A novel algorithm is proposed to solve the poor per- formance problem of the Tent chaos-based frequency modulation （FM） signal for range-Doppler imaging, which takes it into complex multi-segment system by increasin...A novel algorithm is proposed to solve the poor per- formance problem of the Tent chaos-based frequency modulation （FM） signal for range-Doppler imaging, which takes it into complex multi-segment system by increasing its segments. The simulation results show that the effectiveness of the proposed algorithm, as well as the performance of the improved Tent FM signal is obvious in a multipath or noise propagation environment.展开更多
随着“耳朵经济”“声”气蓬勃地发展,无论是泛播客平台还是分众化播客平台都显示出巨大的发展潜力。泛播客与分众化播客“殊途同归”的成功背后暗含着的是二者不同的运营模式,分析二者不同运营模式或可为播客平台差异化竞争提供一些参...随着“耳朵经济”“声”气蓬勃地发展,无论是泛播客平台还是分众化播客平台都显示出巨大的发展潜力。泛播客与分众化播客“殊途同归”的成功背后暗含着的是二者不同的运营模式,分析二者不同运营模式或可为播客平台差异化竞争提供一些参考。本文藉此分别选取了喜马拉雅与蜻蜓FM作为泛播客与分众化播客的代表案例,分析其在内容运营模式、分发模式、盈利模式等方面的差异,并分析其共有困境与未来发展路径。With the vigorous development of “ear economy”, both general podcasting platforms and niche podcasting platforms have shown great potential for development. Behind the success of general podcasting and niche podcasting, different operation modes are implied, and analyzing the different operation modes of the two may provide some references for the differentiated competition of podcasting platforms. In this paper, Himalaya and Dragonfly FM are selected as the representative cases of pan-podcasting and niche podcasting to analyze their differences in content operation mode, distribution mode, profit model, etc., and analyze their common difficulties and future development paths.展开更多
在不增加设备体积重量以及提高发射功率的前提下,为满足高码率遥测数据传输的需求,现有的脉冲编码调制-频调(Pulse Code Modulation Frequency Modulation, PCM-FM)遥测系统广泛使用多符号检测(Multiple Symbol Detection, MSD)算法和Tu...在不增加设备体积重量以及提高发射功率的前提下,为满足高码率遥测数据传输的需求,现有的脉冲编码调制-频调(Pulse Code Modulation Frequency Modulation, PCM-FM)遥测系统广泛使用多符号检测(Multiple Symbol Detection, MSD)算法和Turbo乘积码(TPC)技术。调制指数是PCM-FM遥测系统中的重要参数之一,对系统带宽和误码率有重要影响。本文分析了MSD多符号检测算法原理,通过计算互相关系数及Matlab仿真,分析了调制指数大小对带宽和误码率的影响,指出将调制指数设置为0.715较为合适;分析了调制指数偏差对信噪比损耗的影响,利用MSD算法的相位网格图分析了调制指数偏差对误码和码同步的影响,指出随机数据比连“0”或连“1”数据具有更好的容忍能力。展开更多
Chaos-based encryption schemes have been studied extensively, while the security analysis methods for them are still problems to be resolved. Based on the periodic orbit theory, this paper proposes a novel security an...Chaos-based encryption schemes have been studied extensively, while the security analysis methods for them are still problems to be resolved. Based on the periodic orbit theory, this paper proposes a novel security analysis method. The periodic orbits theory indicates that the fundamental frequency of the spiraling orbits is the natural frequency of associated linearized system, which is decided by the parameters of the chaotic system. Thus, it is possible to recover the plaintext of secure communication systems based on chaotic shift keying by getting the average time on the spiraling orbits. Analysis and simulation results show that the security analysis method can break chaos shift keying secure communication systems, which use the parameters as keys.展开更多
With the massive increase of wirelessly connected devices and the rapid development of the Internet, information is transmitted more and more frequently. Since the information transmissions over these networks are gre...With the massive increase of wirelessly connected devices and the rapid development of the Internet, information is transmitted more and more frequently. Since the information transmissions over these networks are greatly threatened not only by the imperfection of channels but also by the potential attackers or eavesdroppers, security and reliability become some of the crucial requirements for our future networks. Due to the complex dynamic behavior, ergodicity, wide spectrum and sensitivity to initial values, chaos signals show most required attributes of good cryptosystems and great potentials in optical fiber communications for desirable spatial accuracy and distance. In this context, it has become imperative to investigate and apply chaos theories to solve emerging secure communication problems in various networks. This includes leveraging chaos systems and signals to address a wide range of secure communication challenges in optical fiber communications, chaos cipher, image encryption, etc.展开更多
基金supported by the National Natural Science Foundation of China (610320106110117211076006)
文摘A novel algorithm is proposed to solve the poor per- formance problem of the Tent chaos-based frequency modulation （FM） signal for range-Doppler imaging, which takes it into complex multi-segment system by increasing its segments. The simulation results show that the effectiveness of the proposed algorithm, as well as the performance of the improved Tent FM signal is obvious in a multipath or noise propagation environment.
