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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]

High-temperature superconducting (HTS) coils are generally operated in a closed-loop persistent current mode, which is crucial for ensuring long-term stability and minimizing heat generation in various applications. However, factors such as joint resistance, flux creep, and losses due to external fields can lead to accelerated decay of the coil's current, making it challenging to achieve an effective persistent current mode. To gain insight into the current decay characteristics of HTS coils, we built a finite element method based model coupled with a lumped parameter electric circuit model. The model is initially verified against the experiment of an inductive magnetized HTS coil subject to a magnetic field perpendicular to the tape surface. The results indicate that the proposed model is highly effective in predicting the current decay behavior of this magnetized HTS coil and is able to provide high accuracy. With the help of this model, we have experimentally and numerically studied the behavior of a current-carrying closed-loop HTS coil subject to external alternating fields. The HTS coil is charged by a DC power supply and then shorted using a thermally-controlled persistent current switch. The current decay behavior of the HTS coil is examined under various scenarios. The simulation results show excellent agreement with experimental data, further validating the effectiveness and versatility of the modeling strategy. The influence of both local and global screening currents on the current decay performance of the closed-loop HTS coils has been investigated. For every case examined, rapid demagnetization occurred in the initial cycle of the applied alternating field. Furthermore, the current decay rate demonstrated a slight dependence on the frequency of the applied fields. Additionally, the resulting resistance has been thoroughly characterized. These insights contribute to the knowledge of the behavior and performance of closed-loop HTS coils, facilitating their practical application. [ABSTRACT FROM AUTHOR]

Non-Hermitian Hamiltonians effectively describing the physics of open systems have become an important tool in various physical platforms, such as photonics, mechanical systems, and electric circuits. The study of non-Hermitian states in electric circuits is developing rapidly recently and forming the field of topoelectrical circuits. Here, we report on the theoretical realization of a higher-order exceptional points (EPs) topological circuit induced by gain and loss. It is shown that, by tuning the value of the positive and negative resistors in the circuit, EPs can collide and merge leading to higher-order singularities. We observe the different energy-difference conserving dynamics near the EPs and the enhanced sensitivity at higher-order EPs. Our results show a way to get higher sensitivity in a non-Hermitian electrical circuit. [ABSTRACT FROM AUTHOR]

Nitrogen fixation, production of NO and NO2 from N2 and O2 in air, has been investigated with transient spark self-pulsing DC discharges. NO production is boosted by the addition of capacitors and an inductor to the electrical circuit which drives the discharge. The quantity of NO produced per joule of electrical input energy is doubled, though the quantity of NO2 produced drops. The yield of NO is also increased because the modified circuit enables higher discharge currents to be used. NO concentrations as high as 2000 ppm were obtained with input energy densities of around 300 J per liter of input gas, whilst NO2 concentrations were around 150 ppm. This simple modification of the driving circuit may have potential for optimizing the plasma chemistry with other input gas mixtures and for scaling up nitrogen fixation from air. [ABSTRACT FROM AUTHOR]

Flux pumps provide a promising solution for contactless charging of high-temperature superconducting (HTS) coils, eliminating the need for bulk current leads and reducing the heat burden for the cryogenic system. Characterizing the nonlinear effects of an HTS coil charged by a flux pump and understanding the dynamics of the charging process is essential for promoting the practical application of flux pumps. Numerical models provide a fast and cost-effective way of achieving this. In this study, we propose a methodology for coupling HTS coil and flux pump models using an electrical circuit, resulting in reduced computation costs. We validate the effectiveness of our approach against the experimental results of an HTS coil charged by a dynamo-type flux pump. Specifically, we obtain the voltage produced by the HTS dynamo using a 3D model based on the minimum electromagnetic entropy production method and apply this voltage to the load HTS coil using a T − A formulation finite-element method model coupled via an electrical circuit. The simulated charging current shows good agreement with experimental observations, validating our modeling strategy. The results demonstrate that the flux flow state in the HTS coil is the primary factor limiting the charging performance of the HTS dynamo as the charging current approaches the coil's critical current. Furthermore, based on the simulation, we demonstrate that, when using flux pumps, it is advisable to leave a margin between the operating current and the critical current of the coil. Overall, our approach has the potential to be applied to HTS coils charged by any device. [ABSTRACT FROM AUTHOR]

The non-Hermitian systems with the non-Hermitian skin effect (NHSE) are very sensitive to the imposed boundary conditions and lattice sizes, which lead to size-dependent non-Hermitian skin effects. Here, we report the experimental observation of NHSE with different boundary conditions and different lattice sizes in the unidirectional hopping model based on a circuit platform. The circuit admittance spectra and corresponding eigenstates are very sensitive to the presence of the boundary. Meanwhile, our experimental results show how the lattice sizes and boundary terms together affect the strength of NHSE. Therefore, our electric circuit provides a good platform to observe size-dependent boundary effects in non-Hermitian systems. [ABSTRACT FROM AUTHOR]

Underwater electrical wire explosion (UEWE) is an efficient source of underwater shock waves (SWs). In order to efficiently simulate the interaction between the UEWE SW and structures, a coupled model that includes the electric circuit, the exploding wire and the surrounding water is established based on user-subroutines provided by the commercial explicit dynamics software ANSYS AUTODYN. The modeling starts from room temperature by using the tabular wide-range metal equation of state (EOS) and conductivity data. Experimental validation is performed with copper wires exploded by a μ s-timescale pulsed discharge. The numerical results show satisfactory consistency with experiments in terms of the current and voltage waveforms, the wire expansion trajectory, the evolution of SW front, the interaction between SW and electrodes and the SW pressure profiles. The main discrepancy lies in the SW amplitude that is ∼20% higher in the calculation and the possible reasons are discussed in detail. Based on this approach and with proper modifications to the metal EOS and conductivity data, the interaction between UEWE SWs and structures can be efficiently modeled in 2D and 3D for practical applications. [ABSTRACT FROM AUTHOR]

