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Search results for: X-RAY WAVE
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Excitation of Non-Wave Modes by Sound of Arbitrary Frequency in a Chemically Reacting Gas
PublicationThe nonlinear phenomena in the field of high intensity sound propagating in a gas with a chemical reaction, are considered. A chemical reaction of A → B type is followed by dispersion and attenuation of sound which may be atypical during irreversible thermodynamic processes under some conditions. The first and second order derivatives of heat produced in the chemical reaction evaluated at the equilibrium temperature, density and...
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Investigating Fuel Injection Strategies to Enhance Ship Energy Efficiency in Wave Conditions
PublicationThe prediction of fuel consumption and resulting transportation costs is a crucial stage in ship design, particularly for conditions involving motion in waves. This study investigates the real-time fuel consumption of a container ship when sailing in waves. The overall ship performance is evaluated using a novel non-linear coupled hull-engine-propeller interaction model. A series of towing tank experiments for hull resistance in...
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Ocena wpływu dawki DME na wybrane wskaźniki procesu spalania w dwupaliwowym silniku o zapłonie samoczynnym
PublicationPrzedmiotem rozprawy jest analiza wpływu różnej ilości odparowanego DME wprowadzonego do kolektora dolotowego na wybrane wskaźniki spalania DME/ON dla wielu punktów pracy, turbodoładowanego silnika o zapłonie samoczynnym. Jako punkty pracy silnika, wybrano punkty najbardziej reprezentujące cykl jazdy WLTP dla samochodu Volkswagen Golf IV. Analizę procesu współspalania przeprowadzono z wykorzystaniem danych pomiarowych, uzyskanych...
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High temperature corrosion resistance of porous hastelloy alloy
PublicationTo further understand the suitability of Ni-Cr-base alloy for solid oxide fuel cell (SOFC), a commercial Ni-Cr-Fe-Mo alloy, Hastelloy X was selected and evaluated for oxidation behaviour under high temperature conditions. HastelloyX was chosen due to its unusual resistance to oxidizing, reducing and neutral atmospheres. For long term stability of metal supported fuel cell, the corrosion resistance plays a vital role and must be...
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Constrained multi-objective optimization of compact microwave circuits by design triangulation and pareto front interpolation
PublicationDevelopment of microwave components is an inherently multi-objective task. This is especially pertinent to the design closure stage, i.e., final adjustment of geometry and/or material parameters carried out to improve the electrical performance of the system. The design goals are often conflicting so that the improvement of one normally leads to a degradation of others. Compact microwave passives constitute a representative case:...
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Low-Cost Modeling of Microwave Components by Means of Two-Stage Inverse/Forward Surrogates and Domain Confinement
PublicationFull-wave electromagnetic (EM) analysis is one of the most important tools in the design of modern microwave components and systems. EM simulation permits reliable evaluation of circuits at the presence of cross-coupling effects or substrate anisotropy, as well as for accounting for interactions with the immediate environment. However, repetitive analyses required by EM-driven procedures, such as parametric optimization or statistical...
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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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Series-Slot-Fed Circularly Polarized Multiple-Input-Multiple-Output Antenna Array Enabling Circular Polarization Diversity for 5G 28-GHz Indoor Applications
PublicationIn this paper, a four-element circularly polarized series-slot-fed multiple-input-multiple-output (MIMO) antenna array with circular polarization diversity is presented. The proposed design utilizes a combination of 45-degree inclined slots and a straight microstrip line feeding technique. The two antennas are designed to operate with the opposite sense of circular polarization (CP). CP is achieved by placing a patch of just about...
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Expedited Acquisition of Database Designs for Reduced-Cost Performance-Driven Modeling and Rapid Dimension Scaling of Antenna Structures
PublicationFast replacement models have been playing an increasing role in high-frequency electronics, including the design of antenna structures. Their role is to improve computational efficiency of the procedures that normally entail large numbers of expensive full-wave electromagnetic (EM) simulations, e.g., parametric optimization or uncertainty quantification. Recently introduced performance-driven modeling methods, such as the nested...
