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wszystkich: 2592
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Seafloor Characterisation and Imaging Using Multibeam Sonar Data
PublikacjaThe approach to seafloor characterisation and imaging is presented. It relies on the combined, concurrent use of several techniques of multibeam sonar data processing. The first one is based on constructing the grey-level sonar images of seabed using the backscattering strength calculated for the echoes received in the consecutive beams. Then, the set of parameters describing the local region of sonar image is calculated. The second...
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Investigation of electrocatalytic gas sensor properties in presence of chlorine
PublikacjaProperties of sensor based on Nasicon with two round shaped platinum electrodes are investigated. Influence of different chlorine concentrations on the sensor response is presented. Measurements in different temperatures have been performed in order to determine optimal sensor working temperature.
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Hertzian Crack Propagation in Ceramic Rolling Elements
PublikacjaThe properties of ceramics are of most interest to rolling element manufacturers. The influence of ring crack size on rolling contact fatigue failure has been studied using numerical fracture analysis. Such crack are very often found on ceramic bearing balls and decrease fatigue life rapidly. The numerical calculations are based on a three dimensional model for the ring crack propagation. The stress intensity factors along crack...
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Solid Phase Micro-Extraction, a Versatile and Handy Tool in Environmental Trace Organic Analysis, Gets a New Class of Coatings, Polymeric Ionic Liquids
PublikacjaSolid phase microextraction (SPME) fundamentals, characteristics and application are described. The special stress is put on characteristics of sorbents used as SPME fiber coatings. Description of commercially available fibers and the present-day trends in development of new sorbents for SPME are given. Discussion is focused on possibility of application of ionic liquids (IL) and polymeric ionic liquids (PIL) as SPME fiber coatings....
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Computer-aided Analysis of Induced Sheath Voltages in High Voltage Power Cable System
PublikacjaThis paper concerns the effect of configuration of high voltage power cables on induced voltages in their metallic sheaths. One, two or three cables per phase and phase sequence of the cables are considered. Computing of the voltages was performed for a normal operation and in case of earth fault. Various ways of the sheaths bonding are considered as well. Shock hazard and voltage stress of non-metallic outer sheath of cables are...
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Influence of thermal effects on mechanical properties of PVDF-coated fabric
PublikacjaThis paper describes the method of laboratory tests necessary for identification of temperature influence on mechanical properties of polyvinylidene fluoride-coated polyester fabric often used for tensile structures. Two nonlinear model descriptions are investigated. The first one is based on the piece-wise linear relations between stress and strain and the second one on the Murnaghan model of solid behavior. This paper is proposed...
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Nonlinear FEM analysis of irregular shells composed of fiber metal laminates
PublikacjaThe paper deals with the analysis of failure initiation in shells made of Fiber Metal Laminates (FML). The elas-tic material law for orthotropic lamina is stated accounting for asymmetric in-plane stress and strain measures. The asymmetry results from the employed general nonlinear 6-field shell theory where the generalized dis-placements involve the translation and the proper rotation field. The novelty of the presented results...
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Delivery of Ancillary Services in Distribution Power Systems
PublikacjaOne of the technical and organizational challenges the power system faces in deregulated market conditions is to organize an ancillary services market. The growing share of distributed generation of variable (intermittent) energy sources and a change in the market position of consumers, causes the demand for distributed delivery of ancillary services. For this purpose, it is sought to use the ability of the regulatory measures:...
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Rapid surrogate-assisted statistical analysis of compact microstrip couplers
PublikacjaIn this paper, a technique for low-cost statistical analysis and yield estimation of compact microwave couplers has been presented. The analysis is executed at the level of a fast surrogate model representing selected characteristic points of the coupler response that are critical to determine satisfaction/violation of the prescribed design specifications. Because of less nonlinear dependence of the characteristic points on geometry...
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LE STIME ECONOMICHE DELLA CIA E L’IMPREVEDIBILE FINE DELL’URSS
PublikacjaIn this article, we will analyze the debate that took place around the assessments that the CIA gave of the economic situation in the Soviet Union, a clearly decisive key to understanding the overall health of the main political-military opponent of the United States. The article will include the discussions that flared up in the American political establishment starting in 1990, after the fall of the Berlin Wall and the initial...
