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Search results for: ELASTO-AKUSTYKA
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The Role of Molecular Structure in Monte Carlo Simulations of the Secondary Electron Yield and Backscattering Coefficient from Methacrylic Acid
PublicationIn this paper, we show the influence of the chemical structure of four different conformers on the secondary electron emission and backscattering of an electron beam from a gel of methacrylic acid. The conformers have different permanent dipole moments, which determines the cross sections for elastic collisions with electrons. The cross sections are used in Monte Carlo simulations of an electron beam, which enters the gel of methacrylic...
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Synchronous black hole search in directed graphs
PublicationThe paper considers a team of robots which has to explore a graph G, where some nodes can be harmful. Robots are initially located at the so-called home base node. The dangerous nodes are the so-called black hole nodes, and once a robot enters in one of them, it is destroyed. The goal is to find a strategy in order to explore G in such a way that minimum number of robots is wasted. The exploration ends if there is at least one...
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Optimal and suboptimal algorithms for identification of time-varying systems with randomly drifting parameters
PublicationNoncausal estimation algorithms, which involve smoothing, can be used for off-line identification of nonstationary systems. Since smoothingis based on both past and future data, it offers increased accuracy compared to causal (tracking) estimation schemes, incorporating past data only. It is shown that efficient smoothing variants of the popular exponentially weighted least squares and Kalman filter-based parameter trackers can...
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Geometrically nonlinear FEM analysis of 6-parameter resultant shell theory based on 2-D Cosserat constitutive model
PublicationWe 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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Diagnostics of historic columns using wave propagation
PublicationThis paper presents a numerical analysis of elastic wave propagation in columns of historical buildings for diagnostics purposes. Numerical calculations were performed using the finite element method in the Abaqus software package. The analysis was carried out for three types of brick columns: a full column, a column filled with debris, and a column empty inside. The excitation was in the form of a wave packet and signals of propagating...
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Laminated plates and shells - first ply failure analysis within 6-parameter shell theory
PublicationThis work describes Tsai-Wu and Hashin criteria modifications, dictated by nonlinear 6-parameter shell theory with asymmetric strain measures and drilling rotation. The material law is based on standard orthotropic elastic constants for a non-polar continuum, under plane state of stress. First ply failure loads of cylindrical panel subjected to pressure and flat compressed plate are estimated by means of Finite Element Analysis....
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Numerical FDM modelling of wave propagation in concrete structure
PublicationThe article presents application of finite difference method to damage detection and its size evaluation in concrete structure by elastic wave propagation method. The simulations of wave propagation in concrete structure were performed for six different damage scenarios. Damages were modelled as areas with changed material properties. Investigation focused on the influence of damage size on the energy of wave reflection. Presented...
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Linia metra nr 4 w São Paulo
PublicationSão Paulo o powierzchni niewiele większej od województwa opolskiego zamieszkuje 10-krotnie więcej ludności. To największe miasto Brazylii leży na wysokości 700-900 m n.p.m., a lokalne różnice wysokości są w wielu miejscach bardzo duże. Sprawny transport w tak wielkim, silnie zurbanizowanym i uprzemysłowionym organizmie miejskim ma wielkie zna-czenie. Lokalne władze, doceniając wagę problemu, dużą uwagępoświęcają rozwojowi komunikacji...
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Application of the distributed transfer function method and the rigid finite element method for modelling of 2-D and 3-D systems
PublicationIn the paper application of the Distributed Transfer Function Method and the Rigid Finite Element Method for modelling of 2-D and 3-D systems is presented. In this method an elastic body is divided into 1-D distributed parameter elements (strips or prisms). The whole body (divided into strips or prism) is described by a set of coupled partial differential equations. Solving this equations in the state space form it is possible...
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Similarity Measures for Face Images: An Experimental Study
PublicationThis work describes experiments aimed at finding a straightforward but effective way of comparing face images.We discuss properties of the basic concepts, such as the Euclidean, cosine and correlation metrics, test the simplest version of elastic templates, and compare these solutions with distances based on texture descriptors (Local Ternary Patterns). The influence of selected image processing methods (e.g. bilateral ltering)...
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Ruch migracyjny w średniowiecznym Gdańsku
PublicationW średniowiecznym Gdańsku, migracje ludności charekteryzowały się znaczną dynamiką. Do Gdańska przybywali głównie imigranci z Dolnych Niemiec, Lubeki, Holsztynu, Meklemburgii, Turyngii, Hestii, Śląska, Czech, Moraw, Skandynawii, Flandrii, Holandii, Anglii, Prus, a tkaże z Pomorza Gdańskiego, Żuław i Powiśla. Znaczną grupę stanowili przybysze z Niemiec, co wpłynęło na oblicze miasta. Gdańszczanie opuszczali swoje miasto w celach...
