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Zhenguo Gao

Bio: Zhenguo Gao is an academic researcher from Tianjin University. The author has contributed to research in topics: Network packet & Crystallization. The author has an hindex of 19, co-authored 149 publications receiving 1585 citations. Previous affiliations of Zhenguo Gao include Harbin Institute of Technology & Dalian University of Technology.


Papers
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Journal ArticleDOI
TL;DR: In this paper, ZnFe2O4 quantum dots were coated by hybrid amorphous carbon to form a sea islands structure by a facile electrostatic self-assembly synthetic technology.
Abstract: Making effective usage of quantum size effect is a foregrounded strategy to design and fabricate excellent electromagnetic microwave absorption materials. In this research, ZnFe2O4 quantum dots were coated by hybrid amorphous carbon to form a sea islands structure by a facile electrostatic self-assembly synthetic technology. Simultaneously, the rejection of heterogeneous charges leads to the formation of quantum dots, by which the quantum size effects on dielectric and magnetic characteristic were investigated. Consequently, multiple hetero-interface and interfacial polarization was originated from polycrystalline feature of ZnFe2O4 with spinel and inverse spinel structures. In particular, the electromagnetic microwave absorption properties of ZnFe2O4 were greatly optimized, as the minimized reflection loss reached −40.68 dB at the frequency 11.44 GHz and thickness 2.5 mm, while the effective bandwidth corresponding was 3.66 GHz (from 9.87 to 13.52 GHz). The largest effective bandwidth was 4.16 GHz (from 8.08 to 12.24 GHz) with a thickness of 3 mm. It is suggested that high performance of microwave absorption of ZnFe2O4 quantum dots was well guided by the optimized impedance matching and attenuation constants.

171 citations

Journal ArticleDOI
TL;DR: In this article, two kinds of lead-free relaxor-ferroelectric BNT-based ceramic hierarchical polycrystalline alloys (La3Ni2O7/LaNiO3, La2NiO4/La2O3) were prepared via a facile solvothermal and high-temperature annealing technique as high-performance EMW absorption materials (MAMs).

139 citations

Journal ArticleDOI
TL;DR: A review of recent developments in crystal engineering and crystallization process design and control in the pharmaceutical industry can be found in this article, where the authors systematically summarize recent methods for understanding and developing new types of crystals such as co-crystals, polymorphs, and solvates, and include several milestones such as the launch of the first cocrystal drug Entresto (Novartis), and the continuous manufacture of Orkambi (Vertex).

134 citations

Journal ArticleDOI
01 Feb 2016
TL;DR: Weighting depth and forwarding area division DBR routing protocol, called WDFAD-DBR, which considers not only the current depth but also the depth of expected next hop to reduce the probability of encountering void holes in the sparse networks.
Abstract: The design of routing protocols for Underwater Acoustic Sensor Networks (UASNs) poses many challenges due to long propagation, high mobility, limited bandwidth, multi-path and Doppler effect. Because of the void-hole caused by the uneven distribution of nodes and sparse deployment, the selection of next hop forwarding nodes only based on the state of current node may result in the failure of forwarding in the local sparse region. In order to reduce the probability of encountering void holes in the sparse networks, in this paper we present weighting depth and forwarding area division DBR routing protocol, called WDFAD-DBR. The novelties of WDFAD-DBR lie in: firstly, next forwarding nodes are selected according to the weighting sum of depth difference of two hops, which considers not only the current depth but also the depth of expected next hop. In this way, the probability of meeting void holes is effectively reduced. Secondly, the mechanisms for forwarding area division and neighbor node prediction are designed to reduce the energy consumption caused by duplicated packets and neighbors' requests, respectively. Thirdly, we make theoretical analyses on routing performance in case of considering channel contending with respect to delivery ratio, energy consumption and average end-to-end delay. Finally we conduct extensive simulations using NS-3 simulator to verify the effectiveness and validity of WDFAD-DBR.

