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Wyniki wyszukiwania dla: CYCLIC MECHANICAL STRESS
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Corrosion fatigue crack propagation rate characteristics for weldable ship and offshore steels with regard to the influence of loading frequency and seawater temperature
PublikacjaAfter Vosikovsky (1975), the corrosion fatigue crack growth rate (CFCGR) characteristics have been divided into three regions. The region-III rates are very close to mechanical fatigue crack growth rates. CFCGR formulae, including the long-crack length effect (in region I only), the loading frequency effect (in region II only), and the saltwater temperature effect, have been proposed. It has been assumed that CFCGR is proportional...
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Chromium-Catalyzed CO2–Epoxide Copolymerization
PublikacjaIminopyrrole, aminopyrrole, and aminophosphine ligands were complexed with various chromium sources, producing eight complexes that were tested for their catalytic behavior toward epoxide–CO2 copolymerization. As elucidated by MALDI-TOF-MS, copolymerizations afforded polycarbonates and poly(ether-carbonates) exhibiting linear or cyclic topologies.
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Rheology of potato starch chemically modified with microwave-assisted reactions
PublikacjaNative potato starch was sulfated, selenated, borated, silicated and zincatated by means of microwave-assisted reactions with varying doses of relevant reagents. Resulting products were characterized involving rheological behavior of pastes, their weight-average molecular weight (Mw), and radius of gyration (Rg). Most of the pastes showed shear-thinning behavior, with the flow behavior index (n) below unity. The pastes of starch...
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Psychosocial risks associated with the profession of train driver
PublikacjaExcellent competencies as well as a good physical and mental health are required in train drivers’ profession. Despite the changes in the structure of employment the train drivers above 46 years and job tenure longer than 30 years are the largest group. The generation gap is becoming more pronounced, and its fulfilment will not be easy. It is related not only to training of new personnel but also promotion of healthy work environment...
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Drilling couples and refined constitutive equations in the resultant geometrically non-linear theory of elastic shells
PublikacjaIt is well known that distribution of displacements through the shell thickness is non-linear, in general. We introduce a modified polar decomposition of shell deformation gradient and a vector of deviation from the linear displacement distribution. When strains are assumed to be small, this allows one to propose an explicit definition of the drilling couples which is proportional to tangential components of the deviation vector....
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Local buckling of compressed flange of cold-formed channel members made of aluminum alloy
PublikacjaThe paper deals with local buckling of a compressed single flange of thin-walled channel cold- formed columns and beams made of aluminum alloy. Material is described by means of the Ramberg-Osgood constitutive equation. Axial compression of the columns and beams undergoing bending is taken into consid- eration. A simple model of the member flange in the form a long beam elastically connected to the web is used to find the critical...
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Właściwości mechaniczne tworzywa PET - przegląd literatury
PublikacjaThe article describes the influance of the microstructure and environment conditions on the mechanical properties of PET material. From the microskopic point of view, mechanical and thermal properties of PET material have the biggest influance on orientation and crystallization processes of material. From the macroskopic point of view mechanical properties can be described by parameters derived from strees-strain mechanical answers...
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Possible effects of the 1984 St. Clair River ice jam on bed changes
PublikacjaThis study examines the possible effect of the record ice jam of 1984 in the St. Clair River on river bed changes and conveyance. Numerical simulations were made to examine the flow and bed shear stresses during the jam formation and release periods. Simulation results indicate that the ice jam in the river did not cause a significant increase in bed shear stress compared to pre- and post-jam open water conditions. The insignificant...
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EXPERIMENTAL STUDY OF SURFACE ROUGHNESS EFFECT ONTHE RHEOLOGICAL BEHAVIOR OF MR FLUID
PublikacjaPaper presents the results of shear stress measurements of a commercial magnetorheological fluid using a plate-plate type geometry with a modified working surface. The purpose of the study was to determine the effect of changing the roughness of the measuring plate on the obtained shear stress results. Controlled shear rate tests and Magneto Sweep measurements were carried out for three MR fluid layer heights. The tests were...