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On Fast Multi-objective Optimization of Antenna Structures Using Pareto Front Triangulation and Inverse Surrogates
PublicationDesign of contemporary antenna systems is a challenging endeavor, where conceptual developments and initial parametric studies, interleaved with topology evolution, are followed by a meticulous adjustment of the structure dimensions. The latter is necessary to boost the antenna performance as much as possible, and often requires handling several and often conflicting objectives, pertinent to both electrical and field properties...
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Low-Cost and Highly-Accurate Behavioral Modeling of Antenna Structures by Means of Knowledge-Based Domain-Constrained Deep Learning Surrogates
PublicationThe awareness and practical benefits of behavioral modeling methods have been steadily growing in the antenna engineering community over the last decade or so. Undoubtedly, the most important advantage thereof is a possibility of a dramatic reduction of computational expenses associated with computer-aided design procedures, especially those relying on full-wave electromagnetic (EM) simulations. In particular, the employment of...
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Low-Cost Yield-Driven Design of Antenna Structures Using Response-Variability Essential Directions and Parameter Space Reduction
PublicationQuantifying the effects of fabrication tolerances and uncertainties of other types is fundamental to improve antenna design immunity to limited accuracy of manufacturing procedures and technological spread of material parameters. This is of paramount importance especially for antenna design in the industrial context. Degradation of electrical and field properties due to geometry parameter deviations often manifests itself as, e.g.,...
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Chitosan-based inks for 3D printing and bioprinting
PublicationThe advent of 3D-printing/additive manufacturing in biomedical engineering field has introduced great potential for the preparation of 3D structures that can mimic native tissues. This technology has accelerated the progress in numerous areas of regenerative medicine, especially led to a big wave of biomimetic functional scaffold developments for tissue engineering demands. In recent years, the introduction of smart bio-inks has...
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Rapid Antenna Optimization with Restricted Sensitivity Updates by Automated Dominant Direction Identification
PublicationMeticulous tuning of geometry parameters turns pivotal in improving performance of antenna systems. It is more and more often realized using formal optimization methods, which is demonstrably the most efficient way of handling multiple design variables, objectives, and constraints. Although in some cases a need for launching global search arises, a typical design scenario only requires local optimization, especially when a decent...
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Nested Kriging with Variable Domain Thickness for Rapid Surrogate Modeling and Design Optimization of Antennas
PublicationDesign of modern antennas faces numerous difficulties, partially rooted in stringent specifications imposed on both electrical and field characteristics, demands concerning various functionalities (circular polarization, pattern diversity, band-notch operation), but also constraints imposed upon the physical size of the radiators. Conducting the design process at the level of full-wave electromagnetic (EM) simulations, otherwise...
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Design-oriented modeling of antenna structures by means of two-level kriging with explicit dimensionality reduction
PublicationThe employment of full-wave electromagnetic (EM) analysis is a practical necessity in the design of contemporary antenna structures. This is because simpler models are generally not available or of limited accuracy. At the same time, EM-based design is computationally expensive. Consequently, the ways of accelerating tasks such as parametric optimization or uncertainty quantification have to be sought. A possible workaround that...
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Improved Modeling of Microwave Structures Using Performance-Driven Fully-Connected Regression Surrogate
PublicationFast replacement models (or surrogates) have been widely applied in the recent years to accelerate simulation-driven design procedures in microwave engineering. The fundamental reason is a considerable—and often prohibitive—CPU cost of massive full-wave electromagnetic (EM) analyses related to solving common tasks such as parametric optimization or uncertainty quantification. The most popular class of surrogates are data-driven...
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Variable Data Structures and Customized Deep Learning Surrogates for Computationally Efficient and Reliable Characterization of Buried Objects
PublicationIn this study, in order to characterize the buried object via deep-learning-based surrogate modeling approach, 3-D full-wave electromagnetic simulations of a GPR model has been used. The task is to predict simultaneously and independent of each characteristic parameters of a buried object of several radii at different positions (depth and lateral position) in various dispersive subsurface media. This study has analyzed variable...
