Circuit System Research Articles

Development of a high temperature and high pressure downhole string dynamic load monitor

Due to the uncertainty of the formation and the complexity of downhole tubular string loads and deformations, the existing tubular string static theory is difficult to explain and lacks support from measured data of tubular string dynamic loads. Therefore, a dynamic loads monitor for oil and gas tubular string is developed, which can synchronously measure the internal pressure, external pressure, axial force, and vibration acceleration for the string during the whole operation process. The monitor realizes simultaneous monitoring of tubular string load and vibration response parameters while meeting the requirements of various sensor placement spaces and structural strength safety, simplifying the on-site test process. By adding a power control circuit to the circuit system, the working time of the monitor is extended. The high temperature calibration test of the monitor is carried out, and the maximum calibration error is 0.10%, which meets the requirements of measurement accuracy.

Mean square exponential stability with l2−l∞ gain of discrete-time switched-Markovian jump systems

In this paper, the problem of mean square exponential stability with [Formula: see text] gain is studied for the discrete-time switched-Markovian jump systems, which are composed of a deterministic switched system and a Markovian jump system. The mode-dependent average dwell time method is adopted to design the switching signal for the deterministic switched system, and the Markovian jump property is presented by the Markov chain, which is dependent on the designed mode-dependent average dwell time switching signal. The multiple discontinuous Lyapunov function is constructed to guarantee the mean square exponential stability and [Formula: see text] performance. Furthermore, a novel inequality is established to show the relationship between multiple discontinuous Lyapunov functions and disturbances to derive the [Formula: see text] performance. Finally, two numerical examples and a circuit system are given to demonstrate the effectiveness of the obtained results.

Analyzing Various Structural and Temperature Characteristics of Floating Gate Field Effect Transistors Applicable to Fine-Grain Logic-in-Memory Devices.

Although the von Neumann architecture-based computing system has been used for a long time, its limitations in data processing, energy consumption, etc. have led to research on various devices and circuit systems suitable for logic-in-memory (LiM) computing applications. In this paper, we analyze the temperature-dependent device and circuit characteristics of the floating gate field effect transistor (FGFET) source drain barrier (SDB) and FGFET central shallow barrier (CSB) identified in previous papers, and their applicability to LiM applications is specifically confirmed. These FGFETs have the advantage of being much more compatible with existing silicon-based complementary metal oxide semiconductor (CMOS) processes compared to devices using new materials such as ferroelectrics for LiM computing. Utilizing the 32 nm technology node, the leading-edge node where the planar metal oxide semiconductor field effect transistor structure is applied, FGFET devices were analyzed in TCAD, and an environment for analyzing circuits in HSPICE was established. To seamlessly connect FGFET-based devices and circuit analyses, compact models of FGFET-SDB and -CSBs were developed and applied to the design of ternary content-addressable memory (TCAM) and full adder (FA) circuits for LiM. In addition, depression and potential for application of FGFET devices to neural networks were analyzed. The temperature-dependent characteristics of the TCAM and FA circuits with FGFETs were analyzed as an indicator of energy and delay time, and the appropriate number of CSBs should be applied.

Non-smooth finite-time adaptive stabilisation of cascade switched systems with asymmetric output constraints

In this article, the problem of non-smooth finite-time (FT) adaptive state feedback stabilisation is investigated for asymmetric output-constrained cascade switched nonlinear systems (AOCCSNSs) with mixed powers, parametric uncertainties and zero dynamics. To better address the uncertain parameters and the asymmetric output constraints, a new type of common Lyapunov function (CLF) including a quadratic squared term of the estimated error and a tangent-type barrier Lyapunov function ( T t -BLF) is constructed. Then, with some mild assumptions, such as input-to-state stability (ISS) property of zero dynamics, upper boundedness of subsystems' nonlinear terms and some well-known small signal conditions, state feedback controllers (SFCs) constructed by adding a power integrator (AAPI) technique and the update law to estimate the unknown parameter are proposed to guarantee resultant closed-loop switched systems FT stable. The proposed method for switched systems is presented in a unified manner, capable of addressing FT stabilisation by effectively handling situations with or without output constraints. This is achieved through the construction of T t -BLF, which degenerates into a quadratic form when the output constraint disappears or approaches infinity. At last, the method is verified by a switched RLC circuit system (RLC-CS) and a numerical simulation.

