Mixed Circuits Research Articles

Improvement of the methodology for assessing power losses in in-plant power grids

To improve the reliability of calculations of electric power losses in low-voltage electric networks, it is necessary to take into account the influence of the main parameters of electrical equipment. In the course of the study, a structural diagram and an algorithm for determining the equivalent resistance of the section of the shop network have been proposed; the main factors determining the equivalent resistance of the circuit (resistance of low-voltage switching devices, heating temperature of conductors, ambient temperature, equipment load factor) have been identified; graphical dependencies of the change in the equivalent resistance of the radial and trunk sections of the circuit on the mean square equipment load factor and the heating temperature of conductors have been shown. The total error in estimating the equivalent resistance when calculating without taking into account the main studied parameters of equipment for radial, trunk and mixed circuits is 40 % or more. The error in the results of calculations without taking into account the resistance of contact connections of switching devices can reach 80 %. The obtained dependencies of the equivalent resistance on the main parameters of the equipment are recommended for use to improve the reliability of estimating electric power losses in intra-plant electric networks.

Operational Amplifiers Defect Detection and Localization Using Digital Injectors and Observer Circuits

Operational amplifiers (op amps) are fundamental blocks that find wide application both as stand-alone devices and as crucial blocks embedded in various Systems on Chips (SoCs). Achieving high defect coverage, as well as performing defect localization in these circuits, has proven to be a difficult/expensive task, even with sophisticated testing circuitry. The ISO 26262 standard for functional safety (FuSa) includes the stringent requirement that an automotive IC must have a very high defect coverage. This reinforces the need to ensure the functionality of analog and mixed (AMS) circuits, especially in mission critical applications. This paper presents an all-digital op amp defect detection, diagnosis, and localization method that can be used both for production and in-field tests and discusses various implementation of the proposed method. We validated our results using extensive transistor-level simulations of multiple op amp architectures using TSMC 180 nm technology. Across op amp architectures and multiple implementation approaches, we achieved a worst-case and best-case defect coverage of 94.5% and 99%, respectively. Furthermore, in this work, we also propose a defect diagnosis and localization strategy using recorded bit streams from states of digital injectors and detectors.

PrivData Network: A Privacy-Preserving On-Chain Data Factory and Trading Market

Privacy concerns often raise when sensitive data are collected, traded, and processed. The data owner typically loses her ultimate control of the data after data-outsourcing. In this work, we present the PrivData Network – a community-controlled privacy-preserving data factory and trading market. It can be viewed as a standalone data ecosystem that enables privacy-preserving data-driven workflows in a controlled environment for orchestrating and automating data movement and data transformation. In particular, we design a data encapsulation mechanism with privacy assurance, which can guarantee data privacy, usage policy compliance and metadata validity. We also design a privacy policy language and utilize a static analysis library that transfers the program to the defined policy language. To ensure the correctness of data processing, we propose a publicly verifiable secure multiparty computation protocol for mixed circuits, which guarantees the output correctness even if all parties are corrupted. Its online efficiency is comparable to conventional semi-honest secret-sharing-based MPC schemes. Finally, we implemented a prototype of our system in C++ and benchmark it on various tasks, such as biometric matching, logistic regression, and decision trees, etc.

Suitability of applying ultrathin SOI‐based PIN diodes to photodetection of UV wavelength

AbstractThis work intends to investigate the impact of silicon layer thickness and substrate biasing on the UV photodetection efficiency of PIN diodes fabricated with ultra‐thin body and buried oxide (UTBB silicon‐on‐insulator [SOI]) technology, aiming to verify their behaviour on an ultimate commercial technology. UV photodetectors are applied in different fields, such as environmental and biomedical ones, and their implementation in UTBB SOI could enable the design of mixed circuits where data acquisition and processing could be made in the same chip, enhancing systems’ performance. It is shown that a 20‐nm‐thick silicon layer can be applied for UV photodetection and enhanced generated current is obtained when substrate bias is set to guarantee a depletion regime in the entire active layer.