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Protective properties of Al2O3 + TiO2 coating produced by the electrostatic spray deposition method
PublikacjaMechanical resistance of Al2O3 + TiO2 nanocomposite ceramic coating deposited by electrostatic spray deposition method onto X10CrAlSi18 steel to thermal and slurry tests was investigated. The coating was produced from colloidal suspension of TiO2 nanoparticles dispersed in 3 wt% solution of Al2(NO3)3, as Al2O3 precursor, in ethanol. TiO2 nanoparticles of two sizes, 15 nm and 32 nm, were used in the experiments. After deposition,...
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Estimation of Failure Initiation in Laminated Composites by means of Nonlinear Six-Field Shell Theory and FEM
PublikacjaThe monography deals with the problem of failure initiation in thin laminated composites. Known techniques of laminate structures modelling are briefly characterised. Eventually, shell based approach is chosen for the purpose of the description of the composite structures behaviour, as it predicts their deformation and states of stress effectively in a global sense. The nonlinear six parameter shell theory (6p theory) with asymmetric...
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FEM analysis of composite materials failure in nonlinear six field shell theory
PublikacjaThe monography deals with the problem of failure initiation in thin laminated composites. Known techniques of laminate structures modelling are briefly characterised. Eventually, shell based approach is chosen for the purpose of the description of the composite structures behaviour, as it predicts their deformation and states of stress effectively in a global sense. The nonlinear six parameter shell theory (6p theory) with asymmetric...
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The experimental and numerical investigation of fracture behaviour in PMMA notched specimens under biaxial loading conditions – Tension with torsion
PublikacjaThis paper presents the results of experimental fracture test of flat PMMA specimens under biaxial loading condition tension with torsion (proportional). The specimens were made in two thicknesses: 5 and 15 mm and were weakened with V-type edge notches with different root radii: 0.5; 2 and 10 mm. Thanks to the ARAMIS 3D 4 M non-contact vision system, measurement of the elongation and twist angle were recorded. During experimental...
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Nieliniowa statyka 6-parametrowych powłok sprężysto plastycznych. Efektywne obliczenia MES
PublikacjaGłównym zagadnieniem omawianym w monografii jest sformułowanie sprężysto-plastycznego prawa konstytutywnego w nieliniowej 6-parametrowej teorii powłok. Wyróżnikiem tej teorii jest występujący w niej w naturalny sposób tzw. stopień 6 swobody, czyli owinięcie (drilling rotation). Podstawowe założenie pracy to przyjęcie płaskiego stanu naprężenia uogólnionego na ośrodek typu Cosseratów. Takie podejście stanowi oryginalny aspekt opracowania....
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Metallurgical characterization and high-temperature tensile failure of Inconel 617 alloy welded by GTAW and SMAW—a comparative study
PublikacjaTwo types of the weld joint of Inconel 617 alloy were produced using gas tungsten arc welding (GTAW) and shielded metal arc welding (SMAW) processes with ERNiCrCoMo-1 filler metal and ENiCrCoMo-1 electrode, respectively. The weld metal showed the segregation of the principle alloying elements like Mo and Cr along the inter-dendritic spaces, triggering the formation of secondary phases. The microstructure characterization of the...
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Quality increase for single-welded joints of thin-walled structures by means of simulation modelling
PublikacjaThe Simulation calculation module and the SolidWorks software package have helped to define the optimal shape and dimensions of single-welded joints which may serve the basis for calculating the process parameters of welding. Having compared the models with different weld cross-sections the authors have defined that the weld height and width do not significantly affect the stress concentration, and the stress concentration and...
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Support for Employees with ASD in the Workplace Using a Bluetooth Skin Resistance Sensor–A Preliminary Study
PublikacjaThe application of a Bluetooth skin resistance sensor in assisting people with Autism Spectrum Disorders (ASD), in their day-to-day work, is presented in this paper. The design and construction of the device are discussed. The authors have considered the best placement of the sensor, on the body, to gain the most accurate readings of user stress levels, under various conditions. Trial tests were performed on a group of sixteen...
