Effects of Austenitising Conditions on the Microstructures and Mechanical Properties of Martensitic Steel with Dual Matrix Structure

A new high strength steel with dual matrix structure and exceptionally high toughness plus ductility have been produced by intermediate quenching of 0.22_wt% C microalloyed steel. The treatment consisted of initial austenitization and rapid quenching of the steel samples to achieve a fully martensitic state followed by annealing in the intercritical (α+γ) region of 730℃-810℃ for the period of 30, 60 and 90_minutes. These samples were subsequently quenched to obtain dual phase microstructure containing varying proportions of ferrite and martensite constituents. The mechanical properties of the samples were measured according to ASTM standard and their microstructures were analyzed by optical microscopy. The experimental results show that martensitic dual phase (MDP) steel samples developed within the intercritical temperature range of 770–790℃ revealed finer martensite and precipitate-free ferrite microstructure. The tensile and impact properties of the developed HMDP steels increased with intercritical annealing (ICA) temperatures, with an optimum properties obtained at 790℃ mainly due to finer microstructure of the constituent phases and absence of carbide precipitate that permit ease of dislocation flow. A further increase in the intercritical annealing temperature beyond 790℃ led to general decrease in the mechanical properties. This is attributed to the formation of coarse structure in this region. The results further show that with increasing intercritical treatment time from 30 to 90 minutes, the general mechanical properties of the MDP steels were found to increase except at the higher temperature of 810℃ which showed decreasing values. In general, the tensile strengths and ductility as well as the impact properties of the developed dual phase steel samples are greatly improved with the intercritical heat treatment investigated.

BANACH SPACES AND INEQUALITIES ASSOCIATED WITH NEW GENERALIZATION OF CESàRO MATRIX

Let the triangle matrix A^(ru)be a generalization of the Cesàro matrix and U∈{c_(0),c,l_(∞)}.In this study,we essentially deal with the space U(A^(ru))defined by the domain of A^(ru)in the space U and give the bases,and determine the Kothe-Toeplitz,generalized K?theToeplitz and bounded-duals of the space U(A^(ru)).We characterize the classes(l_(∞)(A^(ru)):l_(∞)),(l_(∞)(A^(ru)):c),(c(A^(ru)):c),and(U:V(A^(ru)))of infinite matrices,where V denotes any given sequence space.Additionally,we also present a Steinhaus type theorem.As an another result of this study,we investigate the l_(p)-norm of the matrix A^(ru)and as a result obtaining a generalized version of Hardy's inequality,and some inclusion relations.Moreover,we compute the norm of well-known operators on the matrix domain l_(p)(A^(ru)).

Three Phase Dual Input Direct Matrix Converter for Integration of Two AC Sources from Wind Turbines

This project proposes a novel dual-input matrix converter (DIMC) which is used to integrate the output of the wind energy to a power grid. The proposed matrix converter is developed based on the traditional indirect matrix converter under reverse power flow operation mode, but with its six-switch voltage source converter replaced by a nine-switch configuration followed by the current source inverter (CSI). Matrix electric power conversion topologies and their switch functions are flexible and are used for specific applications. With the additional three switches, the proposed DIMC can provide six input terminals, which make it possible to integrate two independent AC sources from two independent wind turbines into a single grid tied power electronics interface. Commanded currents can be extracted from the two input sources to the grid. The proposed PI control and modulation schemes guaranteed sinusoidal input and output waveforms as well as reduced THD. The simulation results are provided to validate the effectiveness of the proposed control and modulation schemes for the proposed converter.

Norms of Dual Complex Vectors and Dual Complex Matrices

In this paper,we investigate some properties of dual complex numbers,dual complex vectors,and dual complex matrices.First,based on the magnitude of the dual complex number,we study the Young inequality,the Hölder inequality,and the Minkowski inequality in the setting of dual complex numbers.Second,we define the p-norm of a dual complex vector,which is a nonnegative dual number,and show some related properties.Third,we study the properties of eigenvalues of unitary matrices and unitary triangulation of arbitrary dual complex matrices.In particular,we introduce the operator norm of dual complex matrices induced by the p-norm of dual complex vectors,and give expressions of three important operator norms of dual complex matrices.