DYNAP-SE2: a scalable multi-core dynamic neuromorphic asynchronous spiking neural network processor

With the remarkable progress that technology has made, the need for processing data near the sensors at the edge has increased dramatically. The electronic systems used in these applications must process data continuously, in real-time, and extract relevant information using the smallest possible energy budgets. A promising approach for implementing always-on processing of sensory signals that supports on-demand, sparse, and edge-computing is to take inspiration from biological nervous system. Following this approach, we present a brain-inspired platform for prototyping real-time event-based spiking neural networks. The system proposed supports the direct emulation of dynamic and realistic neural processing phenomena such as short-term plasticity, NMDA gating, AMPA diffusion, homeostasis, spike frequency adaptation, conductance-based dendritic compartments and spike transmission delays. The analog circuits that implement such primitives are paired with a low latency asynchronous digital circuits for routing and mapping events. This asynchronous infrastructure enables the definition of different network architectures, and provides direct event-based interfaces to convert and encode data from event-based and continuous-signal sensors. Here we describe the overall system architecture, we characterize the mixed signal analog-digital circuits that emulate neural dynamics, demonstrate their features with experimental measurements, and present a low- and high-level software ecosystem that can be used for configuring the system. The flexibility to emulate different biologically plausible neural networks, and the chip’s ability to monitor both population and single neuron signals in real-time, allow to develop and validate complex models of neural processing for both basic research and edge-computing applications.

Analog and mixed circuit analysis of nanosheet FET at elevated temperatures

In this paper, for the first time, the performance of 3D Nanosheet FETs (NSFETs) is reported in the inversion (INV), accumulation (ACC), and junctionless (JL) modes at elevated temperatures. It is observed that, as the temperature increases from 25 °C to 200 °C, a decrement of 68% in mobility is observed for INV mode. In contrast, an increment of around 29% in mobility is observed for ACC and JL modes owing to the less scattering effects. Various crucial DC and analog/RF figures of merit (FOMs), such as SS, DIBL, gm, f T, etc, are assessed for different temperatures in all three modes. Further, the impact of temperature on circuit performance is demonstrated. From the circuit analyses, at 25 °C, an increment of around 12% in propagation delay is noticed for the JL and ACC mode inverter compared to the INV mode inverter due to higher I ON for INV mode. However, at 200 °C, JL inverter outperforms INV and ACC modes because of an increment in mobility. Moreover, for ring oscillator (RO), an oscillation frequency of 43.39 GHz, 38.9 GHz and 38.8 GHz for INV, ACC and JL mode ROs at 25 °C, whereas oscillation frequencies of 27.08 GHz, 39.2 GHz and 42.88 GHz are noticed for INV, ACC and JL mode ROs at 200 °C respectively. Though JL NSFET offers less intrinsic capacitances, at 25 °C, the frequency of oscillations (f osc) is high for INV mode because of higher I ON. Whereas, at 200 °C, the JL mode outperforms due to the absence of mobility degradation with temperature. These results will give an understanding of this future generation device at both device and circuit levels.

Selective Auto-Reclosing of Mixed Circuits Based on Multi-Zone Differential Protection Principle and Distributed Sensing

Environmental concerns and economic constraints have led to increasing installations of mixed conductor circuits comprising underground cables (UGCs) and overhead transmission lines (OHLs). Faults on the OHL sections of such circuits are usually temporary, while there is a higher probability that faults on UGC sections are permanent. To maintain power system reliability and security, auto-reclose (AR) schemes are typically implemented to minimize outage duration after temporary OHL faults while blocking AR for UGC faults to prevent equipment damage. AR of a hybrid UCG–OHL transmission line, therefore, requires effective identification of the faulty section. However, the different electrical characteristics of UGC and OHL sections present significant challenges to existing protection and fault location methods. This paper presents a selective AR scheme for mixed conductor circuits based on the evaluation of differential currents in multiple defined protection zones, using distributed current transformer (CT) measurements provided by passive optical sensing. Case studies are conducted with a number of different UGC–OHL configurations, and the results demonstrate that the proposed scheme can accurately identify the faulty section, enabling effective selective AR of a comprehensive range of mixed conductor circuit topologies. The proposed scheme is also more cost effective, with reduced hardware requirements compared to conventional solutions. This paper thereby validates the optimal solution for mixed circuit protection as described in CIGRE Working Group B5.23 report 587.

