Non-coherent sequence detection scheme for satellite-based automatic identification system

The satellite-based automatic identification system (AIS) receiver has to encounter the frequency offset caused by the Doppler effect and the oscillator instability. This paper proposes a non-coherent sequence detection scheme for the satellite-based AIS signal transmitted over the white Gaussian noise channel. Based on the maximum likelihood estimation and a Viterbi decoder, the proposed scheme is capable of tolerating a frequency offset up to 5% of the symbol rate. The complexity of the proposed scheme is reduced by the state-complexity reduction, which is based on per-survivor processing. Simulation results prove that the proposed non-coherent sequence detection scheme has high robustness to frequency offset compared to the relative scheme when messages collision exists.

Combined iterative cross-correlation demodulation scheme for mixing space borne automatic identification system signals

Aiming at the potential presence of mixing automatic identification system(AIS) signals,a new demodulation scheme was proposed for separating other interfering signals in satellite systems.The combined iterative cross-correlation demodulation scheme,referred to as CICCD,yielded a set of single short signals based on the prior information of AIS,after the frequency,code rate and modulation index were estimated.It demodulates the corresponding short codes according to the maximum peak of cross-correlation,which is simple and easy to implement.Numerical simulations show that the bit error rate of proposed algorithm improves by about 40% compared with existing ones,and about 3 dB beyond the standard AIS receiver.In addition,the proposed demodulation scheme shows the satisfying performance and engineering value in mixing AIS environment and can also perform well in low signal-to-noise conditions.

A New D-optimal Design Scheme for the Identification of Cubic Polynomials

In this paper, the limitations of the single cube D-optimal design scheme is studied, and a double cube D-optimal design scheme is suggested in order to overcome the limitations. For a sort of incomplete cubic polynomials, the test design of the identification is developed with this new scheme, and the comparation with the single cube scheme is also given. This scheme is shown to be perfectly suitable for the optimal identification of the complete cubic polynomials.

沉积岩中黏土矿物产状与鉴别特征

沉积岩中粘土矿物类型、含量和产状是控制储层质量、开发决策的关键参数,影响孔隙结构、孔隙度、渗透率和含水饱和度等储层特征,也直接或间接地影响油气开发的全过程,使得黏土矿物成为石油勘探开发研究中的重要对象。基于上述问题,结合当前不同学者对黏土矿物的产状的分类方案,文章基于偏光显微镜与扫描电子显微镜等,对粘土矿物产状与类型开展系统鉴别,考虑成因、孔隙度、粘土类型、粘土赋存形式等为因素,分析沉积岩中不同类型的黏土矿物产状和鉴别特征,形成不同粘土矿物鉴别的规范性图版和识别标志,对沉积粘土矿物分类形成一个科学性、适用性、完整性的分类格架,对定量定性评价粘土具有实际价值,有利于应用和交流。

一种高效的基于Fiat-Shamir认证协议的陷门哈希函数(英文)

陷门哈希函数在2000年由Krawczyk和Rabin正式描述.它是一种带有陷门密钥的哈希函数.陷门密钥的作用在于寻找函数的"碰撞".陷门哈希函数是构造变色龙签名协议和在线/离线签名协议的关键构件.现有的陷门哈希函数在计算函数值或者在寻找碰撞的运算中,均为指数运算复杂度.基于Fiat-Shamir认证协议,文章构造了一种新的陷门哈希函数.新的构造具有乘法运算复杂度,因此,大大提高了陷门哈希函数的效率.

一种轨道交通客流OD精准化辨识算法

特大城市的轨道交通承载着城市的交通运输骨干任务,积累了蕴含着乘客出行时空关系、出行规律及出行习惯等的客流票卡数据,具有较高的实践指导价值。首先,设计了轨道交通AFC数据预处理方法,构建了轨道交通客流刚性需求筛选算法;其次,改进FP-Tree算法并用于挖掘刚性需求客流OD,得出精准化的乘客进出站频繁项集;最后,构建基于换乘客流路径选择模型的客流换乘OD挖掘算法,将客流换乘OD转化为线路OD,精准化挖掘客流OD需求,研究成果可为轨道交通市郊线路快车停站方案的制定提供支持和决策指导。

Evil-hunter: a novel web shell detection system based on scoring scheme

In order to detect web shells that hackers inject into web servers by exploiting system vulnerabilities or web page open sources, a novel web shell detection system based on the scoring scheme is proposed, named Evil-hunter. First, a large set of malicious function samples normally used in web shells are collected from various sources on the Internet and security forums. Secondly, according to the danger level and the frequency of using these malicious functions in the web shells as well as in legal web applications, an assigning score strategy for each malicious sample is devised. Then, the appropriate score threshold value for each sample is obtained from the results of a statistical analysis. Finally, based on the threshold value, a simple algorithm is presented to identify files that contain web shells in web applications. The experimental results show that compared with other approaches, Evil-hunter can identify web shells more efficiently and accurately.