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Laminaty FRP w budownictwie - charakterystyka materiału i aspekty projektowania
PublikacjaW artykule przedstawiono charakterystykę laminatów polimerowych wzmacnianych włóknami. W pierwszej części zaprezentowano teoretyczne modele materiałowe, podstawowe zależności naprężenie-odkształcenie włókien, matrycy oraz laminatu powstałego przez połączenie obydwu składników. Na tej podstawie sformułowano zalecenia dotyczące praktycznego wykorzystania laminatu w kontekście jego wytężenia w projektowaniu elementów konstrukcyjnych....
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Sensitive determination of isoprostanes in exhaled breath condensate samples with use of liquid chromatography-tandem mass spectrometry
PublikacjaOxidative stress is the hallmark of various inflammatory lung diseases. Increased concentrations of reactive oxygen species in the lungs are reflected by elevated concentrations of oxidative stress markers in the breath, airways, lung tissue and blood. The aim of this work was to develop a method for the fast measurement of F2 isoprostanes in exhaled breath condensate (EBC) samples using equipment which is nowadays available and...
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Regulated Control of the Assembly and Diversity of LPS by Noncoding sRNAs
PublikacjaThe outer membrane (OM) of Gram-negative bacteria is asymmetric due to the presence of lipopolysaccharide (LPS) facing the outer leaflet of the OM and phospholipids facing the periplasmic side. LPS is essential for bacterial viability, since it provides a permeability barrier and is a major virulence determinant in pathogenic bacteria. In Escherichia coli, several steps of LPS biosynthesis and assembly are regulated by the RpoE...
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Remote learning among students with and without reading difficulties during the initial stages of the COVID-19 pandemic
PublikacjaThis article presents the results of a survey on yet under-researched aspects of remote learning and learning difficulties in higher education during the initial stage (March – June 2020) of the COVID-19 pandemic. A total of 2182 students from University of Warsaw in Poland completed a two-part questionnaire regarding academic achievements in the academic year 2019/2020, living conditions and stress related to learning and pandemic,...
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Innovative investment funds and stability of financial systems: Nonparametric study of exchange-traded funds in Europe
PublikacjaThe main aim of the paper is investigation of the potential contribution of exchange-trade funds (ETFs) to the instability of the European financial systems. The paper begins with presentation of the key theoretical concepts with regard to ETFs and financial stability. We discuss the key attributes of ETFs as the innovative category of investment funds, their hypothesized impact on the financial stability as well as briefly describe...
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Injectable poloxamer/graphene oxide hydrogels with well‐controlled mechanical and rheological properties
PublikacjaAlthough significant progress has been made in the design and application of injectable hydrogels for biomedical applications, concurrent control of rheological and mechanical properties of injectable hydrogels has remained as an open challenge to the researchers. In this work, we introduce and put into practice a photo‐curable poloxamer (also known as Pluronic)/graphene oxide (Plu/GO) injectable hydrogel with well‐controlled rheological...
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Impact and stretching standardized tests as useful tools for assessment of viscoelastic behavior for highly rubberized asphalt binder
PublikacjaAsphalt binder is generally identified as a brittle material at low service temperature or under high-speed load, and the brittleness becomes serious after weathering aging. Improving the toughness of asphalt binder through adding high-content of crumb tire rubber is an efficient method to solve this problem. Devulcanized rubber modified asphalt binder (DRMA) with different contents (15–40%) of devulcanized rubber (DR) were prepared...
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Chemical and biological evaluation of antioxidant activity of endogenous redox-active compounds compared to plant-derived exogenous antioxidants
PublikacjaThe research conducted so far has shown that endogenous antioxidants, despite being regarded as the first line of antioxidant defense, may not be sufficient to maintain redox homeostasis in cells exposed to oxidative stress. The results obtained in the doctoral dissertation show that endogenous redox-active compounds were moderate or weak scavengers of ABTS and DPPH radicals, while in cellular setting, their impact on the reducing...
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Image-based numerical modeling of the tensile deformation behavior and mechanical properties of additive manufactured Ti–6Al–4V diamond lattice structures
PublikacjaThis work concerns the numerical modeling of the deformation process and mechanical properties of structures obtained by the additive method laser power bed fusion (LPBF). The investigation uses diamond structures of Ti–6Al–4V titanium implantation alloy with various relative densities. To model the process of tensile deformation of the materials, geometric models were used, mapping the realistic shape of the examined structures....
