Longitudinal impedance measurements and simulations of a three-metal-strip kicker

A kicker is a critical component for beam injection and accumulation in circular particle accelerators. A ceramic slat kicker plated with a TiN conductive coating was applied in the Beijing Electron Positron Collider (BEPCII). However, the ceramic slat kicker has experienced several sudden malfunctions during the operation of the BEPCII in the past. With a reliable kicker structure, a three-metal-strip kicker can substitute the original ceramic slat kicker to maintain the operational stability of the BEPCII. A comparison of the numerical simulation was conducted for three kicker models, demonstrating the comprehensive advantage of the three-metal-strip kicker. Furthermore, impedance bench measurements were conducted on a prototype of a three-metal-strip kicker. The longitudinal beam-coupling impedance was measured using a vector network analyzer via the coaxial wire method. A satisfactory agreement was obtained between the numerical simulations and measurements. Based on the numerical simulation data, the loss factor was 0.01721 V/pC, and the effective impedance was 3.59 mΩ(σ=10 mm).The simulation of the heat deposition on each part of the kicker demonstrated that 84.4%of the parasitic loss of the beam was deposited on the metal strips, and the total heat deposition power on the kicker was between 113.3 and 131.5 W. The obtained heat deposition powers can be considered as a reference for establishing the cooling system.

Improvement Design of Biochip Towards High Stable Bioparticle Detection Utilizing Dielectrophoresis Impedance Measurement

Dielectrophoresis impedance measurement(DEPIM)is a powerful tool for bioparticle detection due to its advantages of high efficiency,label-free and low costs.However,the strong electric field may decrease the viability of the bioparticle,thus leading to instability of impedance measurement.A new design of biochip is presented with high stable bioparticle detection capabilities by using both negative dielectrophoresis(nDEP)and traveling wave dielectrophoresis(twDEP).In the biochip,a spiral electrode is arranged on the top of channel,while a detector is arranged on the bottom of the channel.The influence factors on the DEP force and twDEP force are investigated by using the basic principle of DEP,based on which,the relationship between Clausius-Mossotti(CM)factor and the frequency of electric field is obtained.The two-dimensional model of the biochip is built by using Comsol Multiphysics.Electric potential distribution,force distribution and particle trajectory in the channel are then obtained by using the simulation model.Finally,both the simulations and experiments are performed to demonstrate that the new biochip can enhance the detection efficiency and reduce the negative effects of electric field on the bioparticles.

Using the system function to analyze the performance of transducer's impedance measurement method

Prom investigation of the advantages and disadvantages of conventional tri-voltage method,a method for the measurement of the transmitting transducer＇s impedance was presented to solve the difficult problem of examining the consistency of the transmitting phased array on the single-mode excitation sea spot.In the method based on the system function, the circuit structure of tri-voltage method was used but new parameters were measured.The principle of the method was given first.Then when resistors with different nominal values were used in the circuit,the measured results for the impedance of transducers were reported.The results were compared with the higher precision impedance analyzer.Finally,the error analysis was performed according to the impedance formula and the equivalent circuit parameters were fitted.Under the condition of guaranteeing the sampling precision,by performance analyzing, the resistor value in series was chosen relatively smaller than the impedance of transducer,the measurement of impedance could achieve the same precision as the higher precision impedance analyzer.Finally,the least squares curve-fitting of measured curves indicated that the transducer equivalent electrical parameters could be extracted accurately and used to design the matching network.

In Situ Acquisition of Equivalent Circuit Parameters of Crystal Resonance during Copper Deposition and Dissolution in Acidic Solution by Electrochemical Quartz Crystal Impedance System

Electrochemical quartz crystal impedance system (EQCIS) which allows in situ dynamic quartz crystal impedance measurement in an electrochemical experiment was developed by combining an HP 4395A Network/Spectrum/Impedance analyzer with an EG&G M283 potentiostat. Equivalent circuit parameters of crystal resonance change significantly during electrodeposition and dissolution of copper in 0.1 mol/L H2SO4 aqueous solution in a cyclic potential sweep experiment, which is explained with an overall picture of mass loading, solution density and viscosity, etc..

