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The double layer present at the interface of an electrode and an analyte causes electrode polarization (EP) in impedance spectroscopy, which hinders acquiring the actual impedance of biological samples at a lower frequency region. In this work, a novel carbon paste (CP) electrode material prepared by mixing the pencil graphite powder with transparent glue has been reported to reduce the EP by depositing its two coplanar electrodes on a chromatography paper substrate. Furthermore, two other devices having silver paste and pencil electrodes on the chromatography paper have been fabricated, analyzed for the EP, and compared with the CP electrode. The EP is quantified by fitting the impedance data to an equivalent electrical circuit having double layer capacitance as a constant phase element, and the CP electrode shows the lowest EP among the electrodes. The cyclic voltammetry analysis reveals blocking electrode property of the CP, which diminishes dc current flow at the electrode/electrolyte interface. Furthermore, the chromatography paper is found to increase the effective surface area of the deposited electrode by enhancing its surface roughness, which helps reduce the EP. [ABSTRACT FROM AUTHOR]

This research presents the design and fabrication of a semi-automatic paper petal compression machine with a pneumatic system to crease paper petals for making artificial flowers. The description comprises the procedures of defining operating characteristics for the machine, drawing its function diagram, designing the pneumatic circuit and the electrical circuit, calculating and choosing the dimensions of pneumatic components, and studying optimum paper petal compression conditions and appearances of creases on the paper petals. The machine can be used to compress the paper petals in four positions at the same time. The experimental materials were the paper of 55 and 65 gsm which was cut in the petal shape. The experiments were done by rolling 6, 8, 10, 12, 14, and 16 pieces of paper petals into hollow cylinders of which four rolls of those with the same number of paper petals were compressed simultaneously at the operating pressure of 0.6 MPa. The results showed that the machine could be used to compress the paper petals of 55 gsm to provide quite noticeable and consistent creases in the range of 6 to 14 pieces per roll, while the paper petals of 65 gsm were in the range of 6 to 12 pieces per roll. [ABSTRACT FROM AUTHOR]

This article presents a compact, low-cost, robust, and flexible test platform for determining the concentration of drugs in fluids. This device is based on a PVC foil card containing copper conductive foils in which disposable paper test strips are inserted. The paper test strips are overlaid with deposition of multiwalled carbon nanotubes (MWCNTs) acting as a sensing layer. When a paper test strip is inserted into the test card, the conductive path between two copper lines is established. A drop of test fluid on the sensing MWCNT layer changes the conductivity in a concentration-dependent manner, enabling calculation of the drug concentration after measurement of the electrical resistance at the copper terminals. An equivalent electrical circuit was also proposed to model the response of the fabricated sensor. It was shown that model parameters are dependent on the concentration of the cytostatic drug methotrexate. Additionally, the fabricated sensor demonstrated the ability to differentiate the same concentration of methotrexate and cyclophosphamide. The complete readout electronics and polynomial transfer function for calculating drug concentrations were also developed and are presented. [ABSTRACT FROM AUTHOR]

This paper discusses the effect of temperature on polarization and depolarization current measurements on paper oil insulation system. The influence of copper sulphide formed due to corrosive sulphur in mineral oil, on the changes in polarization and depolarization current at different temperatures are considered. A significant increase in the magnitude of polarization and depolarization currents due to deposits of copper sulphide on paper layers is observed. The conductivity of paper insulation increases significantly with increase in temperature. The increase in current is attributed to thermally active conducting particles of copper sulphide. The Debye model parameters of equivalent circuit under copper corrosion have been computed and a model for failure due to copper sulphide is explained using the data on polarization and depolarization currents. [ABSTRACT FROM PUBLISHER]

