一种改进的数据求精证明规则

提出一种改进的数据求精规则,并用关系模式进行描述。引入全局状态来描述程序所有可能的输入和输出,允许非平凡的初始化,允许前向模拟和后向模拟,能应用于消除具体模型的不确定性晚于消除抽象模型的不确定性的情况。并用实例说明了在Isabelle定理证明器中规则的应用方法。     

一种改进的降尺寸视频转码算法

在Diversity &; Importance架构的基础上提出一种改进的空间降尺度视频转码算法,利用方差作为转码目标宏块的运动矢量测度因子,并通过自适应阈值的分类方法对不同视频序列选择合适的重编码模式。该算法比传统的运动矢量合成方法提高了约1dB的PSNR,在保持较高转码图像质量的同时有效地控制了编码长度,其转码后码流长度只相当于AMVR-DIM方法产生码流的40%~95%。     

Compositional CSP Traces Refinement Checking

Compositional verification using assume-guarantee reasoning has recently seen an uprise due to the introduction of automatic techniques for learning assumptions. In this paper, we transfer this technique to a setting with CSP as modelling and property specification language, and present an approach to compositional traces refinement checking. The approach has been implemented using the CSP model checker FDR as teacher during learning. The implementation shows that the compositional approach can both drastically outperform as well as underperform FDR's performance, depending on the example at hand.     

基于上下文相关的构件求精方法

为了有效地复用构件,首先提出了上下文有关的求精文法,并为此对上下文和上下文相关概念进行了重定义;接着将该文法引入到体系结构求精中,并从结构、行为、属性方面对构件求精进行了分析,然后为基于上下文有关的构件求精方法建立了模型,阐述了构件求精的过程;最后通过实例进一步说明了该求精方法。     

软件体系结构求精研究

为了保证软件质量,提高软件可靠性、可重用性和可维护性,软件体系结构这一概念自提出以来就得到广泛关注,成为软件工程的一项重要研究领域。软件体系结构求精作为体系结构从抽象到具体的形式化方法,连接了体系结构分析到具体实现之间的鸿沟,从而有效地保证了软件体系结构的层次性和可跟踪性。良好的软件体系结构求精方法使得软件开发自动化．加速软件产品的交付过程,降低软件成本,以及提高软件质量。针对体系结构求精研究的主要内容,较系统地阐述了几种体系结构求精分类方法,并对求精检测的相关内容作了介绍,最后是对体系结构求精以后工作的展望。     

Cu-8%Ag合金的超重力凝固:微观组织

在常重力场和N g超重力场下制备了Cu-8%Ag(质量分数)合金试样,研究了超重力对Cu-8%Ag合金凝固组织的影响。结果表明,超重力引起的熔体对流对试样底部的冲刷作用强于试样顶部,造成底部柱状枝晶的生长弱于试样顶部,超重力试样得到了细小均匀的等轴晶区,Ag棒状析出相的直径由常重力的56.1 nm细化到超重力下的39.2 nm,超重力没有产生明显的宏观偏析,但会影响Ag在Cu基体和离异共晶组织中的分布。     

基于改进轻量级秩扩展网络的人脸表情识别方法

人脸表情识别作为人机交互的一种重要方法,广泛应用于智能医疗、公安测谎系统、车载安全系统等领域。现有人脸表情识别方法多数存在参数量冗余、计算成本高、特征表达瓶颈等问题。提出一种基于改进轻量级秩扩展网络ReXNet的人脸表情识别方法。通过构建改进的ReXNet以提取人脸表情特征,在参数量较少的条件下解决特征表达瓶颈的问题,增强对表情局部特征的关注,获得高层次的表情特征,同时融合坐标注意力模块,将位置信息嵌入到通道注意力中,精准地定位和识别感兴趣的特征,建立位置信息与局部特征之间的长依赖关系,减少计算开销。在此基础上,将细化模块引入到改进的网络架构中,利用类别上下文信息细化分类结果,增强类间的分化效果,从而提高人脸表情识别的准确率。实验结果表明,该方法在RAF-DB和FERPlus数据集上的人脸表情识别准确率分别达到88.43%和88.8%,相比VGG16-PLD、SHCNN、ResNet+VGG等方法,具有较高的准确率和较优的鲁棒性。     

Combined effects of high-temperature rolling and ultrafast cooling on the mechanical properties of low-carbon steel

The role of ultrafast cooling (UFC) on the grain refinement of ferrite, the precipitation behavior of cementite particles and the mechanical properties of a mild steel (Q235 grade) was evaluated by applying laminar cooling and UFC and varying the finish cooling temperature ranges during UFC after hot rolling. While UFC refined the ferrite grains, it accumulated the degeneration of pearlite, resulting in complete disappearance of the laminar pearlite at relatively low finish cooling temperatures. The minimum mean size of spheroidized cementite particles reached ~110?nm. Meanwhile, the enhancement of UFC on tensile strengths of mild steels mainly resulted from the grain refinement of ferrite and the precipitation strengthening of cementite particles; however, the contribution varied with the finish cooling temperature of UFC. A modified Ashby–Orowan model was also used for evaluating the yield strength increment of medium plates. This work will provide a theoretical basis for the diversity control of microstructure and for developing stronger and tougher mild steels by introducing UFC technology after high-temperature rolling.     

Dual‐horizon peridynamics

In this paper, we develop a dual‐horizon peridynamics (DH‐PD) formulation that naturally includes varying horizon sizes and completely solves the ‘ghost force’ issue. Therefore, the concept of dual horizon is introduced to consider the unbalanced interactions between the particles with different horizon sizes. The present formulation fulfills both the balances of linear momentum and angular momentum exactly. Neither the ‘partial stress tensor’ nor the ‘slice’ technique is needed to ameliorate the ghost force issue. We will show that the traditional peridynamics can be derived as a special case of the present DH‐PD. All three peridynamic formulations, namely, bond‐based, ordinary state‐based, and non‐ordinary state‐based peridynamics, can be implemented within the DH‐PD framework. Our DH‐PD formulation allows for h‐adaptivity and can be implemented in any existing peridynamics code with minimal changes. A simple adaptive refinement procedure is proposed, reducing the computational cost. Both two‐dimensional and three‐dimensional examples including the Kalthoff–Winkler experiment and plate with branching cracks are tested to demonstrate the capability of the method. Copyright © 2016 John Wiley & Sons, Ltd.