Two-terminal Method Research Articles

Photoelectrochemical Three-Dimensional Fabrication of Conductive Polymers Using Multi-Photon Absorption Process

Micro-nano 3D printing of conductive polymers is a technology developed by our research group for the first time in the world. Many monomers of conductive polymers are liquid state at normal pressure, but when polymerized, the product becomes an infusible and insoluble solid state, so three-dimensional structures can be obtained. Pyrrole undergoes polymerization through oxidation to become polypyrrole, and in this research, the photo-electrochemical oxidation reaction is achieved by multi-photon absorption sensitization. The multi-photon absorption reactions have extremely high spatial selectivity and can produce fine three-dimensional structures of conductive polymers. Extremely high electrical conductivity of up to 410 S/cm for polypyrrole (PPy) and up to 3500 S/cm for poly-3,4-ethylenedioxy-thiophene (PEDOT) were achieved using this method. The following two factors are thought to have contributed to these results. The extremely strong electromagnetic field of the femtosecond laser light source assists in the orientation of the polymer chain. Since a perfluoro-alkylsulfonic acid polymer (Nafion®) is used as the three-dimensional support, sulfonic acid ions serve as dopants and contribute to carrier generation. In this study, the effects of the laser scanning direction and method during modeling were discussed for appropriate evaluation of electrical conductivity. The electrical conductivity of the polypyrrole line shaped product obtained by the improved method was evaluated using a two-terminal method. As a representative result, the current-voltage characteristics are shown in Figure 1. The electrical conductivity obtained under the conditions of incident laser intensity of 2.2 mW, focus movement pitch of 0.005 μm, and waiting time at focus position of 0.1 seconds was 1203 S/cm. This value was a significant improvement over the value of 410 S/cm obtained using our previous method. The scanning method of the laser focus was changed to improve polypyrrole deposition on the lower surface of the Nafion sheet. It is thought that this effect resulted in higher conductivity than before. Figure 1

Electrochemical Properties of Co and Yb Doped BaZrO3 and Its Application to PCFC Cathodes

Protonic ceramic fuel cells (PCFC) are expected to have high power density and high energy efficiency because they can operate at 500-700°C and do not dilute the fuel. BaZrO3 doped with Yb is a candidate electrolyte for PCFC because it has high proton conductivity and chemical stability, does not react with Ni in the anode to form complex oxides, and can be manufactured industrially [1]. Many researchers have been exploring the cathode, but a material with higher activity is needed to improve the power density and efficiency. In this study, we investigated the electrochemical and PCFC cathodic properties of BaZr0.875-x Yb0.125Co x O3-δ (x=0.0-0.75), which is a Yb-doped BaZrO3 electrolyte with Co added to provide electronic conductivity.To clarify the electrochemical properties of BaZr0.875-x Yb0.125Co x O3-δ, the electrical conductivity was measured by the two-terminal AC method and the proton concentration was evaluated by TGA. The Co valence was confirmed by XPS and the coefficient of thermal expansion was evaluated by XRD. The electrical conductivity was found to increase with increasing Co content. The TGA results showed that the proton concentration decreased with Co addition, and increased with Co addition above 0.375. XPS results indicate that Co was mainly tetravalent below x=0.375, but at x=0.5, Co was both tetravalent and trivalent. The increase in proton concentration can be attributed to the increase in oxide ion vacancies due to compensation of trivalent Co. The coefficient of thermal expansion was found to be 9.8×10-6/K at x=0.5, which is close to that of BaZr0.8Yb0.2O3-δ, a candidate electrolyte for PCFC.The anode-supported PCFCs using BaZr0.875-x Yb0.125Co x O3-δ as cathode were constructed and power density was investigated, with the highest power output (545 mWcm-2 at 600°C) obtained at x=0.5. Further DRT analysis of the cell impedance showed that the electrode impedance of the anode-supported PCFC could be separated into five component. The isotope effect of the impedance was investigated by replacing the anode gas from H2O-H2 to D2O-D2, and the isotope effect was observed in the two components on the high frequency under OCV, indicating that it is attributable to the anodic reaction. On the other hand, no isotope effects were observed in the three high-frequency components under OCV, but isotope effects were observed in the highest-frequency component under bias (0.6 V). This component is considered to be the component attributed to the water vapor formation reaction and was found to have the highest resistance among the impedance components of the cathode. Acknowledgment This paper is based on results obtained from a project, (JPNP20003), commissioned by the New Energy and Industrial Technology Development Organization (NEDO).[1] T. Kuroha, Y. Niina, M. Shudo, G. Sakai, N.Matsunaga, T. Goto, K. Yamauchi, Y. Mikami, and Y. Okuyama, Journal of power sources, 506 (2021) 230134.

