Optimized Measurement Matrix Design Using Spatiotemporal Chaos for CS-MIMO Radar

We investigate the possibility of utilizing the chaotic dynamic system for the measurement matrix design in the CS-MIMO radar system. The CS-MIMO radar achieves better detection performance than conventional MIMO radar with fewer measurements. For exactly recovering from compressed measurements, we should carefully design the measurement matrix to make the sensing matrix satisfy the restricted isometry property (RIP). A Gaussian random measurement matrix (GRMM), typically used in CS problems, is not satisfied for on-line optimization and the low coherence with the basis matrix corresponding to the MIMO radar scenario can not be well guaranteed. An optimized measurement matrix design method applying the two-dimensional spatiotemporal chaos is proposed in this paper. It incorporates the optimization criterion which restricts the coherence of the sensing matrix and singular value decomposition (SVD) for the optimization process. By varying the initial state of the spatiotemporal chaos and optimizing each spatiotemporal chaotic measurement matrix (SCMM), we can finally obtain the optimized measurement matrix. Its simulation results show that the optimized SCMM can highly reduce the coherence of the sensing matrix and improve the DOA estimation accuracy for the CS-MIMO radar

Authorized and Rogue LTE Terminal Identification Using Wavelet Coefficient Graph with Auto-encoder

The wide popularity of 4G/5G mobile terminals increase the requirements of wireless security. Radio frequency fingerprint (RFF) technology can strengthen 4G/5G air interface accessing security at the physical layer. In this paper, a wavelet transform (WT) coefficient graphs RFF extraction with auto-encoder (AE) based rogue terminal detection scheme is proposed. At first, WT coefficients at 48 scales are extracted from the transient-power-off part of LTE physical random access channel (PRACH) preamble. Then, an AE network structure aimed for 2D WT coefficient graph is designed for rogue terminal detection. We successfully distinguish 7 mobile phones and 1 USRP under the proposed mechanism, where the authorized terminals from the same manufacturer can be identified with an accuracy of 90.08%. In addition, extensive experiments are carried out at LOS and NOLS scenarios, respectively, the proposed LTE identification scheme has demonstrated robustness in dynamic environments

Approximate maximum-likelihood RIS-aided positioning

A reconfigurable intelligent surface (RIS) allows a reflection transmission path between a base station (BS) and user equipment (UE). In wireless localization, this reflection path aids in positioning accuracy, especially when the line-of-sight (LOS) path is subject to severe blockage and fading. In this paper, we develop a RIS-aided positioning framework to locate a UE in environments where the LOS path may or may not be available. We first estimate the RIS-aided channel parameters from the received signals at the UE. To infer the UE position and clock bias from the estimated channel parameters, we propose a fusion method consisting of weighted least squares over the estimates of the LOS and reflection paths. We show that this approximates the maximum likelihood estimator under the large-sample regime and when the estimates from different paths are independent. We then optimize the RIS phase shifts to improve the positioning accuracy and extend the proposed approach to the case with multiple BSs and UEs. We derive Cramer–Rao bound (CRB) and demonstrate numerically that our proposed positioning method approaches the CRB.Agency for Science, Technology and Research (A*STAR)National Research Foundation (NRF)Submitted/Accepted versionThis research was supported by A*STAR under its RIE2020 Advanced Manufacturing and Engineering (AME) Industry Alignment Fund – Pre Positioning (IAF-PP) (Grant No. A19D6a0053), and the National Research Foundation, Singapore and Infocomm Media Development Authority under its Future Communications Research and Development Programme

A novel multiplex PCR assay for species identification in the Chinese Egret (Egretta eulophotes) and Little Egret (E garzetta)

National Natural Science Foundation of China [30970380, 31000621, 31000963, 40876077, J1030626]; Fujian or Henan Natural Science Foundation of China [2010Y2007, 2010J05084, 2009J01195, 102102110180]A multiplex PCR assay is described herein for the species identification of juvenile egrets, Chinese Egret (Egretta eulophotes) and Little Egret (E. garzetta), which colonially breed in a heronary and share similar exterior characteristics. In this new assay, the primers were designed to yield to a 101 bp positive control amplicon of partial ND6 and tRNA(Glu) gene, and the species-specific primers were designed for species identification in E. eulophotes and E. garzetta (partial ND6 and Control Region gene, about 278 and 302 bp, respectively). Using simple agarose gel electrophoresis the PCR products discriminates the two species unambiguously indicated that our new assay could be used for accurate and convenient species identification in E. eulophotes and E. garzetta