对偶P-分解及偏序

文章应用对偶奇异值分解建立对偶复矩阵的P-分解,得到该分解的若干性质,应用该分解建立D-GL二元关系,并证明该二元关系是一类偏序。

加密域灰度半色调图像的可逆信息隐藏

文章提出一种针对半色调图像的可逆信息隐藏算法,鉴于半色调图像信息冗余少的缺点,在嵌入水印前将载体图像的像素复制到两个相同的图像中,人为增加冗余。通过使用校验子编码来改变图像中的像素,将水印嵌入到第一个载体图像中;通过位替换,将水印嵌入到第二个载体图像中,得到两个隐秘图像。在提取阶段,先通过汉明码的校验矩阵处理第一个隐秘图像获得水印信息,并与第二个隐秘图像中的像素进行位替换,便可恢复载体图像。本方案适用于可逆性至关重要的数据隐藏应用场景,如印刷打印领域。

HARTREE-FOCK赝势方法中DUAL基函数的级数展开

本文引入在Hartree-Fock赝势方法中可表为原子轨道的线性组合的一组DuaL基函数,证明了Hartree-Fock哈密顿矩阵可以展为近邻原子轨道的重叠积分的级数,在一级近似下,可以略去双粒子相互作用项。相应的哈密顿及态重叠的矩阵元具有较为简单的表示。并给出了NaCl中F心缺陷电子的计算结果。此方法可以普遍推广应用。

基于情感增强和语义依存的金融隐式情感分析模型

金融情感分析是一种判断金融文本的情感倾向性的技术,广泛应用于舆情分析和监管协调等方面。由于金融领域文本中包含隐式情感信息,难以根据情感特征直接判定情感极性。针对这一问题,提出一种基于情感增强和语义依存的金融隐式情感分析模型(FSED),以期提高分类的准确率。首先,采用FinBERT生成词向量,并输入到Bi-GRU提取上下文语义信息,通过嵌入积极和消极情感词向量构建两极注意力机制,用于分别提取2种语境下的情感特征向量;然后,根据文本的语义依存图建立依存关系和关系类型矩阵,结合2种矩阵和top-k策略构建选择注意力矩阵,再输入到图卷积网络来提取文本的语义依存特征;最后,融合情感增强和语义依存的特征,并使用平均池化和最大池化层对特征进行压缩,经全连接层和Softmax获得分类结果。实验结果表明,相较于A-GCN,FSED可以提升金融领域隐式情感分析的准确率。

基于双核控制器的有轨电车制动信号切换智能控制方法

[目的]由于有轨电车制动信号切换需要充分考虑交通路口间距以及交通流量实际情况,导致控制效果难以得到保障,为此,提出基于双核控制器的有轨电车制动信号切换智能控制方法。[方法]将STMicroe1ectronics STM 32双核多协议无线微控制器作为具体的中心装置,在DMA(直接内存访问)控制器的3个通道分别设置了3个不同的动作,同时以时间步t为基准,对制动信号的相位控制调整矩阵进行多维设置,构建制动信号动作空间。以当前有轨电车信号的状态为基础,从动作价值的角度定义切换制动信号的确定性梯度参数,利用STM32无线MCU(微控制单元)对反馈动作的价值损失与反馈动作的价值奖励进行训练,计算切换制动信号的确定性梯度参数,作为制动信号切换控制基准。搭建仿真测试环境,设置对照组进行对比测试,验证控制方法的性能。[结果及结论]基于双核控制器的有轨电车制动信号切换智能控制方法控制延迟始终稳定在0.4 s以内,制动信号(红灯)的实际执行时长与设置时长的偏差稳定在0.04 s以内,等待队列长度始终低于对照组,在实时性、准确性及可靠性等方面优于对照组,能提高有轨电车的运行效率和安全性。

