Off-grid direction-of-arrival estimation for wideband noncircular sources

Xiaoyu Zhang1,Haihong Tao,Ziye Fang,Jian Xie 한국전자통신연구원 2023 ETRI Journal Vol.45 No.3

Researchers have recently shown an increased interest in estimating the direction-of-arrival (DOA) of wideband noncircular sources, but existing studies have been restricted to subspace-based methods. An off-grid sparse recovery-based algorithm is proposed in this paper to improve the accuracy of existing algorithms in low signal-to-noise ratio situations. The covariance and pseudo covariance matrices can be jointly represented subject to block sparsity constraints by taking advantage of the joint sparsity between signal components and bias. Furthermore, the estimation problem is transformed into a single measurement vector problem utilizing the focused operation, resulting in a significant reduction in computational complexity. The proposed algorithm's error threshold and the Cramer–Rao bound for wideband noncircular DOA estimation are deduced in detail. The proposed algorithm's effectiveness and feasibility are demonstrated by simulation results.

A New ent-Kaurane type Diterpenoid Glycoside from Inula japonica Thunb

Jiang Jiang Qin,Jia Xian Zhu,Wei Dong Zhang1,2,Yan Zhu,Jian Jun Fu,Xiao Hua Liu,Hui Zi Jin 대한약학회 2009 Archives of Pharmacal Research Vol.32 No.10

A new ent-kaurane type diterpenoid glycoside, 17-O-β-D-glucopyranosyl-16α-ent-kauran-19-oic acid (1), together with 17-hydroxy-16α-ent-kauran-19-oic acid (2), 16α,17-dihydroxyl-ent-kauran-19-oic acid (3), and 16α-hydroxy-17-acetoxy-ent- kauran-19-oic acid (4) were isolated from the aerial parts of Inula japonica Thunb. The structure of 1 was determined mainly by use of 1D and 2D NMR spectroscopic techniques including HSQC, 1H-1H COSY, HMBC, and NOESY. In addition, 4 exhibited significant inhibitory activity on NO production in LPS-stimulated RAW264.7 cells with IC50 value of 14.3 μg/mL.

Preparation, self-assembly and performance modulation of gold nanoparticles decorated ferrocene-containing hybrid block copolymer multifunctional materials

Jian-Guo Zhang,Xue-Yin Zhang,Hua Yu,Yan-Ling Luo,Feng Xu,Ya-Shao Chen 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.65 No.-

Gold nanoparticles decorated stimuli-responsive copolymer hybrids, poly(2-methacryloyloxyethyl ferrocenecarboxylate)-block-poly(N-isopropylacryamide) decorated with gold nanoparticles, were synthesized through two-step successive RAFT and ensuing in-situ reduction. The hybrids could self-assemble into interesting micelle structures from globular, wormlike to rodlike shapes by altering the quality and compositions of solvents and ionic strength, and exhibited multifunctionality including quasi-reversible electrochemical behavior, redox-stress responsiveness and temperature sensitivity. The physicochemical and electrochemical properties were modulated by tailor-making the system compositions and redox reaction. The copolymer hybrids were expected to broaden their applications in nanobiomedicine including targeted drug carriers and magnetic resonance imaging, optical, electrochemical catalyst, optoelectronics and sensors etc.

The Role of Wheat Germ Agglutinin in the Attachment of Pseudomonas sp. WS32 to Wheat Root

Jian Zhang,Liyuan Meng,Yuanyuan Cao,Huiping Chang,Zhongyou Ma,Leni Sun,Ming Zhang,Xinyun Tang 한국미생물학회 2014 The journal of microbiology Vol.52 No.12

