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Previous approaches to modelling interval-censored data have often relied on assumptions of homogeneity in the sense that the censoring mechanism, the underlying distribution of occurrence times, or both, are assumed to be time-invariant. In this work, we introduce a model which allows for non-homogeneous behaviour in both cases. In particular, we outline a censoring mechanism based on semi-Markov processes in which interval generation is assumed to be time-dependent and we propose a Markov point process model for the underlying occurrence time distribution. We prove the existence of this process and derive the conditional distribution of the occurrence times given the intervals. We provide a framework within which the process can be accurately modelled, and subsequently compare our model to homogeneous approaches by way of a parametric example.

The authors of this study gratefully acknowledge Prof. C. Larchet and Prof. V. Nikonenko for donating MK40 membrane samples, and ICTS Centro Nacional de Microscopia UCM for AFM image. Financial support from Universidad Complutense of Madrid under Project PR1/08-15918-A is also gratefully acknowledged., Water uptakes properties and effective fixed charge concentration have been determined in aqueous electrolyte solutions (LiCl, NaCl and KCl) for different commercial sulfonated polymer cation-exchange membranes with different morphology. Differences in the water uptake properties and in the membrane effective fixed charge concentration has been found, which have been analyzed on the basis of the different membrane structures. The experimental results show correlations between the water uptake and the loss of the membrane selectivity at high electrolyte concentrations which are dependent on the membrane morphology. Relationships are found which permit to estimate the membrane effective fixed charge concentration from equilibrium and morphological properties with the advantage of avoiding the need for membrane potential measurements., Universidad Complutense of Madrid, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

In a premixed dual-fuel (DF) methane-diesel engine, the ignition of the lean premixed methane/air mixture starts with the assistance of a pilot diesel injection. Auto-ignition of pilot fuel is important as it triggers the subsequent combustion processes. A delay in the auto-ignition process may lead to misfiring, incomplete combustion, and thus higher greenhouse emissions due to methane slip. Hence, a better understanding of the auto-ignition process for the pilot fuel can help to improve the overall engine performance, combustion efficiency, and to lower exhaust emission levels. In the present study, large eddy simulation (LES) is used to investigate the auto-ignition process of micro-pilot diesel in premixed DF combustion in a constant volume combustion chamber (CVCC). The entire DF combustion processes including methane gas injection, methane/air mixing, pilot diesel injection, and ignition are simulated. The numerical model is validated against experimental data. The present numerical model is able to capture the ignition delay time (IDT) within a maximum relative difference of 7% to the measurements. A higher relative difference of 38% is obtained when methane gas injection and mixing are omitted in the simulation and the methane/air is assumed homogeneous. This demonstrates the importance of inhomogeneity pockets. To study the effects of temperature and methane inhomogeneities separately, different idealized inhomogeneities in temperature and methane distribution are considered inside the CVCC. The inhomogeneity in the temperature is observed to have a more profound influence on the IDT than the methane inhomogeneity. The inhomogeneity pockets of temperature advance the first-stage ignition and, subsequently, the second-stage ignition. A sensitivity analysis on the effect of inhomogeneity wavelength reveals that the larger wavelengths enhance the combustion due to the presence of pilot diesel jets in the desirable regions for a longer time duration.

Microbially induced carbonate precipitation (MICP) involves bacteria to drive calcite precipitation and naturally cement soils, thereby improving soils performance. Experimental studies have shown that bio-cemented specimen can suffer from severe spatial inhomogeneity of the calcite content, leading to large uncertainty in treatment efficiency prediction. To evaluate the effect of inhomogeneity on the mechanical behaviour of bio-cemented soils, the discrete element method (DEM) is used to model bio-cemented samples with a single carbonate distribution pattern (i.e. either bridging or contact cementing) but different characteristics of inhomogeneity. Both drained triaxial compression and triaxial extension simulations are carried out to evaluate the impact of inhomogeneity along different loading paths. The results indicate that inhomogeneity has different effects on bio-cemented samples depending on the carbonate distribution patterns and the loading path. Specifically, the shear strength in compression of samples exhibiting bridging cementation is largely affected by inhomogeneity, while the effect on shear strength in extension is negligible. On the other hand, samples with contact cementing show limited sensitivity to the variation of inhomogeneity under both triaxial compression and triaxial extension tests., Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Geo-engineering

Low field magnetic resonance imaging (MRI) scanners provide a unique low-cost alternative to conventional MRI scanners. Nevertheless, low-field scanners come with drawbacks such as reduced signal-to-noise ratio and resolution, and also distorted images caused by magnetic field inhomogeneity and non-linear gradient fields. Despite this, it still provides a more accessible way to provide MRI in resource-limited areas. The main goal of this thesis is to develop an algorithm that can reconstruct 3D data from the low-field scanner efficiently and without distortion to the image. To do this, conjugate phase reconstruction (CPR) is employed, particularly frequency segmented reconstruction (Noll, 1991) and multifrequency interpolation (Man et al., 1997)., Low-Field MRI, BioMedical Engineering

Low-field MRI is susceptible to temperature changes in magnet temperature, resulting in time-dependent inhomogeneities. This causes time-dependent phase shifts in the measured signal, leading to image distortions. In this project, a method is proposed to interleave short magnetic field (B0) mapping sequences in the target image acquisition for Turbo Spin Echo (TSE) and Magnetic Resonance Fingerprinting (MRF). Simulations show that the proposed correction method works in 2D. Experiment results show that interleaved B0 mapping can be done at relatively low spatial and temporal resolution, shortening the B0 acquisition time. Also, the distortion correction works for both TSE and MRF, though its advantages over static inhomogeneity correction are limited to acquisitions with a small bandwidth per voxel and large or very inhomogeneous frequency drifts., BioMedical Engineering | Medical Physics

In this work, we succeeded in direct visualization of the network structure of synthetic hydrogels with TEM by developing a novel staining and network fixation method. Such a direct visualization had not been carried out because sample preparation and obtaining sufficient contrast are challenging for these soft materials. TEM images revealed robust heterogeneous network architectures at mesh size scale and defects at micro-scale. TEM images also revealed the presence of abundant dangling chains on the surface of the hydrogel network. The real space structural information provides a comprehensive perspective that links bulk properties with a nanoscale network structure, including fracture, adhesion, sliding friction, and lubrication. The presented method has the potential to advance the field.

Low field magnetic resonance imaging (MRI) scanners provide a unique low-cost alternative to conventional MRI scanners. Nevertheless, low-field scanners come with drawbacks such as reduced signal-to-noise ratio and resolution, and also distorted images caused by magnetic field inhomogeneity and non-linear gradient fields. Despite this, it still provides a more accessible way to provide MRI in resource-limited areas. The main goal of this thesis is to develop an algorithm that can reconstruct 3D data from the low-field scanner efficiently and without distortion to the image. To do this, conjugate phase reconstruction (CPR) is employed, particularly frequency segmented reconstruction (Noll, 1991) and multifrequency interpolation (Man et al., 1997)., Low-Field MRI, Biomedical Engineering

Low-field MRI is susceptible to temperature changes in magnet temperature, resulting in time-dependent inhomogeneities. This causes time-dependent phase shifts in the measured signal, leading to image distortions. In this project, a method is proposed to interleave short magnetic field (B0) mapping sequences in the target image acquisition for Turbo Spin Echo (TSE) and Magnetic Resonance Fingerprinting (MRF). Simulations show that the proposed correction method works in 2D. Experiment results show that interleaved B0 mapping can be done at relatively low spatial and temporal resolution, shortening the B0 acquisition time. Also, the distortion correction works for both TSE and MRF, though its advantages over static inhomogeneity correction are limited to acquisitions with a small bandwidth per voxel and large or very inhomogeneous frequency drifts., Biomedical Engineering | Medical Physics

Precisely knowing the refractive index of a piece of glass can be a complicated and expensive task and knowing it over a large area gets even more difficult. We are proposing a method that can measure the inhomogeneity of the refractive index of an optic while utilizing a large area and is cost effective.. We are proposing the use of multiple deflectometry measurements that will calculate the difference between two surface maps where the only change is the introduction of small variations to the refractive index under test. This system is based on the geometry of fringe reflection deflectometry to measure the slope of an object rapidly and accurately. By placing a fluid on top of the usual mirror used in a deflectometry system, we can measure the slope of a mirror that is equivalent to this “liquid lens”. Then introduce a piece of glass with a refractive index similar to the fluid and measure again. Subtracting the two images allows for the calculation of the difference in the refractive index thus allowing us to see the inhomogeneity across the glass in question.

