natural convection heat transfer from a tube bundle in the indirect water bath heaters is investigated. a computer-code is used for the solution of the governing equations of mass, momentum and energy transfer based on the simple-c algorithm. simulations are carried out for the gas pressure station heater of kermanshah city with various tube bundle arrangements. in order to validate the numeric...

The exponent of periodicity is an important factor in estimates of complexity of word-unification algorithms. We prove that the exponent of periodicity of a minimal solution of a word equation is at most 2, where n is the length of the equation. Since the best known lower bound is 2 our upper bound is almost optimal and exponentially better than the original bound (6n) 2n4 + 2. Thus our result ...

Very recently, the second author showed that the question whether an equation over a trace monoid has a solution or not is decid-able 11,12]. In the original proof this question is reduced to the solv-ability of word equations with constraints, by induction on the size of the commutation relation. In the present paper we give another proof of this result using lexicographical normal forms. Our ...

The lower Wythoff sequence a = (a(n)) and upper Wythoff sequence b = (b(n)) are solutions of many complementary equations f(a, b) = 0. Typically, f(a, b) involves composites such as a(a(n)) and a(b(n)), and each such sequence is treated as a binary word (e.g., aa and ab). Conversely, each word represents a sequence and, as such, is a linear combination of a, b, and 1, in which the coefficients ...

The word substitutions are binary word operations which can be basically interpreted as a deletion followed by insertion, with some restrictions applied. Besides being itself an interesting topic in formal language theory, they have been naturally applied to modelling noisy channels. We introduce the concept of substitution on trajectories which generalizes a class of substitution operations. W...

In this paper, 1 we propose a novel loss function for the overall risk criterion estimation of hidden Markov models. For continuous speech recognition, the overall risk criterion estimation with the proposed loss function aims to directly maximise word recognition accuracy on the training database. We propose reestimation equations for the HMM parameters, which are derived using the Extended Ba...

We formalize the notion of a factorization of a word, a so-called F -factorization, introduced in [7] when solving some open problems on word equations. We show that most of the factorizations considered in the literature t well into that framework, and in particular that central algorithmic problems, such as the uniqueness or the synchronizability, remain polynomial time solvable for an import...

We develop techniques for learning the meanings of unknown words in context. Working within a com-positional semantics framework, we write down equations in which a sentence's meaning is some combination function of the meaning of its words. When one of the words is unknown, we ask for a paraphrase of the sentence. We then compute the meaning of the unknown word by inverting parts of the semant...

In this paper, a new technique is introduced that relaxes the HMM conditional independence assumption in a principled way. Without increasing the number of states, the modeling power of an HMM is increased by including only those additional probabilistic dependencies (to the surrounding observation context) that are believed to be both relevant and discriminative. Conditional mutual information...

The word substitutions are binary word operations which can be basically interpreted as a deletion followed by insertion, with some restrictions applied. Besides being itself an interesting topic in formal language theory, they have been naturally applied to modelling noisy channels. We introduce the concept of substitution on trajectories which generalizes a class of substitution operations. W...