CDMA移动通信中的判决反馈多用户信号检测器

本文推导了一种具有线性计算复杂度的同步ＤＳ—ＣＤＭＡ系统多用户检测算法，由此形成的判决反馈检测器在性能上优于解相关检测器，与两级多用户检测器的性能相当，而实现起来则更为简单。数值结果表明，当接收到的干扰信号能量比有用信号能量高４ｄＢ以上时，判决反馈检测器的性能将接近单用户系统的性能，因而该检测器可有效地克服ＣＤＭＡ移动通信中的远近影响。     

Cryptomining Malware Detection Based on Edge Computing-Oriented Multi-Modal Features Deep Learning

In recent years, with the increase in the price of cryptocurrencies, the number of malicious cryptomining software has increased significantly. With their powerful spreading ability, cryptomining malware can unknowingly occupy our resources, harm our interests, and damage more legitimate assets. However, although current traditional rule-based malware detection methods have a low false alarm rate, they have a relatively low detection rate when faced with a large volume of emerging malware. Even ...     

Effect of substrate cooling on the epitaxial growth of Ni-based single-crystal superalloy fabricated by direct energy deposition

The columnar-to-equiaxed transition(CET)or the formation of stray grains in the laser melting deposition is the least desirable for the repair of single-crystal blades.In this work,the forced water-cooling was conducted on a single-crystal Rene N5 substrate during the direct energy deposition(DED).The single track remelting,one-layer,two-layer,and eight-layer depositions were investigated to explore the grain growth mechanism.The solidification conditions of the DED process,including temperature field,temperature gradient,and solidification speed,were numerically analyzed by a finite element model.The single-track remelting results showed that the fraction of columnar crystal regions increases from55.81%in the air-cooled sample to 77.14%in the water-cooled one.The single-track deposits of one-and two-layer have the same trend,where the proportion of columnar crystal height was higher under the forced water-cooled condition.The electron backscattered diffraction(EBSD)grain-structure maps of an eight-layer deposit show that the epitaxial growth height increases from 1 mm in the air-cooling sample to 1.5 mm in the water-cooling one.The numerical results showed that the tempe rature gradient in[0011 direction was significantly increased by using forced water-cooling.In conclusion,the in-situ substrate cooling can become a potential method to promote epitaxial growth during DED via the influence on CET occurrence.     

基于几何变形的大数据安全隐私保护方法

隐私保护已经成为大数据安全的重要研究内容之一。在分析了影响大数据安全隐私三个方面的基础上,提出了一种基于几何变形的大数据安全隐私保护方法。该方法从数据源的角度出发,使用几何变形的方法对数据进行干扰,使得数据聚类算法失效或分析得出错误的结果,从而达到大数据安全隐私保护的目的。在实际使用中,该方法效果良好。     

电力市场条件下的UPFC安装地点的综合定量化评价研究

电力市场的运营在给电力系统和社会带来巨大经济效益的同时,也对电力系统稳定运行提出了更高的要求。UPFC是解决电力系统稳定运行的有效技术之一。在考虑到UPFC安装后紧急控制有效程度,本文提出了评价UPFC安装地点的效果指标;同时,提出了稳态潮流控制下的UPFC安装地点评价指标;在此基础上,分析了在电力市场下的UPFC安装...     

矢量控制感应电动机H∞磁通观测器研究

转矩环和磁通环的解耦控制是矢量控制性能的保证,而解耦控制的精度取决于磁通观测器定向于电机实际磁通的精度.本文在分析电机参数不确定性的基础上,建立了考虑铁损的感应电动机全阶H∞磁通观测器.考虑磁通变化并采用增益规划控制设计线性时变系统的综合观测器,推导出不确定性与观测器误差的传递函数,通过配置观测器的极点区域提高H∞磁通观测器的动态性能,求解线性矩阵不等式得到H∞磁通观测器的反馈阵.建立实验系统,通过改变电机磁通幅值与电流模型对比了两种观测器的鲁棒性.     

