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Search results for: MULTIPATH PROPAGATON
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Acoustic heating produced in resonators filled by a newtonian fluid
PublicationAcoustic heating in resonators is studied. The governing equation of acoustic heating is derived by means of the special linear combination of conservation equations in differential form, allowing the reduction of all acoustic terms in the linear part of the final equation, but preserving terms belonging to the thermal mode responsible for heating. This equation is instantaneous and includes nonlinear acoustic terms that form a...
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High frequency dynamics of an isotropic Timoshenko periodic beam by the use of the Time-domain Spectral Finite Element Method
PublicationIn this work results of numerical simulations and experimental measurements related to the high frequency dynamics of an aluminium Timoshenko periodic beam are presented. It was assumed by the authors that the source of beam structural periodicity comes from periodical alterations to its geometry due to the presence of appropriately arranged drill-holes. As a consequence of these alterations dynamic characteristics of the beam...
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The effect of external load on ultrasonic wave attenuation in steel bars under bending stresses
PublicationThe stress state in deformed solids has a significant impact on the attenuation of an ultrasonic wave propagating through the medium. Measuring a signal with certain attenuation characteristics can therefore provide useful diagnostic information about the stress state in the structure. In this work, basic principles behind a novel attenuation-based diagnostic framework are introduced. An experimental study on steel bars under three-point...
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Hydraulic analysis of causes of washout of Gdynia-Orłowo seashore during the flood in the Kacza river estuary
PublicationIn July 2016 in the Three-city agglomeration a rainfall episode of over a day duration and 150 mm summary rainfall height, occurred. This situation, extreme as for Polish conditions, caused significant freshets in rivers and streams running into Gdansk Bay, the Baltic Sea, and serving as collectors of rainfall waters for the sea-coast towns. In many areas of the Three-city flood phenomena and overflows took place. The flood also...
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Structure, luminescent properties and FDTD simulation of TeO2-BaO-Bi2O3-Ag:Ln3+ glass-ceramics system
PublicationTeO2-BaO-Bi2O3-Ag glass systems (TBB) co-doped with terbium and europium ions have been successfully synthesized through conventional melt-quenching technique. Heat treatment procedure at 350 °C has been conducted in order to synthesize silver nanoparticles embedded in TBB glass matrix. Structural measurements involved XRD studies that revealed no crystallization of glass structure after heat treatment at elevated temperatures....
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Memetic approach for multi-objective overtime planning in software engineering projects
PublicationSoftware projects often suffer from unplanned overtime due to uncertainty and risk incurred due to changing requirement and attempt to meet up with time-to-market of the software product. This causes stress to developers and can result in poor quality. This paper presents a memetic algorithmic approach for solving the overtime-planning problem in software development projects. The problem is formulated as a three-objective optimization...
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Broadband communication solutions for maritime ITSs: Wider and faster deployment of new e-navigation services
Publicationn its initial part, the paper presents an overview of popular technologies and systems currently developed or employed in maritime communication. These solutions are used to provide both ship-to-ship and ship-to-shore communication for the purpose of supporting specific services, often dedicated to maritime safety and e-navigation. Utility of such communication systems have been thoroughly verified over the years and their strengths...
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GPS-derived height changes in diurnal and sub-diurnal timescales
PublicationThis paper describes the research concerning precise short-time GPS solutions conducted in the Centre of Applied Geomatics, Military University of Technology, Warsaw, Poland. The data from ASG-EUPOS (Polish Active Geodetic Network) was processed using Bernese 5.0 software and EPN (EUREF Permanent Network) standards and models. In this study, the adapted 3-hour observation window is shifted every hour for obtaining hourly geocentric...
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Radio Channel Measurements in Off-Body Communications in a Ferry Passenger Cabin
PublicationThis paper presents an off-body radio channel measurements in a ferry passenger cabin at 2.45 GHz band, for static sleeping scenarios with different body orientation and on-body antennas placements, and also for upper and lower sleeping berths. The measurements have been performed with two types of on-body wearable receiving antennas: FlexPIFA (flexible planar inverted F antenna), and FlexNotch (flexible adhesive-backed notch antenna)...
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Natural convective heat transfer from isothermal cuboids
PublicationThe paper presents results of theoretical and experimental investigations of the convective heat transfer from isothermal cuboid. The analytical solution was performed taking into account complete boundary layer length and the manner of its propagation around isothermal cuboid. It arises at horizontal bottom surface and grows on vertical lateral surface of the block. After changing its direction, the boundary layer occurs above...
