scholarly journals Joint Range-Doppler-Angle Estimation for OFDM-Based RadCom System via Tensor Decomposition

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Bo Kong ◽  
Yuhao Wang ◽  
Xiaohua Deng ◽  
Dong Qin
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Decomposition Method ◽  
Tensor Decomposition ◽  
High Energy ◽  
Local Extremum ◽  
Joint Estimation ◽  
Superior Performance ◽  
Green Communications ◽  
Tensor Power ◽  
Doppler Angle

Radar and communication (RadCom) systems have received increasing attention due to their high energy efficiency and spectral efficiency. They have been identified as green communications. This paper is concerned with a joint estimation of range-Doppler-angle parameters for an orthogonal frequency division multiplexing (OFDM) based RadCom system. The key idea of the proposed method is to derive different factor matrices by the tensor decomposition method and then extract parameters of the targets from these factor matrices. Different from the classical tensor decomposition method via alternating least squares or higher-order singular value decomposition, we adopt a greedy based method with each step constituted by a rank-1 approximation subproblem. To avoid local extremum, the rank-1 approximation is solved by using a multiple random initialized tensor power method with a comparison procedure followed. A parameterized rectification method is also proposed to incorporate the inherent structures of the factor matrices. The proposed algorithm can estimate all the parameters simultaneously without parameter pairing requirement. The numerical experiments demonstrate superior performance of the proposed algorithm compared with the existing methods.

In situ TEM Studies of agglomeration of sub-nanometer Ru layers in Ru/C multilayers

1992 ◽  
Vol 50 (1) ◽  
pp. 256-257
Author(s):  
Tai D. Nguyen ◽  
Ronald Gronsky ◽  
Jeffrey B. Kortright
Keyword(s):  
Layered Structure ◽  
Driving Force ◽  
High Energy ◽  
Superior Performance ◽  
In Situ Tem ◽  
Rayleigh Instability ◽  
Practical Applications ◽  
Transmission Electron ◽  
Diffraction Patterns

Nanometer period Ru/C multilayers are one of the prime candidates for normal incident reflecting mirrors at wavelengths < 10 nm. Superior performance, which requires uniform layers and smooth interfaces, and high stability of the layered structure under thermal loadings are some of the demands in practical applications. Previous studies however show that the Ru layers in the 2 nm period Ru/C multilayer agglomerate upon moderate annealing, and the layered structure is no longer retained. This agglomeration and crystallization of the Ru layers upon annealing to form almost spherical crystallites is a result of the reduction of surface or interfacial energy from die amorphous high energy non-equilibrium state of the as-prepared sample dirough diffusive arrangements of the atoms. Proposed models for mechanism of thin film agglomeration include one analogous to Rayleigh instability, and grain boundary grooving in polycrystalline films. These models however are not necessarily appropriate to explain for the agglomeration in the sub-nanometer amorphous Ru layers in Ru/C multilayers. The Ru-C phase diagram shows a wide miscible gap, which indicates the preference of phase separation between these two materials and provides an additional driving force for agglomeration. In this paper, we study the evolution of the microstructures and layered structure via in-situ Transmission Electron Microscopy (TEM), and attempt to determine the order of occurence of agglomeration and crystallization in the Ru layers by observing the diffraction patterns.

scholarly journals Celery-derived porous carbon materials for superior performance supercapacitor

2021 ◽  
Author(s):  
Sirui Liu ◽  
Ya ping Xu ◽  
Jinggao Wu ◽  
Jing Huang
Keyword(s):  
Porous Carbon ◽  
Carbon Materials ◽  
High Energy ◽  
Cycle Life ◽  
Superior Performance ◽  
Energy Output ◽  
Next Generation ◽  
Porous Carbon Materials ◽  
Long Cycle Life ◽  
Sustainable Materials

Supercapacitors are of paramount importance for next-generation applications, demonstrating high energy output, an ultra-long cycle life and utilizing green and sustainable materials. Herein, we utilize celery, a common biomass from...

scholarly journals Oxygen-Deficient β-MnO2@Graphene Oxide Cathode for High-Rate and Long-Life Aqueous Zinc Ion Batteries

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Shouxiang Ding ◽  
Mingzheng Zhang ◽  
Runzhi Qin ◽  
Jianjun Fang ◽  
Hengyu Ren ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Manganese Oxides ◽  
Rate Capability ◽  
High Energy ◽  
Zinc Ion ◽  
Cycling Stability ◽  
High Rate ◽  
High Energy Density ◽  
Superior Performance ◽  
Long Life

AbstractRecent years have witnessed a booming interest in grid-scale electrochemical energy storage, where much attention has been paid to the aqueous zinc ion batteries (AZIBs). Among various cathode materials for AZIBs, manganese oxides have risen to prominence due to their high energy density and low cost. However, sluggish reaction kinetics and poor cycling stability dictate against their practical application. Herein, we demonstrate the combined use of defect engineering and interfacial optimization that can simultaneously promote rate capability and cycling stability of MnO2 cathodes. β-MnO2 with abundant oxygen vacancies (VO) and graphene oxide (GO) wrapping is synthesized, in which VO in the bulk accelerate the charge/discharge kinetics while GO on the surfaces inhibits the Mn dissolution. This electrode shows a sustained reversible capacity of ~ 129.6 mAh g−1 even after 2000 cycles at a current rate of 4C, outperforming the state-of-the-art MnO2-based cathodes. The superior performance can be rationalized by the direct interaction between surface VO and the GO coating layer, as well as the regulation of structural evolution of β-MnO2 during cycling. The combinatorial design scheme in this work offers a practical pathway for obtaining high-rate and long-life cathodes for AZIBs.

