Fast agglomerative hierarchical clustering algorithm using Locality-Sensitive Hashing

The single linkage method is a fundamental agglomerative hierarchical clustering algorithm. This algorithm regards each point as a single cluster initially. In the agglomeration step, it connects a pair of clusters such that the distance between the nearest members is the shortest. This step is repeated until only one cluster remains. The single linkage method can efficiently detect clusters in arbitrary shapes. However, a drawback of this method is a large time complexity of O(n ²), where n represents the number of data points. This time complexity makes this method infeasible for large data. This paper proposes a fast approximation algorithm for the single linkage method. Our algorithm reduces the time complexity to O(nB) by rapidly finding the near clusters to be connected by Locality-Sensitive Hashing, a fast algorithm for the approximate nearest neighbor search. Here, B represents the maximum number of points going into a single hash entry and it practically diminishes to a small constant as compared to n for sufficiently large hash tables. Experimentally, we show that (1) the proposed algorithm obtains clustering results similar to those obtained by the single linkage method and (2) it runs faster for large data than the single linkage method. Hisashi Koga received the M.S. and Ph.D. degree in information science in 1995 and 2002, respectively, from the University of Tokyo. From 1995 to 2003, he worked as a researcher at Fujitsu Laboratories Ltd. Since 2003, he has been a faculty member at the University of Electro-Communications, Tokyo (Japan). Currently, he is an associate professor at the Graduate School of Information Systems, University of Electro-Communications. His research interest includes various kinds of algorithms such as clustering algorithms, on-line algorithms, and algorithms in network communications. Tetsuo Ishibashi received the M.E. degree in information systems design from the Graduate School of Information Systems at the University of Electro-Communications in 2004. Presently, he is a system engineer at Fujitsu Broad Solution & Consulting Inc. Toshinori Watanabe received the B.E. degree in aeronautical engineering in 1971 and the D.E. degree in 1985, both from the University of Tokyo. In 1971, he worked at Hitachi as a researcher in the field of information systems design. His experience includes demand forecasting, inventory and production management, VLSI design automation, knowledge-based nonlinear optimizer, and a case-based evolutionary learning system nicknamed TAMPOPO. He also engaged in FGCS (Fifth Generation Computer System) project of Japan and developed a new hierarchical message-passing parallel cooperative VLSI layout problem solver that ran on PIM (Parallel Inference Machine) in 1991. Since 1992, he has been a professor at the Graduate School of Information Systems, University of Electro-Communications, Tokyo, Japan. His areas of interest include media analysis, learning intelligence, and the semantics of information systems. He is a member of the IEEE.     

利用三维模型和立体像对估算飞行目标位姿

提出了一种新的飞行目标位置姿态参数解算方法.该方法基于目标的三维模型和立体像对:从目标模型外表面选取若干模型控制点并结合相机参数进行可见性判断,将两相机均可见的点投影到左右图像上,进而依据同名像点在立体像对中的灰度差平方和达到最小的准则将目标位置和姿态参数的求解问题转化为最优化问题.文中采用L-M算法解决这个优化问题以获取目标位置姿态参数最优解.仿真实验结果表明文中提出的算法是正确、有效的.     

基于光照无关图的阴影去除方法

为了在检测目标时排除阴影的干扰,首先论述了光照无关图的原理及其重要性质,然后在此基础上提出了一种基于光照无关图的阴影去除方法。该方法根据光学成像原理通过对图像进行变换来得到一幅与光照无关的灰度图,以达到去除阴影的目的。同时针对该方法需事先测定摄像机的光照无关角的不便之处,还提出了基于直方图统计的摄像机光照无关角判定法则。通过对大量不同场景下视频监控图像的实际测试结果表明,基于光照无关图的阴影去除方法以及基于直方图统计的光照无关角判定方法,可以有效去除目标阴影,并可准确分割目标。     

钢包炉精炼不同吹氩工艺对夹杂物去除效果的研究

在水模试验的基础上改变了天津钢管集团有限公司第一炼钢厂150 t钢包的吹氩工艺,通过示踪剂追踪、金相分析、大样电解、扫描电镜(SEM)、电子探针(EDS)等手段比较分析了改进后的工艺与原工艺对石油套管用钢39Mn2V非金属夹杂物的去除效果.结果表明,原工艺精炼前后氧的质量分数降低率为35.42%,微观夹杂物和大颗粒夹杂物的去除率分别为59.85%、93.43%,而改进后的工艺精炼前后对应值为44.31%、64.29%、95.88%.由此可见,改进后的工艺在降低氧含量和去除夹杂物方面均优于原工艺.     

