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坚硬岩石在强冲击荷载作用近区的性状研究 被引量:15
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作者 葛涛 王明洋 《爆炸与冲击》 EI CAS CSCD 北大核心 2007年第4期306-311,共6页
根据坚硬岩石的性质,利用力学模型分析了在冲击荷载作用下的岩石破坏过程,经由弹性状态向内摩擦状态的转变,最终达到流体力学状态。通过对内摩擦状态的分析,认为在强冲击荷载区域的变形近似为一维变形状态。冲击荷载作用在岩石中产生的... 根据坚硬岩石的性质,利用力学模型分析了在冲击荷载作用下的岩石破坏过程,经由弹性状态向内摩擦状态的转变,最终达到流体力学状态。通过对内摩擦状态的分析,认为在强冲击荷载区域的变形近似为一维变形状态。冲击荷载作用在岩石中产生的应力波可以看作类似于冲击波的短波,在波阵面附近的某个狭窄区域内将发生参数的急剧变化。根据近区变形状态与质量守恒导出了侵彻近区的速度场表达式。根据短波的研究,给出了近区应力波的衰减规律。 展开更多
关键词 爆炸力学 坚硬岩石 冲击荷载 内摩擦 短波
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New function of the Yb^(3+) ion as an efficient emitter of persistent luminescence in the short-wave infrared 被引量:13
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作者 Yan-Jie Liang Feng Liu +3 位作者 Ya-Fei Chen Xiao-Jun Wang Kang-Ning Sun Zhengwei Pan 《Light(Science & Applications)》 SCIE EI CAS CSCD 2016年第1期612-617,共6页
The trivalent ytterbium(Yb^(3+))ion has been extensively used as an emitter in short-wave infrared(SWIR)lasers,a sensitizer to activate other lanthanide ions for up-conversion luminescence,and a spectral converter in ... The trivalent ytterbium(Yb^(3+))ion has been extensively used as an emitter in short-wave infrared(SWIR)lasers,a sensitizer to activate other lanthanide ions for up-conversion luminescence,and a spectral converter in Ln^(3+)-Yb^(3+)doubly doped quantum cutting phosphors.Here we report a new function of the Yb^(3+)ion—as an efficient emitting center for SWIR persistent luminescence.We have developed the first real SWIR persistent phosphor,MgGeO3:Yb^(3+),which exhibits very-long persistent luminescence at around 1000 nm for longer than 100 h.The MgGeO3:Yb^(3+)phosphor is spectrally transparent to visible/near-infrared light(~400–900 nm)and is a promising ultraviolet-to-SWIR spectral convertor.The MgGeO3:Yb^(3+)phosphor also exhibits a photostimulated persistent luminescence capability,where the SWIR persistent emission in an ultraviolet-light pre-irradiated sample can be rejuvenated by low-energy light(white or red light)stimulation.The MgGeO3:Yb^(3+)phosphor is expected to have promising applications in biomedical imaging,night-vision surveillance and photovoltaics. 展开更多
关键词 persistent luminescence PHOTOSTIMULATION short-wave infrared(SWIR) ytterbium ions(Yb^(3+))
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Eye on the Sky: A UAP Research and Field Study off New York’s Long Island Coast
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作者 John Joseph Tedesco Gerald Thomas Tedesco 《Open Journal of Applied Sciences》 2024年第8期2267-2295,共29页
A ten-month field research study was meticulously conducted at Robert Moses State Park (RMSP) on the south shore of Long Island, NY. The objective was to determine if aerial phenomena of an unknown nature exist over a... A ten-month field research study was meticulously conducted at Robert Moses State Park (RMSP) on the south shore of Long Island, NY. The objective was to determine if aerial phenomena of an unknown nature exist over a coastal location and to characterize their properties and behaviors. Primary and secondary field observation methods were utilized in this data-centric study. Forensic engineering principles and methodologies guided the study. The challenges set forward were object detection, observation, and characterization, where multispectral electro-optical devices and radar were employed due to limited visual acuity and intermittent presentation of the phenomena. The primary means of detection utilized a 3 cm X-band radar operating in two scan geometries, the X- and Y-axis. Multispectral electro-optical devices were utilized as a secondary means of detection and identification. Data was emphasized using HF and LF detectors and spectrum analyzers incorporating EM, ultrasonic, magnetic, and RF field transducers to record spectral data in these domains. Data collection concentrated on characterizing VIS, NIR, SWIR, LWIR, UVA, UVB, UVC, and the higher energy spectral range of ionizing radiation (alpha, beta, gamma, and X-ray) recorded by Geiger-Müller counters as well as special purpose semiconductor diode sensors. 展开更多
