基于视觉传感的超声-MIG焊熔滴行为分析

针对镀锌钢在焊接时对焊接参数难以精确控制,导致焊接接头质量较差,从而对镀锌钢超声-MIG焊接过程中的熔滴过渡机制进行深度研究。实验基于视觉传感器在不同的焊接电参数下,对比了超声-MIG与MIG焊接过程,通过图像处理技术提取熔滴的特征参数。结果表明：在焊接小功率参数下,熔滴过渡方式主要是短路过渡,超声此时会阻碍熔滴过渡,熔滴轮廓面积减少,距离熔池高度增加。当焊接功率增大时,在超声辅助作用下熔滴过渡方式主要是大滴过渡和射流过渡,熔滴的几何尺寸均减少,距离熔池高度减少,向熔池过渡频率增加。最后提出一种焊接过程中的熔滴计数算法,实验验证在1 000帧熔滴图像时间内,熔滴过渡周期最高可达37次,保证焊接过程中质量的稳定性,加速了焊接智能化发展。     

Mechanism for OH-initiated degradation of 2,3,7,8-tetrachlorinated dibenzo-p-dioxins in the presence of O2 and NO/H2O

The atmospheric oxidation of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TeCDD) is investigated theoretically by high-accuracy molecular orbital calculation. The study shows that the OH radical can easily be added to the C atom adjacent to the O atom in dioxin ring to form OH radical adduct. The 2,3,7,8-TeCDD-OH adduct can immediately react with O(2) to form the 2,3,7,8-TeCDD-OH-O(2) adduct which can react with NO or H(2)O to complete the decomposition process. The degradation mechanism varies with the addition position of O(2) and the O-abstraction by NO. The OH radical can be reproduced through the H-abstraction of H(2)O and initiate a new round of degradation. The direct dynamic calculation is performed, and the rate constants is calculated over a temperature range of 200-1200 K, using the canonical variational transition state theory with small-curvature tunneling effect. The four-parameter formula of rate constants with the temperature is fitted and the lifetimes of the reaction species in the troposphere are estimated according to the rate constants, which is helpful for the atmospheric model study on the formation and degradation of dioxin.     

Ф720mm×800mm热轧机试验机组的研制

介绍了我所设计的Ф720mm×800mm热轧机试验机组，并着重介绍该机组所采用的推钢翻钢装置、机架辊装置等新技术及其新装备。     

基于功角测量的同步发电机参数辨识频域法

功角测量为同步发电机参数辨识提供了方便。文中介绍了功角可测时在线频率响应（OLFR）辨识方法的原理，重点分析了OLFR方法的可辨识性，指出采用OLFR方法可以惟一辨识 q轴所有参数和d轴的电抗参数。将OLFR方法与时域辨识方法进行了比较，结果表明:对于 q轴稳态电抗，2种方法都具有很高的精度;对于q轴瞬态参数，OLFR方法辨识效果优于时域辨识;而对于 d轴稳态电抗，采用时域辨识方法得到的参数精度高于OLFR方法。     

Two fast and high-associativity cache schemes

In the race to improve cache performance, many researchers have proposed schemes that increase a cache's associativity. The associativity of a cache is the number of places in the cache where a block may reside. In a direct-mapped cache, which has an associativity of 1, there is only one location to search for a match for each reference. In a cache with associativity n-an n-way set-associative cache-there are n locations. Increasing associativity reduces the miss rate by decreasing the number of conflict, or interference, references. The column-associative cache and the predictive sequential associative cache seem to have achieved near-optimal performance for an associativity of two. Increasing associativity beyond two, therefore, is one of the most important ways to further improve cache performance. We propose two schemes for implementing associativity greater than two: the sequential multicolumn cache, which is an extension of the column-associative cache, and the parallel multicolumn cache. For an associativity of four, they achieve the low miss rate of a four-way set-associative cache. Our simulation results show that both schemes can effectively reduce the average access time     

YH-ITM中数据缓冲部件的设计与实现

智能工具机ＹＨ－ＩＴＭ是一个基于ＲＩＳＣ、支持多种人工智能语言和传统Ｃ语言的通用智能计算机系统。数据缓冲部件ＤＢＵ是该系统中的一个重要组成部分。本文论述了ＤＢＵ的功能、结构、工作状态、对多处理机环境及对Ｐｒｏｌｏｇ的支持，以及对各类访问的处理。     