В дисертації запропоновано мікросмужкові фільтри нижніх частот на основі тривимірних електромагнітнокристалічних неоднорідностей (ЕКН). Виконано порівняння розрахункових амплітудно-частотних характеристик (АЧХ) квазізосереджених реактивних елементів на основі традиційних структур та ЕКН. АЧХ квазізосереджених реактивних елементів на основі ЕКН помітно ближчі до АЧХ зосереджених елементів. Гранична частота смуги подавлення, що визначається частотою першого мінімуму АЧХ, для ЕКН в три рази вища. Характеристики розраховано за допомогою програмного пакета тривимірного електромагнітного моделювання CST Microwave Studio. Запропоновано ЕКН, що поєднують індуктивний і ємнісний елементи. Такі ЕКН названо суміщеними. Представлено структури фільтрів нижніх частот на основі поодиноких і суміщених ЕКН. Наведено розрахункові та експериментальні параметри і АЧХ фільтрів, що ілюструють помітне зменшення розмірів і покращення АЧХ у смузі подавлення проти фільтра традиційної структури. Виконано порівняння результатів три- та одновимірного моделювання мікросмужкових фільтрів нижніх частот традиційних конструкцій та на основі тривимірних ЕКН. Одновимірна модель являє собою неоднорідну лінію передачі з еквівалентними параметрами. Розглянуто фільтри на основі різноімпедансних секцій мікросмужкової лінії та з ємнісним шлейфом. Обґрунтовано можливість використання одновимірної моделі як моделі першого наближення. Розглянуто конструктивні відмінності традиційного двовимірного та тривимірного ємнісних шлейфів та виконано порівняння їх ємностей. Запропоновано конструкцію для зменшення паразитного ємнісного зв’язку шлейфів.

In this article, a β-Ga₂O₃ metal-interlayer-semiconductor Schottky barrier diode (MIS-SBD) using Al-reacted aluminum oxide as the interlayer is demonstrated for the first time and compared with conventional metal-semiconductor (MS) Schottky barrier diode (SBD). The aluminum oxide is formed by sputtering a thin Al layer on Ga₂O₃ substrate and then annealed in O₂ at 300 °C. With the insertion of Al-reacted interlayer, the SBD subthreshold swing (SS) is significantly improved to 61 mV/dec with an average current range of >6 orders. Example of atomic layer deposited (ALD) Al₂O₃ as the interlayer is also fabricated and characterized. J-V study corrected by Gaussian distribution model shows that all the samples statistically exhibit similar mean barrier heights (BHs). This indicates that the interlayer hardly affects the electrostatic field and band bending as experienced by carrier injections. C-V study provides different BH results in different sample setups. The result proves that Al-reacted interfacial layer helps eliminate interface degradation as compared with ALD Al₂O₃. Overall, MIS-SBD by Al-reaction method exhibits improved SS, reduced reverse leakage current (I₀), low ideality factor, good on-off ratio (>10⁹), and minimized interface charges as compared with its respective counterparts. The result of this article serves as a promising interface engineering technique for Ga₂O₃-based SBD designs. IEEE

В дисертації запропоновано мікросмужкові фільтри нижніх частот на основі тривимірних електромагнітнокристалічних неоднорідностей (ЕКН). Виконано порівняння розрахункових амплітудно-частотних характеристик (АЧХ) квазізосереджених реактивних елементів на основі традиційних структур та ЕКН. АЧХ квазізосереджених реактивних елементів на основі ЕКН помітно ближчі до АЧХ зосереджених елементів. Гранична частота смуги подавлення, що визначається частотою першого мінімуму АЧХ, для ЕКН в три рази вища. Характеристики розраховано за допомогою програмного пакета тривимірного електромагнітного моделювання CST Microwave Studio. Запропоновано ЕКН, що поєднують індуктивний і ємнісний елементи. Такі ЕКН названо суміщеними. Представлено структури фільтрів нижніх частот на основі поодиноких і суміщених ЕКН. Наведено розрахункові та експериментальні параметри і АЧХ фільтрів, що ілюструють помітне зменшення розмірів і покращення АЧХ у смузі подавлення проти фільтра традиційної структури. Виконано порівняння результатів три- та одновимірного моделювання мікросмужкових фільтрів нижніх частот традиційних конструкцій та на основі тривимірних ЕКН. Одновимірна модель являє собою неоднорідну лінію передачі з еквівалентними параметрами. Розглянуто фільтри на основі різноімпедансних секцій мікросмужкової лінії та з ємнісним шлейфом. Обґрунтовано можливість використання одновимірної моделі як моделі першого наближення. Розглянуто конструктивні відмінності традиційного двовимірного та тривимірного ємнісних шлейфів та виконано порівняння їх ємностей. Запропоновано конструкцію для зменшення паразитного ємнісного зв’язку шлейфів., The thesis proposed microstrip low-pass filters based on three-dimensional (3D) electromagnetic-crystal inhomogeneities (ECI). Recently, there has been a rapid development of electronic systems for various purposes, including telecommunications. Modern technologies require constant increase of selectivity and reduction the mass and dimensional parameters of devices. Modern electronic and telecommunication means actively use passive microstrip filters for signal processing. One of the directions of development of microstrip filters is the use of electromag netic crystals and ECI. The implementation of quasi-concentrated reactive elements based on 3D ECІ with a significant increase in the values of reactivity’s in comparison with traditional mi crostrip structures is proposed. A comparison of ECI characteristics and traditional struc tures is performed. Constructions of combined ECI inhomogeneities are proposed. As a model of the first approximation for combined ECIs, a one-dimensional model is considered, which allowed to obtain analytical results. A comparison of the efficiency of single and com bined ECIs with the help of one-dimensional and three-dimensional models is performed. The experimental and calculated characteristics of the EC based on single and combined inhomogeneities are given. The quasi-lumped capacitor is also used as an open stub connected to the main line. Traditional designs of such stubs are two-dimensional (2D) in the form of segments of a microstrip line. The use of a capacitive stub based on ECI is proposed. The structural differences of 2D and 3D capacitive stubs are considered. The 3D stub has significantly better parameters compared to the 2D loop: its wave impedance is 1.4… 3.5 times small er, and the capacity is 1.6… 4.1 times larger. Because the filter requires specified capacitance values, the area of the 3D stub is correspondingly smaller. 3D modeling analyzes the features of the dependences of the electrical parameters of the 3D-stub