Enhancing mathematical simulation: a novel integro spline quasi-interpolation for nonlocal dynamical systems

ABSTRACT In this research, we present a novel and computationally streamlined method to tackle nonlocal initial value problems through a combination of modeling and simulation. Our approach utilizes the Integro spline quasi-interpolation technique, renowned for its effectiveness in approximating nonlocal integrals. To validate the efficacy of our proposed method, we conduct comprehensive comparisons with alternative approaches found in the existing literature for integrating nonlocal functions. Additionally, we successfully apply our suggested approach to address nonlocal Riccati, resistor-inductor circuit, and Airy oscillator dynamical systems. The numerical results obtained from these applications convincingly demonstrate the advantages and effectiveness of our developed approach in enhancing mathematical simulation.

Latent Toehold-Mediated DNA Circuits Based on a Bulge-Loop Structure for Leakage Reduction and Its Application to Signal-Amplifying DNA Logic Gates.

DNA circuits based on successive toehold-mediated DNA displacement reactions, particularly entropy-driven DNA circuit (EDC) systems, have attracted considerable attention as powerful enzyme-free tools for dynamic DNA nanotechnology. However, background leakage (noise signal) often occurs when the circuit is executed nonspecifically, even in the absence of the appropriate catalyst DNA (input). This study designed and developed a new latent toehold-mediated DNA circuit (LDC) system that relies on a bulge-loop structure as a latent toehold toward leakage reduction. Furthermore, the number (size) of nucleotides (nt) in the bulge-loop is found to play a significant role in the performance (i.e., leakage, signal, and kinetics) of LDC systems. In fact, the signal rate for the LDC systems increased as the number of nt in the bulge-loop increased from 4 to 8, whereas the leakage rate of the LDC systems with bulge-loops of 7 nt or less was low, but the leakage rate of the LDC system with a bulge-loop of 8 nt increased significantly. Note that the LDC system with the optimal bulge-loop (7 nt) was capable of not only reducing the leakage but also accelerating the circuit speed without any signal loss, unlike methods of reducing the leakage by reducing the signal reported previously for the conventional EDC systems. These facts indicate that the 7 nt bulge-loop acts as a "latent" toehold for the DNA circuit system. By using the amplification function of output signals with an accelerated circuit and reduced leakage, our LDC system with a 7 nt bulge-loop could be applied directly and successfully to signal-amplifying DNA logic gates such as OR and AND gates, and thus, sufficient output signals could be obtained even with a small amount of input. These findings reveal that our LDC systems with a bulge-loop structure can replace the conventional EDC system and have enormous potential in the field of DNA nanotechnology.

Discharge and Thermal Distribution Characteristics of Electric Vehicle Battery Pack in Closed Circuit System

This paper presents an experimental study of the depth of discharge (DOD) and temperature distribution characteristics at different locations of the lithium-ion battery (LIB) pack in the closed circuit system. Three different discharge power setups i.e., 600 W, 800 W, and 1000 W are prepared for investigating the depth of discharge and temperature characteristics of commercial LIB. Voltage measurement was implemented to achieve the DOD curve, while thermocouple measurement was used to identify real-time temperature at four different locations of the LIB. As a result, internal resistance and discharging time tend to be increased, while the voltage and current decline linearly from 0% to 80% of LIB capacity. Discharge power greatly affected the four variables when the process continued to the 10% cut-off voltage. Furthermore, the heat generation of the LIB caused a rise in temperature on its surface. The highest temperature was identified on the LIB cell surface followed by an air gap, internal surface casing, and external surface casing temperature. Among all locations, the real-time temperature on the LIB surface operated close to the upper limit of optimum temperature. Due to that reason, increasing of discharge power should be maintained to extend battery cycle life as well as to prevent battery failure. The high-temperature difference between the LIB surface and air gap during the discharging process indicated that there is required heat transfer enhancement.

