Per-Antenna Self-Interference Cancellation Beamforming Design for Digital Phased Array

Almost all current beamforming-based designs of self-interference cancellation (SIC) for digital phased array systems neglect the practical issue of the limited dynamic range of analog-to-digital converters (ADCs) and, thus, lack restriction for self-interference (SI) that is incident at each receiving antenna. Other than beamforming, these methods usually require additional SIC techniques to provide a part of isolation, which brings higher system complexity. In this letter, a SIC method is proposed to overcome these issues. By developing a transmit SIC beamformer design that minimizes the power of SI on a per-antenna basis, we can obtain more isolation before the ADCs in each receiving channel and better prevent them all from being saturated. Then, the residual SI can be further suppressed by adaptive receive beamformers to achieve high total isolation performance. The proposed method reduces the need for other SIC techniques than beamforming technology in phased array systems and, thus, facilitates lower system complexity. Numerical results demonstrate the effectiveness of the proposed method.acceptedVersionPeer reviewe

Deep Domain Adaptation for Pavement Crack Detection

Deep learning-based pavement cracks detection methods often require large-scale labels with detailed crack location information to learn accurate predictions. In practice, however, crack locations are very difficult to be manually annotated due to various visual patterns of pavement crack. In this paper, we propose a Deep Domain Adaptation-based Crack Detection Network (DDACDN), which learns to take advantage of the source domain knowledge to predict the multi-category crack location information in the target domain, where only image-level labels are available. Specifically, DDACDN first extracts crack features from both the source and target domain by a two-branch weights-shared backbone network. And in an effort to achieve the cross-domain adaptation, an intermediate domain is constructed by aggregating the three-scale features from the feature space of each domain to adapt the crack features from the source domain to the target domain. Finally, the network involves the knowledge of both domains and is trained to recognize and localize pavement cracks. To facilitate accurate training and validation for domain adaptation, we use two challenging pavement crack datasets CQU-BPDD and RDD2020. Furthermore, we construct a new large-scale Bituminous Pavement Multi-label Disease Dataset named CQU-BPMDD, which contains 38994 high-resolution pavement disease images to further evaluate the robustness of our model. Extensive experiments demonstrate that DDACDN outperforms state-of-the-art pavement crack detection methods in predicting the crack location on the target domain.Comment: 12 pages, 10 figure

Magmatic record of India-Asia collision

This work was financially co-supported by Chinese Academy of Sciences (XDB03010301) and other Chinese funding agencies (Project 973: 2011CB403102 and 2015CB452604; NSFC projects: 41225006, 41273044, and 41472061).New geochronological and geochemical data on magmatic activity from the India-Asia collision zone enables recognition of a distinct magmatic flare-up event that we ascribe to slab breakoff. This tie-point in the collisional record can be used to back-date to the time of initial impingement of the Indian continent with the Asian margin. Continental arc magmatism in southern Tibet during 80-40 Ma migrated from south to north and then back to south with significant mantle input at 70-43 Ma. A pronounced flare up in magmatic intensity (including ignimbrite and mafic rock) at ca. 52-51 Ma corresponds to a sudden decrease in the India-Asia convergence rate. Geological and geochemical data are consistent with mantle input controlled by slab rollback from ca. 70 Ma and slab breakoff at ca. 53 Ma. We propose that the slowdown of the Indian plate at ca. 51 Ma is largely the consequence of slab breakoff of the subducting Neo-Tethyan oceanic lithosphere, rather than the onset of the India-Asia collision as traditionally interpreted, implying that the initial India-Asia collision commenced earlier, likely at ca. 55 Ma.Publisher PDFPeer reviewe

1-Diphenyl­phosphino-1′-(diphenyl­phosphinoyl)cobaltocenium hexa­fluorido­phosphate

The title compound, [Co(C17H14OP)(C17H14P)]PF6, was obtained unintentionally as the product of an attempted synthesis of [1,1′-bis­(oxodiphenyl­phospho­ranyl)cobaltocenium] hexa­fluorido­phosphate. The O atom of the oxo group is disordered over two positions with site occupancies of 0.65:0.35. The crystal structure contains weak inter­molecular C—H⋯F hydrogen bonds, connecting the components of the structure into chains parallel to [010]