In this paper the development of a high-power pulsed LED line light and its use to apply particle image velocimetry (PIV) during wave impact measurements are described. An electrical circuit that generates high-current pulses is designed and built, which is used to overdrive a number of commercially available LEDs. The limit for this overdrive-capacity is determined as function of pulse duration for various commercial available LEDs. Two systems of cylindrical convex lenses are designed to act as a collimator and reduce divergence of the LED bundle and the resulting light sheet properties (maximum light intensity and sheet thickness) are investigated. An array of LEDs of 60 cm length (referred to as the LED line light) is designed and manufactured. For the two lens systems, the LED line light provides proper light sheet conditions to illuminate measurement regions in the order of either 0.3 × 0.3 m2, or 1 × 1 m2, at a sufficiently constant light sheet thickness of 5 mm. The application of the LED line light is demonstrated by quantifying the instantaneous flow field of a wave impacting on a blunt object in a wave flume. PIV measurements are conducted at an acquisition rate of 25 frame pairs per second, quantifying maximum flow velocities in the order of 1.0 m s−1 at a LED pulse width of 200 μs. The system, consisting of the LED line light, a CMOS camera and open source PIV processing software provides the possibility to perform 2D planar PIV measurements for a fraction of the costs of a commercially available laser based PIV system. [ABSTRACT FROM AUTHOR]

Understanding simple electric DC circuits often represents a great challenge to many students in lower secondary schools. As a result, students' knowledge of this subject is often dominated by alternative conceptions, even after instruction. One of the reasons for these learning difficulties is the intangibility of key physical quantities and concepts of electric circuits such as the electric potential or the electric current. A potentially effective way of making circuits more accessible to students in introductory electricity lessons represents the use of analogies or models. However, as a brief review shows, there is no single analogy or model that is ideally suited to foster an understanding of all key aspects of simple DC circuits. In order to address this issue and help learners develop a mental model of circuits, a new analogical simulation of simple electric circuits was developed. The simulation is suited for use in combination with the bike chain and the air pressure analogy and aims to support students' development of a qualitative understanding of potential difference and current in circuits as well as a treatment of circuits as a connected system. Teachers and students can access the 3D simulation free of charge using a modern browser via www.marblemodel.com. [ABSTRACT FROM AUTHOR]

Knots are fascinating topological structures that have been observed in various contexts, ranging from micro-worlds to macro-systems, and are conjectured to play a fundamental role in their respective fields. In order to characterize their physical properties, some topological invariants have been introduced, such as unknotting number, bridge number, Jones polynomial and so on. While these invariants have been proven to theoretically describe the topological properties of knots, they have remained unexplored experimentally because of the difficulty associated with control. Herein, we report the creation of isolated electrical knots based on discrete distributions of impedances in electric circuits and observation of the unknotting number for the first time. Furthermore, DNA structure transitions under the action of enzymes were studied experimentally using electrical circuits, and the topological equivalence of DNA double strands was demonstrated. As the first experiment on the creation of electrical knots in real space, our work opens up the exciting possibility of exploring topological properties of DNA and some molecular strands using electric circuits. [ABSTRACT FROM AUTHOR]

Resistor networks are practical electric circuits and provide meaningful models to represent natural or artificial conductive structures. They can also be used to demonstrate how, in physics, general properties can be derived elegantly by combining general principles with symmetry properties. Here, this typical approach of physics is illustrated in the case of two-point resistances in the 2 × n globe network. It is a particular case of resistor networks on a sphere, where the n nodes of an equatorial frame of n identical resistors are connected by equal resistors to two axial poles. Recurrence relations are obtained using only Kirchhoff's laws and Kennelly's theorem. When complementing with relations derived using van Steenwijk's method, explicit relations are obtained for all two-point resistances to any order n. Such analytical exact results are useful to test the results of numerical or integral methods. This complete treatment of the 2 × n globe network can be used to illustrate for students the efficient ways of physics to derive analytical results and understand their origin. [ABSTRACT FROM AUTHOR]

Neural probes are in vivo brain-invasive devices that record and manipulate neural circuits using electricity, light, or drugs. The capability to shine distinct wavelengths and control their respective output locations for activation or deactivation of specific groups of neurons is desirable but remains unachieved. Here, we discuss our probe's capability to deliver two independently controllable wavelengths (450 and 655 nm) in the location(s) of interest using nanophotonic directional couplers and ring resonators. These nanophotonics are scalable to dozens of outputs without significantly increasing the device's lateral dimensions. Furthermore, they are entirely passive and thus do not require electrical input that results in heat generation. Besides, we integrate a high number of electrodes for a simultaneous neural activity readout. Thus, we overcome the challenges associated with multicolor illumination for neural devices by exploiting the capability of miniaturizable, passive probes to deliver two different frequencies in several areas of interest. These devices open the path towards investigating the in vivo electrical signal propagation under the individual or simultaneous activation or inhibition of distinct brain regions. [ABSTRACT FROM AUTHOR]