Chemical surface modification for the preparation of MgO cladding to enhance magnetic properties of Fe-Si-Nb-B-Cu nanocrystalline soft magnetic composites

This study employed chemical synthesis and decomposition techniques to fabricate MgO insulation coating on the surface of nanocrystalline soft magnetic powder. It was found that this coating effectively suppresses the time lag effect in the magnetization process of soft magnetic materials under high-frequency alternating magnetic fields, consequently reducing the overall losses of soft magnetic composite materials by mitigating the time-dependent effects during magnetization. Specifically, at an MgO content of 0.8 wt%, the power losses of nanocrystalline soft magnetic composite materials decreased from 519.13 kW/m3 and 3665.78 kW/m3 to 277.69 kW/m3 and 2718.3 kW/m3 respectively, under alternating magnetic fields with magnetic induction strengths of 20 mT and frequencies of 1 MHz and 3 MHz. The MgO insulation coating effectively mitigated the relaxation phenomenon in the dynamic hysteresis loops of nanocrystalline soft magnetic composite materials within dynamic magnetic fields, reducing the adverse effects of internal eddy currents in high-frequency alternating magnetic fields, thereby confirming the close relationship between magnetic hysteresis losses and eddy current losses in soft magnetic composite materials. Additionally, with the increase in MgO content, there was a significant improvement in the quality factor of nanocrystalline soft magnetic composite materials, showing a decreasing trend in the imaginary part of the complex permeability, which reflects the magnitude of power losses. Furthermore, the positive response of MgO coating in enhancing DC superimposition performance and reducing inductance impedance values has been validated, underscoring its crucial role in improving the stability of circuit systems.

A Dual Triggering Scheme to Adaptive Fuzzy Resilient Control of Switched Nonlinear Systems Against Mixed Attacks.

A dual event-triggered adaptive fuzzy resilient control scheme for a class of switched nonlinear systems with vanishing control gains under mixed attacks is proposed in this article. The scheme proposed achieves dual triggering in the channels of sensor-to-controller and controller-to-actuator by designing two new switching dynamic event-triggering mechanisms (ETMs). An adjustable positive lower bound of interevent times for each ETM is found to preclude Zeno behavior. Meanwhile, mixed attacks, that is, deception attacks on sampled state and controller data and dual random denial-of-service attacks on sampled switching signal data, are handled by constructing event-triggered adaptive fuzzy resilient controllers of subsystems. Compared with the existing works for switched systems with only single triggering, more complex asynchronous switching caused by dual triggering and mixed attacks and subsystem switching is addressed. Further, the obstacle caused by vanishing control gains at some points is eliminated by proposing an event-triggered state-dependent switching law and introducing vanishing control gains into a switching dynamic ETM. Finally, a mass-spring-damper system and a switched RLC circuit system are applied to verify the obtained result.

Anatomical correlates of apathy and impulsivity co-occurrence in early Parkinson’s disease