软锰矿、菱锰矿吸收烧结烟气中的SO2制取硫酸锰

现代钢铁联合企业的高炉-转炉流程是铁-煤化工过程,针对该流程中烧结工序排放含二氧化硫烟气的特点,采用软锰矿、菱锰矿脱硫制取硫酸锰.采用菱锰矿调节和控制矿浆的pH值,利用软锰矿中MnO2的氧化性和SO2的还原性,用软锰矿矿浆在填料吸收塔内进行脱硫试验.试验结果表明:二氧化硫的吸收率在95%以上,该工艺还具有湿法除尘的特性,对烟尘的吸收率达90%以上,且副产品硫酸锰的质量能达到工业级,是一种真正实现"综合治理、变废为宝"的脱硫新技术.     

高氮奥氏体不锈钢熔焊时电弧空间及熔池的氦行为

高氮奥氏体不锈钢是利用氮代替镍进行合金化的一种合金结构钢，氮的固溶存在是材料具备优良性能的前提。焊接是高氮奥氏体不锈钢工程应用需要解决的首要问题之一，氮是影响其焊接性的主要因素，为了获得与母材性能匹配的焊接接头，必须理解熔焊过程中的氮行为。对熔焊时电弧区、熔池区的氮行为进行了分析，以实现焊缝固溶氮含量的有效控制。     

铜离子对硫酸锌溶液中钴返溶的影响及机理

本文研究了对湿法炼锌过程中钴的返溶的影响因素,对反应时间,氧化,锌粉粒度,Cu2 等因素进行了系统的研究.当锌粉量一定时,小颗粒锌粉有较高的初始置换速率,但是也更容易返溶.大颗粒锌粉置换速率慢,但是几乎不返溶.添加了铜离子,返溶明显,而没有添加铜离子的溶液,虽然除钴效果稍差,但是不会返溶或者返溶不明显.然而铜离子的存在对钴的返溶究竟起着何种作用还有待于进一步研究.在锌粉置换过程中,钴返溶的正确的反应为:Zn Co2 →Zn2 Co(s),Co(s) 2OH-→Co(OH)2 2e.     

High Nitrogen Austenitic Stainless Steels Manufactured by Nitrogen Gas Alloying and Adding Nitrided Ferroalloys

 A simple and feasible method for the production of high nitrogen austenitic stainless steels involves nitrogen gas alloying and adding nitrided ferroalloys under normal atmospheric conditions. Alloying by nitrogen gas bubbling in Fe Cr Mn Mo series alloys was carried out in MoSi2 resistance furnace and air induction furnace under normal atmospheric conditions. The results showed that nitrogen alloying could be accelerated by increasing nitrogen gas flow rate, prolonging residence time of bubbles, increasing gas/molten steel interfaces, and decreasing the sulphur and oxygen contents in molten steel. Nitrogen content of 069% in 18Cr18Mn was obtained using air induction furnace by bubbling of nitrogen gas from porous plug. In addition, the nickel free, high nitrogen austenitic stainless steels with sound and compact macrostructure had been produced in the laboratory using vacuum induction furnace and electroslag remelting furnace under nitrogen atmosphere by the addition of nitrided alloy with the maximum nitrogen content of 081%. Pores were observed in the ingots obtained by melting and casting in vacuum induction furnace with the addition of nitrided ferroalloys and under nitrogen atmosphere. After electroslag remelting of the cast ingots, they were all sound and were free of pores. The yield of nitrogen increased with the decrease of melting rate in the ESR process. Due to electroslag remelting under nitrogen atmosphere and the consequential addition of aluminum as deoxidizer to the slag, the loss of manganese decreased obviously. There existed mainly irregular Al2O3 inclusions and MnS inclusions in ESR ingots, and the size of most of the inclusions was less than 5 μm. After homogenization of the hot rolled plate at 1 150 ℃×1 h followed by water quenching, the microstructure consisted of homogeneous austenite.     

焦化废水用改性斜发沸石吸附水中氨氮的研究

研究了焦化废水用改性斜发沸石对水中氨氮的吸附行为,考察了pH值、氨氮初始浓度以及竞争阳离子等对钠型沸石吸附氨氮的影响,同时进行了钠型沸石的吸附动力学研究.     

再生除铅剂精炼除铅的工业试验

进行了再生除铅剂精炼除铅的工业试验。试验表明，锑火法精炼中再生除铅剂的除铅效果与普通除铅剂基本相同，可替代普通除铅剂使用。