24–35 GHz Filtering LNA and Filtering Switch Using Compact Mixed Magnetic-Electric Coupling Circuit in 28-nm Bulk CMOS

This paper presents compact 24–35 GHz filtering low noise amplifier (LNA) and filtering switch in 28-nm CMOS technology. A compact mixed magnetic-electric coupling circuit is designed, where a transmission zero is introduced out of the passband due to the cancellation of the magnetic and electric couplings. By analyzing the impedance characteristics, this structure can be designed with the impedance conversion function to replace the widely used transformers in integrated circuit designs. It shows the advantages of easy control of coupling coefficient and out-of-band rejection. Then, an LNA employing the magnetic-electric coupling circuits as impedance matching networks is designed. Image rejection can be achieved without increasing the circuit area. Moreover, by loading transistors to this mixed magnetic-electric coupling circuit, the input impedance can be controlled by the parasitic components of the transistor. Subsequently, a filter passband can be switched on and off, realizing a very compact filtering single-pole single-throw (SPST) switch. The fabricated filtering LNA is measured with a 3-dB bandwidth of 24–35 GHz, a noise figure (NF) of 2.4-3.6 dB, a maximum gain of 22 dB, and suppression of better than 25 dBc below 18 GHz. The filtering switch shows a minimum on-state loss of 2.1 dB at 28.6 GHz with better than 12.9 dB rejection below 16 GHz and off-state isolation of higher than 19 dB.

Magnetic Circuit Feature Investigation of a Radial–Axial Brushless Hybrid Excitation Machine for Electric Vehicles

The magnetic circuit feature of a radial–axial brushless hybrid excitation machine (RA-BHEM) is studied in this article. An axial stator is placed on one side of the rotor, which is wound with ac excitation winding to adjust the air-gap flux flexibly to make it have good flux regulation capability. The flux distribution of the RA-BHEM is a radial–axial 3-D mixed magnetic circuit, which is difficult to be analyzed by the 2-D finite-element analysis (FEA). Therefore, a radial–axial equivalent magnetic circuit (RAEMC) model is established to obtain the air-gap flux density with different excitation magnetomotive forces (MMFs), which simplifies the design process and reduces the amount of calculation. The flux density distribution in different MMFs is analyzed by 3-D finite FEA and the results are consistent with the RAEMC model results. The torque characteristics in the low-speed region and the flux-weakening capability in the high-speed region are analyzed to verify the possibility of the proposed machine in the field of electric vehicles (EVs). Finally, a 2-kW prototype is manufactured to verify the correctness of the above analysis.

Can mixed circuit training elicit the recommended exercise intensity and energy expenditure in people after stroke?

ABSTRACT Purpose To investigate whether mixed circuit training (MCT) elicits the recommended exercise intensity and energy expenditure in people after stroke, and to establish the between-day reproducibility for the percentages of heart rate reserve (%HRR), oxygen uptake reserve (%VO2R), and energy expenditure elicited during two bouts of MCT. Methods Seven people aged 58 (12) yr, who previously had a stroke, performed a cardiopulmonary exercise test, a non-exercise control session, and two bouts of MCT. The MCT included 3 circuits of 10 resistance exercises at 15-repetition maximum intensity, with each set of resistance exercise interspersed with 45-s of walking. Expired gases were collected during the MCT and control session and for 40 min afterward. Control session was necessary to calculate the net energy expenditure associated with each bout of MCT. Results Mean %VO2R (1st MCT: 51.1%, P = .037; 2nd MCT: 54.0%, P = .009) and %HRR (1st MCT: 66.4%, P = .007; 2nd MCT: 67.9%, P = .010) exceeded the recommended minimum intensity of 40%. Both %VO2R (P = .586 and 0.987, respectively) and %HRR (P = .681 and 0.237, respectively) during the 1st and 2nd bouts of MCT were not significantly different to their corresponding gas exchange threshold values derived from cardiopulmonary exercise testing. Mean net total energy expenditure significantly exceeded the minimum recommend energy expenditure in the 1st (P = .048) and 2nd (P = .023) bouts of MCT. Between-day reproducibility for %HRR, %VO2R, and energy expenditure was excellent (ICC: 0.92–0.97). Conclusions MCT elicited physiological strain recommended for improving health-related fitness in people after stroke and these responses demonstrated excellent between-day reproducibility.