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Design-Oriented Two-Stage Surrogate Modeling of Miniaturized Microstrip Circuits with Dimensionality Reduction
PublicationContemporary microwave design heavily relies on full-wave electromagnetic (EM) simulation tools. This is especially the case for miniaturized devices where EM cross-coupling effects cannot be adequately accounted for using equivalent network models. Unfortunately, EM analysis incurs considerable computational expenses, which becomes a bottleneck whenever multiple evaluations are required. Common simulation-based design tasks include...
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On Computationally-Efficient Reference Design Acquisition for Reduced-Cost Constrained Modeling and Re-Design of Compact Microwave Passives
PublicationFull-wave electromagnetic (EM) analysis has been playing a major role in the design of microwave components for the last few decades. In particular, EM tools allow for accurate evaluation of electrical performance of miniaturized structures where strong cross-coupling effects cannot be adequately quantified using equivalent network models. However, EM-based design procedures (parametric optimization, statistical analysis) generate...
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Panel obywatelski z perspektywy obserwatora – przypadek Warszawskiego Panelu Klimatycznego - Citizen Assembly from observer perspective – case of Warsaw Climate Assembly
PublicationPanele obywatelskie są coraz częściej stosowanym w polskich miastach instrumentem demokratycznym. Przykładem tej deliberacyjnej fali był Warszawski Panel Obywatelski, który odbył się jesienią 2020 r. Autor artykułu pełnił rolę obserwatora przy WPK i miał okazję zapoznać się dokładnie z przebiegiem panelu i jego pracami. Praca obejmuje ana-lizę pięciu kluczowych aspektów dla funkcjonowania panelu obywatelskiego, tzn. dobór tematu,...
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Evidence for consolidation of neuronal assemblies after seizures in humans
PublicationThe establishment of memories involves reactivation of waking neuronal activity patterns and strengthening of associated neural circuits during slow-wave sleep (SWS), a process known as "cellular consolidation" (Dudai and Morris, 2013). Reactivation of neural activity patterns during waking behaviors that occurs on a timescale of seconds to minutes is thought to constitute memory recall (O'Keefe and Nadel, 1978), whereas consolidation...
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Computationally Efficient Design Optimization of Compact Microwave and Antenna Structures
PublicationMiniaturization is one of the important concerns of contemporary wireless communication systems, especially regarding their passive microwave components, such as filters, couplers, power dividers, etc., as well as antennas. It is also very challenging, because adequate performance evaluation of such components requires full-wave electromagnetic (EM) simulation, which is computationally expensive. Although high-fidelity EM analysis...
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Charge Distribution and Hyperfine Interactions in GdBa2Cu3O7 from First Principles
PublicationW rozdziale przedstawiono wyniki obliczeń "z zasad pierwszych" (''ab initio'') struktury elektronowej, rozkładu ładunku i struktury nadsubtelnej, w szczególności gradientu pola elektrycznego (EFG) i składnika kontaktowego pola nadsubtelnego (HFF), nadprzewodnika wysokotemperaturowego o wzorze GdBa2Cu3O7 (Gd123). Do obliczeń wykorzystano metodę FP-LAPW (full-potential linearized augmented plane wave). Efekty związane z oddziaływaniami...
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MATHEMATICAL MODELING OF FLOOD MANAGEMENT SYSTEM IN THE CITY OF GDAŃSK, ORUŃSKI STREAM CASE STUDY
PublicationAim of the study This study analyses the efficiency of flood protection in a small urban catchment, based on a system of small reservoirs. Material and methods To assess the flood routing and surge reduction, a mathematical model of the river catchment was implemented. This was a lumped hydrological model, based on the SCS-CN method. Channel routing was performed, using kinematic wave equation. The sub-catchments have been determined...
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Implementation of spatial/polarization diversity for improved-performance circularly polarized multiple-input-multiple-output ultra-wideband antenna
PublicationIn this paper, spatial and polarization diversities are simultaneously implemented in an ultra-wideband (UWB) multiple-input-multiple-output (MIMO) antenna to reduce the correlation between the parallel-placed radiators. The keystone of the antenna is systematically modified coplanar ground planes that enable excitation of circular polarization (CP). To realize one sense of circular polarization as well as ultra-wideband operation,...
