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1.
Recursive procedures used for sequential calculations of polynomial basis coefficients in discrete orthogonal moments produce unreliable results for high moment orders as a result of error accumulation. This paper demonstrates accurate reconstruction of arbitrary-size images using full-order (orders as large as the image size) Tchebichef and Krawtchouk moments by calculating polynomial coefficients directly from their definition formulas in hypergeometric functions and by creating lookup tables of these coefficients off-line. An arbitrary precision calculator is used to achieve greater numerical range and precision than is possible with software using standard 64-bit IEEE floating-point arithmetic. This reconstruction scheme is content and noise independent.  相似文献   

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为提高食谱设计质量与效率,提出一种基于交互式进化计算的食谱智能优化方法.根据用户评价值和食谱菜品优化模型确定食谱样本隐式指标与显式指标;基于NSGA-Ⅱ算法获得食谱样本Pareto优化解.为使Pareto优化解更好兼顾用户偏好与营养均衡,引入指标均衡度指导进化.当指标均衡度较低时,采用遗传算法模块对显式指标单独进化,提...  相似文献   

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Application of the ISA-88 standard in industrial batch-process control often leads to repetition of information in recipes and to a low level of their reuse. This problem stems from the deficiencies of the standard batch-process control object model. A solution to the problem is proposed that is based on a more sophisticated object model of equipment and procedural control, with dynamically defined and potentially overlapping unit classes. The new concept, together with its elements, is described, and its use is illustrated and validated by means of a real batch control project. The validation is carried out as a comparison of the number of master recipes and unit procedures created under the new object model with the number of master recipes and unit procedures needed to perform the same functionality using the standard object model. The comparison demonstrates that the proposed approach has a significant advantage.  相似文献   

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Lin  Hao  Zuo  Yuan  Liu  Guannan  Li  Hong  Wu  Junjie  Wu  Zhiang 《World Wide Web》2020,23(6):3001-3023
World Wide Web - In recent years, short text topic modeling has drawn considerable attentions from interdisciplinary researchers. Various customized topic models have been proposed to tackle the...  相似文献   

6.
We have found the probability of double events ??supernova??gamma-ray burst?? (GRB) separated by a time interval of a few years. Their sources can be supernova explosions in binary systems accompanied by formation of a short-lived pair of compact objects which produce a short GRB while merging. Each of the ??500 short SGBs must have an optical precursor, a supernova at a time interval of < 2 years. We discuss the possible relationship between SN 1997ds and GRB 990425.  相似文献   

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M. R. Sleep  S. Holmstrm 《Software》1982,12(11):1082-1084
We show that informing a lazy evaluator that the APPEND operator is associative reduces the overall worst case performance from O(n2) to O(n).  相似文献   

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Given a fine-scale physical theory characterized by an evolutionary system of equations and a set of quantities, defined from the variables of the fine theory, that serve as a coarse representation of the fine scale phenomena, a method for developing an evolutionary set of equations for the coarse quantities is presented. This set may be considered as governing equations for a coarse model corresponding to the fine one since its solutions can be formally shown to generate exact/approximate solutions to the fine theory in a well-defined sense. The method for generating the coarse representation is illustrated on model problems.  相似文献   

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针对微博短文本有效特征较稀疏且难以提取,从而影响微博文本表示、分类与聚类准确性的问题,提出一种基于统计与语义信息相结合的微博短文本特征词选择算法。该算法基于词性组合匹配规则,根据词项的TF-IDF、词性与词长因子构造综合评估函数,结合词项与文本内容的语义相关度,对微博短文本进行特征词选择,以使挑选出来的特征词能准确表示微博短文本内容主题。将新的特征词选择算法与朴素贝叶斯分类算法相结合,对微博分类语料集进行实验,结果表明,相比其它的传统算法,新算法使得微博短文本分类准确率更高,表明该算法选取出来的特征词能够更准确地表示微博短文本内容主题。  相似文献   

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While the availability of large-scale online recipe collections presents opportunities for health consumers to access a wide variety of recipes, it can be challenging for them to discover relevant recipes. Whereas most recommender systems are designed to offer selections consistent with users’ past behavior, it remains an open problem to offer selections that can help users’ transition from one type of behavior to another, intentionally. In this paper, we introduce health-guided recipe recommendation as a way to incrementally shift users towards healthier recipe options while respecting the preferences reflected in their past choices. Introducing a knowledge graph (KG) into recommender systems as side information has attracted great interest, but its use in recipe recommendation has not been studied. To fill this gap, we consider the task of recipe recommendation over knowledge graphs. In particular, we jointly learn recipe representations via graph neural networks over two graphs extracted from a large-scale Food KG, which capture different semantic relationships, namely, user preferences and recipe healthiness, respectively. To integrate the nutritional aspects into recipe representations and the recommendation task, instead of simple fusion, we utilize a knowledge transfer scheme to enable the transfer of useful semantic information across the preferences and healthiness aspects. Experimental results on two large real-world recipe datasets showcase our model’s ability to recommend tasty as well as healthy recipes to users.  相似文献   

