Input Switching Research Articles

Jc(B) transformer rectifier flux pump optimisation via simulation

Abstract Superconducting power supplies commonly known as flux pumps are becoming viable products in various industries. In this work we investigate magnetically switched ( J c ( B ) ) half-wave transformer rectifier flux pumps (TRFPs) via a simulation previously validated against an experimental system. Upgrades to the model are introduced, namely the transition to a fully hysteretic transformer reluctance model and the introduction of a conduction cooling thermal model. The conduction cooling model allows direct comparison between liquid cryogen and conduction cooled systems, highlighting the distinct variations in response. This study focuses on parameter sweeps over some of the most important aspects of a TRFP such as; input power, cooling paths and switch length. The findings from these variable sweeps shed light on how to best design the different aspects of a TRFP for most applications and the conclusions drawn throughout this work can be applied to most TRFP types. Some of the major findings from this work are; i. the need for dedicated cooling busses in TRFP switches, ii. that increased switch lengths increase voltage generation but negatively impact cooling effectiveness iii. that the reduction of the metallic coatings surrounding commercial coated conductors results in larger switch voltages.

Robust Control for Multiplayer Nonzero‐Sum Differential Games With Switching Topology and Input Delay

ABSTRACTThis article investigates a multiplayer nonzero‐sum differential game (MNDG) with switching topology and input delay. The Hamilton–Jacobi–Isaacs (HJI) equation is used to derive the optimal control strategies. To solve the issue of switching topology, the control strategies are decoupled with the communication topology. Then, the stability of the system can be achieved regardless of changes in communication topology with the designed control strategies. This does not require a restriction on the dwell time, making the system stability conditions more relaxed. The Lyapunov–Krasovskii functional (LKF) is constructed to prove the stability of the system in the presence of time‐varying input delay. To cope with the real‐world situation, the input delay is considered to be disturbed by a time‐varying perturbation in this article. With these treatments, the system is more in line with real‐world applications. Simulation examples are given to validate the efficiency of the presented methods.

Design and Evaluation of Controller-Based Raycasting Methods for Efficient Alphanumeric and Special Character Entry in Virtual Reality.

Alphanumeric and special characters are essential during text entry. Text entry in virtual reality (VR) is usually performed on a virtual Qwerty keyboard to minimize the need to learn new layouts. As such, entering capitals, symbols, and numbers in VR is often a direct migration from a physical/touchscreen Qwerty keyboard-that is, using the mode-switching keys to switch between different types of characters and symbols. However, there are inherent differences between a keyboard in VR and a physical/touchscreen keyboard, and as such, a direct adaptation of mode-switching via switch keys may not be suitable for VR. The high flexibility afforded by VR opens up more possibilities for entering alphanumeric and special characters using the Qwerty layout. In this work, we designed two controller-based raycasting text entry methods for alphanumeric and special characters input (Layer-ButtonSwitch and Key-ButtonSwitch) and compared them with two other methods (Standard Qwerty Keyboard and Layer-PointSwitch) that were derived from physical and soft Qwerty keyboards. We explored the performance and user preference of these four methods via two user studies (one short-term and one prolonged use), where participants were instructed to input text containing alphanumeric and special characters. Our results show that Layer-ButtonSwitch led to the highest statistically significant performance, followed by Key-ButtonSwitch and Standard Qwerty Keyboard, while Layer-PointSwitch had the slowest speed. With continuous practice, participants' performance using Key-ButtonSwitch reached that of Layer-ButtonSwitch. Further, the results show that the key-level layout used in Key-ButtonSwitch led users to parallel mode switching and character input operations because this layout showed all characters on one layer. We distill three recommendations from the results that can help guide the design of text entry techniques for alphanumeric and special characters in VR.