Wheat germ agglutinin (WGA), which is secreted on thesurface of wheat root, has been defined as a protein that reversiblyand non-enzymatically binds to specific carbohydrates. However, little attention has been paid to the functionof WGA in the attachment of bacteria to their host plants. The aim of this study was to investigate the role of WGA inthe attachment of Pseudomonas sp. WS32 to wheat roots. Wheat roots were initially treated with double-distilled water,WGA-H (WGA solution that was heated at 100°C for 15 min)and WGA, independently. Subsequently, the roots were coincubatedwith cell solutions (109 cells/ml). A dilution platemethod using a solid nutrient medium was employed to determinethe adsorption of WS32 to wheat roots. WGA waslabeled with fluorescein isothiocyanate and detected usingthe fluorescent in situ hybridization (FISH) technique. Thenumber of adsorptive WS32 cells on wheat roots was significantlyincreased when the wheat roots were pretreatedwith WGA, compared with the control treatment (p = 0.01). However, WGA-H failed to increase the amount of bacterialcells that attached to the wheat roots because of the lossof its physiological activity. The FISH assay also revealedthat more cells adhered to WGA-treated wheat roots than tocontrol or WGA-H-treated roots. The results indicated thatWGA can mediate Pseudomonas strain WS32’s adherenceto wheat seedling roots. The findings of this study provide abetter understanding of the processes involved in plant-microbe interactions.

Performance investigation of nanoscale thermal cloak by the perforated silicon film

Zhang Jian,Zhang Haochun,Zhang Dong,Sun Wenbo,Li Yiyi 한국물리학회 2022 Current Applied Physics Vol.35 No.-

In recent years, nanoscale thermal cloak, as a representative of nanoscale heat flux regulation devices, has attracted a lot of attention from researchers. However, the existing design methods are relatively complicated and all adopt constant temperature boundaries, the temperature changes constantly in the real environment, which greatly hinders its engineering applications. In this paper, inspired by phonon localization theory, we construct a nanoscale thermal cloak by a perforated silicon membrane and evaluate its cloaking performance and dynamic response. Results show that when the perforated area is fixed, the more the number of holes, the better the cloaking performance. In addition, the nanoscale thermal cloak still exhibits good cloaking performance in the dynamic environment. Finally, the cloaking mechanism is analyzed by calculating the phonon density of states (PDOS) and mode participation rate (MPR), and the reduction of thermal conductivity in the functional region is attributed to phonon localization.

Design, analysis, and test of a decoupled flexure-based 5-DOF micro-positioning platform

Jian Zhang,Yujia Zhang,Minglun Dong 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.8

This paper presents the mechanical design, simulation analysis and experimentation of a decoupled 5-degree-of-freedom (5-DOF) micro-positioning platform, which is composed of a 2-DOF micro-displacement platform, a 1-DOF micro-displacement platform and a 2-DOF micro-rotation platform in series. Double four-bar parallelogram structure and a new 2-DOF rotary guiding mechanism based on flexure hinges are applied to realize motion decoupling, and the displacement of the piezoelectric actuator is amplified with a bridge mechanism. The static models of the micro-displacement platform and micro-rotation platform are established by the compliance matrix method. Then the dynamic models of the two sub-platforms are established to obtain their natural frequencies. The performance of the 5-DOF platform is evaluated through finite element analysis and experiment test. It turns out that the theoretical model and simulation model established in this paper have high accuracy, the platform also performs well in motion decoupling, motion stroke and natural frequency.

Crystal Structure, Fluorescence Property and Theoretical Calculation of the Zn(II) Complex with o-Aminobenzoic Acid and 1,10-Phenanthroline

Zhang, Zhongyu,Bi, Caifeng,Fan, Yuhua,Zhang, Xia,Zhang, Nan,Yan, Xingchen,Zuo, Jian Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.6

A novel complex [$Zn(phen)(o-AB)_2$] [phen: 1,10-phenanthroline o-AB: o-aminobenzoic acid] was synthesized and characterized by elemental analysis and X-ray diffraction single-crystal analysis. The crystal crystallizes in monoclinic, space group P2(1)/c with $a=7.6397(6){\AA}$, $b=16.8761(18){\AA}$, $c=17.7713(19){\AA}$, ${\alpha}=90^{\circ}$, ${\beta}=98.9570(10)^{\circ}$, ${\gamma}=90^{\circ}$, $V=2.2633(4)nm^3$, Z = 4, F(000) = 1064, S = 1.058, $Dc=1.520g{\cdot}cm^{-3}$, $R_1=0.0412$, $wR_2=0.0948$, ${\mu}=1.128mm^{-1}$. The Zn(II) is six coordinated by two nitrogen and four oxygen atoms from the 1,10-phenanthroline and o-aminobenzoic acid to furnish a distorted octahedron geometry. The complex exhibits intense fluorescence at room temperature. Theoretical studies of the title complex were carried out by density functional theory (DFT) B3LYP method. CCDC: 898291.