Paper-touchpad for the detection of Parkinson's tremor • Paper based flexible touchpad was fabricated. • The resistive touchpad works based on output electrical resistance. • The concept is further extended to developed flexible hand tremor detector. • A prototype was developed to detect the hand tremor for diagnosing neurological disorders such as Parkinson's diseases. A resistive touchpad was developed employing paper, pencil graphite, and polydimethylsiloxane (PDMS). A pair of flexible substrates with one side coated with conducting graphite and the other with insulating polymer, were assembled with the help of an intercalated polymer spacer having holes which, allowed the inner graphitic layers of the paper surfaces to come in contact with each other upon touching or pressing. An external electrical circuit was designed to detect the variations in the output electrical resistances. The resistive pad was further modified to develop a point-of-care-testing (POCT) device to detect the hand tremors associated with the neurological disorders such as Parkinson's disease. The proof-of-concept POCT pad showed variations in the electrical resistance due to the variation in contact area at the inner conductive layers of the paper surface when pressed with a pair of human fingers experiencing tremors. Simplified circuit-models have been discussed to explain the operating principles of the resistive pad and the POCT device. The response from the detection unit helped in evaluating the real time hand tremor levels of patients. The POCT prototype was able to detect the early to chronic stages and severity of tremor and thus is capable of detecting diverse neurological disorders. [ABSTRACT FROM AUTHOR]

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The analysis of dielectric response function obtained from the power transformer is a well-accepted technique in insulation diagnosis. A convenient way of analysing time-domain dielectric response φ(t) is the formulation of simple resistance -capacitance-based circuits like the conventional Debye model (CDM) or the modified Debye model (MDM) that are capable of modelling φ(t). However, available techniques do not guarantee unique branch parameters of such circuits for a given φ(t). In fact, the branch parameters are known to depend on the curve-fitting procedure opted during model formulation. This makes accuracy of CDM and MDM parameter-based diagnosis techniques less reliable. Furthermore, it seems logical to analyse the time-domain dielectric response of oil-paper insulation using a model containing time-varying parameters. In this study, a methodology is proposed using which such an insulation model (containing time-varying parameters) is formulated using timedomain insulation response. Related analysis presented suggests that the proposed model is immune to problems associated with available insulation models (containing time-invariant parameters). The performance of the proposed model in indicating insulation condition is tested on data obtained from several real-life power transformers. [ABSTRACT FROM AUTHOR]

In comparison with the AC and DC working voltages, the effect of switching impulse voltage on insulation is very different because of its fast-rising rate and large amplitude. This paper mainly focuses on the characteristics of PD in oil-impregnated paper insulation under switching impulse voltage. First, a robust experimental platform was set up including the impulse power source, test samples with uniform gas and oil gap, and the signal acquisition and processing system. PD characteristics in the air and oil gap are analyzed and compared involving the time-domain waveforms, the variation tendency of the average amplitude and numbers of PD pulses, the occurrence time and the instantaneous value of impulse corresponding to the first PD. Based on the dielectric barrier discharge (filament) theory, a parallel microcircuit model was established to explain the similarities and dissimilarities, and to evaluate the gap discharge intensity. The occurrence and development of PD under switching impulse voltage of typical oil-impregnated paper defect were studied systematically with simulation, experiments, and modeling. [ABSTRACT FROM AUTHOR]

The article focuses on several papers discussed at the 2013 Latin America Symposium on Circuits and Systems (LASCAS), held in Cuzco, Peru in February 2013. The papers presented at the symposium include "Fully Integrated Inductive Ring Oscillators Operating at VDD below 2kT/q" by M. Machado et al., "A fully Integrated Boost Converter For Thermoelectric Energy Harvesting" by H. Hernandez et al. and "A Biopotential Amplifier with Dynamic Capacitor Matching for Improved CMRR" by R. Abdullah et al.