Using a conventional bi-planar turbulence-generating grid, we confirm the recent findings (Valente & Vassilicos, Phys. Rev. Lett., vol. 108, 2012, art. 214503) that show there is a turbulence decay region close to the generating grid that departs from the 'classical' turbulence decay (Comte-Bellot & Corrsin, J. Fluid Mech., vol. 25, 1966, pp. 657-682). In this 'near-field' region, the turbulence energy decays more rapidly than in the far-field and it exhibits unusual scaling properties. Based on the velocity decay laws, we show that for our conventional grid, the near-field extends from x/M ~ 6 to x/M ~ 12 where x is the downstream distance from the grid and M is the mesh size. This corresponds to 1.1 = x/x* = 2.3 where x* is the wake interaction length scale (Mazellier & Vassilicos, Phys. Fluids, vol. 22, 2010, art. 075101). However, other statistics (velocity derivatives and length-scale ratios) indicate that the extent of the initial period depends on the grid mesh Reynolds number, RM, extending further for higher values of RM. In the near-field the turbulence approaches isotropy both at the large and small scales but there still is inhomogeneity in the derivative statistics. The derivative skewness also departs from values observed at comparable Reynolds numbers in the far-field decay region, and in other turbulent flows at comparable Reynolds numbers. Two values of RM were studied: 42 × 103 and 76 × 103. © 2014 Cambridge University Press.

Статья посвящена исследованию напряженно-деформированного состояния непрерывно-неоднородных тел с использованием метода граничных интегральных уравнений. С помощью метода возмущений трехмерная краевая задача термоупругости изотропных непрерывно-неоднородных тел сводится к последовательности краевых задач термоупругости и теории упругости однородных тел. Построены сингулярные интегральные уравнения трехмерной краевой задачи термоупругости при переменном коэффициенте a(T) .

We present an evolution-strategy based approach to solve the magnitude least squares (MLS) design problem of low flip-angle slice-selective parallel transmit RF pulses for ultra-high field MRI using SAR and peak-RF-constraints. A combined transmit k-space trajectory and RF pulse weight optimization is proposed in two algorithmic steps. The first step is a coarse grid search to find an initial solution that fulfills all constraints for the subsequent multistage optimization. This avoids convergence to the next nearest local minimum. The second step attempts to refine the results using multiple evolution strategies. We compare the performance of our approach with the non-convex optimization methods described in the literature. The proposed algorithm converges for phantom and in vivo data and only requires an initial estimate of the range of suitable regularization parameters. It demonstrates improved excitation homogeneity compared to published spoke-design methods and allows optimization for homogeneity with a subsequent reduction in the SAR burden. Moreover, excitation homogeneity and the SAR burden can be balanced against each other, enabling a further reduction in SAR at the cost of minor relaxations in excitation homogeneity. This feature makes the algorithm a good candidate for SAR limited sequences in ultra-high field imaging. The algorithm is validated using phantom and in vivo measurements obtained with a 16-channel transmit array at 9.4 T.

Ferritic-martensitic ODS steels are one of the candidate materials for Gen-IV nuclear fission and fusion reactors. Residual ferrite was often found in the microstructure of 9Cr ODS steels. This constituent was reported to be responsible for the superior creep and high-temperature strength. Using optical microscopy of an air-cooled batch of ODS EUROFER, inhomogeneous regions in the microstructure have been found with similar appearance to previously reported residual ferrite. Detailed microstructural investigations have been carried out on the inhomogeneous regions using site-specific nanoindentation, scanning electron microscopy including electron backscatter diffraction, and transmission electron microscopy. It is demonstrated that the inhomogeneous regions are formed due to imperfect mechanical alloying leading to the absence of oxide nanoparticles and consequently lower hardness. It is concluded that optical microscopy is insufficient to distinguish beneficial residual ferrite from undesired particle-free regions. The weakness of the inhomogeneous regions is attributed to the absence of nanoparticles and a lower dislocation density. Our findings are underpinned by the consistency between the calculated theoretical yield strength, the yield strength converted from the indentation hardness and the yield strength obtained from tensile testing.

Ferritic-martensitic ODS steels are one of the candidate materials for Gen-IV nuclear fission and fusion reactors. Residual ferrite was often found in the microstructure of 9Cr ODS steels. This constituent was reported to be responsible for the superior creep and high-temperature strength. Using optical microscopy of an air-cooled batch of ODS EUROFER, inhomogeneous regions in the microstructure have been found with similar appearance to previously reported residual ferrite. Detailed microstructural investigations have been carried out on the inhomogeneous regions using site-specific nanoindentation, scanning electron microscopy including electron backscatter diffraction, and transmission electron microscopy. It is demonstrated that the inhomogeneous regions are formed due to imperfect mechanical alloying leading to the absence of oxide nanoparticles and consequently lower hardness. It is concluded that optical microscopy is insufficient to distinguish beneficial residual ferrite from undesired particle-free regions. The weakness of the inhomogeneous regions is attributed to the absence of nanoparticles and a lower dislocation density. Our findings are underpinned by the consistency between the calculated theoretical yield strength, the yield strength converted from the indentation hardness and the yield strength obtained from tensile testing.

We present an evolution-strategy based approach to solve the magnitude least squares (MLS) design problem of low flip-angle slice-selective parallel transmit RF pulses for ultra-high field MRI using SAR and peak-RF-constraints. A combined transmit k-space trajectory and RF pulse weight optimization is proposed in two algorithmic steps. The first step is a coarse grid search to find an initial solution that fulfills all constraints for the subsequent multistage optimization. This avoids convergence to the next nearest local minimum. The second step attempts to refine the results using multiple evolution strategies. We compare the performance of our approach with the non-convex optimization methods described in the literature. The proposed algorithm converges for phantom and in vivo data and only requires an initial estimate of the range of suitable regularization parameters. It demonstrates improved excitation homogeneity compared to published spoke-design methods and allows optimization for homogeneity with a subsequent reduction in the SAR burden. Moreover, excitation homogeneity and the SAR burden can be balanced against each other, enabling a further reduction in SAR at the cost of minor relaxations in excitation homogeneity. This feature makes the algorithm a good candidate for SAR limited sequences in ultra-high field imaging. The algorithm is validated using phantom and in vivo measurements obtained with a 16-channel transmit array at 9.4 T.

The Human Connectome Project (HCP) has a 7T component that aims to study the human brain's organization and function with high spatial and temporal resolution fMRI and diffusion-weighted acquisitions. For whole brain applications at 7T, a major weakness however remains the heterogeneity of the radiofrequency transmission field (B1+ ), which prevents from achieving an optimal signal and contrast homogeneously throughout the brain. In this work, we use parallel transmission (pTX) Universal Pulses (UP) to improve the flip angle homogeneity and demonstrate their application to highly accelerated multi-band EPI (MB5 and GRAPPA2, as prescribed in the 7T HCP protocol) sequence, but also to acquire at 7T B1+ -artefact-free T1 - and T2 -weighted anatomical scans used in the pre-processing pipeline of the HCP protocol. As compared to typical implementations of pTX, the proposed solution is fully operator-independent and allows "plug and play" exploitation of the benefits offered by multi-channel transmission. Validation in five healthy adults shows that the proposed technique achieves a flip angle homogeneity comparable to that of a clinical 3 T system. Compared to standard single-channel transmission, the use of UPs at 7T yielded up to a two-fold increase of the temporal signal-to-noise ratio in the temporal lobes as well as improved detection of functional connectivity in the brain regions most strongly affected by B1+ inhomogeneity.

