pacing was decided. A Medtronic MICRA was implanted, via the right femoral vein, on the interventricular septum. Mean procedure time was 50 minutes. Micra was positioned at the first attempt in both patients with thresholds < 0.5 V. No complications were observed and both patients were treated in our outpatient clinic. No syncope occurred since then in both patients over a follow-up of 2 and 12 months without significant change in electrical parameters. Even if the DDDR pacing is to be favoured as first intention in this indication, the new leadless pacemakers show many advantages: no surgical approach, infections and haemorrhages decrease, displacement risk decrease, aesthetic keeping up with a same longevity to current simple room pacemakers. Thus, leadless pacemaker can be discussed for young patients with indication for pacing associated to vagal syncope. However, data is lacking in these patients, particularly concerning long-term follow-up.

Magnetic field of a ribbon busbar of finite length

Using the analytic method based on the Biot-Savart law for the electromagnetic field, the distribution of the magnetic field of a ribbon busbar of finite length has been determined. The Mathematica program was used to visualize the solutions obtained. This allowed quick field analysis after changes of geometrical or electrical parameters of systems under examination.

Effect of ageing on magnetic and electrical properties of Ti–substituted La-Sr manganites

The changes of structural, magnetic and electrical parameters of ceramic La0.8-xSr0.2+xMn1-xTixO3+γ (0.025 ≤ x ≤ 0.150) manganites during long-term storage at room temperature and after thermal cycling were investigated. The unit cell volume (V) of all manganites decreased over time. Most considerable decrease of V and broadening of X-ray diffraction lines width were observed in the samples with high quantity of titanium. During the storage period magnetization (σ) and Curie point (Tc) of manganites with relatively low Ti content decreased, while the compositions with high values of “x” exhibited some trend of σ and Tc increase. The resistance of the samples with x &lt; 0.100 increased over time. Fluctuations of magnetization of all thermal-aged samples were within the error of measurement, and Curie point of manganites with x = 0.150 showed the rise. From the data obtained it might be inferred that ageing phenomena in Ti-substituted manganites can be associated with oxidation processes, the transfer of Ti4+ to vacant sites in rare-earth sublattice and formation of microinhomogeneities.

On-Line Parameter Identification of an Induction Motor With Closed-Loop Speed Control Using the Least Square Method

The control system of induction motors is designed to achieve dynamic stability, allowing accurate tracking of flux and speed. However, changes in electrical parameters, due to temperature rise or saturation level, can lead to undesirable errors of speed and position, eventually resulting in instability. This paper presents two modes for parametric identification of the induction motor based on the least squares method: batch estimator and recursive estimator. The objective is to update the electrical parameters during operation when the motor is driven by a vector control system. A drawback related to the batch estimator is the need for high quantity of available memory to make the process of identification robust enough. The proposed algorithm allows the batch estimator to be viewed as a single matrix problem reducing the need for processing memory. The identification procedure is based on the stator currents measurement and stator fluxes estimation. Basically, both modes of identification will be analyzed. Experimental results are presented to demonstrate the theoretical approach.

Ischemic small intestine—in vivo versus ex vivo bioimpedance measurements

Objective: Bioimpedance has been used to investigate changes in electrical parameters during ischemia in various tissues. The small intestine is a multi-layered structure, with several distinct tissue types, and ischemia related changes occur at different times in the different intestinal layers. When investigating how the electrical properties in the small intestine is affected by ischemia, some researchers have used ex vivo models while others have used in vivo models. In this study, we compare ischemic time development of electrical parameters in ischemic in vivo versus ex vivo small intestine.Approach: Measurements were performed using a two-electrode setup, with a Solartron 1260/1294 impedance gain-phase analyser. Electrodes were placed on the surface of ischemic pig jejunum, applying a voltage and measuring the resulting electrical admittance. In each pig, 4 segments of the jejunum were made ischemic by clamping the mesenteric arteries and veins, resulting in a 30 cm central zone of warm ischemia and edema. The in vivo part of the experiment lasted 10 h, after which 3 pieces of perfused small intestine were resected, stored in Ringer-acetat at 38 °C, and measured during a 10 h ex vivo experiment.Main results and significance: We found significant differences (p < 0.0001) between the values of electric parameters when comparing the in vivo and ex vivo measurements as a function of ischemic time development. We also observed some similarities in the trends. In vivo, we measured an overall decrease in impedance during the duration of the experiment, probably as a result from the formation of edema. Ex vivo, the low frequency impedance increased initially for approximately 3 h before starting to decrease.

CLASSIFICATION OF PROTECTION DEVICES OF JAW CRUSHERS

A method of classification of jaw crushers protection devices was developed, based on the following classification criteria: crushing machine subsystem, recoverability of the protection device after operation and necessary setting parameters. Separation of protection devices by subsystems forms an additional level in hierarchical structure of technological process automated control system. At this level, subsystems monitoring operability of crusher with significant deviance of calculated parameters from their nominal value, i.e. in emergency situation are located. Classification of protective devices based on restorability, that is, by ability to restore their properties after restoring of design parameter value, and on parameters of protective devices of various subsystems is necessary to determine the method of protective devices design. Their specific features are also to be taken into account during their implementation. The following parameters were considered: force acting from the crusher jaw side; pressure that occurs in hydraulic system of protective device exposed to the action of a crusher jaw; the moment developed by a crusher drive; current value in the drive of the crusher - for electrical subsystem protective devices; temperature of the crusher motor; frequency range of current consumed by electric motor. The proposed classification improves accuracy of crusher’s condition diagnosis: in terms of direct evaluation, which is the most rapid, based on changes in electrical subsystem parameters; in terms of indirect evaluation, which is more accurate, based on change in crusher output parameters as a whole, with constant parameters of electrical subsystem. Joint use of direct and indirect evaluation of the crusher state increases accuracy and efficiency of crusher control, increasing accordingly reliability of crusher unit as a whole.

