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Wyniki wyszukiwania dla: flexible polyurethane foams
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Metal Foams as Novel Catalyst Support in Environmental Processes
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On the effective properties of foams in the framework of the couple stress theory
PublikacjaIn the framework of the couple stress theory, we discuss the effective elastic properties of a metal open-cell foam. In this theory, we have the couple stress tensor, but the microrotations are fully described by displacements. To this end, we performed calculations for a representative volume element which give the matrices of elastic moduli relating stress and stress tensors with strain and microcurvature tensors.
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Comparative analysis of the flow control over a circular cylinder with detached flexible and rigid splitter plates
PublikacjaA comparative study is performed on a circular cylinder with both flexible and rigid splitter plates (SPs). This study has the novelty of using single and dual detached SPs located downstream of the cylinder. The dimensionless gap distance between the first splitter plate and the cylinder as well as the distance between the SPs are varied. The strain of flexible SPs can be used for energy harvesting from the flow. Therefore, a...
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Numerically efficient algorithm for compact microwave device optimization with flexible sensitivity updating scheme
PublikacjaAn efficient trust-region algorithm with flexible sensitivity updating management scheme for electromagnetic (EM)-driven design optimization of compact microwave components is proposed. During the optimization process, updating of selected columns of the circuit response Jacobian is performed using a rank-one Broyden formula (BF) replacing finite differentiation (FD). The FD update is omitted for directions sufficiently well aligned...
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Vibration surveillance for efficient milling of flexible details fixed in adjustable stiffness holder
PublikacjaThe paper presents the results of research related to the possibility of using an intelligent workpiece holder with adjustable stiffness, during end milling process. Machining a one side supported flexible workpiece will be performed with constant spindle speed and feed speed. In order to avoid hazardous vibration, stiffness of the especially designed spring (mounted in a workpiece holder) will be modified off-line. In order to...
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Single-phase product obtained via crude glycerine depolymerisation of polyurethane elastomer: structure characterisation and rheological behaviour
PublikacjaPolyurethane recycling is a topic of growing interest due to the increasing amount of polyurethanewaste. The main purpose of polyurethane feedstock recycling is to recover the starting polyol, a valuable material. In thiswork, amethod of polyurethane thermo-chemical recycling, glycerolysisbymeansof crude glycerine, is proposed. Themaineffort is focusedonthe employment of crude glycerine without purification from biodiesel production...
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Effect of kenaf fibre modification on morphology and mechanical properties of thermoplastic polyurethane materials
PublikacjaThe presented study examined the morphology and mechanical properties of biocomposites obtained from kenaf natural fibre and thermoplastic polyurethane. Kenaf was modified using various methods, namely: acetylation, blocked isocyanate, maleic anhydride and permanganate treatment. Those methods and ways of carrying out of surface modifications were not studied before on kenaf/thermoplastic polyurethane composites. Different fibre...
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Morphology, Mechanical and Thermal Properties of Thermoplastic Polyurethane Containing Reduced Graphene Oxide and Graphene Nanoplatelets
PublikacjaPolyurethane/graphene nanocomposites were synthesized using commercial thermoplastic polyurethane (TPU, Apilon 52DE55), and two types of graphene derivatives: graphene nanoplatelets (GNP) and reduced graphene oxide (RGO). Fourier Transformation Infrared Spectroscopy Fourier Transformation Infrared Spectroscopy (FTIR) spectroscopy, TEM, and SEM microscopy and XRD techniques were used to chemically and structurally characterize GNP...
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Evaluation of the glycerolysis process and valorisation of recovered polyol in polyurethane synthesis
PublikacjaIn this study, the glycerolysis of polyurethane (PU) foam and the applicability of obtained glycerolysate (GLY) for cast PUs were investigated. It was found that crude glycerine with purity grade of 84% might be successfully used for the glycerolysis. The optimal conditions were determined as follows: reaction time of 60 min at 220 °C using dibutyltin dilaurate catalyst (0.5%). Moreover, the purification of GLY by means of liquid-liquid...
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VIBRATION SURVEILLANCE DURING MILLING OF FLEXIBLE DETAILS WITH A USE OF THE ACTIVE OPTIMAL CONTROL
PublikacjaThe main goal of modern machining operations is to achieve increasingly better performance. High Speed Machining and/or High Performance Cutting, despite a lot of advantages, have also some drawbacks, for example, a possibility of losing stability and development of self-excited chatter vibration. This paper presents an approach of vibration surveillance during high speed milling with a use of active optimal control. Non-stationary...
