Circuit Simulation Research Articles

Design and Signal-Decoding Test Verification of Dual-Channel Round Inductosyn Decoding Circuit

During the in-orbit operation of spacecraft, permanent magnet synchronous motors are commonly used as power sources in the drive mechanisms of solar panel arrays and the high-precision servo control systems based on satellites. Apart from the performance of the motors themselves and the software control algorithms, the accuracy of the entire control system is also influenced by angle sensors used to detect the rotor position of the motors. As a high-precision angular measuring instrument, the inductosyn possesses excellent environmental adaptability and long service life. Effectively utilizing the inductosyn can greatly enhance the performance of servo control systems. To address the complexity of the decoding process for dual-channel round inductosyn-to-digital converters, this paper proposes a design of the decoding circuit for dual-channel round inductosyn based on the parallel-synchronization decoding method of two AD2S1210 Resolver-to-Digital Converter (RDC) decoding chips. The decoding circuit amplifies the excitation signal outputted by the AD2S1210 for driving the round inductosyn, and processes the sine and cosine induction signals outputted by the round inductosyn through filtering, amplification, and other methods; by using analog circuitry, the output signals of the dual-channel round inductosyn are processed to meet the input requirements of the AD2S1210. Finally, through both the Multisim (circuit simulation software Version 14.1) simulation and physical experiments, it was verified that the decoding circuit designed in this paper could process the input/output signals of the dual-channel round inductosyn and AD2S1210, and successfully decoded the analog induction signal of the round inductosyn. This greatly simplifies the signal decoding process for the dual-channel round inductosyn.

NUMA-aware parallel sparse LU factorization for SPICE-based circuit simulators on ARM multi-core processors

In circuit simulators that resemble the Simulation Program with Integrated Circuit Emphasis (SPICE), one of the most crucial steps is the solution of numerous sparse linear equations generated by frequency domain analysis or time domain analysis. The sparse direct solvers based on lower-upper (LU) factorization are extremely time-consuming, so their performance has become a significant bottleneck. Despite the existence of some parallel sparse direct solvers for circuit simulation problems, they remain challenging to adapt in terms of performance and scalability in the face of rapidly evolving parallel computers with multiple NUMA hardware based on ARM architecture. In this paper, we introduce a parallel sparse direct solver named HLU, which re-examines the performance of the parallel algorithm from the viewpoint of parallelism in pipeline mode and the computing efficiency of each task. To maximize task-level parallelism and further minimize the thread waiting time, HLU devises a fine-grained scheduling method based on an elimination tree in pipeline mode, which employs depth-first search (DFS-like) to iteratively search for parent tasks and then place dependent tasks in the same task queue. HLU also suggests two NUMA node affinity strategies: thread affinity optimization based on NUMA nodes topology to guarantee computational load balancing and data affinity optimization to enable effective memory placement when threads access data. The rationality and effectiveness of the sparse solver HLU are validated by the SuiteSparse Matrix Collection. In comparison with KLU and NICSLU, the experimental results and analysis show that HLU attains a speedup of up to 9.14× and 1.26x (geometric mean) on a Huawei Kunpeng 920 Server, respectively.

High-fidelity Remote Entanglement between Superconducting Fixed-frequency Qubits

Abstract Highly accurate quantum state transfer and remote entanglement between superconducting fixed-frequency qubits have not yet been realized. In this study, we characterize a transmission path with a 1- or 0.25-m superconducting coaxial cable and use the characteristics to perform time evolution simulations of quantum state transfer and remote entanglement between superconducting fixed-frequency qubits. We find that remote entanglement, or half-quantum state transfer, can achieve a high fidelity > 99% even in the presence of a qubit frequency detuning caused by manufacturing fluctuations, while a small qubit frequency detuning substantially reduces the efficiency of quantum state transfer. Quantum circuit simulations modeling proposed remote entanglement demonstrate that teleportation of a logical qubit with a 3 × 3 surface code, as an example of computation using remote entanglement, attains nearly the same fidelity as in-node computation for both 1- and 0.25-m cable lengths.