scholarly journals Fast Estimation Method of Space-Time Two-Dimensional Positioning Parameters Based on Hadamard Product

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Haiwen Li ◽  
Nae Zheng ◽  
Xiyu Song ◽  
Yinghua Tian
Keyword(s):  
Frequency Domain ◽  
Orthogonal Frequency Division Multiplexing ◽  
Hadamard Product ◽  
Estimation Method ◽  
Space Time ◽  
Joint Estimation ◽  
Two Dimensional ◽  
Music Algorithm ◽  
Fast Estimation ◽  
Response Vector

The estimation speed of positioning parameters determines the effectiveness of the positioning system. The time of arrival (TOA) and direction of arrival (DOA) parameters can be estimated by the space-time two-dimensional multiple signal classification (2D-MUSIC) algorithm for array antenna. However, this algorithm needs much time to complete the two-dimensional pseudo spectral peak search, which makes it difficult to apply in practice. Aiming at solving this problem, a fast estimation method of space-time two-dimensional positioning parameters based on Hadamard product is proposed in orthogonal frequency division multiplexing (OFDM) system, and the Cramer-Rao bound (CRB) is also presented. Firstly, according to the channel frequency domain response vector of each array, the channel frequency domain estimation vector is constructed using the Hadamard product form containing location information. Then, the autocorrelation matrix of the channel response vector for the extended array element in frequency domain and the noise subspace are calculated successively. Finally, by combining the closed-form solution and parameter pairing, the fast joint estimation for time delay and arrival direction is accomplished. The theoretical analysis and simulation results show that the proposed algorithm can significantly reduce the computational complexity and guarantee that the estimation accuracy is not only better than estimating signal parameters via rotational invariance techniques (ESPRIT) algorithm and 2D matrix pencil (MP) algorithm but also close to 2D-MUSIC algorithm. Moreover, the proposed algorithm also has certain adaptability to multipath environment and effectively improves the ability of fast acquisition of location parameters.

scholarly journals Rational synthesis of silicon into polyimide-derived hollow electrospun carbon nanofibers for enhanced lithium storage

e-Polymers ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 491-499 ◽  
Author(s):  
Fan Wang ◽  
Shouzhi Zhang ◽  
Jiawei Zhang ◽  
Manshu Han ◽  
Guoxiang Pan ◽  
...  
Keyword(s):  
Shell Structure ◽  
Carbon Nanofiber ◽  
Lithium Ion ◽  
High Energy ◽  
High Energy Density ◽  
Superior Performance ◽  
Core Shell ◽  
Discharge Process ◽  
Energy Devices ◽  
Core Shell Structure

AbstractFlexible energy devices with high energy density and long cycle life are considered to be promising applications in portable electronics. In this study, silicon/carbon nanofiber (Si@CNF) core–shell electrode has been prepared by the coaxial electrospinning method. The precursors of polyimide (PI) were for the first time used to form the core–shell structure of Si@CNF, which depicts outstanding flexibility and mechanical strength. The effect of doping concentrations of silicon (Si) nanoparticles embedded in the fiber is investigated as a binder-free anode for lithium-ion batteries. A 15 wt% doped composite electrode demonstrates superior performance, with an initial reversible capacity of 621 mA h g−1 at the current density of 100 mA g−1 and a high capacity retention up to 200 cycles. The excellent cycling performance is mainly due to the carbonized PI core–shell structure, which not only can compensate for the insulation property of Si but also has the ability to buffer the volume expansion during the repeated charge–discharge process.

Single crystal Ni-rich layered cathodes enabling superior performance in all-solid-state batteries with PEO-based solid electrolytes

2021 ◽  
Author(s):  
Maoyi Yi ◽  
Li Jie ◽  
Xin-ming Fan ◽  
Maohui Bai ◽  
Zhi Zhang ◽  
...  
Keyword(s):  
Solid State ◽  
Energy Density ◽  
Single Crystal ◽  
Solid Electrolytes ◽  
High Energy ◽  
High Energy Density ◽  
Superior Performance ◽  
Composite Electrolytes ◽  
Solid State Batteries ◽  
All Solid State Batteries

PEO-based composite electrolytes are one of the most practical electrolytes in all-solid batteries (ASSBs). To achieve the perspective of ASSBs with high energy density, PEO based composite electrolytes should match...

scholarly journals Effective Blind Frequency Offset Estimation Scheme for BST-OFDM Based HDTV Broadcast Systems

Symmetry ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 379 ◽  
Author(s):  
Yong-An Jung ◽  
Young-Hwan You
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Carrier Frequency Offset ◽  
Frequency Offset ◽  
Joint Estimation ◽  
Pilot Symbols ◽  
Quality Video ◽  
Estimation Scheme ◽  
Digital Broadcasting ◽  
High Quality Video ◽  
T System

The integrated services digital broadcasting-terrestrial (ISDB-T) system is designed in order to accommodate high-quality video/audio and multimedia services, using band segmented transmission orthogonal frequency division multiplexing (BST-OFDM) scheme. In the ISDB-T system, the pilot configuration varies depending on whether a segment uses a coherent or differential modulation. Therefore, it is necessary to perform a joint estimation of carrier frequency offset (CFO) and sampling frequency offset (SFO) independent of the segment format in the ISDB-T system. The goal is to complete those synchronization tasks while considering an information-carrying transmission and multiplexing configuration control (TMCC) signal as pilot symbols. It is demonstrated through numerical simulations that the differential BPSK-modulated TMCC information can be efficiently used for a least-squares estimation of CFO and SFO, offering an acceptable performance.

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