Nucleation and Growth of Thallium on Thin Film Mercury Electrode: Voltammetric, Scanning Electron Microscopy, Chronoamperometric and Electrochemical Impedance Studies

Thallium is a heavy metal highly toxic to the biosphere. It can be determined by anodic stripping voltammetry after deposition on mercury film. The aim of this work is to study the conditions and mechanisms of deposition of Hg on glassy carbon electrode and Tl on Hg film by cyclic voltammetry, scanning electron microscopy, chronoamperometry and impedance techniques. The results showed a germination and growth of a 3D Hg phase on glassy carbon electrode. Similarly, the electrodeposition of Tl on Hg follows a 3D three-dimensional nucleation with diffusion controlled growth. The impedance measurements reveal an easier charge transfer on the Tl film.

Online Measurements of High-band Grid Impedance Using Variable Frequency Carrier Based PWM Schemes

Grid-connected power electronic devices, such asvoltage-source inverters (VSIs), are increasingly installed in thegrid for the utilization of renewable energy sources. Under highpenetration, the weak grid contains plentiful harmonics and complexgrid impedance values, which have deep impacts on systemstability as well as its control performance. Online impedancemeasurement is needed for impedance based adaptive controland analysis. This paper proposes a variable carrier frequencyPWM (VCFPWM) based online grid impedance measurementtechnology. This method broadens the available working rangein the high frequency band without increasing the low bandperturbations. Through good analysis and design of the carrierfrequency, the VCFPWM method injects sufficient harmonicenergy at specified high frequency points and guarantees lowTHDs at the same time. The detailed design considerations ofthe carrier frequency are clarified and the characteristics of theVCFPWM based excitations are analyzed in this paper. Finally,the simulation and experimental results based on a three-phasegrid-connected VSI are presented to verify the effectiveness ofthe proposed method.

Preparation and Characterization of La0.67–x Li3x TiO3 Solid-State Electrolyte Used for Electrochromic Mirrors

With the aim of producing all-solid-state electrochromic mirrors, La0.67–xLi3xTiO3 (LLTO) and the WO3 were prepared by electron beam deposition. The LLTO (with x = 0.11) powder was synthesized by thermally ball-grinding method and the Li+ ionic conductivity of the LLTO ceramic targets was found to be of ca. 3.25 × 10–3 S/cm. Using LLTO targets for e-beam evaporation, 300 nm-thick films with the Li+ ionic conductivity of 5.50 × 10–5 S/cm were deposited. Combining LLTO films with WO3/ITO and LiMn2O4 layers, all-solid-state electrochromic mirrors with a laminar structure of Al/LiMn2O4/LLTO/WO3/ITO were prepared. The reversible reflectance of the mirrors was well controlled by applying polarized potentials onto the ITO electrode. The obtained results suggest useful applications for electrochromic windows working as a smart reflectance mirror that can be used for auto rear-view mirrors.

Positive predictors for gastroesophageal reflux disease and the therapeutic response to proton-pump inhibitors

AIM: To identify objective and subjective predictors for the reliable diagnosis of gastroesophageal reflux disease (GERD) and the response to proton pump inhibitor (PPI) therapy.

Preparation of IrO_2+MnO_2 coating anodes and their application in NaClO production

To improve the durability as well as to reduce the cost of anodes, the IrO2＋MnO2 composite coating anodes for NaCIO production were prepared by thermal decomposition. Scanning electron microscopy （SEM）, energy dispersive X-ray spectroscopy （EDX）, and X-ray diffraction analysis （XRD） were carried out to investigate the morphologies, element distribution, and microstructure. The anodic polarization curves were employed to study the effect of sintering temperature on the Cl2 evolution reaction （CER） of the electrodes. The accelerated life tests （ALT） and electrochemical impedance spectroscopy measurement （EIS） were utilized to investigate the stability. The rules of NaCIO production were also studied by the static electrolysis experiment. The results indicate that sintering temperature has a significant influence on the CER properties as well as the ALT values of the electrodes. The electrode prepared at 400℃ has the best CER properties and the longest ALT value.

Measured Impedance and Threshold Value of Electrode Line Impedance Supervision Based Protection in HVDC Transmission System

At present,electrode line impedance supervision(ELIS)based protection is widely used to detect faults on grounding electrode lines,which are indispensable elements of high-voltage direct current(HVDC)systems.The existing theoretical analysis of measured impedance is based on lumped line model and the threshold value is generally set according to engineering experience,which have caused the dead zone problem and even accidents.Therefore,a study on measured impedance of ELIS-based protection and its threshold value selection method is carried out to solve this problem.In this study,the expressions of measured impedance under normal operation and fault conditions are deduced based on rigorous and accurate line model.Based on the expressions,the characteristics of the measured impedance are calculated and analyzed.With the characteristics of the measured impedance,the applicability of the protection with the traditional threshold value is further discussed and the distribution of the dead zone can be located.Then,the method to calculate the threshold value of ELIS-based protection is proposed.With a proper threshold value selected by the proposed method,the dead zone of ELIS-based protection is effectively eliminated,and the protection can identify all types of faults even with large transition resistances.Case studies on PSCAD/EMTDC have been conducted to verify the conclusion.

