Circuit Resistance Research Articles

High temperature electromigration behavior of cobalt lines observed by in situ transmission electron microscopy

As industrial practices shift away from Cu as the initial back-end-of-line interconnect material due to size limitations, new candidate metals are being tested and characterized. Electromigration resistance is particularly important in ultra-narrow lines and an in situ study provides unique insight into the formation and progression of electromigration damage. This, in turn, helps to inform device design so that electromigration resistant circuits can be produced efficiently. In this work, the authors demonstrate an in situ transmission electron microscopy technique for electromigration analysis of Cu replacement metals in microelectronic interconnects. Using this method, candidate metal lines can be tested at high current densities, ∼5×106 A/cm2, at controllable temperatures over the range of 300–1000 °C. In this work, cobalt lines are tested in the range of the effective valence inversion temperature. The analysis examines void nucleation, growth, and migration as a function of temperature and line geometry. We find that there is a relative insensitivity of failure time to operating temperature, with samples tested between approximately 600 and 900 °C having roughly equivalent failure times. We ascribe this result to a combination of linewidth effects and a decrease in the magnitude of the effective valence approaching the inversion temperature. Failure mechanism is also not affected by temperature in this range, with the primary determining factor being the linewidth and corresponding availability of grain boundaries for diffusive mass transport. We also observe increased lifetimes of devices with uniform temperatures compared to those in which large thermal gradients exist.

Construction of an Ecological Security Pattern in Yangtze River Delta Based on Circuit Theory

Ecological corridors can improve the connectivity between different habitat regions, ultimately halting the loss of biodiversity and habitat fragmentation. Building ecological corridors is a crucial step in protecting biodiversity. Ecological corridors had previously been built primarily on nature reserves, ignoring ecosystem services. In this study, a novel approach to building ecological corridors is put forth that takes into account a variety of ecosystem services, morphological spatial pattern analysis (MSPA), and connectivity methodologies to identify significant ecological sources. Ecological corridors and significant strategic nodes are created based on the minimum cumulative resistance model (MCR) and circuit theory in order to construct the Yangtze River Delta’s ecological security pattern. The research found that: (1) the identified ecological sources are 90,821.84 km2, and the total length of ecological corridors is 4704.03 km. (2) In total, 141 ecological restoration areas are identified, with a total area of 2302.77 km2; 151 ecological protection areas are identified, with a total area of 5303.43 km2. This study can provide valuable insights into the establishment of ecological patterns and the construction of priority restoration and protection areas in the ecological restoration of the Yangtze River Delta.

Design and Validation of a V-Gate n-MOSFET-Based RH CMOS Logic Circuit with Tolerance to the TID Effect

This study designed a radiation-hardened (RH) complementary metal oxide semiconductor (CMOS) logic circuit based on an RH variable-gate (V-gate) n-MOSFET that was resistant to the total ionizing dose (TID) effect and evaluated its tolerance to radiation. Among the different CMOS logic circuits, NOT, NAND, and NOR gates were designed using V-gate n-MOSFETs by employing layout transformation techniques and standard p-MOSFETs. Before the process design, we predicted the radiation damage using modeling and simulation techniques and validated the tolerance by conducting actual radiation tests after the process design. Furthermore, we implemented the CMOS logic circuit process design in a 0.18 µm CMOS bulk process. The actual radiation test applied a total cumulative radiation dose of 25 kGy at 5 kGy per hour in a high-level gamma-ray irradiation facility. Consequently, the resistance of the RH CMOS logic circuit based on the RH V-gate n-MOSFET to the TID effect was validated through experiments.

The electrical response of refractory carbon/carbon composites to high-temperature ablation: A pathway to embedded sensing in extreme environments

High-temperature ceramics and composites are essential for leading edges on next-generation high-speed aerospace vehicles, where the surfaces are expected to see extreme temperatures and heat fluxes. However, these materials are vulnerable to in-flight degradation arising from oxidation and ablation. Due to the extreme conditions encountered during flight, even slight changes in surface properties can profoundly affect aerodynamic performance and precipitate catastrophic failure. In-flight embedded sensing is therefore critical. Unfortunately, traditional sensors either prohibitively interfere with aerodynamics or cannot survive in-flight conditions. To overcome this challenge, we explore the material-as-the-sensor paradigm for extreme environment materials. Changes in the electrical properties of a refractory carbon/carbon (C/C) composite are used as an indicator of degradation. C/C composite strips were exposed to an oxyacetylene torch to represent oxidation and ablation expected during service, and the electrical impedance of the strips was measured before and after each exposure. It was found that ablation-induced damage has a clear impact on alternating current transport that scales with increasing exposure time and ablated volume. Equivalent circuit analyses were conducted in order to better understand the nature of ablation damage on transport characteristics; it was found that the resistance of the equivalent circuit increases with increasing torch exposure time and ablated volume. This study is an important proof-of-concept result for establishing embedded sensing techniques in next-generation extreme environments.