121 citations

Journal ArticleDOI
TL;DR: In this paper, Laminated hybrid carbon of amorphous carbon and reduced graphene oxide perovskite composite, La0.8FeO3/C/RGO-BD, was fabricated by a simple method in one pot.
Abstract: Laminated hybrid carbon of amorphous carbon and RGO (reduced graphene oxide) perovskite composite, La0.8FeO3/C/RGO-BD, was fabricated by a simple method in one pot. The amorphous carbon was carbonized from d -glucose which also played a role as reducing agent. RGO provided a great condition for the formation of conductive loops. While A-site cation deficiency perovskite La0.8FeO3 doped at carbon nanosheets was induced to adjust the comprehensive microwave absorption properties. The phase and composition characteristics were studied by X-ray diffraction patterns (XRD), Raman and FT-IR spectrums and X-ray photoelectron spectroscopy (XPS), especially the confirmation of the existence of A-site cation deficiency and Oxygen vacancy. The morphology and microstructure of samples were visualized by a scanning electron microscope (SEM) and a transmission electron microscope (TEM). The electromagnetic microwave absorption properties were further studied, as the reflection loss of La0.8FeO3/C/RGO-BD reached −42.69 dB at 8.08 GHz with an effective band 2.72 GHz at 3.15 mm. And the excellent microwave absorption properties were confirmed by impedance matching, one quarter-wavelength theory, Debye relaxation polarization theory and eddy current loss.

114 citations


Cited by
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01 Feb 1995
TL;DR: In this paper, the unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio using DFT, MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set.
Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

1,652 citations

01 Jan 2016
TL;DR: This rfid handbook fundamentals and applications in contactless smart cards and identification helps people to read a good book with a cup of coffee in the afternoon instead of juggled with some malicious bugs inside their laptop.
Abstract: Thank you for reading rfid handbook fundamentals and applications in contactless smart cards and identification. As you may know, people have search numerous times for their chosen novels like this rfid handbook fundamentals and applications in contactless smart cards and identification, but end up in malicious downloads. Rather than reading a good book with a cup of coffee in the afternoon, instead they juggled with some malicious bugs inside their laptop.

570 citations

Journal ArticleDOI
TL;DR: The learning problem in cognitive radios (CRs) is characterized and the importance of artificial intelligence in achieving real cognitive communications systems is stated and the conditions under which each of the techniques may be applied are identified.
Abstract: In this survey paper, we characterize the learning problem in cognitive radios (CRs) and state the importance of artificial intelligence in achieving real cognitive communications systems. We review various learning problems that have been studied in the context of CRs classifying them under two main categories: Decision-making and feature classification. Decision-making is responsible for determining policies and decision rules for CRs while feature classification permits identifying and classifying different observation models. The learning algorithms encountered are categorized as either supervised or unsupervised algorithms. We describe in detail several challenging learning issues that arise in cognitive radio networks (CRNs), in particular in non-Markovian environments and decentralized networks, and present possible solution methods to address them. We discuss similarities and differences among the presented algorithms and identify the conditions under which each of the techniques may be applied.

455 citations

Journal ArticleDOI
TL;DR: Process, micro- and macrostructure, and magneto-mechanical properties of Ni-Mn-Ga powders, fibers, ribbons and films with one or more small dimension are reviewed, which are amenable to the growth of bamboo grains leading to large MFIS, and "constructs" from these structural elements are proposed.
Abstract: The off-stoichiometric Ni2MnGa Heusler alloy is a magnetic shape-memory alloy capable of reversible magnetic-field-induced strains (MFIS). These are generated by twin boundaries moving under the influence of an internal stress produced by a magnetic field through the magnetocrystalline anisotropy. While MFIS are very large (up to 10%) for monocrystalline Ni-Mn-Ga, they are near zero (<0.01%) in fine-grained polycrystals due to incompatibilities during twinning of neighboring grains and the resulting internal geometrical constraints. By growing the grains and/or shrinking the sample, the grain size becomes comparable to one or more characteristic sample sizes (film thickness, wire or strut diameter, ribbon width, particle diameter, etc), and the grains become surrounded by free space. This reduces the incompatibilities between neighboring grains and can favor twinning and thus increase the MFIS. This approach was validated recently with very large MFIS (0.2-8%) measured in Ni-Mn-Ga fibers and foams with bamboo grains with dimensions similar to the fiber or strut diameters and in thin plates where grain diameters are comparable to plate thickness. Here, we review processing, micro- and macrostructure, and magneto-mechanical properties of (i) Ni-Mn-Ga powders, fibers, ribbons and films with one or more small dimension, which are amenable to the growth of bamboo grains leading to large MFIS, and (ii) “constructs” from these structural elements (e.g., mats, laminates, textiles, foams and composites). Various strategies are proposed to accentuate this geometric effect which enables large MFIS in polycrystalline Ni-Mn-Ga by matching grain and sample sizes.

307 citations

Journal ArticleDOI
01 Nov 2019-Carbon
TL;DR: In this article, a co-doped carbon foam was fabricated via a facile hydrothermal and subsequent pyrolysis process using fish skin as carbon precursor, and the unique architecture endows the 3D carbon foam with impressive microwave absorbing property.

302 citations