Command filter-based adaptive neural network controller design for uncertain nonsmooth nonlinear systems with output constraint

This paper investigates the command filter-based adaptive neural network tracking control problem for uncertain nonsmooth nonlinear systems. First, an integral barrier Lyapunov function is introduced to deal with the symmetric output constraint and make the output comply with prescribed restrictions. Second, by the Filippov's differential inclusion theory and approximation theorem, the considered nonsmooth nonlinear system is converted to an equivalent smooth nonlinear system. Third, the Levant's differentiator is used to deal with the “explosion of complexity” problem. An error compensation mechanism is established to attenuate the effect of the filtering error on control performance. Then, an adaptive neural network controller is set up by resorting to the backstepping technique. It is strictly mathematically proved that the tracking error can converge to an arbitrarily small neighborhood of the origin and all the signals in the closed-loop system are semi-globally uniformly ultimately bounded. Finally, a numerical example and an application example of the robotic manipulator system are provided to demonstrate the availability of the proposed control strategy.     

跨模态表征与生成技术

多媒体数据持续呈现爆发式增长并显现出异源异构的特性,因此跨模态学习领域研究逐渐引起学术和工业界的关注。跨模态表征与生成是跨模态学习的两大核心基础问题。跨模态表征旨在利用多种模态之间的互补性剔除模态之间的冗余,从而获得更为有效的特征表示;跨模态生成则是基于模态之间的语义一致性,实现不同模态数据形式上的相互转换,有助于提高不同模态间的迁移能力。本文系统地分析了国际与国内近年来跨模态表征与生成领域的重要研究进展,包括传统跨模态表征学习、多模态大模型表示学习、图像到文本的跨模态转换和跨模态图像生成。其中,传统跨模态表征学习探讨了跨模态统一表征和跨模态协同表征,多模态大模型表示学习探讨了基于Transformer的模型研究,图像到文本的跨模态转换探讨了图像视频的语义描述、视频字幕语义分析和视觉问答等领域的发展,跨模态图像生成从不同模态信息的跨模态联合表示方法、图像的跨模态生成技术和基于预训练的特定域图像生成阐述了跨模态生成方面的进展。本文详细综述了上述各个子领域研究的挑战性,对比了国内外研究方面的进展情况,梳理了发展脉络和学术研究的前沿动态。最后,根据上述分析展望了跨模态表征与生成的发展趋势和突破口。     

亚微米TATB除酸方法比较

分别采用超声波震荡、加热下介质处理、稀碱处理等方法研究亚微米超细TATB夹杂酸的脱除.结果表明,超声波震荡法不利于亚微米TATB晶间酸的去除,有利于防止超细TATB粒子聚集;稀碱处理法能迅速降低细化料液的酸值,但仍不能有效去除晶体间夹杂酸,且处理后超细TATB样品灰分含量高;加热条件下有利于去除亚微米TATB晶间酸,却会造成亚微米TATB粒子团聚;以DMSO/水为介质,在加热条件下处理亚微米超细TATB样品,可控制pH值和粒度在许可范围.     

岩石龟裂系数法在火山岩裂缝储集层预测中的应用

 本文针对辽河东部凹陷油燕沟中生界火山岩的具体特征，采用纵波波速的比值——“龟裂系数”裂缝分析法［1,2,3］，研究了火山岩裂隙发育程度。综合龟裂系数裂缝分析及其他方法发现，该区中生界火山岩有效储集层的测井相特征主要表现为低密度、低中子、高声波时差和高伽马值等特征。此法的关键在于根据不同火山岩的岩性，选用合适的岩石骨架参数，在此基础上利用测井约束地震反演计算火山岩的层速度，进而计算出龟裂系数，然后根据已钻至火山岩井孔的测井相特征编制出火山岩预测厚度图。