The problem of query selectivity estimation for database queries is critical for efficientquery execution by database management systems. A query execution method strongly depends on earlyestimated size of a query result. This estimation determines a data access method used later during thequery execution. The selectivity parameter is a fraction of table rows that satisfy a single-table querycondition. For a selection condition of a range query where an attribute has a continuous domain, theselectivity is equivalent to a definite integral form probability density function (PDF) of attribute valuesdistribution. For a compound selection condition based on many attributes we need a multidimensionalspace-efficient non-parametric estimator of multivariate PDF of attribute values distribution. A knownapproach based on Discrete Cosine Transform (DCT) spectrum as an representation of multidimensionalPDF is considered. The energy compaction property of DCT lets omit a region of spectrum coefficientswith small absolute values without significant losing an accuracy of selectivity estimation. An area ofrelevant spectrum coefficients is called a sampling zone. Results of experiments from previous worksshows that applying the reciprocal shape of the sampling zone gives the least selectivity estimation errorsubject to a predetermined size of the zone. The main result of this work is a theoretical confirmation of onlyexperimental results from previous works. The paper presents the proof of the theorem that the reciprocalshape of the sampling zone is asymptotically error-optimal. The proof is based on calculus of variationsand the isoperimetric problem.

Estymacja metodą najmniejszych kwadratów (LS) jest Jednym z najważniejszych narzędzi w analizowaniu danych geodezyjnych. Jednakże powszechne korzystanie z rej metody nie zawsze idzie w parze z pełnym uświadomieniem sobie jej podstaw. W standardowym formalizmie teorii estymacji LS w rzeczywistości istnieje kilka paradoksalnych i osobliwych zagadnień rzadko formułowanych wprost. Celem niniejszej pracy jest przedstawienie niektórych z tych zugadnień i przedyskutowanie ich konsekwencji w analizie danych gcodezyjnvch oraz problematyce estymacji parametrów. W pierwszej części pracy przedstawiony Jest alternatywny pogląd na podstawy statystyczne, które są tradycyjnie łączone z estymacją LS. W SZC7.ególności pokazano. że właściwość nieobciąźoności dla zwykłych estymatorów LS może być zastąpiona przez inne. równowazne JeJ uwarunkowanie, które powoduje, że zakres numeryczny nieznanych parametrów jest nieograniczonv. \V drugiej części pracy przedstawiono wady meiodv LS 7. czysto algebraicznego punktu widzenia. bez uwzględnienia pojęć z zakresu prot abilisryczncgo/sratysrycznego teorii estymacji. W szczególności ,, yjaśnione zostało. cło czego odnosi się 'najmnicjsz, · (least) w metodzie najmniejszych kwadratów. Z pewnością nie odnosi się cło błędów· wyznaczanych parametrów modelu. Ponadto stwierdzono, że w bielej inwersji modelu liniowego opartej na metodzie LS istnieje krytyczna zamiana pomiędzy normami euklidesowymi błędów wyznaczanych parametrów i wyrównanych residuów.

The present paper describes the results of experimental investigations of heat transfer during condensation of R134a, R404A and R407C in pipe minichannels with internal diameters 0.31-3.30 mm. The results concern investigations of the local heat transfer coefficient. The results were compared with the correlations proposed by other authors. Within the range of examined parameters of the condensation process in minichannels made of stainless steel, it was established that the values of the heat transfer coefficient may be described with Akers et al., Mikielewicz and Shah correlations within a limited range of the mass flux density of the refrigerant and the minichannel diameter. On the basis of experimental investigations, the authors proposed their own correlation for the calculation of local heat transfer coefficient.

The presence of nanoparticles in heat exchangers ascertained increment in heat transfer. The present work focuses on heat transfer in a longitudinal finned tube heat exchanger. Experimentation is done on longitudinal finned tube heat exchanger with pure water as working fluid and the outcome is compared numerically using computational fluid dynamics (CFD) package based on finite volume method for different flow rates. Further 0.8% volume fraction of aluminum oxide (Al2O3) nanofluid is considered on shell side. The simulated nanofluid analysis has been carried out using single phase approach in CFD by updating the user-defined functions and expressions with thermophysical properties of the selected nanofluid. These results are thereafter compared against the results obtained for pure water as shell side fluid. Entropy generated due to heat transfer and fluid flow is calculated for the nanofluid. Analysis of entropy generation is carried out using the Taguchi technique. Analysis of variance (ANOVA) results show that the inlet temperature on shell side has more pronounced effect on entropy generation.

As a machining technology, welding can cause serious accidents by overloading or operation mistakes. Through analyzing the causes of various welding accidents, we found that the major cause for damage imposed after welding parts are loaded is the fracture of materials. Therefore, studying the influence of welding residual stress on the fracture property of materials is of great significance. This paper applied the digital image correlation technique to study the fracture property of welding parts under the influence of welding residual stress. In addition, standard parts and welding parts were selected to carry out a contrast experiment. Room temperature tensile tests were performed on both standard parts and test pieces after residual stress measurement. Using displacement field and strain field data obtained through VIC-2D software, the stress intensity factor around the crack tip of each specimen under the conditions of small load was calculated and corresponding analysis was carried out.

