建筑结构连续倒塌的数值模拟方法对比研究

建筑结构连续倒塌,是一类由偶然作用引起,可能造成重大生命财产损失的结构安全事故。针对建筑结构连续倒塌的数值模拟问题,本文分析了结构倒塌过程中面临的力学计算难点,对比研究了常用的数值模拟方法,并介绍了作者提出的质点元法。     

基于方位向预处理和后处理的TOPSAR成像方法

Burst工作模式和方位波束主动扫描使得TOPSAR(Terrain Observation by Progressive scans SAR)回波信号同时具备ScanSAR和聚束模式回波信号特点,即方位输出时间混叠和多普勒频谱混叠。虽然时域和频域同时升采样操作能够解决混叠问题,但同时带来成像运算量明显提高和内存消耗显著增大的问题。针对TOPSAR回波信号特殊的方位时频关系,该文提出一种结合方位向预处理和后处理的TOPSAR成像方法。该方法利用复制拼接和去斜的方法来解决混叠问题,利用信号截取操作剔除干扰信号,同时还可以减少采样点数,提高算法运算效率。点目标和分布目标的仿真结果验证了这种成像方法的有效性。     

一种基于循环移位矩阵的LDPC码构造方法

具有准循环结构的低密度奇偶校验码(QC-LDPC Codes)是目前被广泛采用的一类LDPC码。本文提出了一种结合PEG算法构造基于循环移位矩阵的QC-LDPC码的方法。该方法首先将QC-LDPC码传统的基于比特的二分图简化为基于Block的二分图,然后在该图中采用PEG算法遵循的环路最大原则确定每一个循环移位矩阵的位置,最后根据QC-LDPC码的环路特性为每一个循环移位矩阵挑选循环移位偏移量。利用该算法,本文构造了长度从1008bit到8064bit,码率从1/2到7/8各种参数的LDPC码。仿真结果表明,本文构造的LDPC码性能优于目前采用有限几何、两个信息符号的RS码、组合数学等常用的代数方法构造的QC-LDPC码。     

基于轻量化渐进式残差网络的图像快速去模糊

基于深度学习的去模糊方法已经取得了较大进展,但是随着网络层数加深,去模糊网络需要更多的计算资源和内存消耗,难以用于实际场景。针对目前的去模糊网络参数量大、运算时间长等问题,该文设计了一种轻量快速的渐进式残差去模糊网络。该网络使用浅层残差网络作为基准模型,可充分利用图像的局部特征信息,加强反向传播时的信息流通。同时,通过多阶段递归调用残差网络并进行参数共享,可大大简化网络模型,减少网络参数。为了进一步提高去模糊网络的特征重建能力,该文引入特征重标定模块进行特征融合,对输入图像与各个残差网络的输出特征图进行通道加权,并对特征图的空间信息进行自适应选择,实现更好的特征重建。实验结果表明,所提算法网络模型参数量小、运行速度快,大幅度领先于现有算法,且对各种空域可变模糊去除均可实现理想复原效果。     

基于9/7双正交小波的一种高效矢量量化算法

该文提出一种用于图像压缩的矢量量化算法,该算法用9/7双正交小波对图像进行分解,利用三个方向上各自小波系数之间的相关性,构造符合其特征的跨频带矢量,提高了图像的编码效率和重构质量,同时采用了新的矢量量化技术渐进构造聚类(PCC),实验结果证明,该算法在未熵编码的条件下,获得 PSNR32dB的重构图像,比特率高达 0.141 bpp.而且实现方法十分简单。     

基于Pro/E-PDX的焊片连续模设计

介绍了基于Pro/E软件的"连续模设计系统Progressive Die Extension (PDX)"的应用。并结合实例说明了利用PDX设计冲压连续模的过程及方法。     

Progressive Freeze Concentration for Volume Reduction of Produced Water and Biodiesel Wastewater

One way to conserve fresh water resources is by reusing water from wastewater. For instance, water can be removed from wastewater through formation of ice crystal layers by progressive freeze concentration (PFC). The application of PFC to remove water from produced water and biodiesel wastewater was assessed through the final concentration of concentrated wastewater and purity of melted ice crystals. No PFC study has been done on these applications. In order to evaluate the efficiency of PFC, the effective partition constant (K) and separation efficiency (S_E) were calculated for the effect of stirring rate and coolant temperature. The results demonstrate that PFC is a more practical method for produced water, as compared to biodiesel wastewater which is based on the value of low K and high S_E.     

Three-dimensional Entity Resolution with JedAI

Entity Resolution (ER) is the task of detecting different entity profiles that describe the same real-world objects. To facilitate its execution, we have developed JedAI, an open-source system that puts together a series of state-of-the-art ER techniques that have been proposed and examined independently, targeting parts of the ER end-to-end pipeline. This is a unique approach, as no other ER tool brings together so many established techniques. Instead, most ER tools merely convey a few techniques, those primarily developed by their creators. In addition to democratizing ER techniques, JedAI goes beyond the other ER tools by offering a series of unique characteristics: (i) It allows for building and benchmarking millions of ER pipelines. (ii) It is the only ER system that applies seamlessly to any combination of structured and/or semi-structured data. (iii) It constitutes the only ER system that runs seamlessly both on stand-alone computers and clusters of computers — through the parallel implementation of all algorithms in Apache Spark. (iv) It supports two different end-to-end workflows for carrying out batch ER (i.e., budget-agnostic), a schema-agnostic one based on blocks, and a schema-based one relying on similarity joins. (v) It adapts both end-to-end workflows to budget-aware (i.e., progressive) ER. We present in detail all features of JedAI, stressing the core characteristics that enhance its usability, and boost its versatility and effectiveness. We also compare it to the state-of-the-art in the field, qualitatively and quantitatively, demonstrating its state-of-the-art performance over a variety of large-scale datasets from different domains.The central repository of the JedAI’s code base is here: https://github.com/scify/JedAIToolkit .A video demonstrating the JedAI’s Web application is available here: https://www.youtube.com/watch?v=OJY1DUrUAe8.     

东濮凹陷户部寨构造石油地质特征及勘探潜力分析

本文通过对东濮凹陷户部寨结构的地层层序，构造格局与特征及沉积特征的分析，论述了沙三、四段油气藏形成条件，提出本区主要发育低渗透断层遮挡油气藏、构造－岩性油气藏和岩性油气藏。在此基础上，指出了户部寨构造的勘探潜力及勘探方向。     

毛细管铝封无搭边级进冲挤技术

将挤孔——切连皮——落料——空心件正挤压4种工序巧妙地复合在一套模具上，而且模具结构并不复杂，成功地在400kN冲床上实施了该工艺，使空心毛细管铝封片级进挤压工艺生产率达到每分钟60件，大幅度提高了生产效率。本还在落料工序中采用无搭边新技术，一改冲裁落料中有搭边的常规模式，减少了搭边损耗，大大提高了铝板材的利用率。