This paper proposes a method for estimation of tanδ of cellulosic parts in oil-paper insulation from frequency domain spectroscopy based on equivalent circuit model of oil-paper insulation in real-life transformers. Existing literature shows that overall condition of oil-paper insulation in transformer can be assessed by conventional frequency domain spectroscopy. Also, the condition of oil can be separately and easily predicted through analyzing its dielectric properties by taking out the oil samples from transformer. However, it is quite difficult to assess the dielectric properties of cellulosic parts in oil-paper insulation as it cannot be directly accessed from outside for an operating transformer. Considering the aforesaid fact, this paper presents a segregated equivalent circuit model of composite oil-paper insulation that can separately estimate the tanδ profiles for oil as well as cellulosic parts. The tanδ profiles of cellulosic parts obtained from the equivalent circuit model have been validated experimentally. Results show that the tan? profile obtained from experimental result holds good agreement with that of the proposed model. [ABSTRACT FROM PUBLISHER]

The paper presents new diagnostic method applied to assess aging degree for paper-oil insulation used in professional electrical power device, primarily including medium and high power transformers. The described method is based on modified diagnostics using the recovery voltage effect occurring in dielectrics (RVM ? Recovery Voltage Methods). Modification of the RVM method applied so far, which is now used only to assess moistening degree for paper-oil insulation in power transformers, consists in a new parametric analysis of recovery voltage time characteristics. Simulation and experimental tests carried out in laboratory conditions for adequately prepared insulation samples have proven that the time-constant of recovery voltage decay (?R_MIN) is the most susceptible parameter as regards quantitative change in the function of aging of the examined insulation. This conclusion is also confirmed by statistical studies, in which a multi-parameter variance analysis method has been applied. An original equivalent circuit diagram of the insulation has been used to simulate aging degree of paper-oil insulation samples in numerical tests. The diagram is based on the Cole-Cole type dielectric response model. [ABSTRACT FROM AUTHOR]

Herein, we proposed the addition of an inkjet-printed conductive pattern to paper-based analytical devices (PADs) in order to expand their applications. An electric conductive pattern was easily, quickly, and inexpensively fabricated using a commercial inkjet printer. The addition of a printed electric element will enhance the applications of PADs without the loss of properties such as cost efficiency, disposability, and portability. In this study, we applied an inkjet-printed heater to a piece of paper and investigated its characteristics. The use of the heater as a valve, concentrator, and heat source for chemical reactions on PADs was investigated. Previously, these functions were difficult to realize with PADs. The inkjet-printed heater was used as a valve and concentrator through evaporation of the working fluid and solvent, and was also found to be useful for providing heat for chemical reactions. Thus, the combination of printed electric circuits and PADs has many potential applications. [ABSTRACT FROM AUTHOR]

Compared to conventional ac cables, the current rating of HVDC cable circuits is more complicated because the permissible current is not only limited by the operating temperature, but also by the electrical stress within the insulation. Therefore the IEC60287 current rating standard is considered insufficient for some HVDC applications because it fails to include the stress limitation. This paper presents an analytical methodology to calculate an electrical stress-limited rating for HVDC cables, which considers the maximum dielectric stress as the current limiting factor. This paper represents the first part of a project which has comprehensively reviewed cable rating calculations for mass impregnated HVDC cable systems. [ABSTRACT FROM PUBLISHER]

Samples of a dried composite oil-paper system were thermally aged in the laboratory under N2 in a sealed container and analysed using their dielectric response. The contributing loss processes were separated using an equivalent circuit model containing constant high frequency capacitances, dc-conductances, a dispersive capacitance, and a low frequency quasi-dc (q-dc) dispersion process as circuit elements. This low frequency dispersion in oil-paper samples is a bulk property of the system that is often mistaken for a dc conduction process when only the imaginary capacitance or ac-conductance is measured. The Dissado-Hill response function is proposed for the frequency dependence of the dispersive capacitance in the mid-frequency range rather than the Debye function because its cluster concepts correlate with the sample morphology of a matrix of oil-filled cavities. The quasi-dc dispersion is assigned to the transport of mobile charges between charge-clusters associated with locally connected oil filled cavities, which is a process that can be represented on a global scale by the form of hierarchical circuit system that leads to constant phase angle responses, and is here modelled by the Dissado-Hill q-dc function. It was found that the two dispersions moved together to higher frequency with thermal ageing of the composite material. The characteristic frequency common to the dispersions had an activation energy that decreased with thermal ageing, whereas their amplitude increased. This behavior is discussed in terms of possible changes to the oil-paper composite caused by the ageing process. [ABSTRACT FROM AUTHOR]

