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Dot-shaped beamforming analysis of subarray-based sin-FDA Research Article

Bo Wang, Jun-wei Xie, Jing Zhang, Jia-ang Ge,wb_wangbo1991@163.com

Frontiers of Information Technology & Electronic Engineering 2019, Volume 20, Issue 10, Pages 1429-1444 doi: 10.1631/FITEE.1800722

Abstract: Phased array (PA) radar is one of the most popular types of radar. In contrast to PA, the (FDA) is a potential solution to suppress range-related interference because of its time-range-angle-dependent beampattern. However, the range-angle coupling inherent in the FDA transmit beampattern may degrade the output signal-to-interference-plus-noise ratio (SINR). We propose a method based on the analyzed four subarray-based FDAs and subarray-based planar FDAs using a sinusoidally increasing frequency offset with elements transmitting at multiple frequencies. The numerical results show that the proposed approach outperforms the existing log-FDA with logarithmical frequency offset in transmit energy focus, sidelobe suppression, and array resolution. Comparative simulation results validate the effectiveness of the proposed method.

Keywords：频率分集阵列；子阵频率分集阵列；解耦；点状波束形成

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Deceptive jamming discrimination based on range-anglelocalization of a frequency diverse array Article

Zhao-jian ZHANG, Jun-wei XIE, Chuan SHENG, Zhun TANG

Frontiers of Information Technology & Electronic Engineering 2017, Volume 18, Issue 9, Pages 1437-1446 doi: 10.1631/FITEE.1601577

Abstract: We propose a method to suppress deceptive jamming by frequencydiverse array (FDA) in radar electronic countermeasure environments.FDA offers a new range-angle-dependent beam pattern through a smallfrequency increment across elements. Due to the coupling between theangle and range, a mismatch between the test angle and physical angleoccurs when the slant range on which the beam focuses is not equalto the slant range of the real target. In addition, the range of thetarget can be extracted by sum-difference beam except for time-delaytesting, because the beam provides a range resolution in the FDA thatcannot be deceived by traditional deceptive jamming. A strategy ofusing FDA to transmit two pulses with zero and nonzero frequency increments,respectively, is proposed to ensure that the angle of a target canbe obtained by FDA. Moreover, the localization performance is examinedby analyzing the Cramer-Rao lower bound and detection probability.Effectiveness of the proposed method is confirmed by simulation results.

Keywords： Frequency diverse array (FDA) Deceptive jamming Range-angle coupling Sum-difference beam Double-pulse

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A novel wideband ring antenna for polarization/pattern diversity Correspondence

Li SUN, Shigang ZHOU, Guanxi ZHANG, Baohua SUN

Frontiers of Information Technology & Electronic Engineering 2022, Volume 23, Issue 6, Pages 975-983 doi: 10.1631/FITEE.2100421

Abstract:

We present a novel wideband ring antenna for polarization/pattern diversity. The proposed antenna consists of eight printed dipole elements in the form of a circular array. The arms of adjacent elements overlap for capacitive loading. Unlike traditional circular arrays, a method of exciting elements in the form of every two intervals is first introduced. We prove that this method can maintain the wideband characteristics of the antenna. Four independent feeding ports in a ring antenna aperture are designed for the polarization/pattern diversity with suitable feeding networks. As an example, a wideband dual-polarized antenna was designed based on the proposed ring antenna. To achieve two orthogonal linear polarizations with maximum radiation in the direction, two adjacent elements are extracted periodically to feed through one port. The differential feeding network and integrated Baluns have been designed to realize broadside radiation patterns, considering impedance and phase matching. Because the proposed antenna is hollow, it is a good candidate for a multiband sharing aperture antenna element. Results show that the proposed antenna has an overlapped bandwidth of 50.5% (1.04–1.82 GHz) with voltage standing wave ratio (VSWR)<2 for the two polarizations, and port isolation less than 23 dB. The measured realized gain ranges from 6.1 to 8.1 dBi, with stable broadside radiation patterns over the operating frequency band.

