Recognition of multi-carrier OFDM and single-carrier with alpha-stable distribution noise

In order to identify the multi-carrier orthogonal frequency division multiplexing(OFDM) and the single-carrier signal in the non-Gaussian noise environment, different features of the two signals are analyzed in terms of five parameters: generalized normalized fourth-order cumulant, the maximum value of the instantaneous amplitude power spectral density, absolute standard deviation of instantaneous phase on the section with weak signals, and position and numbers of the generalized cyclic spectrum's peak. The recognition method of the multi-carrier OFDM and single-carrier signal is proposed in the environment with alpha-stable distribution noise. Simulation results show that the recognition rate of the multi-carrier OFDM can reach 100% when the mixed signal to noise ratio(MSNR) is greater than-5 dB and the recognition rate can reach 90% for the single-carrier when the MSNR is greater than 2 dB.

Securing color image transmission using compression-encryption model with dynamic key generator and efficient symmetric key distribution

There are a few issues related to the existing symmetric encryption models for color image data,such as the key generation and distribution problems.In this paper,we propose a compression-encryption model to solve these problems.This model consists of three processes.The first process is the dynamic symmetric key generation.The second one is the compression process,which is followed by encryption using keystreams and S-Boxes that are generated using a chaotic logistic map.The last process is the symmetric key distribution.The symmetric key is encrypted twice using Rivest-Shamir-Adleman(RSA)to provide both authentication and confidentiality.Then,it is inserted into the cipher image using the End of File(EoF)method.The evaluation shows that the symmetric key generator model can produce a random and dynamic symmetric key.Hence,the image data is safe from ciphertext-only attacks.This model is fast and able to withstand entropy attacks,statistical attacks,differential attacks,and brute-force attacks.

Prediction of Symmetrical and Asymmetrical of Diurnal Global Solar Irradiance Distribution—New Approach

A simple formula to predict the received global solar irradiance q(t), W/m2 for clear days is suggested on pure theoretical basis. It is expressed in terms of the length of the local day time td which is well defined in literatures on meteorological basis. The introduced distribution is also a function of the maximum value of the daily received irradiance qmax. which in turn is expressed in term of the solar constant. This renders the trial to be a closed system. Thus the obtained distribution is not a semi empirical one. Both cases of symmetrical and asymmetrical distributions for q(t) are considered. For its simplicity it can be easily integrated along the length of the day to get the daily totals of solar energy received by unit horizontal area. This is important for practical applications. Comparison between computed according to the present model and published experimental meteorological data in Barcelona (Spain), Hong Kong (China), Jeddah and Makkah (Saudi Arabia) is given as illustrative examples. Better fitting relative to the published trials for the same locations are obtained. The introduced model itself gives good fitting for the intermediate intervals points of the local day time which is the more effective region. The estimated relative error is 12% for Hong Kong, and it is 7% for Barcelona, Jeddah and Makah.

Six-State Symmetric Quantum Key Distribution Protocol

We propose and demonstrate an optical implementation of a quantum key distribution protocol, which uses three-non-orthogonal states and six states in total. The proposed scheme improves the protocol that is proposed by Phoenix, Barnett and Chefles [J. Mod. Opt. 47, 507 (2000)]. An additional feature, which we introduce in our scheme, is that we add another detection set;where each detection set has three non-orthogonal states. The inclusion of an additional detection set leads to improved symmetry, increased eavesdropper detection and higher security margin for our protocol.

Basic Functions for Computational Implementation of the Box-Cox Symmetric Class of Distributions

A class of distributions called Box-Cox symmetric was proposed for random variables with asymmetric distributions. This class allows through its structure an interpretation of the parameters in terms of quantiles (in particular, the median), relative dispersion and skewness. This study presents the initial results of the computational development of basic functions of each of the distributions that make up the Box-Cox symmetric class. Four functions have been developed to compose a routine in software R up to now. These functions are related to random numbers generation, probability density function, cumulative distribution function, and quantile function associated to a given probability. Examples of implemented functions were presented. The gamlss routine was used to check the performance of developed functions.

Quantum key distribution series network protocol with M-classical Bobs

Secure key distribution among classical parties is impossible both between two parties and in a network. In this paper, we present a quantum key distribution （QKD） protocol to distribute secure key bits among one quantum party and numerous classical parties who have no quantum capacity. We prove that our protocol is completely robust, i.e., any eavesdropping attack should be detected with nonzero probability. Our calculations show that our protocol may be secure against Eve＇s symmetrically individual attack.

Distribution of the Permian Monodiexodina in Karakorum and Kunlun and its Geological Significance

The Permian fusulinoidean genus Monodiexodina is widely distributed in east Tethys. The genus might be an important indicator for the northern margin of Gondwana in northwestern China, but this is disputed. Monodiexodina-bearing areas can be restored as in either northern or southern middle latitudes with a symmetrical distribution between a high latitudinal, cool/cold water climatic realm and a paleotropical, warm water realm. Permian strata bearing Monodiexodina in Karakorum, Muztag Pear, and Buka Daban Pear of the east Kunlun Mountains can be correlated with each other. Faunal analyses and the stratigraphical position of Monodiexodina-bearing strata indicate that both Karakorum, east Kunlun, and the Pamirs were formed in a cool temperate sea area of the northern hemisphere in middle latitudes during the Permian, rather than at the Gondwana margin.