Studying the transient process of an intermittent control system from its response property

As we all know, the output of a system is affected by its input and response properties. When the input switches, there must exist a transient process in the output and this transient process is different for different systems due to their different response properties and different dynamic process. However, the response property and dynamic process have rarely been studied in the obtained achievements about the transient process of an intermittent control system. The obtained achievements cannot agree with the real physical process and cannot be applied to study the transient process in engineering.By introducing the unit step function and taking the intermittent input signal as a piecewise signal, we have studied the transient process. Our research shows that the transient process is related to the response characteristics, historical dynamic information, and control parameters, which agrees well with the real system and can be applied to analyze and optimize the transient process in engineering. Some examples in our paper verify our theoretical achievements.

Export contraction and input switching in an aging China

Whether an aging China is increasingly losing its low-cost export advantages? More importantly, which type of inputs' dynamics occurs to adapt to the above-mentioned circumstance? Using an instrumental-variable strategy, our empirical analysis finds that population aging leads to a contraction in China's export share since it causes a shortage of middle-aged workers and thereby higher labor cost. We also show that population aging leads to a substitution of labor with capital, but does not promote technology level in the context of China. Moreover, we document that the substitution of labor with capital occurs mainly in the firms with high productivity, large scale, high capital intensity, low credit constraint, high export intensity and private firms.

Unidirectional switch model for multiservice traffic with polymodal distribution

The modern stage of development of telecommunication networks is characterized by active improvement of routing algorithms in packet-switched networks taking into account the provision of the required quality of service. The need to transfer large amounts of information is due to the need to ensure the normal functioning of modern multimedia applications, in particular such as IP telephony, video and radio broadcasting, interactive distance learning, which determines the multiservice nature of traffic, which is heterogeneous, and its statistical properties in most cases are of a complex polymodal nature. Taking into account the fact that traditional Poisson models providing FIFO servicing of network traffic for solving modern telecommunication problems lead to overly optimistic results in terms of delays, there is a need to develop a new mathematical model of a unidirectional switch providing FIFO servicing of multiservice traffic with polymodal distribution taking into account the provision of the required quality of subscriber service and an algorithm for estimating its main parameters. Development of a mathematical model of a unidirectional switch FIFO-service of multiservice traffic with polymodal distribution taking into account the provision of the required quality of subscriber service and an algorithm for estimating its main parameters. A new mathematical model of a unidirectional switch implementing FIFO-service of multiservice traffic with polymodal distribution has been developed, allowing one to estimate the probabilities that packets arriving at the switch input will not be processed due to overflow of its buffer memory and exceeding the maximum packet processing time. The model takes into account the delays introduced by the channel and channel equipment during the distribution and processing of packets from the source to the switch in question. Recommendations for modeling traffic processing to ensure the specified accuracy of the results are presented.

WITHDRAWN: A 32-channels analog multiplexer with crosstalk compensation technique in 45nm CMOS

This paper presents a multiplexer that is capable of modulating 32-channels analog signal, which is a promising approach to simplify transmission system. An 8-channels prototype multiplexer with integral functionality and non-ideal factors is fabricated in 45 nm CMOS with area of 0.59 mm2, and verified in a QAM-256 system with 1.2V supply. The proposed multiplexer employs a semi-tree structure to achieve compromise between scale and speed. To relieve adverse effect caused by crosstalk between channels, the auxiliary reset compensation circuit combined with a dedicated timing sequence is utilized. Additionally, the proposed high-speed gate voltage bootstrap switch and high-bandwidth input buffer ensure that the signal remains linear during transmission. In the experimental result, the multiplexer can achieve a pulse width of at least 77ps in 8Gbps code rate, and the root mean square error due to nonlinearity between differential input and output is 1.869 %. The error vector magnitude (EVM) obtained by analyzing output versus input of multiplexer is less than 1.413 %.