The steel–concrete interface (SCI) is known to influence corrosion of steel in concrete. However, due to the numerous factors affecting the SCI—including steel properties, concrete properties, execution, and exposure conditions—it remains unclear which factors have the most dominant impact on the susceptibility of reinforced concrete to corrosion. In this literature review, prepared by members of RILEM technical committee 262-SCI, an attempt is made to elucidate the effect of numerous SCI characteristics on chloride-induced corrosion initiation of steel in concrete. We use a method to quantify and normalize the effect of individual SCI characteristics based on different literature results, which allows comparing them in a comprehensive context. It is found that the different SCI characteristics have received highly unbalanced research attention. Parameters such as w/b ratio and cement type have been studied most extensively. Interestingly, however, literature consistently indicates that those parameters have merely a moderate effect on the corrosion susceptibility of steel in concrete. Considerably more pronounced effects were identified for (1) steel properties, including metallurgy, presence of mill scale or rust layers, and surface roughness, and (2) the moisture state. Unfortunately, however, these aspects have received comparatively little research attention. Due to their apparently strong influence, future corrosion studies as well as developments towards predicting corrosion initiation in concrete would benefit from considering those aspects. Particularly the working mechanisms related to the moisture conditions in microscopic and macroscopic voids at the SCI is complex and presents major opportunities for further research in corrosion of steel in concrete., Accepted Author Manuscript, Materials and Environment

Welding is one of the most often applied joining procedures for different metallic structures. Due to the nature of the process, i.e. heating, additional material (for some methods), usage of protective atmosphere and cooling, it typically causes inhomogeneity in the joint zone. This inhomogeneity influences the fracture behaviour, and can significantly endanger the integrity of the welded structures. This work deals with micromechanical criteria for initiation and development of ductile fracture in welded joints. These criteria are applied within the framework of local approach to fracture, through experimental-numerical procedure. Welded joints with a single weld metal or two different weld metals are examined; the influence of constraint and heterogeneity (mismatch) is analysed. Also, the defects in the heat affected zone are considered, as well as pipeline materials with sharp and blunt initial defects. Micromechanical model CGM, complete Gurson model, is used for modelling the damage initiation and development in the material.

The Human Connectome Project (HCP) has a 7T component that aims to study the human brain's organization and function with high spatial and temporal resolution fMRI and diffusion-weighted acquisitions. For whole brain applications at 7T, a major weakness however remains the heterogeneity of the radiofrequency transmission field (B1+ ), which prevents from achieving an optimal signal and contrast homogeneously throughout the brain. In this work, we use parallel transmission (pTX) Universal Pulses (UP) to improve the flip angle homogeneity and demonstrate their application to highly accelerated multi-band EPI (MB5 and GRAPPA2, as prescribed in the 7T HCP protocol) sequence, but also to acquire at 7T B1+ -artefact-free T1 - and T2 -weighted anatomical scans used in the pre-processing pipeline of the HCP protocol. As compared to typical implementations of pTX, the proposed solution is fully operator-independent and allows "plug and play" exploitation of the benefits offered by multi-channel transmission. Validation in five healthy adults shows that the proposed technique achieves a flip angle homogeneity comparable to that of a clinical 3 T system. Compared to standard single-channel transmission, the use of UPs at 7T yielded up to a two-fold increase of the temporal signal-to-noise ratio in the temporal lobes as well as improved detection of functional connectivity in the brain regions most strongly affected by B1+ inhomogeneity.

The steel–concrete interface (SCI) is known to influence corrosion of steel in concrete. However, due to the numerous factors affecting the SCI—including steel properties, concrete properties, execution, and exposure conditions—it remains unclear which factors have the most dominant impact on the susceptibility of reinforced concrete to corrosion. In this literature review, prepared by members of RILEM technical committee 262-SCI, an attempt is made to elucidate the effect of numerous SCI characteristics on chloride-induced corrosion initiation of steel in concrete. We use a method to quantify and normalize the effect of individual SCI characteristics based on different literature results, which allows comparing them in a comprehensive context. It is found that the different SCI characteristics have received highly unbalanced research attention. Parameters such as w/b ratio and cement type have been studied most extensively. Interestingly, however, literature consistently indicates that those parameters have merely a moderate effect on the corrosion susceptibility of steel in concrete. Considerably more pronounced effects were identified for (1) steel properties, including metallurgy, presence of mill scale or rust layers, and surface roughness, and (2) the moisture state. Unfortunately, however, these aspects have received comparatively little research attention. Due to their apparently strong influence, future corrosion studies as well as developments towards predicting corrosion initiation in concrete would benefit from considering those aspects. Particularly the working mechanisms related to the moisture conditions in microscopic and macroscopic voids at the SCI is complex and presents major opportunities for further research in corrosion of steel in concrete., Accepted Author Manuscript, Materials and Environment

The steel–concrete interface (SCI) is known to influence corrosion of steel in concrete. However, due to the numerous factors affecting the SCI—including steel properties, concrete properties, execution, and exposure conditions—it remains unclear which factors have the most dominant impact on the susceptibility of reinforced concrete to corrosion. In this literature review, prepared by members of RILEM technical committee 262-SCI, an attempt is made to elucidate the effect of numerous SCI characteristics on chloride-induced corrosion initiation of steel in concrete. We use a method to quantify and normalize the effect of individual SCI characteristics based on different literature results, which allows comparing them in a comprehensive context. It is found that the different SCI characteristics have received highly unbalanced research attention. Parameters such as w/b ratio and cement type have been studied most extensively. Interestingly, however, literature consistently indicates that those parameters have merely a moderate effect on the corrosion susceptibility of steel in concrete. Considerably more pronounced effects were identified for (1) steel properties, including metallurgy, presence of mill scale or rust layers, and surface roughness, and (2) the moisture state. Unfortunately, however, these aspects have received comparatively little research attention. Due to their apparently strong influence, future corrosion studies as well as developments towards predicting corrosion initiation in concrete would benefit from considering those aspects. Particularly the working mechanisms related to the moisture conditions in microscopic and macroscopic voids at the SCI is complex and presents major opportunities for further research in corrosion of steel in concrete.

In this paper we consider the case of a functionally graded heat-conducting hollowed cylinder. Our purpose is to investigate the consequences of the material inhomogeneity on the decay of Saint-Venant end effects in the case of linear isotropic rigid solids. The mathematical issues involve the implications of spatial inhomogeneity on the decay rates of solutions to Dirichlet boundary-value problems. The rate of decay is characterized in terms of the smallest eigenvalue of a Sturm–Liouville problem. We first consider the case where the inhomogeneity depends on the radius of the cross-section, but later we also consider the case where the inhomogeneity also depends on the axial variable. The last section considers the case where the cross-section is increasing. Some tables and figures illustrate our estimates., Peer Reviewed, Postprint (author's final draft)

