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Search results for: SURFACE FATIQUE STRENGTH
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Drill holes decrease cancellous bone strength: A comparative study of 33 paired osteoporotic human and 9 paired artificial bone samples
PublicationThis study was designed to compare compressive strength of cancellous bone retrieved from the femoral head in a specimen with and without guide wire hole, with comparison to synthetic bone samples. Femoral heads retrieved from 33 patients who sustained femoral neck fractures and underwent hip arthroplasty were cut into cuboids leaving two matching samples from the same femoral head. Similar samples were prepared from synthetic femurs....
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Compressive Strength and Leaching Behavior of Mortars with Biomass Ash
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Shear Strength of Organic Soils Modified by Mineral Materials
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Hygrothermal and strength properties of cement mortars containing cenospheres
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Porosimetric, Thermal and Strength Tests of Aerated and Nonaerated Concretes
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A note on the strength and minimum color sum of bipartite graphs
PublicationSiłą grafu G nazywamy najmniejszą liczbę całkowitą s, taką że istniej pokolorowanie grafu G, o minimalnej sumie przy użyciu kolorów {1,...,s}. W pracy pokazano, że w grafach dwudzielnych stopnia D zachodzi oszacowanie s <= ceil(D/2) + 1. Z obserwacji tej wynika algorytm wielomianowy do obliczania siły i sumy chromatycznej w grafach dwudzielnych stopnia co najwyżej 4.
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Hydrogen degradation of high-strength weldable steels in seawater
PublicationOceniono podatność na niszczenie wodorowe stali spawalnych o wysokiej wytrzymałości przy obciążeniach monotonicznie rosnących. Badano dwa gatunki stali ulepszonych cieplnie i ich złącza spawane. Przeprowadzono próby rozciągania z małą prędkością odkształcania w wodzie morskiej przy polaryzacji katodowej. Wykonano próby przenikania wodoru metodą Devanathana-Stachurskiego.
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Hydrogen delayed cracking of high-strength weldable steels
PublicationOceniano podatność na niszczenie wodorowe stali 14HNMBCu o wysokiej wytrzymałości i jej połączeń spawanych przy obciążeniu stałym w wodzie morskiej. Badania przeprowadzono w powietrzu, oraz w środowisku wody morskiej przy potencjale korozyjnym i przy polaryzacji katodowej. Obecność lub brak opóźnionych pęknięć próbek z karbem przyjęto za miarę odporności na niszczenie wodorowe przy stałym obciążeniu.
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Selected problems concerning strength of a floating dock with roof
PublicationW pracy przedstawiono modele i wyniki analizy wytrzymałości konstrukcji zadaszonego doku pływającego. Obliczono, że ścianki wiązarów zadaszenia, aby mogły przenieść obciążenia środowiskowe, muszą mieć grubość 24 mm. Ciężkie przesuwne segmenty zadaszenia generują w dennikach pontonu doku naprężenia sięgające 25% wartości dopuszczalnych. Wytężenie konstrukcji pontonu doku i podbudowy, obciążonych ciężarem zadaszenia i dokowanego...
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The Acid Strength of the Lewis‐Brønsted Superacids – A QSPR Study
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Hydrogen degradation of high strength low alloyed steels.
PublicationBadano wpływ polaryzacji katodowej na własności stali węglowej, stali o podwyższonej i wysokiej wytrzymałości metodą stałego powolnego odkształcania.Stwierdzono, że stopień kruchości wodorowej każdej z badanych stali zależał od stężenia wodoru dyfuzyjnego.
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Ultimate strength analysis of bulk carriers corrugated bulkheads
PublicationPrzedstawiono rozważania i obliczenia, których celem była ocena jakości standardu wytrzymałości grodzi falistych masowców, wprowadzonego w 1998 r. przez IACS i wdrożonego do konwencji SOLAS. Wykonane nieliniowe obliczenia MES nośności granicznej zginanych fal grodzi wykazują, że standard ten jest zbyt optymistyczny.
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Strength analysis of container ship subjected to torsional loading
PublicationThe objective of this work is to investigate the torsional response of a container ship, with particular consideration of the warping effect. Two different models are investigated. In the first case, the full length model of a ship is analyzed and a distributed load is applied with the use of a novel approach. The model is supported in the torsional centre of the cross-section, which is derived analytically. In the second case,...
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Strength parameters of masonry walls in modelling historic constructions
PublicationThe paper presents the determination of the basic material properties of a historic brickwork. Experimental studies were used to identify the basic material properties of bricks. The mechanical properties of the masonry, as an orthotropic homogenized material, were calculated. Then, numerical simulations using the Finite Element Method (FEM) were performed to verify the experimental outcomes. Macromodels with element sizes of 40,...