Analysis of Two-Terminal Hybrid Connection Method for Reducing Armature MMF Space Harmonics of Six-Phase Electric Machine

Analysis of Two-Terminal Hybrid Connection Method for Reducing Armature MMF Space Harmonics of Six-Phase Electric Machine

A two-terminal fault location method for gas switch prefire in linear transformer driver.

Large-scale linear transformer drivers (LTDs) are composed of numerous high-power gas switches, and switch prefire is a frequent operational fault. To detect and locate the faulty switch accurately and efficiently, a two-terminal location method is proposed. A B-dot sensor is integrated on the gas switch's shell to collect the discharging signal. All the B-dot sensors are connected in parallel through cables of equal length. The fault position can be determined by the time delay of the signals at the two terminals. A diode is inserted between the B-dot sensor's coil and the cable core to ensure low-loss transmission of the signal. Two methods are applied in fault location, including time-of-arrival (TOA) and time reversal (TR). For the TOA method, an energy criterion and a phase criterion are applied and compared. The accuracy of the energy criterion is greatly influenced by the signal-to-noise ratio, while the phase criterion requires a reasonable estimate of the actual delay to account for the impact of phase periodicity. The TR method based on a precise simulation model is established, which demonstrates high precision in location. The TR method has been tested and validated on a single stage LTD module. Moreover, the location method for double switches prefire is discussed theoretically. The method proposed in this paper will be helpful to improve the efficiency of the commissioning, operation, and maintenance of the large-scale LTD devices.

Bioaccessibility of novel antihypertensive short-chain peptides in goat milk using the INFOGEST static digestion model by effect-directed assays.

Short-chain peptides (SCPs, 2-4 amino acids) offer potential health benefits. A customized workflow was designed to screen SCPs in goat milk during INFOGEST digestion in vitro and 186 SCPs were preliminarily identified. Based on a two-terminal position numbering method and genetic algorithm combined with a support vector machine, 22 SCPs with predicted IC50 values less than 10μM were obtained using a quantitative structure-activity relationship (QSAR) model with satisfactory fitting and predictive capacity (R2, RMSE, Q2, and R2pre of 0.93, 0.27, 0.71, and 0.65, respectively). Four novel antihypertensive SCPs were confirmed by testing in vitro and molecular docking analysis, and their quantification results (0.06 to 1.53mg L-1) suggested distinct metabolic fates. This study facilitated the discovery of unknown potential food-derived antihypertensive peptides and the understanding of bioaccessible peptides during digestion.

A Two-Terminal Directional Protection Method for HVDC Transmission Lines of Current Fault Component Based on Improved VMD-Hilbert Transform

The traveling wave protection of high voltage direct current (HVDC) transmission lines is susceptible to the influence of transition resistance. As a backup protection, current differential protection has absolute selectivity, but usually requires an increase in delay to avoid misoperation caused by distributed capacitance on the line, resulting in a longer action time. Based on this, a two-terminal directional protection method for HVDC transmission lines is proposed based on Sparrow Search Algorithm (SSA)-Variational Mode Decomposition (VMD) and Hilbert phase difference. On the basis of analyzing the directional characteristics of the current fault component at both ends of the rectifier and inverter sides under different faults, SSA is first used to optimize the parameters of VMD. The residual components representing the direction of the current fault component at both ends are extracted through VMD, and then the Hilbert phase difference of the residual components at both ends is calculated to identify faults inside and outside the line area. In addition, fault pole selection can be achieved based on the ratio of the sum of multi-band Hilbert energy of single-terminal voltage fault components at the positive and negative poles. Simulation experiments have shown that the proposed protection scheme can quickly and effectively identify fault and has good tolerance to transition resistance and noise interference.