三端差动保护方案在电力系统故障快速识别中的性能评估与改进

随着电力系统的不断延伸与发展,故障快速识别和隔离变得尤为重要。三端差动保护方案作为一种重要的保护策略,在电力系统故障识别中发挥着关键作用。文章介绍了三端差动保护方案的基本原理,对其在故障快速识别中的性能进行了评估,包括故障识别速度、准确率和抗干扰能力。并在此基础上提出了一系列改进措施,如引入先进的信号处理技术、优化保护算法、加强通信系统建设以及完善故障录波功能,以提升三端差动保护方案在电力系统中的应用效果。

Analysis of identifiers in IoT platforms

The Internet of Things(IoT)provides new opportunities for different IoT platforms connecting various devices together.The need to identify those devices is the foremost important to perform any kind of operation.Many organizations and standard bodies that provide specifications and frameworks for the IoT currently have their own identification mechanisms.Some existing industrial identification mechanisms can also be used in the IoT.There is no common Identification Scheme(IS)for the IoT as yet,because of the political and commercial differences amongst the standard bodies.The unavailability of a unified IS method makes the inter-working among IoT platforms challenging.This paper analyses and compares ISs used by several selected IoT platforms.This work will help in understanding the need for a common identification mechanism to provide inter-working among different IoT platforms.

海上岸电平台消防设计实例

国内近海海域的海上石油天然气生产平台由传统的自发电转由陆地电网(岸电)供电,为海上油气平台供电的岸电平台逐渐成为国内近海海域新兴的海上油气生产设施类型。岸电平台与传统油气生产平台在总体布局、火灾风险等级、可燃物种类等各方面存在很大差异,传统油气生产平台的消防保护原则不再适用于岸电平台。以渤海某岸电平台为例,讨论了岸电平台的火灾风险识别、消防设计原则、消防设计方案,对岸电平台消防设计技术进行探讨。

新城金矿深部斜坡道围岩稳定性分析与控制技术

随着浅部资源的枯竭,我国金属矿石开采逐步进入深部阶段。为探索金属矿深部巷道围岩稳定性分析和控制技术,以新城金矿深部斜坡道围岩支护技术为研究背景,前期通过现场工程地质调查获取围岩的结构面信息,采用Dips对结构面信息进行统计分析。在现场进行岩石取样后,对样品进行室内岩石力学试验,最终获得了岩石的物理力学参数。采用Q分级、RMR分级及GSI对岩体进行质量分级,采用Roc Lab对岩体的物理力学参数进行估算。应用Unwedge对巷道的潜在楔形体进行了识别,发现巷道顶板存在大型楔形体,且存在极大冒落风险,并基于岩体质量分级结果和分级支护图表,确定采用“树脂锚杆+锚索+金属网+双筋条+钢筋梁+喷射混凝土”对该区域进行支护。最终应用Phase2和Unwedge对巷道支护效果进行分析。结果表明,采用该支护方式后围岩的塑性区范围和位移量都有所降低,顶板楔形体的安全系数也提高到了35.897,冒落风险得到了有效的控制。本研究证明该支护方式可有效保证巷道围岩的稳定,也可为类似矿山的巷道围岩支护提供指导。

Application of Morphological Max-Lifting Scheme for Identification of Induction Motor Stator Inter-turn Short Circuit

The harmonic components of stator winding current in induction motor will change under the condition of stator inter-turn short circuit.According to these characteristics,in this paper,a novel technique based on morphological maxlifting scheme is proposed for identification of induction motor stator inter-turn short circuit.A max-lifting scheme is applied to process stator winding currents to extract these characteristics.An indicator,r,is computed to identify the short circuit.The transient model of induction motor is employed to simulate oneturn to six-turn stator inter-turn short circuits in an induction motor.Extensive simulation work has been conducted under normal conditions,abnormal conditions(voltage imbalance and varying load),stator inter-turn short circuit conditions,and conditions of any combinations of the above.The results have shown that the scheme proposed in this paper has a high identification rate for induction motor stator inter-turn short circuit.