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Testing of fatigue strength limit of slide bearing materials
PublicationPrzedstawiono wyniki badań wytrzymałości zmęczeniowej wybranych trójwarstwowych łożysk cienkościennych. Zaprezentowano zdjęcia typowych pęknięć zmęczeniowych warstwy stopu łożyskowego. Obliczono i oceniono krytyczne wartości naprężeń stycznych warstwy ślizgowej.
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On a threshold induced bias in fish target strength estimation.
PublicationPrzedstawiono statystyczny opis zjawiska wpływu progu rejestracji ech od ryb na estymatę siły celu ryb. Pokazano sposób korekcji wykorzystujący zależności pomiędzy funkcjami rozkładu prawdopodobieństwa poziomu echa i charakterystyki wiązki. Przedstawiono wyniki symulacji.
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Influence of bulk solids on the buckling strength of silo shells.
PublicationW artykule przedstawiono wyniki numerycznej nieliniowej analizy wyboczenia powłok silosowych pustych i wypełnionych materiałem sypkim. Obliczenia wykonano dla różnych imperfekcji w powłoce. Wyniki teoretyczne porównano z wynikami doświadczalnymi wykonanymi w Uniwersytecie Karlsruhe.
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Surface effects of network materials based on strain gradient homogenized media
PublicationThe asymptotic homogenization of periodic network materials modeled as beam networks is pursued in this contribution, accounting for surface effects arising from the presence of a thin coating on the surface of the structural beam elements of the network. Cauchy and second gradient effective continua are considered and enhanced by the consideration of surface effects. The asymptotic homogenization technique is here extended to...
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Hardened Steel Surface Waviness Created by Rolling Burnishing Process
PublicationThe surface of the finishing machined parts is defined mainly by roughness parameters. Growing demands on the part, especially mating sliding or rolling, require the specification of additional parameters, such as waviness parameters, particularly when there is significant resistance to seizing or noise reduction. This paper presents surface waviness characteristics of hardened burnished steel.
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Selected aspects of the surface quality of the wooden elements after planing
PublicationThe quality of the surface of wooden elements, that have been planed, has got a crucial meaning in the whole production process flow, since the obtained effects affect the quality of wooden surface after painting. The emergence of defects in most cases causes need to qualify workpiece as a scrap part or additional work activity must be done. In the paper selected results of the investigation of the effect of the cutting tool wear...
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Tyre/road noise reduction of poroelastic road surface tested in a laboratory
PublicationA so-called poroelastic road surface (PERS) is being developed in Europe. This contains a large percentage of rubber particles mixed with hard aggregate (stone and sand) and bound with polyurethane. This gives high air void content (around 30 %), high elasticity and smooth texture, all of which should give low noise properties. Inthis experiment anominally 30 mm thick sample of PERS was mounted on a steel drum. Various car tyres...
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Surface sliding in human abdominal wall numerical models: Comparison of single-surface and multi-surface composites
PublicationDetermining mechanical properties of abdominal soft tissues requires a coupled experimental-numerical study, but first an appropriate numerical model needs to be built. Precise modeling of human abdominal wall mechanics is difficult because of its complicated multi-layer composition and large variation between specimens. There are several approaches concerning simplification of numerical models, but it is unclear how far one could...
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Microstructure and residual stresses in surface coatings with PTFE reservoirs
PublicationThe paper presents the results of experimental study into the microstructure and changes in residual stresses resulting from sliding and rolling/sliding loaded interaction between metallic surface coatings with embedded PTFE reservoirs and various counter faces. It was found that before testing surface coatings had compressive residual stresses. Molybdenum coating with all types of PTFE reservoirs displayed, as a result of testing,...
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The effect of thermal modification on the quality of the milled surface of beech and pine wood
PublicationThe article deals with the effect of thermal modification on the quality of the created surface during milling on CNC milling cutters. The quality of the created surface is evaluated based on surface roughness, specifically its roughness parameter Ra. The observed surface is created by a shank cutter with a diameter of 20 mm and three cutting edges in a spiral at a standard speed of 18,000. min-1. The article compares thermally...
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Reduction in Errors in Roughness Evaluation with an Accurate Definition of the S-L Surface
PublicationCharacterization of surface topography, roughly divided into measurement and data analysis, can be valuable in the process of validation of the tribological performance of machined parts. Surface topography, especially the roughness, can respond straightly to the machining process and, in some cases, is defined as a fingerprint of the manufacturing. When considering the high precision of surface topography studies, the definition...
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Distribution and bioavailability of mercury in the surface sediments of the Baltic Sea
PublicationThe study aimed to determine the level of mercury (Hg) and its labile and stable forms in the surface sediments of the Baltic Sea. The work considers the impact of current and historical sources of Hg on sediment pollution, together with the influence of different environmental parameters, including water inflows from the North Sea. Surface sediments (top 5 cm) were collected in 2016–2017 at 91 stations located in different...