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A universal method for the identification of genes encoding amatoxins and phallotoxins in poisonous mushrooms
PublikacjaABSTRACT Background. As the currently known diagnostic DNA targets amplified in the PCR assays for detection of poisonous mushrooms have their counterparts in edible species, there is a need to design PCR primers specific to the genes encoding amanitins and phallotoxins, which occur only in poisonous mushrooms. Objective. The aim of the study was testing of PCR-based method for detection of all genes encoding hepatotoxic cyclic...
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Some problems of slide bearing material fatigue evaluation.
PublikacjaA slide bearing alloy resistance against fatigue failures have been investigated for three different lubricants, different heat loadings and different stress ratio κ values. The research methods and data handling procedures for determination of particular parameter effects on fatigue strength have been described and analysed for experiments that were set and performed in laboratory tester SKMR-2. Main and interaction effects of...
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Geometrically nonlinear FEM analysis of 6-parameter resultant shell theory based on 2-D Cosserat constitutive model
PublikacjaWe develop the elastic constitutive law for the resultant statically and kinematically exact, nonlinear, 6-parameter shell theory. The Cosserat plane stress equations are integrated through-the- thickness under assumption of the Reissner-Mindlin kinematics. The resulting constitutive equations for stress resultant and couple resultants are expressed in terms of two micropolar constants: the micropolar modulus Gc and the micropolar...
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Effect of Tool Positioning Factors on the Strength of Dissimilar Friction Stir Welded Joints of AA7075-T6 and AA6061-T6
PublikacjaFriction Stir Welding (FSW) is a solid-state bonding technique. There are many direct and indirect factors affecting the mechanical and microstructural properties of the FSW joints. Tool offset, tilt angle, and plunge depth are determinative tool positioning in the FSW process. Investigating the effect of these factors simultaneously with other parameters such as process speeds (rotational speed and translational speed) and tool...
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Nonlinear dynamic analysis of the pure “buckling” mechanism during blow-out trauma of the human orbit
PublikacjaConsidering the interplay between orbital bones and intraorbital soft tissues, commonly accepted patterns of the blow-out type of trauma within the human orbit require more thorough investigation to assess the minimal health-threatening impact value. Two different three-dimensional finite element method (FEM) models of the human orbital region were developed to simulate the pure “buckling” mechanism of orbital wall fracture in...
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Influence of soil anisotropic stiffness on the deformation induced by an open pit excavation.
PublikacjaIn this paper, the problem of deformation induced by an open pit excavation in anisotropic stiff soils is analysed by FE modelling. The presented research is focused on the influence of material model with anisotropic stiffness on the accuracy of deformation predictions as compared with the field measurements. A new hyperelastic-plastic model is applied to simulate anisotropic mechanical behaviour of stiff soils. It is capable...
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Influence of Giant Reed (Arundo Donax L.) Culms Processing Procedure on Physicochemical, Rheological, and Thermomechanical Properties of Polyethylene Composites
PublikacjaGiant reed (Arundo donax L.) is a plant species with a high growth rate and low requirements, which makes it particularly interesting for the production of different bioproducts, including natural fibers. This work assesses the use of fibers obtained from reed culms as reinforcement for a high-density polyethylene (HDPE) matrix. Two different lignocellulosic materials were used: i) shredded culms and ii) fibers obtained by culms...
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Thermal Decomposition of Carbamoyl Meldrum’s Acids: A Starting Point for the Preparation of 1,3-Oxazine Derivatives
PublikacjaThe ability to undergo [4 + 2] versus [2 + 2] cycloaddition was under investigation for ketenes thermally generated from carbamoyl Meldrum’s acid. Usually, 1,3-oxazino-5-carbamoylo-4,6-diones are formed when carbamoyl Meldrum’s acid reacts with imine. However, in some cases, a reaction takes an unexpected course, leading to the formation of tetraponerines alkaloids derivatives or cyclic iminoethers.
