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基于单频数据重构散射障碍的新型线性采样方法
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作者 丁濛 《工程数学学报》 CSCD 北大核心 2020年第5期583-590,共8页
散射及反散射的数学理论与计算一直是应用数学领域中的重要课题,其成果在地质勘探、无损探测、医学成像等领域都具有广泛的应用.线性采样方法(LSM)是近年来反散射理论中一类非常流行的非迭代型重建算法,但是这种方式很难推广到如半空间... 散射及反散射的数学理论与计算一直是应用数学领域中的重要课题,其成果在地质勘探、无损探测、医学成像等领域都具有广泛的应用.线性采样方法(LSM)是近年来反散射理论中一类非常流行的非迭代型重建算法,但是这种方式很难推广到如半空间中障碍反散射等更为复杂的问题中.本文基于单频数据研究Dirichlet障碍反散射问题的数值重建算法.通过构造带有阻尼边界条件的辅助边值问题,提出了一类新型的线性采样方法,并在理论上严格证明了该方法在任意给定的波数下重构障碍形状及位置的有效性. 展开更多
关键词 反散射 Dirichlet障碍 线性采样方法 单频数据
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用单频GPS数据实现低轨卫星动力学法定轨研究
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作者 张德成 郑作亚 +1 位作者 王霞迎 李伟 《导航定位学报》 2014年第1期23-26,共4页
采用星载GPS双频观测数据,低轨卫星定轨的精度可以达到厘米级。采用GRACE A卫星的星载GPS观测数据,分别基于单频数据(C/A和L1)的半合组合观测量和双频数据的消电离层组合观测量,采用动力学低轨卫星定轨方法,解算了7d的GRACE A卫星轨道,... 采用星载GPS双频观测数据,低轨卫星定轨的精度可以达到厘米级。采用GRACE A卫星的星载GPS观测数据,分别基于单频数据(C/A和L1)的半合组合观测量和双频数据的消电离层组合观测量,采用动力学低轨卫星定轨方法,解算了7d的GRACE A卫星轨道,解算结果与德国地学中心发布的快速科学轨道进行对比分析,并通过卫星激光测距观测数据进行检核。结果表明,通过半合组合观测量定轨得到的结果,在径向R、切向T、法向N方向的均方根误差平均值分别为7.9cm、20.1cm和5.5cm,三维定轨精度平均为22.8cm,利用卫星激光测距数据进行检核,残差平均值为-1.8cm,均方根误差为8.6cm。证明了采用单频观测数据进行定轨的可行性,并且定轨精度可以达到一般低轨卫星定轨精度的要求。 展开更多
关键词 单频数据 半合组合观测量 动力学 低轨卫星定轨
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基于区块链技术的地面数字电视单频网运维设计 被引量:2
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作者 杨方正 盛国芳 +2 位作者 徐博源 胡军 张宇 《广播与电视技术》 2020年第11期90-96,共7页
随着区块链技术的发展,越来越多行业开始重视区块链技术的应用。在广电领域,地面数字电视单频网运维还处于研究起步阶段,而区块链技术的特性非常适合在地面数字电视单频网运维中应用。本文概括介绍了区块链技术、地面数字电视单频网系统... 随着区块链技术的发展,越来越多行业开始重视区块链技术的应用。在广电领域,地面数字电视单频网运维还处于研究起步阶段,而区块链技术的特性非常适合在地面数字电视单频网运维中应用。本文概括介绍了区块链技术、地面数字电视单频网系统,并在此基础上设计了基于区块链技术的单频网运维系统总体架构,对单频网区块链进行了具体描述。同时分析了应用区块链技术的单频网运维设计思想,以及实现瓶颈。 展开更多
关键词 地面数字电视 单频网运维 区块链 单频网区块链 单频网监测数据区块链 单频网延时区块链
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基于单频星载GPS数据的周跳探测方法 被引量:1
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作者 夏博洋 管守奎 +2 位作者 黄杰 虞顺 陆振波 《测绘地理信息》 2016年第4期27-31,共5页
在星载GPS测量中,载波相位观测数据的周跳探测是实现低轨卫星高精度定轨的关键,而传统的周跳探测方法受低轨卫星轨道特性的影响并不能很好地处理星载GPS数据。在总结传统周跳探测方法的基础上研究了一种利用最小二乘及假设检验的周跳探... 在星载GPS测量中,载波相位观测数据的周跳探测是实现低轨卫星高精度定轨的关键,而传统的周跳探测方法受低轨卫星轨道特性的影响并不能很好地处理星载GPS数据。在总结传统周跳探测方法的基础上研究了一种利用最小二乘及假设检验的周跳探测方法,该方法采用历元间载波相位差分观测值构建观测方程,利用最小二乘求解并建立周跳检测量,根据假设检验探测周跳,适用于采样率较高条件下的单频星载GPS载波相位数据的周跳探测。以实测星载GPS数据周跳探测试验验证了该方法的有效性,试验结果表明,当可观测的GPS卫星数大于5颗时,该方法能够探测出1周左右的周跳,并确定发生周跳的卫星。 展开更多
关键词 星载 单频数据 周跳探测 最小二乘 假设检验
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A parallel memory architecture for video coding
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作者 Jian-ying PENG Xiao-lang YAN +1 位作者 De-xian LI Li-zhong CHEN 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2008年第12期1644-1655,共12页
To efficiently exploit the performance of single instruction multiple data (SIMD) architectures for video coding, a parallel memory architecture with power-of-two memory modules is proposed. It employs two novel ske... To efficiently exploit the performance of single instruction multiple data (SIMD) architectures for video coding, a parallel memory architecture with power-of-two memory modules is proposed. It employs two novel skewing schemes to provide conflict-free access to adjacent elements (8-bit and 16-bit data types) or with power-of-two intervals in both horizontal and vertical directions, which were not possible in previous parallel memory architectures. Area consumptions and delay estimations are given respectively with 4, 8 and 16 memory modules. Under a 0.18-pm CMOS technology, the synthesis results show that the proposed system can achieve 230 MHz clock frequency with 16 memory modules at the cost of 19k gates when read and write latencies are 3 and 2 clock cycles, respectively. We implement the proposed parallel memory architecture on a video signal processor (VSP). The results show that VSP enhanced with the proposed architecture achieves 1.28× speedups for H.264 real-time decoding. 展开更多