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Pounding Between Superstructure Segments in Multi-Supported Elevated Bridge with Three-Span Continuous Deck Under 3D Non-Uniform Earthquake Excitation
PublicationReports after severe ground motions show that the earthquake-induced structural pounding may lead to significant damage in elevated bridges. The aim of this paper is to analyse pounding between superstructure segments of a highway elevated bridge with three-span continuous deck under 3D non-uniform earthquake excitation, which is induced by spatial seismic effects related to the propagation of seismic wave. The conditional stochastic...
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Mechanical Properties of Additively Manufactured Polymeric Materials—PLA and PETG—For Biomechanical Applications
PublicationThe study presented herein concerns the mechanical properties of two common polymers for potential biomedical applications, PLA and PETG, processed through fused filament fabrication (FFF)—Material Extrusion (ME). For the uniaxial tension tests carried out, two printing orientations—XY (Horizontal, H) and YZ (Vertical, V)—were considered according to the general principles for part positioning, coordinates, and orientation typically...
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Investigation of the Efficiency of a Dual-Fuel Gas Turbine Combustion Chamber with a Plasma‒Chemical Element
PublicationThe study is devoted to the possibility of increasing the efficiency of the working process in dual-fuel combustion chambers of gas turbine engines for FPSO vessels. For the first time, it is proposed to use the advantages of plasma‒chemical intensification of the combustion of hydrocarbon fuels in the dual-fuel combustion chambers, which can simultaneously operate on gaseous and liquid fuels. A design scheme of a combustion chamber...
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Person Tracking in Ultra-Wide Band Hybrid Localization System Using Reduced Number of Reference Nodes
PublicationIn this article a novel method of positional data integration in an indoor hybrid localization system combining inertial navigation with radio distance measurements is presented. A point of interest is the situation when the positional data and the radio distance measurements are obtained from less than thee reference nodes and it is impossible to unambiguously localize the moving person due to undetermined set of positional equations....
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Generalization of Kramers-Krönig relations for evaluation of causality in power-law media
PublicationClassical Kramers-Krönig (K–K) relations connect real and imaginary parts of the frequency-domain response of a system. The K–K relations also hold between the logarithm of modulus and the argument of the response, e.g. between the attenuation and the phase shift of a solution to a wave-propagation problem. For square-integrable functions of frequency, the satisfaction of classical K–K relations implies causality in the time domain....
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Assessment of Wide-Sense Stationarity of an Underwater Acoustic Channel Based on a Pseudo-Random Binary Sequence Probe Signal
PublicationThe performances of Underwater Acoustic Communication (UAC) systems are strongly related to the specific propagation conditions of the underwater channel. Designing the physical layer of a reliable data transmission system requires a knowledge of channel characteristics in terms of the specific parameters of the stochastic model. The Wide-Sense Stationary Uncorrelated Scattering (WSSUS) assumption simplifies the stochastic description...
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SPECTRAL RESPONSE OF STATIONARY JACK-UP PLATFORMS LOADED BY SEA WAVES AND WIND USING PERTURBATION METHOD
PublicationThe paper addresses non-linear vibrations of offshore jack-up drilling platforms loaded by sea waves and wind in their stationary condition using the perturbation method. Non-linearity of dynamic equations of motion for fixed offshore platforms yields from two factors. The first is load excitation generating non-linear velocity coupling in a dynamic system. This coupling is inherent in the modified Morison equation, involving the...
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Non-ergodic fragmentation upon collision-induced activation of cysteine–water cluster cations
PublicationCysteine–water cluster cations Cys(H2O)3,6 + and Cys(H2O)3,6H+ are assembled in He droplets and probed by tandem mass spectrometry with collision-induced activation. Benchmark experimental data for this biologically important system are complemented with theory to elucidate the details of the collisioninduced activation process. Experimental energy thresholds for successive release of water are compared to water dissociation energies...
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Marine polymers in tissue bioprinting: Current achievements and challenges
PublicationBioprinting has a critical role in tissue engineering, allowing the creation of sophisticated cellular scaffolds with high resolution, shape fidelity, and cell viability. Achieving these parameters remains a challenge, necessitating bioinks that are biocompatible, printable, and biodegradable. This review highlights the potential of marine-derived polymers and crosslinking techniques including mammalian collagen and gelatin along...
