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Cascaded inverters are widely applied in applications where elevated ac voltages are required while using semiconductor devices with lower voltage ratings. Here, we focus on structures that require localized power transfer between low-voltage sources/loads dispersed across inverter dc links and the inverter ac-sides are series-connected across a three-phase medium-voltage ac grid. To date, decentralized controllers that allow for bi-directional power transfer in such systems are limited. To fill this gap, we propose a virtual oscillator controller which modulates the power processed by each inverter in a purely decentralized manner. The proposed controller uses only locally measured current, provides communication-free synchronization of the inverter modules, and enables control of power transfer in both directions. Moreover, it is implemented purely in time domain as opposed to phasor-domain based droop controllers. Stability is analyzed and a design procedure for the oscillator parameters is provided alongside relevant simulation and experimental results for a system of five series-connected inverters.

Photovoltaic (PV) inverters typically have a multiloop control architecture to facilitate extraction of maximum possible dc-side power and its transfer to an ac-side grid interconnection. In this paper, we integrate dc-side controls that modulate the dc-link voltage for peak PV power harvest with an ac-side dispatchable virtual oscillator controller (dVOC) that synchronizes to the grid. In particular, maximum power point tracking is realized via integral control which then generates a dc-link voltage command. From there, dc-side voltage regulation is achieved by modulating the power reference sent to the ac-side dVOC. The dVOC yields an ac voltage command which is tracked with nested voltage- and current-control loops in the synchronous reference frame. Ac-side functions are topped off with an ac-side current limiter to ensure proper operation during large grid transients. We then analyze the eigenvalues of this interconnected system and its participation factors to demonstrate timescale separation of the various control loops. The proposed framework is substantiated via simulations and experiments.

A decentralized control technique for minimizing the input and output current ripple in parallel connected dc-dc converters under both uniform and non-uniform operating conditions is presented in this paper. We solve two key problems related to obtaining minimum ripple operation of these converters. First, we eliminate the need for a centralized controller that manages system-wide pulse width modulation. This yields a decentralized structure where converters autonomously converge to the operating point with minimized ripple using only local voltage feedback. Second, we obtain a controller that can function in the presence of parametric mismatches as well as nonuniformities in converter duty ratios that naturally arise with heterogeneous input sources. More precisely, the proposed controller minimizes the fundamental switching harmonic under both uniform and asymmetric operating conditions. For the case studies we consider, a more than $4 \times$ reduction in net current ripple is observed compared to conventional methods. Moreover, the undesired fundamental harmonic is reduced by more than 30dB. Relevant analysis, simulation results and experimental results with 5 parallel-connected dc-dc converters validate the proposed method.

An interpatient classification method using the second lead for the Association for the Advancement of Medical Instrumentation (AAMI) standard is introduced. This study includes three parts. In the first part, the fuzzy matching algorithm is used to locate the key waveform points of Electrocardiogram (ECG) data. In the second part, the feature engineering algorithm is used to filter the extracted data sets. In the third part, the random forest model is carried out to realize the five classifications of heart disease by the selected features. The final precision, recall, and F1-score are 91%, 89%, and 90%, respectively.

With the development and wide application of new energy, the transaction information is huge. In this paper, a delegated power authority mechanism (DPPGC) is designed to achieve local block consensus, to ensure transaction security and the stability of the blockchain network. Through experimental simulation, it can be seen that the proposed DPPGC consensus mechanism can improve the security of the consensus and make the proportion of malicious nodes in the consensus node less than 20%.

This paper demonstrates how equivalent-circuit representations of grid-following power-electronic inverters can be realized within a SPICE-based development environment using common circuit components and VerilogA code. This facilitates computationally lean simulations of inverter networks leveraging the strengths of SPICE in large-scale simulations. We validate the approach with time-domain simulations for a modified version of the IEEE standard 118-bus system modeled in Virtuoso (a SPICE-based solver). Simulation results are compared—focusing on accuracy and computation speed—with results from a commonly used power-electronics simulation package. We note a significant decrease in simulation time with comparable signal resolution when simulating the network in SPICE.

With the development of Internet of things and mobile computing, users can access to the network in different places and in different scenarios. In order to make Internet of things users have better service experience, this paper proposes a distributed service migration mode (DSMM) for dynamic management of Internet of things resources. DSMM can dynamically migrate services in the whole network according to the user's access location and access scenario, so as to make the user’s service experience better. DSMM uses computing power, storage space, network bandwidth and data to define user services, and uses distributed hash table DHT to realize service migration without center, which can be used in large networks. DSMM proposed in this paper enhances the adaptability of Internet of things to provide services to users, and is an efficient dynamic resource management model for Internet of things.