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Factory Acceptance Test – Strain Gauge Measurement, Report no: WOiO /II/123/2014
PublikacjaTested object was 40 meters long jib and its foundation, placed in Gdansk Shiprepair Yard, manufactured by KMK. The contruction was dedicated to the passenger cruise vessel "Quantum of the Seas" The Strain Gauge measurement in different location and load situation was done in order to validate calculation finite element models used during strength analysis for project. The expertise contains: methodology of the measurements, description...
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Factory Acceptance Test – Strain Gauge Measurement - Report no: WOiO /II/88/2014
PublikacjaTested object was 40 meters long jib and its foundation, placed in Gdansk Shiprepair Yard, manufactured by KMK. The contruction was dedicated to the passenger cruise vessel "North Star" The Strain Gauge measurement in different location and load situation was done in order to validate calculation finite element models used during strength analysis for project. The expertise contains: methodology of the measurements, description...
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Transmitting Alarm Information in DAB+ Broadcasting System
PublikacjaThe main goal of digital broadcasting is to deliver high-quality content with the lowest possible bitrate. This paper is focused on transmitting alarm information, such as emergency warning and alerting, in the DAB+ (Digital Audio Broadcasting plus) broadcasting system. These additional services should be available at the lowest possible bitrate, in order to provide a clear and understandable voice message to people. Furthermore, additional...
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Reliability estimation of underground horizontal fuel tank limit states
PublikacjaFuel tanks are designed with regard to standard loads and operating conditions. The investigations of the paper show the impact of such factors as tank corrosion and other means on the variation of stress fields and deformation of the underground horizontal tank shell. The introduction of probabilistic methods allows for structural reliability assessment. While the computational time of the entire tank FEM model is high, the preliminary...
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Transcriptome profiling reveals distinctive traits of retinol metabolism and neonatal parallels in the MRL/MpJ mouse
PublikacjaBackground: The MRL/MpJ mouse is a laboratory inbred strain known for regenerative abilities which are manifested by scarless closure of ear pinna punch holes. Enhanced healing responses have been reported in other organs. A remarkable feature of the strain is that the adult MRL/MpJ mouse retains several embryonic biochemical characteristics, including increased expression of stem cell markers. Results: We explored the transcriptome...
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Column base fixity in steel moment frames: Observations from instrumented buildings
PublikacjaThe rotational fixity of column base connections in Steel Moment Resisting Frames (SMRFs) strongly influences their seismic response. However, approaches for estimating base fixity have been validated only against laboratory test data. These approaches are examined based on strong motion recordings from four instrumented SMRF buildings in California to informbest practices for seismic response simulation. These buildings represent...
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Direct electrical stimulation of the human brain has inverse effects on the theta and gamma neural activities
PublikacjaObjective: Our goal was to analyze the electrophysiological response to direct electrical stimulation (DES) systematically applied at a wide range of parameters and anatomical sites, with particular focus on neural activities associated with memory and cognition. Methods: We used a large set of intracranial EEG (iEEG) recordings with DES from 45 subjects with electrodes...
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Novel approach to interference analysis of glucose sensing materials coated with Nafion
PublikacjaA gold-based sensing platform, TiND | AuNP | Nafion, was prepared as an exemplary electrode material exhibiting a response to glucose in a neutral solution. The change of electrochemical properties after exposure to glucose and interference compounds such as vitamin C, glycine, urea, paracetamol and acetylsalicylic acid was tested.
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Multi-objective design of miniaturized impedance transformers by domain segmentation
PublikacjaFast multi-objective design optimization of compact microstrip impedance transformers is discussed. Our approach exploits approximation models constructed using sampled coarse- mesh EM simulation data in a partitioned design space and response correction techniques for design refinement. Demonstra
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The sensitiveness of the speed of pile displacement to speed variations of hammer in beating down process
PublikacjaIn this paper there is presented dynamical system described speed of pile displacement during beating down process. Its response is determined by using Heaviside operator. There is introduced the convergence with regulator in partially ordered space. There is given an answer to the question, whetdisplacement is sensitive to hammer's speed variations.
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(R,R)-1-Acetyl-1'-(2,4,6-trinitrophenyl)-2,2'-bipyrrolidine
Publikacja(R,R)-1-Acetyl-1'-(2,4,6-trinitrophenyl)-2,2'-bipyrrolidine has been synthesized and its rentgenostructure has been determined. The structure of the title molecule, C16H19N5O7, is mainly determined by the steric effect of a bulky 2,4,6-trinitrophenyl group attached to the N atom of a pyrrolidine ring. Both pyrrolidine rings adopt an envelope conformation, with one of the methylene C atoms as the flap in each case, and the N-C-C-N...