(+)-N-[2-(4-Chloro­phen­yl)propano­yl]bornane-10,2-sultam

In the mol­ecular structure of the title compound, C19H24ClNO3S, the six-membered ring of the bornane unit shows a boat form, while the five-membered ring of the sultam unit adopts a twist form. Intra­molecular C—H⋯N and C—H⋯O inter­actions are observed. In the crystal structure, mol­ecules are connected by inter­molecular C—H⋯O hydrogen bonds into a chain running along the b axis. The crystal was a partial inversion twin with a twin ratio of 0.73 (1):0.27 (1)

Assembly of the Lhasa and Qiangtang terranes in central Tibet by divergent double subduction

This research was financially co-supported by the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (XDB03010301), the National Key Project for Basic Research of China (2011CB403102 and 2015CB452604), the Chinese National Natural Science Foundation (41225006, 41472061, and 40973026), and the Specialized Research Fund for the Doctoral Program of Higher Education (20120022110001)Integration of lithostratigraphic, magmatic, and metamorphic data from the Lhasa-Qiangtang collision zone in central Tibet (including the Bangong suture zone and adjacent regions of the Lhasa and Qiangtang terranes) indicates assembly through divergent double sided subduction. This collision zone is characterized by the absence of Early Cretaceous high-grade metamorphic rocks and the presence of extensive magmatism with enhanced mantle contributions at ca. 120–110 Ma. Two Jurassic−Cretaceous magmatic arcs are identified from the Caima−Duobuza−Rongma−Kangqiong−Amdo magmatic belt in the western Qiangtang Terrane and from the Along Tso−Yanhu−Daguo−Baingoin−Daru Tso magmatic belt in the northern Lhasa Terrane. These two magmatic arcs reflect northward and southward subduction of the Bangong Ocean lithosphere, respectively. Available multidisciplinary data reconcile that the Bangong Ocean may have closed during the Late Jurassic−Early Cretaceous (most likely ca. 140–130 Ma) through arc-arc “soft” collision rather than continent-continent “hard” collision. Subduction zone retreat associated with convergence beneath the Lhasa Terrane may have driven its rifting and separation from the northern margin of Gondwana leading to its accretion within Asia.PostprintPeer reviewe

Multistep oxidation of diethynyl oligophenylamine-bridged diruthenium and diiron complexes

Homodinuclear nonlinear complexes [{M(dppe)Cp*}2{μ-(-C≡C)2X}] (X = triphenylamine (TPA), M = Ru (1a) and Fe (1b); X = N,N,N',N',-tetraphenylphenylene-1,4-diamine (TPPD), M = Ru (2a)) were prepared and characterized by 1H, 13C and 31P NMR and single crystal X-ray diffraction (1a, 2a). Attempts to prepare the diiron analogue of 2a were not successful. Experimental data obtained from cyclic voltammetry (CV), square wave voltammetry (SWV), UV-vis-NIR spectroelectrochemistry and very informative IR spectroelectrochemistry in the C≡C-stretching region, combined with density functional theory calculations, afford to make an emphasizing assessment of the close association between the metal‒ethynyl termini and the oligophenylamine bridge core as well as their respective involvement in sequential one-electron oxidations of these complexes. The anodic behavior of the homobimetallic complexes depends strongly both on the metal center and the length of the oligophenylamine bridge core. The poorly separated first two oxidations of diiron complex 1b are localized on the electronically nearly independent Fe termini. In contrast, diruthenium complex 1a exhibits a significantly delocalized character and a marked electronic communication between the ruthenium centers through the diethynyl-TPA bridge. The ruthenium-ethynyl halves in 2a, separated by the doubly extended and more flexible TPPD bridge core, show a lower degree of electronic coupling, resulting in close-lying first two anodic waves and the NIR electronic absorption of [2a]+ with an indistinctive IVCT character. Finally, the third anodic waves in the voltammetric responses of the homobimetallic complexes are associated with the concurrent exclusive oxidation of the TPA or TPPD bridge cores