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Marine autonomous surface ship - control system configuration
PublicationThis paper addresses the problem of marine autonomous surface ship (MASS) control. The contribution of the paper is the development of a control system configuration, done assuming fully autonomous MASS operation under distinct operational conditions. The overview of hardware and software selection is included.
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Occurrence of Surface Active Agents in the Environment
PublicationDue to the specific structure of surfactants molecules they are applied in different areas of human activity (industry, household). After using and discharging from wastewater treatment plants as effluent stream, surface active agents (SAAs) are emitted to various elements of the environment (atmosphere, waters, and solid phases), where they can undergo numerous physic-chemical processes (e.g., sorption, degradation) and freely...
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Surface and Trapping Energies as Predictors for the Photocatalytic Degradation of Aromatic Organic Pollutants
PublicationIn this study, anatase samples enclosed by the majority of three different crystal facets {0 0 1}, {1 0 0}, and {1 0 1} were successfully synthesized. These materials were further studied toward photocatalytic degradation of phenol and toluene as model organic pollutants in water and gas phases. The obtained results were analyzed concerning their surface structure, reaction type, and surface development. Moreover, the regression...
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The Impact of Drying Conditions on the Surface Color Changes of Pine Wood
PublicationThe article presents the impact of drying process and selected parameters on the color changes on the surface of pine wood (Pinus sylvestris L.). Three predetermined process conditions (modes), mild, normal, and intensive, were investigated. The experiments were conducted using a semi-industrial scale dryer designed at the Gdańsk University of Technology with a loading capacity of 0.55 m3. The drying process was applied to pine...
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Development and Validation of SPE-HPLC-MS/MS Method for Determining Cyclophosphamide in Surface Waters
PublicationA rapid and selective method for trace amounts determination of cyclophosphamide in surface water samples has been developed. A solid phase extraction SPE method for extraction and clean-up procedure has been optimized for determination by reversed-phase high-performance liquid chromatography with tandem mass spectrometry. The analyses proceed in the positive ion mode by means of the electrospray ionization method (ESI). Clean...
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A tight-binding model of a carbon nanotube interacting with TiO2 rutile (110) surface
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Surface area investigation of materials with transition layers of continuously changing electron density
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Surface quality and topographic inspection of variable compliance part after precise turning
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Nexus between stock markets, economic strength, R&D and environmental deterioration: new evidence from EU-27 using PNARDL approach
PublicationThis research investigates the impact of stock market indices, economic strength, and research and development expenditures on environmental deterioration in the EU-27 countries for the period 2000–2020. This study utilized linear and non-linear panel ARDL to estimate the short- and long-run effect. According to the results, the stock market indices have negative effect on environmental deterioration in the symmetric form. However,...
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Experimental bases for the rail track surface damage detection system
PublicationA diagnosis of rail surface is generally based on the classical method of direct assessment and track geometry measurements. Identification and qualification of inequality and damage on the surface rails is depend on the skills and experience person who conducting inspection. In times of increasing exploitation of railways, infrastructure managers decide to use systems supporting the assessment of technical condition of the railways....
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Surface Texture Analysis of Hardened Shafts after Ceramic Ball Burnishing
PublicationThis article represents the results of testing the surface condition of shafts manufactured by the burnishing process. The shafts with a hardness of approximately 62 HRC (Rockwell C). were burnished with a ceramic ball (Si3N4), where the force range was controlled by the means of a hydraulic system. The machining process consisted of hard turning shafts with cubic boron nitride (CBN) inserts, followed by burnishing with the use...
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Road surface roughness estimation employing integrated position and acceleration sensor
PublicationAssessment of a surface quality being an essential task for the authorities supervising the roads provides the subject of the paper. Information about riding quality of a pavement, important for drivers, both in terms of their comfort and safety is collected during experiments employing mobile sensors. The paper describes the use of a miniature position and acceleration sensor for evaluation of the roughness of the road surface....
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Anti-plane waves in an elastic thin strip with surface energy
PublicationWe consider anti-plane motions of an elastic plate taking into account surface energy within the linear Gurtin–Murdoch surface elasticity. Two boundary-value problems are considered that describe complete shear dynamics of a plate with free faces or with free and clamped faces, respectively. These problems correspond to anti-plane dynamics of an elastic film perfectly or non-perfectly attached to a rigid substrate. Detailed analysis...
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Influence of low-temperature physical hardening on stiffness and tensile strength of asphalt concrete and stone mastic asphalt
PublicationThis paper presents laboratory testing of stiffness modulus and indirect tensile strength of three asphalt concrete (AC) and three stone mastic asphalt (SMA) mixes after isothermal storage at temperature of -20oC, at different time intervals up to 16 days. The tests under repeated dynamic loading showed physical hardening of all tested mixes which was manifested by an evident increase of their stiffness moduli after isothermal...
