Differential Sonar

Sonar is used to track in-room activity. A sonar device provides acoustic location and tracking of multiple objects that are co-present in a room. A sender/receiver in the sonar device directs a sound wave toward the multiple objects and collects the reflected sound waves from the multiple objects over multiple time intervals. The echo characteristics of the co-present multiple objects in the reflected sound waves collected over the multiple time intervals are differentially analyzed to determine the locations of, and track movement of, individual objects of the multiple objects

First-principle Studies on Ferromagnetism of Fe-doped AlN Diluted Magnetic Semiconductors

We have studied the electronic structures and magnetic properties of Fe-doped AlN by first-principles calculations within density functional theory. The calculated results show that AlN crystals doped by double Fe atoms display ferromagnetic properties, and the total magnetic moment is 10.0 μB per 72-atom supercell (3 × 3 × 2). The calculated energy differences between the antiferromagnetic (AFM) and ferromagnetic (FM) phases are 207 meV, which means FM state is a stable state. It is also found that the 3d-states of Fe dopants and the 2p-states of N atoms bonding to Fe dopants are the main contributors to the density of states at the Fermi level

LightFR: Lightweight Federated Recommendation with Privacy-preserving Matrix Factorization

Federated recommender system (FRS), which enables many local devices to train a shared model jointly without transmitting local raw data, has become a prevalent recommendation paradigm with privacy-preserving advantages. However, previous work on FRS performs similarity search via inner product in continuous embedding space, which causes an efficiency bottleneck when the scale of items is extremely large. We argue that such a scheme in federated settings ignores the limited capacities in resource-constrained user devices (i.e., storage space, computational overhead, and communication bandwidth), and makes it harder to be deployed in large-scale recommender systems. Besides, it has been shown that transmitting local gradients in real-valued form between server and clients may leak users' private information. To this end, we propose a lightweight federated recommendation framework with privacy-preserving matrix factorization, LightFR, that is able to generate high-quality binary codes by exploiting learning to hash technique under federated settings, and thus enjoys both fast online inference and economic memory consumption. Moreover, we devise an efficient federated discrete optimization algorithm to collaboratively train model parameters between the server and clients, which can effectively prevent real-valued gradient attacks from malicious parties. Through extensive experiments on four real-world datasets, we show that our LightFR model outperforms several state-of-the-art FRS methods in terms of recommendation accuracy, inference efficiency and data privacy.Comment: Accepted by ACM Transactions on Information Systems (TOIS

Preparation and characterization of a sulfonated carbon-based solid acid microspheric material (SCSAM) and its use for the esterification of oleic acid with methanol

In this study, a sulfonated group (-SO3H) rich carbon-based solid acid microspheric material was prepared by hydrothermal method followed by sulfonation using glucose as the raw material. Such a green, non-corrosive, and renewable carbon material was used as a heterogeneous catalyst for the esterification of oleic acid with methanol for the production of biodiesel. The carbon microspheres were characterized systematically. It was found that the carbon microspheres prepared under the optimal reaction conditions exhibited smooth surfaces, uniform particle sizes and good dispersion. The sulfonated carbon-based solid acid microspheric materials showed high acidity and good catalytic activities for the esterification of oleic acid with methanol. The influence of reaction operating conditions on the performance of esterification was studied. The optimal esterification reaction conditions were found to be: methanol/oleic acid molar ratio 12:1, catalyst loading 0.25 g (0.05 mmol H+), reaction temperature 65 °C, reaction time 8 h and mechanical stirring rate 360 rpm. It was found that the catalyst demonstrated very good reusability although there was noticeable loss in acidity due to the leaching of active sites

Autofocus Analysis: Latency and Sharpness

In this study a new camera testing method is introduced to determine and analyze the autofocus latency of cameras. This analysis allows for objective comparison and tuning of autofocus algorithms in order to deliver both sharp images and the optimal user experience with a camera. Given images taken in variable illuminance conditions with different methods of focus reset, along with high-speed recordings of the camera viewfinder throughout the reset and capture, machine vision is used to extract three different types of latencies: The first latency is the autofocus time, which is measured from the end of the focus reset to full stability, as measured by slanted-edge sharpness in the camera viewfinder. The next latency is the user interface latency, which also comes from the viewfinder and is the time between the camera trigger and when the user interface of the camera indicates that a capture took place. The final latency is the captured image latency, which is taken from the captured image itself and is the time between the camera trigger and when the image is actually captured. In addition, we measure the sharpness of the final captured image in each test. Commercially available smartphone devices were tested using this method, showing significantly different results in both latency and sharpness measurements and uncovering trends in sharpness-latency trade-offs

Highly efficient steam reforming of ethanol (SRE) over CeO x grown on the nano Ni x Mg y O matrix: H 2 production under a high GHSV condition

Steam reforming of ethanol (SRE) over non-noble metal catalysts is normally conducted at high temperature (>600°C) to thermodynamically favour the catalytic process and carbon deposition mitigation. However, high temperature inhibits water-gas shift reaction (WGSR) and therefore restrains the yield of H2 and leads to the formation of an excessive amount of CO. The modification of non-noble metal catalyst to enhance WGSR is an attractive alternative. In this study, CeOx was firstly loaded onto a nano-scaled NixMgyO matrix and subsequently used as the catalyst for hydrogen production via SRE. Morphology of the catalyst materials was characterized by using a series of technologies, while H2-temperature programmed reduction (H2-TPR), CO-temperature programmed deposition (CO-TPD), and X-ray photoelectron spectroscopy (XPS), were employed to study the surface nickel, ceria clusters, and their interactions. The catalytic activity and durability of the catalyst were studied in the temperature region of 500°C to 800°C. The CeOx-coated nano NixMgyO matrix exhibited an outstanding hydrogen yield of 4.82 mol/molethanol under a high gas hourly space velocity (GHSV) of 200 000 hour−1. It is found that the unique Ni0-CeOx structure facilitates the adsorption of CO on the surface and therefore promotes the effective hydrogen production via WGSR. Moreover, this modified NixMgyO matrix was found to be a more robust and anticoking nanocatalyst because of reversible switch between Ce4+ and Ce3+. © 2019 John Wiley & Sons, Ltd

Barrier Inhomogeneity of Schottky Diode on Nonpolar AlN Grown by Physical Vapor Transport

An aluminum nitride (AlN) Schottky barrier diode (SBD) was fabricated on a nonpolar AlN crystal grown on tungsten substrate by physical vapor transport. The Ni/Au-AlN SBD features a low ideality factor n of 3.3 and an effective Schottky barrier height (SBH) of 1.05 eV at room temperature. The ideality factor n decreases and the effective SBH increases at high temperatures. The temperature dependences of n and SBH were explained using an inhomogeneous model. A mean SBH of 2.105 eV was obtained for the Ni-AlN Schottky junction from the inhomogeneity analysis of the current-voltage characteristics. An equation in which the parameters have explicit physical meanings in thermionic emission theory is proposed to describe the current-voltage characteristics of inhomogeneous SBDs.Comment: 6 pages, 6 figure