The Accuracy of the Titan 1+ 10 Hz Global Positioning System for Measures of Time, Distance, and Top Speed

Introduction: Global Positioning System (GPS) technology provide quantifiable data concerning the number and types of movements athletes complete across training session and match player. The Titan 1+ is a novel GPS device that has not been investigated to establish measures of accuracy or reliability. The purpose of this study was to establish device accuracy for metrics including distance, top speed, and time between the Titan 1+ 10 Hz GPS device and criterion measures. Criterion measures include tape measure, stopwatch, and radar gun for measures of distance, time, and top speed, respectively. Methods and Materials: 16 male NCAA collegiate soccer players completed running protocols of varying distances and speeds, including long and short duration straight-line running (100m Run and SLR), tight and gradual change of direction running (COD T and COD G), and a team-sport simulated circuit. Results: The Titan 1+ was not significantly different from tape measured distance during the SLR protocol for 10m jog and all movements speed across 20m and 40m (p < .05). The Titan 1+ was significantly correlated to radar gun top speed measures for all distances and movement speeds during the SLR (p < .01). The Titan 1+ was significantly different from the stopwatch for measures of time accuracy (p < .0001), however significant correlations were identified for all jogging distances (p < .01), the 20m and 40m strides (p < .01), and the 10m sprint (p < .01). COD G and COD T distances were accurately measured between the Titan 1+ and tape measure (p < .05). The Titan 1+ revealed correlations for time measures during jogging and striding during the COD G (p = .001 and p < .0001) and during the COD T (p < .0001 and p< .0001). Device accuracy was established for measure of time during the TSSC (p < .05), with time measures significantly correlated between the Titan 1+ and stopwatch (p < .01). Top speed for the TSSC was significantly different between the radar gun and Titan 1+ device (p = .001), but both devices were significantly correlated (p < .01). Conclusions: The results of the present study indicate that the Titan 1+ demonstrates accurate measures of time, distance, and top speed when compared to criterion measures.

Stochastic Memristor Modeling Framework Based on Physics-Informed Neural Networks

In this paper, we present a framework of modeling memristor noise for circuit simulators using physics-informed neural networks (PINNs). The variability of the memristor that is directly related to the neuromorphic system can be handled with this approach. The memristor noise model is transformed into a Fokker–Planck equation (FPE) from a probabilistic perspective. The translated equations are physically interpreted through the PINN. The weights and biases extracted from the PINN are implemented in Verilog-A through simple operations. The characteristics of the stochastic system under the noise are obtained by integrating the probability density function. This approach allows for the unification of different memristor models and the analysis of the effects of noise.

Characteristics of oxide films on TA16 alloy after long-term exposure in simulated secondary circuit water environment of small modular reactor

Currently, little is known about the characteristics of oxide films on Ti alloys exposed to the secondary circuit water environment of small modular reactors (SMRs). In this study, multiple microstructural characterization techniques were employed to meticulously characterize the oxide film characteristics of the TA16 alloy after 6000 h and 8000 h of exposure to a simulated SMR secondary circuit water environment. The results indicate that the oxide films on the 6000 h specimen are composed of a microcrystalline anatase TiO2 interior layer and a coarse-grained anatase TiO2 exterior layer, while the oxide film on the 8000 h specimen typically consists of a microcrystalline anatase TiO2 inner layer, an NiFe2O4 middle layer, and a coarse-grained anatase TiO2 outer layer. As the corrosion time is extended to 8000 h, the presence of NiFe2O4 oxide particles can be attributed to oxide deposition by the 316L stainless steel autoclave used in the corrosion experiments, which results in the migration of Ni and Fe ions onto the surface of the Ti alloy.

