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This work focuses on the use of reconfigurable intelligent surface (RIS) in dual-function radar-communication (DFRC) systems to improve communication capacity and sensing precision, and enhance coverage for both functions. In contrast to most of the existing RIS aided DFRC works where the RIS is modeled as a diagonal phase shift matrix and can only reflect signals to half space, we propose a novel beyond diagonal RIS (BD-RIS) aided DFRC system. Specifically, the proposed BD-RIS supports the hybrid reflecting and transmitting mode, and is compatible with flexible single/group/fully-connected architectures, enabling the system to realize full-space coverage. To achieve the expected benefits, we jointly optimize the transmit waveform, the BD-RIS coefficients, and sensing receive filters, by maximizing the minimum signal-to-clutter-plus-noise ratio for fair target detection, subject to the constraints of the communication quality of service, different BD-RIS architectures and power budget. To solve the non-convex and non-smooth max-min problem, a general solution based on the alternating direction method of multipliers is provided for all considered BD-RIS architectures. Numerical simulations validate the efficacy of the proposed algorithm and show the superiority of the BD-RIS aided DFRC system in terms of both communication and sensing compared to conventional RIS aided DFRC.

As a promising technology in beyond-5G (B5G) and 6G, dual-function radar-communication (DFRC) aims to ensure both radar sensing and communication on a single integrated platform with unified signaling schemes. To achieve accurate sensing and reliable communication, large-scale arrays are anticipated to be implemented in such systems, which brings out the prominent issues on hardware cost and power consumption. To address these issues, hybrid beamforming (HBF), beyond its successful deployment in communication-only systems, could be a promising approach in the emerging DFRC ones. In this article, we investigate the development of the HBF techniques on the DFRC system in a self-contained manner. Specifically, we first introduce the basics of the HBF based DFRC system, where the system model and different receive modes are discussed with focus. Then we illustrate the corresponding design principles, which span from the performance metrics and optimization formulations to the design approaches and our preliminary results. Finally, potential extension and key research opportunities, such as the combination with the reconfigurable intelligent surface, are discussed concisely., This manuscript has not been fully modified

This paper investigates dynamic hybrid beamforming (HBF) for a dual-function radar-communication (DFRC) system, where the DFRC base station (BS) simultaneously serves multiple single-antenna users and senses a target in the presence of multiple clutters. Particularly, we apply a HBF architecture with dynamic subarrays and double phase shifters in the DFRC BS. Aiming at maximizing the radar mutual information, we consider jointly designing the dynamic HBF of the DFRC system, subject to the constraints of communication quality of service (QoS), transmit power, and analog beamformer. To solve the complicated non-convex optimization, an efficient alternating optimization algorithm based on the majorization-minimization methods is developed. Simulation results verify the advancement of the considered HBF architecture and the effectiveness of the proposed design method.

As a cost-effective alternative, hybrid analog and digital beamforming architecture is a promising scheme for millimeter wave (mmWave) system. This paper considers two hybrid beamforming architectures, i.e. the partially-connected and fully-connected structures, for mmWave dual-function radar communication (DFRC) system, where the transmitter communicates with the downlink users and detects radar targets simultaneously. The optimization problems are formulated by minimizing a weighted summation of radar and communication performance, subject to constant modulus and power constraints. To tackle the non-convexities caused by the two resultant problems, effective Riemannian optimization algorithms are proposed. Specifically, for the fully-connected structure, a manifold algorithm based on the alternating direction method of multipliers (ADMM) is developed. While for the partially-connected structure, a low-complexity Riemannian product manifold trust region (RPM-TR) algorithm is proposed to approach the near-optional solution. Numerical simulations are provided to demonstrate the effectiveness of the proposed methods.

