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A model-agnostic data enhancement (MADE) algorithm is proposed to comprehensively investigate the circular dichroism (CD) properties in the higher-order diffracted patterns of two-dimensional (2D) chiral metamaterials possessing different parameters. A remarkable feature of MADE algorithm is that it leverages substantially less data from a target problem and some training data from another already solved topic to generate a domain adaptation dataset, which is then used for model training at no expense of abundant computational resources. Specifically, nine differently shaped 2D chiral metamaterials with different unit period and one special sample containing multiple chiral parameters are both studied utilizing the MADE algorithm where three machine learning models (i.e, artificial neural network, random forest regression, support vector regression) are applied. The conventional rigorous coupled wave analysis approach is adopted to capture CD responses of these metamaterials and then assist the training of MADE, while the additional training data are obtained from our previous work. Significant evaluations regarding optical chirality in 2D metamaterials possessing various shape, unit period, width, bridge length, and separation length are performed in a fast, accurate, and data-friendly manner. The MADE framework introduced in this work is extremely important for the large-scale, efficient design of 2D diffractive metamaterials and more advanced photonic devices.

In the development and implementation of critical devices and systems, various methods are used to provide blocks, nodes, subsystems, and systems with the properties of controllability, self-testing, fault tolerance, and safe operation in case of failures. The synthesis of self-checking and fault-tolerant computing devices is carried out using the methods of information theory and coding. In this paper the features of error detection by a weight-based sum code, in which the weights are assigned to pairs of successive bits of the data vector with intersection, are considered. The weight coefficients are taken from an increasing power series of the number 2. Then a series of special permutations of the weight coefficients are carried out according to the described principles. Such codes are called weight-based sum codes with a series of permutations and are denoted as P m -codes ( m is the length of the data vector). The previously unknown properties of P m -codes that should be taken into account when developing and synthesizing testable, self-checking, and fault-tolerant computing devices and systems are established. The characteristics of detection of unidirectional, symmetrical, and asymmetrical errors by types and their multiplicities arising from the distortions of bits, as well as data and control vectors, are determined. It is shown that, despite the property of detecting any double errors in the data vectors for small lengths of the data vectors of m  < 10, the P m -codes cannot identify all the double errors that occur when one data bit and one control bit are distorted. The results of the experiments on error detection by the P m -codes at the outputs of the test combinational circuits are given. It is advisable to consider the established characteristics of the error detection by the P m -codes in the problems of the synthesis of reliable and safe automation and computation devices.

This study proposes a new demand-side management (DSM) technique, which is characterised by low computational requirements. The proposed technique relies on developing an operational matrix by the device local controller based on the device characteristics and the customer preferences. This matrix is sent to the energy management system (EMS) without the need to send any further information about the device or the customer preferences; then, the EMS chooses the optimal schedule for the device. To demonstrate the effectiveness of the proposed DSM technique, it is incorporated in an EMS that consists of three units controlled by a centralised microgrid controller (MGC). The three units managed by the MGC are the data collection and storage engine, the forecasting engine, and the optimisation engine. The EMS utilises the rolling horizon concept to manage real-time information and to provide the plug-and-play option for all controllable devices. Simulation results on a typical microgrid system show that the proposed DSM technique outperforms conventional DSM approaches in terms of the computational time.

The enhancement of distribution system operation is proposed in this paper by optimally controlling the installed switchable devices. The objective of the control is to simultaneously minimize system losses and improve system voltage profile. This objective may be achieved by optimally dispatching the controllable components (shunt capacitor and Load Tap Changer/LTC) taking into account system unbalanced. A Genetic Algorithm (GA) is developed to determine the load curve partition useful for effective LTC scheduling and switching constraint satisfaction. GA is also assigned to determine the hourly status of shunt capacitor switching and LTC tap position. For power flow analyses under unbalanced conditions, Forward/Backward Propagation Algorithm is developed and employed. The strategy is implemented on the IEEE 34-bus unbalanced distribution system and the resulted improvement is analyzed. The main contribution is inclusion of unbalanced system conditions into optimization problem.

The simplified circuit and modulation scheme is presented for a five-phase three-level voltage source inverter (FPTL-VSI). The simplified FPTL-VSI is a concatenation of a dual-buck stage and a two-level VSI (TL-VSI), and the space vector pulse width modulation (SVPWM) is used as the modulation scheme. Owing to the merit of the dual-buck stage which uses only four controllable switching devices, the TL-VSI can produce a three-level voltage waveform. By simplification of the space voltage vectors, a simplified SVPWM scheme can be obtained. Thus, the simplified FPTL-VSI reduces the hardware costs and improves the quality of the output voltage waveforms. Furthermore, the hardware implementation of the simplified SVPWM scheme can be easily realised. The experimental results prove the feasibility and validity of the proposed inverter and the modulation scheme.