The structure design of micro cantilever beams(MCBs), which has a significant effect on MCBs' controllable actuation range, is usually restricted by the establishment of the inner electric circuit. This paper proposes the design of a micro electro-controllable twisting cantilever beam (METCB). The architecture and the fabrication diagram of the proposed METCB are presented before its features are theoretically and experimentally validated. In detail, the analytical validation includes a sequence of two models: electro-thermal and thermo-mechanical. Through these two models, the thermal distribution along the METCB and the deformation brought by the thermal distribution are investigated, respectively. On the basis of the design and equations, the METCB samples have been manufactured using a planar deposition technique with an e-beam evaporator. Two in-site experiments are then conducted to sequentially figure out the upper voltage limit of the inner electric circuit and the maximum temperature limit of the METCB. Finally, another experiment is carried out to explore the relation between the applied voltage and the relative twisting angle of the METCB sample. The theoretical prediction and the observed experiment result both prove the feasibility of the proposed METCB and its electro-controllable twisting ability. [ABSTRACT FROM AUTHOR]

Efficient conversion of the microwave energy into an atmospheric-pressure argon plasma in a microwave plasma sheet source (MPSS) operating at 2.45 GHz in ambient air is the subject of this work. The MPSSs, capable of providing an atmospheric pressure plasma in the shape of a narrow sheet are an innovative technology for variety of surface treatments with no impact on the environment. The existing designs of the MPSS exhibit unsatisfactory efficiency of the conversion of microwave energy produced by the microwave source into the microwave plasma (about 80%), which hinders implementation of the MPSSs in the industry. In this paper, after an analytical approach based on the equivalent electrical circuit method we proposed an optimization of the design of MPSS in terms of the microwave energy conversion efficiency. The MPSS design improvement consisted in reducing the electrical impedance in the input plane of the MPSS by introducing a capacitive diaphragm into the MPSS transmission line, which compensated the inductive character of the plasma sheet. The experimental measurement of the electrodynamic characteristics of the MPSS with diaphragm showed that using the diaphragm significantly decreased the microwave power losses due to the microwave reflection from about (20–30)% to a level of several percent. This substantially increased the MPSS energy conversion efficiency up to about 97%, 93% and 87% for incident powers PI of 500 W, 750 W and 1000 W, respectively. The electrodynamic characteristics of the MPSS appeared a very convenient tool for determining the conditions of maximum efficiency of conversion of the microwave energy into the microwave plasma. The electrodynamic characteristics were measured at argon flow rate of 20 Nl min−1. The analysis of the calculated input impedances of the MPSSs with and without diaphragm, based on the equivalent electrical circuits of both MPSSs confirmed that the change of the character of the input reactance of the MPSS from inductive to capacitive after introducing the diaphragm is the cause of the increase in the MPSS energy conversion efficiency. The MPSSs having the energy conversion efficiency such high as presented in this paper appears to be attractive innovative technology for economic use in industrial applications. [ABSTRACT FROM AUTHOR]

We report on the quantitative experimental illustration of elementary optomechanics within the classical regime. All measurements are performed in a commercial dilution refrigerator on a mesoscopic drumhead aluminium resonator strongly coupled to a microwave cavity, using only strict single-tone schemes. Sideband asymmetry is reported using in-cavity microwave pumping, along with noise squashing and back-action effects. Results presented in this paper are analysed within the simple classical electric circuit theory, emphasizing the analogous nature of classical features with respect to their usual quantum description. The agreement with theory is obtained with no fitting parameters. Besides, based on those results a simple method is proposed for the accurate measurement of the ratio between microwave internal losses and external coupling. [ABSTRACT FROM AUTHOR]

We propose a reverse-space nonlocal nonlinear self-dual network equation under special symmetry reduction, which may have potential applications in electric circuits. Nonlocal infinitely many conservation laws are constructed based on its Lax pair. Nonlocal discrete generalized (m, N – m)-fold Darboux transformation is extended and applied to solve this system. As an application of the method, we obtain multi-soliton solutions in zero seed background via the nonlocal discrete N-fold Darboux transformation and rational solutions from nonzero-seed background via the nonlocal discrete generalized (1, N – 1)-fold Darboux transformation, respectively. By using the asymptotic and graphic analysis, structures of one-, two-, three- and four-soliton solutions are shown and discussed graphically. We find that single component field in this nonlocal system displays unstable soliton structure whereas the combined potential terms exhibit stable soliton structures. It is shown that the soliton structures are quite different between discrete local and nonlocal systems. Results given in this paper may be helpful for understanding the electrical signals propagation. [ABSTRACT FROM AUTHOR]

Higher-order topological insulators have recently witnessed rapid progress in various fields ranging from condensed matter physics to electric circuits. A well-known higher-order state is the second-order topological insulator in three dimensions with gapless states localized on the hinges. A natural question in the context of nonlinearity is whether solitons can exist on the hinges in a second-order topological insulator. Here we theoretically demonstrate the existence of stable solitons localized on the hinges of a second-order topological insulator in three dimensions when nonlinearity is involved. By means of systematic numerical study, we find that the soliton has strong localization in real space and propagates along the hinge unidirectionally without changing its shape. We further construct an electric network to simulate the second-order topological insulator. When a nonlinear inductor is appropriately involved, we find that the system can support a bright soliton for the voltage distribution demonstrated by stable time evolution of a voltage pulse. [ABSTRACT FROM AUTHOR]