Improvement of admittance measurements for modeling of an ungrounded reactor/transformer winding

In this paper,a model of an ungrounded reactor winding is developed for transient voltage studies.The developed model is a black box model where the state-space model is developed using the directly measured admittance matrix of the reactor winding.Furthermore,an improved model is developed,where the accuracy of the admittance matrix measurement set in the low frequency band is obtained indirectly using an additional set of voltage ratio measurements.When the measured admittances are low,the accuracy of the diagonal admittance vectors in the low frequency band is low as well.However,the accuracy at low frequencies obtained using the indirect measurements is improved at nodes with the lowest admittances.In this paper,different approaches for indirect measurements are studied and the most accurate method is identified considering the physical structure of windings.

Investigations by electrochemical quartz crystal impedance system-electrodeposition of silver and polyaniline

An electrochemical quartz crystal impedance system (EQCIS) which allows rapid and simultaneous measurements of admittance spectra of piezoelectric quartz crystal resonance during electrochemical processes was developed by combining an HP 4395A Network/Spectrum/Impedance analyzer with an EG & G M283 potentiostat. Non-linear least square regression analyses of simultaneously acquired conductance and susceptance data were discussed in detail, giving that Rm, Cs, 1/Cm (or Lm) and of as estimation parameters is the best choice among various fitting routines. Equivalent electrical circuit parameters of quartz crystal resonance during electrodeposition of silver and polyaniline and electrochemical processes of the deposits were obtained and discussed according to changes in electrode mass, electrode surface roughness and film conductivity etc. The significant changes of motional resistance Rm and static capacitance C, observed in the silver case was believed to result mainly from changes in electrode surface roughness and the linear relationship between them was well explained by the following equation, Cs = Cq+ Ce = εqAq/ hq + εek2Rm/[he(ωρLηL]1/2.

Clinical experiment of exercise induced asthma and respiratory impedance assessed with impulse oscillometry to measure exercise response of asthmatics

Abstract Objective In order to investigate pathophysiology of exercise induced asthma (EIA), the impedance of the respiratory system was studied using impulse oscillometry (IOS). EIA is a temporary increase in airway resistance, which occurs after several minutes of strenuous exercise. Most asthmatics experience EIA. Patients and methods Respiratory impedance was measured with IOS (MasterScreen, Jaeger, Germany) in 14 healthy volunteers and 14 asthmatics as baseline value at first. The procedure of exercise challenge with an ergometer (Corival 300 Gould Co.) increased heart rate to 90% of predicted maximum values in 3-4 min and maintained for 6 min. After challenge, measurements with IOS were made immediately at 5 min intervals for 5 times. Results The maximal increase of respiratory impedance occurred at 5-10 min after exercise and the increment magnitude of peripheral resistance (99.6%) was more than that of central resistance (13.5%) in asthmatics. After challenge, R5Hz, R5Hz-R20Hz, Zrespir (total impedance), resonance frequency (Fres) and X5Hz from patients changed significantly. The increment value of R5Hz-R20Hz from asthmatics was≥0.032kpa/l·s -1 and the change ratio of X5Hz from 71.4% of asthmatics was ≥41% (2SD beyond the mean response of nonashmatics). Air trapping loop was expressed in V T Zrespir graph in 57.1% patients. All subjects underwent IOS measurement. Conclusion Exercise test can diagnose asthma and evaluate efficacy of treatment for bronchial asthma. Because the patients usually have shortness of breath after exercise challenge, the measurement with spirometry (FEV 1) may not be accurate. IOS is based on measurement of the relationship between an external pressure pulse applied to the respiratory system and the resulting respiratory airflow. The spectral ratio of the amplitude of the pressure wave signal to the resulting flow signal constitutes the impedance of the respiratory system, from which the resistance (R) and the reactance (X, including elastance and inertance) of respiratory system in the frequency range 5Hz to 35Hz can be calculated. Our data showed that the increment value of R5Hz-R20Hz was more sensitive than other indices for detecting exercise induced asthma. The bronchoconstriction took place in peripheral airway mainly after exercise. Because obstruction of small bronchi during expiration and impedance increased abruptly, air trapping loops were expressed in V T Zrespir graph after challenge in asthmatics. Fres is the frequency point where the absolute value of elastance equals to that of inertance. X5Hz reflects the condition of compliance of lungs. Fres shifted right and change ratio of X5Hz increased after exercise were relative to the compliance decrease of lungs. The airway response of exercise challenge may be assessed more accurately and more conveniently with IOS that did not require a maximal inspiration and forced expiration.