A method for consistent cavitation bubble generation at different voltages

A study of the dynamics of a single cavitation bubble is fundamental for understanding a wide range of applications in science and engineering. Underwater electrical discharge is a widely used method for generating cavitation bubbles to study their inception, subsequent dynamics, and collapse. In this work, an existing underwater low-voltage discharge circuit for generating cavitation bubbles is improved further to get a wider range of maximum bubble radius. In this novel electric circuit design, the operating voltage can be varied (up to 420 V in steps of 60 V) by connecting a network of capacitors in different series-parallel combinations with the help of relay-based control. Therefore, this device can generate oscillating cavitation bubbles up to a maximum radius of 14 mm by adjusting the available discharge energy. A voltage sensor circuit is included in this design to measure the drop in voltage during the sparking event, and a correlation between the delivered energy and the potential energy of the bubble is established. The dependence of bubble radius on circuit resistance, electrode resistance, and electrode material is studied for the entire voltage range. A suitably rated semiconductor field effect transistor is used as a switch that enables the generation of bubbles of a consistent maximum radius and ensures the repeatability of the experiment. A high-speed imaging system is used to estimate the bubble radius and nucleation period, which are compared with the existing theoretical models based on empty cavity collapse. Results show that delaying the oxidation of electrodes with a protective layer influences the collapse phase and the average pressure inside the spark-generated bubble.

Applicability Analysis of a Multi-Filar Meander R-SFCL and an RSC-DCCB in an MMC-MTDC Grid

modular multilevel converters (MMC)-based high voltage direct current (HVDC) topology is an effective solution to solve the power transmission demand between countries. However, the initial fault current can rise to several tens of kA within a few ms by capacitor discharge during a fault. This fault current can permanently damage the converter components and cables. Therefore, to increase the stability of the system, the protection of the DC system is very important. DC system protection methods include circuit breaker technologies and current limiting technologies. We have selected a circuit breaker with combined resonant current source (RCS) and a resistive superconducting fault current limiter (SFCL) as protection methods for the DC system. The RSC-DC circuit breaker has no conduction power losses by on-state voltage drop. Therefore, it can provide stable interruption compared to a solid-state DC circuit breaker. Since the resistive SFCL has a very fast response time, it can effectively limit the rapidly rising initial fault current. We wound the superconducting tape by the multi-filar meander method. This method can increase the length of the superconducting tape used and speed up the bubble diffusion during quenching. We modeled an MMC-HVDC grid, resistive SFCL, and RCS DC circuit breaker using PSCAD/EMTDC. In this paper, the interrupting and current limiting characteristics are discussed when the resistive SFCL and the RCS-DC circuit breaker proposed by us are connected to the MMC-based MTDC grid. In the simulation, the current limiting factor of resistive SFCL was up to about 58%. In addition, the combination of resistive SFCL and RCS-DC circuit breaker can shorten the interruption time when the fault occurs.

An ultra-efficient design of fault-tolerant 3-input majority gate (FTMG) with an error probability model based on quantum-dots

Quantum-dot cellular automata (QCA) has recently attracted significant notice thanks to their inherent ability to decrease energy dissipation and decreasing area, which is the primary need of digital circuits. However, the lack of resistance of QCA circuits under defects in previous works is a vital challenge affecting the stability of the circuit and output production. In addition, with the high defect rate in QCA, suggesting resistance and stable structures is critical. Furthermore, the 3-input majority gate is a fundamental component of QCA circuits; therefore, improving this essential gate would enable the development of fault-tolerant circuits. This paper recommends a 3-input majority gate which is 100% fault-tolerant against single-cell omission defects. Moreover, the fundamental gates are introduced based on the proposed gate. In addition, an adder and a 1:2 decoder are also designed. Using QCADesigner 2.0.3 and QCAPro software, simulations of structures and analysis of power consumption are performed.

Quantification of Si, Al, Ti and O Composition in Si/Al Oxide Based Synaptic Resistor Circuits.

Quantification of Si, Al, Ti and O Composition in Si/Al Oxide Based Synaptic Resistor Circuits.