基于参考电压修正的双级矩阵变换器Delta-Sigma调制

Delta-Sigma调制(DSM)可在无需随机过程统计特性和复杂谐波理论分析的基础上,依托其过采样特性实现电力电子变换器变频调制。双级矩阵变换器(TSMC)作为一种理想的“全硅”交-交变换器,若能够将DSM引入TSMC,可进一步优化其电磁干扰(EMI)水平和运行效率,但TSMC的直流链电压波动问题导致TSMC-DSM策略难以直接实现。针对TSMC-DSM实现问题,该文提出一种基于参考电压修正的DSM策略。在所提方法中,通过解析TSMC整流级调制过程,将逆变级参考电压按照整流级矢量作用顺序进行修正,并依次获得各扇区参考电压修正系数。最后,在两相坐标系下分别构建两个DSM调制器,并将修正后的逆变级电压参考值引入DSM调制器以实现高性能TSMC-DSM策略。实验结果表明,所提策略能够对输出电压、电流频谱进行合理整形以减少系统对外部的电磁干扰,同时具备优良的电压传输比和动态调制性能。

ALMOST CONVERGENCE AND DOUBLE SEQUENTIAL BAND MATRIX

The class f of almost convergent sequences was introduced by G.G. Lorentz, using the idea of the Banach limits [A contribution to the theory of divergent sequences, Acta Math. 80（1948）, 167-190]. Let fo（B） and f（B） be the domain of the double sequential band matrix B（r, s） in the sequence spaces f0 and f. In this article, the β- and γ-duals of the space f（B） are determined. Additionally, we give some inclusion theorems concerning with the spaces f0（B） and f（β）. Moreover, the classes （f（B） ： μ） and （μ： f（B）） of infinite matrices are characterized, and the characterizations of some other classes are also given as an application of those main results, where μ is an arbitrary sequence space.

On a Generalized Matrix Algebra over Frobenius Algebra

Let A be a Frobenius k-algebra. The matrix algebra R =(■) is called a generalized matrix algebra over a Frobenius algebra A. In this paper we show that R is also a Frobenius algebra.

Dual Treatment Strategy by Venous Ulcers: Pilot Study to Dual-Frequency Ultrasound Application

We propose a new dual treatment strategy by venous ulcer, consisting in simultaneous modulation of matrix metalloproteinases (MMPs) and heat shock proteins (HSPs) in the wound. One treatment method which can efficiently modulate both these substances is based on the application of dual-frequency ultrasound (LDM). This strategy was checked in a pilot study on 10 patients with chronic venous ulcers and demonstrated excellent healing rate.

基于暂态录波与多元状态估计的阀冷系统故障预警及识别

阀冷系统是直流输电工程的重要设备之一,提高其故障预警及识别水平具有重要实用价值。利用主泵周期切换触发的双频暂态录波数据,提取系统在切泵扰动下的特征量,从而提高运算效率;提出基于聚类算法和切换工况相结合的动态过程记忆矩阵构建方法,根据多元状态估计得出估计向量,计算估计向量与观测向量的余弦相似度,采用3σ离群检测值作为预警阈值,然后根据预警观测向量与切换工况的耦合程度,以及3种故障类型对误差的贡献率实现故障识别。最后,通过案例分析验证了所提方法的有效性。

Adaptive neural network control for coordinated motion of a dual-arm space robot system with uncertain parameters

Control of coordinated motion between the base attitude and the arm joints of a free-floating dual-arm space robot with uncertain parameters is discussed. By combining the relation of system linear momentum conversation with the Lagrangian approach, the dynamic equation of a robot is established. Based on the above results, the free-floating dual-arm space robot system is modeled with RBF neural networks, the GL matrix and its product operator. With all uncertain inertial system parameters, an adaptive RBF neural network control scheme is developed for coordinated motion between the base attitude and the arm joints. The proposed scheme does not need linear parameterization of the dynamic equation of the system and any accurate prior-knowledge of the actual inertial parameters. Also it does not need to train the neural network offline so that it would present real-time and online applications. A planar free-floating dual-arm space robot is simulated to show feasibility of the proposed scheme.

长方对偶矩阵的加权对偶群逆的存在性与表示

本文研究了长方对偶矩阵的加权对偶群逆的存在性与表示问题.利用矩阵的秩和分块表示等给出了长方对偶矩阵的加权对偶群逆存在的若干充分必要条件,并在加权对偶群逆存在的情形下给出了其表达式,推广了对偶群逆的相关结论.通过数值例子说明了加权对偶群逆存在时的计算方法.