This study investigates the application of a Wheatstone bridge, specifically through the utilization of a meter bridge constructed on chart paper using pencil graphite. Employing the Wheatstone bridge principle, this study aims to achieve precise measurements of an unknown resistance. Results indicate an error margin between measured and calculated values of less than 10%, highlighting the efficiency and accuracy of this approach. The demonstrated effectiveness of the meter bridge serves as an educational resource, particularly beneficial for K-12 students, providing practical understanding and hands-on experience with the meter bridge concept. This research contributes to enhancing STEAM education by offering a tangible and accessible tool for teaching electrical circuit principles. [ABSTRACT FROM AUTHOR]

Printed electronics are a set of additive manufacturing methods for creating future flexible electronics on thin polymeric sheets. We proposed the toner-type, dry, page-printing of Ag–Ni composite conductive particles on flexible plastic sheets without pre-treatment. No chemical solvents are necessary to compose the inks of the electronic materials used for the toner-type printing, and no chemical treatment is required for the plastic film substrate surface. In addition, multilayer printing is simple when using toner printing because previously printed materials do not need to be resolved; furthermore, composing the thick films of the electronic materials is relatively simple. In this study, we fabricated an Ag–Ni composite toner to improve the fluidity of the toner particles compared to bare Ag particles. We successfully printed IC peripheral circuits at a resolution of 0.20 mm and demonstrated that the actual electrical circuit pattern can be formed using our method. [ABSTRACT FROM AUTHOR]

We demonstrate a novel method for controlling fluid flow in paper-based devices. The method delays fluid progress through a porous channel by diverting fluid into an absorbent pad-based shunt placed into contact with the channel. Parameters to control the delay include the length and the thickness of the shunt. Using this method, reproducible delays ranging from 3 to 20 min were achieved. A simple electrical circuit model was presented and used to predict the delays in a system. Results from the model showed good agreement with experimental observations. Finally, the shunts were used for the sequential delivery of fluids to a detection zone in a point-of-care compatible folding card device using biochemical reagents for the amplified detection of the malaria protein PfHRP2. [ABSTRACT FROM AUTHOR]

With the aim of preparing paper-based writing electronics, a kind of conductive pen was made with nano-silver ink as the conductive component and a rollerball pen as the writing implement. This was used to direct-write conductive patterns on Epson photo paper. In order to decrease the sintering temperature, pressure was introduced to enhance the driving forces for sintering. Compared with hot sintering without pressure, hot-pressure can effectively improve the conductivity of silver coatings, reduce the sintering time and thus improve productivity. Importantly, pressure can achieve a more uniform and denser microstructure, which increases the connection strength of the silver coating. At the optimum hot-pressure condition (sintering temperature 120 °C/sintering pressure 25 MPa/sintering time 15 min), a typical measured resistivity value was 1.43 × 10-7 Ω m, nine greater than that of bulk silver. This heat treatment process is compatible with paper and does not cause any damage to the paper substrates. Even after several thousand bending cycles, the resistivity values of writing tracks by hot-pressure sintering stay almost the same (from 1.43 × 10-7 to 1.57 × 10-7 Ω m). The stability and flexibility of the writing circuits are good, which demonstrates the promising future of writing electronics. [ABSTRACT FROM AUTHOR]

