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Wyniki wyszukiwania dla: natural%20convection
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Novel Analytic-Numerical Model of Free Convection: with Leading Edge Considered
PublikacjaA novel solution of the free convection boundary problem is represented in analytical form for velocity and temperature for an isothermal vertical plate, as an example. These fields are built as a Taylor Series in the x coordinate with coefficients as functions of the vertical coordinate (y). We restrict ourselves by cubic approximation for both functions. The basic Navier-Stokes and Fourier-Kirchhoff equations and boundary conditions...
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The impact of natural fibers’ characteristics on mechanical properties of the cement composites
PublikacjaThe paper reviews the properties of cement composites reinforced with short fibres. The effect of natural fibres was investigated: cotton, sisal, jute, ramie, bamboo, and synthetic fibres: polymer and polypropylene. It was noticed that the fibres change the consistency of the mixture up to 15%. In the composite flexural strength tests, a change in strength by +/− 8% was observed, depending on the type of fibres used. The research...
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Deep learning-based waste detection in natural and urban environments
PublikacjaWaste pollution is one of the most significant environmental issues in the modern world. The importance of recycling is well known, both for economic and ecological reasons, and the industry demands high efficiency. Current studies towards automatic waste detection are hardly comparable due to the lack of benchmarks and widely accepted standards regarding the used metrics and data. Those problems are addressed in this article by...
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Investigation of natural frequencies of axially loaded thin-walled columns
PublikacjaThe paper deals with correlation between natural frequencies of two steel thin-walled columns and the corresponding applied load. The structures are made of cold-formed lipped channel sections. The columns lengths were assumed to follow two buckling patterns – global flexural and flexural-torsional buckling. In the thicker structure two material models were considered – linearly-elastic and elastic-perfectly plastic. Numerical...
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First natural transverse frequency of truncated cone and wedge beams
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Structure and function of natural proteins for water transport: general discussion
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Characterization of the natural chemical and osmotic environment of early wheat embryogenesis
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All-natural bio-plastics using starch-betaglucan composites
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Deep learning-based waste detection in natural and urban environments
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Recent advances in extraction and analysis procedures of natural chlorogenic acids
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Natural composites based on polysaccharide derivatives: preparation and physicochemical properties
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Clinoptilolite as a natural, active zeolite catalyst for the chemical transformations of geraniol
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Vasopressin and Its Analogues: From Natural Hormones to Multitasking Peptides
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Membrane distillation of NaCl solution containing natural organic matter
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Synthesis, physical and chemical properties of polyetherurethanes modified by natural antioxidant
PublikacjaOtrzymano nowe polieterouretany modyfikowane witaminą E. Ten naturalny przeciwutleniacz związany został z makrocząsteczkami w postaci bocznych odgałęzień poprzez wiązanie eterowe lub uretanowe, zależnie od użytego w syntezie jednego z dwóch rodzajów otrzymanych uprzednio monomerów. Polimery scharakteryzowano mierząc wytrzymałość na rozciąganie i twardość oraz absorpcję wody i oleju słonecznikowego. Odporność chemiczną badano oznaczając...
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Polyurethane Glycerolysate as a Modifier of the Properties of Natural Rubber Mixtures and Vulcanizates
PublikacjaChemical recycling of polyurethanes can be realized in several different ways, but the most important methods are glycolysis and glycerolysis. Both methods permit recovery of polyols (when the process is realized with the mass excess of depolymerizing agent) or substitutes of polyols, which contain urethane moieties in the main chains and terminate mainly in hydroxyl groups (when the process is realized with the mass excess of...
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Chemical modifications of natural oils and examples of their usage for polyurethane synthesis
PublikacjaNatural oils have been used in the production of plastics for a long time. However, the number of studies dedicated to polyurethane research has shown an increase only recently. Usually, petrochemical components are used in polyurethane synthesis. Nowadays, there have been attemptsmade to replace polyols in polyurethanes with the modified oils and other natural raw materials. It is a promising and important scenario because the...