Compact single‐ and dual‐band band‐pass filters employing mixed eighth‐mode substrate‐integrated waveguide and microstrip line resonators

In this study, single- and dual-band band-pass filters (BPFs) employing mixed eighth-mode substrate-integrated waveguide (EMSIW) and microstrip line (MSL) resonators are proposed and investigated. The mixed resonators feature compact circuit size, moderate quality factor and flexible design topology. By exploiting the mixed resonators to implement the BPF designs, a single-band BPF is developed, exhibiting four-order broadband band-pass filtering responses in a single-layered substrate. Several transmission zeros are introduced near the working passband to enhance the frequency selectivity. Moreover, the proposed BPF has the capability to suppress the harmonics superior to 20 dB rejection level up to 2.36 f0. Meanwhile, two dual-band BPFs are designed in double-layered substrates with magnetic and electric coupling schemes. Both dual-band BPFs exhibit compact circuit size and low insertion loss. To the best of the authors' knowledge, it is the first time to develop single- and dual-band BPFs based on mixed EMSIW and MSL resonators in this study. For demonstration, a series of single- and dual-band BPFs with mixed SIW/MSL resonators are developed and fabricated. The simulated, measured and synthesised results have reached satisfactory agreements.

Mixed circuit training acutely reduces arterial stiffness in patients with chronic stroke: a crossover randomized controlled trial.

Investigate whether a single bout of mixed circuit training (MCT) can elicit changes in arterial stiffness in patients with chronic stroke. Second, to assess the between-day reproducibility of post-MCT arterial stiffness measurements. Seven participants (58 ± 12years) performed a non-exercise control session (CTL) and two bouts of MCT on separate days in a randomized counterbalanced order. The MCT involved 3 sets of 15 repetition maximum for 10 exercises, with each set separated by 45-s of walking. Brachial-radial pulse wave velocity (br-PWV), radial artery compliance (AC) and reflection index (RI1,2) were assessed 10min before and 60min after CTL and MCT. Ambulatory arterial stiffness index (AASI) was calculated from 24-h recovery ambulatory blood pressure monitoring. Compared to CTL, after 60min of recovery from the 1st and 2nd bouts of MCT, lower values were observed for br-PWV (mean diff = -3.9 and -3.7m/s, respectively, P < 0.01; ICC2,1 = 0.75) and RI1,2 (mean diff = -16.1 and -16.0%, respectively, P < 0.05; ICC2,1 = 0.83) concomitant with higher AC (mean diff = 1.2 and 1.0 × 10-6cm5/dyna, respectively, P < 0.01; ICC2,1 = 0.40). The 24-h AASI was reduced after bouts of MCT vs. CTL (1st and 2nd bouts of MCT vs. CTL: mean diff = -0.32 and -0.29 units, respectively, P < 0.001; ICC2,1 = 0.64). A single bout of MCT reduces arterial stiffness during laboratory (60min) and ambulatory (24h) recovery phases in patients with chronic stroke with moderate-to-high reproducibility. Ensaiosclinicos.gov.br identifier RBR-5dn5zd.

Verification of intrinsic safety on instrumentation loop

AbstractIntrinsic safety is one of the explosion protection techniques implemented in an industry where a flammable substance is present. It is a technique that reduces the electrical energy level at the hazardous area below the ignition curve so that it is not sufficient to initiate an explosion. In addition to limiting the energy to the field, the energy stored in the circuit and thermal ignition due to hot surfaces in hazardous areas must also be considered. Intrinsically safe is the preferred explosion protection method for instrumentation and control signals as it allows live maintenance, the use of an uncertified simple apparatus, and is applicable to all Zones. All intrinsically safe circuits must carry out a safety assessment and verify their compliance with intrinsic safety before implementation to avoid explosion. The verification process could be complex for mixed circuits and non‐simple intrinsically safe systems; moreover, there has been much confusion for many years until the 4th Edition of the installation standard, IEC 60079‐14, provided a clearer picture. This paper carries out an intrinsic safety verification assessment on a mixed circuit involving surge protection devices according to IEC and NEC standards. It also highlights the common mistake made by system designers when verifying the safety parameters.

