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Search results for: ZIPF’S LAW.
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On deterministic procedures for low-cost multi-objective design optimization of miniaturized impedance matching transformers
PublicationPurpose This paper aims to investigate deterministic strategies for low-cost multi-objective design optimization of compact microwave structures, specifically, impedance matching transformers. The considered methods involve surrogate modeling techniques and variable-fidelity electromagnetic (EM) simulations. In contrary to majority of conventional approaches, they do not rely on population-based metaheuristics, which permit lowering...
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A universal NDT method for examination of low energy impact damage in CFRP with the use of TLC film
PublicationThe article presents an attempt to use a sheet of laminated thermochromic liquid crystal film (TLC film) for non-destructive testing of the impact damage (energy values: 1J, 2J, 3J and 4J) in carbon fibre-reinforced polymer (CFRP). This is a new, alternative NDT approach based on the thermo-optical effect. The main advantages of this method are a) the low cost of TLC film, b) the low cost of recording devices due to the usage of...
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Impact of Low Switching-to-Fundamental Frequency Ratio on Predictive Current Control of PMSM: A simulation study
PublicationPredictive current control algorithms for permanent magnet synchronous (PMSM) drives rely on an assumption that within short intervals motor currents can be approximated with linear functions. This approximation may result either from discretizing the motor model or from simplifications applied to the continuous-time model. As the linear current approximation has been recognized as inaccurate in case when the drive operates with...
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Comparison of the impact test and the harmonic test in measurements of natural resonant frequencies of circular saw blades
PublicationIn this paper results of measurements of natural resonant frequencies of circular saw blades with the impact test and the harmonic test are presented. Comparison of these two methods revealed that during testing of circular saw blades, in which bodies the open and closed notches (cuts) for cleaning of knives are present, with the harmonic test method it has been observed appearing of quasi-twin resonant frequencies, whereas the...
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Las pełen muzyki:Unikatowe walory architektury Opery Leśnej w Sopocie, dawniej i obecnie
PublicationZakończona sukcesem współczesna modernizacja architektury , konstrukcji i elementów nowej estetyki kultowego obiektu Opery Leśnej w Sopocie daje podstawę do snucia optymistycznych wniosków na temat przyszłości rozwoju kultury muzycznej w szerokim tego słowa znaczeniu Cała.przestrzeń nowoczesnego funkcjonalnego obiektu o innowacyjnej konstrukcji zadaszenia nad sceną i powiększoną 5000 miejs- widownią ,jest nową atrakcja...
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Low-Coherence Interferometer with Nanocrystalline Diamond Films with Potential Application to Measure Small Biological Samples
PublicationThe study investigates a case of a low-coherence fiber-optic Fabry–Prerot interferometer with a nanocrystalline diamond (NCD) mirror. The method of achieving double density of interference fringes is proposed by the application of birefringent material in the cavity of the interferometer. It can be used to reduce sample volume in comparison to conventional interferometers. The use of a biocompatible diamond mirror makes it specifically...
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On low-fidelity models for variable-fidelity simulation-driven design optimization of compact wideband antennas
PublicationThe paper addresses simulation-driven design optimization of compact antennas involving variable-fidelity electromagnetic (EM) simulation models. Comprehensive investigations are carried out concerning selection of the coarse model discretization density. The effects of the low-fidelity model setup on the reliability and computational complexity of the optimization process are determined using a benchmark set of three ultra-wideband...
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Study of Aliphatic Polyurethanes by the Low-Field 1H NMR Relaxometry Method with the Inversion of the Integral Transformation
PublicationIn this paper, the distributions of the 1H nuclear magnetic resonance (NMR) spin–lattice and spin–spin relaxation times are used to characterize the mobility of different sections of macromolecules of aliphatic polyurethanes and the cross-linking density of polymer chains. The NMR relaxometry method with inversion of integral transformation is applied to study the effect of poly (ethylene glycol) and glycerol phosphate calcium...