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Spatiotemporal dynamics of the active perirheic zone in a natural wetland floodplain
PublikacjaAbstract The ecologically and biogeochemically significant perirheic zone is a part of the floodplain where waters originating from both the river and adjacent floodplain are present. In this study, we investigate the spatiotemporal dynamics of the active perirheic zone, i.e. river and floodplain waters and their transient mixing extent. This is achieved by using the Hydraulic Mixing-Cell method, a complement to a fully integrated...
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DBpedia and YAGO Based System for Answering Questions in Natural Language
PublikacjaIn this paper we propose a method for answering class 1 and class 2 questions (out of 5 classes defined by Moldovan for TREC conference) based on DBpedia and YAGO. Our method is based on generating dependency trees for the query. In the dependency tree we look for paths leading from the root to the named entity of interest. These paths (referenced further as fibers) are candidates for representation of actual user intention. The...
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Correlation between natural frequencies and buckling load in a stiffened shell
PublikacjaThe paper deals with correlation between natural frequencies and buckling load of a stiffened shell composed of corrugated sheets and vertical stiffeners (columns). The simplified shell segment represents the buckling behaviour of a whole silo with sparsely distributed columns. The paper covers variants of linear buckling anal-yses, dynamic eigenvalue analyses and geometrically non-linear analyses of a segment modelled with shell...
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The effect of mercerized sisal fibres on natural rubber composites' properties
PublikacjaW pracy omówiono wyniki badań fizyko-mechanicznych kompozytów otrzymanych z mieszanek zawierających kauczuk naturalny oraz statystycznie zdyspergowane krótkie włókno sisalowe. Włókno naturalne przed użyciem poddano merceryzacji.Otrzymane wulkanizaty poddano badaniom wytrzymałościowym w warunkach statycznych w celu określenia wpływu parametrów wulkanizacji i ilości dodanego włókna na właściwości otrzymanych produktów. Stwierdzono...
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Influence of operation of national experimental nuclear reactor on the natural environment
PublikacjaThis paper presents the impact of experimental nuclear reactor operations on the national environment, based on assessment reports of the radiological protection of active nuclear technology sources. Using the analysis of measurements carried out in the last 15 years, the trends are presented in selected elements of the environment on the Świerk Nuclear Centre site and its surroundings. In addition, the impact of research results...
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Some aspects of the constitutive modelling of natural fine grained soils
PublikacjaThe monograph deals with selected problems of the constitutive modelling of natural fine grained soils commonly known as clays. The main idea is not to propose a unified model which is capable of describing all known features of mechanical behaviour of fine grained soils. Instead, separate models are proposed describing the mechanical behaviour of heavily overconsolidated, lightly overconsolidated and normally consolidated clays....
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ASSESSMENT OF NATURAL VENTILATION SYSTEM FOR A TYPICAL RESIDENTIAL HOUSE IN POLAND
PublikacjaThe paper presents the research results of field measurements campaign of natural ventilation performance and effectiveness in a residential building. The building is located in the microclimate whose parameters differ significantly in relation to a representative weather station. The measurement system recorded climate parameters and the physical variables characterizing the air flow in the rooms within 14 days of the winter season....
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Experimental Investigation of Free Convection Heat Transfer from Horizontal Cylinder to Nanofluids
PublikacjaThe results of free convection heat transfer investigation from a horizontal, uniformly heated tube immersed in a nanofluid are presented. Experiments were performed with five base fluids, i.e., ethylene glycol (EG), distilled water (W) and the mixtures of EG and water with the ratios of 60/40, 50/50, 40/60 by volume, so the Rayleigh (Ra) number range was 3 104 Ra 1.3 106 and the Prandtl (Pr) number varied from 4.4 to 176....
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Experimental Investigations of Forced Convection of Nanofluids in Smooth, Horizontal, Round Tubes: A Review
PublikacjaA comprehensive review of published works dealing with experimental studies of forced convection heat transfer of nanofluids is presented. The survey is limited to straight, smooth, and round tubes. Moreover, only mono nanofluids exhibiting Newtonian behaviour are considered. Works on experimental research of forced convection in tubes are presented in a chronological order in the first part of the article. In this part, attention...