© 2017 American Physical Society. This work has been supported by the Spanish MICINNs Consolider-Ingenio 2010 Programme under MultiDark Grant No. CSD2009-00064, MINECO Centro de Excelencia Severo Ochoa Programme under Grant No. SEV-2012-0249, and MINECO Grants No. FIS2014- 52837-P, AYA-2012-31101 and AYA2014-60641-C2-1-P. FDA acknowledges financial support from ‘la Caixa’- Severo Ochoa doctoral fellowship., We study the possible effects of classical gravitational backgrounds on the Higgs field through the modifications induced in the one-loop effective potential and the vacuum expectation value of the energymomentum tensor. We concentrate our study on the Higgs self-interaction contribution in a perturbed FRW metric. For weak and slowly varying gravitational fields, a complete set of mode solutions for the KleinGordon equation is obtained to leading order in the adiabatic approximation. Dimensional regularization has been used in the integral evaluation, and a detailed study of the integration of nonrational functions in this formalism has been presented. As expected, the regularized effective potential contains the same divergences as in flat spacetime, which can be renormalized without the need of additional counterterms. We find that, in contrast with other regularization methods, even though metric perturbations affect the mode solutions, they do not contribute to the leading adiabatic order of the potential. We also obtain explicit expressions of the complete energy-momentum tensor for general nonminimal coupling in terms of the perturbed modes. The corresponding leading adiabatic contributions are also obtained., Ministerio de Ciencia e Innovación (MICINN), Ministerio de Economía y Competitividad (MINECO), Centro de Excelencia Severo Ochoa, Consolider-Ingenio 2010 Programme, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

PURPOSE: To eliminate a slice-position-dependent excitation error commonly observed in bipolar-gradient composite excitations such as spokes pulses in parallel transmission.THEORY AND METHODS: An undesired timing delay between subpulses in the composite pulse and their bipolar slice-selective gradient is hypothesized to cause the error. A mathematical model is presented here to relate this mismatch to an induced slice-position-dependent phase difference between the subpulses. A new navigator method is proposed to measure the timing mismatch and eliminate the error. This is demonstrated at 7 Tesla with flip-angle maps measured by a presaturation turbo-flash sequence and in vivo images acquired by a simultaneous multislice/echo-planar imaging (SMS-EPI) sequence.RESULTS: Error-free flip-angle maps were obtained in two ways: 1) by correcting the time delay directly and 2) by applying the corresponding slice-position-dependent phase differences to the subpulses. This confirms the validity of the mathematical description. The radiofrequency (RF)-gradient delay measured by the navigator method was of 6.3 μs, which agreed well with the estimate from flip-angle maps at different delay times. By applying the timing correction, accurately excited EPI images were acquired with bipolar dual-spokes SMS-2 excitations.CONCLUSION: An effective correction is proposed to mitigate slice-position-dependent errors in bipolar composite excitations caused by undesired RF-gradient timing delays. Magn Reson Med, 2016. © 2016 International Society for Magnetic Resonance in Medicine.

The paper is devoted to the analysis of theolinguistics, an incipient philological branch at the junction of theology, religious anthropology and linguistics. Having appeared in the 70-s of the 20-th century theolinguistics was meant as a branch of linguistics seeking to describe how human discourse may be employed to refer to the divine and how language operates in ‘religious’ situations. Further developments of this branch of learning broadened the scope of scientific interests to the study of the relationship between language and religious thought and practice illustrated by ritual, sacred texts, preaching, doctrinal statements and private affirmations of belief. Slavonic linguists took up the idea of the western philologists at the end of the 20-th century. Since then they have been working out a generic system of theolinguistics including its terminological apparatus, methodology, goals and tasks. The main difficulties theolinguistics is confronted with can be both of objective and subjective characters. The main objective problem is gnoseological roots of its constituents (scientific and theological). On the other hand it is inhomogeneity of theolinguistics, that can be helpful to solve many problems incapable of being solved by means of purely scientific methods., В статье анализируется новое направление в языкознании, именуемое теолингвистикой, проводится сопоставление целей и задач новой дисциплины в западной и славянской лингвистике, выявляются основные проблемы, возникающие в процессе становления теолингвистического подхода к изучению языка религии., В статті аналізується новий напрямок у мовознавстві – теолінгвістика, здійснюється зіставлення цілей та завдань нової дисципліни в західній та слов’янській лінгвістиці, виявляються основні проблеми, що виникають у процесі становлення теолінгвістичного підходу до вивчення мови релігії.

Although the steel–concrete interface (SCI) is widely recognized to influence the durability of reinforced concrete, a systematic overview and detailed documentation of the various aspects of the SCI are lacking. In this paper, we compiled a comprehensive list of possible local characteristics at the SCI and reviewed available information regarding their properties as well as their occurrence in engineering structures and in the laboratory. Given the complexity of the SCI, we suggested a systematic approach to describe it in terms of local characteristics and their physical and chemical properties. It was found that the SCI exhibits significant spatial inhomogeneity along and around as well as perpendicular to the reinforcing steel. The SCI can differ strongly between different engineering structures and also between different members within a structure; particular differences are expected between structures built before and after the 1970/1980s. A single SCI representing all on-site conditions does not exist. Additionally, SCIs in common laboratory-made specimens exhibit significant differences compared to engineering structures. Thus, results from laboratory studies and from practical experience should be applied to engineering structures with caution. Finally, recommendations for further research are made., Materials and Environment

Although the steel–concrete interface (SCI) is widely recognized to influence the durability of reinforced concrete, a systematic overview and detailed documentation of the various aspects of the SCI are lacking. In this paper, we compiled a comprehensive list of possible local characteristics at the SCI and reviewed available information regarding their properties as well as their occurrence in engineering structures and in the laboratory. Given the complexity of the SCI, we suggested a systematic approach to describe it in terms of local characteristics and their physical and chemical properties. It was found that the SCI exhibits significant spatial inhomogeneity along and around as well as perpendicular to the reinforcing steel. The SCI can differ strongly between different engineering structures and also between different members within a structure; particular differences are expected between structures built before and after the 1970/1980s. A single SCI representing all on-site conditions does not exist. Additionally, SCIs in common laboratory-made specimens exhibit significant differences compared to engineering structures. Thus, results from laboratory studies and from practical experience should be applied to engineering structures with caution. Finally, recommendations for further research are made., Materials and Environment

Phase unwrapping is a classic signal processing problem and an unavoidable procedure that can be faced with in a variety of applications which are interested in the phase, such as synthetic aperture radar (SAR), field mapping in magnetic resonance imaging (MRI), wavefront distortion measurement of adaptive optics, interferometry, and surface shape measurement. Although phase unwrapping is one of the most challenging tasks in signal processing because of the presence of residues, noise in the data, discontinuities or other phase particularities, there are many successful phase unwrapping techniques and algorithms that have been developed in the last decades. In this thesis, we present a modified algorithm based on the Andris‟s method which is dependent on the difference in two echo times (TE). The proposed algorithm is confirmed by using simulated phase MR data which are highly distorted by large magnetic field inhomogeneity (∆B) or long echo time (TE). The approach is evaluated by comparison to other unwrapping algorithms and results show that the proposed algorithm has better accuracy.

Although the steel–concrete interface (SCI) is widely recognized to influence the durability of reinforced concrete, a systematic overview and detailed documentation of the various aspects of the SCI are lacking. In this paper, we compiled a comprehensive list of possible local characteristics at the SCI and reviewed available information regarding their properties as well as their occurrence in engineering structures and in the laboratory. Given the complexity of the SCI, we suggested a systematic approach to describe it in terms of local characteristics and their physical and chemical properties. It was found that the SCI exhibits significant spatial inhomogeneity along and around as well as perpendicular to the reinforcing steel. The SCI can differ strongly between different engineering structures and also between different members within a structure; particular differences are expected between structures built before and after the 1970/1980s. A single SCI representing all on-site conditions does not exist. Additionally, SCIs in common laboratory-made specimens exhibit significant differences compared to engineering structures. Thus, results from laboratory studies and from practical experience should be applied to engineering structures with caution. Finally, recommendations for further research are made.

