Microstructure evolution during reheating of a Nb-bearing steel I. Metallographic examination

Cooled in water after the isothermal relaxation of deformed austenite for different timea, a Nb-bearing microalloyed steel always exhibits synthetic microstructures of bainitic ferrite, granular bainite and acicular ferrite. When these samples were reheated to and held at 650 or 700℃, the non-equilibrious microstructures tend to evolve into equilibrious ones. The sample relaxed for 60 s displays the highest thermostability, while the microstructure evolution is the quickest in the sample relaxed for 1000 s even though it is the softest before reheating. Softening is not a single process occurring during reheating, in which the hardness fluctuates with time. There are two peaks in the hardness-time curve of each sample having undergone relaxation, while a single peak occurs in the curve of the sample having not been relaxed. Pre-strain accelerates the evolution process. These results indicate that the thermostability of microstructures is determined by their history of formation to a considerable degree.     

贫化铀的环境污染影响及其对人体健康的危害

贫化铀是铀富集过程中产生的副产品。由于其独特的物理特性,被广泛开发利用到民用和军事用途。“海湾战争综合症”和“巴尔干综合症”引起了人们对贫铀使用后,对环境污染的影响和对人体健康效应研究的重视。贫铀的危害来自化学毒性和放射性毒性两个方面。由于贫铀的放射性比活度低,而且主要发射α粒子,所以来自贫铀的辐射伤害主要是吸入贫铀气溶胶后对肺和其他器官较长时间的内照射。     

基于NiosⅡ和SD卡的数据采集系统的设计

在NiosⅡ软核处理器上采用SD卡设计了一种嵌入式文件系统,并在该文件系统和FPGA的基础上设计了一种便携式数据采集系统.     

水泥浆体的热分析动力学

以差示扫描量热法为手段,进行了水化硅酸盐水泥浆体热分析动力学的研究.采用Kim-Park,Flynn-Wall-Ozawa和Friedman法计算了升温过程水泥浆体各阶段吸热反应活化能和反应级数.结果表明:升温过程中水泥浆体呈现3个吸热反应阶段,随温度升高各反应阶段活化能逐渐升高;Kim-Park,Flynn-Wall-Ozawa和Friedman三种方法较好地分析了前2个反应阶段的反应活化能和反应级数,第一阶段的反应活化能小于第二阶段,但反应级数n却大于后者;对于前2个吸热反应阶段,Kim-Park和Flynn-Wall-Ozawa均能较好地进行动力学分析,但Friedman法对于第三阶段即C-S-H发生脱水过程的反应活化能计算误差较大.     

ICP-AES法测定低、微碳铬铁中硅、锰和磷含量

介绍了邯钢技术中心开发的用ICP-AES法同时测定低、微碳铬铁中硅、锰和磷的方法。试样先用盐酸溶解,在加入一定量的过氧化氢加热,然后定容。结果表明,该方法的准确度和精密度都能满足国标要求,效果良好。该法与传统化学湿法相比,分析时间可由原来的8h缩短到3h,提高了工作效率。     

直吹管内煤粉燃烧的数值模拟

高炉喷煤粉时,由于煤粉的不完全燃烧,在风口处会产生未燃煤粉,影响高炉的透气性.利用商业软件fluent研究了煤粉在直吹管内的燃烧情况,通过对不同的喷吹量和粒径对煤粉燃烧进行分析,得到煤粉在直吹管内燃烧大致情况.当颗粒的直径从30 μm增加到90 μm时,煤的燃尽率从 37.3 %降低到28.8 %,模拟结果与实际基本符...     

莱钢机械厂铸钢车间1^#电弧炉短网系统改造

文章介绍了莱钢机械厂铸钢车间１＃电弧炉短网系统的改造过程。通过改造,提高了导电横臂的机械强度,降低了系统的阻抗,吨钢电耗降低了１７．２ｋＷ·ｈ,年直接经济效益达７９．７１万元。     

工程项目招标投标工作在实际运用中应注意的几个问题

论述了工程项目招标投标工作在实际运用中应注意唯价格论、层层转包、招投标双方不平等等问题,指出要加强管理,健全法制,使招投标工作健康发展。     

Immune clonal coevolutionary algorithm for dynamic multiobjective optimization

In this paper, a new evolutionary algorithm, called immune clonal coevolutionary algorithm (ICCoA) for dynamic multiobjective optimization (DMO) is proposed. On the basis of the basic principles of artificial immune system, the proposed algorithm adopts the immune clonal selection to solve DMO problems. In addition, the theory of coevolution is incorporated in ICCoA in global operation to preserve the diversity of Pareto-fronts. Moreover, coevolutionary competitive and cooperative operation is designed to enhance the uniformity and the diversity of the solutions. In comparison with NSGA-II, immune clonal algorithm for DMO and direction-based method, the simulation results obtained on 5 difficult test problems and on related performance metrics suggest that ICCoA can achieve better distributed solutions and be very effective in maintaining the uniformity of Pareto-fronts.     

基于彩色图像边缘差分的运动目标检测算法

针对目前常用的运动目标提取易受到噪声影响、易出现阴影和误检漏检等情况,提出了一种基于Sobel算子的彩色边缘图像检测和帧差分相结合的检测方法。首先用Sobel算子提取视频流中连续4帧图像的彩色边缘图像,然后将边缘图像进行隔帧差分相与,提取出较精确的运动目标边缘轮廓。提取的轮廓经过一系列的形态学操作填充,可得到完整的运动目标。实验结果表明,该方法对运动目标边缘轮廓提取准确,抗噪能力强,且鲁棒性好。