Topologically protected gapless edge states are phases of quantum matter which behave as massless Dirac fermions, immunizing against disorders and continuous perturbations. Recently, a new class of topological insulators (TIs) with topological corner states have been theoretically predicted in electric systems, and experimentally realized in two-dimensional (2D) mechanical and electromagnetic systems, electrical circuits, optical and sonic crystals, and elastic phononic plates. Here, we demonstrate a pseudospin-valley-coupled phononic TI, which simultaneously exhibits gapped edge states and topological corner states. Pseudospin-orbit coupling edge states and valley-polarized edge state are respectively induced by the lattice deformation and the symmetry breaking. When both of them coexist, these topological edge states will be greatly gapped and the topological corner state emerges. Under direct field measurements, the robust edge propagation behaving as an elastic waveguide and the topological corner mode working as a robust localized resonance are experimentally confirmed. The pseudospin-valley coupling in our phononic TIs can be well-controlled which provides a reconfigurable platform for the multiple edge and corner states, and exhibits well applications in the topological elastic energy recovery and the highly sensitive sensing. [ABSTRACT FROM AUTHOR]

Research indicates that troubleshooting activities that require students to reflect on pre-prepared erroneous examples, i.e. erroneous solutions to problems that correspond to common naďve ideas, impact their learning positively. These include asking students to diagnose erroneous examples; in other words, detect the conceptual errors and then explain why these errors are wrong. One of the major challenges is to determine the best ways to support student learning with troubleshooting activities. One suggestion involves contrasting erroneous examples with worked examples through a step-by-step demonstration of how to solve a problem. Here, a new troubleshooting activity designed to prompt students to learn more effectively from erroneous examples is described and assessed. The worked examples only constitute one part of the rubric, and students are required to both diagnose erroneous examples and then score them. Six 8th grade classes from three schools (two classes each from a different school taught by the same teacher) completed a pre-test/intervention/post-test after finishing a unit in simple electric circuits. In the intervention, in each school, one class was randomly assigned to the new activity (45 students) and the other class to the traditional troubleshooting activity with worked examples without rubrics (46 students). The findings suggest that the new activity enabled more students to learn from the erroneous examples than the traditional activity, regardless of whether the students' naďve ideas resembled the ones committed in the erroneous examples, and confirm the effectiveness of the new activity in 8th graders studying simple electric circuits. In a companion study by the first author (under review), the findings confirmed the effectiveness of the new activity in 10th graders studying geometric optics. Taken together, the findings of both studies may suggest that regardless of grade level or topic, the potential of learning from troubleshooting activities can be exploited effectively by implementing scoring erroneous examples along with a rubric portraying worked examples. [ABSTRACT FROM AUTHOR]

In this work three examples of textbook circuits (resistor-capacitor, resistor-inductor and resistor-inductor-capacitor) have been modeled by employing the Euler method for the approximate solution of differential equations using algorithms implemented in the Python programming language. The aim of this work was to demonstrate how simple, yet highly effective, algorithms can be neatly implemented in one of the currently most popular programming languages for scientific applications. At the same time, the visualization of the results allows for a detailed introduction to the properties of the circuits most frequently commented on in all the relevant textbooks. Our code, as provided to the reader, includes detailed comments, and can easily be modified to model other similar systems. Instructions on how to prepare tasks for students have been also provided. [ABSTRACT FROM AUTHOR]

Motivated by the concept of evolution, we surveyed the values of electric current feasible for the electric eel by reconfiguring the series-parallel combination of its biological cells called electroplaques. In particular, using a simple algebraic method, we found out the best series-parallel combination with which the eel can generate the maximum current in water, which is approximately 4.8 times the actual electric current produced by the eel. With the perspective of electric current alone, there may be selective pressure towards eels generating higher current if a new environment favors them. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) quadrupole topological insulators, featured by topologically protected 0D corner modes, have recently attracted tremendous interest in condensed matter and materials physics. Herein, we construct a specific electric circuit made of capacitors and inductors forming a 2D Kekulé hexagonal lattice for quadrupole topological phase and corner modes. Trivial–nontrivial topological phase transition can be controlled by varying capacitance in the circuit, so that distinct topological edge states appear in 1D ribbons and corner states emerge in 0D flakes. We explore the field strength distribution and two-point impedance with respect to excitation frequency, and reveal that the topological corner resonance is robust against size of the LC network and randomness of the capacitors/inductors, a great benefit for experimental detection. Our results enrich the family of designer topoelectrical circuit as a flexible and tunable platform to achieve exotic quantum phases, which may have potential for future telecommunications, signal processing and quantum computing. [ABSTRACT FROM AUTHOR]

A mathematical model of a high-sensitivity pressure sensor with a novel electrical circuit utilizing a piezosensitive transistor differential amplifier with negative feedback loop is presented. Circuits utilizing differential transistor amplifiers based on vertical n-p-n and lateral p-n-p transistors are analyzed and optimized for sensitivity to pressure and stability of output signal in operating temperature range. Parameters of fabrication process necessary for modeling of I–V characteristics of transistors are discussed. The results of the model are sufficiently close to the experimental data. [ABSTRACT FROM AUTHOR]

The idea of replacing traditional silicon-based electronic components with the ones assembled by organic molecules to further scale down the electric circuits has been attracting extensive research focuses. Among the molecularly assembled components, the design of molecular logic gates with simple structure and high Boolean computing speed remains a great challenge. Here, by using the state-of-the-art nonequilibrium Green's function theory in conjugation with first-principles method, the spin transport properties of single-molecule junctions comprised of two serially connected transition metal dibenzotetraaza[14]annulenes (TM(DBTAA), TM = Fe, Co) sandwiched between two single-walled carbon nanotube electrodes are theoretically investigated. The numerical results show a close dependence of the spin-resolved current-voltage characteristics on spin configurations between the left and right molecular kernels and the kind of TM atom in TM(DBTAA) molecule. By taking advantage of spin degree of freedom of electrons, NOR or XNOR Boolean logic gates can be realized in Fe(DBTAA) and Co(DBTAA) junctions depending on the definitions of input and output signals. This work proposes a new kind of molecular logic gates and hence is helpful for further miniaturization of the electric circuits. [ABSTRACT FROM AUTHOR]