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The rigid and flexible road pavements in terms of life cycle costs
PublikacjaThe cost of road pavement construction, its durability and reliability depends on many factors, including: the scope and detail of the technical design, quality of work but also the scope of works related to its maintenance, conservation and operation. Determining the amount of rational expenses, in terms of the life cycle cost of the pavement, requires determination and consideration of the above issues, already at the planning...
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Fabrication of Composite Polyurethane/Hydroxyapatite Scaffolds Using Solvent-Casting Salt Leaching Technique
PublikacjaScaffolds are porous three-dimensional structures which are used to fill bone losses and make them possible to cells to grow. Many different structural and biological properties are required from them: porosity, mechanical strength and biocompability. The present research is aimed at development of composite polyurethane/hydroxyapatite scaffolds by using the solvent-casting salt leaching method. The SEM examinations were applied...
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A mathematical model of rheological behavior of novel bio-based isocyanate-terminated polyurethane prepolymers
PublikacjaIn this paper, the results of rheological study on isocyanate-terminated polyurethane prepolymers, containing modified soybean oil residues incorporated into the chemical structure are described. Isocyanate-terminated prepolymers were synthesized from 4,4′-diphenylmethane diisocyanate and the mixture of hydroxylated soybean oil and commercial polyether. The measurements were performed by using rotary rheometer R/S-CPS+ (Brookfield,...
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Optimal spindle speed determination for vibration reduction during ball-end milling of flexible details
PublikacjaIn the paper a method of optimal spindle speed determination for vibration reduction during ball-end milling of flexible details is proposed. In order to reduce vibration level, an original procedure of the spindle speed optimisation, based on the Liao–Young criterion, is suggested. As the result, an optimal, constant spindle speed value is determined. For this purpose, on-stationary computational model of machining process is...
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Characteristics of the conductivity of polyurethane nanocomposite
PublikacjaW opracowaniu tym przedstawiono właściwości mechaniczne oraz przewodnictwo jonowe otrzymanych nanokompozytów poliuretanowych. KOmpozyty te były otrzymane przy wykorzystaniu wytłaczarki dwuślimakowej. POddano je badaniom wytrzymałościowym, spektroskopii impedancyjnej, spektroskopii w podczerwieni oraz badaniom dynamiczno - mechanicznym (DMA)
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Shape-Memory Polyurethane Polymers
PublikacjaPolyurethanes (PUs) are one of the most widely used polymers in research and industry. They can be synthesized from chemical sources and natural sources. PUs are a very useful class of polymers and exhibit many desirable properties that can be exploited in various applications. PUs are formed by the reaction between polyols and isocyanates. A wide variety of polyols and isocyanates are available for synthesis, and hence we can...
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Nanosize effect of clay mineral nanoparticles on the drug diffusion processes in polyurethane nanocomposite hydrogels
PublikacjaStudies of swelling and release of naproxen sodium (NAP) solution by polyurethane nanocomposite hydrogels containing Cloisite® 30B (organically modified montmorillonite (OMMT)) have been performed. Polyurethane nanocomposite hydrogels are hybrid, nontoxic biomaterials with unique swelling and release properties in comparison with unmodified hydrogels. These features enable to use nanocomposite hydrogels as a modern wound dressing....
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Unified and flexible way to the organizations resources
PublikacjaZaprezentowano porównanie różnych zasobów organizacji. zasoby podzielono na cztery grupy: informacyjne, finansowe, techniczne i ludzkie, dla których przedstawiono cechy wspólne i różnice. na podstawie tego zestawienia zaproponowano taką organizację danych, aby różne zasoby opisać w jednolity sposób. dzieki takiej organizacji danych mozliwe jest stworzenie konfigurowalnych, elastycznych komponentów, które umożliwią obsługę dowolnych...
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Vibration surveilance for milling of a flexible workpiece
PublikacjaPraca przedstawia przypadek nadzorowania drgań podczas frezowania szybkościowego przedmiotów podatnych z wykorzystaniem aktywnego sterowania optymalnego. System sterowania zawiera czujniki i wzbudniki piezoelektryczne, montowane na powierzchni przedmiotu obrabianego. Do opisu dynamiki układu sterowanego wykorzystano współrzędne hybrydowe. Skuteczność nadzorowania potwierdziły wyniki symulacji komputerowych oraz badań eksperymentalnych.
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Quality control in flexible manufacturing cell.