Grouting effects evaluation of water-rich faults and its engineering application in Qingdao Jiaozhou Bay Subsea Tunnel, China

Zhang, Jian,Li, Shucai,Li, Liping,Zhang, Qianqing,Xu, Zhenhao,Wu, Jing,He, Peng Techno-Press 2017 Geomechanics & engineering Vol.12 No.1

In order to evaluate the grouting effects of water-rich fault in tunnels systematically, a feasible and scientific method is introduced based on the extension theory. First, eight main influencing factors are chosen as evaluation indexes by analyzing the changes of permeability, mechanical properties and deformation of surrounding rocks. The model of evaluating grouting effects based on the extension theory is established following this. According to four quality grades of grouting effects, normalization of evaluation indexes is carried out, aiming to meet the requirement of extension theory on data format. The index weight is allocated by adopting the entropy method. Finally, the model is applied to the grouting effects evaluation in water-rich fault F4-4 of Qingdao Jiaozhou Bay Subsea Tunnel, China. The evaluation results are in good agreement with the test results on the site, which shows that the evaluation model is feasible in this field, providing a powerful tool for systematically evaluating the grouting effects of water-rich fault in tunnels.

Preparation and Adsorption Properties of PA6/PSMA-OA Molecularly Imprinted Composite Membranes in Supercritical CO₂

Zhang, Qing,Zhang, Xingyuan,Zhang, Wencheng,Pan, Jian,Liu, Ling,Zhang, Haitao,Zhao, Dong,Li, Zhi Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.9

Oleanolic acid (OA) as template molecule, polyamide-6 (PA6) as basement membrane and poly(styrene-comaleic acid) (PSMA) were used to prepare PA6/PSMA-OA molecularly imprinted composite membranes by phase inversion method in supercritical $CO_2$ ($ScCO_2$). The template molecule (OA), [poly(styrene-co-maleic anhydride) (PSMAH), PSMA, molecularly imprinted membranes (MIMs) imprinting OA and MIMs after elution were all characterized by Fourier transform infrared spectroscopy (FTIR). The conditions that were the mass ratio between PSMA and OA from 3:1 to 8:1, temperature of $ScCO_2$ from $35^{\circ}C$ to $50^{\circ}C$ and pressure of $ScCO_2$ 12 MPa to 17 MPa were studied. It was obtained the largest adsorption rate and purity of OA after adsorption of the resultant MIMs, 50.41% and 96.15% respectively. After using PA6 film and non-woven fabrics as basement membrane respectively, it was found that smaller aperture of PA6 was used as basement membrane, a higher adsorption rate and a higher purity of OA after adsorption of the MIMs were obtained, and so were the stability and reproducibility of the resultant MIMs. After template molecules being removed, the MIMs had effective selectivity hydrogen bonding to separately bind in the binary components to the template molecules-oleanolic acid.

Carbon dispersed iron-manganese catalyst for light olefin synthesis from CO hydrogenation

Jianli Zhang,Kegong Fang,Kan Zhang,Wenhuai Li,Yuhan Sun 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.3

High performance iron-manganese catalysts dispersed with carbon to produce light olefins from CO hydrogenation were prepared by sol-gel method using citric acid as precursor. The effects of carbon content on the bulk structure, the water gas shift reaction, the chain propagation ability and the activity and selectivity of the catalysts were investigated. The results showed that the catalysts were gradually reduced during the decomposition of the precursor when calcined under pure N2. The formation of iron-manganese mixed crystallites was favored and stabilized because of the enhanced interaction of iron and manganese with increasing carbon content. During the subsequent CO hydrogenation reaction, all the catalysts showed high activity and olefin selectivity. With increasing carbon content, the water gas shift (WGS) reaction was restrained and the chain propagation ability was inhibited. Catalysts with higher carbon content showed much lighter hydrocarbon products; however, the selectivity of CH4 was almost unchanged.