A novel multiplex PCR assay for species identification in the Chinese Egret (Egretta eulophotes) and Little Egret (E garzetta)

National Natural Science Foundation of China [30970380, 31000621, 31000963, 40876077, J1030626]; Fujian or Henan Natural Science Foundation of China [2010Y2007, 2010J05084, 2009J01195, 102102110180]A multiplex PCR assay is described herein for the species identification of juvenile egrets, Chinese Egret (Egretta eulophotes) and Little Egret (E. garzetta), which colonially breed in a heronary and share similar exterior characteristics. In this new assay, the primers were designed to yield to a 101 bp positive control amplicon of partial ND6 and tRNA(Glu) gene, and the species-specific primers were designed for species identification in E. eulophotes and E. garzetta (partial ND6 and Control Region gene, about 278 and 302 bp, respectively). Using simple agarose gel electrophoresis the PCR products discriminates the two species unambiguously indicated that our new assay could be used for accurate and convenient species identification in E. eulophotes and E. garzetta

Using Medium-Resolution Remote Sensing Satellite Images to Evaluate Recent Changes and Future Development Trends of Mangrove Forests on Hainan Island, China

Mangroves are endemic forest communities in tropical and subtropical coastal zones. China’s Hainan Island is very rich in mangrove plant species. In recent years, due to climate change and human disturbance, the living environment of many mangrove distribution areas has been seriously threatened. This study used land satellite series remote sensing images from 1990 to 2020 to monitor the coverage and area changes of mangroves on Hainan Island. The spatial distribution pattern and change trend of mangroves were explored using the standard deviation ellipse method, and the CA–Markov model was used to predict the possible changes of mangroves in the study area in 2025 and 2030. The development trend of mangroves in the future and the driving factors affecting the evolution of mangroves were also analyzed. Over the past 30 years, the area of mangroves has witnessed fluctuations. It decreased from 4578 hectares in 1990 to its lowest at 3870 hectares in 2005 and then rebounded to 4474 hectares by 2020, indicating an initial decline followed by a gradual increase. Although conservation and restoration efforts have yielded success, specific areas have witnessed a decline in mangrove coverage. From 1990 to 2020, mangrove areas in Huiwen decreased from 1055 hectares to 904 hectares, areas in Guannan decreased from 227 hectares to 167 hectares, areas in Xinyinggang decreased from 328 hectares to 298 hectares, areas in Yangpugang decreased from 747 hectares to 682 hectares, areas in Huachangwan decreased from 355 hectares to 327 hectares, and areas in Puqian decreased from 170 hectares to 141 hectares. In particular, the growth in the Eastern and Mayao port areas is especially significant. Additionally, data analysis has revealed the spatial distribution characteristics of mangroves in different regions, such as the mangrove area in Dongzhaigang, which remained relatively stable from 1990 to 2020, while in other areas like Huiwen and Guannan, the mangrove area decreased during these 20 years. By calculating the standard deviation ellipse, we observed that the overall change of mangroves on Hainan Island from 1990 to 2020 was relatively slow, mainly distributed along the northern coastal area of Hainan Island. Furthermore, the standard deviation ellipse and SDE center point of each mangrove growth area have visualized the growth trends of the mangroves. The Markov chain simulation results show that future changes in mangroves will mainly be concentrated in the marginal areas of the mangroves. These areas may be affected by rising sea levels, climate change, soil salinity, and human activities. In the future, mangrove areas are expected to display a dynamic equilibrium, experiencing periods of expansion and reduction, ultimately moving towards a more consistent state. To protect and restore mangroves, it is necessary to strengthen the monitoring and management of their ecological environment and socio-economic factors and improve their stability and diversity