BackgroundAlthough apathy and impulse control disorders (ICDs) are considered to represent opposite extremes of a continuum of motivated behavior (i.e., hypo- and hyperdopaminergic behaviors), they may also co-occur in Parkinson’s disease (PD).ObjectivesWe aimed to explore the co-occurrence of ICDs and apathy and its neural correlates analyzing gray matter (GM) changes in early untreated PD patients. Moreover, we aimed to investigate the possible longitudinal relationship between ICDs and apathy and their putative impact on cognition during the first five years of PD.MethodsWe used the Parkinson’s Progression Markers Initiative (PPMI) database to identify the co-occurrence of apathy and ICDs in 423 early drug-naïve PD patients at baseline and at 5-year follow-up. Baseline MRI volumes and gray matter changes were analyzed between groups using voxel-based morphometry. Multi-level models assessed the longitudinal relationship (across five years) between apathy and ICDs and cognitive functioning.ResultsAt baseline, co-occurrence of apathy and ICDs was observed in 23 patients (5.4%). This finding was related to anatomical GM reduction along the cortical regions involved in the limbic circuit and cognitive control systems. Longitudinal analyses indicated that apathy and ICDs were related to each other as well as to the combined use of levodopa and dopamine agonists. Worse apathetic and ICDs states were associated with poorer executive functions.ConclusionsApathy and ICDs are joint non-exclusive neuropsychiatric disorders also in the early stages of PD and their co-occurrence was associated with GM decrease in several cortical regions of the limbic circuit and cognitive control systems.

Trigger circuit design and system integration for simultaneous measurement of human EEG, motion, and gaze

Trigger circuit design and system integration for simultaneous measurement of human EEG, motion, and gaze

Sound Quality Analysis and Optimization of Loudspeakers Based on Electromagnetic Principle

The sensory feeling brought by the speaker’s sound quality determines the speaker’s quality, and whether a better speaker can be designed depends on whether the factors affecting the speaker’s sound quality can be correctly analyzed. Through the analysis of the loudspeaker structure and the application of physics in the loudspeaker, the factors affecting the sound quality of the loudspeaker are analyzed from the two aspects of the magnetic circuit system and the vibration system, which is intended to help designers analyze and understand the physical characteristics of the loudspeaker, to make better audio equipment.

Experimental investigation of the external load effect on thermoelectric generator discharge time in a low power energy harvesting system

Thermoelectric generator systems are often evaluated and studied in open circuit and close circuit modes. In the open circuit case, minimum heat flux passes across the thermoelectric module and the module does not have any thermal losses. Moreover, in the close circuit system, the external consumer is connected to the module and higher heat is pumped from its hot side to cold side. Hence, investigating the effect of external load resistance as the consumer connected to the module on its response is a significant issue in thermoelectric systems. In this study, to evaluate the effect of various consumers (4, 8, 10, 15, 20 and 30 Ω) over the module on discharge time, output voltage and temperature on both sides of the module, thermoelectric systems lacking and containing phase change material as the useful means for energy storage and thermal management of thermoelectric system were designed and exposed to constant heat loads. Results of this study show that the power consumption of the internal resistance of the module (connected to the consumer) led to an increase in the temperature of both sides of the module compared to open circuit systems. Therefore, the thermal balance and temperature distribution over the module changes and more affected. The maximum output power and discharge time were obtained at the external resistance of 4 Ω (close to the average internal resistance of the module) in the studied systems. The phase change material prevented excessive temperature on the hot side during the charging process and provided proper thermal management to enhance voltage generation and discharge time. The thermoelectric generator is an effective technology in starting consumers with low resistance, such as light bulbs and remote controls.

Modeling of self-oscillating flexible circuits based on liquid crystal elastomers

Deformable and movable flexible circuits are characterized by simple construction, precise control, flexible and versatile morphology, and various functional forms, which can be used to build dynamic circuit systems, achieve the integration of drivers and controllers, and automated control of circuits, etc. Limited to conventional materials, challenges remain in designing novel self-oscillating flexible circuit. In this paper, a concept for a self-oscillating flexible circuit based on electrothermally responsive liquid crystal elastomers (LCEs) is presented, which is capable of generating periodic continuous oscillation under steady applied voltage. The governing equation of the self-oscillating LCE-based flexible circuit is formulated, and numerically calculated by fourth-order Runge-Kutta method with Matlab software. The numerical calculations reveal that the self-oscillating flexible circuit involves two motion patterns, i.e., static pattern and self-oscillation pattern. The self-oscillation arises from the coupling between the electrothermally driven deformation of the LCE film and its motion, and the electrothermal input compensates for the damping dissipation. Moreover, it is found that system parameters affect the self-oscillation of flexible circuit and that there are critical values of these parameters that trigger self-oscillation. Based on the self-oscillating flexible circuit, we conceptualized an automatic control device and a disturbance monitoring device, realizing automatic control of electrical appliances without human intervention and automatic monitoring of external disturbances. The proposed self-oscillating LCE-based flexible circuit features convenient operation, simple construction, flexibility, lightweight, and noiseless operation, rendering it suitable for constructing dynamic circuit systems, achieving actuator-controller integration, and facilitating circuit automation applications.