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Independent dynamics of slow, intermediate, and fast intracranial EEG spectral activities during human memory formation
PublicationA wide spectrum of brain rhythms are engaged throughout the human cortex in cognitive functions. How the rhythms of various low and high frequencies are spatiotemporally coordinated across the human brain during memory processing is inconclusive. They can either be coordinated together across a wide range of the frequency spectrum or induced in specific bands. We used a large dataset of human intracranial electroencephalography...
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LIGHT POLLUTION IN THE CONTEXT OF THREATS TO THE WILDLIFE CORRIDORS
PublicationAccess to remote sensing night-time imagery allows for modeling of light pollution Increasingly, data on the propagation of artificial light are a source of interesting information for different fields of science and affect the planning of economic development. The article presents the problem of light pollution in the context of threats to the wildlife corridors in Poland. Wildlife corridors are areas that allow safe migration...
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Distributed System For Noise Threat Evaluation Based On Psychoacoustic Measurements
PublicationAn innovative system designed for the continuous monitoring of acoustic climate of urban areas was presentedin the paper. The assessment of environmental threats is performed using online data, acquired through a grid ofengineered monitoring stations collecting comprehensive information about the acoustic climate of urban areas.The grid of proposed devices provides valuable data for the purpose of long and short time acoustic climateanalysis....
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Artificial Neural Networks as an architectural design tool- generating new detail forms based on the Roman Corinthian order capital
PublicationThe following paper presents the results of the research in the field of the machine learning, investigating the scope of application of the artificial neural networks algorithms as a tool in architectural design. The computational experiment was held using the backward propagation of errors method of training the artificial neural network, which was trained based on the geometry of the details of the Roman Corinthian order capital....
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Anisotropy and compaction gradient assessment on rammed earth specimens through sonic tomography approach
PublicationRammed earth is a traditional construction technique that has recently gained attention because of its benefits from an ecological perspective. The conservation of the existing valuable cultural heritage sites and the quality control of new constructions built with this material require the development and application of practical inspection techniques. This paper explores the application of sonic tests and sonic tomography as...
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Implementation of Non-Probabilistic Methods for Stability Analysis of Nonlocal Beam with Structural Uncertainties
PublicationIn this study, a non-probabilistic approach based Navier’s Method (NM) and Galerkin Weighted Residual Method (GWRM) in term of double parametric form has been proposed to investigate the buckling behavior of Euler-Bernoulli nonlocal beam under the framework of the Eringen's nonlocal elasticity theory, considering the structural parameters as imprecise or uncertain. The uncertainties in Young’s modulus and diameter of the beam are...
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A spline-based FE approach to modelling of high frequency dynamics of 1-D structures
PublicationIn this paper a computational methodology leading to the development of a new class of FEs, based on the application of continuous and smooth approximation polynomials, being splines, has been presented. Application of the splines as appropriately defined piecewise elemental shape functions led the authors to the formulation of a new approach for FEM, named as spFEM, where contrary to the well-known NURBS approach, the boundaries...
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One-Step Combustion Synthesis of Novel Nanocarbons via Magnesiothermic Reduction of Carbon-Containing Oxidants
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Maturity Mismatch in the Polish Banking System and its Impact on the Economy
PublicationIn the article maturity mismatch in the Polish banking system is estimated based on the publicly available data. Then the impact on the economy is discussed. Based on Polish central bank’s data it may be estimated that between 1996 and 2012 the maturity gap increased significantly – average residual maturity of assets exceeds 6 years in 2012 (less than 2 years in 1996), while that of liabilities remains below 1 year. The gap...
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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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Identification of Parameters Influencing the Accuracy of the Solution of the Nonlinear Muskingum Equation
PublicationTwo nonlinear versions of the Muskingum equation are considered. The difference between both equations relates to the exponent parameter. In the first version, commonly used in hydrology, this parameter is considered as free, while in the second version, it takes a value resulting from the kinematic wave theory. Consequently, the first version of the equation is dimensionally inconsistent, whereas the proposed second one is consistent. It...
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Independent dynamics of low, intermediate, and high frequency spectral intracranial EEG activities during human memory formation
PublicationA wide spectrum of brain rhythms are engaged throughout the human cortex in cognitive functions. How the rhythms of various frequency ranges are coordinated across the space of the human cortex and time of memory processing is inconclusive. They can either be coordinated together across the frequency spectrum at the same cortical site and time or induced independently in particular bands. We used a large dataset of human intracranial...