PublikacjaPublikacja dotyczy procesu produkcyjnego w środowisku komputerowo zintegrowanego wytwarzania. Ukazuje ona aspekty kontroli jakości wykonania części na różnych etapach procesu wytwórczego. W celu dokonania szczegółowej analizy problemu zebrano dane o jakości wykonania części na poszczególnych poziomach wytwarzania. Analizy dowiodły, że jakość wykonania części zależy od jakości użytych narzędzi a sterowanie nią wymaga optymalizacj...
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Effect of Variation of Hard Segment Content and Graphene-Based Nanofiller Concentration on Morphological, Thermal, and Mechanical Properties of Polyurethane Nanocomposites
PublikacjaThis study describes the development of a new class of high-performance polyurethane elastomer nanocomposites containing reduced graphene oxide (RGO) or graphene nanoplatelets (GNP). Two types of polyurethane elastomers with different contents of hard segments (HS) were used as a polymer matrix. The developed nanocomposites were characterized by thermal analysis (DSC, TG), dynamic mechanical testing (DMA), hardness testing, mechanical...
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Modelling and Simulation of a New Variable Stiffness Holder for Milling of Flexible Details
PublikacjaModern industry expectations in terms of milling operations often demand the milling of the flexible details by using slender ball-end tools. This is a difficult task because of possible vibration occurrence. Due to existence of certain conditions (small depths of cutting, regeneration phenomena), cutting process may become unstable and self-excited chatter vibration may appear. Frequency of the chatter vibration is close to dominant...
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Thermo-Chemical Decomposition Study of Polyurethane Elastomer Through Glycerolysis Route with Using Crude and Refined Glycerine as a Transesterification Agent
PublikacjaDue to the increasing amount of polyurethane waste, chemical recycling of these materials is a topic of growing interest for many researchers. The primary pur- pose of polyurethane feedstock recycling is to recover the starting polyol. In this study glycerolysis using glycerine from two sources and two purity grades is proposed as a method of chemical recycling. The main effort of this paper focuses on the employment of commercial...
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Preparation and Properties of Thermoplastic Polyurethane Composites Filled with Powdered Buckwheat Husks
PublikacjaBio-based fillers for the polymer composites are still interesting from the scientific and industrial point of view, due to their low cost and renewable nature. In this work partially green composites were obtained by the mixing of thermoplastic poly(ester-urethane) with the unmodified and modified (by acetylation) grinded buckwheat husks. Obtained biocomposites were characterized in the terms of their chemical structure (FTIR),...
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Synthesis and characterization of biopolyols through biomass liquefaction of wood shavings and their application in the preparation of polyurethane wood composites
PublikacjaThe sustainability of production systems in wood processing, wood industry, and wooden waste disposal is an important issue for European industry and society. Proper development of products based on renewable wood resources gives an opportunity to provide materials with long-term environmental, social, and economic sustainability. This study aims to establish a new way of forestry and agricultural waste materials utilization by...
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Rheological characteristics of oligomeric semiproducts gained via chemical degradation of polyurethane foam using crude glycerin in the presence of different catalysts
PublikacjaPolyurethane (PU) recycling is a topic of growing interest due to the increasing amount of polyurethane waste. The main purpose of polyurethane chemical recycling is to recover the starting polyol. In this study, a method of polyurethane thermochemical recycling, glycerolysis by means of crude glycerin, is proposed. This work presents a comparative study of commercial catalysts used in order to accelerate the decomposition process,...
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Polyurethanes modified with natural polymers for medical application. Part I. Polyurethane/chitosan and polyurethane/collagen
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Polyurethane-wood composites (PU-WC) as a method of wood waste management
PublikacjaIn recent years, due to the progressive environmental degradation and increase of environmental awareness, the sustainability of production systems in wood processing, the wood industry, and wood waste management is a crucial issue for European industry and society. Consequently, the problem of generating wood-like waste and the associated risks has become an increasingly noticeable challenge for science. Although various methods...
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Validation of polyurethane-wood composites properties
Dane BadawczeThis study focuses on the development of the PU-WC manufacturing method, the determination of properties of this type of composite, and the indication of its potential application. The mechanical properties of PU-WC were characterized by flexural tests. To determine the thermal properties, dynamic mechanical analysis (DMA) and thermogravimetric analysis...
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Vibration Surveillance System with Variable Stiffness Holder for Milling Flexible Details
PublikacjaEfficient milling of the flexible details (i.e. rotor blades, thin-walled elements) using slender ball-end tools is a difficult task due to possibility of vibration occurrence. Because of the existence of certain conditions (small depths of cutting, regeneration phenomena), cutting process may lose stability and self-excited chatter vibration may appear. Frequency of the chatter vibration is close to dominant natural frequency...