One may be perplexed about the voltage across an inductor, since sometimes it is −LdI/dt, but more commonly it is LdI/dt. We explain why this is so, and point out that in fact, each of them is fine to be used if under its own sign convention (listed in table 2 in the last section of this paper), and the latter, mostly used in circuit equations, is for the purpose of intentionally grouping L, C and R as passive components (consuming electric potential energy), enabling circuit analyses more conveniently and results more understandable. As well, we re-examine a closely related subject matter: the determination of the polarities in an a.c. circuit. [ABSTRACT FROM AUTHOR]

An electrochemical pH-sensor for aqueous solutions is designed based on theworking principle of extended-gate field-effect transistor (EGFET). A commercially available metal-oxide-semiconductor field-effect transistor (MOSFET) was employed as the transducer in combination with an indium tin oxide (ITO) coated glass slide as the sensing membrane. The ITO/glass slide was patterned and encapsulated independently of any cleanroom process. The unique packaging technique provides a 6 µL cell, allowing for a low volume sample measurement. A custom electrical circuit, driving two MOSFETs in differential mode, eliminates the sensor drift, temperature, and commonmode disturbances. The differential measurement enables the sensor to operate in a reference-electrode free mode, making sensor miniaturization feasible. The sensor showed a pH-sensitivity of 52.31 mV/pH with linearity (square regression) of 0.995 in the pH-range of 8.00 to 10.80 on the first working day. Electrochemical impedance spectroscopy (EIS) technique was applied to study the corrosion of the ITO in contact with multiple buffer solutions to determine a reliable working pH-region for the sensor. A fluidic module was employed to carry out the differential measurement and calibrate the sensor to compensate for the pH-sensitivity decrease. Therefore, a low-cost and disposable EGFET-based sensor is introduced for trustworthy pH-measurements over time. [ABSTRACT FROM AUTHOR]

Higher-order topological insulators have recently witnessed rapid progress in various fields ranging from condensed matter physics to electric circuits. A well-known higher-order state is the second-order topological insulator in three dimensions with gapless states localized on the hinges. A natural question in the context of nonlinearity is whether solitons can exist on the hinges in a second-order topological insulator. Here we theoretically demonstrate the existence of stable solitons localized on the hinges of a second-order topological insulator in three dimensions when nonlinearity is involved. By means of systematic numerical study, we find that the soliton has strong localization in real space and propagates along the hinge unidirectionally without changing its shape. We further construct an electric network to simulate the second-order topological insulator. When a nonlinear inductor is appropriately involved, we find that the system can support a bright soliton for the voltage distribution demonstrated by stable time evolution of a voltage pulse.

Unwanted lithium-metal deposition on the negative electrode of a lithium-ion cell causes capacity loss due to poor lithium deposition and stripping efficiency and the possibility for internal short circuits. Internal short circuits may cause thermal runaway, which is especially dangerous in applications requiring many individual cells. This article proposes a method capable of identifying the onset of unwanted lithium deposition in-situ using cycles to full depth of discharge in a cell of any form-factor. The two most important factors affecting the average voltage of a Li-ion cell under load are the internal resistance increase and loss of lithium inventory. Increasing internal resistance increases average charge voltage and decreases average discharge voltage. Loss of lithium inventory, which occurs rapidly during unwanted lithium deposition and stripping, increases both average charge and average discharge voltage. Increasing internal resistance and loss of lithium inventory have a linearly additive effect on average voltage; therefore, tracking the average of average charge- and average discharge-voltages versus cycle count allows one to determine where rapid changes to lithium inventory onset, indicative of the onset of unwanted lithium deposition. [ABSTRACT FROM AUTHOR]

Despite the accuracy and non-intrusive nature of Electrochemical Impedance Spectroscopy, the impedance spectra of commercial Lithium-ion cells are notoriously hard to interpret. Consequently, the literature is filled with various equivalent circuit models, which differ greatly in their physical significance, but which produce very similar impedance spectra. In this paper, explicit formulas are given to convert between various equivalent circuits made of resistors and capacitors of the sort discussed in the literature. Furthermore, all these formulas have been implemented in a Python program, in the hope that studies done assuming one circuit might be compared to studies done with a different circuit, for instance. This paper considers cases where two different circuits can produce two impedance spectra which are identical. For instance, explicit conversions are given between Ladder circuits, Voight circuits, and Maxwell circuits for various time constants. This gives a conceptual foundation to explore the more difficult case of circuits producing impedance spectra which are similar to each other (e.g. within 5%). [ABSTRACT FROM AUTHOR]