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Accelerated Parameter Tuning of Antenna Structures by Means of Response Features and Principal Directions
PublicationPopularity of numerical optimization has been steadily on the rise in the design of modern antenna systems. Resorting to mathematically rigorous parameter tuning methods is a matter of practical necessity as interactive techniques (e.g., parameter sweeping) are no longer adequate when handling several performance figures over multi-dimensional parameter spaces. The most common design scenarios involve local tuning since decent...
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Expedited Metaheuristic-Based Antenna Optimization Using EM Model Resolution Management
PublicationDesign of modern antenna systems heavily relies on numerical opti-mization methods. Their primary purpose is performance improvement by tun-ing of geometry and material parameters of the antenna under study. For relia-bility, the process has to be conducted using full-wave electromagnetic (EM) simulation models, which are associated with sizable computational expendi-tures. The problem is aggravated in the case of global optimization,...
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Globalized Parametric Optimization of Microwave Passive Components Using Simplex-Based Surrogates
PublicationOptimization-based parameter adjustment involving full-wave electromagnetic (EM) simulation models is a crucial stage of present-day microwave design process. In fact, rigorous optimization is the only reliable mean permitting to simultaneously handle multiple geometry/material parameters, objectives, and constraints. Unfortunately, EM-driven design is a computationally intensive endeavor. While local tuning is usually manageable,...
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Fast Re-Design of Multi-Band Antennas by Means of Orthogonal-Direction Geometry Scaling and Local Parameter Tuning
PublicationApplication-driven design of antenna systems fosters a reuse of structures that have proven competitive in terms of their electrical and field performance, yet have to be re-designed for a new application area. In practice, it most often entails relocation of the operating frequencies or bandwidths, which is an intricate endeavor, normally requiring utilization of numerical optimization techniques. If the center frequencies of...
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Machine-Learning-Based Global Optimization of Microwave Passives with Variable-Fidelity EM Models and Response Features
PublicationMaximizing microwave passive component performance demands precise parameter tuning, particularly as modern circuits grow increasingly intricate. Yet, achieving this often requires a comprehensive approach due to their complex geometries and miniaturized structures. However, the computational burden of optimizing these components via full-wave electromagnetic (EM) simulations is substantial. EM analysis remains crucial for circuit...
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Global Design Optimization of Microwave Circuits Using Response Feature Inverse Surrogates
PublicationModern microwave design has become heavily reliant on full-wave electromagnetic (EM) simulation tools, which are necessary for accurate evaluation of microwave components. Consequently, it is also indispensable for their development, especially the adjustment of geometry parameters, oriented towards performance improvement. However, EM-driven optimization procedures incur considerable computational expenses, which may become impractical...
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PROJEKT I KONSTRUKCJA ŁOŻYSKA "X" O ZWIĘKSZONEJ ZDOLNOŚCI DO TŁUMIENIA DRGAŃ (łożysko nr 2 turbiny TK-78 w El. Jaworzno II)
PublicationProjekt łożyska X2 dla turbiny 13CK70 został wykonany w oparciu o analizę właściwości różnych wariantów geometrii. Porównanie właściwości łożysk cytrynowych z łożyskiem X wykazało uzyskanie wyraźnej poprawy własności dynamicznych nowego łożyska, a szczególnie jego sztywności, zdolności do tłumienia drgań oraz odporności na zmianę kierunku działania obciążenia. W wyniku przeprowadzonego wdrożenie uzyskano znakomitą poprawę stanu...
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A Comparison between MD and EXAFS extracted Structural Data for TernaryRbBr(1-x)Ix.
PublicationStrukturę trójskładnikowych soli poddano analizie za pomocą metody EXAFS i symulacji M-D. Przedyskutowano przydatność używanego w symulacjach potencjału oddziaływań międzyatomowych.
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An ab initio study on MgX3− and CaX3− superhalogen anions (X=F, Cl, Br)
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BX4− and AlX4− Superhalogen Anions (X = F, Cl, Br): An ab Initio Study
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Koncepcja usprawnienia procesu spawania sekcji przestrzennych jednostek wielogabarytowych w stoczni X.