Keywords：环形天线；宽带天线；极化分集；方向图分集

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利用对称结构和结合差分进化的文化算法检测阵列中的故障传感器 Article

Shafqat Ullah KHAN,Ijaz Mansoor QURESHI,Fawad ZAMAN,Wasim KHAN

Frontiers of Information Technology & Electronic Engineering 2017, Volume 18, Issue 2, Pages 235-245 doi: 10.1631/FITEE.1500315

Abstract: 本文解决了从N个传感器组成的线性阵列中检测完全或部分缺陷传感器的问题。本文首先提出了一种线性阵列的对称结构，其次，基于结合差分进化的文化算法，建立了一种混合技术。

Keywords：文化算法；差分进化；线性对称传感器阵列

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Omnidirectional Antenna Diversity System for High-Speed Onboard Communication Article

Yongjian Zhang, Yue Li, Weiquan Zhang, Zhijun Zhang, Zhenghe Feng

Engineering 2022, Volume 11, Issue 4, Pages 72-79 doi: 10.1016/j.eng.2020.10.014

Abstract:

In this article, an omnidirectional dual-polarized antenna with synergetic electromagnetic and aerodynamic properties is propounded for high-speed diversity systems. The propounded antenna comprises a probe-fed cavity for horizontally polarized radiation and a microstrip-fed slot for vertical polarization. Double-layer metasurfaces are properly designed as artificial magnetic conductor boundaries with direct metal-mountable onboard installation and compact sizes. An attached wedge-shaped block is utilized for windage reduction in hydrodynamics. The propounded antenna is fabricated for design verification, and the experimental results agree well with the simulated ones. For vertical polarization, the operating bandwidth is in the range of 2.37–2.55 GHz, and the realized gain variation in the azimuthal radiation pattern is 3.67 decibels (dB). While an impedance bandwidth in the range of 2.45–2.47 GHz and a gain variation of 3.71 dB are also achieved for horizontal polarization. A port isolation more than 33 dB is obtained in a compact volume of 0.247λ₀ × 0.345λ₀ × 0.074λ₀, where λ₀ represents the wavelength in vacuum at the center frequency, wherein the wedge-shaped block is included. The propounded diversity antenna has electromagnetic and aerodynamic merits, and exhibits an excellent potential for high-speed onboard communication.

Keywords： Antenna diversity system Aerodynamics Electromagnetics Omnidirectional radiation High-speed onboard communication

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Calculation and research on deepwater drilling riser flexural equation and natural frequency

Jiang Wei

Strategic Study of CAE 2011, Volume 13, Issue 5, Pages 66-73

Abstract:

Flexural equation was established in this paper, which was based on application of deepwater drilling riser and Ritz methods in elastoplastic mechanics. Axial tension, inclination angle, lateral gravity components and axial gravity components were considered. Therefore, simple calculation method for natural frequency of drilling riser was achieved. Free-hinged beam was taken as constraint condition of flexural equation combined with drilling string real conditions, which made research approach practical work more. Purpose of research was to provide reasonable design and selection for deepwater drilling riser, and provide a more efficient and applied method, which would show guiding significance for deepwater drilling operation.

Keywords： deepwater drilling drilling riser flexural equation natural frequency shape function

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The Optimization of the Monopulse Antenna Based on Genetic Algorithms

Wang Hongjian,Gao Benqing,Liu Ruixiang

Strategic Study of CAE 2002, Volume 4, Issue 5, Pages 84-87

Abstract:

The sum and difference patterns as well as the directivity of the monopulse antenna arrays are optimized based on genetic algorithms (GA). When only the sum pattern is optimized as usual, the difference pattern and gain can not be guaranteed, so the track precision and effective distance of the antenna or missile will be impaired. However, using GA, the sum pattern, difference pattern and directivity can be optimized thoroughly for the antenna design.

Keywords： monopulse antenna array genetic algorithm pattern directivity

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A Polarization Programmable Antenna Array Article

Dingzhao Chen, Yanhui Liu, Ming Li, Pan Guo, Zhuo Zeng, Jun Hu, Y. Jay Guo

Engineering 2022, Volume 16, Issue 9, Pages 100-114 doi: 10.1016/j.eng.2022.03.015

Abstract:

Reconfigurable antennas are becoming a major antenna technology for future wireless communications and sensing systems. It is known that, with a single linear polarization (LP) reconfigurable antenna element, a preferred polarization can be produced from a set of multiple polarization states, thus improving the quality of the communication link. This paper presents a new concept of a polarization programmable reconfigurable antenna array that consists of a number of polarization reconfigurable antenna elements with a finite number of possible polarization states. By employing a new optimization strategy and programming the polarization states of all the array elements, we demonstrate that it is possible to realize any desired LP in the vectorial array radiation pattern with accurate control of sidelobe and crosspolarization levels (XPLs), thereby achieving the desired polarization to perfectly match that of the required communications signal. Both numerical and experimental results are provided to prove the concept, and they agree well with each other.