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Low temperature growth of diamond films on optical fibers using Linear Antenna CVD system
PublicationIt is not trivial to achieve a good quality diamond-coated fibre interface due to a large difference in the properties and composition of the diamond films (or use coating even) and the optical fibre material, i.e. fused silica. One of the biggest problems is the high temperature during the deposition which influences the optical fibre or optical fibre sensor structure (e.g. long-period gratings (LPG)). The greatest advantage of...
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Influence of laser processing of the low alloy medium carbon structural steel on the development of the fatigue crack
PublicationThe paper contains the results of the structural analysis, hardness tests and fatigue tests conducted for the medium carbon structural steel with low content of Cr and Ni after its processing with CO2 laser beam. Pre-cracks were made in the round compact tension (RCT) specimen used for fatigue test. Next, four paths, parallel to each other, were melted on both sides of the samples using a laser beam. The paths were perpendicular...
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Application of thin diamond films in low-coherence fiber-optic Fabry Pérot displacement sensor
PublicationThe novel fiber-optic low coherence sensor with thin diamond films is demonstrated. The undoped and boron-doped diamond films were elaborated by the use of the microwave plasma enhanced chemical vapor deposition (μPE CVD) system. The optical signal from the Fabry–Pérot cavity made with the application of those thin films is sensitive to displacement. The sensor characterization was made in the range of 0–600 μm. The measurements...
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A BRIEF REVIEW AND COMPARISON OF SELECTED EXPERIMENTAL METHODS FOR MEASURING NATURAL FREQUENCIES OF CIRCULAR SAW BLADES
PublicationDifferent methods for the empirical determination of the natural frequencies of circular saw blades are presented. Stationary methods, such as the harmonic and impulse tests, are discussed and the results of related comparison are given. The comparison of the methods revealed their degree of practical usefulness and their accuracy in determining natural frequencies. A combination of specific methods is proposed, which should allow...
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Factors determining accumulation of bisphenol A and alkylphenols at a low trophic level as exemplified by mussels Mytilus trossulus
PublicationThe aim of the study was to investigate abiotic and biotic factors influencing the accumulation of endocrine disrupting compounds (EDCs) such as bisphenol A (BPA), 4-tert-octylphenol (OP) and 4- nonylphenol (NP) in mussels Mytilus trossulus from the Gulf of Gdansk (Southern Baltic). The key abiotic factor influencing BPA, OP and NP accumulation in mussels is their hydrophilicity/lipophilicity, which affects their main assimilation...
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A new method of fault loop resistance measurement in low voltage systems with residual current devices
PublicationThis paper presents a new method of fault loop resistance measurement in low voltage systems with residual current devices. The method enables measuring fault loop resistance without nuisance tripping of residual current devices, by application an unconventional waveform of measurement current. It is important for proper verification of the effectiveness of protection against electric shock.
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Rodowód Katedry Energoelektroniki i Maszyn Elektrycznych Politechniki Gdańskiej z lat 1945-1969
PublicationPrzedstawiono sylwetki pierwszych powojennych profesorów Wydziału Elektrycznego PG, którzy tworzyli zespoły naukowe i laboratoria do prowadzenia badań i nauczania konstrukcji maszyn elektrycznych, napędów elektrycznych, techniki cyfrowej i energoelektroniki. W wyniku ich działalności oraz przemian organizacyjnych Politechniki Gdańskiej powstała na Wydziale Elektrotechniki i Automatyki, Katedra Energoelektroniki i Maszyn Elektrycznych.
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Low-Cost Unattended Design of Miniaturized 4 × 4 Butler Matrices with Nonstandard Phase Differences
PublicationDesign of Butler matrices dedicated to Internet of Things and 5th generation (5G) mobile systems—where small size and high performance are of primary concern—is a challenging task that often exceeds capabilities of conventional techniques. Lack of appropriate, unified design approaches is a serious bottleneck for the development of Butler structures for contemporary applications. In this work, a low-cost bottom-up procedure for...