Запропоновано створення класифікатора на основі дискретного нормального ортогонального перетворення для оцінки доцільності розв’язання зворотної задачі електроімпедансної томографії за результатами вимірювань напруг на електродах по обводу контуру фантома. Створено класифікатор оцінки чутливості, який на основі обчислення коефіцієнтів трансформант сукупностей виміряних напруг дозволяє зробити висновок про потенційну можливість отримання достовірного результату реконструкції. Проведено обчислення коефіцієнтів трансформант для випадків отримання достовірних результатів візуалізації та для випадків, коли за результатами комп’ютерного моделювання напруг фантома та їх натурних вимірювань отримання надійної реконструкції розподілення опорів усередині фантома не є можливим. Отримані результати свідчать про можливість створення класифікаторів оцінки чутливості, для чого слід в процесі розв’язання задачі реконструкції створювати відповідну базу даних надійних та ненадійних розв’язків.

Обґрунтовано використання методу модифікацій для розв’язання прямої задачі електроімпедансної томографії, що являє собою обчислення напруг по обводу контуру фантома при наданих у поточному наближенні розподілах поверхневих провідностей. Наведено класичний алгоритм розв’язання зворотної задачі електроімпедансної томографії з використанням методу Ньютона–Рафсона, тобто уточнення поверхневих провідностей за результатами аналізу. Описано метод зон провідності для зменшення порядків і часу розрахунків (перехід від розв’язання рівняння порядку 1000 до розв’язання 16 рівнянь 14-го порядку). Подано метод регуляризації за А.М. Тихоновим для вирішення проблеми поганої зумовленості матриці похідних від передаточних опорів по поверхневих провідностях при розв’язанні задачі реконструкції образу в електроімпедансній томографії. Наведено алгоритм швидкої модифікації ітераційного алгоритму регуляризації, який дає можливість розв’язувати задачу за 10–20 кроків замість 1000–1000000 кроків класичного алгоритму. Подано приклади розподілу провідностей реконструйованих образів для фантомів з різними неоднорідностями. Показано доцільність створення класифікатора для оцінки наявності або відсутності неоднорідності порівняно з рівномірним фантомом., The usage of modification method for direct EIT problem solving is substantiated. The voltages on phantom contour with known current approximation of surface conductivity distribution are calculated. The classical algorithm with Newton–Raphson method for inverse EIT problem solving is shown. That is “refinement” of surface conductivities by results of analysis. The conductivity zones method to reduce the order and time of calculations is described (transition from solution of the equation with 1000 order to 16 times solving the equations with 14 order). The regularization method by A.N. Tykhonov to solve the problem of ill-conditioned derivatives matrices from transfer resistances (nodal voltages) on surface zones conductivities solving the image reconstruction problem in EIT is considered. The algorithm of fast iterative updating regularization algorithm is given. It allows solving the problem by 10–20 steps instead of 1000–1000000 steps of classic algorithm. The expediency of classifier creating to assess the presence or absence of heterogeneity compared to uniform phantom is shown.

Introduction. The classifier creation on the base of discrete normal orthogonal transformation to access the advisability of inverse Electrical Impedance Tomography (EIT) solving is proposed. Measured voltages on electrodes on the phantom outline are output data for EIT inverse problem solution. The necessity in preliminary assessment exists because the process of solving is labor-intensive and may not have the reliable results. The results. The sensitivity access classifier is developed. It allows to make a conclusion about potential possibility of reliable reconstruction result obtaining from calculating the transformant coefficients of measured voltages sets. The transformant coefficients are calculated in cases of reliable visualization results obtaining and in cases where the results of computer simulation phantom voltages and their measurements obtaining the reliable reconstruction of resistance distribution is not possible. The calculations are conducted for different inhomogeneities, with different values of conductivity and locations. Conclusions. The results suggest the possibility of creation the classifier for sensitivity access. The appropriate database of reliable and unreliable solutions should be formed in the process of reconstruction problem solving., Предложено создание классификатора на основе дискретного нормального ортогонального преобразования для оценки целеснообразности решения обратной задачи электроимпедансной томографии по результатам измерений напряжений на электродах по обводу контура фантома. Создано классификатор оценки чувствительности, который на основе вычисления коэффициентов трансформант сукупностей измеренных напряжений позволяет сделать вывод про потенциальную возможность получения достоверного результата реконструкции. Проведено вычисления коэффициентов трансформант для случаев получения достоверных результатов визуализации и для случаев, когда по результатам компьютерного моделирования напряжений фантома и их натурных измерений получения надежной реконструкции распределения сопротивлений внутри фантома не представляется возможным. Полученные результаты свидетельствуют о возможности создания классификаторов оценки чувствительности, для чего следует в процессе решения задачи реконструкции создавать базу данных надежных и ненадежных решений., Запропоновано створення класифікатора на основі дискретного нормального ортогонального перетворення для оцінки доцільності розв’язання зворотної задачі електроімпедансної томографії за результатами вимірювань напруг на електродах по обводу контуру фантома. Створено класифікатор оцінки чутливості, який на основі обчислення коефіцієнтів трансформант сукупностей виміряних напруг дозволяє зробити висновок про потенційну можливість отримання достовірного результату реконструкції. Проведено обчислення коефіцієнтів трансформант для випадків отримання достовірних результатів візуалізації та для випадків, коли за результатами комп’ютерного моделювання напруг фантома та їх натурних вимірювань отримання надійної реконструкції розподілення опорів усередині фантома не є можливим. Отримані результати свідчать про можливість створення класифікаторів оцінки чутливості, для чого слід в процесі розв’язання задачі реконструкції створювати відповідну базу даних надійних та ненадійних розв’язків.

PurposeSimultaneous multislice (SMS) imaging can significantly increase image acquisition rates and improve temporal resolution and contrast in gradient-echo blood oxygen level-dependent (BOLD) functional MRI (fMRI) experiments. Through-plane signal loss due to B-0 inhomogeneities at air-tissue interfaces limits fMRI of structures near the nasal cavity and ear canals. This study implemented spectral-spatial (SPSP) radiofrequency pulses for reduced through-plane signal loss across multiple simultaneously excited slices. Theory and MethodsMultiband (MB) and power independent of number of slices (PINS) methods are combined with SPSP excitation for signal loss compensation in slice-accelerated human brain imaging. Nine simultaneous slices of 5-mm thickness and 20 mm apart were excited using standard MB radiofrequency pulses and the proposed SPSP-SMS pulses, yielding coverage of 36 slices in four shots with 350-ms volume pulse repetition time. The pulses were compared in breath-hold fMRI at 3T. ResultsThe SPSP-SMS pulses recovered approximate to 45% of voxels with signal loss in standard SMS images. Activation in areas of signal recovery increased by 26.4% using a 12.6-ms SPSP-MB pulse and 20.3% using a 12.1-ms SPSP-PINS pulse. ConclusionsIt is demonstrated that SPSP-SMS pulses can improve BOLD sensitivity in areas of signal loss across simultaneous multiple slices. Magn Reson Med 72:1342-1352, 2014. (c) 2013 Wiley Periodicals, Inc.