Keywords：阵列天线极化可编程天线可重构天线

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Microwave－Optical Frequency Standards at NIM：Realizing of Definition of Metre and Second

Li Tianchun

Strategic Study of CAE 2007, Volume 9, Issue 6, Pages 27-31

Abstract:

The paper presents the realization, at NIM, of SI time unit second using the NIM4 cesium fountain clock, SI length unit meter using a femto-second (FS) optical frequency comb and calibration of wavelengths of stabilized lasers by this FS comb. The uncertainty of NIM4 fountain clock was evaluated as 5 × 10 ^{- 15}. The frequency uncertainty of the FS optical comb locked to a H-maser, which is steered by NIM4 clock, was estimated as 2. 2 × 10^{- 14}. The function, significance of Cs fountain clock, stabilized lasers, optical comb and relationship among them are discussed. Finally the progress of NIM5 fountain clock and the construction of a Sr atom optical clock started in 2006 at NIM are reported.

Keywords： metrology frequency standard stabilized laser Cs fountain clock FS optical comb

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Research on Prony’s method modeling in multi-target detection of stepped-frequency radar

Hu Tiling,Li Xingguo

Strategic Study of CAE 2008, Volume 10, Issue 10, Pages 67-71

Abstract:

Stepped-frequency signal is a broad band signal which enhances range resolution of radar at the cost of increasing bandwidth. Baseband signal that is received in stepped-frequency radar can be thought of as the linear combination of exponential function which contains target information, while Prony algorithm is a mathematical mode which uses a linear combination of exponential function to describe equal space between sampling data. Extended Prony algorithm is applied to stepped-frequency radar, which can obtain more exact target information and overcome the shortcomings of using IDFT to synthesize high resolution range profiles. Corresponding modeling analysis and experiment simulation explain the advantages of Prony's method.

Keywords： high resolution radar stepped-frequency signal extended Prony’s method multi-scattering center

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Decoupling methods of MIMO antenna arrays for 5G applications: a review Review Articles

Xiao-xi ZHANG, Ai-di REN, Ying LIU

Frontiers of Information Technology & Electronic Engineering 2020, Volume 21, Issue 1, Pages 62-71 doi: 10.1631/FITEE.1900466

Abstract: Multiple-input multiple-output (MIMO) technique is a key technique for communication in the future. It can effectively enhance channel capacity. For future fifth-generation (5G) terminals, it is still a challenging task to realize desirable isolation within a compact size. To achieve an acceptable isolation level, many decoupling methods have been developed. We review the most recent research on decoupling methods, including the employment of external decoupling structures, orthogonal modes, and reduction of ground effect, and discuss the development trends of the MIMO array in 5G smartphones.

Keywords： MIMO array 5G smartphone Decoupling methods

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Dynamic power-gating for leakage power reduction in FPGAs Research Article

Hadi JAHANIRAD,h.jahanirad@uok.ac.ir

Frontiers of Information Technology & Electronic Engineering 2023, Volume 24, Issue 4, Pages 582-598 doi: 10.1631/FITEE.2200084

Abstract: devices have become widespread in electronic systems due to their low design costs and reconfigurability. In battery-restricted applications such as handheld electronics systems, low-power FPGAs are in great demand. almost equals dynamic power in modern integrated circuit technologies, so the reduction of leads to significant energy savings. We propose a power-efficient architecture for static random access memory (SRAM) based FPGAs, in which two modes (active mode and sleep mode) are defined for each module. In sleep mode, ultra-low is consumed by the module. The module mode changes dynamically from sleep mode to active mode when module outputs evaluate for new input vectors. After producing the correct outputs, the module returns to sleep mode. The proposed circuit design reduces the consumption in both active and sleep modes. The proposed low-leakage FPGA architecture is compared with state-of-the-art architectures by implementing Microelectronics Center of North Carolina (MCNC) benchmark circuits on FPGA-SPICE software. Simulation results show an approximately 95% reduction in consumption in sleep mode. Moreover, the total power consumption (leakage+dynamic power consumption) is reduced by more than 15% compared with that of the best previous design. The average area overhead (4.26%) is less than those of other designs.