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Machine-Learning-Powered EM-Based Framework for Efficient and Reliable Design of Low Scattering Metasurfaces
PublicationPopularity of metasurfaces has been continuously growing due to their attractive properties including the ability to effectively manipulate electromagnetic (EM) waves. Metasurfaces comprise optimized geometries of unit cells arranged as a periodic lattice to obtain a desired EM response. One of their emerging application areas is the stealth technology, in particular, realization of radar cross section (RCS) reduction. Despite...
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The Toolbox of Methods for Multidirectional Characterization of Dietary Nucleic Acids; Verification for Raw and Processed Food Products
PublicationCurrently, the nutritional value of food is associated mainly with components such as proteins, carbohydrates, and lipids. However, another important macromolecules present in many foods are dietary nucleic acids (dietNA), i.e., DNA as well as both coding and non-coding RNAs. In the context of food chemistry and nutrition, dietNA are nowadays vastly neglected. In consequence, there are no dedicated methodologies to characterize...
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Mild poikilocapnic hypoxia increases very low frequency haemoglobin oxygenation oscillations in prefrontal cortex
PublicationBackground: The aim of the study was to investigate the effect of mild cerebral hypoxia on haemoglobin oxygenation(HbO2), cerebrospinal fluid dynamics and cardiovascular physiology. To achieve this goal, four signals were recorded simultaneously: blood pressure, heart rate / electrocardiogram, HbO2 from right hemisphere and changes of subarachnoid space (SAS) width from left hemisphere. Signals were registered from 30 healthy,...
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Fracture Areas Quantitative Investigating of Bending-Torsion Fatigued Low-Alloy High-Strength Steel
PublicationIn this study, the impact of pseudo-random non-proportional bending-torsion fatigue loadings proportion on the fatigue life and the fracture surface topography was analyzed. Investigation was carried out for 24 specimens made of S355J2 steel with 11 different ratios of maximum stresses λ. For these cases, after the fatigue tests, the surface topography measurements were carried out using an optical profilometer, using the focus...
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The Influence of Low-Temperature Disintegration on the Co-Fermentation Process of Distillation Residue and Waste-Activated Sludge
Publication: Innovative low-temperature disintegration (process temperature 55 ◦C and oxygen concentration 0.2 mg/dm3 ) can be an economically rational technology to intensifying energy production from renewable sources. The proposed process can achieve a degree of disintegration—under optimal conditions—of about 50%, which is excellent when compared with other methods of feed pre-treatment. The low-temperature disintegration of distillation...
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Harnessing digital technologies for poverty reduction. Evidence for low-income and lower-middle income countries
PublicationThis paper contributes to understanding the relationship between ICT deployment and poverty alleviation in developing countries. It assess the digital technologies contribution to poverty reduction, through different channels of impact, like education, labor market, income and ICTtrade related activities. Using the sample of 40 developing countries between 1990 and 2019, it relies on macro data extracted from the World Bank Development...
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Theoretical and Actual Feed Per Tooth During Wood Sawing on an Optimizing Cross-Cut Saw
PublicationThe work presents the geometries of circular saw teeth, whose task is to divide the cross-cut of the cutting layer. For efficient machining on a cross-cut saw with high feed speed values (about 1 ms−1) maximal theoretical feeds per tooth are determined. These values were compared with the actual values determined during transverse cutting of pine wood on a special test stands in industrial conditions. In the experiment the rotational...
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Electrochemical oxidation of PFOA and PFOS in landfill leachates at low and highly boron-doped diamond electrodes
PublicationPolyfluorinated alkyl substances (PFASs) may reach landfill leachates (LLs) due to improper waste management. In this study perfluorooctanoate (PFOA) and perfluorooctane sulphonate (PFOS) were used as representatives of PFASs in the decomposition on boron-doped diamond electrodes (BDDs) with high (10k ppm) and low (0.5k ppm) boron doping concentrations. The result shows that although better COD removal efficacies are obtained on...