Fault Location Method of Multi-Terminal Transmission Line Based on Fault Branch Judgment Matrix

Aiming at the difficulty of fault location of multi-source transmission lines, this paper proposes a fault location method for multi-terminal transmission lines based on a fault branch judgment matrix. The fault traveling wave signal is decomposed by Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN), and the IMFs sensitive components that can characterize the fault characteristics of the target signals are selected by constructing a correlation-rearrangement entropy function. The arrival time of fault signals at the endpoint has been accurately calibrated by combining them with the Teager Energy Operator (TEO). To eliminate the influence of wave velocity and fault time on the location results, this paper proposes a two-terminal location method based on the line mode component to improve the location accuracy. On this basis, combined with the fault branch judgment matrix, the accurate location of multi-terminal transmission line faults is realized. This method has been shown to have high accuracy in detecting traveling wave heads, accurately judging fault branches, and producing a small error in fault location results. Compared with the existing multi-terminal transmission line fault location algorithm, it has obvious advantages and meets the needs of actual working conditions.

A novel line parameter adaptive phasor domain fault location method for double-circuit transmission lines

• Accurate phasor domain fault location for double-circuit transmission line. • Fault location without acquiring information of line parameters. • Uniqueness and convergence of the fault location equation solution. Phasor domain methods had been commonly used in power transmission line fault location. To improve the accuracy and line parameter adaptive ability of phasor domain fault location, this paper studies a two-terminal phasor domain line parameter adaptive fault location method. First, this paper analyses the convergence issue of original multi-dimensional non-linear fault location equations. Then, by regarding the four complexes consist of fault distance and line parameters as the new unknowns and thereby supplementing a constraint equation about the new unknowns, a quadratic fault location equation set is reconstructed. Furthermore, it is mathematically proven that the four new unknowns are all within the first quadrant. Therefore, the elements in the Jacobian matrix of the reconstructed equation set are all proven to be of symbolic invariance within the solution space. Thus, by using Newton-Raphson method and setting the initial iteration value of the four unknowns to any complexes within the first quadrant, the iteration solution of the reconstructed equation set will converge to the true solution. Finally, electro-magnetic fault simulations are used to evaluate the proposed method. The test results demonstrate that the proposed method is able to guarantee fault location accuracy under different circumstances without knowing line parameters.

Effects of Y2O3 doping on the phase composition, chemical diffusion coefficient and electrochemical properties of CaHfO3 proton conductor

In order to further understand the effect of Y2O3 doping on the electrical conductivity of CaHf1−xYxO3−δ, which was prepared by conventional solid-state reaction. The electrical conductivity of CaHf1−xYxO3−δ was measured by two-terminal AC method in an oxygen-rich atmosphere, hydrogen-rich atmosphere and water vapor-rich atmosphere at the temperature between 973 and 1373 K. The test results show that the conductivity of CaHf1−xYxO3−δ first increases and then decreases with x from 0.08 to 0.20, and its total conductivity and conductivity activation energy are 3.88 × 10−7 to 5.34 × 10−5S/m and 0.76–0.92eV respectively. Combined with the test results of the H/D isotope effect, it is found that protons are the main conductive carriers in the three different atmosphere at temperatures range of 973–1173 K. In addition, in the temperatures range of 1273–1373 K, the positive holes are the main conductive carriers in the oxygen rich atmosphere, and the vacancies participates in the conductive process as the main conductive carriers in the water vapor rich atmosphere. The chemical diffusion coefficients of CaHf1−xYxO3−δ is 3.9 × 10−6 to 2.4 × 10−5 cm2/s in the temperature range of 973–1373 K. According to the test results of electromotive force, the theoretical electromotive force is consistent with the measured electromotive force. The proton transfer number of CaHf1−xYxO3−δ exceeded 97% in hydrogen atmosphere at temperatures from 973 to 1173 K. In sum, these findings of CaHf1−xYxO3−δ can be used as alternative materials for hydrogen sensor electrolytes.