Our task is to remove all facial parts (e.g., eyebrows, eyes, mouth and nose), and then impose visual elements onto the ``blank'' face for augmented reality. Conventional object removal methods rely on image inpainting techniques (e.g., EdgeConnect, HiFill) that are trained in a self-supervised manner with randomly manipulated image pairs. Specifically, given a set of natural images, randomly masked images are used as inputs and the raw images are treated as ground truths. Whereas, this technique does not satisfy the requirements of facial parts removal, as it is hard to obtain ``ground-truth'' images with real ``blank'' faces. To address this issue, we propose a novel data generation technique to produce paired training data that well mimic the ``blank'' faces. In the mean time, we propose a novel network architecture for improved inpainting quality for our task. Finally, we demonstrate various face-oriented augmented reality applications on top of our facial parts removal model. The source codes are released at \href{https://github.com/duxingren14/FaceEraser}{duxingren14/FaceEraser} on github for research purposes., Comment: 18 pages, 15 figures. ICCV 2021, Fifth Workshop on Computer Vision for AR/VR

To address the problem of target detection in distributed MIMO radar, three styles of distributed MIMO radar systems are given in this paper. With respect to the geometric distribution relations of distributed MIMO radar, the styles are distributed coherent MIMO radar, random phase MIMO radar, and random amplitude-phase MIMO radar. Next, the square law detector structures of random phase and random amplitude-phase MIMO radar are derived in the paper when there is a low signal-to-noise ratio, and the performance of the two detectors are analyzed as well. Finally, simulation results demonstrate the theoretical analysis of this paper are of guiding significance for the actual engineering.

Only a subset of transmitters and receivers in a distributed Multi-Input Multi-Output (MIMO) radar network is allowed to actively track a target at a particular instance due to the limited time and energy resource of a MIMO radar network. It is therefore desirable to obtain an efficient method to overcome the resource constraints while optimizing the tracking performance. In this study, posterior Cramer-Rao lower bound is used as the performance metric and the selection problem is formulated as a Boolean programming problem aiming at optimizing the worst tracking performance of multiple targets. It is later relaxed to a semidefinite programming and solved by the block coordinate descend method. Numerical results show that proposed method superior to the fixed selection method. In addition, with less computation complexity, the proposed method obtains nearly equivalent performance compared with exhaustive search method.

A novel resonant linear piezoelectric motor based on a synchronized switching stimulated by harmonic synthesized mechanical square wave was designed in this study. The driving mechanism of the motor was also investigated. The periodic square wave motions of the clutch and the vibrator were generated by composing two sinusoidal resonant bending vibrations with a frequency ratio of 1:3. The linear motion of the motor output shaft can be realized through the cooperation between the clutch and the vibrator. An experimental device was established to validate the working principle and evaluate the performance of the motor. The prototype motor reached the maximum no-load velocity of 16.35 mm/s with a clutch driving voltage of 200 Vp-p and a vibrator driving voltage of 240 Vp-p for a base frequency of 809 Hz. The maximum traction force of 5.64 N was obtained under the clutch driving voltage of 200 Vp-p and the vibrator driving voltage of 160 Vp-p for a base frequency of 809 Hz. The motor achieved a net efficiency of 21.43% with a load of 2.25 N.

This thesis sets out an introduction to catalysis, particularly heterogeneous gold catalysis, the development of direct synthesis of hydrogen peroxide and benzyl alcohol oxidation by supported bimetallic gold-palladium catalysts. In addition the possibility of combining those two processes together to carry out the benzyl alcohol oxidation using in situ generated hydrogen peroxide.\ud The experimental chapter shows the detailed operation of preparing and testing of catalysts in particular for the reactions studied(H2O2formation, CO oxidation and benzyl alcohol oxidation).\ud In the results and discussion section, some basic knowledge of gold and palladium catalysis is reviewed including some popular preparation methods, the operation of the reactors, and testing in both direct synthesis of hydrogen peroxide and low-temperature CO oxidation. Afterwards, results of gold-palladium catalysis in the oxidation of benzyl alcohol using a mixture of hydrogen and oxygen are shown. In detail, some improvements for the reaction conditions, including temperature and duration, and catalysts, including gold and palladium ratios in alloys and the effect of preparation methods are discussed. In conclusion, higher reaction temperature (75oC) and longer reaction time (2 hours) seemed to be beneficial to converting benzyl alcohol to benzaldehyde by in situ generatedH2O2. Moreover, sol-immobilized1 wt% Au-Pd/TiO2with gold palladium ratio of 1:1 achieved the highest benzyl alcohol conversion and benzaldehyde selectivity among all samples with different metal ratios by different preparation methods.