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REVIEW OF CURRENT RESEARCH ON CHITOSAN AS A RAW MATERIAL IN THREE-DIMENSIONAL PRINTING TECHNOLOGY IN BIOMEDICAL APPLICATIONS
PublicationThree-dimensional (3D) biomaterial manufacturing strategies show an extraordinary driving force for the development of innovative solutions in the biomedical sector, including drug delivery systems, disease modelling and tissue and organ engineering. Due to its remarkable and promising biological and structural properties, chitosan has been widely studied for decades in several potential applications in the biomedical field. However,...
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Methodology for determining the elemental composition, as well as energy and ignition properties of the low-sulfur marine fuels
PublicationThe key metrological issue of substance and energy balance in research engines is the precise determination of the elemental composition of the applied fuel and its net calorific value. This makes it possible to calculate the amount of heat brought with the fuel into the combustion chamber, as well as the amount and gas composition of the exhaust. However, to fully assess the energy quality of the fuel used, its ignition properties...
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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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Low-Loss 3D-Printed Waveguide Filters Based on Deformed Dual-Mode Cavity Resonators
PublicationThis paper introduces a new type of waveguide filter with smooth profile, based on specially designed dual-mode (DM) cavity resonators. The DM cavity design is achieved by applying a shape deformation scheme. The coupling between the two orthogonal cavity modes is implemented by breaking the symmetry of the structure, thus eliminating the need for additional coupling elements. The modes operating in the cavity are carefully analyzed...
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Broad Stopband, Low-Loss, and Ultra-Compact Dual-Mode Bandpass Filter Based on HMSIRC
PublicationIn this investigation, an ultra-compact dual-mode bandpass filter (BPF) with a wide stopband re-sponse is realized by using a half-mode substrate-integrated rectangular cavity (HMSIRC). The HMSIRC resonator is designed with a cavity that is rectangular in shape and has metallic vias along three of the sides. The fourth side is open-ended and contains microstrip feed lines. For the purpose of constructing a magnetic wall, a rectangular...
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Low-cost 3D Printed Circularly Polarized Lens Antenna for 5.9 GHz V2X Applications
PublicationThis paper presents design and realization of a circularly polarized antenna consisting of a linearly polarized patch antenna and a 3D printed lens, at the same time performing the functions of wave collimator and a polarizer. The antenna is dedicated for 802.11p systems, as a part of road infrastructure, with operation bandwidth 5.85 - 5.925 GHz. Its realised gain and axial ratio at center frequency 5.9 GHz are 14.3 dBi and 2.17...
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Low-Barrier Hydrogen Bond Determines Target-Binding Affinity and Specificity of the Antitubercular Drug Bedaquiline
PublicationThe role of short strong hydrogen bonds (SSHB) in ligand-target binding remains largely unexplored, thereby hin- dering a potentially important avenue in the rational drug de- sign. Here, we investigate the interaction between bedaquiline (Bq), a potent anti-tuberculosis drug, and the mycobacterial ATP synthase, to unravel the role of a specific hydrogen bond to a conserved acidic residue in the target affinity and specificity....
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Dissolution of Nb-doped hydroxyapatite prepared via low-temperature mechanochemical method: Spectroscopy studies
PublicationCalcium phosphate glass ceramics with nominal hydroxyapatite stoichiometry doped with niobium were synthesized using simple as well as low-temperature mechanochemical method and then in the form of compressed pellet were submitted to the static dissolution process in distilled water for one month. The results of structural analysis, performed mainly on the base of spectroscopic methods such as: infrared absorption spectroscopy,...
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An Optimized Ka-Band Low Profile Dual-Polarized Transmitarray Antenna With 2D Beam Switching
PublicationThis article presents an optimized dual-polarized transmitarray antenna (TA) designed for MIMO applications at the Ka-band, capable of switching beams in two directions. The antenna aperture uses a small unit cell with three layers of Taconic RF-35 dielectric substrates, which can be easily fabricated using PCB technology. The unit cell achieved a 360-degree phase shift and a transmission magnitude exceeding –0.4 dB at 28 GHz....