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Urban-rural Partnership
PublicationOmówiono koncepcję partnerstwa ''miasto-wieś'', opartą na idei zrównoważonego rozwoju regionalnego i policentrycznego modelu systemu miejskiego. Koncepcja ta, realizowana w krajach Unii Europejskiej, tworzy mechanizm redystrybucji zysków i korzyści uzyskiwanych w strefach dynamicznego rozwoju ośrodków miejskich na ich zaplecze wiejskie, ograniczania ujemnych skutków tej polaryzacji rozwoju i wzmacniania inicjatyw lokalnych na obszarach...
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Waveform design for fast clutter cancellation in noise radars
PublicationCanceling clutter is an important, but computation-ally intensive part of signal processing in noise radars. It is shown that considerable improvements can be made to a simple least squares canceler if minor constraints are imposed onto noise waveform. The proposed scheme is potentially capable of canceling clutter in real-time, even for high sampling rates.
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Cavity-expansion approximation for projectile impact and penetration into sand
PublicationA one-dimensional problem of a spherical cavity expanding at a constant velocity from zero initial radius in an infinite granular medium, which has the first-kind self-similar solution, is considered. We are solving this dynamic spherical cavity-expansion problem to model rigid spheres penetrating into a granular media. Elastic–plastic deformation of the granular media is described in a barotropic approximation, using the high-pressure...
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The influence of chemical composition of amide block on the thermal properties and structure of terpoly(ester-b-ether-b-amide) elastomers
PublicationMultiblock terpolymers-(PBT-b-PTMO-b-PA12,10)(n)- constituting the polymer systems, in which one of the three blocks (PBT) does not dissolve in PA12,10 block (hard phase) and, depending on its molecular weight is slightly soluble in PTMO block (soft phase), have been obtained. The DSC method was applied to investigate the thermal properties of these polymers and it was found that PBT block acts as an element that produces stiffness...
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On the well posedness of static boundary value problem within the linear dilatational strain gradient elasticity
PublicationIn this paper, it is proven an existence and uniqueness theorem for weak solutions of the equilibrium problem for linear isotropic dilatational strain gradient elasticity. Considered elastic bodies have as deformation energy the classical one due to Lamé but augmented with an additive term that depends on the norm of the gradient of dilatation: only one extra second gradient elastic coefficient is introduced. The studied class...
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Rekonstrukcja ewolucji układu przestrzennego średniowiecznego miasta i portu Szczecin Reconstruction of the Spatial Evolution of the Medieval City and Port of Szczecin
PublicationPraca rekonstruuje ewolucję układu osadniczego Szczecina w okresie od połowy VIII w. do początku XIV w., w oparciu o interpretację dostępnej literatury naukowej dotyczącej historii i archeologii Szczecina oraz metodę analizy planistycznej. Bardzo istotnym elementem opisu struktury urbanistycznej wczesnośredniowiecznego Szczecina było określenie roli i położenia portu. W wyniku analizy zmian układu przestrzennego miasta w omawianym...
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À la recherche de l’industrie perdue. La désindustrialisation en Italie entre débat public, réalité économique et fragilités structurelles du pays
PublicationThe paper outilines the main aspects of the public debate about Italian deindustrialization in the last 30 years
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Understanding the Relation between HR Practices and Pull Approach to Knowledge Sharing: Case Study
PublicationThe aim of this study is to identify the relationship between human resource (HR) practices, knowledge seeking and knowledge giving by applying the lenses of the motivation-opportunities-abilities framework in the context of the multinational enterprise subsidiary located in Central Europe. The article presents the research results using qualitative methodology, mainly based on semi-structured interviews among employees of a...
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Family business experience and the probability of starting a venture: gender differences in Poland
PublicationThe aim of this study is to analyse whether the experience of working in a family member’s business is related differently to the assessed probabilities of men and women starting their own new venture in the future. The research is conducted on a sample of 334 Polish undergraduate students. Poland is an efficiency-driven European economy with a substantial gender gap in entrepreneurship. The results obtained indicate that the relationship...
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On the synthesis of coupled-lossy resonator filters with unloaded quality factor control
PublicationA technique for fast synthesis of coupling matrix low-pass prototypes of generalized Chebyshev bandpass filters with lossy resonators is presented in this paper. The coupling matrix is found by solving a nonlinear least squares problem based on zeros and poles of filter's transfer functions. Additional constraints are introduced that allow one to control the level of unloaded quality factor of resonators.