Observing Quantum Measurement Collapse as a Learnability Phase Transition

During a quantum measurement, superpositions of states with different observable properties probabilistically collapse into one with a sharp value of the measured observable. In macroscopic quantum systems, this collapse arises via a continuous measurement-induced phase transition (MIPT) at a critical value of the strength of interaction with the measurement apparatus. MIPTs lie outside established paradigms for equilibrium or nonequilibrium critical phenomena and delineate distinct, stable dynamical and computational phases of matter. Quantum computers enable programmable simulation of the interaction of a measurement apparatus with a dynamical quantum system, to explore MIPT phenomena over a range of system sizes while retaining quantum coherence. Yet, existing experimental protocols rely on fundamentally nonscalable postselection techniques or direct classical simulation of quantum circuits. Here, we report the scalable observation of finite-size scaling evidence for an observable-sharpening MIPT in monitored quantum circuits in a chain of Yb+171 ions in Quantinuum’s H1-1 trapped-ion quantum processor. By leveraging an equivalent description as a statistical physics problem, we implement scalable classical algorithms to infer the value of the measured observable from a single experimental shot. This technique enables a truly scalable protocol to observe observable-sharpening MIPTs in generic classes of circuits that cannot be directly classically simulated and also provides enhanced means to detect and suppress errors in the quantum simulation. Published by the American Physical Society 2024

Efficient memristor accelerator for transformer self-attention functionality

The adoption of transformer networks has experienced a notable surge in various AI applications. However, the increased computational complexity, stemming primarily from the self-attention mechanism, parallels the manner in which convolution operations constrain the capabilities and speed of convolutional neural networks (CNNs). The self-attention algorithm, specifically the matrix-matrix multiplication (MatMul) operations, demands a substantial amount of memory and computational complexity, thereby restricting the overall performance of the transformer. This paper introduces an efficient hardware accelerator for the transformer network, leveraging memristor-based in-memory computing. The design targets the memory bottleneck associated with MatMul operations in the self-attention process, utilizing approximate analog computation and the highly parallel computations facilitated by the memristor crossbar architecture. Remarkably, this approach resulted in a reduction of approximately 10 times in the number of multiply-accumulate (MAC) operations in transformer networks, while maintaining 95.47% accuracy for the MNIST dataset, as validated by a comprehensive circuit simulator employing NeuroSim 3.0. Simulation outcomes indicate an area utilization of 6895.7 μm2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu m^2$$\\end{document}, a latency of 15.52 seconds, an energy consumption of 3 mJ, and a leakage power of 59.55 μW\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu W$$\\end{document}. The methodology outlined in this paper represents a substantial stride towards a hardware-friendly transformer architecture for edge devices, poised to achieve real-time performance.

Regulation and analysis of multi-scroll attractors in a class of memristive Hopfield neural networks with high Lyapunov exponents

Multi-scroll chaotic systems have gained significant attention in recent years. However, there is little research on the chaotic systems of memristive neural networks with multiple complex structural attractors. A class of multi-scroll chaotic systems are designed in this paper, which are based on Hopfield neural network by using memristors as synapses. Implementing synaptic control with memristors at various coupling positions allows for the creation of multiple chaotic attractors with distinct topological structures. The proposed systems exhibit special and irregular shaped attractors, and can generate a fixed number of scrolls. Through analysis we find that the systems have high Lyapunov exponents, indicating strong sensitivity and randomness. Meanwhile, the systems exhibit extremely rich dynamic behaviors, such as symmetric coexistence phenomena. Especially, we observe signal amplitude control and offset boosting phenomena in the systems. In addition, simulation circuits are designed based on such chaotic systems to verify the physical feasibility of the systems.

ResNet Modeling for 12 nm FinFET Devices to Enhance DTCO Efficiency

In this paper, a deep learning-based device modeling framework for design-technology co-optimization (DTCO) is proposed. A ResNet surrogate model is utilized as an alternative to traditional compact models, demonstrating high accuracy in both single-task (I–V or C–V) and multi-task (I–V and C–V) device modeling. Moreover, transfer learning is applied to the ResNet model, using the BSIM-CMG compact model for a 12 nm FinFET SPICE model as the pre-trained source. Through this approach, superior modeling accuracy and faster training speed are achieved compared to a ResNet surrogate model initialized with random weights, thereby meeting the rapid and efficient demands of the DTCO process. The effectiveness of the ResNet surrogate model in circuit simulation for 12 nm FinFET devices is demonstrated.