Design of fuzzy logic controlled zero voltage switching based interleaved high gain converter

The conversion of low level DC voltage to high level DC voltage at lower duty ratios with less ripple current at source side is a challenging task in the distributed generation systems. Active switched inductor (ASL) converter is a high gain converter and has a large amount of input ripple current due to the parallel charging of the inductors during on time of the switches and series discharge of the inductors during off time of the switches. This large input ripple current in the converter when used in distributed generation (DG) affects the life time of low voltage batteries and fuel cells, the efficiency of photovoltaic source, increases the size and losses in the filtering stages and decreases the power density of the converters. In this paper, soft switching of interleaved active switched inductor (IASL) through Zero Voltage Switching (ZVS) is designed to overcome the limitations of ASL. The performance is analyzed in terms of its gain, input current ripple, switching loss and efficiency. An M-type resonant switch is used to achieve soft switching through ZVS technique.A proper value of resonant elements (inductor and Capacitor) is designed to achieve ZVS to improve the efficiency. Regulated voltage of proposed converter is required in DG systems and is possible with closed loop control. Fuzzy Logic controller (FLC) is designed to regulate the voltage and its dynamic performance is analyzed for different load values and also for sudden changes in load. Hardware model of the proposed ZVS based IASL converter with FLC is implemented and the results are verified with simulation results obtained from MATLAB Simulink.

Design of power supply system for portable aviation inspection equipment

Given that airborne electronic equipment may have a variety of wiring methods and may encounter a set of systems using multiple power supplies, it is necessary to take some measures on the circuit to ensure the normal work of the power supply and the post-circuit. A portable aviation detection equipment power supply system is designed in this paper. The system supports simultaneous access of two power supplies to identify and judge the input power supply and switch between the battery and the external power supply, effectively avoiding the security risks caused by battery backflow current. The battery power is monitored in real-time through the battery power detection circuit and will be reminded when the battery power is too low. Since the circuit uses a MOS tube to control the switching of the power supply, there is almost no voltage drop loss. In addition, the EMC protection circuit is set up at the power supply side to further improve the safety and reliability of the system.

Optimizing elastic optical networks quality of transmission with an empirical optical amplifier gain saturation model

In this paper, we revisit the problem of adjusting transceiver power, amplifier gain, and nodal gain in optical-bypass-enabled networks, taking into account an empirical model of erbium-doped fiber amplifier (EDFA) gain saturation. We assume that network demands have been routed via the shortest possible paths. A heuristic algorithm, which estimates the degradation of the signal-to-noise ratio (SNR) for each demand, is used to assign the modulation level and spectrum slots to the routed demands. Our optimization process aims to maximize the minimum SNR margins of demands, by adjusting EDFA small-signal gain, variable optical attenuator (VOA) attenuation, and transceiver power. Constraints and impairments imposed by the physical-layer include EDFA and VOA gain limits, transceiver power limits, receiver sensitivity, insertion loss of optical switch input ports, EDFA gain saturation, EDFA noise, and fiber non-linear interference. These are modeled using the Gaussian noise model. The proposed optimization problem is formulated as a geometric programming problem and then converted into an equivalent convex problem.Numerical results suggest that in the optimal solution of our optimization, all demands are served with typically low bit error rates (BER) (<10−4). We calculate the operational gains of the EDFA to set the spans to full compensation whenever possible. Pre-amplifiers and line amplifiers do not experience gain saturation due to relatively small input powers, while approximately 10% of boosters undergo more than a 1 dB gain reduction due to high input powers. We observe that overlooking the effect of EDFA gain saturation and physical-layer-imposed constraints such as nodal gain limits or transceiver power limits during network optimization leads to a considerable number of blocked demands due to SNR degradation or high BER (>10−3).

Finite-time sliding-mode tracking control of uncertain chaotic systems in the presence of an external disturbance and an input saturation

ABSTRACT The study presents a Finite-time Sliding-mode Tracking Control (FSTC) technique to achieve the trajectory tracking of an uncertain chaotic system. The feature of the proposed control strategy possesses a high level of robustness even when the uncertain chaotic system is in the presence of external disturbances and input saturation. First, a nonlinear sliding surface with a fractional-order term is constructed using tracking errors so that the finite-time convergence of tracking errors can be attained. The design of the nonlinear sliding surface, i.e. the selection of control parameters, can shape the system response. Since chattering will result from such control design, a boundary layer is adopted in the controller design to mitigate the high-frequency switching of control signal inputs. The overall system stability and finite-time convergence of the tracking error are verified using Lyapunov stability criteria and the relevant lemma. Finally, the proposed FSTC is applied to the Genesio chaotic system in the presence of uncertainty, external disturbance, and input saturation. The simulation results reveal that the proposed control scheme is indeed feasible and effective for chaotic systems control.