Evidence of a third kind of Johnscher’s like universal dielectric response

Polymer/metal composites(PMC)comprising of polyvinylidene fluoride/nanocrystalline nickel with varying volume fractions of nickel(fcon)prepared under cold press show an insulator to metal transition(IMT)at percolation threshold(f_(c)=f_(con)=0:27).The two kinds of generalized Johnscher’s universal dielectric response(UDR)laws on both sides of IMT hold good,while for the percolative sample,none of the two laws hold good.Neither the concept of dipolar relaxation nor anomalous low frequency dispersion stands valid for f_(c)=0:27,while a completely different,neutral and competing electrical behavior is observed over the entire range of frequencies.The emerged third kind of Johnscher’s like UDR for fc is observed and the relaxation law has been formulated as the ratio of imaginary and real parts of dielectric constant remains constant over the entire range of frequency starting from dc to any higher frequency.The value of the constant is attributed to depend on the PMC,the dielectric constant of the polymer,the differences of conductivity and fractions of the components of the PMC and also on their connectivity arising due to the difference of their process conditions.The emerged unique dielectric relaxation consists of multiple relaxations arising due to the combination of other relaxations(arising due to the two different types of species)present in the sample,f_(con)=0:27.This novel material may be suitable for certain specific applications in electrical and electronics engineering.

Physicochemical properties of proton-conducting SmNiO3 epitaxial films

Proton conducting SmNiO_(3)(SNO)thin films were grown on(001)LaAlO_(3)substrates for systematically investigating the proton transport properties.X-ray Diffraction and Atomic Force Microscopy studies reveal that the as-grown SNO thin films have good single crystallinity and smooth surface morphology.The electrical conductivity measurements in air indicate a peak at 473 K in the temperature dependence of the resistance of the SNO films,probably due to oxygen loss on heating.A Metal-Insulator-Transition occurs at 373 K for the films after annealing at 873 K in air.In a hydrogen atmosphere(3%H_(2)/97%N_(2)),an anomalous peak in the resistance is found at 685 K on the first heating cycle.Electrochemical Impedance Spectroscopy studies as a function of temperature indicate that the SNO films have a high ionic conductivity(0.030 S/cm at 773 K)in a hydrogen atmosphere.The activation energy for proton conductivity was determined to be 0.23 eV at 473-773 K and 0.37 eV at 773e973 K respectively.These findings demonstrate that SNO thin films have good proton conductivity and are good candidate electrolytes for low temperature proton-conducting Solid Oxide Fuel Cells.

Preliminary Research on Relationship Between Dielectric Property and Microstructure of Rabbit Liver

The dielectric properties in vitro present characteristic changes along with the alteration of metabolic activities, which can be detected from tissue micro- structure. The dielectric properties of tissues are closely related to its viability, but the relationship remains unclear to us. This study aims to specify the relationship between dielectric parameters and microstructure of living tissues and to try to explain the influence of tissue viability on dielectric properties. Nine rabbits were studied in this experiment. The impedance spectroscopy （10 Hz-1 MHz） and microstructure were determined at different time intervals （from 5 rain to 7 h） after samples were prepared. Some characteristic parameters were extracted to analyze the relationship between them. The inactivation process characterized by the mierostrueturs could be detected by means of dielectric parameters： the microstructures had no obvious change within 30 rain a.nd cell swelling caused by osmosis led to the decrease of extracellular ion concentration, resulting in the rise of lowfrequency impedance after 30 rain. The reduction of impedance was accompanied by the expanding intercellular area and irregular cell shape caused by the gradual destruction of cell membrane.The functions between alteration rate of intercellular area and Cole-Cole model parameters were also established. There is a strong correlative relationship between dielectric properties and microstructure. The dielectric spectrum can be a rapid and innocuous method to monitor the status of tissues. In the future, it may be of great help for clinical application, especially in transplantation.