Multi-objective simulated annealing-based quantum circuit cutting for distributed quantum computation

In the current noisy intermediate-scale quantum (NISQ) era, the number of qubits and the depth of quantum circuits in a quantum computer are limited because of complex operation among increasing number of qubits, low-fidelity quantum gates under noise, and short coherence time of physical qubits. However, with distributed quantum computation (DQC) in which multiple small-scale quantum computers cooperate, large-scale quantum circuits can be implemented. In DQC, it is a key step to decompose large-scale quantum circuits into several small-scale subcircuits equivalently. In this paper, we propose a quantum circuit cutting scheme for the circuits consisting of only single-qubit gates and two-qubit gates. In the scheme, the number of non-local gates and the rounds of subcircuits operation are minimized by using the multi-objective simulated annealing (MOSA) algorithm to cluster the gates and to choose the cutting positions whilst using non-local gates. A reconstruction process is also proposed to calculate the probability distribution of output states of the original circuit. As an example, the 7-qubit circuit of Shor algorithm factoring 15 is used to verify the algorithm. Five cutting schemes are recommended, which can be selected according to practical requirements. Compared with the results of the mixing integer programming (MIP) algorithm, the number of execution rounds is efficiently reduced by slightly increasing the number of nonlocal gates.

A color image encryption algorithm based on a novel 4D hyperchaotic system and bit-level diffusion

As digital images are widely used in social media, medical, military and other fields, ensuring the privacy and security of image data has become a critical concern. Firstly, we propose a novel four-dimensional hyperchaotic system and validate that it exhibits a broad chaotic range, as demonstrated by bifurcation diagrams and Lyapunov exponent experiments. Additionally, simulated circuit diagrams verify the hardware feasibility of the proposed system. Secondly, we design a dynamic iterative scrambling (DIS) scheme that dynamically divides the image into multiple matrices for spatially indexed scrambling. Excellent substitution performance can be ensured by multiple iterations. In the diffusion stage, a multidirectional bit-level L-shaped (MDBL) scheme is proposed. Diffusion is conducted on the bit plane using a designed cross-multiplanar selection algorithm, which fuses the high and low bit planes, thereby enhancing the diffusion performance of MDBL. Thirdly, Based on the above concepts, a novel four-dimensional hyperchaotic system and an encryption algorithm based on bit-level diffusion are proposed. Finally, experimental results and security analyses demonstrate the effectiveness of the novel 4D hyperchaotic system and image encryption scheme. The proposed encryption scheme exhibits robust anti-interference capabilities and effectively safeguards image security.

A planar three-section coupled-line high-selectivity wideband bandstop filter

A planar three-section coupled-line high-selectivity wideband bandstop filter (BSF) is proposed. The proposed filter topology contains three coupled-line sections (CLs) and two transmission-line sections (TLs). The four locations of transmission zeros (TZs) are obtained through the deduction of the theoretical equations, which validates the proposed topology. During circuit simulation, the effect of the Z e1 on the skirt roll-off is investigated. A highly selective wideband BSF with center frequency at 2.4 GHz, rejection level below 20 dB and attenuation rate at 278.69 dB/GHz is designed and manufactured. The theoretical and simulation results are in good agreement. Indeed, it illustrates the correctness of the theoretical analysis.

