Exploring configuration-based relaxometry and imaging with balanced steady-state free precession

Over the years, magnetic resonance (MR) imaging has become a fundamental part of the diagnostic process in hospitals worldwide. While the underlying physics dates back more than 60 years with the development of nuclear magnetic resonance, methods that aim to accurately measure the multitude of parameters governing the signal formation are still a topic of active research and developments today. The main aim of this work is to explore the possibilities of developing quantification techniques based on a particular type of MR acquisitions: balanced Steady-State Free Precession (bSSFP). The first chapter briefly introduces the most relevant basic concepts of MR physics that will serve as foundation for the development of the methods presented thereafter. In the second chapter, a new method using multiple bSSFP scans is presented that aim to achieve motion insensitive three-dimensional quantification of relaxation times and thereby improve a recently published technique based on unbalanced gradient echo acquisitions. The method is then evaluated both in phantoms and in vivo studies at 3 T and the results discussed. These include an interesting bias of the method that might provide useful insights into the underlying tissue micro-structure. One the major challenges with bSSFP imaging is the presence of dark regions inside the images, which are due to inhomogeneities in the main magnetic field. In the third chapter, a new approach to address those issues is proposed, termed trueCISS, which combines fast imaging using sparse sampling with compressed sensing reconstructions and multi-parametric fitting, which ultimately allows the synthesis of artefact-free images. Evaluation of the new method is done at 3 T for the human brain. Finally, an extension of the trueCISS technique is presented in chapter four, where the process used to model the data to the signal equation is replaced by a novel algorithm based on configuration theory, which is essentially a representation of the signal formation processes in the Fourier domain. The improved trueCISS imaging method is then successfully evaluated with measurements at ultra high field strengths such as 7 T and 9.4 T which demonstrate the advantages of the new approach

Analytical Optimal Currents for Multiphase PMSMs Under Fault Conditions and Saturation

An original analytical expression is presented in this paper to obtain optimal currents minimizing the copper losses of a multi-phase Permanent Magnet Synchronous Motor (PMSM) under fault conditions. Based on the existing solutions [i]opt1 (without zero sequence of current constraint) and [i]opt2 (with zero sequence constraint), this new expression of currents [i]opt3 is obtained by means of a geometrical representation and can be applied to open-circuit, defect of current regulation, current saturation and machine phase short-circuit fault. Simulation results are presented to validate the proposed approach

Cache-Conscious Offline Real-Time Task Scheduling for Multi-Core Processors

Most schedulability analysis techniques for multi-core architectures assume a single Worst-Case Execution Time (WCET) per task, which is valid in all execution conditions. This assumption is too pessimistic for parallel applications running on multi-core architectures with local instruction or data caches, for which the WCET of a task depends on the cache contents at the beginning of its execution, itself depending on the task that was executed before the task under study. In this paper, we propose two scheduling techniques for multi-core architectures equipped with local instruction and data caches. The two techniques schedule a parallel application modeled as a task graph, and generate a static partitioned non-preemptive schedule. We propose an optimal method, using an Integer Linear Programming (ILP) formulation, as well as a heuristic method based on list scheduling. Experimental results show that by taking into account the effect of private caches on tasks\u27 WCETs, the length of generated schedules is significantly reduced as compared to schedules generated by cache-unaware scheduling methods. The observed schedule length reduction on streaming applications is 11% on average for the optimal method and 9% on average for the heuristic method

Efficient caching in content-centric networks using OpenFlow

International audienceContent-Centric Networking (CCN) is designed for efficient content dissemination and supports caching contents on the path from content providers to content consumers to improve user experience and reduce costs. However, this strategy is not optimal inside a domain. In this paper, we propose a solution to improve caching in CCN using a Software-Defined Networking approach

A transference principle for simultaneous rational approximation

We establish a general transference principle for the irrationality measure of points with $\mathbb{Q}$-linearly independent coordinates in $\mathbb{R}^{n+1}$, for any given integer $n\geq 1$. On this basis, we recover an important inequality of Marnat and Moshchevitin which describes the spectrum of the pairs of ordinary and uniform exponents of rational approximation to those points. For points whose pair of exponents are close to the boundary in the sense that they almost realize the equality, we provide additional information about the corresponding sequence of best rational approximations. We conclude with an application.Comment: 15 page

Internationalization As A Strategy To Enhance Higher Education Quality In Vietnam – Reflections from university leaders

Internationalization is viewed as an important strategy in the context of a country in transition from central planning to market orientation. Efforts to internationalize universities are being carried out at both national and institutional levels. However, to the best of the authors’ knowledge, there has been no study to investigate how individual institutions approach internationalization and what they gain from that process. This paper aims to investigate the enhancement of teachers’ and students’ knowledge and skills using internationalization in Vietnam universities as a strategy

Ceiling turbulent asymmetrical air jets under interaction effects of room architectural elements - a full scale experimental characterization

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Health and the Experience of Childhood in Late Neolithic Vietnam

The article aims to examine aspects of mortuary behavior in late Neolithic/early Bronze Age (Phung Nguyen phase) populations represented at the site of Man Bac in Viet Nam, specifically how mortuary behavior illuminates the role of children, and adult attitudes toward children. In addition, the authors discuss biological characteristics of the human sample, focusing particularly on the child burials, in order to explore aspects of childhood palaeohealth. The methodology includes combining various measures of health-including palaeodemography (childhood mortality), analysis of oral health (Early Childhood Caries or ECC), and analysis of physiological health (Cribra Orbitalia and LEH)-with studies of culturally defined mortuary practices to suggest that, while children clearly had significant health deficiencies and many suffered early deaths, their treatment in mortuary rites shows significant economic value and social esteem placed on children. KEYWORDS: Viet Nam, Neolithic, childhood, health, mortuary behavior, palaeodemography, bioarchaeology

Methodology of tolerance synthesis using bond graph

International audienceThis paper presents a methodology of parametric tolerance synthesis with respect to output aleatory uncertainty specifications. It relies on density function propagation through the inverse model. The resulting parameter density function is then used to synthesize a confidence interval suitable for sizing purpose. As an illustration, parametric tolerance synthesis on a DC motor rotating a load is processed