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Multiaxial Fatigue Behaviour of SLM 18Ni300 Steel
PublikacjaFatigue behaviour of SLM 18Ni300 steel under proportional bending-torsion loading is studied. The fatigue tests are conducted under pulsating loading conditions using tubular specimens with a transversal circular hole. Three ratios of the normal stress to shear stress are considered, namely σ/τ=4,σ/τ=2 and σ/τ = 4/3. Crack initiation sites were found for two diametrically opposite points around the hole, whose locations are governed...
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Triazoloacridone C-1305 impairs XBP1 splicing by acting as a potential IRE1α endoribonuclease inhibitor
PublikacjaInositol requiring enzyme 1 alpha (IRE1α) is one of three signaling sensors in the unfolding protein response (UPR) that alleviates endoplasmic reticulum (ER) stress in cells and functions to promote cell survival. During conditions of irrevocable stress, proapoptotic gene expression is induced to promote cell death. One of the three signaling stressors, IRE1α is an serine/threonine-protein kinase/endoribonuclease (RNase) that...
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ESTIMATION OF YOUNG`S MODULUS OF THE POROUS TITANIUM ALLOY WITH THE USE OF FEM PACKAGE
PublikacjaPorous structures made of metal or biopolymers with a structure similar in shape and mechanical properties to human bone can easily be produced by stereolithographic techniques, e.g. selective laser melting (SLM). Numerical methods, like Finite Element Method (FEM) have great potential in testing new scaffold designs, according to their mechanical properties before manufacturing, i.e. strength or stiffness. An example of such designs...
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Wybrane problemy plastyczności w płaskim ośrodku mikropolarnym
PublikacjaW pracy analizuje się sprężysto-plastyczny płaski ośrodek mikropolarny. Do rozwiązań równań plastyczności wykorzystuje się technikę Closest Point Projection Method. Przedstawiono przykład numeryczny w płaskim stanie naprężenia, zasygnalizowano problem lokalizacji w zadaniach z osłabieniem materiału.
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Enhanced Charge Storage Mechanism And Long-Term Cycling Stability In Diamondized Titania Nanocomposite Supercapacitors Operating In Aqueous Electrolytes
PublikacjaThe long cycle life stability jointly with high energy density are limiting broader feasible applications of supercapacitors. The novel diamondized titania nanocomposite supercapacitors deliver high power and energy densities along with high capacitance retention rates. Supercapacitor electrodes were fabricated utilizing a combination of Ti anodization followed by chemical vapor deposition resulting in simultaneous growth of complex...
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Changes in psychological distress among Polish medical university teachers during the COVID-19 pandemic
PublikacjaOur study aims to update knowledge about psychological distress and its changes in the Polish group of academic medical teachers after two years of a global pandemic. During the coronavirus disease, teachers were challenged to rapidly transition into remote teaching and adapt new assessment and evaluation systems for students, which might have been...
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Vibroflotation Control of Sandy Soils using DMT and CPTU
PublikacjaVibroflotation is a typical improvement method for the cohesionless deposits of high thickness. The compaction method was applied to densify sandy deposits in Gdynia Port. Compaction control was verified with CPTU and DMT tests. Some examples of interpretation of soundings in pre-treated and compacted sands are shown. The classification diagrams are given for pre-treated and compacted sand. The stress history of the deposits is...
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Distinctive properties of Scots pine (Pinus sylvestris L.) originating from the Carpathian and Great Poland-Pomeranian of Nature and Forest Land
PublikacjaIn this paper values of properties of Scots pine, the fracture toughness and of shear yield stress in the shear zone are presented. Samples of Scotch pine (Pinus sylvestris L.) wood of two provenances from Poland were tested. These properties were determined from the values of cutting power obtained experimentally on the saw frame PRW-15M. The values of fracture toughness and shear yield stress based on the Atkins model for cutting...
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The influence of combination of binding agents on fatigue properties of deep cold in-place recycled mixtures in Indirect Tensile Fatigue Test (ITFT)
PublikacjaThe publication presents fatigue properties of cold recycled mixtures for eight combinations of binding agents (cement and bituminous emulsion). Cold recycled mixtures were evaluated in Indirect Tensile Fatigue Test (ITFT) at the temperature of 20 C in controlled stress mode. As a function of horizontal stress, fatigue life is strongly influenced by combination of the binding agents. When fatigue life is analyzed as a function...