关键词 Unidentified Anomalous Phenomenon (UAP) Forensic Techno-Signatures Office of the Director of National Intelligence (ODNI) Multispectral Electro-Optical (MEO) Ultraviolet A Radiation (UVA) Ultraviolet B Radiation (UVB) Ultraviolet C Radiation (UVC) Visible (VIS) Near-Infrared (NIR) short-wave Infrared (SWIR) Long-wave Infrared (LWIR) Low-Frequency (LF) High-Frequency (HF) Radio-Frequency (RF) Alpha Beta Gamma Ultrasonic X-Band Active Radar Kinematics Aerodynamics Luminous Spheroids Robert Moses State Park (RMSP)
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短波差分跳频系统序列译码的性能分析 被引量:8
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作者 熊俊俏 甘良才 朱毅超 《系统工程与电子技术》 EI CSCD 北大核心 2011年第2期399-403,共5页
基于短波差分跳频系统,提出了一种适于该系统的序列译码方法,并设计了适合序列译码的G函数。在加性白高斯噪声(additive white Gaussion noise,AWGN)信道和频率非选择性瑞利慢衰落信道条件下,对其比特误码率Pb性能进行了理论分析与数值... 基于短波差分跳频系统,提出了一种适于该系统的序列译码方法,并设计了适合序列译码的G函数。在加性白高斯噪声(additive white Gaussion noise,AWGN)信道和频率非选择性瑞利慢衰落信道条件下,对其比特误码率Pb性能进行了理论分析与数值仿真。仿真结果表明差分跳频的频率之间的相关性使其系统获得了一定的误跳纠正能力;如对于可用频率数为4、每跳传输1 bit的差分跳频系统,在AWGN信道条件下,当信噪比约为10 dB时,序列译码的Pb可达到10-4,相对于逐符号译码的性能改善为2.5 dB;在瑞利信道条件下,当信噪比约为18 dB时,序列译码的Pb可达到10-3,相对于逐符号译码的性能改善为15 dB,相对于逐符号译码,在短波差分系统中使用序列译码方法的效果更优。 展开更多
关键词 差分跳频 序列译码 逐符号译码 短波
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Portable Analyzer for Rapid Analysis of Total Protein, Fat and Lactose Contents in Raw Milk Measured by Non-dispersive Short-wave Near-infrared Spectrometry 被引量:6
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作者 FENG Xu-dong SU Rui XU Nan WANG Xing-hua YU Ai-min ZHANG Han-qi CAO Yan-bo 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2013年第1期15-19,共5页
A novel portable analyzer for raw milk quality control during the material purchase at dairy plants was developed, by which the percentages(mass fraction) of main components including total protein, fat, and lactose... A novel portable analyzer for raw milk quality control during the material purchase at dairy plants was developed, by which the percentages(mass fraction) of main components including total protein, fat, and lactose of an unhomogenized milk sample could be determinated in 1 min with the help of non-dispersive short-wave near-infrared (NDSWNIR) spectrometry in a wavelength range from 600 nm to 1100 nm and multivariate calibration. The analyzer was designed with a single-beam optical system, which comprised a temperature control module, a multi-channel narrow-band light source(16 wavelengths), a glass absorption cell with 15 mm sample thickness, a silicon photodiode detector, several compound lenses and a recorder module. A total of 80 raw milk samples were collected at a dairy farm twice a month for 4 months. The samples were scanned with a common UV-Vis-NIR spectrometer and analyzed according to China GB standard methods. The uninformative variables elimination(UVE) method was carried out on the spectrum data and the percentages of main components of all the samples to choose the peak emitting wavelength of each channel of the light source. Another 90 raw milk samples were collected from the same dairy farm thrice a month for 3 months. The samples were analyzed according to China GB standard methods and with the proposed analyzer. The percentages of the main components and the NDSWNIR absorption data of the samples were used for the construction and validation of the multivariate calibration model with partial least squares(PLS) method. The root-mean-square errors of prediction(RMSEP) of total protein, fat and lactose were 0.201, 0.172 and 0.247 and the coefficients of correlation(R) were 0.932, 0.981 and 0.933, respectively. 展开更多