A method to extract the elements of the small-signal equivalent circuit and the noise parameters (NPs) of heterojunction bipolar transistors (HBTs) is presented. The extraction is done by simultaneous fitting of the measured S-parameters, noise figure (for a well-matched impedance), and NPs (estimated using the so-called F50 method). An additional error term, given by the root square sum of the differences between the NPs estimated from the F50 method and the NPs directly computed using the Hawkins model, is considered in order to avoid nonphysical results in the extraction of the intrinsic noise sources. To obtain the initial values of the equivalent-circuit elements, analytical expressions are applied under a number of bias conditions, namely, reverse bias, forward bias, and active bias. Experimental verification of the extraction of the equivalent-circuit elements and NPs of an HBT, up to 8 GHz, are presented, and the NPs are compared to those measured with an independent (tuner-based) method. The behavior of Fmin, extracted using the proposed method, as a function of the HBT collector current, is also presented. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1372–1379, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21649 [ABSTRACT FROM AUTHOR]

This paper describes a novel approach to fabricate paper-based electric circuits consisting of a paper matrix embedded with three-dimensional (3D) microchannels and liquid metal. Leveraging the high electric conductivity and good flowability of liquid metal, and metallophobic property of paper, it is possible to keep electric and mechanical functionality of the electric circuit even after a thousand cycles of deformation. Embedding liquid metal into paper matrix is a promising method to rapidly fabricate low-cost, disposable, and soft electric circuits for electronics. As a demonstration, we designed a programmable displacement transducer and applied it as variable resistors and pressure sensors. The unique metallophobic property, combined with softness, low cost and light weight, makes paper an attractive alternative to other materials in which liquid metal are currently embedded. [ABSTRACT FROM AUTHOR]

Supercapacitors (SCs) are an emerging energy storage technology with the ability to deliver sudden bursts of energy, leading to their growing adoption in various fields. This paper conducts a comprehensive review of SCs, focusing on their classification, energy storage mechanism, and distinctions from traditional capacitors to assess their suitability for different applications. To investigate the voltage response of SCs, the existing electrical equivalent circuits are further studied. The analysis is carried forward with the parameter of impedance, which has not so far been addressed. Impedance analysis is essential for a better understanding of SCs as capacitors work on alternating source of supply. The paper also highlights the applications of SCs in electric automobiles and charging stations, showcasing their advantages such as fast charging and higher power density compared to traditional capacitors. Additionally, other applications in areas like the military, medicine, and industry are discussed, demonstrating the versatility of SC technology. [ABSTRACT FROM AUTHOR]

The article announces the Best Paper Awards for papers published in the periodical in areas of electric circuits, systems and signal processing including the Armen H. Zemanian Best Paper Award to Michał Tadeusiewicz and others; and the Sydney R. Parker Best Paper Award to Fatema Tuz Jhohura and others.

This research paper presents a symmetrical current-tunable active-RC all-pass filter that uses an active BJT coupled with R and C. The circuit's symmetrical structure ensures that the differential signals are treated equally, resulting in improved performance. Furthermore, the filter's ability to adjust the frequency by bias current makes it suitable for a wide range of applications, such as improving phase properties and creating other types of filters. The simulation results obtained through the Pspice program show that the value of the operating frequency can be adjusted by bias current, which is the highlight of this research. The transfer function of the circuit shows a response of about 0 dB and -90° respectively, indicating that the circuit can change the phase of the input signal without changing its magnitude. This feature is particularly useful in signal processing applications where phase changes are required. In addition, the paper discusses how the operating frequency can be increased by decreasing the capacitor. The transfer function of the circuit analyzed shows that the operating frequency (f0) is inversely proportional to the product of the capacitors. Therefore, decreasing the value of C increases the operating frequency of the circuit. Monte Carlo analysis results are also presented for resistors, capacitors, and transistors with error values. This analysis helps determine the effect of errors on the output signal of the circuit. The results show that the output signal is sensitive to changes in the resistor values, which can affect the accuracy of the filter. Therefore, it is important to select high-quality resistors to ensure that the filter operates accurately. [ABSTRACT FROM AUTHOR]