Local stabilization of networked linear systems with decentralized switching controllers

In this paper, we consider the decentralized control design problem for a particular case of networked switched affine systems. The considered network consists of interconnected (identical) linear systems with the controlled input switching among a finite set of values. We address a challenging case where the network can be only locally stabilized. Scalable Lyapunov based conditions are proposed for designing such decentralized controllers. The derived conditions (theoretical and linear matrix inequalities) do not depend on the number of subsystems. Ellipsoidal estimates of the domain of attraction are given.

Research on electrical automation devices under embedded real-time operating system design

Abstract As the scale of the electrical system becomes more and more large and the structure becomes more and more complex, the performance of the electrical automation device is therefore required to be higher. This paper studies the electrical system automation device, and from the perspective of universality, designs and establishes the hardware platform of the electrical system automation device composed of six plug-ins, such as human-machine interface, auxiliary switch input, AC input, communication, power supply, and central processor. On this basis, μC/OS-II is adopted as the embedded real-time operating system of this paper to develop and design the software of the electrical system automation device. Then, the principle of the protection device for embedded system electrical automation is analyzed, and a microcomputer line protection device based on the full-circle Fuchs algorithm is proposed. The empirical analysis of the embedded system electrical automation device shows that the maximum system task response time is 145 μs and the minimum is 10 μs, which are all no more than 1 ms. When testing including the single board state, the keyboard, the alphabetical mode, the basic function, and the single board line module sending and receiving, the pass rate of all the testing items is more than 99%, which verifies that this paper is based on the embedded real-time operating system of the feasibility and effectiveness of the electrical automation device.

Current Collapse Phenomena Investigation in Automotive-Grade Power GaN Transistors

This work analyzes the impact of working conditions on the current collapse (CC) phenomenon for an automotive GaN device. For this purpose, some sensing circuits have been compared to find the most suitable for the considered GaN family. Simulations of the testing schematic have been performed, a prototype board has been created, and some measurements have been taken. Finally, the work has investigated the effect on the CC of the input voltage, current level, switching frequency, and duty cycle. The key outcome is that the temperature increment mitigates the CC phenomenon, which implies that the on-state resistance worsening (dynamic/static ratio), which is due to the CC, reduces with increasing temperature. Therefore, the typical increment of the dynamic on-resistance (RDSON) with increasing temperature is ascribable to the increment of the static one with temperature, while it is not at all an exacerbation of the current collapse phenomenon.