In order to solve the problem of slow speed and low efficiency of product defect detection, this paper proposes an improved Fully Convolutional One-Stage Object Detection (FCOS) algorithm for detection, and compares it with several currently widely used target detection algorithms. Through experimental verification, the improved Fully Convolutional One-Stage Object Detection (FCOS) has improved the detection effect by 6.9% compared with the original Fully Convolutional One-Stage Object Detection (FCOS) algorithm, and the applicability of the improved Fully Convolutional One-Stage Object Detection algorithm is verified through experiments.

Virtual oscillator control (VOC) is a time-domain strategy for regulating the operation of grid-forming (GFM) inverters. The premise of this method is to leverage the dynamics of nonlinear oscillator circuits to realize controllers; the time-domain nature of the resulting implementation is starkly different from classical droop control methods. This paper considers VOC realized with the dynamics of the Andronov-Hopf oscillator, a second-order nonlinear dynamical system that enables GFM inverters to be dispatched and generate low-harmonic outputs while not compromising dynamic performance. Leveraging an equilibrium analysis of the involved dynamics and small-signal models, we put forth a side-by-side comparison of dynamic performance and small-signal stability with classical droop control. The results demonstrate superior dynamic performance of VOC, and broadly, the paper furthers efforts focused on modeling and analysis of this general class of GFM controllers.

Voltage controlled inverters in ac systems are susceptible to damage if the controller is not properly initialized before startup. Since currents are not controlled explicitly, the voltage reference of the controller must be closely aligned with the point of common coupling voltage to prevent large current transients when power delivery begins. In this paper, we are focused on a particular control strategy called virtual oscillator control and propose a pre-synchronization method that guarantees graceful addition of units into an existing ac system. The proposed method is generalized and can be used to add oscillator-controlled inverters to a stiff grid or an islanded microgrid with other inverters. An equivalent circuit model of the pre-synchronization control is derived along with its dynamical properties, design guidelines are given, and experimental results are shown for a 1.5kW inverter.

In order to evaluate the perceptual quality of images, a full-reference quality index, which is called principal component deviation (PCD), is presented. This research is motivated by the discovery that the filters learned by the probabilistic principal component analysis are closely resemble the neurons of the human visual system. These filters are used as a model of the visual system, which are trained on 100,000 color image patches of size 4×4 by probabilistic principal component analysis. The PCD relates the image quality with the deviation between two sets of features that extracted by the learned filters. Experimental results show that PCD has relatively low computational complexity and high correlation with subjective quality evaluations.

This study proposes a personal healthcare system to monitor, identify ectopic heartbeats, and provide services to patients with heart diseases. The proposed system includes three subsystems: (1) an electrocardiography (ECG) signal acquisition device to acquire ECG signals accurately; (2) an Android-based smartphone to display the actual ECG waveform and upload the signal to the Web platform for analysis of cardiac disorder events; and (3) a Web platform for feature selection and arrhythmia classification with the support vector machine algorithm. The classification algorithm can identify three types of heartbeats, namely, normal, atrial premature beat, and premature ventricular contraction. The average sensitivity, specificity, and accuracy of the classification algorithm over the training set are 98.5%, 96.7%, and 97.7%, respectively.

Power efficiency and stability are critical for wearable ECG application. The paper presents a Pulse-Width-Modulation (PWM) voltage type DC-DC converter, which has a small area of 0.32 mm2 on active chip, output voltage range of 0.8V to 3.5V, output power up to 7.5 mW, and peak efficiency of 95.8%. The simulation results show that the output voltage of the system is 1.8V, the output current is 4mA, the ripple voltage is 13mV and the efficiency is 86.1%, which meets the requirements of a presented system. The circuit will be fabricated by the SMIC in the near future with $0.18\ \mu\mathrm{m}$ Bipolar-CMOS-DMOS (BCD) process.

Recently, the demonstration of the ferroelectricity of $\alpha$ phase In 2 Se 3 $(\alpha -$In 2 Se 3 ) has opened new opportunities to develop two-dimensional small bandgap ferroelectric memories. Conventional ferroelectric hetero-junction memories have been widely studied but the performance is still limited by the large bandgap of oxide-based ferroelectric materials and limits the diode ON current and results in low ON/OFF ratio. Accordingly, we propose a novel resistive switching memory device based on the unique ferroelectric and semiconductor properties of $\alpha -$In 2 Se 3 . By forming the hetero-junction of $\alpha -$In 2 Se 3 with the highly degenerated $\mathrm{p}^{+} -$Si substrate, we achieve a giant ferroelectric resistive ON/OFF ratio of $2.3 \times 10^{6}$.

Advancements in digitalisation and cyber-physical automation are opening up new frontiers in the marine industry such as autonomous shipping and smart manufacturing of ships. However, the progress in automating the ship design process which is still very human dependent, is slow. This paper introduces an automated ship design and optimisation concept by Hybridising Evolutionary Algorithm and Morphing (HEAM) to enable a more intelligent and efficient ship design process. It maps the entire ship hull form into a genotype using Non-dominated Sorting Genetic Algorithm II (NSGA-II) and flexible modification through morphing to create efficient designs for the hull form. This new method achieves predictive designs with a performance improvement of 11.67%, while achieving increased efficiency and minimum user dependency.