Multinucleon transfer dynamics in nearly symmetric nuclear reactions

Within the framework of the dinuclear system model,the multinucleon transfer dynamics for nearly symmetric nuclear collisions has been investigated.The reaction mechanism in the systems of 198Pt+198Pt and 204Hg+198Pt was investigated at beam energies around the Coulomb barrier.It was found that the isotopic yields are enhanced with increased incident energy in the domain of proton-rich nuclides.However,the production on the neutron-rich side weakly depends on the energy.The angular distribution with the beam energy was also analyzed in the multinucleon transfer reactions.Projectile-like fragments were produced toward the forward emission with increasing incident energy.The target-like fragments manifested the opposite trend in the transfer reactions.

Some Properties of <i>CR</i>-Submanifolds of a Nearly Trans-Sasakian Manifold with a Semi Symmetric Non-Metric Connection

This paper deals with the study of CR-submanifolds of a nearly trans-Sasakian manifold with a semi symmetric non-metric connection. Nijenhuis tensor, integrability conditions for some distributions on CR-submanifolds of a nearly trans-Sasakian manifold with a semi symmetric non- metric connection are discussed.

ESMD Method for Frequency Distribution of Tank Surface Temperature under Wind Effect

Due to the poor understanding of the small-scale processes at the air-water interface, some lab experiments are done in a water tank by infrared techniques. With the help of ESMD method, the stochastic temperature sequences extracted from the infrared photographs are decomposed into several empirical modes of general periodic forms. The corresponding analyses on the modes reveal that, within certain limits, both spatial and temporal frequencies increase along the wind speed. As for the amplitudes, the existence of wind may result in fold increasing of their values. In addition, when the wind speed is added from 4 m/s to 5 m/s, both frequency and amplitude of the surface temperature decrease and it implies an enhanced mixing and a weakened temperature gradient under the force of wind blowing.

Asymptotic Properties of Estimators for Ornstein-Uhlenbeck Processes with Small Symmetricα-Stable Motions

The asymptotic behaviors for estimators of the drift parameters in the Ornstein-Uhlenbeck process driven by small symmetricα-stable motion are studied in this paper.Based on the discrete observations,the conditional least squares estimators(CLSEs)of all the parameters involved in the Ornstein–Uhlenbeck process are proposed.We establish the consistency and the asymptotic distributions of our estimators asεgoes to 0 and n goes to∞simultaneously.

7元旋转对称2-弹性函数的构造

基于旋转对称轨道的数对分布矩阵的性质,给出了所有7元旋转对称2-弹性函数的具体构造。结果表明,在F_(2)^(7)上有且仅有280个非线性旋转对称2-弹性函数。进一步地,对于任意的奇数k,在F_(2)^(7k)上至少有280个非线性旋转对称2-弹性函数。

配电变压器三相不平衡附加损耗量化分析

配电网变压器三相不平衡附加损耗的计算由于缺乏对铁耗等的全面分析而精度不高。考虑到损耗治理依赖于精确有效的损耗数据,故提出计及铁耗变化的配电变压器三相不平衡附加损耗计算方法。利用磁动势平衡方程式来分析励磁磁动势和主磁通的产生过程,以建立励磁电流与一、二次侧相电流的关系。根据配电变压器的绕组联结方式建立正序、负序和零序等值电路模型,给出三相不平衡下的附加损耗计算方法。仿真测试结果表明,与现有方法相比,所提附加损耗计算方法能够量化反映三相不平衡对变压器损耗产生的影响,在不同负荷率和不同励磁阻抗参数条件下均具有更低的计算误差。

一种包含组合范数惩罚项的波达方向稀疏估计方法

波达方向(Direction of Arrival,DOA)估计是阵列观测数据研究领域的一个基本问题.对于观测数据服从复椭球对称分布的应用场景,现有的方法多采用l1-范数惩罚项来实现信号波达方向的稀疏估计,其中的l1-范数惩罚项仅考虑信号的稀疏性而没有考虑信号的多样性,从而造成这些估计方法一般将弱信号(具有较低功率的信号)略去,可能无法准确地估计弱信号的波达方向.为解决这个问题,本文通过引入一个组合范数惩罚项构建了一个新的估计(模型)方法,其中的组合范数惩罚项是l1-范数惩罚项与l2-范数平方惩罚项的线性组合,其组合系数(惩罚参数)互不相关,l2-范数平方惩罚项则可以保留弱信号的多样性.然后,本文基于Majorization-Minimization(MM)算法设计了模型的求解算法,并证明该方法是收敛的.数值实验表明,相较于那些基于l1-惩罚项的估计方法,本方法具有更高的精度.