Nitrogen-doped carbon nanotubes for self-powered memristive systems

Memristive devices are one of the promising candidates for creating neuromorphic systems due to the possibility of multilevel switching, low operating voltages and high scalability. However, as with any passive element, the memristor requires an external bias voltage to operate, which requires the inclusion of a power source in the circuit. In this regard, of great interest are works on the creation of self-powered memristive systems consisting of connecting in series a memristor and a nanogenerator that converts the energy of the external environment into electrical energy [1, 2]. Such a memristive system has a high potential for applications in aerospace and implantable electronics. At the moment, the first self-powered memristive and sensor systems based on metal oxides and piezoelectric nanogenerators (PENG) have already been developed [2]. The main problems in this area are to reduce the size of the nanogenerator and to match the output parameters of the nanogenerator and the input parameters of the memristor. In the framework of this work, these problems are being resolved by creating a self-powered memristive system based on nitrogen-doped carbon nanotubes (N-CNTs). Previously, we studied the memristive properties of N-CNTs and showed that nanotubes demonstrate reproducible multilevel switching with a resistance ratio in the high- and low-resistance states (HRS/LRS) of about 4⋅105 [3, 4]. It was found that the memristive effect in N-CNTs is due to the incorporation of nitrogen atoms into the nanotube structure and the formation of an internal piezoelectric field [4]. As part of further studies, it was found that an array of vertically aligned N-CNTs is a promising material for creating PENG: the generated output voltage is hundreds of mV and the current generated by single nanotube reaches hundreds of nA [5]. The results obtained allow us to speak about the possibility of developing a self-powered memristive system by connecting in series a memristor and PENG based on N-CNTs. To optimize the output characteristics of the PENG, in particular, the amplitude of the generated voltage, and the input switching voltage of the N-CNT-based memristor, studies were carried out to increase the piezoelectric response and reduce the switching voltage of the N-CNT resistance by changing the concentration of the dopant nitrogen in the nanotube growth process. It was found that it is necessary to grow N-CNTs with a doping nitrogen concentration of up to 12% and a high aspect ratio of length to diameter (more than 60) to create PENG with an output voltage of up to 2 V. These N-CNT parameters are provided at a low growth temperature (500–550 C°) and high ratio of acetylene and ammonia flows (1:5 - 1:6). On the contrary, the N-CNTs with a small aspect ratio (less than 30) and doping nitrogen concentrations of 4–6% are required for the manufacture of memristors with a minimum switching voltage (about 2 V), These N-CNT parameters are provided by increasing the growth temperature to 615 C° and reduction in growth time. The obtained results can be used in the development of self-powered memristive and sensor systems based on nitrogen-doped carbon nanotubes.

How firms accumulate inputs: Evidence from import switching

We uncover new dynamic facts in Colombian manufacturing importers’ data. First, imported input switching, a firm’s simultaneous adding and dropping of foreign intermediates, is pervasive and a substantial fraction of firm’s imports. Second, larger firms switch more conditional on age, whereas younger firms switch more conditional on size. Third, the number of imported varieties increases with firm age. Fourth, inputs of lower expenditure are more frequently dropped. Fifth, firms that switch more, have larger sales growth. Analogous facts also hold for suppliers. We propose a dynamic model where firms accumulate foreign suppliers and choose which heterogeneously productive intermediates to import. A firm compares each input’s productivity across suppliers and keeps the best source, switching, lowering its unit cost, and growing in size. In the calibrated model, a 20% tariff reduction: (1) generates a 5.2% increase in welfare across steady states, and (2) upon impact only 76% of the gains accrue.

Experimental and numerical investigation of the novel downhole intensifier controlled by electromagnetic valve

Stress release with rock slotting by ultra-high-pressure water jet is an effective method in reducing rock strength in the bottom hole caused by high in-situ stress in deep formation. The characteristics of duration and frequency of the water jet are vital for forming different grooves to release downhole stress. To improve the duration of the high-pressure water jet and modulate different jet frequency, a kind of downhole intensifier controlled by electromagnetic valve was developed and proposed. The water jet performance and the motion characteristics of the plunger of the intensifier were studied in various input pressure and switch frequency of the electromagnetic valve based on experiments, and a series of numerical simulations were conducted considering the input pressure, stroke, and area ratio of the plunger. The results indicate that the output waveform of the intensifier goes like a square shape. Increasing the input pressure and the area ratio of the plunger can enhance the output pressure while the duration of the peak pressure decreased. The stroke of the plunger shows a significant effect on the duration of the peak pressure and jet frequency. Adjusting the switching frequency of the electromagnetic valve can easily change the duration of peak pressure, which is beneficial for forming grooves with different characteristics. The research is believed to provide an important reference in drilling Engineering for deep and ultra-deep wells.