Adaptive Kalman Estimation of Phase Holdup of Water-Continuous Oil-Water Two-Phase Flow

Phase holdup measurement of the two-phase flow is of significance in industrial process. Accurate and real-time measurement of phase holdup is a critical problem requiring urgent solutions. Conductance sensors determine the flowparameters by detecting the change of electrical parameters. Kalman filter is widely applied in state estimation, and oil-water two-phase flow holdup measurement is considered as a state estimation problem in this paper. By using upstream and downstream measuring fluctuation information, an adaptive Kalman estimation model based on discrete cross-correlation with adaptive state transition matrix, and a serial estimation model based on unscented Kalman filter carrying out linear and nonlinear estimations successively are proposed combining with specific flow state. The proposed methods have been validated by online experiments, and the average error of phase holdup estimate is 1.5%.

The use of dynamic electro - cost model for the study of changes in economic and electrical parameters of the generating system

Formation of the cost of electricity in the local power generating systems of Microgrid should be based on dynamic models that properly take into account the fundamental nature of the dynamic power control system, and enable for flexible changes in economic parameters of the generating system. An urgent task is to create a dynamic mathematical model of the producer - consumer system of electricity, which should combine, on the one hand, the energy performance of the generating system, and on the other - economic indicators of macroeconomic closed system. The article describes an example of an isolated system consisting of a diesel generator and the consumer. The resulting model allows to investigate the impact of macro-economic parameters of an isolated system to change the value indicators of the economic system when changing the power level, given the presence of transients in the generator.

Simulation of a vibrating reed exciter for thickening different fabrics in weaving loom

A new weaving loom vibrating mechanism excited electromagnetically has been elaborated and presented in the article. The aim of the study has been to analyze the changes of electrical and dynamical parameters of vibrating system comprising the weaving loom with the reed forced to the vibrations by the special exciter. The magnetic field in the magnetic circuit of the exciter has been consisted of a steel core, the two steel pole pieces, permanent magnet and air gaps. In the air gaps of the magnetic circuit there have been arranged the serially connected coil segments, with a counter wound windings. It has been used the Nd-Fe-B permanent magnet. In an electrical circuit, which includes copper windings of the coil segments, alternating current flows, causing generation of the resultant electro-dynamic force exciting the motion of the coil segments along their axis. Using Finite Element Method a model of the exciter has been elaborated for calculation of changes in the resultant inductance of the exciter coils with the increasing the coils displacement against the stator and with increasing the current flowing in the coil windings. During analysis it has been used the axisymmetrical model, making the analysis simpler. The mesh of triangular finite elements has been created automatically by the commercial program FEMM. The appropriate boundary conditions, material parameters and extortion were introduced into the model. Based on the obtained results it has been assumed the constant value of coil inductance for the range of analyzed coil displacements, which have been smaller than 1 mm. Also the calculation model for the vibrating reed system has been elaborated and shown in the article. The electrical and dynamical parameters of the vibrating system have been simulated under conditions of thickening the fabrics of different thickness and supply with ac power. It has been analyzed the waveforms of the current in the exciter coils and their changes as the function of dynamic parameters of the created fabric. It has been also studied the influence of supply voltage and parameters of the created fabric for the peak values of current flowing in the exciter coils. It has been obtained the waveforms of the vibrational motion of the reed for various parameters of the created fabrics. It has been analyzed the reduction of the operating amplitude of the vibrational motion with respect to the start-up amplitude. It has been concluded, that the reduction of the operating amplitudes of the reed vibrating movement occurs together with the values of dynamic parameters of the thickened fabric. In extreme cases, for fabrics characterized by relatively high damping and significant stiffness it reaches 50%. It has been also noted, that during thickening the fabrics with typical dynamic parameters, the operating amplitude of the reed vibrating motion reaches 70 - 90% of the peak start-up amplitude. Also the peak values of flowing current have been observed during the start-up and during the operating movement of the reed in the extreme position of weaving loom. It also have been observed, that the peak value of the flowing current during the phase of operating vibratory motion of the reed in-creases with the stiffness and the mean value of current increases with the damping coefficient of thickened fabric. DOI: http://dx.doi.org/10.5755/j01.mech.22.5.13360

Accelerator-based electron beam technologies for modification of bipolar semiconductor devices

Radiation processing technologies for static and dynamic parameters modification of silicon bipolar semiconductor devices implemented. Devices of different classes with wide range of operating currents (from a few mA to tens kA) and voltages (from a few volts to 8 kV) were processed in large scale including power diodes and thyristors, high-frequency bipolar and IGBT transistors, fast recovery diodes, pulsed switching diodes, precise temperature- compensated Zener diodes (in general more than fifty 50 device types), produced by different enterprises. The necessary changes in electrical parameters and characteristics of devices caused by formation in the device structures of electrically active and stable in the operating temperature range sub-nanoscale recombination centres. Technologies implemented in the air with high efficiency and controllability, and are an alternative to diffusion doping of Au or Pt, γ-ray, proton and low-Z ion irradiation.