The state of the oil-paper insulation is a key factor for assuring a reliable operation of power transformers. Recovery voltage measurement is one of the methods utilized to estimate the polarization spectrum. Analysis of the polarization spectrum is used to evaluate the condition of the insulation with respect to moisture content and aging. In this paper, the elements which represent a polarization process are determined from recovery voltage measurement test results by using a new method based on genetic algorithm. The method was successfully tested on a simple circuit and then applied to two power transformers located in hydropower plants. [ABSTRACT FROM AUTHOR]

This paper described the development of a small and low cost biosensor consisting of a smartphone-based electrochemical biosensor device and a paper-based biosensor. The device harvested power from the smartphone and transferred data through audio jack. We designed CMOS circuits including a power supply circuit, a potentiostat, and a ΔΣ modulator. The fabrication of a paper-based biosensor was simple: the three electrodes were directly drawn on chromatography paper using a carbon pencil. The paper-based biosensor was low cost, disposable, portable and friendly to the environment. The sensing system was designed to perform the chronoamperometry measurement, and the glucose concentration in a liquid specimen was detected. Results showed that the sensing system was capable of measuring the glucose concentration as precisely as expensive equipments. [ABSTRACT FROM AUTHOR]

A capacitive sensing technique based on sigma‐delta modulation is presented. This architecture creates multi‐frequency drive and sense signals with high SNR. It enables concurrent and simultaneous self‐capacitive touch, mutual‐capacitive touch and capacitive pen. [ABSTRACT FROM AUTHOR]

This special issue of the IEEE Journal of Solid-State Circuits is dedicated to papers taken from the best of the Analog, Data Converters, RF, Wireless, and Wireline Sessions at the IEEE International Solid-State Circuits Conference (ISSCC) in San Francisco, CA, USA, held in February 2017. The Guest Editors of this special issue would like to thank the presenters in these sessions at the conference for their high-quality presentations, which made the selection process difficult. We would also like to extend our appreciation to the selected authors for their timely and excellent submissions, and to the reviewers who helped ensure the papers met our high-quality levels. [ABSTRACT FROM AUTHOR]

Turbine systems equipped with doubly fed induction generation (DFIG) are becoming increasingly vital in wind power generation, with the reliability of the devices serving as a pillar in the industrial sector. Thermal stress and lifetime assessment are fundamental indicators in this regard. This paper primarily addresses the thermal stress and lifespan of power semiconductor devices utilized in a DFIG grid-side converter (GSC) and rotor-side converter (RSC). PLECS (Piecewise Linear Electrical Circuit Simulation) is employed to validate the electrical and thermal stress of the power devices. Additionally, Ansys Icepak, a finite element analysis (FEA) software, is utilized to confirm temperature fluctuations under various operations. The power consumption and junction temperature of the power devices in the GSC and RSC of a 2 MW DFIG are compared. It is evident that the most stressed power semiconductor is the IGBT for the GSC with a temperature swing of 3.4 °C, while the diode in the RSC is the most stressed with a temperature swing of 10.1 °C. This paper also presents a lifetime model to estimate the lifespan of the power device based on the annual wind profile. By considering the annual mission profile, we observe that the lifetime of the back-to-back power converter is limited by the diode of the RSC, whose B10 lifetime is calculated at 15 years. [ABSTRACT FROM AUTHOR]

A numerical model based on Radial Basis Function-generated Finite Differences (RBFFD) is developed for simulating the Global Electric Circuit (GEC) within the Earth's atmosphere, represented by a 3-D variable coefficient linear elliptic PDE in a sphericallyshaped volume 5 with the lower boundary being the Earth's topography and the upper boundary a sphere at 60 km. To our knowledge, this is (1) the first numerical model of the GEC to combine the Earth's topography with directly approximating the differential operators in 3-D space, and related to this (2) the first RBF-FD method to use irregular 3-D stencils for discretization to handle the topography. It benefits from the mesh-free 10 nature of RBF-FD, which is especially suitable for modeling high-dimensional problems with irregular boundaries. The RBF-FD elliptic solver proposed here makes no limiting assumptions on the spatial variability of the coefficients in the PDE (i.e. the conductivity profile), the right hand side forcing term of the PDE (i.e. distribution of current sources) or the geometry of the lower boundary. [ABSTRACT FROM AUTHOR]