Electrical Circuit Modeling of Nanofluidic Systems

AbstractNanofluidic systems exhibit transport characteristics that have made technological marvels such as desalination and energy harvesting possible by virtue of their ability to influence small currents due to selective ion transport. Traditionally, these applications have relied on nanoporous membranes whose complicated geometry impedes a comprehensive understanding of the underlying physics. To bypass the associated difficulties, we consider the simpler nanochannel array and elucidate the effects of interchannel interactions on the Ohmic response. It is demonstrated that a nanochannel array is equivalent to an array of mutually independent but identical unit‐cells whereby the array can be represented by an equivalent electrical circuit of resistances connected in a parallel configuration. The model is validated using numerical simulations and experiments. The approach to modeling nanofluidic systems by their equivalent electrical circuit provides an invaluable tool for analyzing and interpreting experimental measurements.

Probing the Ion Transport Properties of Ultrashort Carbon Nanotubes Integrated with Supported Lipid Bilayers via Electrochemical Analysis.

Supported lipid bilayers (SLBs) are commonly used to investigate interactions between cell membranes and their environment. These model platforms can be formed on electrode surfaces and analyzed using electrochemical methods for bioapplications. Carbon nanotube porins (CNTPs) integrated with SLBs have emerged as promising artificial ion channel platforms. In this study, we present the integration and ion transport characterization of CNTPs in in vivo environments. We combine experimental and simulation data obtained from electrochemical analysis to analyze the membrane resistance of the equivalent circuits. Our results show that carrying CNTPs on a gold electrode results in high conductance for monovalent cations (K+ and Na+) and low conductance for divalent cations (Ca2+).

Development of thermal conductivity model with use of a thermal resistance circuit for metallic UO2 microcell nuclear fuel pellets

A metallic microcell UO2 pellet has a microstructure where a metal wall is connected to overcome the low thermal conductivity of the UO2 fuel pellet. It has been verified that metallic microcell fuel pellets provide an impressive reduction of the fuel centerline temperature through a Halden irradiation test. However, it is difficult to predict the effective thermal conductivity of these pellets and researchers have had to rely on measurement and use of the finite element method. In this study, we designed a unit microcell model using a thermal resistance circuit to calculate the effective thermal conductivity on the basis of the microstructure characteristics by using the aspect ratio and compared the results with those of reported metallic UO2 microcell pellets. In particular, using the thermal conductivity calculated by our model, the fuel centerline temperature of Cr microcell pellets on the 5th day of the Halden irradiation test was predicted within 6% error from the measured value.

Dynamic simulation of rail potential considering rail skin effect

The existing simulation of rail potential only considers the equivalent DC resistance and 1st-order RL circuit of a rail. However, the rail current contains a large number of harmonic components, which greatly affects the calculation of rail potential. To accurately calculate the rail potential, the rail is equivalent to a tubular conductor considering the skin effect. The improved equivalent circuit of reflux system is established by vector fitting method (VF), and the 8th-order foster equivalent circuit of rail is built. The dynamic simulation model considering multi-trains, multi-stations, and over voltage protection device (OVPD) actions is established. By measuring the actual internal impedance of the rail, the parameters of the equivalent tubular conductor model of the rail are fitted with the least square method. The maximum error between VF method and finite element simulation, field test results is 6.531%, and 7.271%, respectively. Compared with the equivalent of the 1st-order RL circuit and DC resistance, the rail potential results of the modified model are significantly improved, the rail potential is evaluated more accurately.

Highly energy-efficient and safe-environment-friendly ultra short electrical arc machining for titanium alloy: Mechanism, characteristics, and parameter estimation

A higher energy-efficient and safe-environment-friendly method named ultra short electric arc machining (US-EAM) was proposed to meet the imperative needs of cleaner production. Low loop circuit resistance, long discharge time, and continuous energy output ensured highly stable and low energy output at low voltages in US-EAM. Voltage-current (V-A) analysis and single-point experiments investigated the machining stability. Typical US-EAM characteristics, such as the material removal rate (MRR), specific energy consumption (SEC), relative electrode wear rate (REWR), and surface characteristics, were investigated as a function of the electrode rotation speed, gas pressure, and milling depth. Moreover, the optimal parameters were obtained through the grey correlation situation decision method, showing that the MRR reached 17100 mm3/min, SEC was limited to 27.296 kJ/cm3, and the REWR was limited to 1.487%.

A Review of Piezoelectric Footwear Energy Harvesters: Principles, Methods, and Applications.