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Free convection of water-Al2O3 nanofluid from horizontal porous coated tube
PublikacjaNanofluids are expected to enhance heat transfer in many thermal systems. Present efforts are concentrated on boiling heat transfer of nanofluids, although single phase convection is of key importance in various appliances such as car radiators or heating systems. This paper presents experimental results of heat transfer during free convection of water-Al3O3 nanofluid from horizontal tube covered with metallic porous coating. Contrary...
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Experimental investigation of forced convection of water/EGAl2O3 nanofluids inside horizontal tube
PublikacjaIn this paper, forced convection of water/EG-Al2O3 nanofluids inside horizontal stainless steel tube is studied experimentally. As base fluid served water/EG mixture of two ratios (60:50 and 50:50). Nanoparticle mass concentrations was 0.1% or and 1%. Transition and turbulent flow regimes were tested. Average heat transfer coefficient and pressure drop values were determined for nanofluids and compared to base fluids. Deterioration...
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Free convection of water-Al2O3 nanofluid from horizontal porous coated tube
PublikacjaThe main aim of the present study was to investigate the influence of nanoparticles on heat transfer coefficients during free convection of water-Al2O3 nanofluid from horizontal porous coated tube under atmospheric pressure for nanoparticle concentration of 0.01% by weight. Contrary to published data present study concerns on free convection of nanofluids in extensive, quiescent fluid.
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EXPERIMENTAL INVESTIGATION OF FREE CONVECTION OF GLYCOL-Al2O3 NANOFLUID FROM HORIZONTAL TUBE
PublikacjaNanofluids came to be seen as a new generation of coolants, both in single- and two phase systems. Furthermore, nanofluids or nanocomposites may be used as a media in a thermal energy storage (TES) in such systems as sensible heat storage (SHS) and phase change materials (PCM). In the SHS systems the dominating mechanism of the heat transfer is natural convection. However, in the literature only a few investigations of free convection...
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Experimental investigation of forced convection of water-Al2O3 nanofluids inside horizontal tubes,
PublikacjaIn this paper, forced convection of water–Al2O3 nanofluids inside horizontal copper tube is studied experimentally. Experiments were conducted for three, i.e. 0.1%, 1% and 5% nanoparticle mass concentrations under transition and turbulent flow regimes. Average heat transfer coefficients and pressure drop values were determined and compared to distilled water. Enhancement of heat transfer for lower nanoparticle concentration and...
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Experimental investigation of free convection of glycol-Al2O3 nanofluid from horizontal tube
PublikacjaNanofluids came to be seen as a new generation of coolants, both in single- and two phase systems. Furthermore, nanofluids or nanocomposites may be used as a media in a thermal energy storage (TES) in such systems as sensible heat storage (SHS) and phase change materials (PCM). In the SHS systems the dominating mechanism of the heat transfer is natural convection. However, in the literature only a few investigations of free convection...
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Numerical and experimental investigation of thermal convection near electric devices with vertical channels
PublikacjaThis paper presents the results of numerical and experimental investigation of thermal convection near heat emitting surfaces of an electric device. For the intensification of thermal convection, special vertical channels were formed near the heat emitting surfaces of the device. An experimental test has proved that there is an optimal length of the channels – thermal convection is the most intensive then. Air velocity vectors...
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Natura a architektura - filozoficzne postawienie problemu.
PublikacjaPostęp w rozwoju cywilizacji związany z rozszerzeniem sfery ludzkiej wolności oddala nas od natury poprzez jej uprzedmiotowienie. Przyroda postrzegana estetycznie pełni w nowoczesnym społeczeństwie funkcją kompensującą te przedmiotowe do niej odniesienia co jest szczególnie widoczne w architekturze odzyskującej przyrodę jako krajobraz.