Keywords： Field programmable gate array (FPGA) Leakage power Power-gating Transistor-level circuit design

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FrepJoin: an efficient partition-based algorithm for edit similarity join Article

Ji-zhou LUO, Sheng-fei SHI, Hong-zhi WANG, Jian-zhong LI

Frontiers of Information Technology & Electronic Engineering 2017, Volume 18, Issue 10, Pages 1499-1510 doi: 10.1631/FITEE.1601347

Abstract: String similarity join (SSJ) is essential for many applications where near-duplicate objects need to be found. This paper targets SSJ with edit distance constraints. The existing algorithms usually adopt the filter-andrefine framework. They cannot catch the dissimilarity between string subsets, and do not fully exploit the statistics such as the frequencies of characters. We investigate to develop a partition-based algorithm by using such statistics. The frequency vectors are used to partition datasets into data chunks with dissimilarity between them being caught easily. A novel algorithm is designed to accelerate SSJ via the partitioned data. A new filter is proposed to leverage the statistics to avoid computing edit distances for a noticeable proportion of candidate pairs which survive the existing filters. Our algorithm outperforms alternative methods notably on real datasets.

Keywords： String similarity join Edit distance Filter and refine Data partition Combined frequency vectors

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A 0.20–2.43 GHz fractional-

Wei Zou, Daming Ren, Xuecheng Zou,weizou@hust.edu.cn,damingren@hust.edu.cn,estxczou@hust.edu.cn

Frontiers of Information Technology & Electronic Engineering 2021, Volume 22, Issue 2, Pages 141-286 doi: 10.1631/FITEE.1900653

Abstract: A 0.20–2.43 GHz fractional- is presented for multi-band wireless communication systems, in which the scheme adopts low voltage-controlled oscillators (VCOs) and a with reduced . VCOs that determine the out-band of a phase-locked loop (PLL) based are optimized using an automatic amplitude control technique and a high-quality factor figure-8-shaped inductor. A CP with a mismatch suppression architecture is proposed to improve the current match of the CP and reduce the PLL phase errors. Theoretical analysis is presented to investigate the influence of the on the output performance of PLLs. Fabricated in a TSMC 0.18-µm CMOS process, the prototype operates from 0.20 to 2.43 GHz. The PLL synthesizer achieves an in-band of −96.8 dBc/Hz and an out-band of −122.8 dBc/Hz at the 2.43-GHz carrier. The root-mean-square jitter is 1.2 ps under the worst case, and the measured reference spurs are less than −65.3 dBc. The current consumption is 15.2 mA and the die occupies 850 µm×920 µm.

Keywords： Frequency synthesizer Charge pump (CP) Voltage-controlled oscillator (VCO) Current mismatch Phase noise

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Frequency-Domain Full-Waveform Inversion Based on Tunnel Space Seismic Data Article

Mingyu Yu,Fei Cheng,Jiangping Liu,Daicheng Peng,Zhijian Tian

Engineering 2022, Volume 18, Issue 11, Pages 197-206 doi: 10.1016/j.eng.2021.06.018

Abstract:

Tunnel seismic detection methods are effective for obtaining the geological structure around the tunnel face, which is critical for safe construction and disaster mitigation in tunnel engineering. However, there is often a lack of accuracy in the acquired geological information and physical properties ahead of the tunnel face in the current tunnel seismic detection methods. Thus, we apply a frequency-domain acoustic full-waveform inversion (FWI) method to obtain high-resolution results for the tunnel structure. We discuss the influence of the frequency group selection strategy and the tunnel observation system settings regarding the inversion results and determine the structural imaging and physical property parameter inversion of abnormal geological bodies ahead of the tunnel face. Based on the conventional strategies of frequency-domain acoustic FWI, we propose a frequency group selection strategy that combines a low-frequency selection covering the vertical wavenumber and a high-frequency selection of anti-aliasing. This strategy can effectively obtain the spatial structure and physical parameters of the geology ahead of the tunnel face and improve the inversion resolution. In addition, by linearly increasing the side length of the tunnel observation system, we share the influence of the length of the two sides of the observation systems of different tunnels on the inversion results. We determined that the inversion results are best when the side length is approximately five times the width of the tunnel face, and the influence of increasing the side observation length beyond this range on the inversion results can be ignored. Finally, based on this approach, we invert for the complex multi-stratum model, and an accurate structure and physical property parameters of the complex stratum ahead of the tunnel face are obtained, which verifies the feasibility of the proposed method.

Keywords： Tunnel seismic detection Full-waveform inversion Frequency select strategy Observation system