Interchannel Interference and Mitigation in Distributed MIMO RF Sensing.

In this paper, we analyze and mitigate the cross-channel interference, which is found in multiple-input multiple-output (MIMO) radio frequency (RF) sensing systems. For a millimeter wave (mm-Wave) MIMO system, we present a geometrical three-dimensional (3D) channel model to simulate the time-variant (TV) trajectories of a moving scatterer. We collected RF data using a state-of-the-art radar known as Ancortek SDR-KIT 2400T2R4, which is a frequency-modulated continuous wave (FMCW) MIMO radar system operating in the K-band. The Ancortek radar is currently the only K-band MIMO commercial radar system that offers customized antenna configurations. It is shown that this radar system encounters the problem of interference between the various subchannels. We propose an optimal approach to mitigate the problem of cross-channel interference by inducing a propagation delay in one of the channels and apply range gating. The measurement results prove the effectiveness of the proposed approach by demonstrating a complete elimination of the interference problem. The application of the proposed solution on Ancortek's SDR-KIT 2400T2R4 allows resolving all subchannel links in a distributed MIMO configuration. This allows using MIMO RF sensing techniques to track a moving scatterer (target) regardless of its direction of motion.

Optimizing 3D Convolution Kernels on Stereo Matching for Resource Efficient Computations.

Despite recent stereo matching algorithms achieving significant results on public benchmarks, the problem of requiring heavy computation remains unsolved. Most works focus on designing an architecture to reduce the computational complexity, while we take aim at optimizing 3D convolution kernels on the Pyramid Stereo Matching Network (PSMNet) for solving the problem. In this paper, we design a series of comparative experiments exploring the performance of well-known convolution kernels on PSMNet. Our model saves the computational complexity from 256.66 G MAdd (Multiply-Add operations) to 69.03 G MAdd (198.47 G MAdd to 10.84 G MAdd for only considering 3D convolutional neural networks) without losing accuracy. On Scene Flow and KITTI 2015 datasets, our model achieves results comparable to the state-of-the-art with a low computational cost.

Ultrahigh-Mobility and Solution-Processed Inorganic P-Channel Thin-Film Transistors Based on a Transition-Metal Halide Semiconductor.

The development of p-channel devices with comparable electrical performances to their n-channel counterparts has been delayed due to the lack of p-type semiconductor materials and device optimization. In this present work, we successfully demonstrated p-channel inorganic thin-film transistors (TFTs) with high hole mobilities similar to the values of n-channel devices. To boost the device performance, the solution-processed copper iodide (CuI) semiconductor was gated by a solid polymer electrolyte. The electrolyte gating could realize electrical double layer (EDL) formation and a three-dimensional carrier transport channel and thus substantially increased charge accumulation in the channel region and realized a high mobility above 90 cm2/(V s) (45.12 ± 22.19 cm2/(V s) on average). In addition, due to the high-capacitance EDL formed by electrolyte gating, the CuI TFTs exhibited a low operation voltage below 0.5 V (Vth = -0.045 V) and a high ON current level of 0.7 mA with an ON/OFF ratio of 1.52 × 103. We also evaluated the operational stabilities of CuI TFTs and the devices showed 80% retention under electrical/mechanical stress. All the active layers of the transistors were fabricated by solution processes at low temperatures (<100 °C), indicating their potential use for flexible, wearable, and high-performance electronic applications.

A Versatile Method for Fabricating Tissue Engineering Scaffolds with a Three-Dimensional Channel for Prevasculature Networks.

Despite considerable advances in tissue engineering over the past two decades, solutions to some crucial problems remain elusive. Vascularization is one of the most important factors that greatly influence the function of scaffolds. Many research studies have focused on the construction of a vascular-like network with prevascularization structure. Sacrificial materials are widely used to build perfusable vascular-like architectures, but most of these fabricated scaffolds only have a 2D plane-connected network. The fabrication of three-dimensional perfusable branched networks remains an urgent issue. In this work, we developed a novel sacrificial molding technique for fabricating biocompatible scaffolds with a three-dimensional perfusable branched network. Here, 3D-printed poly(vinyl alcohol) (PVA) filament was used as the sacrificial material. The fused PVA was deposited on the surface of a cylinder to create the 3D branched solid network. Gelatin was used to embed the solid network. Then, the PVA mold was dissolved after curing the hydrogel. The obtained architecture shows good perfusability. Cell experiment results indicated that human umbilical vein endothelial cells (HUVECs) successfully attached to the surface of the branched channel and maintained high viability after a few days in culture. In order to prevent deformation of the channel, paraffin was coated on the surface of the printed structure, and hydroxyapatite (HA) was added to gelatin. In conclusion, we demonstrate a novel strategy toward the engineering of prevasculature thick tissues through the integration of the fused PVA filament deposit. This approach has great potential in solving the issue of three-dimensional perfusable branched networks and opens the way to clinical applications.