Investigation on performance of all optical buffer with large dynamical delay time based on cascaded double loop optical buffers     

王拥军  吴重庆  忻向军  余贶琭  张晓磊 《海洋学报(英文版)》2010,29(9)

Optical buffers are critical for optical signal processing in future optical packet-switched networks. In this paper, a theoretical study as well as an experimental demonstration on a new optical buffer with large dynamical delay time is carried out based on cascaded double loop optical buffers (DLOBs). It is found that pulse distortion can be restrained by a negative optical control mode when the optical packet is in the loop. Noise analysis indicates that it is feasible to realise a large variable delay range by cascaded DLOBs. These conclusions are validated by the experiment system with 4-stage cascaded DLOBs. Both the theoretical simulations and the experimental results indicate that a large delay range of 1--9999 times the basic delay unit and a fine granularity of 25 ns can be achieved by the cascaded DLOBs. The performance of the cascaded DLOBs is suitable for the all optical networks.  相似文献   

Faithful quantum secure direct communication protocol against collective noise     

杨静  王川  张茹 《海洋学报(英文版)》2010,29(11)

An improved quantum secure direct communication (QSDC) protocol is proposed in this paper. Blocks of entangled photon pairs are transmitted in two steps in which secret messages are transmitted directly. The single logical qubits and unitary operations under decoherence free subspaces are presented and the generalized Bell states are constructed which are immune to the collective noise. Two steps of qubit transmission are used in this protocol to guarantee the security of communication. The security of the protocol against various attacks are discussed.  相似文献   

Progress in the Research on the Impact of Wind Farms on Climate and Environment     

Junxia Jiang  Liwei Yang  Zhenchao Li  Xiaoqing Gao 《地球科学进展》2019,34(10):1038-1049

Wind power has become one of the fastest growing renewable energy. With the large-scale deployment of wind farms in the world, people have started to pay attention to the impact of wind farms on the ecological environment and climate. This paper summarized the impact of wind farms on climate and ecological environment by investigating relevant literature: In the areas of wind farms, on the one hand, the set-up of wind turbines changes original aerodynamic roughness height and strengthens the dragging of the land surface against turbulence, directly affecting the turbulent motion of the boundary layer, resulting in the changes of intensity and pattern of material energy and water vapor exchange between land surface and near-surface atmosphere, further affecting the atmospheric circulation and climate. On the other hand, wind turbines convert the majority of the wind kinetic energy into electric energy, which produces the wake effect of the wind turbine. The budget patterns and spatial and temporal distribution of large-scale kinetic energy in the boundary layer are changed correspondingly, generating changes in various fluxes (heat flux, water vapor flux, etc.) in the atmosphere, which affect temperature, precipitation, and wind speed. Generally, the warming or cooling effect of wind farms on the near-surface is related to the stability of atmosphere. However, simulations in the global climate model showed that the average impact of wind farms on global climate is small, much smaller than the expected changes in greenhouse gas emissions and the interannual changes in natural climate.Wind power emits almost no carbon dioxide and pollutants. Compared with other traditional energy sources, it reduces water consumption but may generate some negative ecological impacts such as animal habitats, bird collisions, and noise, vision impact. However, some measures can be taken to mitigate these adverse effects.  相似文献   

吉林台网测震台站监测效能评估   总被引：1，自引：0，他引：1  

康建红  张宇  郑国栋  张晨侠 《防灾减灾学报》2014,(4):74-77

由于种种原因,台站地震计的固有周期、阻尼、灵敏度、观测动态范围等参数和台基噪声在运行的过程中会发生变化。本文用阶跃标定和计算观测动态范围、台基噪声功率谱的方法,得到吉林测震台网各台站地震计参数和台基噪声的变化情况,掌握吉林测震台网各台站的监测能力,为以后吉林测震台网的建设和发展提出建议。  相似文献   

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韩厚增  王坚  马昌中 《大地测量与地球动力学》2012,32(1):123-126

???????????????????????????￡????GPS???????????????У???????????е???????????????????????????????????????????????????????????????????????????????в????з????????????????????5?????????FFT??????????в??????????????????????????????????????????????е?????????????????????????????FFT????????????????????????????????????????GPS????????????????????????????????  相似文献   