Research on the Electrochemical Properties of Al2−x Zn x O3−α

To understand the electrochemical properties of the Al2O3 based proton conductor in more detail, a solid-state electrolyte Zn-doped Al2O3 was successfully prepared using the solid-state reaction method at the temperatures of 1873 K for 10 h. The phase structure and microscopic morphology of these materials are thoroughly investigated. The structural analysis results revealed that the electrolyte has a pure perovskite phase structure. The crystal grains are relatively uniform, the ceramic material is dense, and the relative density is greater than 97 percent, according to microscopic morphology analysis. The electrical conductivity of the specimen was measured using the two-terminal AC method to clarify the electrochemical properties of Zn-doped Al2O3. The H/D isotope effect of electrical conductivity was studied, and it was discovered that protons are the dominant charge carrier at temperatures ranging from 1073 to 1473 K in hydrogen-rich atmospheres. The electrochemical impedance spectroscopy test showed that in the temperature range of 1073K–1473 K, the conductivity of the sample increases with the increase of temperature, and the electrochemical performance of the sample is the best when the doping amount is x = 0.012. The conductance activation energy () is in the range of 1.01–1.62 eV in hydrogen-rich atmospheres. From the point of view of electromotive force measurement, the theoretical (computational) electrical potential matches the measured potential very well. In a hydrogen-rich atmosphere of 1073–1473 K, the proton mobility of Al2−x Zn x O3−α exceeds 0.90. In this work, we proved that Al2−x Zn x O3−α sample is a proton conductor.

Dopamine-Sensing Characteristics and Mechanism by Using N2/O2 Annealing in Pt/Ti/n-Si Structure

Dopamine detection by using N2/O2 annealing in a Pt/Ti/n-Si structure is investigated for the first time. To achieve repeatable and stable dopamine detection, a Pt membrane is annealed at elevated temperatures of 500 to 700 °C. N2/O2 gas ambient is used to optimize the membrane. The Pt membrane with thicknesses from 5 to 2 nm is optimized. Novel Pt/Ti/n-Si Schottky contact in a metal–electrolyte–membrane–silicon (MEMS) structure detects dopamine with a low concentration of 1 pM. The Pt membrane with N2 ambient annealing shows the lowest concentration of dopamine sensing with a small volume of 10 µL, acceptable stability, and repeatability. Scan rate-dependent dopamine concentration sensing is also investigated in the two-terminal measurement method. This study is useful for the early diagnosis of Parkinson’s disease in the near future.

Fault location in overhead transmission line: A novel non-contact measurement approach for traveling wave-based scheme

Traveling wave fault location methods have gained considerable growth over the years, with the anticipation that power systems will be accurate and reliable everywhere. But the performance of classical traveling wave methods has focused only on traditional current transformer measurement in the literature till date. Therefore, in this paper, an innovative non-contact measurement of traveling wave formulation is proposed to achieve accurate fault location and time of arrival detection on a two-terminal overhead transmission line, since power cable naturally generates magnetic and electrical fields in the surrounding atmosphere. The proposed method solitary depends on the first two and successive time differences between the incident and reflective wave from the fault point of the transmission line. Thus, the proposed scheme does not depend on current transformer measurement that stimulates the accuracy and reliability of the conventional traveling wave fault location method. To ensure an accurate time of arrival waves detection, we exploit the magnetic field sensor array on each tower to measure the quality of current traveling waves generated on the transmission line and locate the transient disturbances as a result of a short circuit. By analyzing the line energization, a comprehensive fault analysis on a 500-kV line was simulated with PSCAD/MATLAB toolbox compared to the two-terminal classical method. The sensitivity analysis demonstrated that the proposed method is much accurate and reliable to be deployed and cost-effective, making it highly useful and efficient in comparison to the classical two terminals traveling wave method with an average error of 0.014%. The effectiveness of the proposed method was verified by laboratory experimental setup.

Partial discharge location of power cables based on an improved single-terminal method

The precise location of partial discharge (PD) in power cables is of great significance to ensure the stable operation of the power grid. Therefore, aiming at the problem of the PD location accuracy is the affected by the uncertainty of the wave velocity, an improved single-terminal method is used to estimate the PD location of power cables. In the proposed method, the wave velocity and arrival time difference of the PD signal are modified, so that it has a higher location accuracy and better robustness. Meanwhile, in order to improve the location accuracy of the PD location method in a noisy environment, the denoising algorithm of parameterless adaptive threshold empirical wavelet transform (PATEWT) is proposed in the paper. Compared with the traditional single-terminal method and two-terminal method, the proposed algorithm has a good denoising performance. Finally, simulations are provided to verify the effectiveness and feasibility of the proposed method.