Secure memory adaptive event‐triggered filter design of nonlinear network system under hybrid network attacks with application to tunnel diode circuit

AbstractThis article investigates the problem of secure memory adaptive event‐triggered filter design for nonlinear network systems under hybrid network attacks. First, the introduction of memory adaptive event‐triggered mechanism and numerical quantization is employed to enhance system performance, optimize network channel utilization, and prevent network congestion. Second, we consider the impact of deceptive attacks and DoS attacks occurring in the network channel on data transmission, which form the hybrid network attacks studied in this article. Subsequently, based on the established error model, we derive sufficient conditions for the mean‐square exponential stability of the system under a given performance index using Lyapunov–Krasovskii function and linear matrix inequality (LMI) techniques. Furthermore, the filter parameters are determined using the LMI method. Finally, we illustrate the feasibility and generality of the conclusions through numerical simulation examples and a tunnel diode circuit system.

A strategy to improve the thermal fatigue resistance of solder joints based on amorphous Co-P coating to spontaneously build skeleton of CoSn3 laths

Integrated circuit systems are always suffering the temperature cycling environment caused by frequent power on and off. Mismatch in thermal expansion coefficients among chip package components will cause severe cyclic stress to the solder joints. During thermal fatigue, β-Sn grains tended to generate thermal fatigue cracks at the grain boundaries. This work proposed a strategy of using amorphous Co-15 at.% P coating as the interface layer to inhibit the initiation and propagation of thermal fatigue cracks and improve the shear strength of solder joints by numerous endogenous CoSn3 laths. Mechanistically, based on the amorphous structure of the Co-P coating, Co atoms would massively and rapidly diffuse into the molten solder during the liquid-solid diffusion stage of reflow soldering, and the eutectic solidification together with β-Sn spontaneously precipitated numerous laths of CoSn3 intermetallic compounds (IMC), which were evenly distributed and became the skeleton of the solders. The skeleton-like CoSn3 laths with high elastic modulus were the reinforcing phase of Sn-based solder, but also refined the grains of β-Sn. The refinement of β-Sn grains and the strengthening of CoSn3 laths played an important role in inhibiting the initiation and propagation of thermal fatigue cracks. In addition, a discontinuous Co-Sn IMC layer was formed between the amorphous Co-P and the solder. The alternating appearance of CoSn3 and relatively soft β-Sn at the interface avoided the generation of cracks at the interface during temperature cycling.

Design and implementation of a preset operational amplifier based on basic digital and analog hybrid circuit

In the vast landscape of electronic engineering, the indispensable roles of both analog and digital circuits are unequivocally recognized. Analog circuits, with their foundational principles, are extensively harnessed in areas encompassing audio, video, power systems, and particularly, amplifiers. Conversely, digital circuits, integral to modern-day technological advancements, are dominantly present in computing platforms, telecommunication systems, control mechanisms, and data storage infrastructures. Amplifiers, a cornerstone in analog circuit designs, principally focus on magnifying the amplitude of input signals, whether it be in terms of voltage or current. This amplification process hinges on the strategic configuration of electronic elements such as transistors, resistors, and capacitors. This paper endeavors to marry the attributes of digital and analog circuits. Through the adept utilization of fundamental electronic components, an innovative amplifier design capable of preset amplification ratios is birthed. The practicality and efficacy of this amplifier are rigorously validated via its hands-on assembly and experimental testing in a laboratory setting. Results consistently underscore the amplifiers adeptness in delivering precise signal amplification, conforming to its predetermined ratios. Such a design, rooted in its simplicity yet offering profound versatility, beckons further exploration. It stands as a beacon for potential future adaptions, tailored to suit a gamut of applications, and is poised to seamlessly dovetail into more sophisticated circuit systems.