Perforated auxetic honeycomb booster with reentrant chirality: A new design for high-efficiency piezoelectric energy harvesting

The present study develops an auxetic meta-structure booster to advance piezoelectric energy harvesting (PEH). The model comprised a three-dimensional (3D) cantilever beam equipped with an auxetic substrate bonded to a piezoelectric (PZT) point defect using an epoxy layer. The substrate used in this proposed energy harvester possesses an auxetic region responsible for generating auxetic behavior and concentrating stress in the PZT layer. The auxetic model called auxetic structure (AS)-II is inspired by ancient motifs and is designed based on the combination of several promising mechanisms, including reentrant, chiral, perforation, and honeycomb supercell. The finite element method is employed to create numerical models whose accuracy is confirmed by mesh convergence and available experimental data. A parametric study is conducted on the AS-II harvester to examine the influence of geometry and PZT material type on the harvested electrical power. Our research efforts stem from both mechanical and electrical circuit fields to fulfill the broadband design target within the desired ultra-low-frequency range of regardless of the resonance condition. As a result, the impact of other factors, such as load resistance, frequency, load amplitude, and bonding stiffness, on the PEH performance is further investigated. The reason behind such outstanding performance of AS-II is explained in terms of geometrical physics and stress distribution. The effect of geometrical dimensions on the auxetic behavior is also analyzed using Poisson’s ratio (PR) study. Subsequently, we demonstrate that this innovative adapter can advance the system’s performance in terms of harvested power and lightweight by a magnification factor of and times that of a plain substrate and and 3.16 times that of a conventional auxetic harvester, respectively. The present harvester is strain controllable, where it can set PR between and resulting in robust PEH even if switching input vibration from high to low levels. This new idea enables us to serve cantilever-type resonators at frequencies far lower than their resonant frequencies with small portions of incident excitement.

A Nonlinear Load Current Feedforward Strategy for the Charge-Controlled LLC Converter and Its Digital Implementation to Improve the Dynamic Response

Compared with the traditional single voltage loop control strategy in LLC converters, the charge-controlled LLC converter can significantly improve its dynamic response due to its model having the first-order feature. Generally, a load current feedforward method could improve the converter's dynamic response. However, for the LLC converter, it is almost impractical due to the unclear relationship between the load current and the control variable. To build this relationship, a mathematical expression between the load current change and the control variable is derived that can precisely offset the load disturbance and achieve faster dynamic response. The derived relationship is nonlinear, related to both input and output voltages and switching frequency, and is suitable for digital implementation. To further analyze the dynamic response, the output impedances with and without the load current feedforward control are established and analyzed, which visually demonstrates the dynamic improvement in the time domain through the calculation of the output impedance and load change spectrum in the frequency domain. Finally, a 120W LLC prototype with nominal 48V input and 12V output is built to verify the nonlinear load current feedforward control and its analysis.

Estimation of Common Mode noise and Differential Mode noise generated by DC-DC Power Converters

The study contains a review of the body of knowledge regarding differential mode (DM) and common mode (CM)noise and how they affect power converter performance. With an emphasis on practical application, this work seeks to give an estimation of differential mode (DM) and common mode (CM) noise for cutting-edge DC-DC power converters such as Zeta converters, Single Ended Primary Inductance Converters (SEPIC), and Cuk converters. Active noise separators and Differential mode noise separators are used as a measurement technique to quantify DM and CM noise, considering a number of variables including input voltage, output voltage, load current, and switching frequency. By using filtering techniques, DM and CM noise can be reduced. Both CM noise and DM noise are created by the Zeta converter at 114 dBµV and 108 dBµV, respectively. CM noise from the SEPIC converter is 119 dBµV, and DM noise is 114 dBµV. With values of CM noise 98 dBµV and DM noise 106 dBµV, Cuk converter produces less noise when compared to Zeta and SEPIC converter. The results show that power converters can generate DM and CM noise, and that this noise is over the Comité International Special des Perturbations Radioélectriques [CISPR] limit line. The conducted emission range for various electronic devices is provided by this standard. This study provides useful insights for power converter designers and engineers to optimize the performance of their systems in practical applications.