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lLmondo globale
PublicationLo globalizzazione e i BRICS - Lo svilu the economic development of East Asia- The commodities market
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Investigation of abdomen surface deformation due to life excitation: implications for implant selection and orientation in laparoscopic ventral hernia repair
PublicationVentral hernia is a common medical problem. Statistically there are around 10% recurrences of the sickness. The authors' former investigation proved edges of the hernia orifice displacements to be one of the factors causing recurrence. Thus, experimental investigation of the abdomen surface deformation due to some normal activities of people is studied.The extreme strains, their localization and directions are identified. The acquired...
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Cross section calculations for electron scattering from platinum chemotherapeutic compounds
PublicationCross section for electron impact ionization of carboplatin, C6H12N2O4Pt, and oxaliplatin, C8H14N2O4Pt, have been calculated within binary-encounter-Bethe model for energies from the ionization threshold up to 5000 eV. Cross section for elastic electron scattering from carboplatin and oxaliplatin molecules have also been derived using independent atom method (IAM) and additivity rule for collision energies ranging from 50 eV to...
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Centra handlowo-usługowe - nowa funkcja dworców kolejowych
PublicationWobec rosnącego zapotrzebowania społecznego na dobra konsumpcyjne centra handlowe są atrakcyjnymi miejscami w miastach. Ich oddziaływanie na miasto jest widoczne i tyczy się nie tylko wpływu na drobny handel, ale również hierarchię miejskich ośrodków usługowych oraz komunikację. Jednym z atrakcyjnych przypadków lokalizacji funkcji handlowej jest dworzec kolejowy. Ważnym elementem kontroli rozwoju współczesnego handlu jest odpowiedzialne...
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On the use of uniaxial one-parameter damage laws for estimating fatigue life under multiaxial loading
PublicationThe goal of this paper is to evaluate the capabilities of different one-parameter fatigue laws to estimate crack initiation in notched components under multiaxial loading. Fatigue damage is accounted for through stress-based, strain-based, and energy-based approaches while the cyclic plasticity at the notch-controlled process zone is estimated using linear-elastic simulations. The results show that energy-based formulations established...
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Acceleration waves in the nonlinear micromorphic continuum
PublicationWithin the framework of the nonlinear elastic theory of micromorphic continua we derive the conditions for propagation of acceleration waves. An acceleration wave, also called a wave of weak discontinuity of order two, can be treated as a propagating nonmaterial surface across which the second derivatives of the placement vector and micro-distortion tensor may undergo jump discontinuities. Here we obtain the acoustic tensor for...
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Comparison of anti-plane surface waves in strain-gradient materials and materials with surface stresses
PublicationHere we discuss the similarities and differences in anti-plane surface wave propagation in an elastic half-space within the framework of the theories of Gurtin–Murdoch surface elasticity and Toupin–Mindlin strain-gradient elasticity. The qualitative behaviour of the dispersion curves and the decay of the obtained solutions are quite similar. On the other hand, we show that the solutions relating to the surface elasticity model...
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FEM ANALYSIS AND EXPERIMENTAL TESTS OF RIGID RISER HANGING SYSTEM
PublicationThe article presents the analysis, project, and experimental examination of an original rigid riser for Coil Tubing Pipes. The principle of riser operation is based on the use of friction forces. The research included the FEM analysis of the designed riser, calculations of the required bolt tensions, and checking the effect of the clamping force on stress distribution in the pipeline. The results of computer simulation were verified...
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Design of septic tanks placed on cohesive soils
PublicationThe paper presents a short review of literature with regard to design and erection of the reinforced concrete and concrete tanks. The authors investigated the underground septic tank with of 10 m3 capacity placed on cohesive soils. The authors compared the values of internal forces for soils in drained and undrained conditions with different geotechnical parameters: loamy sand of liquidity index IL = 0.1 and IL = 0.7 and clay with...
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On stress singularity near the tip of a crack with surface stresses
PublicationIn the framework of the simplified linear Gurtin–Murdoch surface elasticity we discuss a singularity of stresses and displacements in the vicinity of a mode III crack. We show that inhomogeneity in surface elastic properties may significantly affect the solution and to change the order of singularity. We also demonstrate that implicitly or explicitly assumed symmetry of the problem may also lead to changes in solutions. Considering...