Grid Strength Impedance Metric: An Alternative to SCR for Evaluating System Strength in Converter Dominated Systems

Short circuit ratio is an outdated measure of system strength in converter dominated systems as the useful behaviour of inverter-based resources is not represented. While still useful for determining fault current provision, converter connected generation contributes to short circuit level and system strength in a different way to traditional synchronous generation. Additionally, traditional measures only account for system strength at the fundamental frequency while converters possess complex interactions across a frequency range. A novel method of determining system strength across this frequency range from the network impedances is proposed in this paper. The approach known as the Grid Strength Impedance Metric, calculates the system strength independently from short circuit level. The unique contribution of grid-following and grid-forming converters is represented by including the multiple-input multiple-output converter output impedances in the calculation. Small-signal impedance models are employed, and the metric is largely concerned with short-term voltage stability, but some inferences can be made for longer timescales. The approach is validated using time domain simulations to check for any identified areas of weakness in the frequency range. The Grid Strength Impedance Metric successfully represents the useful behaviour of grid-forming converters, indicating an enhancement in voltage stiffness in locations of deployment.

Dynamic Event-Triggered H∞ Control for Networked Control Systems With Denial-of-Service Attacks

A dynamic event-triggered H∞ control for networked control systems (NCSs) subject to denial-of-service (DoS) attacks is investigated in this paper. Firstly, the DoS attacks model in communication channel are established based on stochastic variables that obey the Bernoulli distribution, and the attacks rate over network along with switching rules are described. Secondly, the dynamic event-triggered mechanism (DETM) is applied to weaken the influence of DoS attacks and avoid excessive transmission. The threshold parameters under the event-trigger condition can be adjusted by the dynamic characteristics of the systems. Thirdly, by using Lyapunov-Krasovskii functional (LKF) and Linear matrix inequality (LMI) methods, a sufficient condition for NCSs to satisfy the asymptotic stability of given H∞ is obtained. In addition, a cooperative design scheme of DETM parameters and controller gain is proposed. Finally, a RLC series circuit systems is used as an example to show the effectiveness of the method.

A system of feed-forward cerebellar circuits that extend and diversify sensory signaling.

Sensory signals are processed by the cerebellum to coordinate movements. Numerous cerebellar functions are thought to require the maintenance of a sensory representation that extends beyond the input signal. Granule cells receive sensory input, but they do not prolong the signal and are thus unlikely to maintain a sensory representation for much longer than the inputs themselves. Unipolar brush cells (UBCs) are excitatory interneurons that project to granule cells and transform sensory input into prolonged increases or decreases in firing, depending on their ON or OFF UBC subtype. Further extension and diversification of the input signal could be produced by UBCs that project to one another, but whether this circuitry exists is unclear. Here we test whether UBCs innervate one another and explore how these small networks of UBCs could transform spiking patterns. We characterized two transgenic mouse lines electrophysiologically and immunohistochemically to confirm that they label ON and OFF UBC subtypes and crossed them together, revealing that ON and OFF UBCs innervate one another. A Brainbow reporter was used to label UBCs of the same ON or OFF subtype with different fluorescent proteins, which showed that UBCs innervate their own subtypes as well. Computational models predict that these feed-forward networks of UBCs extend the length of bursts or pauses and introduce delays-transformations that may be necessary for cerebellar functions from modulation of eye movements to adaptive learning across time scales.