A10-parameter Electrical Equivalent Circuit (10-parameter EEC) has been proposed to evaluate the electrochemical characterizations which are resistance, reactance and relaxation frequency of Lithium-ion battery (LIB) slurry under different components weight ratio of three samples composed of PVDF-NMP solution, Carbon Black (CB) absent slurry and CB present slurry. The 10-parameter EEC is constructed by combining the internal structure of LIB slurry and the electrochemical responses of three samples. Four conclusions are clarified by fitting Electrochemical Impedance Spectroscopy (EIS) Nyquist and Bode plots with the 10-parameter EEC. Firstly, the standard deviation S of the 10-parameter EEC 10-p> = 14.3% is lower than that of a conventional 8-parameter EEC 8-p> = 30.6% by πS = 16.3%. Secondly, the resistance of electric double layer (EDL) Rdl is firstly increased and then decreased as LiCoO2 particles weight ratio wtLiCoO2 is increased, which is well explained by LiCoO2-PVDF ratio effect. Thirdly, the resistances of PVDF-NMP solution RSO and conductive path Rp are the resistances of LiCoO2-NMP interface dispersion and PVDF-NMP solution dispersion in LIB slurry. Lastly, relaxation frequencies of LiCoO2-NMP interface dispersion frelax, high and PVDF-NMP solution dispersion frelax, low obtained from EIS experiment can be represented by those of frelax1 and frelax2 calculated from the 10-parameter EEC. [ABSTRACT FROM AUTHOR]

We report on the photovoltaic performance of liquid-junction S2Se3 semiconductor-sensitized solar cells (SSCs), prepared by growth of Sb2Se3 nanoparticles on a nanoporous TiO2 electrode using the solvothermal method. The growth of nanoparticles was investigated as a function of reaction time and solution concentration. The optimal sample was obtained by reacting a 0.1 M antimony solution with a 0.09 M selenium solution for 16 h. The best cell yielded an open-circuit voltage of 0.51 V, a short-circuit current density of 4.14 mA/cm², a fill factor of 55% and an efficiency of 1.08% under 100 mW/cm² illumination. A potential advantage is that the Sb2Se3 SSCs are stable in the polyiodide electrolyte. The optical absorption spectra suggest that, with improving sample growth, Sb2Se3 solar cells could achieve efficiencies significantly higher than the present value. [ABSTRACT FROM AUTHOR]

Glyoxylic acid is seen as a promising candidate to replace formaldehyde as reducing agent in electroless Cu baths. For deposition on ruthenium, the anodic reaction of glyoxylic acid has been evaluated and compared to formaldehyde using linear sweep voltammetry. Significant differences were observed for the deposition of copper on ruthenium. First of all. a faster nucleation was inferred from open-circuit potential measurements, which is beneficial as it reduces the total process time. Secondary, we found 2.2' bipyridyl worked as stabilizer and brightener in this glyoxylic acid-based electroless bath. Thirdly, the purity of the copper films improved when 2,2' bipyridyl was present in the solution. Using the optimized composition, we demonstrate a conformai Cu seed layer .deposition (~100 nm) inside high aspect ratio (16.7) through-Si vias. This work shows the feasibility for electroless Cu seeding in a through-Si via metallization sequence. [ABSTRACT FROM AUTHOR]

AIN substrates have been extensively used for heat dissipation, especially in high-power light-emitting diodes (LEDs). However, the AIN substrate is an electric insulator and thus needs to be metalized to serve as an electric circuit carrier and heat conductor for LED packaging. Herein, we propose a wet process that can be performed at room temperature to metallize AIN substrates. The wet metallization process involves copper electroless deposition and copper electroplating. The catalyst used for the copper electroless deposition was PdCL2, which was chemically grafted onto the AIN surface. The chemical grafting agent was 3-(2- aminoethylamino)propyltrimethoxysilane (APTMS). Before the chemical grafting step, an etching step in KOH solution was critical for good adhesion of the plated copper layer. The electroless copper depositions were catalyzed using chemically grafted Pd and a commercial Sn/Pd colloid. An adhesion comparison test of the plated copper layers was performed to demonstrate that the copper adhesion performance obtained with the chemically grafted Pd process was substantially better than that obtained with the commercial Sn/Pd colloid process. [ABSTRACT FROM AUTHOR]

A method for the parameterization of the electrical properties of bidirectional air electrodes in alkaline media is introduced. Through this method a distinctive characterization of bidirectional air electrodes can be performed in their whole potential range of operation. Hereby a quantitative comparison of different types of air electrodes can be made. The method bases on a large-signal electrical equivalent circuit and in contrast to electrochemical impedance spectroscopy (EIS) the circuit parameterizes the electrical properties of bidirectional air electrodes in their potential range of operation. The electrical elements of the equivalent circuit refer to the essential electrochemical and physical characteristics of the electrode. The methods for the determination of the containing element parameters are explained, linking them to the electrochemical characteristics of air electrodes. In conclusion a comparison between the real electrical behavior of an air electrode and a simulation of the evaluated equivalent circuit is made. [ABSTRACT FROM AUTHOR]

In the current investigation modeling of two half cells (LiMn2O4 cathode and carbon anode) followed by modeling of the complete cell of the battery employing Grand Canonical Monte Carlo simulations to evaluate open circuit potential and energetic of the process involved had been carried out. Current model takes into account the effect of electrolyte and temperature variations on various battery parameters like open circuit potential, cell current, cell voltage and free energy of Li+ intercalation/deintercalation. Estimation of open circuit potential (OCV) of Lithium ion batteries becomes vital as it is a crucial parameter in (i) estimating diffusion coefficient of lithium in the electrode material during charge/discharge process, (ii) obtaining entropy of the reaction and internal energy calculations and (iii) understanding thermal runaway problems. The strong dependence of OCV with the state of charge (SOC) of the battery and temperature makes the prediction more difficult. To avoid computational tediousness, Grand Canonical Monte Carlo technique coupled with multiscale simulation is employed to predict experimental OCV of LiMn2O4 cathode material in the presence of electrolyte solution. [ABSTRACT FROM AUTHOR]

