低能量沥青温拌技术的应用与实践

低能量沥青温拌技术作为沥青混合料泡沫温拌技术的一种,其生产、施工过程中不需要添加任何温拌剂,因没有温拌剂生产过程的能耗与排放,系统能耗更低,并且在节约成本方面具有明显优势,这使得低能量沥青温拌技术迅猛发展,成为当前世界各国最感兴趣的温拌技术之一。笔者通过其与热拌沥青混合料的对比,介绍了低能量沥青温拌技术在欧洲的应用和实践,提出了低能量沥青温拌技术推广应用需要解决的关键性问题。     

Nondestructive testing and characterization of residual stress field using an ultrasonic method

To address the difficulty in testing and calibrating the stress gradient in the depth direction of mechanical components, a new technology of nondestructive testing and characterization of the residual stress gradient field by ultrasonic method is proposed based on acoustoelasticity theory. By carrying out theoretical analysis, the sensitivity coefficients of different types of ultrasonic are obtained by taking the low carbon steel(12%C) as a research object. By fixing the interval distance between sending and receiving transducers, the mathematical expressions of the change of stress and the variation of time are established. To design one sending-one receiving and oblique incidence ultrasonic detection probes, according to Snell law, the critically refracted longitudinal wave (LCR wave) is excited at a certain depth of the fixed distance of the tested components. Then, the relationship between the depth of LCR wave detection and the center frequency of the probe in Q235 steel is obtained through experimental study. To detect the stress gradient in the depth direction, a stress gradient LCR wave detection model is established, through which the stress gradient formula is derived by the relationship between center frequency and detecting depth. A C-shaped stress specimen of Q235 steel is designedto conduct stress loading tests, and the stress is measured with the five group probes at different center frequencies. The accuracy of ultrasonic testing is verified by X-ray stress analyzer. The stress value of each specific depth is calculated using the stress gradient formula. Accordingly, the ultrasonic characterization of residual stress field is realized. Characterization results show that the stress gradient distribution is consistent with the simulation in ANSYS. The new technology can be widely applied in the detection of the residual stress gradient field caused by mechanical processing, such as welding and shot peening.     

Joining different metallic sheets without protrusion by flat hole clinching process

In this paper, we propose an architecture based on an artificial neural network (ANN), to learn welding skills automatically in industrial robots. With the aid of an optic camera and a laser-based sensor, the bead geometry (width and height) is measured. We propose a real-time computer vision algorithm to extract training patterns in order to acquire knowledge to later predict specific geometries. The proposal is implemented and tested in an industrial KUKA KR16 robot and a GMAW type machine within a manufacturing cell. Several data analysis are described as well as off-line and on-line training, learning strategies, and testing experimentation. It is demonstrated during our experiments that, after learning the skill, the robot is able to produce the requested bead geometry even without any knowledge about the welding parameters such as arc voltage and current. We implemented an on-line learning test, where the whole experiments and learning process take only about 4 min. Using this knowledge later, we obtained up to 95 % accuracy in prediction.     

动态场景下移动机器人视觉SLAM

为实现动态场景下移动机器人自主定位和建图,解决传统视觉里程计方法跟踪效果差及累积误差问题,提升闭环检测的准确性和鲁棒性,提出融合深度学习的同时定位与地图构建方法。采用四叉树算法均匀化特征分布,解决动态场景特征聚集问题;通过优化的目标检测网络识别场景动态语义信息,剔除动态物体对位姿估计的干扰;充分提取场景空间结构信息,结合点特征和线特征实现位姿跟踪及回环检测,构建全局一致的环境地图。TUM数据集和真实场景实验结果表明：改进方法提升了移动机器人定位和建图的准确性和鲁棒性。     

纳米SiO2对以HFC-365mfc为发泡剂的硬质聚氨酯泡沫的性能影响研究

针对以HFC-365mfc为发泡剂制备的环保型硬质聚氨酯泡沫,从压缩强度、泡孔尺寸、扫描电子显微镜照片等多个角度探讨3种不同类型(亲水型:A200,疏水型:R974、R972)的纳米二氧化硅(SiO2)粒子对泡沫性能的影响。结果表明,随着疏水型纳米SiO2加入量的增加,泡沫的压缩强度呈现先降低再升高而后又降低的现象,当加入量为3%(质量分数,下同)时,压缩强度达到最大值,其中,R974效果优于R972;加入A200出现压缩强度降低的现象;泡孔尺寸均呈现先减小后增大的趋势。     

电动车中超级电容控制器的设计

从硬件的拓扑图着手分析超级电容控制器的具体控制方案,以及升压变换器和降压变换器的工作原理,根据控制结构利用相关的硬件资源,选择使用了DSP(TMS320LF2407)器件,并编制了相关的软件程序.     