关键词 Single instruction multiple data (SIMD) Video coding Parallel memory Skewing scheme
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Estimation Method of Center of Inertia Frequency Based on Phasor Measurement Data
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作者 Takuhei Hashiguchi Masayuki Watanabe +4 位作者 Tadahiro Goda Yasunori Mitani Osamu Saeki Masahide Hojo Hiroyuki Ukai 《Journal of Energy and Power Engineering》 2012年第3期434-445,共12页
In the world, recent increased disturbances, congestion management problems, and increases of complexity in operating power systems have brought the need for integrations and improvements of power systems. Advanced ap... In the world, recent increased disturbances, congestion management problems, and increases of complexity in operating power systems have brought the need for integrations and improvements of power systems. Advanced applications in WAMPAC (wide area monitoring, protection, and control) systems provide a cost effective solution to improve system planning, operation, maintenance, and energy trading. Synchronized measurement technology and the application are an important element of WAMPAC. In addition, PMUs (phasor measurement units) are the most accurate and advanced time-synchronized technology available for WAMPAC application. Therefore, the original measurement system of PMUs has been constructed in Japan. This paper describes the estimation method of a center of inertia frequency by applying actual measurement data. The application of this method enables us to extract power system oscillations from measurement data appropriately. Moreover, this proposed method will help to the clarification of power system dynamics and this application will make it possible to realize the monitoring of power system oscillations associated with the power system stability. 展开更多
关键词 Phasor measurement unit power system oscillations signal processing center of inertia frequency monitoring.
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A method to estimate crop effects at higher frequencies by modeling and microwave radiometric data 被引量:2
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作者 ZHANG ZhongJun ZHANG LiXin +1 位作者 SUN GuoQing LIU QinHuo 《Science China Earth Sciences》 SCIE EI CAS 2012年第7期1159-1165,共7页
To use the 0th-order τ-ω model to retrieve soil moisture from radiometric data at frequencies higher than the C band, the characteristics of the effective single scattering albedo ω and the opacity rof vegetation m... To use the 0th-order τ-ω model to retrieve soil moisture from radiometric data at frequencies higher than the C band, the characteristics of the effective single scattering albedo ω and the opacity rof vegetation must be studied. In this paper, the co and r values of corn for the C, X, and Ku bands were retrieved by matching the simulations of a high-order matrix-doubling model to the τ-ω model. First, the brightness temperature of the matrix-doubling was validated by a truck-mounted radiometer in a field experiment, where the vegetation emission contributions were validated with aluminum foil to mask the soil emission. Then an emissivity database of corn fields for different growing seasons was established for a variety of soil conditions. With the transmissivity of corn determined from the database, the effective single scattering albedos of corn for different heights at the C, X, and Ku bands and at a 55° viewing angle were derived. To verify the accuracy of the derived co and τ values, we used SMEX02/PSR aircraft data and the Qp model to retrieve the soil moisture; the RMSE between the retrieval and the measurements was 4.76% at the C band and 5.36% at the X band. 展开更多
关键词 microwave emission single scattering albedo TRANSMISSIVITY VEGETATION matrix-doubling
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