It is assumed that reference materials for analytical methods must be homogeneous, i.e. have the same concentration of the relevant element(s) overall, to ensure that they can be used reliably to get comparison values during the analysis with non absolute methods. To ensure such homogeneity becomes increasingly difficult with increasing resolution, up to the point that it is not possible for several microanalytical methods. We propose a way to get reliable comparison values with some types of inhomogeneous material. This is based on multiple probing the reference material. The minimal number of probing spots required for a certain precision level can be derived from the variance calculations. However, using adequate models of local heterogeneity can greatly reduce that number: Geostatistics can be used in random, systematic and periodic heterogeneities, while robust methods are useful in cases of nugget heterogeneities.

It is assumed that reference materials for analytical methods must be homogeneous, i.e. have the same concentration of the relevant element(s) overall, to ensure that they can be used reliably to get comparison values during the analysis with non absolute methods. To ensure such homogeneity becomes increasingly difficult with increasing resolution, up to the point that it is not possible for several microanalytical methods. We propose a way to get reliable comparison values with some types of inhomogeneous material. This is based on multiple probing the reference material. The minimal number of probing spots required for a certain precision level can be derived from the variance calculations. However, using adequate models of local heterogeneity can greatly reduce that number: Geostatistics can be used in random, systematic and periodic heterogeneities, while robust methods are useful in cases of nugget heterogeneities.

PurposeSimultaneous multislice (SMS) imaging can significantly increase image acquisition rates and improve temporal resolution and contrast in gradient-echo blood oxygen level-dependent (BOLD) functional MRI (fMRI) experiments. Through-plane signal loss due to B-0 inhomogeneities at air-tissue interfaces limits fMRI of structures near the nasal cavity and ear canals. This study implemented spectral-spatial (SPSP) radiofrequency pulses for reduced through-plane signal loss across multiple simultaneously excited slices. Theory and MethodsMultiband (MB) and power independent of number of slices (PINS) methods are combined with SPSP excitation for signal loss compensation in slice-accelerated human brain imaging. Nine simultaneous slices of 5-mm thickness and 20 mm apart were excited using standard MB radiofrequency pulses and the proposed SPSP-SMS pulses, yielding coverage of 36 slices in four shots with 350-ms volume pulse repetition time. The pulses were compared in breath-hold fMRI at 3T. ResultsThe SPSP-SMS pulses recovered approximate to 45% of voxels with signal loss in standard SMS images. Activation in areas of signal recovery increased by 26.4% using a 12.6-ms SPSP-MB pulse and 20.3% using a 12.1-ms SPSP-PINS pulse. ConclusionsIt is demonstrated that SPSP-SMS pulses can improve BOLD sensitivity in areas of signal loss across simultaneous multiple slices. Magn Reson Med 72:1342-1352, 2014. (c) 2013 Wiley Periodicals, Inc.

Introduction. The concept of sensitivity in Electrical Impedance Tomography is introduced (first – fourth type). The experimental researches measuring the voltages on the phantom outline are conducted on the created layout (for uniform cylindrical vessel with brine and placed inhomogeneities in a vessel). The main part. The inverse problems are solved for simulated on PC phantom (the third type sensitivity) and from measured results (the fourth type sensitivity) by conductivity zones method using regularization by A. Tykhonov. The sensitivity to conductivity increasing of elements inside the phantom is significantly less than the sensitivity to resistance increasing. The results of measured voltages processing and the results of projection reconstruction (obtained from mathematical model and from measured results) are described. Conclusions. The satisfactory agreements of reconstruction results between themselves and with mathematical and measured phantoms are shown., Введено понятие чувствительности в электроимпедансной томографии (первого…четвертого рода). Проведено экспериментальные исследования по измерению напряжений по обводу контура на созданном макете (для равномерного цилиндрического сосуда с раствором соли и с размещенными в сосуде неоднородностями). Методом зон проводимости (с использованием регуляризации по А.Н. Тихонову) решено обратные задачи электроимпедансной томографии для фантома, имитированного на ЭВМ (чувствительность третьего рода) и по результатам натурных измерений (чувствительность четвертого рода). Чувствительность (первого…четвертого рода) к увеличению проводимости графоэлементов в середине фантома оказалась значительно меньшей, чем чувствительность к увеличению сопротивления. Приведено результаты обработки измеренных напряжений и результаты реконструкции по проекциям, полученным по математической модели и по результатам натурных измерений. Показано удовлетворительное совпадение полученных результатов реконструкции между собою, а также с математическим и натурным фантомами., Введено поняття чутливості в електроімпедансній томографії (першого…четвертого роду). Проведено експериментальні дослідження по вимірюванню напруг по обводу контуру на створеному макеті (для рівномірного циліндричної судини з розчином солі та з розміщеними в судині неоднорідностями). Методом зон провідностей (з використанням регуляризації за А.Н. Тихоновим) розв’язано зворотні задачі електроімпедансної томографії для фантома, імітованого на ЕОМ (чутливість третього роду) та за результатами натурних вимірювань (чутливість четвертого роду). Чутливість (першого…четвертого роду) до збільшення провідності графоелементів усередині фантома виявилася значно меншою, ніж чутливість до збільшення опору. Наведено результати оброблення виміряних напруг та результати реконструкції за проекціями, отриманими за математичною моделлю та за результатами натурних вимірювань. Показане задовільне співпадіння отриманих результатів реконструкції між собою та з математичним і натурним фантомами.

Введено поняття чутливості в електроімпедансній томографії (першого…четвертого роду). Проведено експериментальні дослідження по вимірюванню напруг по обводу контуру на створеному макеті (для рівномірного циліндричної судини з розчином солі та з розміщеними в судині неоднорідностями). Методом зон провідностей (з використанням регуляризації за А.Н. Тихоновим) розв’язано зворотні задачі електроімпедансної томографії для фантома, імітованого на ЕОМ (чутливість третього роду) та за результатами натурних вимірювань (чутливість четвертого роду). Чутливість (першого…четвертого роду) до збільшення провідності графоелементів усередині фантома виявилася значно меншою, ніж чутливість до збільшення опору. Наведено результати оброблення виміряних напруг та результати реконструкції за проекціями, отриманими за математичною моделлю та за результатами натурних вимірювань. Показане задовільне співпадіння отриманих результатів реконструкції між собою та з математичним і натурним фантомами.

The effect of thickness, curing temperature and solvent on the structural inhomogeneity of several types of organic coatings has been investigated. The local distribution of electrochemical resistance was studied using a wire beam multielectrode array, while the inhomogeneity at a larger scale was examined using ∼3 cm2 area detached coatings. Physicomechanical tests were also employed to address the structural changes occurring because of variation in curing temperature and the type (or absence) of solvent. Results acquired by wire beam electrode and from the detached coatings showed that increasing the thickness and curing temperature improves the homogeneity of the coating as does elimination of solvent. Waterborne coatings exhibited a relatively homogeneous low resistance with a resistance lower than the threshold required for effective corrosion protection. Results of physicomechanical examination suggest that unreacted functional groups and water absorption are of the main causes of formation of structural defects in organic coatings.

The effect of thickness, curing temperature and solvent on the structural inhomogeneity of several types of organic coatings has been investigated. The local distribution of electrochemical resistance was studied using a wire beam multielectrode array, while the inhomogeneity at a larger scale was examined using ∼3 cm2 area detached coatings. Physicomechanical tests were also employed to address the structural changes occurring because of variation in curing temperature and the type (or absence) of solvent. Results acquired by wire beam electrode and from the detached coatings showed that increasing the thickness and curing temperature improves the homogeneity of the coating as does elimination of solvent. Waterborne coatings exhibited a relatively homogeneous low resistance with a resistance lower than the threshold required for effective corrosion protection. Results of physicomechanical examination suggest that unreacted functional groups and water absorption are of the main causes of formation of structural defects in organic coatings.

