Sensing-assisted Robust SWIPT for Mobile Energy Harvesting Receivers

Simultaneous wireless information and power transfer (SWIPT) has been proposed to offer communication services and transfer power to the energy harvesting receiver (EHR) concurrently. However, existing works mainly focused on static EHRs, without considering the location uncertainty caused by the movement of EHRs and location estimation errors. To tackle this issue, this paper considers the sensing-assisted SWIPT design in a networked integrated sensing and communication (ISAC) system in the presence of location uncertainty. A two-phase robust design is proposed to reduce the location uncertainty and improve the power transfer efficiency. In particular, each time frame is divided into two phases, i.e., sensing and WPT phases, via time-splitting. The sensing phase performs collaborative sensing to localize the EHR, whose results are then utilized in the WPT phase for efficient WPT. To minimize the power consumption with given communication and power transfer requirements, a two-layer optimization framework is proposed to jointly optimize the time-splitting ratio, coordinated beamforming policy, and sensing node selection. Simulation results validate the effectiveness of the proposed design and demonstrate the existence of an optimal time-splitting ratio for given location uncertainty

Integrated Sensing and Communication in Coordinated Cellular Networks

Integrated sensing and communication (ISAC) has recently merged as a promising technique to provide sensing services in future wireless networks. In the literature, numerous works have adopted a monostatic radar architecture to realize ISAC, i.e., employing the same base station (BS) to transmit the ISAC signal and receive the echo. Yet, the concurrent information transmission causes severe self-interference (SI) to the radar echo at the BS which cannot be effectively suppressed. To overcome this difficulty, in this paper, we propose a coordinated cellular network-supported multistatic radar architecture to implement ISAC. In particular, among all the coordinated BSs, we select a BS as the multistatic receiver to receive the sensing echo signal, while the other BSs act as the multistatic transmitters to collaborate with each other to facilitate cooperative ISAC. This allows us to spatially separate the ISAC signal transmission and radar echo reception, intrinsically circumventing the problem of SI. To this end, we jointly optimize the transmit and receive beamforming policy to minimize the sensing beam pattern mismatch error subject to both the communication and sensing quality-of-service requirements. The resulting non-convex optimization problem is tackled by a low-complexity alternating optimization-based suboptimal algorithm. Simulation results showed that the proposed scheme outperforms the two baseline schemes adopting conventional designs. Moreover, our results confirm that the proposed architecture is promising in achieving high-quality ISAC.Comment: 6 pages, 3 figure

On the Measurements of Individual Particle Properties Via Compression and Crushing

An experimental study is presented to measure the elastic, yielding, and crushing properties of individual particles under compression using substrates made of aluminum alloy, stainless steel, and sapphire. Carefully selected, highly spherical individual Ottawa sand particles of 0.75-1.1 mm in nominal diameter were compressed between two smooth substrates, and the load-deformation curves were analyzed by Hertz elastic contact theory to derive their reduced modulus and Young\u27s modulus as well as yielding and crushing strengths, which vary significantly with the type of substrate materials. Further analysis of the yielding and plastic deformation at the particle-substrate contact shows that the yield strength or hardness of the substrate materials dominates the local contact behavior and hence affects the measured apparent yielding and crushing strengths. The two softer substrates (aluminum alloy and stainless steel) actually lead to underestimated apparent shear yield strengths of quartz particles by 60.4% and 54.2%, respectively, which are actually the yielding of substrates, while the true particle yielding occurs in the sapphire-particle contact. Moreover, the two softer substrates cause much overestimated crushing strengths of the quartz particles by 50.4% and 36.4%, respectively. Selection of inappropriate substrate materials and inappropriate interpretation of the particle-substrate contact can lead to significant errors in the measured yielding and crushing strengths. It is recommended that single particle compression testing uses substrates with yield strength greater than that of the tested particles and result interpretation also considers the elastic and yielding behaviors of the substrates. (C) 2021 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting by Elsevier B.V