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User comments, as a large group of online short texts, are becoming increasingly prevalent with the development of online communications. These short texts are characterized by their co-occurrences with usually lengthier normal documents. For example, there could be multiple user comments following one news article, or multiple reader reviews following one blog post. The co-occurring structure inherent in such text corpora is important for efficient learning of topics, but is rarely captured by conventional topic models. To capture such structure, we propose a topic model for co-occurring documents, referred to as COTM. In COTM, we assume there are two sets of topics: formal topics and informal topics, where formal topics can appear in both normal documents and short texts whereas informal topics can only appear in short texts. Each normal document has a probability distribution over a set of formal topics; each short text is composed of two topics, one from the set of formal topics, whose selection is governed by the topic probabilities of the corresponding normal document, and the other from a set of informal topics. We also develop an online algorithm for COTM to deal with large scale corpus. Extensive experiments on real-world datasets demonstrate that COTM and its online algorithm outperform state-of-art methods by discovering more prominent, coherent and comprehensive topics.  相似文献   

14.
Cui  Zhesen  Wu  Jinran  Ding  Zhe  Duan  Qibin  Lian  Wei  Yang  Yang  Cao  Taoyun 《Neural computing & applications》2021,33(17):11339-11353
Neural Computing and Applications - Time series modelling is gaining spectacular popularity in the prediction process of decision making, with applications including real-world management and...  相似文献   

15.
This paper describes a method for estimating the long-term effects on structures under cyclic changes of loading. For loads less than a certain critical amplitude (shakedown limit), the stress in the structure will a symptote to a cyclic stationary state consisting of an elastic part in response to the cyclic loading, plus a system of self-equilibrating residuals constant in time. It is shown that corresponding to this cyclic stationary state, the creep energy dissipation per cycle of loading is a maximum. Instead of following the exact time history to reach this state, in this paper it is found by a procedure of successive approximations. It corrects the admissible residual stress distribution at the beginning of a cycle by the creep and plastic strains accumulated over an entire cycle, which are in general not compatible, and requires additional self-equilibrating stresses to give an elastic strain distribution such that the total strain satisfies compatibility. The steady state is reached when no further correction is necessary. Convergence may be accelerated by a suitable choice of initial starting value, and by an artificial choice of the cycle time for the best computational convenience, upon which the steady-state solution can be proved to be independent. The procedure is a powerful device to obtain the cyclic steady-state solution, which will give an upper bound to the creep deformation per cycle and may also be used to find the shakedown limit. The formulation of the procedure in conjunction with the finite element method is given in detail and results of a few examples of the analysis are shown.  相似文献   

16.
Block-move is one of the popular operations for genome rearrangement. A short block-move is an operation on a permutation that moves an element at most two positions away from its original position. Heath and Vergara investigated the problem of finding a minimum-length sorting sequence of short block-moves for a given permutation and devised a 4/3-approximation algorithm. In this paper, we present a new 14/11-approximation algorithm for this problem. Firstly, we devise an exact polynomial time alg...  相似文献   

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We describe a multiscale finite element (FE) solver for elliptic or parabolic problems with highly oscillating coefficients. Based on recent developments of the so-called heterogeneous multiscale method (HMM), the algorithm relies on coupled macro- and microsolvers. The framework of the HMM allows to design a code whose structure follows the classical finite elements implementation at the macro level. To account for the fine scales of the problem, elementwise numerical integration is replaced by micro FE methods on sampling domains. We discuss a short and flexible FE implementation of the multiscale algorithm, which can accommodate simplicial or quadrilateral FE and various coupling conditions for the constrained micro simulations. Extensive numerical examples including three dimensional and time dependent problems are presented illustrating the efficiency and the versatility of the computational strategy.  相似文献   

19.
块移动是基因重组的一种重要形式.短块移动是将排列中的元素最多移动到偏离原来两个位置的块移动.Heath和Vergara最先给出短块移动排序近似度为4/3的多项式时间算法.本文设计了近似性能比为14/11的短块移动排序新算法.首先讨论了具有伞形结构排列图的子排列的排序方法,并将这种子排列称为‘伞’,设计了特殊子排列伞短块移动排序的多项式时间精确算法.然后给出关联伞子排列短块移动排序的贪心算法.讨论了5种特殊子排列的短块移动排序方法,证明了它们短块移动距离的新下界,从而证明此贪心算法的近似性能比为14/11,这是目前解答短块移动排序问题近似性能比最小的多项式近似算法.  相似文献   

20.
We show that for any alphabet there is a setL * such that ifC is any infinite co-infinite context-free language over , thenL splitsC (i.e., each ofL C,L , C, and is infinite).Preparation of this paper was supported in part by the National Science Foundation under Grant No. MCS77-11360.  相似文献   

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