Research on Interruption Performance of Environmentally Friendly C4F7N Mixed-Gas-Insulated Switchgear

SF6, which is currently widely used in gas-insulated power transmission equipment, is a greenhouse gas with a very strong greenhouse effect. Therefore, developing environmentally friendly gas insulation equipment to gradually reduce the use of SF6 has become a hot research topic. As the most potential alternative gas, C4F7N is of great significance to study the electrical characteristics of the medium-voltage switching field to promote the green development of the power industry. Based on multi-physical field coupling to construct the 40.5 kV circuit breaker mode, this paper uses C4F7N/CO2 mixed gas to compare and study the dynamic characteristics of a C4F7N/CO2 mixed gas circuit breaker when breaking the short-circuit current and the dielectric recovery strength with no-load breaking, as well as to evaluate the electrical performance of C4F7N mixed gas in a 40.5 kV breaker with the gas breakdown criterion. The results show that mixing O2 in a high current can improve the breaking performance of an environmental protection circuit breaker and increasing the C4F7N mass fraction can enhance the dielectric recovery strength of the environmentally friendly circuit breaker. Considering the overall performance of the gas, the 5%C4F7N/90% CO2/5%O2 mixed gas has some alternative potential.

CuInS2/TiO2 heterojunction with elevated photo-electrochemical performance for cathodic protection

Semiconductor quantum dots with high quantum yield and photovoltaic conversion efficiency have ushered in a brilliant moment for constructing internal electric field heterojunctions for photogenerated cathodic protection applications. In this paper, TiO2 nanotubes grown vertically on the surface of titanium substrates were modified via a combination of conventional electrochemical oxidation and a one-step solvothermal pathway to sensitize with CuInS2 quantum dots. Compared with pure TiO2 photoelectrodes, the modification improves sunlight absorption efficiency and provides photoelectron cathodic protection to the 304 stainless steel (304 SS). Through 9 h solvothermal reaction, the CuInS2/TiO2 coupled with protected 304 SS exhibited an excellent property when the simulated sunlight irradiation. Its mixed open circuit potential is negatively shifted to -0.99 V, at the mean time with a stable photocurrent density (118 μA cm−2). The results indicate that CuInS2 and TiO2 established a p-n heterojunction with well-matched energy level, which can effectively facilitate the carrier separation and retain the strong redox capbility of photo-induced electrons and holes.

A Wideband SICL-to-Waveguide Transition for Multilayer Planar Circuit Applications at V-Band

A <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V$ </tex-math></inline-formula> -band substrate integrated coaxial line (SICL) to rectangular waveguide (RWG) transition is proposed in this letter. In this design, a folded dipole is used to achieve a more compact structure and better impedance matching in the operating band. Compared with other transitions based on single-layer substrates, this design is more suitable for mixed multilayer circuits. For verification, a back-to-back transition prototype is fabricated by standard multilayer printed circuit boards processing and measured. The measured results show that the proposed transition has a wide −10-dB impedance bandwidth of 40% (from 50 to 75 GHz), and an insertion loss of lower than 4 dB over the operating bandwidth. Owing to compact size and wide operating bandwidth, the proposed transition is valuable to advanced millimeter-wave (mmW) circuit systems.

Analysis of Flux Density and Iron Loss Distributions in Segmented Magnetic Circuits Made With Mixed Electrical Steel Grades

This article presents the potential contribution of segmented stator magnetic circuits of rotating permanent magnet electrical machines with concentric winding. Two magnetic materials are mixed: FeSi non-oriented electrical steel and FeSi grain-oriented electrical steel (GOES). The choice of using GOES is based on the high performance it offers in terms of permeability and iron losses compared to conventional non-oriented grain electrical steel (NOES), particularly when GOES is magnetized in the rolling direction (RD). The goal is to analyze the contribution of the mixed magnetic circuit on the losses and electromagnetic torque but also the drawbacks due to the cut process and the assembly. The behavior of the magnetic field at the junction between the segments is studied by comparing different geometrical connection shapes and compared to a reference magnetic circuit fully made with NOES sheets. This comparison is experimentally made with a model representative of the existing phenomena in an electrical machine. In addition, numerical calculations using finite elements software are carried out by considering both the magnetic anisotropy and the saturation of the GOES.