This article presents a bibliography of the papers related to relay literature. The papers listed in this bibliography include references to the subjects of service restoration, testing and methods of calculation well as to the field of relaying. The references also include the title, author, publication information and a summary of the subject matter. Some of the entries in this bibliography are: "Symmetrical Components Estimation through Non-Recursive Newton-type Numerical Algorithm," "Signal Processing Module for Power System applications," "Variable-Window Algorithm for Ultra-High-Speed Distance Protection," "Wavelet-Based ANN Approach for Transmission Line Protection," and "Enhanced Transmission Line Protection Settings."

To study sweep frequency impedance (SFI) features of short-circuit (SC) faults easily, this paper proposes a broadband electric circuit model of a transformer winding and solves its three key problems. The first problem is the calculation of lumped-circuit parameters considering frequency-dependent complex anisotropic permeabilities (FDCAPs), which are caused by the physical characteristics, such as skin, proximity, and geometrical effects and anisotropic properties, of the transformer core and winding materials. The other issue is the establishment of the electric circuit model based on the SFI measurement connection mode, the transformer winding parameters, and a double-ladder network (DLN). Another issue is the construction of the state-space model of the electric circuit toward different SFI values to obtain all network branch voltages and currents. The accuracy of the proposed model is assessed by comparing its SFI signatures with those of the simulation model, without considering FDCAPs under healthy winding, and the corresponding physical transformer model during healthy winding and SC faults. It is observed that the SFI results of the proposed model are closer to the experimental measurements, and the model can be effectively used to study the SFI features of SC faults. Moreover, the impacts of different types of SC faults on the SFI data are concluded in this paper. [ABSTRACT FROM AUTHOR]

The multi-terminal modular multi-level converter-based high voltage direct current (MMC-HVDC) grid with short circuit protection equipment (SCPE) is so complex that it is difficult to estimate its fault current and analyze the performance of SCPE by conventional time-domain numerical calculation method, it meets three big obstacles. This paper has made significant progress in overcoming these obstacles. 1). By applying the modern electrical circuit theory, a systematic formulation of the differential equation set for fault current calculation is developed to avoid a lot of complex and cumbersome matrix manual calculations. 2). A novel Y-Delta transformation in the s-domain is proposed to develop an eliminating virtual node approach for a complex MMC-HVDC grid, including the ring, radial, and hybrid topologies. 3). It is difficult to solve the equivalent circuit of MMC-HVDC grid with SCPE since SCPE is a timevariable-nonlinear circuit. A canonical voltage source model of SCPE is established to transform the time-variable-nonlinear circuit into a piecewise linear circuit. Based on the three significant progresses, a DC fault current fast-computing method of MMC-HVDC grid with SCPE is put forward to deal with all kinds of MMC-HVDC grids with several kinds of SCPEs. Then, the performance of several kinds of SCPE is analyzed and compared by this method. Consequently, the proposed DC fault current fast-computing method is a new powerful tool to estimate the fault current of MMC-HVDC grid and analyze the performance of SCPE. [ABSTRACT FROM AUTHOR]