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Natural sweeteners: Sources, extraction and current uses in foods and food industries
PublikacjaFood producers have leaned towards alternative natural and synthetic sweeteners in food formulations to satisfy market demands. Even so, several synthetic sweeteners (e.g., aspartame, saccharin, sucralose) are becoming less popular due to health-related concerns, lower nutritional values, and controversies around their safety. Conversely, natural sweeteners confer favourable customer perceptions due to their association to a healthier...
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Natural carbon-based quantum dots and their applications in drug delivery: A review
PublikacjaNatural carbon based quantum dots (NCDs) are an emerging class of nanomaterials in the carbon family. NCDs have gained immense acclamation among researchers because of their abundance, eco-friendly nature, aqueous solubility, the diverse functionality and biocompatibility when compared to other conventional carbon quantum dots (CDs).The presence of different functional groups on the surface of NCDs such as thiol, carboxyl, hydroxyl,...
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Application of the Chimney Cap as a Method of Improving the Effectiveness of Natural Ventilation in Buildings
PublikacjaAdequately designed natural ventilation is the cheapest and easiest way to effectively remove indoor pollutants and keep the air inside a building fresh. A prediction of the performance and effectiveness of ventilation in order to determine the design of a ventilation system can provide real and long-term cost savings. The worst time in terms of the efficiency of natural ventilation is the spring-autumn transition period [7]. In...
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Novel Approaches of Using of Spirulina Platensis in Natural Rubber Based Composites
PublikacjaThe aim of this work was to investigate the influence of Spirulina (Spirulina platensis) as a natural filler on the curing characterization, morphology and mechanical, thermomechanical and thermal properties of natural rubber (NR) based composites. Spirulina was introduced into NR mixture in amount of 0 phr, 10 phr and 30 phr. The vulcanization process was carried out at the determined process condition by using hydraulic press...
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Seawater-mixed concretes containing natural and sea sand aggregates – A review
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Experimental Verification of Natural Vibration Models of Steel-concrete Composite Beams
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Photodegradation of 2,4-Dichlorophenol in Aqueous Systems under Simulated and Natural Sunlight
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Identification, characterization and purification of the lantibiotic staphylococcin T, a natural gallidermin variant
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Natural carbon-based quantum dots and their applications in drug delivery: A review
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Identification of Polyphenols from Coniferous Shoots as Natural Antioxidants and Antimicrobial Compounds
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Osmotic membrane distillation with continuous regeneration of stripping solution by natural evaporation
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Natural modes of an active slab microcavity with air-filled periodic inclusions
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A Formal Approach to Model the Expansion of Natural Events: The Case of Infectious Diseases
PublikacjaA formal approach to modeling the expansion of natural events is presented in this paper. Since the mathematical, statistical or computational methods used are not relevant for development, a modular framework is carried out that guides from the external observation down to the innermost level of the variables that have to appear in the future mathematical-computational formalization. As an example we analyze the expansion of Covid-19....
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Features of ammonium-ions sorption by natural zeolites under dynamic conditions.
PublikacjaW pracy przedstawiono: charakterystykę naturalnych zeolitów, obszar ich praktycznego wykorzystania w zakresie adsorpcyjnego usuwania niektórych zanieczyszczeń z wód oraz wyniki badań procesu adsorpcji jonów amoniowych z wodnych roztworów modelowych (w układzie dynamicznym) na wybranych zeolitach naturalnych.
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Natural convective heat-transfers from an isothermal horizontal hemispherical cavity
PublikacjaPrzedstawiono rozwiązanie analityczne oraz wyniki badań eksperymentalnych i numerycznych konwekcyjnej wymiany ciepła od poziomej izotermicznej kulistej wklęsłej powierzchni.
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Reinforcing and plasticizing effects of reclaimed rubber on the vulcanization and properties of natural rubber
PublikacjaThe production of high-added value reclaimed rubber (RR) is of great signifi-cance for the sustainability of rubber industries. To green recycle waste rub-bers and broaden the application of RR, a RR material with potentialreinforcing and plasticizing effects on nature rubber (NR) composites are pre-pared by a thermo-oxidative reclamation process. The reclamation degree ofRR is controlled by adjusting the content of soybean oil....