Acute effects of mixed circuit training on hemodynamic and cardiac autonomic control in chronic hemiparetic stroke patients: A randomized controlled crossover trial.

Objectives: To investigate whether a single bout of mixed circuit training (MCT) can elicit acute blood pressure (BP) reduction in chronic hemiparetic stroke patients, a phenomenon also known as post-exercise hypotension (PEH). Methods: Seven participants (58 ± 12 years) performed a non-exercise control session (CTL) and a single bout of MCT on separate days and in a randomized counterbalanced order. The MCT included 10 exercises with 3 sets of 15-repetition maximum per exercise, with each set interspersed with 45 s of walking. Systolic (SBP) and diastolic (DBP) blood pressure, mean arterial pressure (MAP), cardiac output (Q), systemic vascular resistance (SVR), baroreflex sensitivity (BRS), and heart rate variability (HRV) were assessed 10 min before and 40 min after CTL and MCT. BP and HRV were also measured during an ambulatory 24-h recovery period. Results: Compared to CTL, SBP (∆-22%), DBP (∆-28%), SVR (∆-43%), BRS (∆-63%), and parasympathetic activity (HF; high-frequency component: ∆-63%) were reduced during 40 min post-MCT (p < 0.05), while Q (∆35%), sympathetic activity (LF; low-frequency component: ∆139%) and sympathovagal balance (LF:HF ratio: ∆145%) were higher (p < 0.001). In the first 10 h of ambulatory assessment, SBP (∆-7%), MAP (∆-6%), and HF (∆-26%) remained lowered, and LF (∆11%) and LF:HF ratio (∆13%) remained elevated post-MCT vs. CTL (p < 0.05). Conclusion: A single bout of MCT elicited prolonged PEH in chronic hemiparetic stroke patients. This occurred concurrently with increased sympathovagal balance and lowered SVR, suggesting vasodilation capacity is a major determinant of PEH in these patients. This clinical trial was registered in the Brazilian Clinical Trials Registry (RBR-5dn5zd), available at https://ensaiosclinicos.gov.br/rg/RBR-5dn5zd. Clinical Trial Registration: https://ensaiosclinicos.gov.br/rg/RBR-5dn5zd, identifier RBR-5dn5zd

Performance analysis of linear permanent magnet Vernier machine using mixed subdomain and magnetic equivalent circuit techniques including end‐effect

Performance analysis of a linear permanent magnet Vernier machine (LPMVM), which has a complex structure, is mostly based on the finite element methods, while for its optimisation or sensitivity analysis a quick mathematical technique is desirable. This paper introduces an LPMVM and its principles of operation. Then, a mixed subdomain and magnetic equivalent circuit are applied to extract magnetic field equations in various parts of the machine, in which the end-effect in included. Besides, the electromotive force, thrust force, normal force and electric equivalent circuit are determined. An LPMVM was prototyped and tested to verify the accuracy of the proposed method.

Key Technology of Mixed Matching Circuit for Miniaturizing Dual-Band Antenna

A mixed matching circuit for miniaturizing dual-band antenna is introduced and verified in this paper. According to the dual-band allocations on the Smith chart, two L-shaped matching circuit for miniaturization are cascaded to interpret the theory of operation. A matching circuit formula is deduced based on a bidirectional matching track from a certain position to the origin point on the Smith chart. Furthermore, a dual-band antenna is taken as an example to illustrate the performance of the novel matching approach for miniaturization. The occupation of a dual-band antenna can be reduced by a quarter at the simultaneous operational frequencies of 2.4 and 5.8 GHz. Finally, a dual-band planar inverted-F antenna (PIFA) is fabricated and measured. The experimental results have a good agreement with those in the simulator.