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Interactions of amphotericin B derivative of low toxicity with biological membrane components - the Langmuir monolayer approach
PublicationMetodą monowarstw Langmuira zbadano naturę oddziaływań nowej pochodnej antybiotyku przeciwgrzybowego amfoterycyny B o niskiej toksyczności, tj. estru metylowego N-metylo-N-D-fruktopiranozyloamfoterycyny B (MF-AME)z komponentami błon biologicznych: ergosterolem, występującym w komórkach grzybowych i cholesterolem występującym w komórkach zwierzęcych oraz z modelowym fosfolipidem DPPC i na tej podstawie stwierdzono, że zróżnicowanie...
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Antimutagenic activity of white cabbage, raw and processed, juices towards food mutagens MeIQx and PhIP.
PublicationPrezentowane badania pokazały, że soki z kapusty wykazują bardzo silne właściwości przeciwutleniające. Najaktywniejszy był sok ze świeżej kapusty, który eliminował działanie użytych mutagenów w ponad 80%. Obróbka kulinarna nieco obniżała przeciwmutagenne właściwości pozostałych soków, ale i tak wykazywały one silne działanie ochronne.
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Badanie egoistycznych zachowań stacji w bezprzewodowej sieci LAN wykorzystującej standard IEEE 802.11.
PublicationProtokół IEEE 802.11 wykorzystywany w bezprzewodowych sieciach LAN ułatwia niekooperacyjne zachowania stacji. Od niedawna przedmiotem badań są zachowania egoistyczne, zwiększające udział pasma stacji kosztem innych użytkowników sieci. W pracy przedstawiono kilka egoistycznych ataków przeciwko protokołowi, w tym poprzez rekonfigurację mechanizmu CSMA/CA. Symulacja wybranych scenariuszy pracy sieci pozwoliła ocenić ilościowo efekty...
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Technical and economic analysis of energy storage in the compressed air technology with low capacity for the production plant
PublicationCompressed air energy storage (CAES) system is a promising technology due to its numerous advantages, including relatively low maintenance cost, a long lifespan and high operational flexibility. This article explores the possibility of designing a CAES power plant as a source of electricity and heat for an existing industrial plant. The study involves the technical analysis of the power plant parameters and the economic analysis...
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Low-Voltage LDO Regulator Based on Native MOS Transistor with Improved PSR and Fast Response
PublicationIn this paper, a low-voltage low-dropout analog regulator (ALDO) based on a native n-channel MOS transistor is proposed. Application of the native transistor with the threshold voltage close to zero allows elimination of the charge pump in low-voltage regulators using the pass element in a common drain configuration. Such a native pass transistor configuration allows simplification of regulator design and improved performance,...
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Experimental study of the fuel jet combustion in high temperature and low oxygen content exhaust gases
PublicationPrzeprowadzono badania eksperymentalne spalania pojedynczego strumienia paliwa gazowego. Paliwo podawano współosiowo do generowanych przez konwencjonalny palnik gazowy spalin o wysokiej temperaturze i niskiej zawartości tlenu. Badano wpływ zawartości tlenu w utleniaczu na widzialność płomienia i skład produktów spalania.
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15 lat wspólnych działań na rzecz poprawy bezpieczeństwa ruchu drogowego w Polsce
PublicationPrzegląd działań prewencyjnych na rzecz poprawy bezpieczeństwa ruchu drogowego w Polsce w ciągu ostatnich 15 lat. Początek działań systemowych; programy działań głównych partnerów realizacji projektu GAMBIT.
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The use of Preston equation to determine material removal during lap-grinding with electroplated CBN tools
PublicationGrinding executed in a lapping configuration is an alternative finishing process benefiting from both grinding and free-abrasive machining, while minimizing the heat effect impact. Electroplated tools can be effectively used in different abrasive processes, including high-speed grinding, however, the assessment of machining performance over time is a key factor in their correct use to achieve satisfactory technological results....
