One of the mathematical tools to measure the generation rate of new patterns along a sequence of symbols is the Lempel-Ziv complexity (LZ). Under additional assumptions, LZ is an estimator of entropy in the Shannon sense. Since entropy is considered as a measure of randomness, this means that LZ can be treated also as a randomness indicator. In this paper, we used LZ concept to the analysis of different flow regimes in cold flow combustor models. Experimental data for two combustor’s configurations motivated by efficient mixing need were considered. Extensive computer analysis was applied to develop a complexity approach to the analysis of velocity fluctuations recorded with hot-wire anemometry and PIV technique. A natural encoding method to address these velocity fluctuations was proposed. It turned out, that with this encoding the complexity values of the sequences are well correlated with the values obtained by means of RMS method (larger/smaller complexity larger/smaller RMS). However, our calculations pointed out the interesting result that most complex, this means most random, behavior does not overlap with the “most turbulent” point determined by the RMS method, but it is located in the point with maximal average velocity. It seems that complexity method can be particularly useful to analyze turbulent and unsteady flow regimes. Moreover, the complexity can also be used to establish other flow characteristics like its ergodicity or mixing.
Supplementing well recognised practical models of project and construction management, based on probabilistic and fuzzy events may make possible to transfer the weight of the change and extra orders assessment from the qualitative form to a quantitative one. This assessment, however, is naturally burdened with an immeasurable, subjective aspect. Elaboration of probability of occurrence in a construction project unforeseen building works requires application (in addition to the non-measureable, qualitative criteria) of measurable (quantitative) criteria which still appear during construction project implementation. In reimbursable engineering contracts, a random event described as an extra, supplementary building work has a random character and occurs with a specific likelihood. In lump sum contracts, on the other hand, such a random event has a fuzzy character and its occurrence is defined in a linear manner by the function of affiliation to the set of fuzzy events being identical with unforeseen events. The strive for quantitative presentation of criteria regarded by nature as qualitative and the intention to determine relations between them led to the application of the fuzzy sets theory to this issue. Their properties enable description of the unforeseen works of construction projects in an unambiguous, quantitative way.
Działania mające na celu poprawę efektywności energetycznej systemów zaopatrzenia w ciepło wymagają korzystania z coraz bardziej złożonych metod. Podstawowe sposoby zmniejszenia zużycia ciepła poprzez stosowanie lepszej izolacji cieplnej mają coraz bardziej ograniczone możliwości i wymagają stosunkowo dużych nakładów finansowych. Dobre efekty mogą być osiągane przez coraz lepsze dopasowanie rozwiązań technicznych, sposobów regulacji czy zasad eksploatacji źródła ciepła do warunków konkretnego obiektu zasilanego w ciepło. Wymaga to jednak zarówno badań identyfikujących skuteczność takich metod, jak i narzędzi służących do opisu wybranych elementów systemu czy jego całości. Artykuł przedstawia wyniki badań przeprowadzonych dla kotłowni gazowej zasilającej w ciepło grupę budynków mieszkalnych. Celem było zbudowanie modelu, który prognozowałby dla konkretnego dnia przedział czasowy, w którym występuje maksymalne zużycie gazu. Dysponując pomiarami zużycia gazu w kolejnych godzinach doby, zdecydowano się zbudować model prognostyczny wyznaczający tę część doby, w której takie maksimum wystąpi. W opracowanym modelu zdecydowano się zastosować procedurę lasów losowych (random forest). Do utworzenia modelu zastosowano pakiet mlr (Kassambara), w którym przeprowadzono również strojenie hiperparametrów modelu na bazie danych historycznych. W oparciu o odrębne dane dla innego okresu działania kotłowni przedstawiono wyniki oceny jego jakości. Uzyskano skuteczność niemal 44%. Strojenie modelu wpłynęło na poprawę jego zdolności predykcyjnych.
Artykuł przedstawia dorobek naukowy laureatów Nagrody Banku Szwecji im. Alfreda Nobla w dziedzinie nauk ekonomicznych przyznanej w 2019 r.: E. Duflo, A. Banerjee i M. Kremera. Omówiony został ich wkład do badań nad przyczynami i sposobami łagodzenia ubóstwa na świecie, a przede wszystkim wkład do rozwoju badań eksperymentalnych w naukach społecznych wykorzystujących schemat randomizowanych badań kontrolowanych (RCT). W tym kontekście autorzy wyjaśniają także przyczyny wzrostu popularności podejścia eksperymentalnego w ekonomii rozwoju oraz omawiają jego silne strony i ograniczenia.
The paper deals with the variability of mechanical properties of EPSTAL steel rods produced in Polish steelworks, i.e. yield stress Re, tensile strength Rm, and elongation Agt. Our study is based on fundamental engineering static room-temperature tensile tests for large series specimens which have been made by manufacturers as the part of a factory quality control. Statistical analysis of these results shows that the stressstrain relationship of steel tensile tests should be described by a one-dimensional stochastic process, and three the most important mechanical parameters, i.e. the yield stress, tensile strength, and elongation by random variables. Based on the statistical elaboration of experimental data, it was found that the yield stress and tensile strength of steel rods produced in the years 2016-2017 had the coefficients of variation of less than 3%, and there is a reasonable basis for the manufacturer to increase the characteristic value of EPSTAL steel rods yield stress by a few percentages.
A class of Xorshift Random Number Generators (RNGs) are introduced by Marsaglia. We have proposed an algorithm which constructs a primitive Xorshift RNG from a given prim- itive polynomial. We also have shown a weakness present in those RNGs and suggested its solution. A separate algorithm also proposed which returns a full periodic Xorshift generator with desired number of Xorshift operations.
Many studies on middle income trap draw attention to the product trapt hat can be expressed as the fact that countries are stuck in the production and export of unsophisticated products. In this sense, it is stated that the role of a country in the production and export of sophisticated goods is one of the determinant factors to increase the level of income. In the literature, the concept of economic complexity, which is expressed as gaining competitiveness of complex products in terms of production and export, is noteworthy in recentyears. In this framework, relationship between the per capita GDP and the economic complexity is examined with regression analysis in this study for selected countries with high-level of income. In the analysis, in which random coefficient panel regression model is applied, a significant relationship was found between the two variables for Austria, Finland, Hong Kong, Japan, Norway,Singapore and Sweden.