The effect of thickness, curing temperature and solvent on the structural inhomogeneity of several types of organic coatings has been investigated. The local distribution of electrochemical resistance was studied using a wire beam multielectrode array, while the inhomogeneity at a larger scale was examined using ∼3 cm2 area detached coatings. Physicomechanical tests were also employed to address the structural changes occurring because of variation in curing temperature and the type (or absence) of solvent. Results acquired by wire beam electrode and from the detached coatings showed that increasing the thickness and curing temperature improves the homogeneity of the coating as does elimination of solvent. Waterborne coatings exhibited a relatively homogeneous low resistance with a resistance lower than the threshold required for effective corrosion protection. Results of physicomechanical examination suggest that unreacted functional groups and water absorption are of the main causes of formation of structural defects in organic coatings.

The effect of thickness, curing temperature and solvent on the structural inhomogeneity of several types of organic coatings has been investigated. The local distribution of electrochemical resistance was studied using a wire beam multielectrode array, while the inhomogeneity at a larger scale was examined using ∼3 cm2 area detached coatings. Physicomechanical tests were also employed to address the structural changes occurring because of variation in curing temperature and the type (or absence) of solvent. Results acquired by wire beam electrode and from the detached coatings showed that increasing the thickness and curing temperature improves the homogeneity of the coating as does elimination of solvent. Waterborne coatings exhibited a relatively homogeneous low resistance with a resistance lower than the threshold required for effective corrosion protection. Results of physicomechanical examination suggest that unreacted functional groups and water absorption are of the main causes of formation of structural defects in organic coatings.

The Heusler-derived multiferroic alloy Ni50 xCoxMn40Sn10 has recently been shown to exhibit, at just above room temperature, a highly reversible martensitic phase transformation with an unusually large magnetization change. In this work the nature of the magnetic ordering above and below this transformation has been studied in detail in the critical composition range x = 6 8 via temperature-dependent (5 600 K) magnetometry and smallangle neutron scattering (SANS). We observe fairly typical paramagnetic to long-range-ordered ferromagnetic phase transitions on cooling to 420 430 K, with the expected critical spin fluctuations, followed by first-order martensitic phase transformations to a nonferromagnetic state below 360 390 K. The staticmagnetization reveals complex magnetism in this low-temperature nonferromagnetic phase, including a Langevin-like field dependence, distinct spin freezing near 60 K, and significant exchange bias effects, consistent with superparamagnetic blocking of ferromagnetic clusters of nanoscopic dimensions. We demonstrate that these spin clusters, whose existence has been hypothesized in a variety of martensitic alloys exhibiting competition between ferromagnetic and antiferromagnetic exchange interactions, can be directly observed by SANS. The scattering data are consistent with a liquidlike spatial distribution of interacting magnetic clusters with a mean center-to-center spacing of 12 nm. Considering the behavior of the superparmagnetism, cooling-field and temperature-dependent exchange bias, and magnetic SANS, we discuss in detail the physical form and origin of these spin clusters, their intercluster interactions, the nature of the ground-state magnetic ordering in the martensitic phase, and the implications for our understanding of such alloy systems., Published in Physical Review B, v85 article ID 134450, 27 Apr 2012. Prepared in collaboration with the Department of Physics, American University of Sharjah, United Arab Emirates, NIST Center for Neutron Research, National Institute for Standards and Technology, Gaithersburg, MD, and the Department of Aerospace Engineering and Mechanics, University of Minnesota, Minneapolis.

В роботі проведено аналіз точності вимірювань в імпедансній томографії напруг по обводу фантома, необхідної для розрізнення (по вимірюванням) наявності поодиноких неоднорідностей: «маленької» (площа становить 3% від загальної площі фантома), «середньої» (8,5%) та «великої» (19,59%) при різних значеннях поверхневої провідності цих неоднорідностей (на фоні фантома з поверхневою провідністю σ=1). Вимірювання було імітовано розрахунками напруг рівномірного фантома, фантомів з неоднорідностями та обчисленням різниць напруг (прирощень) між рівномірним фантомом та фантомами з неоднорідностями. Показано, що неоднорідності з поверхневою провідністю, більшою, ніж провідність «фону» дають суттєво менші прирощення напруг, ніж неоднорідності з меншими, ніж «фону» провідностям. Проілюстровано (чисельними значеннями прирощень) більшу чутливість при розташуванні неоднорідностей ближче до краю фантома та більших за розміром неоднорідностей. Наведено числові оцінки необхідної точності вимірювань для розглянутих варіантів неоднорідностей.

It has been revealed that when metal is protected by an organic coating, corrosion proceeds through the ionic conduction pathways within the coating layer. An important aspect of polymeric coatings from the protection point of view is their inhomogeneous nature. Phenomena such as lack of cross-linking, inappropriate pigmentation, quick solvent evaporation etc may introduce local micro defects. The rate of diffusion of ions at these micro defects is proportional to the ionic concentration of the solution at which the coating is immersed and therefore they have been known as "D" or direct type areas. On the other hand much of the coating is composed of the highly resistive "I" type area where the ionic resistance increases with increasing the ionic concentration of environment. Traditionally it is believed that a certain level of adhesion is a fundamental requirement to avoid anodic and cathodic areas connecting underneath the coating and this adhesion will be reduced at D area Therefore the ionic resistance and specifically D type areas play an important role to determine the anti-corrosive properties of paint. In the present study a set of alkyd coatings in the form of detached coatings has been examined using DC technique to determine the ratio of D to I types. The significance of thickness, curing condition, solvent type, nano particle incorporation and multi-layer application on D area formation has been investigated. Subsequently a small group of these coatings were applied on steel panels and the long term corrosion behaviour was looked at. Also the adhesion strength of this group of coatings was examined by pull-off method. Results indicate that various factors affect the D to I ratio and these factors therefore will also influence the protection efficiency of the layer but is relatively insensitive to the adhesion strength. Copyright (2012) by the Australasian Corrosion Association.

It has been revealed that when metal is protected by an organic coating, corrosion proceeds through the ionic conduction pathways within the coating layer. An important aspect of polymeric coatings from the protection point of view is their inhomogeneous nature. Phenomena such as lack of cross-linking, inappropriate pigmentation, quick solvent evaporation etc may introduce local micro defects. The rate of diffusion of ions at these micro defects is proportional to the ionic concentration of the solution at which the coating is immersed and therefore they have been known as "D" or direct type areas. On the other hand much of the coating is composed of the highly resistive "I" type area where the ionic resistance increases with increasing the ionic concentration of environment. Traditionally it is believed that a certain level of adhesion is a fundamental requirement to avoid anodic and cathodic areas connecting underneath the coating and this adhesion will be reduced at D area Therefore the ionic resistance and specifically D type areas play an important role to determine the anti-corrosive properties of paint. In the present study a set of alkyd coatings in the form of detached coatings has been examined using DC technique to determine the ratio of D to I types. The significance of thickness, curing condition, solvent type, nano particle incorporation and multi-layer application on D area formation has been investigated. Subsequently a small group of these coatings were applied on steel panels and the long term corrosion behaviour was looked at. Also the adhesion strength of this group of coatings was examined by pull-off method. Results indicate that various factors affect the D to I ratio and these factors therefore will also influence the protection efficiency of the layer but is relatively insensitive to the adhesion strength. Copyright (2012) by the Australasian Corrosion Association.