高分辨率资料处理与储层预测

对地震资料进行提高分辨率处理，需要对影响资料分辨率的因素进行分析，找出其中的主要因素，例如地震子波的主频与频带宽度、时间、空间的采样率、资料信噪比、子波的形状以及大地对地震子波的吸收作用。针对性的解决方法主要包括：采用综合有效的噪音衰减方法提高资料信噪比，拓宽资料有效频带宽度，采用小的时间采样处理，使用零相位子波反褶积，进行一致性能量补偿，用分频剩余静校正法作剩余时差校正，精准的速度分析，叠后进行高频补偿处理拓宽资料频带宽度。采用这些方法处理的资料分辨率得到较好的提高，对地质成像及储层预测起到了积极的作用。     

Atomic force microscopy imaging and 3-D reconstructions of serial thin sections of a single cell and its interior structures

The thin sectioning has been widely applied in electron microscopy (EM), and successfully used for an in situ observation of inner ultrastructure of cells. This powerful technique has recently been extended to the research field of atomic force microscopy (AFM). However, there have been no reports describing AFM imaging of serial thin sections and three-dimensional (3-D) reconstruction of cells and their inner structures. In the present study, we used AFM to scan serial thin sections approximately 60 nm thick of a mouse embryonic stem (ES) cell, and to observe the in situ inner ultrastructure including cell membrane, cytoplasm, mitochondria, nucleus membrane, and linear chromatin. The high-magnification AFM imaging of single mitochondria clearly demonstrated the outer membrane, inner boundary membrane and cristal membrane of mitochondria in the cellular compartment. Importantly, AFM imaging on six serial thin sections of a single mouse ES cell showed that mitochondria underwent sequential changes in the number, morphology and distribution. These nanoscale images allowed us to perform 3-D surface reconstruction of interested interior structures in cells. Based on the serial in situ images, 3-D models of morphological characteristics, numbers and distributions of interior structures of the single ES cells were validated and reconstructed. Our results suggest that the combined AFM and serial-thin-section technique is useful for the nanoscale imaging and 3-D reconstruction of single cells and their inner structures. This technique may facilitate studies of proliferating and differentiating stages of stem cells or somatic cells at a nanoscale.     

静/动载作用下埋地管道力学性能的试验分析

针对埋地管道开展了静载和循环荷载试验,综合分析了荷载类型、加载角度、管道外径和管道材质等因素对管道力学与变形性能以及管周土压力分布规律的影响。结果表明:静载作用下,管周土中垂直土压力大小与加载位置关系密切,水平土压力受“土拱效应”影响显著;管道呈现水平向外鼓胀、垂直径向压缩的椭圆状变形,且承压板荷载越大,管道变形越严重,同时管顶“土拱效应”越显著。循环荷载对埋地管道上方土层的沉降影响明显大于静载;改变承压板角度时效果差异明显,当加载范围关于管道轴线对称时埋地管道所受影响显著。对比不同外径和材质的埋地管道,发现当厚径比相同时,管径越大,壁厚越大,弹性模量也越大,管道的抗变形性能也就越好;公称压力相同时,聚丙烯管道抗变形能力强于外径相等的高密度聚乙烯管道。     

白马崖金矿床地质—地球化学特征及其成矿意义

白马崖金矿床处于康滇地轴北,是康定杂岩体内典型的石英脉—蚀变岩型金矿床。矿区出露古老的变质结晶杂岩基底,多呈刚性较强的块状岩石,岩性以斜长角闪岩、黄铁绢英岩、绢英片岩和构造片岩等为主。矿石矿物以石英为主,占90%以上,含少量绢云母、黄铁矿及其他硫化矿物。矿区断裂以近SN向脆—韧性剪切断裂为主,具多期次活动特点。通过矿床地球化学主量元素、稀土元素、硫同位素及流体包裹体的研究,白马崖金矿区围岩与蚀变岩在稀土元素配分曲线上均表现为缓右倾型;白马崖金矿床δ34S变化于-2.1‰-4.4‰之间,均值为1.6‰;含矿石英中流体包裹体以富含CO2为特征。白马崖金矿床断裂构造发育,深部岩浆流体带来成矿物质,并对围岩进行改造,富集成矿,对于进一步的研究和找矿工作具有一定的指导意义。