Biometrics has recently been the go-to authentication method in most electronic devices due to its convenience. There are two types of biometrics – static biometrics and dynamic biometrics. Hand gesture can both static and dynamic biometrics. Static hand gesture can be in the form of static hand sign; whereas dynamic hand gesture can be in the form of moving finger, hand, or arm. And due to its continuity, dynamic biometrics is usually correlated with behavioral. Hand gesture can also be a combination of both static and dynamic biometrics, for example continuous hand signs, where the hand sign is the static and the changes from one sign to another is the dynamic. In our research, we will be using the combination of both static and dynamic hand gesture. In order to simulate the worst case scenario, all the participants were asked to perform the same static hand gesture. From the result, it has been shown that the system can discern individuals through their gesture behavior. The accuracy rate from the confusion matrix and equal error rate from receiver operating characteristic (ROC) are above 0.84 and below 0.0701 respectively.

The segment assembly machine is a very important part of the shield machine, which is to lining the excavated surface. The segment assembly machine must meet the following two conditions: the segment assembly machine must be lined a full circle of segments accurately and have six degrees of freedom to operate. And the piece assembly must reach high precision, requiring high assembly precision of each component, high rigidity and no creeping when running at low speed. In this research, the force model of the walking beam and roller set of the segment assembly device of shield machine are calculated and analyzed in detail by computer modeling technology and computer simulation technology. The three-dimensional computer-optimized model of the mechanical structure is obtained by a numerical method of the general continuous field problem and the approximate solution of the finite element method. The stress field distribution is obtained, while the stress field distribution map of the roller axle is obtained by the finite element force analysis software combined with the limit conditions in the actual working conditions. It also provides a more advanced design for optimized design of the mechanical structure of the walking beam and roller set and provides a reliable design method for the mechanical module of the segment assembly machine with that theoretical basis of strength design, stiffness design and stability design.

The segment assembly machine, an important part of the shield machine, must be ensured for the timely lining of the excavated tunnel to secure the normal operation and to continue to travel and excavate of the shield machine. The quality of the tunnel assembly will directly affect the penetration and surface settlement of the groundwater, and the speed of the assembly will directly determine that of the shield machine. Therefore, the high quality, speed, accuracy of assembly is the key to the development of shield machine technology. The segment assembly machine is used to lining the surface of the tunnel to ensure the excavated tunnel surface to be consolidated and to be excavated forward. This paper analyzes the function in detail firstly to check out working principle and overall composition of segment assembly translation system of the shield machine. A detail layout and structural optimization design analysis were carried out combined with the partial design and hydraulic control system. Through the coordination study of the mechanical mechanism and the hydraulic control system, the overall performance of the segment assembly translation system is comprehensively reviewed and the segment assembly translation system can be further developed.

The segment assembly system of shield machine is a multi-degree-of-freedom system by hybrid control using electricity and hydraulics. Its control method has great influence on the stability of the whole machine, the stability of the surface and the work efficiency of its system. In order to reduce surface settlement, the assembly machine must be efficient, stable and reliable in its work. The assembly system has six degrees of freedom, and control system of degree of freedom relies on a hydraulic system. Whether it is a translational circuit, a circumferential circuit, a radial circuit, a fine-tuning circuit, a locking circuit and so forth, each circuit achieves a corresponding function by controlling an actuator in the hydraulic system. The system is a hydraulic working system, which uses PLC to control hydraulic cylinders to realize the handling of material segments. The multi-degree of freedom system can realize various movement postures of the segments and position and lock the segments. This paper analyzed the mechanism of its multi-degree-of-freedom series-parallel system. The influencing factors of the weak link of the parallel multi-degree-of-freedom system are analyzed and modified. The research of the fine-tuning system was also carried out, and the control precision and stability of the system were improved through analyzing the influencing factors and optimizing the design of the fine-tuning system. It provides reasonable optimization methods and solutions for the hydraulic system design of various shield machines through the transformation and redesign of the hydraulic system.

The shield machine is a large-scale construction machine with intelligent and highly complex system to achieve the goal of excavation by a hybrid control system of machine with electricity and liquid. Due to the complex and varied working conditions of the excavation, it is necessary to consider the specific excavation parameters and use a variety of tool combinations in order to improve efficiency. Under this condition, this paper comprehensively considers the effects of various condition parameters on the tool. The working mechanism of the shield machine tool is studied by the computer technology. The influence of the environmental change of the working condition on the working mechanism of the tool is discussed in depth. The influence factors of service life of various materials are analyzed, which provides a theoretical basis for the selection of cutters. It provides a comprehensive evaluation mathematical model for the rational construction and application of the cutters, and an important theoretical basis on the development and construction of the intelligent engineering machinery