Application of Advanced Estimation Techniques to a Chemical Plant Model

The paper is aimed at comparing some of the most promising and novel advanced techniques for estimation by assessing their effectiveness on the chemical process benchmark. Global and distributed implementations of the extended Kalman filter are the key elements of the work. In addition, the paper is also aimed at describing and developing a recursive implementation of the autocovariance least square algorithm for the on-line updating of the tuning knobs of the filter, demonstrating its relevance in the performance monitoring of chemical processes

Quantitative Charakterisierung des Lungengewebes mithilfe von Proton-MRT

The focus of the work concerned the development of a series of MRI techniques that were specifically designed and optimized to obtain quantitative and spatially resolved information about characteristic parameters of the lung. Three image acquisition techniques were developed. Each of them allows to quantify a different parameter of relevant diagnostic interest for the lung, as further described below: 1) The blood volume fraction, which represents the amount of lung water in the intravascular compartment expressed as a fraction of the total lung water. This parameter is related to lung perfusion. 2) The magnetization relaxation time T$_2$ und T� *$_2$ , which represents the component of T$_2$ associated with the diffusion of water molecules through the internal magnetic field gradients of the lung. Because the amplitude of these internal gradients is related to the alveolar size, T$_2$ und T� *$_2$ can be used to obtain information about the microstructure of the lung. 3) The broadening of the NMR spectral line of the lung. This parameter depends on lung inflation and on the concentration of oxygen in the alveoli. For this reason, the spectral line broadening can be regarded as a fingerprint for lung inflation; furthermore, in combination with oxygen enhancement, it provides a measure for lung ventilation.Die Magnetresonanztomographie (MRT) stellt ein einzigartiges Verfahren im Bereich der diagnostischen Bildgebung dar, da sie es ermöglicht, eine Vielzahl an diagnostischen Informationen ohne die Verwendung von ionisierenden Strahlen zu erhalten. Die Anwendung von MRT in der Lunge erlaubt es, räumlich aufgelöste Bildinformationen über Morphologie, Funktionalität sowie über die Mikrostruktur des Lungengewebes zu erhalten und diese miteinander zu kombinieren. Für die Diagnose und Charakterisierung von Lungenkrankheiten sind diese Informationen von höchstem Interesse. Die Lungenbildgebung stellt jedoch einen herausfordernden Bereich der MRT dar. Dies liegt in der niedrigen Protondichte des Lungenparenchyms begründet sowie in den relativ kurzen Transversal- Relaxationszeiten T$_2$ und T� *$_2$ , die sowohl die Bildau� ösung als auch das Signal-zu-Rausch Verhältnis beeinträchtigen. Des Weiteren benötigen die vielfältigen Ursachen von physiologischer Bewegung, welche die Atmung, den Herzschlag und den Blut� uss in den Lungengefasen umfassen, die Anwendung von schnellen sowie relativ bewegungsunemp� ndlichen Aufnahmeverfahren, um Risiken von Bildartefakten zu verringern. Aus diesen Gründen werden Computertomographie (CT) und Nuklearmedizin nach wie vor als Goldstandardverfahren gehandhabt, um räumlich aufgelöste Bildinformationen sowohl über die Morphologie als auch die Funktionalität der Lunge zu erhalten. Dennoch stellt die Lungen- MRT aufgrund ihrer Flexibilität sowohl eine vielversprechende Alternative zu den anderen Bildgebungsverfahren als auch eine mögliche Quelle zusätzlicher diagnostischer Informationen dar. ..

Characterization of phase-based methods used for transmission field uniformity mapping: a magnetic resonance study at 3.0 T and 7.0 T.

Knowledge of the transmission field (B1(+)) of radio-frequency coils is crucial for high field (B0  = 3.0 T) and ultrahigh field (B0 ≥7.0 T) magnetic resonance applications to overcome constraints dictated by electrodynamics in the short wavelength regime with the ultimate goal to improve the image quality. For this purpose B1(+) mapping methods are used, which are commonly magnitude-based. In this study an analysis of five phase-based methods for three-dimensional mapping of the B1(+) field is presented. The five methods are implemented in a 3D gradient-echo technique. Each method makes use of different RF-pulses (composite or off-resonance pulses) to encode the effective intensity of the B1(+) field into the phase of the magnetization. The different RF-pulses result in different trajectories of the magnetization, different use of the transverse magnetization and different sensitivities to B1(+) inhomogeneities and frequency offsets, as demonstrated by numerical simulations. The characterization of the five methods also includes phantom experiments and in vivo studies of the human brain at 3.0 T and at 7.0 T. It is shown how the characteristics of each method affect the quality of the B1(+) maps. Implications for in vivo B1(+) mapping at 3.0 T and 7.0 T are discussed

Nominal values of the initial excitation angle (<i>p</i>0), flip angle of each sub-pulse (α), total flip angle (<i>TotalFA</i>), <i>B₁</i>+ intensity, total duration of the RF-pulses, echo times (TE) and repetition times (TR) for the experiments performed in phantom and <i>in vivo</i>, at 3.0 T and 7.0 T, with methods A–E.

<p>Also the parameters for the comparison with the DAM are listed. The echo times are calculated relatively to the center of the first sub-pulse for each method.</p

Renaming the DSCR1/Adapt78 gene family as RCAN: regulators of calcineurin

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