Precise Traveling Wave-Based Transmission Line Fault Location Method Using Single-Ended Data

In this article, an accurate single-ended traveling wave-based fault location method is proposed for transmission lines with the inputs as the first three arrival times of traveling wave wavefronts and wave velocity of the line. In the calculation process, two fault distances are obtained considering the fault in the first or second half segment of the line by using the first (incident) and second (reflected) wavefronts. The third wavefront is then used to determine the faulted half segment and thereby select the correct fault distance out of the two. The technique is economical, and it does not require communication. The proposed technique is verified on a 400 kV, 50 Hz, 150 km two-terminal line using EMTDC simulations with a realistic line model. The performance of the method is evaluated for different fault locations, fault inception angles, and fault resistances. The test results obtained by the proposed method are compared with a practically proven two-terminal communication-based method and are found to be accurate.

Preparation and Electrochemical Properties of CaZr1-xScxO3-α

To develop a CaZrO3 -based, high-temperature proton conductor with high conductivity and resistance to the reduced atmosphere, we used Sc as a substitute for In as the dopant in CaZrO3. The electrical conductivity of CaZr1-xScxO3-α (x = 0.06, 0.12, 0.18, and 0.24) specimens was measured using the two-terminal ac method in an oxygen-rich atmosphere, hydrogen-rich atmosphere, and water vapor-rich atmosphere, at temperatures ranging from 573 K to 1473 K. The electrical conductivity of the CaZr1-xScxO3-α samples first increased and then decreased with the increase in amount of Sc2O3 doping, and it increased with an increase in temperature. The results of the H/D isotope effect measurement indicated that in the three different atmospheres, at temperatures from 573 K to 1273 K, protons are the dominant charge carrier. From the measurement of electromotive force, the theoretical (calculated) and the measured electromotive forces coincided. The proton mobility of CaZr1-xScxO3-α exceeded 90% in the hydrogen-rich atmosphere at temperatures from 573 K to 1273 K. At higher temperatures of 1373 K to 1473 K, positive holes were the dominant charge carrier in the oxygen-rich atmosphere, whereas the dominant charge carrier was vacancies in the hydrogen-rich atmosphere. These results agree with our previous studies.

Improvement of Water Resistance of a Proton Conducting Phosphate Glass Electrolyte By Addition of ZnO or CaO

Introduction CsH2PO4 (CHP) has been studied as a solid electrolyte for an intermediate-temperature fuel cell. It shows relatively high proton conductivity (10–2 Scm-1) in the intermediate temperature (100–300℃) range. However, humidification is necessary to maintain the crystal structure of CHP, and water resistance is extremely low. We reported that proton conducting glasses (CHP-PO4) made from CHP and phosphoric acid shows high proton conductivity and excellent water resistance compared with CHP under dry N2. However, the water resistance of the phosphate glasses needs to be improved for application to solid electrolytes. Metal oxides such as CaO and ZnO are often added for improving the water resistance of glass. Thus, in this study, we attempted to further improve the water resistance by adding the above metal oxide to CHP-PO4. The effect on proton conductivity was also evaluated by AC impedance measurements. Experimental CHP was synthesized according to the literature1. A phosphate glass electrolyte was prepared by mixing CHP and 85 wt% H3PO4 at a molar ratio of 1: 1 and heating at 500 °C for 5 min, then raising the temperature to 900 °C for 15 min. The obtained melt was spread out on a copper plate heated at 180 °C, and quenched to obtain a phosphate glass electrolyte. Ca or Zn containing glasses (abbreviated as CHP-x(CaO or ZnO)-PO4) were prepared as follows: CHP, H3PO4 and ZnO or CaO were mixed in Cs : (Zn or Ca) molar ratios of 1: x and melted and quenched under the same conditions as mentioned above. Raman spectra were measured using NRS3100 (JASCO Co. Ltd.). The proton conductivity of the electrolytes was measured by an AC two-terminal method under dry nitrogen using an impedance analyzer (Yokogawa, HP-4192A). The water resistance test was conducted by the following method: The sample was immersed in 200 mL of ultrapure water with stirring at 100 rpm, and the amount of eluted hydrogen ions per unit surface area of the sample was determined with a pH meter (CUSTOM Co. Ltd, IWC-5). Results and discussion The results of the water resistance test of phosphate glass electrolytes are shown in Fig. 1. It was revealed that increase in the ZnO or CaO ratio in the samples results in the improvement of the water resistance. The proton conductivities of the samples containing Zn or Ca were lowered to 10–3–10–4 S cm–1. Raman spectroscopic analysis of the phosphate glass revealed that the peak derived from ν(PO2)syn of the phosphate glass in CHP-x(CaO or ZnO)-PO4 shifted to the higher frequency by about 10 cm-1, which is attributable to the shorter phosphate chain. The present result suggested that the metal ions cross-linked phosphate chains and contribute the improvement of water resistance for the electrolytes. Reference 1. Qing et al., Electrochim. Acta, 169, 219–226, (2015). Figure 1