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Shape and force control of cable structures with minimal actuators and actuation
PublikacjaShape adjustment and stress control can be considered as one of the effective parameters in prestressed cable structures since such structures are widely constructed nowadays due to their characteristics. The assembly errors and applied loads hugely affect the cables’ nodal positions and stress due to their delicacy. The former could disturb the shape, which affects the appearance and the function of the structure. In contrast,...
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NON-LINE ANALYSIS OF STIFFNESS IN COMPRESSION CONDITIONS
PublikacjaThe analyzes were aimed at demonstrating the influence of parameters describing the deformation of the structure on the uncertainty of critical force, and the impact of technological imperfections on stress uncertainty in compression conditions. In a linear buckling analysis, the problem is considered only for the initial, permanent state of the stiffness matrix. In the case of demonstrating the influence of initial deformations...
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Book Chapter in the Prime Archives in Chemistry: 2nd Edition (dissemination of knowledge)
PublikacjaTo cite a chapter in a book include: Jaroslaw Spychala. The CON−H….+NH2 Blue-Shifting H-Bond Stabilizing Effect on Z Secondary Amides and Cyclic System Conformational Rearrangement through an Alkylamine-Chain Migration Pathway. In: VSR Rajasekhar Pullabhotla, editor. Prime Archives in Chemistry: 2nd Edition. Hyderabad, India: Vide Leaf. 2022. https://doi.org/10.1155/2022/1707245
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Non linear identification of underwater vehicles. W: [CD-ROM] Conference Proceedings. The 29th Israel Conference on Mechanical Engineering. May 12-13, 2003 Haifa, Israel. Haifa: Technion - Israel Inst. Technol.**2003[B8] s. 1-8, 5 rys. bibliogr. 7 poz. Nieliniowa identyfikacja pojazdów podwodnych.
PublikacjaArtykuł dotyczy identyfikacji nieliniowych modeli pojazdów podwodnych o wie-lu zmiennych. Zaproponowana metoda działa w obszarze czasu rzeczywistego imoże być stosowana do nieliniowych modeli, które są liniowe w części doty-czącej nieznanego wektora parametrów. W celu poradzenia sobie z parametramizmieniającymi się w czasie, zastosowano rekursyjną wersję algorytmu identy-fikacji. Po krótkim opisie matematycznych podstaw...
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A Flexible Nafion Coated Enzyme‐free Glucose Sensor Based on Au‐dimpled Ti Structures
PublikacjaThe detection of glucose at low concentrations using electrochemical sensors is of great importance due to the possibility of using different human body fluids than blood, such as e.g. urine, saliva, sweat or tears. The interest behind those biofluids is related to their utility in non-invasive sugar determination. In this work, we present flexible, fully biocompatible electrode material based on Au nanoparticles immobilized onto...
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INFLUENCE OF PRESERVATIVE ON THE TENSILE STRENGTH OF THE TISSUE OF PORCINE CIRCULATORY SYSTEM
PublikacjaCurrently one of the leading causes of death worldwide is heart diseases which include calcification of heart valves and vascular aneurysm. There are many biomaterials that can substitute pathologically altered tissue, however, none of them is as perfect as native tissue. Currently, scientists are looking for new biomaterials that can be successfully implanted without exposing the patient to reoperation. Each material introduced...
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THERMOMECHANICAL PERFORMANCE OF FLEXIBLE POLYURETHANE FOAMS AS A FUNCTION OF THE ISOCYANATE INDEX
PublikacjaPolyurethane foams are very versatile materials applied in different branches of industry. Their popularity is attributed, among others, to the flexibility in engineering their mechanical performance by the adjustment of their formulations. One of the most crucial factors is the isocyanate index, determining the ratio between the free hydroxyl and isocyanate groups present in the polyurethane system. By the change of this ratio,...