PublicationCelem artykułu jest przedstawienie koncepcji usprawnienia procesu spawania sekcji przestrzennych w kadłubie statku. Przedmiotem analizy projektu będzie styk międzyblokowy, który pospawany zostanie dwoma różnymi metodami. W artykule przedstawione zostaną rozwiązania techniczne wspomagające procesy spawalnicze oraz pomiary i obliczenia umożliwiające porównanie obu metod spawania.
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Accuracy Analysis of Measuring X-Y-Z Coordinates with Regard to the Investigation of the Tombolo Effect
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Effect of sintering temperature on electrochemical performance of porous SrTi1-xFexO3-δ (x = 0.35, 0.5, 0.7) oxygen electrodes for solid oxide cells
PublicationThis work evaluates the effects of the sintering temperature (800 °C, 900 °C, 1000 °C) of SrTi1-xFexO3-δ (x = 0.35, 0.5, 0.7) porous electrodes on their electrochemical performance as potential oxygen electrode materials of solid oxide cells. The materials were prepared by a solid-state reaction method and revealed the expected cubic perovskite structure. After milling, the powders were characterised by a sub-micrometre particle...
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/sup 6/LiI(Eu) in neutron and /spl gamma/-ray spectrometry-a highly sensitive thermal neutron detector
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Performance of CMS hadron calorimeter timing and synchronization using test beam, cosmic ray, and LHC beam data
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Luminescent, Scintillation, and Photoconversion Properties of Micro‐Pulling‐Down‐Grown Single Crystals of Ce 3+ ‐Doped Gd 3− x Lu x Al 5− y Ga y O 12 Garnets
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Full scale CFD seakeeping simulations for case study ship redesigned from V-shaped bulbous bow to X-bow hull form
PublicationIncreasing propulsion efficiency, safety, comfort and operability are of the great importance, especially for small ships operating on windy sites like the North Sea and the Baltic Sea. Seakeeping performance of ships and offshore structures can be analysed by different methods and the one that is becoming increasingly important is CFD RANS. The recent development of simulation techniques together with rising HPC accessibility...
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Nuclear Magnetic Relaxation and d-Wave Pairing in a Model of a Superconductor with Non-Retarded Attraction
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Nuclear magnetic relaxation and d-wave pairing in an extended Hubbard model with diagonal disorder
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Monitoring the curing process of epoxy adhesive using ultrasound and Lamb wave dispersion curves
PublicationMonitoring the stiffness of adhesives is a crucial issue when considering the durability andstrength of adhesive joints. While there are many studies conducted on specimens madeonly from adhesive, the problem of curing of an adhesive film in real joints is moderatelyconsidered. This paper presents the monitoring of stiffening of epoxy adhesive using ultra-sound. Ultrasonic pulse velocity method was firstly applied for monitoring...
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Analysis of electromagnetic plane wave scattering from 2-d periodic arrangements of posts
PublicationArtykuł prezentuje metodę analizy rozpraszania fali elektromagnetycznej od układu periodycznie rozłożonych obiektów cylindrycznych na płaszczyźnie. Opisywane podejście analizy wykorzystuje pełnofalowe rozwiązanie oparte na metodzie dopasowania rodzajów. Wynikiem analizy jest wielorodzajowa macierz rozproszenia badanych powierzchni periodycznych.
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Modelling of wave propagation in composite plates using the time domain spectral element method
PublicationW pracy przedstawiono wyniki obliczeń propagacji fali sprężystej w płycie kompozytowej modelowanej z wykorzystaniem czasowego sformułowania metody elementów spektralnych
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Piecewise continuous distribution function method: Fluid equations and wave disturbances at stratified gas
PublicationUkład równań typu hydrodynamicznego dla warstwowych gazów w polu grawitacyjnym pochodzi od równania BGK metodą częściowej ciągłej funkcji dystrybucji. Otrzymany system równań uogólnia układ Naviera-Stokesa w dowolnych liczbach Knudsena. Rozwiązania WBK dla ultradźwięku wprowadza się w przypadku stratyfikacji exponecjalnej.
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MicroscopicA75sNMR study of the effect of impurities on the first-order spin-density-wave transition inBaFe2As2
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