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Surface quality control of a thin SiN layer by optical measurements
PublicationFiber optic interferometers have a wide range of applications, including biological and chemical measurements. Nevertheless, in the case of a reflective interferometer setup, standard silver mirrors cannot be used in every measurement, due to their chemical activity. This work investigates the surface quality of a thin optical layer of silicon nitride (SiN), which can serve as an alternative material for silver mirrors. We present...
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Diamond surface modification following thermal etching of Si supported hydrogenated diamond films by DBr
PublicationZbadano, wykorzystując spektroskopię oscylacyjną (HREELS - High Resolution Electron Energy Loss Spectroscopy) modyfikacje chemiczne powierzchni wodorowanego diamentu, umieszczonego na podkładzie krzemowym i wystawionego na działanie DBr a następnie podgrzanego do temp. powyżej 600 st.K. Przedstawiona procedura powoduje tworzenie się węglika krzemu SiC na powierzchni warstwy diamentowej, co jest widoczne na widmie HREEL jako dwa...
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On Effective Bending Stiffness of a Laminate Nanoplate Considering Steigmann–Ogden Surface Elasticity
PublicationAs at the nanoscale the surface-to-volume ratio may be comparable with any characteristic length, while the material properties may essentially depend on surface/interface energy properties. In order to get effective material properties at the nanoscale, one can use various generalized models of continuum. In particular, within the framework of continuum mechanics, the surface elasticity is applied to the modelling of surface-related...
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Micro- and nano-Illite to improve strength of untreated-soil as a nano soil-improvement (NSI) technique
PublicationSoil stabilization is a technique of improving the geotechnical properties of soils for various engineering applications. However, conventional stabilizers such as cement and lime have some limitations, such as high cost, environmental impact, and durability issues. Therefore, there is a need for alternative and innovative stabilizers that can overcome these challenges. This study introduces nano-Illite, a type of clay mineral,...
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Mechanical Properties, Microstructure and Surface Quality of Polypropylene Green Composites as a Function of Sunflower Husk Waste Filler Particle Size and Content
PublicationAgricultural waste is a still untapped source of materials that can, in case of proper utilization, significantly improve the sustainability of polymers and their composites. In this work, polymer composites based on isotactic polypropylene were produced incorporating ground sunflower husk in the amount of 10 wt% and 20 wt%. The work’s main objective is to evaluate how preliminary fractioning of this agricultural waste filler affects...
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Treated wasetewater as a source of humic substances in surface waters
PublicationHumic substances impose substantial effect on the aquatic environment as well as the water organisms and human health. Among other features, the humic acids determine organoleptic properties of surface waters. Therefore explanation of the origin and properties of humic acids in surface waters is one of the priorities of water technology.Recently it was pointed out that in the wastewater treatment process organic compounds characterized...
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Effects of Surface Energy and Surface Residual Stresses on Vibro-Thermal Analysis of Chiral, Zigzag, and Armchair Types of SWCNTs Using Refined Beam Theory
PublicationIn this article, vibration characteristics of three different types of Single-Walled Carbon Nanotubes (SWCNTs) such as armchair, chiral, and zigzag carbon nanotubes have been investigated considering the effects of surface energy and surface residual stresses. The nanotubes are embedded in the elastic substrate of the Winkler type and are also exposed to low and high-temperature environments. A new refined beam theory namely, one-variable...
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FURTHER REMARKS ON THE SURFACE VIS IMPRESSA CAUSED BY A FLUID-SOLID CONTACT
PublicationIt is well-known that, nano-mechanics should take into account not only physical phenomena occuring within the bulk but, first of all, the physical phenomena appropriate for a surface of two materials contact. The huge volume density of internal surfaces as well countours lines located within the nanomaterial results in our interest in, apart from classical form of mass, momentum and entropy transport, those modes of transportation...
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TIRE/ROAD NOISE AND TIRE ROLLING RESISTANCE ON PROTOTYPE PERS SURFACE
PublicationPoroelastic road surfaces are characterized by low noise of tires running on them.Road pavements of this type are promising solution to problems related to traffic noise in cities and on rural roads. Some technical problems still have to be solved, in particular regarding durability and skid resistance on wet surface. Ongoing and planned works are to contribute to create a quiet, durable and safe road surface, which will become...
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On weak solutions of boundary value problems within the surface elasticity of Nth order
PublicationA study of existence and uniqueness of weak solutions to boundary value problems describing an elastic body with weakly nonlocal surface elasticity is presented. The chosen model incorporates the surface strain energy as a quadratic function of the surface strain tensor and the surface deformation gradients up to Nth order. The virtual work principle, extended for higher‐order strain gradient media, serves as a basis for defining...