黑龙江省延迟型低温冷害气候指标研究   总被引：2，自引：0，他引：2  

李帅  陈莉  王晾晾  万琳琳 《气象与环境学报》2014,30(4):79-83

针对影响黑龙江省农业生产的延迟型低温冷害,探讨前人提出的东北地区低温冷害气候指标在黑龙江省的适用性,借鉴前人经验,考虑玉米和水稻种植面积不断北扩等因素,确定黑龙江省延迟型性低温冷害气候指标的技术路线、判识临界值和计算方案。利用1961-2012年黑龙江省27个气象台站5-9月平均气温,以热量指数距平冷害判识指标为参照,考虑低温冷害指标与纬度、经度和海拔高度的密切关系,采用逐步回归法建立黑龙江省延迟型低温冷害气候指标;经过验证,表明该指标判识的低温冷害年与黑龙江省低温冷害的实际和发生规律相符,可作为监测指标;该指标所需数据量小,计算简便,具有实用性和推广价值;可采用该指标对黑龙江省低温冷害的历史发生规律进行分析。  相似文献   

百58井区地震数据高分辨率成像与断裂带构造特征     

赵玉莲  李录明  王海燕  胡自多  马建华  李斐 《吉林大学学报(地球科学版)》2011,41(4):1219-1225

准噶尔盆地西北缘百口泉地区百58井区是一个被多条断裂切割的复杂断块区,地层倾角变化大;现有的三维地震资料成果剖面上地震波组连续性差,断裂带附近资料成像模糊,地层接触关系不清楚,很难进行精细构造解释。为获得研究区沉积盖层精细结构,在详细分析原始地震资料特点和存在问题的基础上,有针对性地采用叠前多域去噪和非线性叠前时间偏移等多种处理技术,对已有的三维地震资料进行了高分辨率精细成像处理。新的成果剖面揭示出该区百－乌断裂带发育特征、空间展布及平面组合关系。根据地层厚度、构造特征、地震反射波组特征等,划分该区地层为二叠系、三叠系、侏罗系－白垩系三大构造层,以三大构造层不同的构造特征为依据确定了研究区分为西部推覆构造带、中部断阶构造带和东部斜坡构造带3个构造单元。  相似文献   

具有先验信息的地面三维激光扫描地形测量数据去噪算法     

赵鑫  吴侃  蔡来良 《大地测量与地球动力学》2011,31(4):107-111

为防止三维激光扫描数据中的噪声对实景重构造成扭曲,基于消噪的相关理论,提出了3种具有先验信息的去噪算法,利用高程注记点所提供的先验信息作为去噪依据,分别对比高程插值、最小二乘拟合平面及趋势面,选取适当阈值消去噪声。利用Timble GX200地面三维激光扫描系统获取的地形测量数据进行实验分析,结果表明:高程注记点可以作为先验信息为点云去噪提供依据,并确保去噪后基本符合实体特征。  相似文献   

基于小波变换与小波包变换的降噪方法比较   总被引：1，自引：0，他引：1  

曾宪伟  赵卫明  许晓庆 《地震地磁观测与研究》2010,31(4):14-19

在模拟地震记录信号中加入信噪比为17的高斯白噪声,然后分别采用小波降噪和小波包降噪方法,对含噪信号进行降噪处理。在不同降噪阈值下,比较降噪后信号的信噪比。结果表明:在同一降噪阈值下,小波包降噪后信号的信噪比高于小波降噪后信号的信噪比,而且采用wbmpen方法给定的阈值明显可以提高降噪后信号的信噪比。  相似文献   

地动噪声功率谱及动态范围的一致性分析   总被引：1，自引：1，他引：0  

段天山  袁顺 《地震地磁观测与研究》2010,31(5):122-126

在和田地震台阵中心子台安放9台CMG-40T型短周期地震计,采用EDAS-24IP数据采集器进行数据采集。对同一时段观测数据的地动噪声功率谱、动态范围等参数进行测定,并对测定结果进行对比,在使用者的角度分析该类型地震计的一致性。  相似文献