基于复功率分布矩阵的电力系统碳流追踪方法

随着“双碳”目标的提出,电力系统降碳转型迫在眉睫,为掌握电网运行过程中碳流动情况以及电网碳分布情况,提出了一种基于复功率分布矩阵的电力系统碳流追踪方法。首先以电力系统精准潮流结果为基础,构造电力系统复功率分布矩阵,得到有损网络中发电机组所发出的功率在各个节点的分配情况;然后根据不同的发电机组类型与长期运行数据,构建火电机组碳排放模型;最后依据该模型得到的电源侧碳排放数据和碳流与潮流的换算关系,分析负荷、支路和网损三者的碳排放分布情况并基于有功-无功耦合关系对网损的碳排放进行划分,实现电力系统碳流的准确追踪。采用该碳流追踪模型在IEEE 14,IEEE 30节点系统进行测试,测试结果表明,该模型可精准计算电力系统实时的碳排放分布情况,计算各负荷、支路及网损的碳排放,明确各支路无功功率对碳排放的影响,可为用户侧碳排放责任分摊及碳减排措施制定提供指导。

基于概念复合的对偶三支概念格及其概念约简

三支概念格通过正负算子相结合,既表示出了共同拥有的信息,又表示出了共同不拥有的信息,是对经典概念格的扩展。但在处理一些实际问题时,人们也会从反向出发,考虑集合的补集可能不拥有的信息和可能拥有的信息,对偶三支概念格应运而生。文中提出了一种基于形式背景的对偶概念及其补背景中对偶概念的复合来构造对偶三支概念格的方法,经验证,通过概念复合方法得到的对偶三支概念与通过对偶三支算子得到的概念相同。进一步讨论了基于可辨识矩阵求解对偶三支概念格的属性约简方法,并借助此思想,给出了基于概念可辨识矩阵的对偶三支概念约简方法。

免热处理(TiB_(2)+ZrB_(2))/Al-Mg-Mn基复合材料的显微组织与力学性能

基于交通、航空航天等领域高强韧精密复杂零件免热处理的需求,采用原位生成反应法制备了(TiB_(2)+ZrB_(2))/Al-Mg-Mn基复合材料,对比研究了重力铸造和挤压铸造制备的(TiB_(2)+ZrB_(2))/Al-Mg-Mn基复合材料的微观组织和力学性能。结果表明:原位生成反应法制备的复合材料中生成了大量纳米级的TiB_(2)和ZrB_(2)颗粒。拉伸实验结果表明,挤压铸造复合材料试样的抗拉强度、屈服强度和伸长率分别为296 MPa、185 MPa和12.2%,这些参数比重力铸造成型的Al-Mg-Mn合金分别提高了57%、95%和40%;比重力铸造复合材料分别提高了12%、11%和36%。分析发现,复合材料相比无添加Al-Mg-Mn合金强韧性能更高的原因在于TiB_(2)和ZrB_(2)颗粒协同增强细晶强化作用;而挤压铸造成型的复合材料的力学性能优于重力铸造成型的复合材料的主要原因在于挤压力所致的晶粒细化和Orowan强化作用。

条块关系中的双锦标赛体制:激励视角下我国地方体育治理体系的演进与变革

地方体育部门以积极主动的行为促进竞技体育取得辉煌成就,是我国体育制度和体育治理特征的显著优势之一。为理解地方体育部门的行动策略,基于我国行政科层下“条”(冠军锦标赛)和“块”(晋升锦标赛)的制度安排,分析我国地方体育治理体系的激励机制——双锦标赛体制①。研究认为,双锦标赛体制的出现、演化及其时代内涵,与我国的体育事业目标、行政管理体制及其历史阶段性特征紧密相关,地方体育部门的行动逻辑以竞赛成绩为激励目标,并由此形成相应的激励收益与成本。基于此,在构建社会主义市场经济的新型举国体制过程中,新型双锦标赛体制的激励逻辑应当从结果激励向过程激励的价值取向过渡,以适应新时代体育强国的建设目标:以节点式激励的供给思维,促进竞技体育与其他体育领域的“条”上融合;以层化式激励的目标协调,推动体育事业与地方发展战略的“块”上融合;以涌现式发展的激励机制,通过以赛显人才与以赛促发展,实现新型举国体制与市场机制相结合的治理路径。