Extreme multi-stability and circuit implementation for a two-ReLU-memristor-based jerk oscillator

Memristor-based oscillation circuits are prone to produce coexisting infinite attractors depending on the initial conditions of memristors, leading to the appearance of extreme multi-stability. In this paper, we propose a novel memristive jerk oscillator by bringing two ReLU-type memristors in a simple jerk oscillator and investigate its dynamical behaviors associated with the coupling parameters using bifurcation plots and Lyapunov exponent plots. Further, we discuss the planar equilibrium state and its stability, and then numerically explore the coexisting infinite attractors driven by the initial conditions of two ReLU-type memristors. Because of the intervention of the two ReLU-type memristors, the memristive jerk oscillator has a planar equilibrium state whose stability closely relies on the initial conditions of two ReLU-type memristors, and different initial conditions cause different attractors to coexist, resulting in bidirectional extreme multi-stability. Finally, the memristive jerk oscillator is implemented by analog circuit and digital hardware platform, and the numerical results are confirmed by circuit simulations and hardware experiments.

The influence of equilibrium points and initial values on multistability of a multi-scroll chaotic system and predefined-time synchronization

Abstract In order to explore the effect of the initial value on the symmetry of the coexisting attractor, a novel multi-scroll chaotic system is designed in this paper. The system is proved to be chaotic by analysing the phase diagram, Lyapunov exponential spectrum and dissipativity of the system. Then the equilibrium point of the system is investigated and it is found that the system has four symmetric saddle focus of index 2. By analysing the dynamical behaviour of the system, it is found that the system has a special kind of multistability. Combining the properties of the orbits near the saddle focus of indicator 2, the reason for this special multistability is explained, and the effect of the positional relationship between the initial value and the saddle focus on the symmetry of the coexisting attractors is illustrated, which provides a new way of thinking to analyse the symmetric coexistence of chaotic systems. In order to verify the feasibility and application value of the system, simulation circuits are designed and predefined-time synchronization between systems of different dimensions is achieved.

Design and analysis of low-profile quad element wide band MIMO antenna with efficient isolation for C and X-band applications

ABSTRACT A low-profile, quad-element multiple-input/multiple-output (MIMO) antenna of 0.69 λ 0 λ 0 is presented in this study. The proposed design consists of a stub and slot-loaded partial ground plane with a quad rectangular-shaped radiator on top. The four elements are placed orthogonally to one another to reduce mutual coupling and envelope correlation coefficient (ECC). The maximum isolation of the proposed MIMO antenna is 61.5 dB at 9.94 GHz frequency. It achieved impedance bandwidth 5.56 GHz, ranging from 5.74–11.30 GHz. The peak gain of the proposed MIMO antenna is 6.18 dB at 7.3 GHz, with a maximum efficiency of 89.21% at 7.1 GHz. The minimum ECC between ports 1 and 2 over the operating band are observed as 0.0001. To achieve the best outcome, a parametric analysis of the proposed antenna is also performed. Various diversity characteristic metrics, including diversity gain (DG), mean effective gain (MEG), total active reflection coefficient (TARC), channel capacity loss (CCL), and ergodic channel capacity (CC), are thoroughly analysed to determine how well the MIMO antenna performs in terms of diversity. Over the operating band, the measured values provide good agreement with respect to simulated and equivalent circuit model results, indicating a strong candidacy for operation in the investigated bands. The proposed MIMO antenna have the potential for C and X band applications such as WLAN, radio astronomy, satellite communication, and automotive radar.

Consensus Control of Leader–Follower Multi-Agent Systems with Unknown Parameters and Its Circuit Implementation

With the development and progress of Internet and data technology, the consensus control of multi-agent systems has been an important topic in nonlinear science. How to effectively achieve the consensus of leader–follower multi-agent systems at a low cost is a difficult problem. This paper analyzes the consensus control of complex financial systems. Firstly, the dynamic characteristics of the financial system are analyzed by the equilibrium points, bifurcation diagrams, and Lyapunov exponent spectra. The behavior of the financial system is discussed by different parameter values. Secondly, according to the Lyapunov stability theorem, the consensus of master–slave systems is proposed by linear feedback control, wherein the controllers are simple and low cost. And an adaptive control method for the consensus of master–slave systems is investigated based on financial systems with unknown parameters. In theory, the consensus of the leader–follower multi-agent systems is proved by the parameter identification laws and linear feedback control method. Finally, the effectiveness and reliability of the consensus of leader–follower multi-agent systems are verified through the experimental simulation results and circuit implementation.