基于一次哈希签名和联盟链的密钥分发协议

在物联网环境中,为了确保通信数据的机密性和完整性,数据加密密钥的安全性尤为重要。密钥一般采用中心化的存储机制,当中心实体不可信时会造成密钥泄露的风险,因此在分发过程中需要保证密钥的完整性,但普通的签名方案往往较为复杂。针对密钥分发中心化及密钥分发算法复杂等问题,提出了一种基于一次哈希签名和联盟链的密钥分发协议。首先,利用轻量级的一次哈希签名进行用户注册和认证,同时,为了有效检测和防御使用一次哈希签名过程中可能出现的中间人攻击,协议中使用了Hyperledger Fabric联盟链存储签名凭证,用户可以从联盟链上获取签名凭证以供认证;然后,基于Hyperledger Fabric链和ElGamal密码体制设计了一个对称密钥分发方案;最后,从理论分析和Scyther形式化协议分析工具两个方面分析了密钥分发协议的安全性,结果表明该协议在保证密钥分发安全性的情况下,提高了密钥分发的效率。

逐步增加Ⅱ型截尾下Pareto分布形状参数的Bayes估计

基于逐步增加Ⅱ型截尾样本,首先得出Pareto分布形状参数的极大似然估计,考虑两个损失函数和形状参数的两个先验分布,得出该分布形状参数的4个Bayes估计。由数值模拟结果发现,上述四个Bayes估计值的均方误差均小于极大似然估计值,其中,当损失函数为二次损失函数,形状参数的先验分布为共轭先验分布时的Bayes估计的均方误差较小,估计效果更理想,且实例分析与数值模拟结果相符。其次在二次损失函数下,针对形状参数先验分布选取共轭先验分布,给出Pareto分布形状参数的多层Bayes估计和E-Bayes估计。

计及电压幅值检测延时及相位跳变的IIDG故障电流解析计算

逆变型分布式电源(inverter interfaced distributed generation,IIDG)的波动性、弱馈性及强受控性,使其在故障下具有与同步发电机不同的短路电流特性,对其进行准确解析是继电保护适应性分析与保护新原理研究的基础,具有重要意义。针对现有研究忽略电压幅值检测延时导致IIDG故障特性难以准确解析的问题,以新能源送出线路发生三相短路为例,综合考虑电压幅值检测延时以及相位跳变所引起锁相环动态响应特性的影响,对IIDG故障暂态过程进行精细化划分,分别针对故障暂态过程的2个阶段,建立了电压电流双环控制和电流环控制下的故障电流解析表达式,明确了电压检测延时与锁相环动态响应对IIDG故障电流暂态特性的影响机理。最后,基于Matlab/Simulink仿真平台,验证了所提故障电流解析计算模型的正确性。

INADMISSIBILITY OF THE USUAL ESTIMATOR FOR THE LOCATION PARAMETERS OF SPHERICALLY SYMMETRIC DISTRIBUTIONS

I. INTRODUCTIONIt is well-known that the usual estimator, the sample mean, for the mean of a multivariate normal distribution is inadmissible. After the improvement of the original proof, several concise proofs are proposed, referring to Anderson, for example.

局部对称算法在区块链分布式存储中的优化

提出一种局部对称算法,将区块链系统中的节点划分为多个节点子集,每个节点子集生成一个私钥对数据进行加密,将加密后的数据分布存储于节点子集的节点中。利用局部对称算法将哈希值和私钥分别设为全局秘密和局部秘密,用局部秘密对数据区块进行加密并将结果分布存储于节点子集的节点中,用基于中国剩余定理秘密共享的分布式存储方案对私钥和哈希值进行有效存储,达到降低存储成本和通信成本的目的.仿真结果表明,对比减存储算法和单节点故障算法,局部对称算法在区块链分布式存储中的存储成本和通信成本更低.

混氢天然气对流量计安装条件的适应性分析

目的 将氢气混入天然气中后会改变流体的性质和流动状态,从而影响流量计的计量准确度,采用ANSYS Fluent模拟弯头后混氢天然气的速度分布,分析现行的孔板流量计和超声流量计安装条件标准是否适用于混氢天然气管道。方法 模拟单90°弯头和双90°弯头后混氢天然气的速度场,分析现行标准中规定的流量计安装位置是否能使混氢天然气速度达到对称分布,从而说明是否需要延长现行标准中规定的弯头后流量计安装位置前直管段长度。结果 (1)在单90°弯头后44D和50D截面处,掺氢量(摩尔分数,下同)为10%~30%时,气体流速未恢复到对称速度分布;(2)在双90°弯头后44D截面和50D截面处,掺氢量为10%时,气体流速已恢复到对称速度分布,掺氢量为20%~30%时的流速未恢复到对称速度分布;(3)在双90°弯头后30D截面处,掺氢量为10%时的流速未恢复到对称速度分布。结论 (1)对于混氢天然气,应适当延长现行标准中规定的单弯头后流量计前直管段长度;(2)当掺氢量达到20%~30%时,应适当延长双弯头后流量计前直管段长度;(3)当掺氢量达到10%且孔板孔径比减小时,应适当延长孔板流量计前直管段长度。