Over the last couple of decades, numerous piezoelectric footwear energy harvesters (PFEHs) have been reported in the literature. This paper reviews the principles, methods, and applications of PFEH technologies. First, the popular piezoelectric materials used and their properties for PEEHs are summarized. Then, the force interaction with the ground and dynamic energy distribution on the footprint as well as accelerations are analyzed and summarized to provide the baseline, constraints, potential, and limitations for PFEH design. Furthermore, the energy flow from human walking to the usable energy by the PFEHs and the methods to improve the energy conversion efficiency are presented. The energy flow is divided into four processing steps: (i) how to capture mechanical energy into a deformed footwear, (ii) how to transfer the elastic energy from a deformed shoes into piezoelectric material, (iii) how to convert elastic deformation energy of piezoelectric materials to electrical energy in the piezoelectric structure, and (iv) how to deliver the generated electric energy in piezoelectric structure to external resistive loads or electrical circuits. Moreover, the major PFEH structures and working mechanisms on how the PFEHs capture mechanical energy and convert to electrical energy from human walking are summarized. Those piezoelectric structures for capturing mechanical energy from human walking are also reviewed and classified into four categories: flat plate, curved, cantilever, and flextensional structures. The fundamentals of piezoelectric energy harvesters, the configurations and mechanisms of the PFEHs, as well as the generated power, etc., are discussed and compared. The advantages and disadvantages of typical PFEHs are addressed. The power outputs of PFEHs vary in ranging from nanowatts to tens of milliwatts. Finally, applications and future perspectives are summarized and discussed.

In Situ Measurement of Dynamic Internal Short Circuit Resistance during Nail Penetration of Lithium-Ion Cells and its Implications on Cell Robustness and Abuse Tolerance

Here we report a method for in situ measurement of internal short circuit (ISC) resistance during nail penetration testing of lithium-ion cells. The method is demonstrated with dry cells, wet dummy cells, and working cells using a small nail and slow penetration speed. ISC current and ISC temperature are also measured during the tests. It is confirmed that the ISC resistance changes dramatically, by several orders of magnitude, during nail penetration. More importantly, it is found that the stable resistance after full penetration is much higher than the lowest dynamic resistance at earlier stages of nail penetration. Analysis based on such a stable ISC resistance would underestimate the risk of thermal runaway during nail penetration tests. It is also found that ISC in some cases may be mitigated due to melting or rupture of aluminum foil surrounding the nail, implying a mechanism that may be able to be used towards the design of more robust/abuse tolerant Li-ion cells. Lastly, it is found that nail penetration using a larger nail reduces ISC resistance during penetration of cells but the general behaviors of ISC resistance are similar to those during smaller nail penetration.

Robust temperature tracking and estimation for resistive heater circuit board with implementation

SummaryResistive heating is an efficient method for temperature control in many applications that need robust control designs. Very few attempts have been reported in this direction to deal robustness issues like parametric variations, disturbances and uncertainties. Moreover, there are hardly any laboratory scaled setups available, that are of low cost and provide ease of implementation for such applications to test various algorithms. To that end, lately a resistive heater circuit board (RHCB) setup has become a benchmark setup for testing. For which, available control schemes largely use PID based schemes so far that are not robust. Besides, they employ numerical derivatives of measurements, resulting in the added noise. To circumvent these issues and to address the mentioned literature gap, this paper reports new experimental and simulation studies by developing new robust control and estimation designs for temperature tracking. We design via sliding mode algorithms, a sliding mode observer (SMO) and discrete‐time sliding mode controller (DTSMC) for an uncertain system of RHCB. The proposed controller outperforms the existing PID schemes and tracks the temperature reference accurately, despite the uncertainties. Moreover, SMO robustly estimates the temperature measurements and provide accurate signal for the control purpose. In addition, this study also reports a first of its kind application of such DTSMC and SMO, for which the idea of using different temporal designs for each of them is employed and integrated together for the ease of implementation on RHCB. Thus, the novelty also lies in how to judicially stitch these approaches and showcase their efficacy through simulation and experimental validations.