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Effects of consecutive apneas on pial artery pulsation and subarachnoid width in healthy subjects
PublicationHypercapnia is known to dilate the pial artery, disrupt cerebral autoregulation and increase pial artery pulsation. The cerebral blood flow velocity (CBFV) response to hypercapnia is biphasic. Below the threshold for the increase of blood pressure (BP) with carbon dioxide partial pressure (pCO2), the CBFV measurement reflects vascular reactivity to pCO2 alone at a constant BP. Above this threshold, the CBFV measurement provides...
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OOA-modified Bi-LSTM network: An effective intrusion detection framework for IoT systems
PublicationCurrently, the Internet of Things (IoT) generates a huge amount of traffic data in communication and information technology. The diversification and integration of IoT applications and terminals make IoT vulnerable to intrusion attacks. Therefore, it is necessary to develop an efficient Intrusion Detection System (IDS) that guarantees the reliability, integrity, and security of IoT systems. The detection of intrusion is considered...
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Designing a High-sensitivity Microscale Triple-band Biosensor based on Terahertz MTMs to provide a perfect absorber for Non-Melanoma Skin Cancer diagnostic
PublicationNon-melanoma skin cancer (NMSC) is among the most prevalent forms of cancer originating in the top layer of the skin, with basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) being its primary categories. While both types are highly treatable, the success of treatment hinges on early diagnosis. Early-stage NMSC detection can be achieved through clinical examination, typically involving visual inspection. An alternative,...
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Derecho Evolving from a Mesocyclone—A Study of 11 August 2017 Severe Weather Outbreak in Poland: Event Analysis and High-Resolution Simulation
PublicationThis study documents atmospheric conditions, development, and evolution of a severe weather outbreak that occurred on 11 August 2017 in Poland. The emphasis is on analyzing system morphology and highlighting the importance of a mesovortex in producing the most significant wind damages. A derecho-producing mesoscale convective system (MCS) had a remarkable intensity and was one of the most impactful convective storms in the history...
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Nondestructive methods complemented by FEM calculations in diagnostics of cracks in bridge approach pavement
PublicationNondestructive methods of road pavement diagnostics are an alternative to traditional approach to pavement failure investigation. The article presents a detailed multidisciplinary inspection carried out using ground-penetrating radar (GPR), laser scanning technology and finite element method (FEM) calculations. It was done in order to assess the factors that contributed to occurrence of premature cracks of a bridge approach pavement....
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Sensitive Demonstration of the Twin-Core Couplers including Kerr Law Non-Linearity via Beta Derivative Evolution
PublicationTo obtain new solitary wave solutions for non-linear directional couplers using optical meta-materials, a new extended direct algebraic technique (EDAT) is used. This model investigates solitary wave propagation inside a fiber. As a result, twin couplers are the subject of this study. Kerr law is the sort of non-linearity addressed there. Because it offers solutions to problems with large tails or infinite fluctuations, the resulting...
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Swapping Space for Time: An Alternative to Time-Domain Interferometry
PublicationYoung's double-slit experiment [1] requires two waves produced simultaneously at two different points in space. In quantum mechanics the waves correspond to a single quantum object, even as complex as a big molecule. An interference is present as long as one cannot tell for sure which slit is chosen by the object. The more we know about the path, the worse the interference. In the paper we show that quantum mechanics allows for...
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Open extensive IoT research and measurement infrastructure for remote collection and automatic analysis of environmental data.
PublicationInternet of Things devices that send small amounts of data do not need high bit rates as it is the range that is more crucial for them. The use of popular, unlicensed 2.4 GHz and 5 GHz bands is fairly legally enforced (transmission power above power limits cannot be increased). In addition, waves of this length are very diffiult to propagate under field conditions (e.g. in urban areas). The market response to these needs are the...
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Quantitative Risk Assessment in Construction Disputes Based on Machine Learning Tools
PublicationA high monetary value of the construction projects is one of the reasons of frequent disputes between a general contractor (GC) and a client. A construction site is a unique, one-time, and single-product factory with many parties involved and dependent on each other. The organizational dependencies and their complexity make any fault or mistake propagate and influence the final result (delays, cost overruns). The constant will...
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The advanced monitoring as a key factor for appropriate optimization and control of full-scale activated sludge systems – case study Debogorze WWTP.