关键词 Portable analyzer Raw milk Non-dispersive short-wave near-infrared(NDSWNIR) spectrometry Multiva-riate calibration
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Short-wave infrared InGaAs photodetectors and focal plane arrays 被引量:5
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作者 Yong-Gang Zhang Yi Gu +3 位作者 Xiu-Mei Shao Xue Li Hai-Mei Gong Jia-Xiong Fang 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第12期57-63,共7页
In this article, unique spectral features of short-wave infrared band of 1 μm–3 μm, and various applications related to the photodetectors and focal plane arrays in this band, are introduced briefly. In addition, t... In this article, unique spectral features of short-wave infrared band of 1 μm–3 μm, and various applications related to the photodetectors and focal plane arrays in this band, are introduced briefly. In addition, the different material systems for the devices in this band are outlined. Based on the background, the development of lattice-matched and wavelengthextended InGaAs photodetectors and focal plane arrays, including our continuous efforts in this field, are reviewed. These devices are concentrated on the applications in spectral sensing and imaging, exclusive of optical fiber communication. 展开更多
关键词 INGAAS short-wave infrared PHOTODETECTORS focal plane arrays
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Time-Resolved Imaging in Short-Wave Infrared Region
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作者 徐杨 李万万 《Journal of Shanghai Jiaotong university(Science)》 EI 2024年第1期29-36,共8页
Compared with the conventional first near-infrared(NIR-I,700900 nm)window,the short-wave infrared region(SWIR,900—1700nm)possesses the merits of the increasing tissue penetration depths and the suppression of scatter... Compared with the conventional first near-infrared(NIR-I,700900 nm)window,the short-wave infrared region(SWIR,900—1700nm)possesses the merits of the increasing tissue penetration depths and the suppression of scattering background,leading to great potential for in vivo imaging.Based on the limitations of the common spectral domain,and the superiority of the time-dimension,time-resolved imaging eliminates the auto-fuorescence in the biological tissue,thus supporting higher signal-to-noise ratio and sensitivities.The imaging technique is not affected by the difference in tissue composition or thickness and has the practical value of quan-titative in vivo detection.Almost all the relevant time-resolved imaging was carried out around lanthanide-doped upconversion nanomaterials,owing to the advantages of ultralong luminescence lifetime,excellent photostability,controllable morphology,easy surface modification and various strategies of regulating lifetime.Therefore,this review presents the research progress of SWIR time-resolved imaging technology based on nanomaterials doped with lanthanide ions as luminescence centers in recent years. 展开更多
关键词 time-resolved imaging short-wave infrared fluorescence probe lanthanide ions
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Paleoclimatic application of spectral parameters to the eolian red clay of the Jianzha Basin,northeastern margin of the Tibetan Plateau
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作者 Chaofeng FU Ju’e TIAN +6 位作者 Xinwen XU Yougui SONG Jun ZUO Feng WANG Lin CHEN Pengfei LI Xiaoke QIANG 《Science China Earth Sciences》 SCIE EI CAS CSCD 2024年第6期1952-1966,共15页