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Post processing and selecting data obtain with parametric sub-bottom profiler SES-2000 Standard during sounding the Gulf of Gdansk
PublikacjaThe main goal of the paper is to describe the results of sounding the Gulf of Gdansk seabed using a parametric sub-bottom profiler SES-2000 Standard. Quality of obtained during trials data depends inter alia on proper location of antenna to reduce influence of pitch, roll, heave and ship noise (bubbles from propeller and a hull flow, vibration from main engine and peripheral devices). Furthermore calibration of complementary units...
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A new factor LapD is required for the regulation of LpxC amounts and lipopolysaccharide trafficking
PublikacjaLipopolysaccharide (LPS) constitutes the major component of the outer membrane and is essential for bacteria, such as Escherichia coli. Recent work has revealed the essential roles of LapB and LapC proteins in regulating LPS amounts; although, if any additional partners are involved is unknown. Examination of proteins co-purifying with LapB identified LapD as a new partner. The purification of LapD reveals that it forms a complex...
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Laminated plates and shells - first ply failure analysis within 6-parameter shell theory
PublikacjaThis 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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Crowdsourcing and Volunteer Computing as Distributed Approach for Problem Solving
PublikacjaIn this paper, a combination between volunteer computing and crowdsourcing is presented. Two paradigms of the web computing are described, analyzed and compared in detail: grid computing and volunteer computing. Characteristics of BOINC and its contribution to global Internet processing are shown with the stress put onto applications the system can facilitate and problems it can solve. An alternative instance of a grid computing...
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Numerical analysis of the carpentry joints applied in the traditional wooden structures
PublikacjaThe paper concerns the numerical analysis of the carpentry joints made from spruce wood. The material parameters of the wood have been calculated on the basis of nine independent material constants (an orthotropic material). The contact zone between the individual elements of the connection has been determined using Contact Tables in the MSC.Marc software. Five types of carpentry joints have been analyzed. The main aim of the research...
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Young’s modulus distribution in the FEM models of bone tissue
PublikacjaThis paper presents how differences of Young’s modulus in adjacent finite elements typical for organic materials such as bone tissue, influence stress calculating. Emphasizing high computational cost of variable Young’s modulus in parts of the model, where the number of finite elements has been raised, the authors wants to prove that new model of finite element which has variable Young’s modulus in its volume needs to be created....
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Quadratic Cohen representations in spectral analysis of serration process in Al–Mg alloys
PublikacjaImportant from mechanical point of view the Portevin–Le Chatelier serration phenomenon is being characterized by a complicated spectral profile. As a typical example of nonstationary processes it demands a special treatment allowing to follow the evolution of energy of stress fluctuations as a function of strain. The authors suggest the utilization of a compact system of quadratic transformations, known as Cohen class, as a technique...
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Local buckling and initial post-buckling behaviour of channel member flange - analytical approach
PublikacjaThe local buckling and initial post-buckling behaviour of the cold-formed channel member flange is investigated. The governing nonlinear differential equation for axially compressed columns and beams undergoing pure bending is derived using the stationary total potential energy principle. The critical stress and initial post-buckling equilibrium path is determined by means of a perturbation approach. The results obtained allow...
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An unorthodox view on the problem of tracking facial expressions
PublikacjaRecent developments in imaging cameras has opened a new way of analyzing facial expression. We would like to take advantage from this new technology and present a method of imaging and processing images of human face as a response to the particular stimuli. The response in this case is represented by the facial expressions and the stimuli are still images representing six basic emotions according to Eckmann. Working hypothesis...
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Chromogenic amides of pyridine-2,6-dicarboxylic acid as anion receptors
PublikacjaThe synthesis of simple, chromogenic pyridine-2,6-dicarboxylic acid amides, derivates of isomeric nitroanilines and aminonitrophenols, and their ion binding properties are described. The ligands' response to ionic species was examined by naked eye and was studied with the use of UV-Vis spectroscopy in DMSO and its mixture with water. The effect of the localisation and the type of the substituents in aromatic rings were discussed....
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Impact of surface skin temperature change on blood flow characteristics in palm
PublikacjaHeating a human palm during 3 minutes period causes changes in superficial skin temperature and leads to thermoregulation system response. The response time and level of flow characteristics change depend on the subject hand size and health of his vascular tree. A solution of Pennes bioheat propagation model was analyzed in order to see how much heat has to be transferred into the tissue to extort the observable reaction. The reflective...