We study how to manipulate by the δ -doping a giant magnetoresistance (GMR) device, which can be realized experimentally by depositing two parallel ferromagnetic stripes on top and bottom of the semiconductor GaAs/Al x Ga 1 - x As heterostructure. We demonstrate an obvious GMR effect in the device with a δ -doping. We also reveal that the magnetoresistance ratio depends not only on the weight but also on the position of the δ -doping. These interesting results will be helpful for designing controllable GMR devices.

The 20,000-ton combined train running has greatly promoted China’s heavy-haul railway transportation capability. The application of controllable train-tail devices could improve the braking wave of the train and braking synchronism, and alleviate longitudinal impulse. However, the characteristics of the controllable train-tail device such as exhaust area, exhaust duration and exhaust action time are not uniform in practice, and their effects on the longitudinal impulse of the train are not apparent, which is worth studying. In this work, according to the formation of the Datong–Qinhuangdao Railway, the train air brake and longitudinal dynamics simulation system (TABLDSS) is applied to establish a 20,000-ton combined train model with the controllable train-tail device, and the braking characteristics and the longitudinal impulse of the train are calculated synchronously with changing the air exhaust time, exhaust area, and action lag time under initial braking. The results show that the maximum coupler force of the combined train will decrease with the extension of the continuous exhaust time, while the total exhaust time of the controllable train-tail device remains unchanged; the maximum coupler force of the combined train reduces by 32.5% with the exhaust area increasing from 70% to 140%; when the lag time between the controllable train-tail device and the master locomotive is more than 1.5 s, the maximum coupler force of the train increases along with the time difference enlargement.

In the medical field and in soft robotics, flexible devices are required for safe human interaction, while rigid structures are required to withstand the force application and accuracy in motion. This paper aims at presenting controllable stiffness mechanisms described in the literature for applications with or without shape-locking performances. A classification of the solutions based on their working principle is proposed. The intrinsic properties of these adaptive structures can be modified to change their mechanical characteristics from a geometrical point of view or equivalent elastic properties (with internal mechanisms or with a change in material properties). These solutions are compared quantitatively, based on selected criteria linked to the medical field as the stiffness range, the activation time and the working conditions. Depending on the application and its requirements, the most suitable solution can be selected following the quantitative comparisons. Several applications of these tunable stiffness structures are proposed and illustrated by examples of the literature.

Flexible ultrasonic devices represent a feasible technology for providing timely signal detection and even a non-invasive disease treatment for the human brain. However, the deformation of the devices is always accompanied by a change in the acoustic field, making it hard for accurate focusing. Herein, we report a stable and flexible transducer. This device can generate a high-intensity acoustic signal with a controllable acoustic field even when the device is bent. The key is to use a low-impedance piezoelectric material and an island-bridge device structure, as well as to design a unique time-reversal algorithm to correct the deviation of signals after transcranial propagation. To provide an in-depth study of the acoustic field of flexible devices, we also analyze the effects of mechanical deformation and structural parameters on the corresponding acoustic response.

Two-dimensional (2D) vertically stacked heterostructures based on layered transition-metal dichalcogenides (TMDCs) have remarkable potential in future applications due to their rich interlayer related properties, such as interlayer excitons, tunable interlayer band alignments. However, the controlled growth of TMDC bilayer heterostructures with preferred stacking structure remains challenging. Here, we report a two-step van der Waals epitaxial vapor growth of WSe 2 /WS 2 vertically stacked bilayer heterostructures with controllable commensurate crystallographic alignments (so called AA and AB stacking), by controlling the deposition temperature. Moiré patterns were obtained in both AA and AB stacked WSe 2 /WS 2 heterostructures. The stacking configuration of the vertical heterostructures was verified by the second harmonic generation signals. Photoluminescence and Raman spectroscopy studies further confirm that the heterostructures with different stacking configuration have obviously different optical properties, which is ascribed to the distinct interlayer coupling and resonance excitation between the distinguishing AA and AB stacked heterostructures. The controlled growth of AA and AB stacked heterostructures could provide an importance platform not only for fundamental researches but also for functional electronic and optoelectronic device applications.