Estimation of Overhead Transmission Line Fault Distance Using Unsynchronized Two-Terminal Method

This paper presents the estimation of transmission line fault distance using unsynchronized two-terminal method. In operation, high or extra-high overhead voltage transmission lines can be interrupted. The disturbance can come from internal or external interference, which is permanent or temporary. For permanent interference, the network operator must visit the location of the disturbance in order to fix it. Because the transmission line is very long, while it takes quick time to find out the location of the disturbance so that it can be repaired immediately, then a method is needed to find out the location of the disturbance. This research proposes a method for determining the location of faults based on voltage and current data at the time of interference from both ends of the transmission line. The interference voltage and current data need not be synchronized. The use of this data makes this method very simple and easy to use. However, the accuracy of the estimation results can still be relied upon. In this study, a simulation was carried out on a two-end transmission line. The transmission line has a phase disturbance to the ground. The noise resistance applied in the simulation is 0 ohms, 10 ohms, 50 ohms, and 100 ohms. The results showed that the highest estimated error was 0.3%, which indicates that this method has a high degree of accuracy.

Synthesis and Electrical Properties of Composite Films Comprising Polymer Particles and Carbon Nanotubes

In the present study, composite films were synthesized from composite polymer particles prepared with multi-wall carbon nanotubes (MWCNTs) by in situ polymerization. Because one of the advantages of MWCNTs compared to other preparation methods is high electrical conductivity, the electrical properties of the composite films were evaluated by the direct current two-terminal method. As a result, the composite film prepared by MWCNTs had conductive paths and showed higher conductivity even at lower mass fraction of MWCNTs compared with the previous works to keep transparency. This method was shown to decrease the mass fractions of MWCNTs and increase the transparency of the composite films.

Locating Faults on Untransposed, Meshed Transmission Networks Using a Limited Number of Synchrophasor Measurements

The method of symmetrical components is not effective for fault location in the case of untransposed lines, due to potential couplings between the sequence circuits. This paper proposes a non-iterative algorithm in the phase-coordinates for wide-area fault location on untransposed transmission networks. In doing so, first, an improved two-terminal method is suggested to accurately locate faults on untransposed lines. Next, an algorithm is proposed to infer voltage and current phasors at the faulted line ends without direct measurements, by taking advantage of the data provided by phasor measurement units (PMUs). Accordingly, the adverse effect of close instrument transformers transients on the estimation accuracy is minimized. Being highly nonlinear in terms of fault distance and impedance, the fault equations are derived and made linear in this paper by defining six suitable auxiliary variables. The resulting system of equations is solved using the least-squares method to obtain three-phase voltages and currents at the faulted line ends. A main feature of the proposed algorithm is that it only requires a limited number of current and voltage synchrophasors. An additional advantage of the proposed algorithm is that the faulted line is not required to be known a-priori. The proposed algorithm is validated using extensive simulation studies on the New England 39-bus test system, accounting for different fault locations, types and resistances.

The Resistance Measurement Method of the Conducting Textiles

The report describes the technique to measure the resistance of some novel conducting threads. All of the measurements were performed in the EMC lab at SP Technical Research Institute of Sweden, Boras. The conducting threads were received from Ms. Azadeh Soroudi of the University of Boras. The conducting additive used for the threads was Carbon Black. The resistance was measured using two different methods: The two-terminal measurement method and the four-terminal measurement method. A result from the comparison of the two methods was that the two terminal measurement method provided more information than the fourterminal method. There seemed to be no advantage to use the four terminal method at all, for the resistance range studied.