文摘随着“耳朵经济”“声”气蓬勃地发展,无论是泛播客平台还是分众化播客平台都显示出巨大的发展潜力。泛播客与分众化播客“殊途同归”的成功背后暗含着的是二者不同的运营模式,分析二者不同运营模式或可为播客平台差异化竞争提供一些参考。本文藉此分别选取了喜马拉雅与蜻蜓FM作为泛播客与分众化播客的代表案例,分析其在内容运营模式、分发模式、盈利模式等方面的差异,并分析其共有困境与未来发展路径。With the vigorous development of “ear economy”, both general podcasting platforms and niche podcasting platforms have shown great potential for development. Behind the success of general podcasting and niche podcasting, different operation modes are implied, and analyzing the different operation modes of the two may provide some references for the differentiated competition of podcasting platforms. In this paper, Himalaya and Dragonfly FM are selected as the representative cases of pan-podcasting and niche podcasting to analyze their differences in content operation mode, distribution mode, profit model, etc., and analyze their common difficulties and future development paths.
文摘在不增加设备体积重量以及提高发射功率的前提下,为满足高码率遥测数据传输的需求,现有的脉冲编码调制-频调(Pulse Code Modulation Frequency Modulation, PCM-FM)遥测系统广泛使用多符号检测(Multiple Symbol Detection, MSD)算法和Turbo乘积码(TPC)技术。调制指数是PCM-FM遥测系统中的重要参数之一,对系统带宽和误码率有重要影响。本文分析了MSD多符号检测算法原理,通过计算互相关系数及Matlab仿真,分析了调制指数大小对带宽和误码率的影响,指出将调制指数设置为0.715较为合适;分析了调制指数偏差对信噪比损耗的影响,利用MSD算法的相位网格图分析了调制指数偏差对误码和码同步的影响,指出随机数据比连“0”或连“1”数据具有更好的容忍能力。
文摘目的:探讨胎盘生长因子(placental growth factor,PLGF)、可溶性fms样酪氨酸激酶-1(soluble fms-like tyrosine kinase-1,SFLT-1)和糖基化纤连蛋白(glycosylated fibronectin,GLYFN)检测对子痫前期的预测价值。方法:选择在无锡市妇幼保健院就诊的188例孕妇,分154例正常孕妇(对照组)和34例子痫前期患者(子痫组),应用免疫荧光法分别检测其在孕16~18周血清中PLGF、SFLT-1和GLYFN的浓度,比较子痫前期组和对照组各标志物的水平,并使用受试者操作特征曲线(receiver operating characteristic,ROC)对3种标志物的预测价值进行效能评估。结果:在妊娠中期,子痫前期组血清PLGF浓度低于对照组,SFLT-1及GLYFN浓度均高于对照组,3种标志物的差异均有统计学意义(3指标P=0.000)。95%置信区间的ROC曲线下面积(areas under the ROC curve,AUC)为,PLGF为0.941(0.907~0.974),SFLT-1为0.881(0.800~0.962),GLYFN为0.951(0.918~0.985),联合指标SFLT-1和GLYFN、3项指标联合检测在ROC曲线下面积(areas under the ROC curve,AUC)分别为0.968、0.986。结论:PLGF、SFLT-1、GLYFN 3种标志物水平在对照组和子痫前期组均存在明显差异,对子痫前期的发病具有一定的预测价值,SFLT-1联合PLGF、SFLT-1联合GLYFN、3项指标联合检测对子痫前期的预测价值高于任一单项指标。
文摘Chaos-based encryption schemes have been studied extensively, while the security analysis methods for them are still problems to be resolved. Based on the periodic orbit theory, this paper proposes a novel security analysis method. The periodic orbits theory indicates that the fundamental frequency of the spiraling orbits is the natural frequency of associated linearized system, which is decided by the parameters of the chaotic system. Thus, it is possible to recover the plaintext of secure communication systems based on chaotic shift keying by getting the average time on the spiraling orbits. Analysis and simulation results show that the security analysis method can break chaos shift keying secure communication systems, which use the parameters as keys.
文摘With the massive increase of wirelessly connected devices and the rapid development of the Internet, information is transmitted more and more frequently. Since the information transmissions over these networks are greatly threatened not only by the imperfection of channels but also by the potential attackers or eavesdroppers, security and reliability become some of the crucial requirements for our future networks. Due to the complex dynamic behavior, ergodicity, wide spectrum and sensitivity to initial values, chaos signals show most required attributes of good cryptosystems and great potentials in optical fiber communications for desirable spatial accuracy and distance. In this context, it has become imperative to investigate and apply chaos theories to solve emerging secure communication problems in various networks. This includes leveraging chaos systems and signals to address a wide range of secure communication challenges in optical fiber communications, chaos cipher, image encryption, etc.
