نتایج جستجو برای: semi empirical methods

تعداد نتایج: 2149770  

Journal: :Wiley interdisciplinary reviews. Computational statistics 2013
Eric Bair

Cluster analysis methods seek to partition a data set into homogeneous subgroups. It is useful in a wide variety of applications, including document processing and modern genetics. Conventional clustering methods are unsupervised, meaning that there is no outcome variable nor is anything known about the relationship between the observations in the data set. In many situations, however, informat...

Journal: :فیزیک زمین و فضا 0
علی اکبر سبزی پرور دانشیار، گروه مهندسی آب، دانشکده کشاورزی، دانشگاه بوعلی سینا، همدان، ایران مجتبی شادمانی کارشناس ارشد مهندسی آبیاری، گروه مهندسی آب، دانشکده کشاورزی، دانشگاه بوعلی سینا، همدان، ایران

introduction: evaporation and evapotranspiration are two major components of hydrological cycle which are very important for agricultural studies as well as water resources management. so far, various methods have been addressed for the estimation of daily reference crop evapotranspiration (et0). among them, fao penman-montieth 56 (pmf-56) (allen et al., 1998) is widely used as a standard metho...

2016
Liran Liu Shi Feng Daling Wang Yifei Zhang

Nowadays, more and more people are willing to express their opinions and attitudes in the microblog platform. Stance detection refers to the task that judging whether the author of the text is in favor of or against the given target. Most of the existing literature are for the debates or online conversations, which have adequate context for inferring the authors’ stances. However, for detecting...

Journal: :Acta poloniae pharmaceutica 2013
Wojciech Pajak Elzbieta Brzezińska Cecylia Mielczarek

The article presents extended computer investigations of various sulfate derivatives of riboflavin. A number of physicochemical parameters such as total energy, binding energy and formation heat were calculated via semi-empirical methods AM1 and PM3 for the different derivatives of riboflavin. Their analysis made it possible to determine the sequence of formation of sulfate derivatives--esterif...

Journal: :Acta poloniae pharmaceutica 2008
Elzbieta Brzezińska Cecylia Mielczarek Wojciech Pajak

A number of physicochemical parameters were calculated via semi-empirical methods AM1 and PM3 for the molecule of riboflavin at various protonation states. Their analysis made it possible to determine the acidicity of appropriate groups of this compound. The sequence of protons dissociation and accepting by the neutral molecule of riboflavin was determined. This methodology may be used to study...

2013
Casper Steinmann Kristoffer L. Blædel Anders S. Christensen Jan H. Jensen

An interface between semi-empirical methods and the polarized continuum model (PCM) of solvation successfully implemented into GAMESS following the approach by Chudinov et al (Chem. Phys. 1992, 160, 41). The interface includes energy gradients and is parallelized. For large molecules such as ubiquitin a reasonable speedup (up to a factor of six) is observed for up to 16 cores. The SCF convergen...

2007
John D. Lafferty Larry A. Wasserman

Semi-supervised methods use unlabeled data in addition to labeled data to construct predictors. While existing semi-supervised methods have shown some promising empirical performance, their development has been based largely based on heuristics. In this paper we study semi-supervised learning from the viewpoint of minimax theory. Our first result shows that some common methods based on regulari...

Journal: :Physical chemistry chemical physics : PCCP 2015
Ying Huang Xiangping Zhang Yongsheng Zhao Shaojuan Zeng Haifeng Dong Suojiang Zhang

Potential applications of ILs require the knowledge of the physicochemical properties of ionic liquid (IL) mixtures. In this work, a series of semi-empirical models were developed to predict the density, surface tension, heat capacity and thermal conductivity of IL mixtures. Each semi-empirical model only contains one new characteristic parameter, which can be determined using one experimental ...

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