Reflectance spectroscopy is rapid,inexpensive,and non-destructive and can provide important information about the mineralogy of rocks and sediments.We measured the reflectance spectroscopy of Miocene red clay deposits... Reflectance spectroscopy is rapid,inexpensive,and non-destructive and can provide important information about the mineralogy of rocks and sediments.We measured the reflectance spectroscopy of Miocene red clay deposits on the northeastern margin of the Tibetan Plateau,with the aim of developing a rapid methodology for detecting paleoclimatic changes.We obtained visible/near-infrared(VNIR)and short-wave infrared(SWIR)spectroscopy data from the red clay in the Jianzha Basin,and analyzed their relationship with independent paleoclimatic records,including mineral contents and environmental magnetic parameters.The results show that the VNIR parameters,including D500,D900,R500,and R900(where D and R represent the depth and reflectance of the absorption peaks around 500 and 900 nm,respectively)are temperature-sensitive and correlated with the magnetic susceptibility,frequency-dependent magnetic susceptibility,and the marine δ^(18)O record.The results of frequency-domain analysis of the VNIR parameters show that they reflect climate change on orbital timescales.SWIR parameters,such as AS1400,D1400/D1900 and D1900(where AS represents the asymmetry of the absorption peaks around1400 nm),are correlated with the illite and montmorillonite content,and they are sensitive to the weathering intensity.The spectral parameters of the eolian red clay in the Jianzha Basin reflect regional climatic changes caused by the uplift of the Tibetan Plateau at~8.5 Ma and global climatic cooling at~7.2 Ma,and thus they are applicable as both regional and global paleoenvironmental indicators. 展开更多
关键词 Visible/near-infrared spectroscopy short-wave infrared spectroscopy Paleoclimatic indicators Red clay Tibetan Plateau
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High-performance GaSb planar PN junction detector
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作者 Yuanzhi Cui Hongyue Hao +13 位作者 Shihao Zhang Shuo Wang Jing Zhang Yifan Shan Ruoyu Xie Xiaoyu Wang Chuang Wang Mengchen Liu Dongwei Jiang Yingqiang Xu Guowei Wang Donghai Wu Zhichuan Niu Derang Cao 《Journal of Semiconductors》 EI CAS CSCD 2024年第9期48-52,共5页
This paper examines GaSb short-wavelength infrared detectors employing planar PN junctions. The fabrication was based on the Zn diffusion process and the diffusion temperature was optimized. Characterization revealed ... This paper examines GaSb short-wavelength infrared detectors employing planar PN junctions. The fabrication was based on the Zn diffusion process and the diffusion temperature was optimized. Characterization revealed a 50% cut-off wavelength of 1.73 μm, a maximum detectivity of 8.73 × 10^(10) cm·Hz^(1/2)/W, and a minimum dark current density of 1.02 × 10^(-5) A/cm^(2).Additionally, a maximum quantum efficiency of 60.3% was achieved. Subsequent optimization of fabrication enabled the realization of a 320 × 256 focal plane array that exhibited satisfactory imaging results. Remarkably, the GaSb planar detectors demonstrated potential in low-cost short wavelength infrared imaging, without requiring material epitaxy or deposition. 展开更多
关键词 ANTIMONIDE short-wave infrared planar junction zinc diffusion
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SWIR FluorescenceImaging In Vivo Monitoring and Evaluating Implanted M2 Macrophages in Skeletal Muscle Regeneration
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作者 Mo Chen Yuzhou Chen +9 位作者 Sijia Feng Shixian Dong Luyi Sun Huizhu Li Fuchun Chen Nguyen Thi Kim Thanh Yunxia Li Shiyi Chen You Wang Jun Chen 《Engineering》 SCIE EI CAS CSCD 2024年第2期283-294,共12页