Based on an innovative application of van der Pauw's theory, a system was developed for the absolute measurement of electrolytic conductivity in aqueous solutions. An electrolytic conductivity meter was designed that uses a four-electrode system with an axial–radial two-dimensional adjustment structure coupled to an ac voltage excitation source and signal collecting circuit. The measurement accuracy, resolution and repeatability of the measurement system were examined through a series of experiments. Moreover, the measurement system and a high-precision electrolytic conductivity meter were compared using some actual water samples. [ABSTRACT FROM AUTHOR]

In this paper, the crossing point property of the i–v hysteresis curve in a memristor–capacitor (MC) circuit is analyzed. First, the ideal passive memristor on the crossing point property of i–v hysteresis curve is studied. Based on the analysis, the analytical derivation with respect to the crossing point location of MC circuit is given. Then the example of MC with linear memristance-versus-charge state map is demonstrated to discuss the drift property of cross-point location, caused by the frequency and capacitance value. [ABSTRACT FROM AUTHOR]

The electrical impedance of samples of mouse brain cortex has been measured between 4.7 kHz and 2.0 MHz. Brain slices of thickness 400 μm were prepared from two mice. Each slice was placed in either normal artificial cerebrospinal fluid or magnesium-free artificial cerebrospinal fluid; the latter induces seizure-like electrical behaviour. A total of 74 samples of cortex of approximate size 2 mm × 2 mm were then cut from these slices. Each sample in turn was placed between two flat Ag/AgCl electrodes and electrical impedance measured with an Agilent E4980A four-point impedance monitor. The measurements showed two regions of significant dispersion. Circuits based on the Cole–Cole and Fricke models, consisting of inductive, nonlinear capacitive and resistive elements were used to model the behaviour. Distributions of values for each circuit element have been determined for the samples prepared in seizing and non-seizing conditions. Few differences were found between the values of circuit elements between the seizing and non-seizing groups. [ABSTRACT FROM AUTHOR]

The partial discharge (PD) and electric breakdown mechanisms in SF6 at a plug contact in the pressure range 25–150 kPa were investigated at ambient temperature in a plug–plate arrangement. This parameter range has similar particle number densities as in the previous investigation of the dielectric recovery in a high-voltage circuit breaker (Seeger et al 2012 J. Phys. D: Appl. Phys.45 395204), where optical access was limited and the relevant parameters of pressure and temperature could only be determined indirectly by computational fluid dynamic simulations. The present investigation did not have these limitations, since the pressure and temperature were well defined. Optical observation by an image intensified high speed camera in combination with a photo multiplier tube allowed an understanding of the various mechanisms for the PDs and breakdown to be gained. The breakdown fields and PD parameters could be well described by a simple leader model in the pressure range 75–150 kPa for negative polarity and above 25 kPa for positive polarity. Discrepancies with the model are observed below 75 kPa for negative polarity and at 25 kPa for positive polarity. This could be explained by a slow, repetitive heating mechanism which has not been reported so far. [ABSTRACT FROM AUTHOR]

In this paper, controlling chaos when chaotic ferroresonant oscillations occur in a voltage transformer with nonlinear core loss model is performed. The effect of a parallel metal oxide surge arrester on the ferroresonance oscillations of voltage transformers is studied. The metal oxide arrester (MOA) is found to be effective in reducing ferroresonance chaotic oscillations. Also the multiple scales method is used to analyze the chaotic behavior and different types of fixed points in ferroresonance of voltage transformers considering core loss. This phenomenon has nonlinear chaotic dynamics and includes sub-harmonic, quasi-periodic, and also chaotic oscillations. In this paper, the chaotic behavior and various ferroresonant oscillation modes of the voltage transformer is studied. This phenomenon consists of different types of bifurcations such as period doubling bifurcation (PDB), saddle node bifurcation (SNB), Hopf bifurcation (HB), and chaos. The dynamic analysis of ferroresonant circuit is based on bifurcation theory. The bifurcation and phase plane diagrams are illustrated using a continuous method and linear and nonlinear models of core loss. To analyze ferroresonance phenomenon, the Lyapunov exponents are calculated via the multiple scales method to obtain Feigenbaum numbers. The bifurcation diagrams illustrate the variation of the control parameter. Therefore, the chaos is created and increased in the system. [ABSTRACT FROM AUTHOR]

The Townsend discharge mechanism has been explored in a planar microelectronic gas discharge device (MGDD) with different applied voltages U and interelectrode distance d under various pressures in air. The anode and the cathode of the MGDD are formed by a transparent SnO2 covered glass and a GaAs semiconductor, respectively. In the experiments, the discharge is found to be unstable just below the breakdown voltage Ub, whereas the discharge passes through a homogeneous stable Townsend mode beyond the breakdown voltage. The measurements are made by an electrical circuit and a CCD camera by recording the currents and light emission (LE) intensities. The intensity profiles, which are converted from the 3D light emission images along the semiconductor diameter, have been analysed for different system parameters. Different instantaneous conductivity σt regimes are found below and beyond the Townsend region. These regimes govern the current and spatio-temporal LE stabilities in the plasma system. It has been proven that the stable LE region increases up to 550 Torr as a function of pressure for small d. If the active area of the semiconductor becomes larger and the interlectrode distance d becomes smaller, the stable LE region stays nearly constant with pressure. [ABSTRACT FROM AUTHOR]