PublicationComputer simulation has become a helpful tool in wastewater treatment systems performance and effectiveness analysis. Advanced monitoring, by using appropriate software, enables to create a mathematical model of a real wastewater treatment plant (WWTP), run a simulation and subsequently interpret results under various conditions. An operation of WWTP is usually controlled by global parameters such as flow, solids retention time,...
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Influence of bitumen type on cracking resistance of asphalt mixtures used in pavement overlays
PublicationCracking is one of the predominant distresses occurring in flexible pavements, especially in old pavements that were rehabilitated with an asphalt overlay. In such cases asphalt mixtures should be designed to ensure high resistance to reflective cracking because new asphalt layers are exposed to existing cracks of the old pavement. The nature of these cracks can be various (transverse, longitudinal as well as crazy cracking). One...
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Microseismic Monitoring of Hydraulic Fracturing - Data Interpretation Methodology With an Example from Pomerania
PublicationMicroseismic monitoring is a method for localizing fractures induced by hydraulic fracturing in search for shell gas. The data is collected from an array of geophones deployed on the surface or underground. Ground vibrations are recorded and analysed for fracture location, magnitude and breakage mechanism. For successful microseismic monitoring one need a velocity model of underlying formations. The model is further tuned with...
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Impact response of novel layered two stage fibrous composite slabs with different support type
PublicationThe performance of novel Layered Two Stage Fibrous Composite slabs (LTSFC) was pioneered under falling mass collisions using a combined experimental and numerical study. Such LTSFC slabs consist of three layers with and without the insertion of glass fibre mesh between the layers. LTSFC techniques were used to fabricate the composite slabs with three layers including 3%, 1.5%, and 3% of fibre content for the top, middle, and...
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Game Theory Analysis of Bidding for a Construction Contract
PublicationThe authors are concerned with a bidding problem. There are two companies (P1 and P2) bidding for a highway construction project. In order to be more competitive, P1 considers buying a new gravel pit near the construction site. The basic cost of the pit is known to both companies. However, there is also an additional, hidden, cost (C) known only to P1. P2 is uncertain whether the hidden cost is C = 0 or C = x. P1 plans to bid for...
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Bounds on the Cover Time of Parallel Rotor Walks
PublicationThe rotor-router mechanism was introduced as a deterministic alternative to the random walk in undirected graphs. In this model, a set of k identical walkers is deployed in parallel, starting from a chosen subset of nodes, and moving around the graph in synchronous steps. During the process, each node maintains a cyclic ordering of its outgoing arcs, and successively propagates walkers which visit it along its outgoing arcs in...
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Broken Rotor Symptons in the Sensorless Control of Induction Machine
PublicationInverter fed sensorless controlled variable speed drives with induction machine are widely used in the industry applications, also in wind power generation and electric vehicles. On-line self diagnostic systems implementation is needed for early stage fault detection and avoiding a critical fault. Diagnostic algorithms in modern DSP-based controllers can operate simultaneously with control system functions. In the closed-loop controlled...
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A Comprehensive Survey on Antennas On-Chip Based on Metamaterial, Metasurface, and Substrate Integrated Waveguide Principles for Millimeter-Waves and Terahertz Integrated Circuits and Systems
PublicationAntennas on-chip are a particular type of radiating elements valued for their small footprint. They are most commonly integrated in circuit boards to electromagnetically interface free space, which is necessary for wireless communications. Antennas on-chip radiate and receive electromagnetic (EM) energy as any conventional antennas, but what distinguishes them is their miniaturized size. This means they can be integrated inside...
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The role of organic and mineral constituents on kerogen transformation ratio
PublicationThe main aim of this dissertation is to determine the role of mineral and organic matter constituents in kerogen transformation ratio. Practical aspects of the work include application of the results in the assessment of hydrocarbon production potential; to make process of hydrocarbon recovery more predictable consistent and efficient. The work used shale from the Vaca Muerta formation from the Nequen basin in Argentina. The formation...
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Has EGNOS its own place in maritime navigation?
PublicationGNSS (in fact it usually means GPS) is at the moment the fundamental means of positioning for any variants of navigation. However some attributes of it can be not sufficient for every users or in some tasks, so there are any cases when this system needs support. From the mariner point of view pure GPS properties perfectly fulfils expectations of sailors at the open sea, however there are lot of cases, when accuracy of the system...