外源GABA联合超声处理发芽绿豆淀粉的结构特性及血糖指标变化

研究外源γ-氨基丁酸（γ-Aminobutyric Acid,GABA）联合超声处理绿豆淀粉结构特性及血糖指标变化影响,获得低GI值绿豆淀粉制品,该文以不同萌发时间的绿豆淀粉为研究对象,通过扫描电镜、X-射线衍射、傅里叶红外光谱等分析方法,探讨外源GABA协同超声处理对绿豆淀粉萌发过程中结构特性和血糖指标影响。结果表明,处理后,绿豆中总淀粉含量从52.13%下降到发芽96 h的21.18%;发芽12 h时,抗性淀粉含量达到70.65%。发芽后绿豆淀粉颗粒形貌无显著变化。发芽后绿豆淀粉的相对结晶度由39.64%下降到96 h的12.72%,但发芽处理并未改变绿豆淀粉的结晶类型。发芽处理后绿豆淀粉没有产生新的基团,但淀粉晶体结构的有序性降低。发芽后绿豆淀粉的凝沉性增强,其抗消化能力也增强,在发芽12 h时,发芽绿豆淀粉的估计血糖生成指数达到了22.52,相较于未处理时的27.13,可起到减缓血糖升高的作用。外源GABA联合超声处理降低了总淀粉含量,提高了抗性淀粉含量,使绿豆淀粉的消化特性发生了显著变化,为其在功能食品中的应用提供了理论依据。     

Synthetic curli enables efficient microbial electrocatalysis with stainless-steel electrode

Microbial electrocatalysis systems (MES) provide a cutting-edge solution to global problems associated with the environment and energy, but practical applications are hindered by the expensive electrode materials. Although stainless steel (SS) has been proposed as a promising inexpensive candidate, poor cell/SS interaction results in a low performance for MES. Here, a new synthetic biology approach was established for reinforcing the cell/SS interaction. Hybridized curli nanofibers fused with a metal-binding domain were heterogeneously expressed onto the cell surface, which realized efficient cell binding with the SS electrode. Consequently, it enabled a ~420-fold improvement of the anodic power output and a substantial enhancement of the cathodic Coulombic efficiency (from 0.6 to 4% to over 80%) with an SS electrode. This work demonstrates low-cost MES with an SS electrode and introduces a new avenue to engineer the cell/electrode interaction, which is promising for future practical applications of MES.     

2,2-二羟甲基十二酸的合成

研究了以月桂醛(正十二醛)、甲醛、过氧化氢为原料,经羟醛缩合、过氧化氢氧化合成2,2-二羟甲基十二酸的方法,探讨了原料摩尔比、催化剂或氧化剂用量、反应温度和时间对羟醛缩合反应和氧化反应的影响。结果表明,月桂醛(正十二醛)与甲醛摩尔比为2.6∶1.0、催化剂与月桂醛摩尔比为0.51∶1.0、羟醛缩合反应温度为50℃、反应时间为3 h,合成的2,2二-羟甲基十二醛收率为46%;H2O2与2,2二-羟甲基十二醛摩尔比为1.1∶1.0,氧化反应温度为70℃、反应时间为7 h,合成的2,2二-羟甲基十二酸收率为86%。并用13C和1H核磁共振谱表征了2,2-二羟甲基十二酸的结构。     

划分归并算法在MPLS VPN流量工程中的应用

介绍了基于MPLS虚拟专用网实施流量工程的优势所在。针对VPN用户业务流到多条标记交换路径的映射过程中产生的“带宽碎片”问题,提出了一种基于划分归并算法的流量分配方案。详细描述了该算法,并对该算法进行了仿真,把算法在不同条件下的计算结果同贪婪算法进行了比较。