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Detection of defects in PMMA beam using shear waves - numerical simulation and experiment
PublicationTest doświadczalny falami sprężystymi jest częścią systemu diagnostycznego belek. Autorzy badają pole przyspieszeń wywołane przepływem fal ultradźwiękowych i jego modyfikacje wynikające z wprowadzonych uszkodzeń belki. Artykuł porównuje wyniki eksperymentalne z symulacjami numerycznymi MES. The experimental test introduced in the paper is the part of the diagnostic system utilizing the elastic waves. The authors investigate the...
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The computational complexity of the backbone coloring problem for bounded-degree graphs with connected backbones
PublicationGiven a graph G, a spanning subgraph H of G and an integer λ>=2, a λ-backbone coloring of G with backbone H is a vertex coloring of G using colors 1, 2, ..., in which the color difference between vertices adjacent in H is greater than or equal to lambda. The backbone coloring problem is to find such a coloring with maximum color that does not exceed a given limit k. In this paper, we study the backbone coloring problem for bounded-degree...
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Detection and Mitigation of GPS Spoofing Based on Antenna Array Processing
PublicationIn this article authors present an application of spatial processing methods for GPS spoofing detection and mitigation. In the first part of this article, a spoofing detection method, based on phase delay measurements, is proposed. Accuracy and precision of phase delay estimation is assessed for various qualities of received signal. Spoofing detection thresholds are determined. Efficiency of this method is evaluated in terms of...
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Water-Lubricated Sintered Bronze Journal Bearings—Theoretical and Experimental Research
PublicationWater lubricated bearings are used from many years in shipbuilding, hydro power and other industries because of their advantages such as: extensive serviceable life, low coefficient of friction, longevity of shaft sleeve, good abrasion resistance, low maintenance required, unit simplicity, no danger of pollution and low price. Various types of water lubricated sliding bearings have been tested at the Technical University of Gdansk...
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Znaczenie procesu świadomego kształtowania systemów nadwodnych przestrzeni publicznych dla przekształceń struktury funkcjonalno-przestrzennej miast
PublicationPrzedmiotem rozprawy jest określenie znaczenia procesu świadomego kształtowania systemów nadwodnych przestrzeni publicznych w transformacji obszarów nadwodnych miast województwa pomorskiego oraz wpływu tych przestrzeni na przekształcanie się struktury funkcjonalno-przestrzennej miast. Z tego względu praca zawiera także próbę wyznaczenia specyficznych narzędzi, które mogą pomóc w tym procesie. Aby zrealizować wskazany cel przeprowadzono...
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Torsional elasticity and energetics of F1-ATPase
PublicationFoF1-ATPase is a rotary motor protein synthesizing ATP from ADP driven by a cross-membrane proton gradient. The proton flow through the membrane-embedded Fo generates the rotary torque that drives the rotation of the asymmetric shaft of F1. Mechanical energy of the rotating shaft is used by the F1 catalytic subunit to synthesize ATP. It was suggested that elastic power transmission with transient storage of energy in some compliant...
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Assessment of Thermal Stresses in Asphalt Mixtures at Low Temperatures Using the Tensile Creep Test and the Bending Beam Creep Test
PublicationThermal stresses are leading factors that influence low-temperature cracking behavior of asphalt pavements. During winter, when the temperature drops to significantly low values, tensile thermal stresses develop as a result of pavement contraction. Creep test methods can be suitable for the assessment of low-temperature properties of asphalt mixtures. To evaluate the influence of creep test methods on the obtained low-temperature...
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Positive solutions to Sturm–Liouville problems with non-local boundary conditions
PublicationIn this paper, the existence of at least three non-negative solutions to non-local boundary-value problems for second-order differential equations with deviating arguments α and ζ is investigated. Sufficient conditions, which guarantee the existence of positive solutions, are obtained using the Avery–Peterson theorem. We discuss our problem for both advanced and delayed arguments. An example is added to illustrate the results.
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Fast clutter cancellation for noise radars via waveform design
PublicationCanceling clutter is an important, but very expensive part of signal processing in noise radars. It is shown that considerable improvements can be made to a simple least squares canceler if minor constraints are imposed onto noise waveform. Using a combination of FPGA and CPU, the proposed scheme is capable of canceling both stationary clutter and moving targets in real-time, even for high sampling rates.
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Homoclinics for singular strong force Lagrangian systems
PublicationWe study the existence of homoclinic solutions for a class of generalized Lagrangian systems in the plane, with a C1-smooth potential with a single well of infinite depth at a point ξ and a unique strict global maximum 0 at the origin.Under a strong force condition around the singular point ξ, via minimization of an action integral, we will prove the existence of at least two geometrically distinct homoclinic solutions.
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Influence of nodes with positive eccentricity on load-carrying capasity of truss' top chords in trusses made of welded cold-formed members.