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Underwater Local Cavity Welding of S460N Steel
PublikacjaIn this paper, a comparison of the mechanical properties of high-strength low-alloy S460Nsteel welded joints is presented. The welded joints were made by the gas metal arc welding (GMAW)process in the air environment and water, by the local cavity welding method. Welded joints were testedfollowing the EN ISO 15614-1:2017 standard. After welding, the non-destructive—visual, penetrant,radiographic, and ultrasonic (phased array) tests...
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Comparison of calculated and measured thermal stresses in asphalt concrete
PublikacjaThe paper presents the comparison of calculated and measured thermal stresses induced in restrained asphalt concrete specimens by cooling. Thermal stresses were measured in the Thermal Stress Restrained Specimen Test. The calculations of thermal stresses were performed with the use of a theoretical formula based on the temperature dependent stiffness modulus. The novel approach applied in this paper was that the stiffness modulus...
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SIGNIFICANT GUIDELINE FOR THE DAMAGE INDICES APPLIED TO REINFORCED CONCRETE STRUCTURES
PublikacjaIn this paper, based on a deep overview and literature study, the different formulas proposed for damage indices (DIs) applied to reinforced concrete structures under monotonic or cyclic loading are classified and presented. The DIs are applied to quantify the damages to structures, ranging from zero to one. Normally, they are applied to make a decision for repairing or demolition of the structures in the post-earthquake phases. Keywords:...
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Synthesis of Novel Polycationic Quaternary Di- and Trispirocyclic Benzenes
PublikacjaTreatment of hexakis(bromomethyl)benzene with a cyclic amine {morpholine, 1-methylpiperazine, 1-(2-hydroxyethyl)piperazine, isonipecotamide, 4-hydroxypiperidine, 4-[3-(4-piperidyl)propyl]-1-piperidineethanol} gave a range of di- and trispirocyclic ammonium salts in satisfactory yields (22-62%). Presumably, the electrostatic and repulsion forces play an important role in their formation. The structure in soln. and the protonation...
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The effect of high molecular weight bio-based diamine derivative of dimerized fatty acids obtained from vegetable oils on the structure, morphology and selected properties of poly(ether-urethane-urea)s
PublikacjaIn this work, the effect of the high molecular weight bio-based diamine on the chemical structure and selected properties of poly(ether-urethane-urea)s has been investigated. The ether-urethane prepolymer was cured using 1,4-butanediol and/or bio-based diamine. Mentioned chain extenders were used separately or in the mixture, and their different molecular weight and chemical structure resulted in obtaining materials with diversified...
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Tensile strength of a weave tendon suture using tendons of different sizes
PublikacjaThis study compared the maximum load, stress, elongation at failure and the mode of failure of three kinds of tendons most frequently used for tendon grafting and tendon transfers, using the Pulvertaftweave suture.
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Analiza wrażliwości tarczy z wykorzystaniem metody elementów skończonych
PublikacjaW pracy przedstawiono przykład zastosowania analizy wrażliwości tarczy modelowanej przy pomocy metody elementów skończonych. Podstawy teoretyczne oraz przykład numeryczny dotyczą wpływu różnicowania grubości całej tarczy oraz jej obszarów – jako zmiennej pro-jektowej – na przemieszczenie wybranego punktu – jako zmiennej stanu.
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Analiza możliwości wykorzystania trójosiowego stanu naprężenia w betonie ściskanych słupów żelbetowych.
PublikacjaW artykule przeprowadzono analizę możliwości wykorzystania trójosiowego stanu naprężeń ściskających w słupach uzwojonych i słupach CFST. Przeprowadzono także analizę możliwości zwiększenia efektywności uzwojenia i stalowego płaszcza przez zastosowanie betonu ekspansywnego. Przeprowadzone analizy opracowano na podstawie badań własnych autorów.
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Electro-thermal buckling of elastically supported double-layered piezoelectric nanoplates affected by an external electric voltage
PublikacjaPurpose Thermal buckling of double-layered piezoelectric nanoplates has been analyzed by applying an external electric voltage on the nanoplates. The paper aims to discuss this issue. Design/methodology/approach Double-layered nanoplates are connected to each other by considering linear van der Waals forces. Nanoplates are placed on a polymer matrix. A comprehensive thermal stress function is used for investigating thermal buckling....