Skeletal muscle has a robust regeneration ability that is impaired by severe injury,disease,and aging.resulting in a decline in skeletal muscle function.Therefore,improving skeletal muscle regeneration is a key challe... Skeletal muscle has a robust regeneration ability that is impaired by severe injury,disease,and aging.resulting in a decline in skeletal muscle function.Therefore,improving skeletal muscle regeneration is a key challenge in treating skeletal muscle-related disorders.Owing to their significant role in tissue regeneration,implantation of M2 macrophages(M2MФ)has great potential for improving skeletal muscle regeneration.Here,we present a short-wave infrared(SWIR)fluorescence imaging technique to obtain more in vivo information for an in-depth evaluation of the skeletal muscle regeneration effect after M2MФtransplantation.SWIR fluorescence imaging was employed to track implanted M2MФin the injured skeletal muscle of mouse models.It is found that the implanted M2MФaccumulated at the injury site for two weeks.Then,SWIR fluorescence imaging of blood vessels showed that M2MФimplantation could improve the relative perfusion ratio on day 5(1.09±0.09 vs 0.85±0.05;p=0.01)and day 9(1.38±0.16 vs 0.95±0.03;p=0.01)post-injury,as well as augment the degree of skeletal muscle regencration on day 13 post-injury.Finally,multiple linear regression analyses determined that post-injury time and relative perfusion ratio could be used as predictive indicators to evaluate skeletal muscle regeneration.These results provide more in vivo details about M2MФin skeletal muscle regeneration and confirm that M2MФcould promote angiogenesis and improve the degree of skeletal muscle repair,which will guide the research and development of M2MФimplantation to improve skeletal muscle regeneration. 展开更多
关键词 In vivo short-wave infrared Skeletal muscle MACROPHAGE REGENERATION
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短波天波通信链路计算模型研究 被引量:5
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作者 王琴 黄金权 《通信技术》 2010年第10期14-16,共3页
为建立远程舰艇短波通信可靠通信链路,简化短波通信工程中天线和通信台站设计过程,研究设计了一个完整的短波通信链路计算模型。该模型包含天线辐射特性计算模型、短波通信电路计算模型、短波天线数据库和通信链路地理参数数据库四大部... 为建立远程舰艇短波通信可靠通信链路,简化短波通信工程中天线和通信台站设计过程,研究设计了一个完整的短波通信链路计算模型。该模型包含天线辐射特性计算模型、短波通信电路计算模型、短波天线数据库和通信链路地理参数数据库四大部分。在此基础上,使用该模型进行了实例分析,确定了在一定条件下的工作频率、反射模式,预估场强强度,为短波天波通信工程设计提供依据。 展开更多
关键词 短波 电离层 通信链路 太阳黑子 场强中值
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Mineralogical evidence of water activity in the northern lowlands of Mars based on inflight-calibrated spectra from the Zhurong rover 被引量:1
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作者 Honglei LIN Yangting LIN +4 位作者 Yong WEI Sheng GOU Chi ZHANG Renhao RUAN Yongxin PAN 《Science China Earth Sciences》 SCIE EI CAS CSCD 2023年第11期2463-2472,共10页
Hydrated minerals provide direct indications of the early Martian water environment. The various clay minerals and evaporite salts found to date are mainly exposed in the ancient southern highlands of Mars. While it i... Hydrated minerals provide direct indications of the early Martian water environment. The various clay minerals and evaporite salts found to date are mainly exposed in the ancient southern highlands of Mars. While it is believed that the area of the northern lowlands could have hosted a global ocean in the past, its surface is covered with a layer of spectrally nonabsorbing materials, and orbital hyperspectral remote sensing has found only sparse evidence for the presence of water. China's first Mars exploration mission, Tianwen-1, landed in the putative ancient shoreline zone of the northern lowlands of Mars. Its rover,Zhurong, conducted high-spatial-resolution reconnaissance to reveal the geological and environmental