In order to identify the modal parameters of civil structures it is vital to distinguish the defective data from that of appropriate and accurate data. The defects in data may be due to various reasons like defects in the data collection, malfunctioning of sensors, etc. For this purpose Exploratory Data Analysis (EDA) was engaged toenvisage the distribution of sensor’s data and to detect the malfunctioning with in the sensors. Then outlier analysis was performed to remove those data points which may disrupt the accurate data analysis. Then Data Driven Stochastic Sub-space Identification (DATA-SSI) was engaged to perform the modal parameter identification. In the end to validate the accuracy of the proposed method stabilization diagrams were plotted. Sutong Bridge, one of the largest span cable stayed bridge was used as a case study and the suggested technique was employed. The results obtained after employing the above mentioned techniques are very valuable, accurate and effective.

The article is a polemics with some traditional concepts of theories of a historical source. The Author of the article takes Marek Henrykowski's assumption of a film being a historical source as a departing point for his own vision of a metaphor of a source and further discussion with some of Hendrykowski's concepts.

The most important criteria for evaluation of building engineering is the state of indoor climate and energy consumption. Increase of the rate of energy saving resulted not only in the use of better barriers, but also building elements, such as windows, having low air leakage values. Simultaneously, in the design of new buildings and the retrofit of existing buildings, traditional structures of natural ventilation are used. In these cases, the ventilation is an important tool for a dcsiderable realization of all environmental and energy requirements. The paper presents selected results of a long-term research work. These results were obtained by questionnaires, measurements and simulations of ventilation processes in typical detached houses, blocks of flats and office buildings. The main objective of the presented paper is to demonstrate investigations and summarize a large number of results which describe the airtightness and natural ventilation on indoor environment.

Knowledge on the physicochemical properties of PM emitted from industrial installations is necessary for assessing current state of ambient air and selecting proper methods for preventing suspended PM from degrading the air quality. Similar to many other industries, fast developing ceramic tile industry releases some amounts of PM to the atmosphere. Samples of PM were taken from main technological operations of three tile manufacturing installations, located in three various plants. The collected PM was examined for granular composition, morphology, phase composition and heavy metal content by using instrumental methods.

The aim of this paper is twofold: to estimate the unsteady pressure-flow variations in gas transmission pipelines using the ensemblebased data assimilation approach and to analyse the strength of steel tubes reinforced with composite sleeves containing localized part-wall thickness loss caused by corrosion while taking into consideration a safe operating pressure of the pipeline. For a steel thin-walled cylinder containing a partwall metal loss, a flexible wrap of fibreglass as well as carbon glass with epoxy resin are determined. The strength of the repaired pipeline with two kinds of materials for sleeves is investigated taking into consideration the internal pressure at the defect location. For the case study, a section of the Yamal transit pipeline on the Polish territory is selected. The results enable pipeline operators to evaluate the strength of corroded steel pipelines and develop optimal repair activities, which are of vital importance for the maintenance and operation of underground steel networks.

The article presents the results of the second part of an eye-tracking study conducted on Polish secondary school students working with a textbook for learning English. 20 dyslexic and 20 non- dyslexic school students worked with two sets of materials that had different graphic layouts but the same content. Their eye movements were recorded. The analysed data show that the arrangement of the material and images on the textbook page influence both the way the students (especially dyslexic ones) work with the book and their results.

The start of Wolska Street, overlooking Błonia Park with the Kościuszko Mound towering over it, was an important place in the city’s structure as indicated in the competition plans for Greater Kraków from 1910. This led to the erection of formal buildings along the eastern boundary of Błonia, with the National Museum building at the forefront. In 1950, an urban-planning competition was held in relation to the planned construction of important buildings in this area. This paper presents unpublished works and the effects of decisions taken in this already forgotten competition on today’s development of the area around the square in front of the National Museum.
The goal of this paper is to present unknown competition designs dating back to mid-20th century and to indicate their impact on spatial solutions of the area at the end of Piłsudskiego Street, near the National Museum.
A comparative analysis of preserved pictorial materials and designs known to the author was used in this study. The analyses concluded that the opportunities to turn the start of Piłsudskiego Street into a nodal point in the urban plan of the city, a spot that would integrate space at both sides of Trzech Wieszczów Avenues, were not fully used. Urban analysis that also covered the area at the eastern side of the Trzech Wieszczów Avenues is a key to producing correct spatial solution for the square in front of the National Museum.

This paper discusses the protection and development of the cityscape with the use of digital techniques to determine the location of tall buildings. It presents the methodology applied while developing the 2020–2021 Composition Study of Szczecin. The study was commissioned by the City, and its results were included in the Study of Conditions and Directions for Spatial Development of Szczecin adopted in 2022. The aim was to define a framework for the development of high-rise buildings, while at the same time protect historical vistas preserved in the public consciousness. The paper discusses various methods of digital cityscape analysis based on the use of 3D city models, e.g.,Visual Protection Surface (VPS) and Visual Impact Size (VIS), which allow to indicate the maximum height of new buildings that would enable to protect strategic views and to analyse the impact of new buildings on the city space. The process resulted in the formulation of precise guidelines and the drafting of a long-term and sustainable spatial policy for the cityscape of Szczecin. The research has a universal formula and may also be applied to other cities.