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Tuning the Laser-Induced Processing of 3D Porous Graphenic Nanostructures by Boron-Doped Diamond Particles for Flexible Microsupercapacitors
PublikacjaCarbon (sp3)-on-carbon (sp2) materials have the potential to revolutionize fields such as energy storage and microelectronics. However, the rational engineering and printing of carbon-on-carbon materials on flexible substrates remains a challenge in wearable electronics technology. This study demon-strates the scalable fabrication of flexible laser-induced graphene (LIG)-boron doped diamond nanowall (BDNW) hybrid nanostructures...
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INTERNATIONAL JOURNAL OF FLEXIBLE MANUFACTURING SYSTEMS
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Global Journal of Flexible Systems Management
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A Comprehensive Review of Reactive Flame Retardants for Polyurethane Materials: Current Development and Future Opportunities in an Environmentally Friendly Direction
PublikacjaPolyurethanes are among the most significant types of polymers in development; thesematerials are used to produce construction products intended for work in various conditions. Nowa-days, it is important to develop methods for fire load reduction by using new kinds of additivesor monomers containing elements responsible for materials’ fire resistance. Currently, additiveantipyrines or reactive flame retardants can be used during...
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Toughness augmentation by fibrillation and yielding in nanostructured blends with recycled polyurethane as a modifier
PublikacjaIn the present paper, we have carefully investigated the morphology and fracture mechanism of the recycled polyurethane (RPU) /epoxy blend system. The second phase (RPU) added to the epoxy resin has a positive effect on the overall mechanical properties. Interestingly, the recycled polymer has a remarkable effect on the fracture toughness of epoxy resin. The mechanism behind the fracture toughness improvement up on the addition...
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Morphology of bio-based polyurethane composites filled by mer-cerized or silanized natural fibres
PublikacjaBio-composites are materials which possess unique properties and undergo biodegra-dation under specific conditions. Bio-composites belong to the group of materials produced with the use of renewable raw materials. They contain reinforcement, mainly in the form of natural fiber, which has high stiffness and resistance; filler powders are less frequently used. Significant features of natural fibers are elongation, density, thermal...
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A novel approach in wood waste utilization for manufacturing of catalyst-free polyurethane-wood composites (PU-WC)
PublikacjaIn recent decades, due to the increase in environmental awareness and noticeable environmental degradation, the area of wood waste management has attracted increasing attention. The purpose of this study is to develop a new type of highly filled polyurethane wood-composite (PU-WC) by the utilization of large amount of wood wastes without addition of a catalyst. Although wood-plastic composites (WPCs) are widely known, there is...
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Fabrication of polyurethane and polyurethane based composite fibres by the electrospinning technique for soft tissue engineering of cardiovascular system
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Thermal-Resistant Polyurethane/Nanoclay Powder Coatings: Degradation Kinetics Study
PublikacjaIn the present study, thermal degradation kinetics of polyurethane (PU) powder coatings reinforced with organo-modified montmorillonite (OMMT) was investigated. PU nanocomposites were prepared in different concentrations of 1, 3, and 5 wt.% of OMMT via the extrusion method. The microstructure of the nanocomposites was observed by scanning electron microscope (SEM) illustrating uniform dispersion of OMMT nano-clay platelets in the...
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The structure and conductivity of solid polyurethane electrolyte
PublikacjaPrzedstawiono badania właściwości i struktury stałych elektrolitów poliuretanowych. Otrzymano je z prepolimeru zsyntezowanego z MDI oraz PTMG. Jako przedłużacz łańcucha wykorzystano butanodiol. W celu poprawy przewodnictwa domieszkowano poliuretan solami LiClO4 lub LiCl, które wprowadzono za pomocą wytłaczarki dwuślimakowej. Otrzymane elektrolity poddano badaniom: wytrzymałościowym, twardości, spektroskopii FTIR oraz przewodnictwa...
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The structure and conductivity of solid polyurethane electrolytes
PublikacjaPrzedmiotem badań były stałe elektrolity poliuretanowe otrzymane w wyniku syntezy MDI, PTMO, BD oraz TG z DMPA. Domieszkowanie LiCl zostało wykonane przy zastosowaniu przedłużacza. Badano przewodnictwo jonowe otrzymanych elektrolitów stałych przy użyciu technik stało i zmiennoprądowych. Przedstawiono również wyniki badań z wykorzystaniem technik mikroskopii elektronowej oraz FTIR-ATR.
