Benchmarking Hashing Algorithms for Load Balancing in a Distributed Database Environment

Modern high load applications store data using multiple database instances. Such an architecture requires data consistency, and it is important to ensure even distribution of data among nodes. Load balancing is used to achieve these goals. Hashing is the backbone of virtually all load balancing systems. Since the introduction of classic Consistent Hashing, many algorithms have been devised for this purpose. One of the purposes of the load balancer is to ensure storage cluster scalability. It is crucial for the performance of the whole system to transfer as few data records as possible during node addition or removal. The load balancer hashing algorithm has the greatest impact on this process. In this paper we experimentally evaluate several hashing algorithms used for load balancing, conducting both simulated and real system experiments. To evaluate algorithm performance, we have developed a benchmark suite based on Unidata MDM~ -- a scalable toolkit for various Master Data Management (MDM) applications. For assessment, we have employed three criteria~ -- uniformity of the produced distribution, the number of moved records, and computation speed. Following the results of our experiments, we have created a table, in which each algorithm is given an assessment according to the abovementioned criteria

Review of Julia Lavid-López, Carmen Maíz-Arévalo and Juan Rafael Zamorano-Mansilla.2021. Corpora in Translation and Contrastive Research in the Digital Era.

publishedVersionNon peer reviewe

Mind the source data! : Translation equivalents and translation stimuli from parallel corpora

Statements like ‘Word X of language A is translated with word Y of language B’ are incorrect, although they are quite common: words cannot be translated, as translation takes place on the level of sentences or higher. A better term for the correspondence between lexical items of source texts and their matches in target texts would be translation equivalence (Teq). In addition to Teq, there exists a reverse relation—translation stimulation (Tst), which is a correspondence between the lexical items of target texts and their matches (=stimuli) in source texts. Translation equivalents and translation stimuli must be studied separately and based on natural direct translations. It is not advisable to use pseudo-parallel texts, i.e. aligned pairs of translations from a ‘hub’ language, because such data do not reflect real translation processes. Both Teq and Tst are lexical functions, and they are not applicable to function words like prepositions, conjunctions, or particles, although it is technically possible to find Teq and Tst candidates for such words as well. The process of choosing function words when translating does not proceed in the same way as choosing lexical units: first, a relevant construction is chosen, and next, it is filled with relevant function words. In this chapter, the difference between Teq and Tst will be shown in examples from Russian–Finnish and Finnish–Russian parallel corpora. The use of Teq and Tst for translation studies and contrastive semantic research will be discussed, along with the importance of paying attention to the nature of the texts when analysing corpus findings.acceptedVersionPeer reviewe

Corpus-Based Analysis of Russian Translations of Animal Farm by George Orwell

The phenomenon of multiple translations of same classical works has been discussed extensively since 18th century. The dominant approach however is to study retranslating as a cultural, not a linguistic phenomenon. For unknown reasons, little use has been made of corpus data in research on this topic, although corpora of retranslated texts would seem to be a natural source of empirical data. Studying multiple translations with the help of corpus-based methods makes it possible to obtain the general picture of the data and to find its critical points. The quantitative data can be used for developing criteria for evaluation of the texts. In this paper, six Russian translations of George Orwell's Animal Farm are studied. The translations are compared against an unedited machine translation. A multidimensional scaling of the frequency-list-based distance matrix was performed. The analysis demonstrated that the most frequently republished translations are the most distant from the MT. The keyword analysis of the translations confirmed the findings of the MDS analysis and gave concrete clues on the lexical items typical for certain translations.acceptedVersionPeer reviewe

The Walker Function

The special function (the Walker function) and its derivatives are important for the description of near-wall turbulent flows. This article gives exact expressions for these functions, based on original identities for the hypergeometric functions 1F1 and pFp . We also introduce a new initial value problem that generates interpolating functions for (the Walker function) and its derivatives.Indisponível

The drag coefficient of a sphere: An approximation using Shanks transform

An accurate model for the drag coefficient (CD) of a falling sphere is presented in terms of a non-linear rational fractional transform of the series of Goldstein (Proc. Roy. Soc. London A, 123, 225-235, 1929) to Oseen's equation. The coefficients of the six polynomial terms are improved through a direct fit to the experimental data of Roos and Willmarth (AIAA J., 9:285-290, 1971). The model predicts CD up to Reynolds number 100,000 with a standard deviation of 0.04. Results are compared with eight different formulations of other authors.Indisponível

Feasible domain of Walker's unsteady wall-layer model for the velocity profile in turbulent flows

The present work studies, in detail, the unsteady wall-layer model of Walker et al. (1989, AIAA J., 27, 140 – 149) for the velocity profile in turbulent flows. Two new terms are included in the transcendental non-linear system of equations that is used to determine the three main model parameters. The mathematical and physical feasible domains of the model are determined as a function of the non-dimensional pressure gradient parameter (p+). An explicit parameterization is presented for the average period between bursts (T+B), the origin of time (t+0) and the integration constant of the time dependent equation (A0) in terms of p+. In the present procedure, all working systems of differential equations are transformed, resulting in a very fast computational procedure that can be used to develop real-time flow simulators.O presente trabalho estuda em detalhe o modelo parietal transiente de Walker et al. (1989, AIAA J., 27, 140-149) para perfis de velocidade em escoamentos turbulentos. Dois novos termos são adicionados ao sistema transcendental não linear de equações que é utilizado para determinar os três principais parâmetros do modelo. Os domínios matemático e físico de validade do modelo são determinados como uma função do parâmetro gradiente de pressão adimensional (p+). Uma parametrização explícita em termos de p+ é apresentada para o período médio entre eventos (T+B), para a origem do tempo (t+0) e para a constante de integração (A0) da equação dependente do tempo. Na presente análise, todos os sistemas de equações diferenciais são transformados, resultando em um procedimento computacional rápido que pode ser utilizado para o desenvolvimento de simuladores em tempo real

Physical degrees of freedom in stabilized brane world models

We consider brane world models with interbrane separation stabilized by the Goldberger-Wise scalar field. For arbitrary background, or vacuum configurations of the gravitational and scalar fields in such models, we construct the second variation Lagrangian, study its gauge invariance, find the corresponding equations of motion and decouple them in a suitable gauge. We also derive an effective four-dimensional Lagrangian for such models, which describes the massless graviton, a tower of massive gravitons and a tower of massive scalars. It is shown that for a special choice of the background solution the masses of the graviton excitations may be of the order of a few TeV, the radion mass of the order of 100 GeV, the inverse size of the extra dimension being tens of GeV. In this case the coupling of the radion to matter on the negative tension brane is approximately the same as in the unstabilized model with the same values of the fundamental five-dimensional energy scale and the interbrane distance.Comment: 17 pages, LaTeX, corrected typos, amended the normalization constants of the scalar modes and their coupling constants to matte