电力系统快速切负荷方案降损节能分析

由于传统方法在分析电力系统快速切负荷方案降损节能中,存在网络损耗高等问题。为此,对电力系统快速切负荷方案降损节能进行分析。基于PQ分解法的方程组,简化电力系统快速切负荷参数分解方程,计算得到电力系统快速切负荷方案的潮流,结合电压计算和负荷计算,设计电力系统快速切负荷方案降损节能算法,实现电力系统快速切负荷方案的降损节能。实验结果表明,文中方法可以降低电力系统快速切负荷方案降损节能的网络损耗,具有更好的性能。

Efficient and provably secure identification scheme without random oracles

The research on the identification scheme is an important and active area in computer and communication security. A series of identification schemes were proposed to improve the efficiency and security of the protocols by various methods. Based on the hardness assumption of the discrete logarithm problem in a gap Diffie-Hellman group and the difficulty of the collusion attack algorithm with k traitors, an efficient identification scheme is presented. Without random oracle models, the proposed scheme is then proved secure against impersonation and reset attacks in both concurrent and reset attack setting. Since the proposed scheme is simple, memory-saving, computation-efficient, and perfectly-secure, it is well suitable for use in smart cards.

一次高空落物事件的调查及启示

高空落物事件多发生在钻修井的钻台面上,常导致钻台作业人员的伤亡,故钻台面上的设备在设计、制造及使用过程中,需考虑落物的风险。对1起钻台面高空落物事件进行了调查,发现了该高空设备在设计、制造、使用过程中的缺陷。提出提高风险意识及准确的风险识别是减少事故发生的两个重要基础,完善的落物管理系统需覆盖设备的设计、制造、使用全生命周期,从而避免落物事故的发生。

System identification with binary-valued observations under both denial-of-service attacks and data tampering attacks:defense scheme and its optimality

In this paper,we investigate the defense problem against the joint attacks of denial-of-service attacks and data tampering attacks in the framework of system identification with binary-valued observations.By estimating the key parameters of the joint attack and compensating them in the identification algorithm,a compensation-oriented defense scheme is proposed.Then the identification algorithm of system parameter is designed and is further proved to be consistent.The asymptotic normality of the algorithm is obtained,and on this basis,we propose the optimal defense scheme.Furthermore,the implementation of the optimal defense scheme is discussed.Finally,a simulation example is presented to verify the effectiveness of the main results.

结构动态载荷识别的精细逐步积分法

对比例阻尼系统给出了基于精细逐步积分法的动态载荷识别方法。首先将系统进行模态坐标变换得到无耦合运动方程 ,然后应用精细逐步积分法构造一种高效精确的载荷识别公式 ,再由量测到的结构动态响应求出动态力的时间历程。

量子通信网络中的身份认证方案

提出了一种基于Greenberger Horne Zeilinger(GHZ)三重态量子相干性的身份认证方案,该方案可以应用在量子通信网络当中.

运用灰色关联法进行灌区运行状况综合评价

利用层次分析法和信息熵理论相结合进行评价指标权重的确定,并利用灰色关联法对灌区运行状况进行评价。通过对湖北省大型灌区现状水平的评价,根据各灌区关联度的大小对灌区进行排序与分类;同时根据评价指标的关联度,可知各指标对灌区运行状况综合评价的重要性。最后通过灰色关联法与近似理想点排序法对各灌区的评价结果进行比较,可知这二种评价方法对各灌区排序结果基本相一致,说明利用灰色关联法对灌区运行状况进行综合评价是一种有效、简便的评价方法。

(t,n)阈方案的欺诈识别

（ｔ，ｎ）阈方案中的欺诈识别是一个很重要的问题．文中提出了一种有效的基于平方剩余的欺诈识别方案，攻击时的难度相当于分解两个大素数的乘积的难度．它无须使用单向哈希函数，并且对公共参数的完整性给予保证，可以阻止阴谋者起诉陷害某个特殊的成员．它很容易扩展到分享多个秘密的情况．它所需的通信量较Ｃｈａｎｇ－Ｈｗａｎｇ方案小．