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Washboarding during cutting on frame sawing machines II. Experimental study of the saw blade behaviour
PublicationPraca jest swego rodzaju suplementem do referatu przedstawianego na 15th Inernational Wood Machining Seminar w Los Angeles, CA, USA. Opisano uzyskane wyniki badań doświadczalnych prowadzonych w oparciu o plan badań Hartley`a.Czynnikami badanymi były: naprężenia napinające brzeszczotu piły, częstotliwość skoków ramy piłowej oraz wysokość cięcia przedmiotu obrabianego. Czynnikami wynikowymi były: wysokość sfalowania powierzchni oraz...
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Conception of on-line lamella´s thickness monitoring system for resawing process on sash-gangs saw
PublicationPrzedstawiono układ do automatycznego pomiaru grubości lameli po cięciu na pilarkach ramowych. Pomiar odbywa się metodą bezstykową za pomocą ultra precyzyjnych laserowych sensorów przemieszczeń. Sygnały z sensorów po obrobieniu za pomocą specjalnego oprogramowania były podstawą do oceny jakości wykonania lameli. Próby cięcia wykonano na pilarce ramowej PRW15M na Politechnice Gdańskiej, a pomiary na Shimane University w Matsue (Japonia)....
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Device characteristics extraction by low frequency noise measurements; Someresults on the state-of-the-art MOSFET´s
PublicationPrzedstawiono wyniki pomiarów i analizy szumów tranzystorów MOSFET z izolatorem bramki wykonanym z SiO2 i HfO2. Wyniki pomiarów wykorzystano do oszacowania gęstości aktywnych stanów na powierzchni użytego tlenku i porównano z wynikami otrzymanymi metodą charge-pumping.
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Geometrical conditions of saw blade`s entering into and going out of material during wood cutting
PublicationW pracy przedstawiono analizę geometrycznych warunków wejścia i wyjścia ostrza piły z materiału obrabianego przy przecinaniu drewna. Przedstawiono czasowy i przestrzenny rozkład geometrycznych parametrów wejścia i wyjścia ostrza i ich wpływ na trwałość ostrzy i dokładność przecinania.
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La sfida di "Re Cotone". Una nuova storia del capitalismo attraverso la storia delle commodities?
PublicationThe article is divided into two parts. In the first one, it highlights the role of commodities in real economy and it observes the coincidence of their price increase after 2003 and their importance as a research topic particularly in the framework of global history. In the second one, it propose a comparative analysis of two recent books on cotton, considering similarities and differences of their approaches, and the difficult...
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L'economia mondiale dopo la guerra fredda
PublicationChe cosa è successo negli equilibri economici mondiali a partire dal 1989 e dalla dissoluzione del vecchio ordine sovietico? Dopo aver esaminato gli Usa e i suoi competitori asiatici, Giappone e Cina, il libro si concentra sull’Europa e sulle grandi trasformazioni portate dalla riunificazione tedesca, da Maastricht e dalla nascita dell’euro. Infine analizza, nell’ambito della globalizzazione, il ruolo dei BRICS, lo sviluppo economico...
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Pt-rich intermetallic APt8P2 (A = Ca and La)
PublicationThe combination of experimental and theoretical investigation of two new Pt-rich intermetallic compounds: APt8P2 (A = Ca and La) is presented, including solid-state synthesis, crystal structure determination, physical properties characterization and chemical bonding analysis. APt8P2 was obtained through the high-temperature pellet synthesis. According to both single crystal and powder X-ray diffraction results, APt8P2 crystallize...
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La fine di un grande sogno
PublicationIl contributo esamima le cause che portarono alla fine dell'Unione sovietica, i meccanismi per il passaggio all'economia di mercato e il nuovo ruolo dello Stato nell'economia russa T
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Fixed point indices of iterates of a low-dimensional diffeomorphism at a fixed point which is an isolated invariant set
PublicationLet f be an R^n-diffeomorphism, where n = 2, 3, for which {0} is an isolated invariant set. We determine all possible forms of the sequences of fixed point indices of iterates of f at 0, {ind(f n, 0)}_n, confirming in R3 the conjecture of Ruiz del Portal and Salazar (J Differ Equ 249, 989–1013, 2010).