用改进的逐次逼近解法计算二维井间电磁场

提出了一种计算积分方程的新方法——改进的逐次逼近解法 (MSAM) ,并用该方法计算了轴对称二维井间电磁场。与传统的逐次逼近解法 (SAM)相比 ,该方法收敛性强 ,应用范围广 ,可适用于高电导率对比地层。由于不必进行直接的大型矩阵求逆运算 ,因此与积分方程的直接解法 (IE)相比 ,该方法计算速度更快 ,所需内存更少。采用矩阵求逆方法计算了成层介质中的二维 Green函数 ,并对含 Green函数的积分进行了简化 ,从而加快了计算速度。数值计算结果显示 ,在地层电导率对比度达到 2个数量级时 MSAM仍收敛 ,且计算结果与直接求解积分方程的结果一致 ,因此 MSAM是一种有效的计算轴对称二维井间电磁场的方法     

NUMERICAL SIMULATION OF STRESS-INDUCED SECONDARY FLOWS WITH HYBRID FINITE ANALYTIC METHOD

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｔｕｒｂｕｌｅｎｔｓｔｒｕｃｔｕｒｅｓｉｎｎｏｎ ｃｉｒｃｕｌａｒｄｕｃｔｓａｎｄｏｐｅｎｃｈａｎｎｅｌｓａｒｅｃｈａｒａｃｔｅｒｉｚｅｄｂｙｌｏｎｇｉｔｕｄｉ ｎａｌｖｏｒｔｉｃｅｓ .Ｔｈｅｓｅｖｏｒｔｉｃｅｓａｒｅｔｈ     

气化炉自动建模系统研究

为了减轻建模人员在建模公式推导、逻辑关系推导和编制仿真程序的工作量，设计了气化炉自动建模系统。该系统在反应物为多种气体、多种固体（均考虑为单筛分）的条件下，按照小室模型的框架自动列写相应各个物质的质量、能量平衡方程，并自动生成相应的计算机程序，方便仿真计算。由于该系统避开了工程中常用的纯数值建模的思路，采用了新的数学工具－以符号运算特长的计算机代数系统为计算平台，才使得该系统具有强大的逻辑关系推导能力。该系统在某气化炉的建模过程中得到了验证和示范，事实表明：该系统大大减少了气化炉的建模工作量，特别是减少由于化学反应假定的不同带来的建模复杂性，对于建模与仿真研究新方法的突破有所贡献。     

Localized audio watermarking technique robust against time-scale modification

Synchronization attacks like random cropping and time-scale modification are very challenging problems to audio watermarking techniques. To combat these attacks, a novel content-dependent localized robust audio watermarking scheme is proposed. The basic idea is to first select steady high-energy local regions that represent music edges like note attacks, transitions or drum sounds by using different methods, then embed the watermark in these regions. Such regions are of great importance to the understanding of music and will not be changed much for maintaining high auditory quality. In this way, the embedded watermark has the potential to escape all kinds of distortions. Experimental results show strong robustness against common audio signal processing, time-domain synchronization attacks, and most distortions introduced in Stirmark for Audio.     

Effects of plant community composition and exposure to wave action on invertebrate habitat use of Lake Huron coastal wetlands

Invertebrate communities from different coastal marsh‐plant communities were compared along wave‐exposure gradients using data from 1994, 1998 and 1999. Data were subjected to correspondence analyses to search for patterns in invertebrate communities in relation to plant‐community structure and wave exposure. In 1994, quantitative plant‐ and sediment‐invertebrate samples were taken from nine habitats: four from inland, subsurface‐connected marshes and five from littoral, emergent marshes. In 1998, sweep‐net samples were taken from 13 plant communities: six on the exposed and seven on the protected side of an island. In 1999, 2–3 plant communities/sites were sampled with sweep nets from four sites around the Bay so that intersite differences between inner, less‐exposed and outer, more‐exposed habitats could be examined. In all three studies, correspondence analyses separated inland, protected or inner sites from littoral, exposed or outer sites, suggesting differences in invertebrate‐community structure. For example, Hydracarina and Asellidae occurred in large numbers in inland sites, but were less common or absent from exposed, littoral sites. Littoral marshes also separated along an exposure gradient with Tanytarsini and Orthocladiinae collectors of organic particles occurring in very high numbers in outer, exposed areas where organic particles from the pelagic zone entered the marsh. Certain plant‐community types clustered together (e.g. wet meadow and Scirpus) while others, such as Typha, stands clustered according to exposure to waves suggesting the importance of both plant‐community structure and wave exposure in determining invertebrate‐community structure. We present a conceptual model that suggests that invertebrates in Great Lakes' marshes are distributed along gradients of decreased mixing of pelagic water and increases in sediment organic matter from outer to inner marsh and between littoral and adjacent inland marshes. Some invertebrates do best on one end of these gradients, while the majority are generalists found across habitat types.     

Nash equilibrium bidding strategies in a bilateral electricitymarket

This paper examines bidding strategies in a bilateral market in which generating companies submit bids to loads. A load accepts electricity delivery from the generator with the lowest bid at its bid price as long as this price is not higher than the load's willingness to pay. Necessary and sufficient conditions of Nash equilibrium (NE) bidding strategy are derived based on a generic generating cost matrix and the loads' willingness to pay vector. The study shows that in any NE, efficient allocation is achieved. Furthermore, all Nash equilibria are revenue equivalent for the generators. Based on the necessary and sufficient conditions, this problem is formulated as an optimal assignment problem. Network optimization techniques are applied to calculate NE bid prices for the generators     

快速施工技术在炼油化工装置检修工程设备基础施工中的应用

1　前言我公司历年来多次承担大型炼油化工装置检修工程设备基础的施工任务。检修中土建工程施工同一般工程相比具有施工工序复杂 (增加了原有基础拆除及原有坚向破除 )、施工工紧 (一般装置检修土建、安装工程总工期为 2 5天左右 )等特点 ,针对这些特点我们采用了快速施工技术 ,较好地保证了工程的施工工期和大型设备吊装所需要的砼抗压强度 ,满足了检修工程对土建工程的要求。2　采用的主要施工技术2 .1　加大模板预制深度　按照设备基础外形尺寸 ,并考虑支模方便、起重运输能力等因素 ,在预制场将设备基础模板预制成三种形式 :(1)塔、容…     

基于ARX模型的压电智能结构振动预测控制

采用预测控制法对压电智能结构的振动主动控制进行了实验研究，通过实验方法建立了系统的ARX模型，并在此基础上设计了预测控制器对结构进行振动主动控制。实验结果验证了该方法在压电智能结构振动主动控制中的可行性和有效性。     

热带城市垃圾典型组分的热解特性研究

对热带城市垃圾的几种典型组分进行了热解实验，得到了它们的失重曲线，通过对失重曲线进行分析，得到了这几种典型组分的热解规律，并通过建立热解动力学模型，求出了其中两种组分的活化能E和频率因子A。