evolution of this region.Owing to frequent dust storms, not only is the Martian surface covered with dust, but also the spectral calibration panels on the rover are affected by dust coverage. Data from the shortwave infrared(SWIR) spectrometer onboard the rover are also affected by other environmental factors such as instrumental temperature changes and atmospheric carbon dioxide absorption. This study recalibrated the in situ SWIR data to minimize the impact of the above factors. The recalibrated spectral data show that the reflectance of the landing area falls within the normal range of Martian soil, and confirm the presence of several important absorption peaks. The absorption characteristics indicate the presence of polyhydrated sulfates, gypsum, and hydrated silicates in the surface materials along the rover track, with sulfate content of <27–39 wt.%. Our results further confirm past activity of liquid water in the Zhurong rover landing area, providing mineralogical evidence supporting hypotheses related to underground water or an ancient shoreline. 展开更多
关键词 MARS Water activity In-situ exploration short-wave infrared spectrum Zhurong rover
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On-chip short-wave infrared multispectral detector based on integrated Fabry–Perot microcavities array 被引量:3
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作者 Zhiyi Xuan Qingquan Liu +5 位作者 Zhuangzhuang Cui Songlei Huang Bo Yang Chenlu Li Shaowei Wang Wei Lu 《Chinese Optics Letters》 SCIE EI CAS CSCD 2022年第6期25-29,共5页
We demonstrate an ultra-compact short-wave infrared[SWIR]multispectral detector chip by monolithically integrating the narrowband Fabry–Perot microcavities array with the In Ga As detector focal plane array.A 16-chan... We demonstrate an ultra-compact short-wave infrared[SWIR]multispectral detector chip by monolithically integrating the narrowband Fabry–Perot microcavities array with the In Ga As detector focal plane array.A 16-channel SWIR multispectral detector has been fabricated for demonstration.Sixteen different narrowband response spectra are acquired on a 64×64 pixels detector chip by four times combinatorial etching processes.The peak of the response spectra varies from1450 to 1666 nm with full width at half-maximum of 24 nm on average.The size of the SWIR multispectral detection system is remarkably reduced to a 2 mm^(2) detector chip. 展开更多
关键词 short-wave infrared DETECTOR multi-spectra MICRO-CAVITY ON-CHIP
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短波AX.25分组无线网方案及协议实现 被引量:4
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作者 赵冬梅 冯锡生 《数字通信》 1997年第3期10-13,23,共5页
介绍用AX.25协议构成短波分组无线网分案,分析了AX.25的协议内容,给出AX.25协议通信控制器的硬件和软件实现方法.
关键词 分组无线网 协议 AX.25 无线通信
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On the exact solutions to the long short-wave interaction system 被引量:1
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作者 范慧玲 范雪飞 李欣 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第2期25-28,共4页
The complete discrimination system for polynomial method is applied to the long-short-wave interaction system to obtain the classifications of single traveling wave solutions. Compared with the solutions given by the ... The complete discrimination system for polynomial method is applied to the long-short-wave interaction system to obtain the classifications of single traveling wave solutions. Compared with the solutions given by the (G~/G)-expansion method, we gain some new solutions. 展开更多
关键词 single traveling wave solution complete discrimination system for polynomial method long- short-wave interaction system
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短波跳频系统中分组Turbo码在阻塞干扰下的性能分析 被引量:2
