EM算法的研究及其在文本处理中的应用

引入EM这一个经典的迭代算法,对EM算法进行具体的推导,并对算法的具体执行步聚做进一步的描述;接着对如今常用的几种文本分类的方法做了概括,重点分析Bayes分类方法,并将EM与Bayes分类方法进行结合,提高Bayes的分类精度,并在综述里对未来海量数据时代怎样来弥补EM算法的不足做简要的介绍.     

Strategies for simultaneous multiple autonomous underwater vehicle operation and control

Under sampling of the coastal oceans remains a persistent problem for standard oceano-graphic measurement practice wherein an instrument package is tethered to a research vessel. The overhead costs associated with operating a large research vessel impose a strict minimum on the cost of data collected. Owing to the overheads, significant improvements in sampling technology on the tethered platform can only produce modest gains in the cost effectiveness. In contrast, untethered vehicles if operated simultaneously have the potential to increase cost effectiveness significantly by distributing the overhead costs over several sampling platforms. Furthermore, synoptic and pseudosynoptic data can be collected with multiple autonomous underwater vehicles (AUVs), thereby providing the type of information critical to dynamic process modeling unattainable with non-synoptic data. While the goal of simultaneous multiple-vehicle operation has been espoused over the last few years, AUV technology and practice have until recently been too immature to realize that potential. Recently, Florida Atlantic University (FAU) has developed a new series of modular AUVs with the express purpose of supporting multiple sensors and multiple-vehicle operation. This series of vehicle is called the Ocean Explorer of which three have been produced so far. This paper will explore some of the associated navigation, tracking, control and deployment problems associated with multiple-vehicle operation in coastal applications. In addition, the characteristics of the component level intelligent distributed control system, integrated data logger and vehicle control system will be discussed. In particular this paper will discuss how FAU has applied the concepts of elastic constraint propagation and the symmetric fuzzy decision-making model to AUV control systems. Some results of early experiments in synoptic data collection with a conductivity, temperature and depth (CTD) sensor using multiple AUVs for the determination of horizontal structure will be described.     

关于征收集体土地补偿费标准问题的探讨

目前水利水电工程建设征收集体土地补偿标准存在差异,各地采用的方法不一致。在探讨了各种计算方法利弊的基础上,根据征地补偿费用计算中存在的问题及原因,提出了改进方法,以利于移民工作的开展和社会稳定。     

清苑县南水北调配套工程运行风险评价

南水北调配套工程运行风险评估体系属于复杂的系统问题,其模糊性在评估中应予以考虑。基于模糊识别理论,采用非线性模型对清苑县南水北调配套工程运行风险进行评价。结果表明,清苑县南水北调配套工程运行风险等级介于2级与3级之间,略偏于2级,属于低风险等级。评价过程与评价结果不仅可为清苑县南水北调配套工程的安全管理提供参考意义,而且表明非线性模型在南水北调配套工程运行风险评价中具有良好的适用性。     

3D 游戏中“影子光环”特效的实现算法

3D游戏中,常常会出现一种紧贴地面的“光环”特效,这些“光环”类似于人物的影子。分析了“光环”特效与游戏地形的关系,提出了一种实用的“光环”特效实现算法。借助该算法,游戏中的“光环”将跟随人物进行移动,并且贴伏着地面,随着地表的凹凸而起伏变化。这种算法已成功应用于多款3D游戏,并很好地与各种程序引擎相结合。     

3D 游戏中“刀光剑影”特效的实现算法

＂拖影＂,就是指3D游戏中,冷兵器在舞动时所＂拖＂出的光影。分析了＂拖影＂特效的图形变化规律,提出了一种实用的＂拖影＂特效实现算法。借助该算法,应用程序可以根据兵器的运动轨迹,自动产生＂拖影＂效果。最后,还结合实际应用的经验,对算法进行了改进。这种算法已成功应用于多款3D游戏,并很好地与各种程序引擎相结合。     

牛蒡脆粒冰淇淋加工工艺研究

探讨了牛蒡粒添加量、复合甜味剂添加量及复合稳定剂添加量对冰淇淋性能的影响,设计了新配方,开发了新产品。     

Exploring a novel approach to fabricate vanadium carbide encapsulated into carbon nanotube (VC@C) with large specific surface area

A novel approach to the fabrication of vanadium carbide encapsulated into carbon nanotube (VC@C) core-shell structured composite by thermal treatment with the precursor V₃O₇·H₂O@C was developed for the first time. The as-obtained VC@C were characterized by X-ray powder diffraction (XRD), Raman spectrum, energy-dispersive X-ray spectrometer (EDX), elemental analysis (EA), Fourier transform infrared spectroscopy (FT)–(IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET). The results showed that VC@C with core-shell structures could be successfully synthesized at 1000 °C for 2 h. The specific surface area, average pore size and measured pore volume of VC@C were 135·46 m²/g, 4·443 nm and 0·180 cm³/g, respectively indicating that the as-obtained VC@C composite could be used as a mesoporous material. Furthermore, thermal behaviour of the as-obtained VC@C composite in air was investigated by thermo-gravimetric/differential thermal analyser (TG/DTA). The experimental result revealed that the carbon coated on the surface of VC has high activity with O₂ in air atmosphere.     

摆线钢球行星传动啮合副非线性力学性能研究

摆线钢球啮合副为空间曲面啮合结构,啮合副承载与变形之间的非线性关系以及啮合副接触区扩展均会对其力学性能产生较大的影响。该文首先利用超静定方法建立了啮合副非线性力学模型,根据啮合力与阻力矩作功相等的原理推导出时变的啮合力函数。然后将啮合力转换为啮合接触区上的椭球状分布载荷,利用叠加法对接触区微元在集中力作用下的变形与应力结果进行积分,给出了接触区变形挠曲面方程、接触表面下各应力函数,以及最大切应力的深度位置。最后根据钢球位置方程,建立了啮合副不同啮合位置的有限元模型,对钢球与摆线槽的啮合过程进行了数值模拟,分析了啮合副应力分布状态以及啮合点等效应力的变化规律。结果表明:采用啮合副非线性力学模型和接触区分布载荷减少了线弹性和集中力简化处理造成的误差,为啮合副承载状态提供了更符合实际的计算结果。     

Low-carbon Economy and Eco-design of Commodity Packing

Research situation of eco-design is analyzed,and then thoughts and methods of eco-design are discused.The eco-design includes packaging modularization,dematerialization,energy-saving and bio-simulation.