PublicationIn order to establish the influence of eccentric crossing of truss members on the load-carrying capacity of the folded chord of a hat-section truss, a research model was created and preliminary numerical analysis of the truss was performed with the use of Marc Mentat programme. Distorial instability of crossheads caused by deviation of loose (unmounted) channel section web’s bends was observed. Due to the slenderness of the section’s...
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Przyjazna miejskość kurortu innowacyjnego - studium przypadku
PublicationDefinicja przyjaznej przestrzeni publicznej we współczesnym środowisku miejskim mogłaby brzmieć: przestrzeń publiczna to szczególne, wyróżniające się fragmenty miasta, w których płynący czas aktualnych zdarzeń, przestrzeń przyrody, walory widokowe oraz istniejąca zabudowa i zagospodarowanie terenu budzą w odbiorcy pozytywne emocje, gdyż pozostają w wyczuwalnej dynamicznej równowadze. W kontekście tej definicji, należałoby zacząć...
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Vibration of the bridge under moving singular loads - theoretical formulation and numerical solution
PublicationThe paper presents the results of the numerical analysis of a simple vehicle passing over a simply supported bridge span. The bridge is modelled by a Euler-Bernoulli beam. The vehicle is modelled as a linear, visco-elastic oscillator, moving at a constant speed. The system is described by a set of differential equations of motion and solved numerically using the Runge-Kutta algorithm. The results are compared with the solution...
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Utulization of biomass for heating purposes in pomeranian region
PublicationW publikacji przedstawiono analizę potencjału użycia odnawialnych źródeł energii do produkcji ciepła w regionie pomorskim. Każde miasto regionu zostało oszacowane pod względem potencjału użycia odnawialnych źródeł energii. Dwa obszary miejskie cechują się tym, że mają potencjał pokrycia swojego zapotrzebowania na ciepło tylko ze słomy, czyli możemy rozpatrywać produkcję ciepła z kotłów opalanych słomą jako 100% potencjalne zapotrzebowanie...
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Planowanie zrównoważonego transportu miejskiego w Gdyni
PublicationWzrastający popyt na transport indywidualny jest jedną z przyczyn zatłoczenia sieci ulicznej, a co za tym idzie zwiększenia uciążliwości środowiskowych (emisja spalin i hałas) oraz pogorszenia bezpieczeństwa ruchu drogowego (wzrost liczby zdarzeń drogowych). Pojawia się zatem konieczność działań, które ograniczą negatywne skutki rozwoju motoryzacji i zaczną je niwelować. W referacie przedstawiono program działań, które miasto Gdynia...
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Kampus uniwersytecki w strukturze śródmieścia
PublicationKampus uniwersytecki uznawany jest na świecie jako jeden z najistotniejszych generatorów miejskiej przestrzeni publicznej. Stąd szczególnego znaczenia nabiera sposób wykorzystania tego potencjału dla rewitalizacji struktur śródmiejskich. Kampusy otwiera się na miasto integrując je poprzez atrakcyjny system przestrzeni publicznej, wprowadza się do programu funkcjonalnego ośrodków uniwersyteckich ofertę popularno-naukową atrakcyjną...
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Dzielnica reprezentacyjna Gdyni
PublicationKoncepcja Dzielnicy Reprezentacyjnej Gdyni ma historię tak długą jak samo miasto. Już pierwsze plany urnanistyczne z 1926 r. przewidywały jej budowę na południe od portu, jednakże później uległy one zmianie. Szeroko dyskutowany i bardzo interesujący projekt tej dzielnicy powstał w 1938 r., lecz zdołano zaledwie rozpocząć jego realizację przed 1939 r. Projekt ten po wojnie zarzucony odradza się w innym kształcie w czasach współczesnych.
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Evaluation of thermal cracking probability for asphalt concretes with high percentage of RAP
PublicationThe paper presents determination of the probability of thermal cracking of asphalt mixtures with different reclaimed asphalt pavement (RAP) content on the basis of laboratory tests and analytical evaluation using thermal stress development method. Probability was evaluated taking into consideration: the type and gradation of the mixture and the quality and content of RAP. Thermal stresses were determined using two models: elastic and...
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On the material symmetry group for micromorphic media with applications to granular materials
PublicationWithin the framework of the theory of nonlinear elastic micromorphic continua we introduce the new definition of the local material symmetry group. The group consists of ordered triples of second- and third-order tensors describing such changes of a reference placement that cannot be recognized with any experiment. Using the definition we characterize the micromorphic isotropic media, micromorphic fluids, solids and special intermediate...