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作者 甘良才 蒋光明 马斌 《电子与信息学报》 EI CSCD 北大核心 2003年第6期795-800,共6页
该文基于短波跳频(FH)系统的特点,对短波跳频系统中分组 Turbo码的联合上界进行了分析和推导,给出了该编码在阻塞干扰存在的情况时平均误码率上限的数学表达式。并对分组 Turbo码在短波阻塞信道下的性能进行了数值模拟,结果表明:分组 Tu... 该文基于短波跳频(FH)系统的特点,对短波跳频系统中分组 Turbo码的联合上界进行了分析和推导,给出了该编码在阻塞干扰存在的情况时平均误码率上限的数学表达式。并对分组 Turbo码在短波阻塞信道下的性能进行了数值模拟,结果表明:分组 Turbo码用于跳频系统时,在短波慢瑞利衰落的信道下,当信噪比为 20dB,信号阻塞比为 30dB时,可使系统的比特误码率由 10^(-3)降为 10^(-5)。 展开更多
关键词 短波跳频系统 分组TURBO码 阻塞干扰 FH 短波 联合上界 平均误码率 信噪比
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短波战术跳频通信系统的技术现状和发展 被引量:1
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作者 孙剑川 凌涛 《通信与广播电视》 2002年第3期1-6,共6页
本文论述了当代短波战术跳频通信系统的技术现状,指出和分析了当前该技术领域存在问题,并在此基础上对该系统的发展提出了新的见解和有益的建议。
关键词 技术现状 发展 短波 跳频通信
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基于Matlab的短波差分跳频通信仿真设计与实现 被引量:3
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作者 滕振宇 冯永新 +1 位作者 隋涛 田明浩 《沈阳理工大学学报》 CAS 2010年第5期17-20,71,共5页
差分跳频通信系统作为一种全新概念的通信系统,已成为当前短波保密通信的一个重要发展方向。鉴于此,在对短波差分跳频通信机理研究基础上,通过建立基于m序列的G函数、G-1函数设计方案及加窗FFT检测设计方案,实现了基于Matlab的短波差分... 差分跳频通信系统作为一种全新概念的通信系统,已成为当前短波保密通信的一个重要发展方向。鉴于此,在对短波差分跳频通信机理研究基础上,通过建立基于m序列的G函数、G-1函数设计方案及加窗FFT检测设计方案,实现了基于Matlab的短波差分跳频通信通信过程仿真。仿真结果表明,该通信过程仿真可有效实现差分跳频通信系统的信号生成、检测及接收仿真功能,验证了设计方案的正确性。可为短波差分跳频通信技术的发展提供理论借鉴及测试环境. 展开更多
关键词 短波 差分跳频 MATLAB 仿真
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短波LFM信号宽带识别算法 被引量:3
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作者 刁文静 张志勤 《无线电工程》 2011年第10期55-57,60,共4页
在深入分析线性调频(Linear Frequency Modem,LFM)信号特征和短波信道环境基础上,针对短波信道中LFM提出了一种宽带自动侦察和参数估计新算法。该算法合理规避了宽带信号转窄带信号处理过程中滤波器难于实现和运算量大的问题,并在兼顾... 在深入分析线性调频(Linear Frequency Modem,LFM)信号特征和短波信道环境基础上,针对短波信道中LFM提出了一种宽带自动侦察和参数估计新算法。该算法合理规避了宽带信号转窄带信号处理过程中滤波器难于实现和运算量大的问题,并在兼顾运算速度和设备量的基础上,保证了算法的工作性能。仿真结果表明,在信噪比大于6 dB情况下该算法能从宽带信号中有效的识别出LFM信号,并估计出LFM信号的起始频率、调频斜率和带宽等调制参数。 展开更多
关键词 短波 宽带 LFM 侦察
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A Short-wave UV Nonlinear Optical Sulfate of High Thermal Stability 被引量:3
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作者 LI Yan-Qiang LUO Jun-Hua +1 位作者 JI Xiang-Hai ZHAO San-Gen 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2020年第3期485-492,377,共9页
Compared with borates, carbonates, nitrates and phosphates, sulfates have been ignored as nonlinear optical(NLO) materials for a long time. Recently, researchers started to realize sulfates which have the potential as... Compared with borates, carbonates, nitrates and phosphates, sulfates have been ignored as nonlinear optical(NLO) materials for a long time. Recently, researchers started to realize sulfates which have the potential as NLO materials, and synthesized some sulfate NLO materials by the water solution method and solvothermal method. However, all these sulfate NLO materials have the same problem of low thermal stability. Here, we synthesized a new Cs4 Mg6(SO4)8, which crystallizes in the orthorhombic space group P212121 with a = 9.102, b = 9.955, c = 16.127 ?, V = 1461.3 ?3, Z = 2, F(000) = 1352, μ = 5.777 mm-1, R = 0.0213 and wR = 0.0480. The single crystal structure can be described as a three-dimensional framework constructed by MgO6 octahedra and SO4 tetrahedra. Relevant optical measurements indicate that Cs4 Mg6(SO4)8 is short-wave ultraviolet transparent and has a moderate second harmonic generation response. Theoretical calculations by the CASTEP package reveal that S–O groups are NLO-active anionic groups. Significantly, Cs4 Mg6(SO4)8 has high thermal stability up to 781 ℃ based on thermal analyses. We believe that our work will provide a new strategy for researchers to develop new sulfate short-wave ultraviolet NLO materials of high thermal stability. 展开更多
关键词 sulfates NONLINEAR optical materials THERMAL stability short-wave ULTRAVIOLET FLUX method
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