Nisin-loaded polydopamine/hydroxyapatite composites

Microbial contamination caused by bacterial adhesion and colonization onto the materials surfaces has long been a serious threat to human health. Thus, it is imperative to develop advanced antimicrobial materials for bio-applications. Here, a unique polydopamine/ hydroxyapatite/nisin (PDA/HAP/Nisin) composite with good bioactivities and enhanced antibacterial activities have been developed. The uniform PDA particles are first prepared via the dopamine self-polymerization in an alkaline water-ethanol mixed solvent. Due to the abundance surface catecholamine moieties, PDA particles can serve as the powerful templates for the in-situ mineralization of hydroxyapatite (HAP) in a simulated body fluid (SBF) solution, forming PDA/HAP composites. Transmission electron microscopy, scanning electron microscopy, transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction are used to investigate the morphology, surface composition, and crystalline structure of the PDA/HAP composites. These PDA/HAP composites are utilized as the reservoir for loading the antimicrobial peptide–nisin. Ultraviolet visible spectrophotometry analysis shows that PDA/HAP composites have exhibited a high loading capacity and a superior loading efficiency for nisin. The resulting PDA/HAP/Nisin composites are ideal antimicrobial biomaterials for bio-application because they exhibit not only a significant in vitro cytocompatibility to human embryonic kidney HEK293 T cells, but also the enhanced antibacterial activities against Staphylococcus aureus (Gram-positive bacteria). These advantageous properties of the PDA/HAP/Nisin composites allow them as the promising candidates for a broad range of bio-applications, e.g., drug delivery, implant engineering, and bio-scaffold.Peer reviewe

Evaluation of the distribution of N, P and organic matter in sediment and the pollution status of Lakes in southeastern Hubei Province, China

AbstractEutrophication caused by nutrients and organic matter (OM) pollution is a common problem in the world. The contents of total nitrogen (TN), total phosphorus (TP) and OM in sediments were determined in four typical lakes in southeastern Hubei, China, in the spring of 2019, and their pollution status was evaluated by organic and comprehensive pollution indexes to identify pollution sources and provide specific directions for the pollution control in key areas of the lakes. We found the following: (1) Both nutrients and OM in Cihu Lake and Bao’an Lake were relatively high. Cihu Lake had the highest nutrient and OM in both surface and core sediments. TN, TP and OM in the surface sediments of Cihu Lake reached 700.9 mg/kg, 1668.8 mg/kg and 62.8 kg/g, respectively. The contents of nutrients and OM in Daye Lake and Liangzi Lake were relatively low. OM in these two lakes was significantly lower than that in the Cihu Lake (p  0.05). It indicated that the sources of nutrients and OM in sediments were not identical but were affected by many factors. However, the relationship between nutrients and OM was closer in core sediments. In the future, targeted measures should be taken to reduce sediment pollution based on specific pollution sources and pollution conditions in the four lakes, especially Cihu Lake

Etching-Assisted Route to Heterophase Au Nanowires with Multiple Types of Active Surface Sites for Silane Oxidation

The construction of multiple types of active sites on the surface of a metallic catalyst can markedly enhance its catalytic activity toward specific reactions. Here, we show that heterophase gold nanowires (Au NWs) with multiple types of active surface sites can be synthesized using an etching-assisted process, yielding the highest reported turnover frequency (TOF) for Au catalysts toward the silane oxidation reaction by far. We use synchrotron powder X-ray diffraction (PXRD) and aberration-corrected (scanning) transmission electron microscopy (TEM) to show that the Au NWs contain heterophase structures, planar defects, and surface steps. Moreover, the contribution to the catalytic performance from each type of active sites was clarified. Surface steps on the Au NW catalysts, which were identified using aberration-corrected (scanning) TEM, were shown to play the most important role in enhancing the catalytic performance. By using synchrotron PXRD, it was shown that a small ratio of metastable phases within Au NWs can enhance catalytic activity by a factor of 1.35, providing a further route to improve catalytic activity. Of the three types of surface active sites, surface terminations of planar defects such as twin boundaries (TB) and stacking faults (SF) are less active than metastable phases and surface steps for Au catalysts toward the silane oxidation reaction. Such an etching-assisted synthesis of heterophase Au NWs promises to open new possibilities for catalysis, plasmonic, optics, and electrical applications