Purpose: This paper presents the design, development, and performance analysis of a Two-Degree-of-Freedom Vibration-Based Electromagnetic Energy Harvester (TDOF VBEEH). The purpose is to enhance power output and widen the operational frequency band of the harvester. In the literature, various techniques such as mechanical amplification, resonance tuning, and nonlinear oscillations etc., have been explored. The proposed TDOF VBEEH incorporates a mechanical amplifier in series with a traditional Single-Degree-of-Freedom (SDOF) VBEEH. Methods: The paper derives an analytical expression for the average power output of the TDOF VBEEH based on the principles established by Tang and Zuo. The effects of mass ratio, electrical damping ratio, and tuning ratio on the power output and effective operational frequency band of TDOF VBEEH have been studied to provide design guidelines for TDOF VBEEH. Also, the experimental analysis is conducted to examine the effects of a purely resistive load and mass ratio on the average harvested power of the TDOF VBEEH. The study utilizes a specially designed setup for TDOF VBEEH. Furthermore, by employing the method of surface plots and contour diagrams, the global optimum values of power output for the TDOF VBEEH under various electrical damping ratios and normalized excitation frequencies have been determined. Results: The results demonstrate that the appropriate selection of mass ratio, tuning ratio, and electrical damping ratio can enhance the power output and widen the effective operational frequency band of the TDOF VBEEH. Notably, the maximum harvested power is achieved when the electrical circuit connected to the harvester has a resistive load of approximately 1500 Ω, which aligns with the internal resistance of the copper coil. The results show that the increased power output is attainable over a widened operational excitation frequency band compared to the traditional Single-Degree-of-Freedom (SDOF) VBEEH. From the comparison of the experimental and analytical results, it is seen that the TDOF VBEEH performs better than the SDOF VBEEH when the parameters are properly chosen. Conclusion: These findings highlight the superior performance and potential of TDOF VBEEHs over SDOF VBEEHs, emphasizing the importance of parameter selection in maximizing power output and widening the operational frequency band. Also, the findings offer valuable design guidelines for selecting system parameters when developing TDOF VBEEHs to power small electronic devices. [ABSTRACT FROM AUTHOR]

This paper presents a simulation model for a system equipped with thermoelectric elements, considering the impact of independent thermal contact resistances on each side of the module. An analytical model was constructed, taking into account the asymmetry of thermal resistances between the generator/cooler and the respective heat source/heat sink. A comparative analysis of thermoelectric device operating indicators such as conducted heat, efficiency, and the electricity/cooling power produced was performed. The selection of electrical current in the circuit was analysed based on the maximization of power or efficiency. This paper discusses deviations from ideal conditions, specifically the absence of thermal resistance between the heat source/sink and the thermoelectric junction. The model accurately simulates the operating conditions of the thermoelectric system with a low computational cost. The results indicate that the total thermal resistance, rather than its location, predominantly affects the operation of the thermoelectric generator. However, in cooling operations, the influence of thermal resistance significantly depends on the cooling power demand and temperature. [ABSTRACT FROM AUTHOR]

The paper [[9]] presents an absolutely new circuit based on the implementation of quaternion-based devices by using analog electronic circuits. The study by Dieste-Velasco gives a contribution in the area of the CAD design of electronic analog circuits and therefore the integration of AI tools with of classical electronic devices' CAD design modules. Analog circuits are essential in everyday life and in electrical engineering. [Extracted from the article]

Constantly emerging new technologies have a significant impact on higher education - both positive and negative. E-assignments and online exams are commonly adopted at universities. The randomization of exam questions can be a way to prevent cheating and plagiarism. However, it can also bring the heavy working load to teachers, especially for teaching in big classes. The module leader would like to share an automatic randomization method for exam question design, which makes the assessment procedure transparent, flexible, and most importantly reproduceable. The method is based on Python language and its modules for scientific computing, and it can cover the assignment design in the modules, such as programming language, electric circuits, control systems, signal processing, mechatronics, robotics, etc. [ABSTRACT FROM AUTHOR]

Many students who enroll in a first course in linear algebra major in STEM disciplines other than mathematics. Teachers who serve such students may find it difficult to provide authentic problems from these broader areas that ignite students' interest in linear algebra. In this paper, we highlight an interdisciplinary learning activity that engages students in using linear systems of equations to model the behavior of practical electric circuits. This exercise fits nicely into standard introductory linear algebra curricula and is designed to excite students majoring in engineering, physics, or applied mathematics. We also include references to a collection of open-access resources to support instructors who want to use this material in project-based, flipped-learning, inquiry-oriented, or independent-study environments. [ABSTRACT FROM AUTHOR]