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Versatile Unsupervised Design of Antennas Using Flexible Parameterization and Computational Intelligence Methods
PublikacjaDeveloping contemporary antennas is a challenging endeavor that requires considerable engineering insight. The most laborious stage is to devise an antenna architecture that delivers the required functionalities, e.g., multiband operation. Iterative by nature (hands-on topology modifications, parametric studies, trial-and-error geometry selection), it typically takes many weeks and requires considerable engagement from a human...
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Strontium-based nanosized phosphates as anticorrosive fi llers of epoxy and polyurethane coating compositions
PublikacjaAnticorrosive epoxy and polyurethane coatings were compounded using zinc-free nanosized phosphates of strontium (SP) or strontium and aluminum (SAP). For comparison, a nanosized calcium aluminum ammonium phosphate (CAP) and a microsized zinc phosphate (ZP) were tested. Results of salts spray and cyclic corrosion tests revealed better anticorrosive properties of the SAP-based coatings...
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The paradigm change of flexible production systems desing
PublikacjaNiniejszy artykuł pokazuje zmiany paradygmatu projektowania i eksploatacji elastycznych systemów produkcyjnych, na przykładzie różnych modeli systemów nowej generacji NGMS (Next Generation Manufacturing System). Dokonano analizy porównawczej wybranych rozwiązań w przedmiotowym obszarze, formułując prognozy rozwojowe w oparciu o zaproponowane megatrendy rozwojowe: miniaturyzacji, sieciowości (networking), mobilności, i wirtualizacji....
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Quality inspection system in flexible manufacturing cell.
PublikacjaPublikacja dotyczy struktury procesu produkcyjnego w środowisku komputerowo zintegrowanego wytwarzania (computer integrated manufacturing - CIM). Ukazuje ona aspekty kontroli jakości wykonania części na różnych etapach procesu wytwórczego, podkreślając jego istotność. W celu dokonania szczegółowej analizy problemu zebrano dane o jakości wykonania części na poszczególnych poziomach wytwarzania. Analizy dowiodły, że jakość wykonania...
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Adaptive systems for process control in flexible manufacturing.
PublikacjaW artykule przedstawiono koncepcyjne studia dla modelu sterowania dynamicznego elastycznym gniazdem obróbkowym. Analizowane gniazdo obróbkowe, zorientowane było na produkcję jednostkową i małoseryjną oraz składało się z trzech maszyn: tokarki CNC, frezarki CNC i maszyny pomiarowej.
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High-Power Jamming Attack Mitigation Techniques in Spectrally-Spatially Flexible Optical Networks
PublikacjaThis work presents efficient connection provisioning techniques mitigating high-power jamming attacks in spectrally-spatially flexible optical networks (SS-FONs) utilizing multicore fibers. High-power jamming attacks are modeled based on their impact on the lightpaths’ quality of transmission (QoT) through inter-core crosstalk. Based on a desired threshold on a lightpath’s QoT, the modulation format used, the length of the path,...
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The Effect of Flexible Pavement Mechanics on the Accuracy of Axle Load Sensors in Vehicle Weigh-in-Motion Systems
PublikacjaWeigh-in-Motion systems are tools to prevent road pavements from the adverse phenomena of vehicle overloading. However, the effectiveness of these systems can be significantly increased by improving weighing accuracy, which is now insufficient for direct enforcement of overloaded vehicles. Field tests show that the accuracy of Weigh-in-Motion axle load sensors installed in the flexible (asphalt) pavements depends on pavement temperature...
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Effect of bio-based components on the chemical structure, thermal stability and mechanical properties of green thermoplastic polyurethane elastomers
PublikacjaIt seems to be obvious that conditions changes during polyols synthesis have impact on the polyols properties. Even the chemical formula is the same or similar, physicochemical properties and also molecular weight of polyols might be different and are significant in term of future polyurethanes properties and processing. In this work, fully bio-based poly(propylene succinate)s synthesized at different temperature conditions were...
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Timber-frame house resistant to dynamic loads - analysis of wall panel filled with polyurethane foam
PublikacjaThe present study shows the experimentally and numerically determined response of a single timber-frame house wall panel filled with polyurethane (PU) foam under dynamic loads. The harmonic tests were conducted for the following frequencies: 0.5 Hz, 1.0 Hz, 2.0 Hz and 5.0 Hz for various values of the specified displacement. Based on the results of the comparison between the experimental tests and the numerical analyses, the numerical...