Zooplankton Feeding Ecology: Contents of Fecal Pellets of the Cyclopoid Copepods Oncaea venusta, Corycaeus amazonicus, Oithona plumifera, and O. simplex from the Northern Gulf of Mexico

Abstract. In situ feeding habits of the cyclopoid copepods Oncaea venusta, Corycaeus amazonicus, Oithona plumifera , and O. simplex were investigated by scanning electron microscope examination of fecal pellets, the contents of which reflected copepod gut contents upon capture. Peilet contents were compared with assemblages of phytoplankton present in surface waters at times of copepod collection. All samples were from the northern Gulf of Mexico. All four copepods fed upon phytoplankton and O. venusta also ingested other crustaceans. Dominant components of fecal pellets generally did not mirror those of available phytoplankton assemblages. In some cases, O. venusta ingested primarily larger-sized particles even when these were not most abundant, and in other cases it did not ingest large cells even when they were present in bloom concentrations. The presence of small (< 2–5 urn diameter) centric diatoms in O. venusta pellets suggests the possibility of feeding by mechanisms other than suspension or raptorial feeding. Limited observations suggest that C. amazonicus and O. plumifera may feed raptorially on larger particles even when these are not particularly abundant, and that the small O. simplex (< 500 nm total length) feeds mainly upon nanoplankton. It appears that cyclopoid feeding mechanisms are complex, and likely more so than those of many calanoids.     

改进的模拟退火－单纯形综合反演方法

实际中的大量地球物理反演是一个多参数、非线性优化问题,所采用的目标函数,即度量由参数化的理论模型得出的预测值与观测值的吻合程度,往往具有多个局部极值．针对这类问题,本文综合全局反演方法具有的全域搜索能力强、局部方法收敛速度快和“均匀设计”布点效率高的特点,提出了模拟退火－单纯性综合反演方法,并通过一维声波非线性反演验证了这种综合方法的搜索能力和效率．     

Parameter identification of inelastic structures under dynamic loads

The generalized model of differential hysteresis contains 13 control parameters with which it can curve‐fit practically any hysteretic trace. Three identification algorithms are developed to estimate the control parameters of hysteresis for different classes of inelastic structures. These algorithms are based upon the simplex, extended Kalman filter, and generalized reduced gradient methods. Novel techniques such as global search and internal constraints are incorporated to facilitate convergence and stability. Effectiveness of the devised algorithms is demonstrated through simulations of two inelastic systems with both pinching and degradation characteristics in their hysteretic traces. Owing to very modest computing requirements, these identification algorithms may become acceptable as a design tool for mapping the hysteretic traces of inelastic structures. Copyright © 2002 John Wiley & Sons, Ltd.     

遗传算法与单纯形法组合的影像纹理分类方法

提出遗传算法(简称GA)与单纯形法组合的影像纹理分类方法(简称GASPX)。单纯形法是一种局部搜索方法，它通过反射，扩张，收缩操作，求得新的单纯形点，组成新单纯形，新单纯形比前一个单纯形更接近局部最优解。这种寻优方法收敛速度快，它与GA组合起来可以改善单独使用GA收敛速度慢的缺陷。由于在组合算法中是多个单纯形的局部区域的并行搜索，避免GA优化过程中过早收敛于局部最优解的现象出现。通过5种不同类别航空影像纹理识别的试验，并与GA的结果作对比，结果表明GASPX法优于GA法。     

改进的单纯形法及其在非线性参数估计中的应用

采用了改进的单纯形法,该算法利用遗传算法的变异操作来增强单纯形法的全局搜索能力,既兼顾了全局收敛性,又具有高效的局部搜索能力。并通过实例验证了该算法的优越性,以及应用于测量上的非线性最小二乘估计的可行性。     

An application of Karmarkar's interior-point linear programming algorithm for multi-reservoir operations optimization

Optimization of multi-reservoir systems operations is typically a very large scale optimization problem. The following are the three types of optimization problems solved using linear programming (LP): (i) deterministic optimization for multiple periods involving fine stage intervals, for example, from an hour to a week (ii) implicit stochastic optimization using multiple years of inflow data, and (iii) explicit stochastic optimization using probability distributions of inflow data. Until recently, the revised simplex method has been the most efficient solution method available for solving large scale LP problems. In this paper, we show that an implementation of the Karmarkar's interior-point LP algorithm with a newly developed stopping criterion solves optimization problems of large multi-reservoir operations more efficiently than the simplex method. For example, using a Micro VAX II minicomputer, a 40 year, monthly stage, two-reservoir system optimization problem is solved 7.8 times faster than the advanced simplex code in MINOS 5.0. The advantage of this method is expected to be greater as the size of the problem grows from two reservoirs to multiples of reservoirs. This paper presents the details of the implementation and testing and in addition, some other features of the Karmarkar's algorithm which makes it a valuable optimization tool are illuminated.     

Location of Tibetan earthquakes──a nonlinear approach by a simplex optimized technique

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三维空间实体间拓扑关系的矩阵描述

三维空间实体及其间拓扑关系的语义描述和形式化表达是三维ＧＩＳ空间数据建模的重要理论基础。在ｋ－维流形的三维空间实体形式化描述方法的基础上,根据三维空间实体的可剖分性,采用顾及维数的九元组描述框架,研究用于构成三维实体的ｋ－单纯形（０≤ｋ≤３）之间的拓扑空间关系,继而研究三维实体间的拓扑空间关系。