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An unorthodox view on the problem of tracking facial expressions
PublikacjaRecent developments in imaging cameras has opened a new way of analyzing facial expression. We would like to take advantage from this new technology and present a method of imaging and processing images of human face as a response to the particular stimuli. The response in this case is represented by the facial expressions and the stimuli are still images representing six basic emotions according to Eckmann. Working hypothesis...
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SPECTRAL DYNAMIC ANALYSIS OF A STATIONARY JACK-UP PLATFORM
PublikacjaThe paper refers to the dynamic short-term response analysis of the Baltic steel drilling platform (see Fig.2) in a random sea-state represented by one-dimensional wave spectrum proposed by Striekalov and Massel and it is recommended for the Baltic Sea area. The Baltic drilling platform is a jack-up type platform for the exploration and exploitation of oil under the Baltic Sea. The analysis presented deals with the stationary...
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Graphene oxide, reduced graphene oxide and composite thin films NO2 sensing properties
PublikacjaA graphene oxide (GO), reduced graphene oxide (RGO) and poly(3,4-ethylenedioxytiophene)-reduced graphene oxide (PEDOT-RGO composite) gas sensors were successfully fabricated using an electrodeposition method. The electrodeposition was carried out in aqueous GO dispersions. To obtain RGO and PEDOT-RGO, the electrochemical reduction of GO and PEDOT-GO was carried out in 0.1 M KCl at a constant potential of −0.85 V. The GO, RGO and PEDOT-RGO...
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Effects of deviations from thermo-rheologically simple behavior of asphalt mixes in creep on developing of master curves of their stiffness modulus
PublikacjaThe paper presents the deviations from the thermo-rheologically simple behavior of asphalt mixes and their effects on the developing of master curves of stiffness modulus. Eleven different mixes were tested in three point bending test under constant load at temperatures –20°C, –10 °C and 0 °C, and in some cases at +10 °C. The test method was developed at the Gdansk University of Technology, Poland. The applied stress level was...
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Endothelial dysfunction due to eNOS uncoupling: molecular mechanisms as potential therapeutic targets
PublikacjaNitric oxide (NO) is one of the most important molecules released by endothelial cells, and its antiatherogenic properties support cardiovascular homeostasis. Diminished NO bioavailability is a common hallmark of endothelial dysfunction underlying the patho‑ genesis of the cardiovascular disease. Vascular NO is synthesized by endothelial nitric oxide synthase (eNOS) from the substrate L‑arginine (L‑Arg), with tetrahydrobiopterin...
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Influence of Bitumen Type and Asphalt Mixture Composition on Low-Temperature Strength Properties According to Various Test Methods
PublikacjaIn regions with low-temperatures, action transverse cracks can appear in asphalt pavements as a result of thermal stresses that exceed the fracture strength of materials used in asphalt layers. To better understand thermal cracking phenomenon, strength properties of different asphalt mixtures were investigated. Four test methods were used to assess the influence of bitumen type and mixture composition on tensile strength properties...
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Deposition and Electrical and Structural Properties of La0.6Sr0.4CoO3 Thin Films for Application in High-Temperature Electrochemical Cells
PublikacjaLow-temperature deposition of electroceramic thin films allows the construction of new devices and their integration with existing large-scale fabrication methods. Developing a suitable low-cost deposition method is important to further advance the development of microdevices. In this work, we deposited a 1-lm-thick La0.6Sr0.4CoO3d (LSC) perovskite with high electrical conductivity on sapphire substrates at 400C and analyzed its...
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Cost-efficient multi-objective design optimization of antennas in highly-dimensional parameter spaces
PublikacjaMulti-objective optimization of antenna structures in highly-dimensional parameter spaces is investigated. For expedited design, variable-fidelity EM simulations and domain patching algorithm are utilized. The results obtained for a monopole antenna with 13 geometry parameters are compared with surrogate-assisted optimization involving response surface approximation modeling.
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Adaptive Algorithm for Interactive Question-based Search
PublikacjaPopular web search engines tend to improve the relevanceof their result pages, but the search is still keyword-oriented and far from "understanding" the queries' meaning. In the article we propose an interactive question-based search algorithm that might come up helpful for identifying users' intents. We describe the algorithm implemented in a form of a questions game. The stress is put mainly on the most critical aspect of this...