Through-hole (TH) filling of a printed circuit board (PCB) was conducted with a copper electroplating solution. Tetranitroblue tetrazolium chloride (TNBT) was used as an inhibitor and acetic acid electrolyte instead of a traditional H2SO4 electrolyte was used for the copper electroplating. Moreover, functional insoluble anodes (DT) that were activated with iridium-based mixed metal oxides on Ti meshes were used instead of conventional soluble anodes (i.e., P-doped Cu). The TH filling performance of the copper electroplating solution was significantly enhanced when acetic acid electrolyte and DT anodes were used simultaneously in the copper electroplating bath. [ABSTRACT FROM AUTHOR]

This paper presents a compact power electronic device, called an ‘electrodynamic transformer (ET)’, that transfers electrical power between isolated circuits through electrodynamically coupled vibrations of a mechanical beam structure. Background motivating factors are discussed, and an equivalent circuit model of the ET is presented. A microscale (10 mm3) ET is designed, fabricated and characterized, achieving ∼40% maximum efficiency. Taking advantage of the unique circuit topology of the ET equivalent circuit model, a dc/ac power inverter is then implemented with only two external components, a MOSFET and a capacitor. [ABSTRACT FROM AUTHOR]

Electromagnetically induced transparency (EIT) and EIT-like effects have been investigated in a wide variety of coupled resonant systems. Here, a classification of the phase characteristics of the EIT-like spectral responses is presented. Newly identified phase responses reveal unexplored operation regimes of EIT-like systems. Taking advantage of these new phase regimes, one can obtain group delay, dispersion and nonlinearity properties greatly enhanced by almost one order of magnitude, compared to the traditionally constructed EIT-like devices, all of which breaks the fundamental limitation (e.g. delay–bandwidth product) intrinsic to atomic EIT and EIT-like effects. Optical devices and electrical circuits are analyzed as examples showing the universality of our finding. We show that cavity quantum electrodynamics (QED)-based quantum phase gates can be greatly improved to achieve a phase shift of π. The new phase characteristics are also believed to be useful to build novel doubly resonant devices in quantum information based cavity QED, optomechanics and metamaterials. [ABSTRACT FROM AUTHOR]

EIS ha s been acknowledged to be a powerful tool for investigating the kinetic mechanisms of charge transfer processes at elec-trode/solution interfaces. The method of using equivalent electrical circuits (EECs) has been most frequently used for interpreting measured EIS spectra. But the mechanistic information that this method can deliver is very limited. In this work, an alternative but innovative method, which combines the EECs and the mechanism analysis, is developed. With anodically polarized, oxide film covered titanium in NaF-containing perchloric acid solutions as an example, a detailed procedure is described and discussed for obtaining kinetic information (such as the rate constant, rate-determining step) from the results estimated by EECs. Two double-step mechanism models for anodized titanium are proposed and tested based on the strategy of the developing approach. [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]

This paper extends the interesting work of a previous contributor concerning the analogies between physical phenomena such as mechanical collisions and the transfer of power in an electric circuit. Emphasis is placed on a mathematical function linking these different areas of physics. This unifying principle is seen as an exciting opportunity to enhance both teaching and learning by illustrating the power and subtleties of similarities in physics. [ABSTRACT FROM AUTHOR]

The cavity-mode resonance effect could result in significant degradation of the shielding effectiveness (SE) of a shielding enclosure around its resonance frequencies. In this paper, the influence of coated wall loss on the suppression of the resonance effect is investigated. For this purpose, an equivalent circuit model is employed to analyze the SE of an apertured rectangular cavity coated with an inside layer of resistive material. The model is developed by extending Robinson's equivalent circuit model through incorporating the effect of the wall loss into both the propagation constant and the characteristic impedance of the waveguide. Calculation results show that the wall loss could lead to great improvement on the SE for frequencies near the resonance but almost no effect on the SE for frequencies far away from the resonance. [ABSTRACT FROM AUTHOR]

A high-temperature-resistant bond withstanding up to 415°C for SiC power devices is realized at 260°C with a Cu/Sn powder paste and an electroless nickel plated Si3N4/Cu circuit substrate. The bond was formed by using transient liquid phase sintering (TLPS). The bond strength tested at 300°C increases with increasing aging time at 300°C, from the original 40 MPa to 50 MPa after aging at 300°C for 200 h. This is attributed to phase transformation from Cu6Sn5 formed during TLPS to Cu3Sn in the bond during aging. We observed an η-(Cu,Ni)6.26Sn5 phase at the interface between the TLPS Cu-Sn bond and Ni(P) layer. The interface between the TLPS Cu-Sn bond and Si3N4/Cu/Ni(P)/Ag substrate exhibits very high stability, characterized by a very slow Ni(P) layer consumption rate and Ni3P growth rate. The TLPS Cu-Sn bond on a 5 μm-thick electroless plated nickel layer is expected to have a life time beyond 105 h during storage at 300°C. [ABSTRACT FROM AUTHOR]

The future of nanoplasmonic interconnects for next-generation computing platforms is dependent on the development of active devices for compensating the high losses from the metallic waveguides. We present and investigate the gain characteristics of an electrically pumped nanoplasmonic In0.485Ga0.515As amplifier design for the telecommunications wavelength of 1.55 μm through 3D finite difference time domain simulations. The device is shown to be capable, when coupled to a nanoplasmonic interconnect network, of restoring signal amplitude after more than a hundred micrometers of propagation. Up to 500 GHz pulse repetition rates are maintained without significant pulse distortion, offering the possibility of incorporating ultrahigh bandwidth nanoplasmonic interconnects into hybrid optical–electrical circuits. [ABSTRACT FROM AUTHOR]