Construction of magnetic BiOBr@Fe3O4 hybrid nanoparticles via a sol-gel route for photocatalysis application

663-673Development of a highly active visible-light-driven and magnetically recyclable photocatalyst is a challenge for chemical use of solar energy. In this study, Fe3O4 nanoparticles (NP), BiOBr and a superior magnetic separable BiOBr@Fe3O4 hybrid material have been synthesized via a facile chemical method. The structures, morphological, optical and physical properties of as-synthesized samples have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier transforminfrared (FT-IR) spectroscopy, photoluminescence (PL) spectroscopy. The photocatalytic activity of the as-synthesized materials is evaluated by photocatalytic degradation of aromatic, heterocyclic organic compound such as methylene blue (MB) and 85% of MB could be removed by BiOBr@Fe3O4 hybrid within 60 min. It is found that the composite yield a significantly larger amount of hydroxyl radicals through free radical scavenging test. It is proposed that the observed synergistic effect between Fe3O4 and BiOBr is due to the charge transfer between the two oxides, improving the separation of the photogenerated charge carriers via the Z-scheme mechanism, and thus accelerating the photocatalytic degradation of MB and leading to high photocatalytic stability of BiOBr@Fe3O4 material

Interference Mitigation for Network-Level ISAC: An Optimization Perspective

Future wireless networks are envisioned to simultaneously provide high data-rate communication and ubiquitous environment-aware services for numerous users. One promising approach to meet this demand is to employ network-level integrated sensing and communications (ISAC) by jointly designing the signal processing and resource allocation over the entire network. However, to unleash the full potential of network-level ISAC, some critical challenges must be tackled. Among them, interference management is one of the most significant ones. In this article, we build up a bridge between interference mitigation techniques and the corresponding optimization methods, which facilitates efficient interference mitigation in network-level ISAC systems. In particular, we first identify several types of interference in network-level ISAC systems, including self-interference, mutual interference, crosstalk, clutter, and multiuser interference. Then, we present several promising techniques that can be utilized to suppress specific types of interference. For each type of interference, we discuss the corresponding problem formulation and identify the associated optimization methods. Moreover, to illustrate the effectiveness of the proposed interference mitigation techniques, two concrete network-level ISAC systems, namely coordinated cellular network-based and distributed antenna-based ISAC systems, are investigated from interference management perspective. Experiment results indicate that it is beneficial to collaboratively employ different interference mitigation techniques and leverage the network structure to achieve the full potential of network-level ISAC. Finally, we highlight several promising future research directions for the design of ISAC systems.Comment: 7 pages, 6 figures, and the relevant simulation code can be found at https://dongfang-xu.github.io/homepage/code/Two_cases.zi

Pregnane X receptor is required for interleukin-6-mediated down-regulation of cytochrome P450 3A4 in human hepatocytes

Cytochrome P450 3A4 (CYP3A4) is the most abundant cytochrome P450 enzyme in human liver and metabolizes more than 60% of prescribed drugs in human body. Patients with liver conditions such as cirrhosis show increased secretion of cytokines (e.g., interleukin-6) and decreased capacity of oxidation of many drugs. In this study, we provided molecular evidence that cytokine secretion directly contributed to the decreased capacity of oxidative biotransformation in human liver. After human hepatocytes were treated with IL-6, the expression of CYP3A4 decreased at both mRNA and protein levels, so did the CYP3A4 enzymatic activity. Meanwhile, the repression of CYP3A4 by IL-6 occurred after the decrease of pregnane X receptor (PXR) in human hepatocytes. The PXR-overexpressed cells (transfected with human PXR) increased the CYP3A4 mRNA level, and the repression of CYP3A4 by IL-6 was greater in the PXR-overexpressed cells than in the control cells. Further, PXR knockdown (transfected with siPXR construct) decreased the CYP3A4 mRNA level with less repression by IL-6 than in the control cells transfected with corresponding vector. Collectively, our study suggests that PXR is necessary for IL-6-mediated repression of the CYP3A4 expression in human hepatocytes