A Comparative Study on Picoammeter Designs as Alternatives for Nuclear Reactor Power Measurement Systems

Abstract The study investigates the picoammeter, a highly sensitive current measurement device capable of measuring currents in the picoampere (pA) range. It discusses the typical amplification technique in picoammeters, utilizing an Op-Amp in a trans-impedance amplifier (TIA) circuit to convert the current into a voltage signal. The paper explores the impact of different IC Op-Amps on the picoammeter’s performance, evaluating AD549, MAX4230, LMC662, TLV272, and MCP6001. The result reveals that AD549 Op-Amp ICs are more suitable for picoammeter design due to their low noise performance and low input bias current. Noise output and AC stability are assessed through numerical analysis and simulations using a circuit simulator. The resulting picoammeter exhibits low noise, high sensitivity, and precise measurement accuracy, making it an optimal choice for precise low-current measurements in CIC detectors.

High-pressure core meltdown and hydrogen generation during In-vessel and Ex-vessel phases of VVER-1000 nuclear reactor and effect of heat structures

Following unprecedented Fukushima Daiichi severe accident, which significantly amplify the production of hydrogen and the associated risk of explosions, particularly in accidents like station blackout (SBO) that jeopardize containment integrity and reactor safety, a thorough investigation and comprehension of the phenomenon known as high-pressure melt ejection (HPME) are necessary. This study examines how the SBO accident develops without operator intervention or access to emergency diesel generators through full nuclear power plant simulation, including containment, core, primary, and secondary circuits. Accurate time step selection is crucial for the simulation to produce reliable results for high-pressure melt ejection processes. While the process is faster and easier under Low Pressure Melt Ejection (LPME) conditions, time step tuning can significantly lengthen the (HPME) simulation (approximately one month for each scenario). After thorough examinations and analysis of various simulation findings, three cases were evaluated for the ex-vessel phase, illustrating the most likely scenarios of high-pressure molten material splashing into the cavity. The findings demonstrate that during the in-vessel phase, 578 kg of hydrogen is created. Additionally, during the ex-vessel phase, there is a significant increase in the containment’s temperature and pressure due to the high-temperature hydrogen and significant water and steam leakage. The temperature and pressure inside the containment rise well above the safety criteria due to the leakage of 1529 kg of hydrogen from the cavity and lead to hydrogen explosion due to MELCOR message. The calculated amount of hydrogen gas is within the explosion limit range of 18.3% to 59% of the containment atmospheric pressure volume. Moreover, the height and diameter of the cavity alter due to the direct heating and corrosion of the cavity walls, ultimately compromising the integrity of the plant in the alpha mode. Based on the results obtained, it can be seen that if a large portion of the molten material is deposited on the concrete surface (case III) instead of dispersed in the cavity atmosphere (case I), the rate of hydrogen production and therefore the total amount of hydrogen (and its related energy) produced will be increased and could lead to deflagration to detonation situation.

Design of Power Dividers for Finite Dipole Subarrays with Complex Impedances

In this study, we propose a method for designing a feeding network for all port-matched and high gain dipole subarray antennas excited by uniform current mode (UCM) by considering the mutual coupling effect. By analyzing the array impedance matrix, we first calculated the active input impedance and the required excitation power. Following this, we transformed and combined the complex impedances using the proposed power divider, thus preserving the required excitation power. The design process and results of this study are demonstrated stepwise through circuit simulation. Subsequently, we fabricated and evaluated the proposed subarrays. The impedance matching performance of the UCM was found to be better than that of the conventional subarray, with their array gains being 11.5 dBi and 9.8 dBi, respectively.