Resistance Value Analysis Study using the Wheatstone bridge circuit method and the Circuit Wizard and Proteus 8 simulators

The Wheatstone bridge circuit is one configuration resistor circuit that serves to measure changes in resistance (resistance) is very small, and has been widely used in circuits sensors. This circuit is arranged like a rhombus, at least four resistors (R1, R2, R3, R4), one of which is a resistor not fixed (R3) which usually uses a variable resistor. Then, one of them is a resistor whose resistance value is sought (R4). This study aims to explore a series of bridges Wheatstone with three scenarios. First, the search for one of the the correct value of the resistor (R4) when the state is balanced, or when the current is flow at point AB is equal to Zero (IAB = 0 A). Second, measure Wheatstone bridge voltage (VAB) with varying resistor values. Third, look for one of the resistor values (R4), the replacement resistance value of all resistance (REq) at the state of balance, and the total current flows (ITotal) in the Wheatstone bridge circuit when VAB = 0 Volts. The analysis utilizes two offline simulators, namely Circuit Wizard v.1.15 and Proteus v.8.5. Then the simulation results all three are compared with theoretical calculations. Simulation results of The three simulators prove that the current and voltage values on the Wheatstone circuit is in accordance with theoretical calculations, where IAB = 0 A and VAB = 0 V if the state is balanced. In no state equilibrium, then there will be a current flowing from point A to point B so there is a potential difference, where the value of this potential difference is the same
 with VA – VB. This article also examines the performance and trade-offs of the three simulators when experimenting with circuits Wheatstone bridge based on hands-on experience from the researcher's point of view

Antimicrobial Susceptibility of Commensal E. coli Isolated from Wild Birds in Umbria (Central Italy).

The role of wildlife, including birds, in antimicrobial resistance is nowadays a speculative topic for the scientific community as they could be spreaders/sources of antimicrobial resistance genes. In this respect, we aimed to investigate the antimicrobial susceptibility of 100 commensal Escherichia coli strains, isolated from wild birds from an Umbrian rescue centre and admitted to the Veterinary Teaching Hospital of Perugia (Central Italy) mainly for traumatic injuries. The possible presence of Salmonella spp. and ESBL-producing E. coli was also estimated. The highest prevalence of resistance was observed for ampicillin (85%) and amoxicillin/clavulanic acid (47%), probably due to their extensive use in human and veterinary medicine. Seventeen out of the one hundred E. coli isolates (17%) displayed a multidrug-resistance profile, including the beta-lactam category, with the most common resistance patterns to three or four classes of antibiotics. Resistance to ciprofloxacin, cefotaxime and ceftazidime exhibited values of 18%, 17% and 15%, respectively. Eight out of the hundred E. coli isolates (8%) were ESBL and seven showed multidrug resistance profiles. Salmonella spp. was not isolated. Resistance to third-generation cephalosporins, also detected in long-distance migratory birds, suggests the need for monitoring studies to define the role of wild birds in antimicrobial resistance circuits.

Generalised energy equipartition in electrical circuits

In this brief note, we demonstrate a generalised energy equipartition theorem for a generic electrical circuit with Johnson-Nyquist (thermal) noise. From quantum mechanical considerations, the thermal modes have an energy distribution dictated by Planck's law. For a resistive circuit with some inductance, it is shown that the real part of the admittance is proportional to a probability distribution function which modulates the contributions to the system's mean energy from various frequencies of the Fourier spectrum. Further, we analyse the case with a capacitor connected in series with an inductor and a resistor. The results resemble superstatistics, i.e. a superposition of two statistics and can be reformulated in the energy representation. The correct classical limit is obtained as $\hbar \rightarrow 0$.

Experimental and finite element analysis of utilizing rectangular and trapezoidal piezoelectric energy harvester with arrays of auxetic cells

Present study develops the experimental and finite element analysis of an auxetic piezoelectric energy harvester consisting of a cantilever, auxetic substrate, and piezoelectric layer. Firstly, five auxetic models with 1, 4, 9, 16, and 25 honeycomb auxetic cells are presented. Harvested power and stress distribution of the piezoelectric layer for these models are compared with plain piezoelectric energy harvester. All the analysis has been performed using the experimental tests and finite element method. Mesh size sensitivity analysis of the finite element model is presented, and it is verified by previous experimental studies. The model with 25 auxetic cells harvests more power than other models. Furthermore, comparing stress distribution on the piezoelectric layer of these models indicates that increasing the number of auxetic cells leads to increasing the average stress on the piezoelectric layer. The present investigation illustrates that harvested power of an auxetic energy harvester in resonant frequency could improve to twenty times more than a plain harvester. Besides, the new auxetic model with trapezoidal geometry is presented in the present paper. Utilizing this model as the substrate in a piezoelectric energy harvester leads to increasing the efficiency of the energy harvester by 82.5%. The damping ratio of the auxetic energy harvester has been measured by experimental investigation. Also, experimental analysis has been performed to find the optimum energy harvester circuit resistor. The density of the harvested power for the trapezoidal energy harvester with an optimum circuit resistor is 107% more than the rectangular energy harvester.