Th. 3e cycle--Génie géol. et minier--Nancy--I.N.P.L., 1980.

Th. doct.-ing.--Nancy, I.N.P.L., 1981.

From Introduction: The balance between practical and theoretic components in the total submission bears relation to the title of this essay where aesthetic advantages are largely theoretical and where technical advantages refer mainly to the practical component. The historical significance of this structure is to be found in the earliest treatises on painting, Cenninni's treatment of painting as a purely practical matter is in accord with medieval tradition. His recipes are aligned according to the various individual techniques, tempera painting being the most significant to this essay. Practical recipes are interspersed with directions for the representation of various pictorial themes, and in the resultant conglomeration, the subdivisions are discernible only as basic premises. In contrast to him, the Renaissance authors beginning with Alberti make a significant innovation in that they divide their material into a theoretical and a practical part . The inter-relationship of practical and theoretical - aesthetic and technical aspects are un-avoidable when it comes down to realities. This is clearly illustrated in the notes of Leonardo da Vinci. Plans for the organization of the treatise are vaguely formulated .

This project concerns the development of electrical impedance tomography towards the production of complex impedance images. The prime intention was to investigate the feasibility of developing suitable instrumentation; but not clinical applications. It was aimed to develop techniques for the performance evaluation of data collection systems. To achieve this it was necessary to design and develop a multi· current source type impedance tomography system, to act as a platform for the current study and for future work. The system developed is capable of producing conductivity and permittivity images. It employs microprocessor based data collection electronics, providing portability between a range of possible host computers. The development of the system included a study of constant amplitude current source circuits leading to the design and employment of a novel circuit. In order to aid system testing, a surface mount technology resistor-mesh test object was produced. This has been adopted by the EEC Concerted Action on Impedance Tomography (CAIT) programme as the first standard test object. A computer model of the phantom was produced using the industry standard ASTEC3 circuit simulation package. This development allows the theoretical performance of any system topology, at any level of detail, to be established. The imaging system has been used to produce images from test objects, as well as forearm and lung images on humans. Whilst the conductivity images produced were good, the permittivity in-vivo images were noisy, despite good permittivity images from test objects. A study of the relative merits of multiple and single stimulus type systems was carried out as a result of the discrepancies in the in-vivo and test object images. This study involved a comparison of the author's system with that of Griffiths at the University Hospital of Wales. The results showed that the multi current source type system, whilst able to reduce stray capacitance, creates other more significant errors due to circuit matching; future development in semiconductor device technology may help to overcome this difficulty. It was identified that contact impedances together with the effective capacitance between the measurement electrode pairs in four-electrode systems reduces the measurability of changes in phase. A number of benchmarking indices were developed and implemented, both for system characterisation and for practical/theoretical design comparisons.

Nowadays, computers play an indispensable role in the determination of metal-ligand formation constants and in their application to various situations of analytical, industrial or biological interest. The development of programs and simulation techniques to meet some current problems in bioinorganic chemistry constitutes the broad objective of the present research. Consideration is given to the thermodynamic calculation of complex species concentrations in biological fluids. New methods of solving the mathematical relationships for metal-ligand solution equilibria, particularly in the simulation of large multicomponent systems, are investigated. The ways in which computer simulations are involved in the determination of formation constants are discussed. Principles are developed and applied to problems concerning (i) the calibration of glass electrodes and (ii) the choice of complex species to describe metal-ligand systems under experimental investigation. The function of transition elements in biological systems is briefly reviewed. Emphasis is given to the significance of low-molecular-weight complexes and how a knowledge of their in vivo behaviour can affect bioinorganic drug design. The relationship between copper and rheumatoid arthritis and the importance of equilibria in the regulation of iron metabolism are treated in some detail. New simulation techniques are developed for blood plasma. The results successfully rationalise many bioinorganic phenomena. In particular, the relative ability of a series of chelating agents to compete with proteins for metal ions in plasma is correlated with the urinary excretion of trace elements that they cause. Further simulations extend the approach to other biofluids and to medical solutions intended for intravenous infusion.

There is considerable evidence indicating an association between aflatoxin ingestion and liver cancer in humans. The development of methods that would permit the monitoring of aflatoxin exposure in individuals would provide useful information in assessing human risk from this toxin. In this study, an ELISA technique, using a polyclonal antibody raised against aflatoxin B1 in the rabbit, was developed for monitoring the levels of aflatoxin excreted in human urine samples. Urine could not be used directly in the assay because high blanks were observed from the presence of some aflatoxin-like substances. A 'clean-up' procedure using Sep-Pak C[13] cartridges and immunoaffinity columns was developed. The methods were validated using [3]H-AFB[1] in both buffer and presumed uncontaminated human urine samples from Europeans. As AFB[1] itself is unlikely to be found in human samples, urine from marmoset monkeys treated with [14]C-AFB1 were also used in the validation processes as they are likely to contain a spectrum of aflatoxin metabolites similar to those in human urine. The levels of AFB[1]. equivalents were monitored by both radioactive counting and ELISA. The radioactive measurements demonstrated that the overall recovery of the ELISA method was approximately 50%. The failure to detect all of the aflatoxin contamination in the urine may be due to the inability of the antibody to detect most of the polar aflatoxin metabolites. When the ELISA method was used in monitoring aflatoxin excreted in patients with or without liver disease from Thailand, a range of aflatoxin levels in the urine samples were obtained. Since in Thailand, liver fluke infection, caused by Opisthorchis viverrini is a serious health problem in the area where there is high contamination with aflatoxin in food and a high incidence of liver cancer, the interaction between liver fluke infection and aflatoxin ingestion was also studied using hamster as an animal model. The results indicated that liver fluke infection may alter the pattern of aflatoxin metabolites excreted in hamster urine, which in turn could affect the results obtained from the ELISA. Measurements by the ELISA method of aflatoxin excreted in urine samples from Thai vegetarians; who are a population at high risk of exposure to aflatoxin suggested that this group of people excreted higher levels of aflatoxin, but a further study with a greater number of subjects would be necessary to confirm this finding.

Abstraction in computer programming provides a means of reducing complexity by emphasising the significant information (program behaviour) whilst suppressing the immaterial (program implementation). This aids program construction, improves reliability and maintainability, and eases the application of formal correctness proofs. The importance of data abstraction in the specification, design and implementation of large systems raises the question as to whether such methods may be applied in the context of programming languages designed before the widespread use of abstraction techniques. The program structuring facilities available in FORTRAN 77 support a form of encapsulation for simple data structures. In light of this mechanism provided by the language, state-based specification was found to be most appropriate. A specification technique incorporating object-oriented techniques is particularly suitable and allows a library of object classes to be specified and then implemented in sequential FORTRAN 77. Refinement extends the object classes so as to provide the commonly occurring generators for use in iterative constructs. Therefore, the advantages of data abstraction methods may be obtained in an early procedural language such as FORTRAN 77. Data abstraction provides data independence : a change in the representation for a particular class of objects affects only the code that implements the associated operations. This allows parallel implementations to be considered, without changes to the original specification or to any user-code. The provision of such parallel data structures is required for the migration of sequential systems onto parallel distributed memory architectures. As an illustration of this approach a general 2P2-2P (for integer P≥3) search tree utilising a pipeline of processors in a distributed memory architecture is shown to provide a means of implementing the object classes. Variations in both the number of processors allocated to the pipeline and the value of P allows the optimal search structure for a given architecture to be determined. These structures are highly efficient leading to improvements in both throughput and response time as processors are added to the array. An efficient parallel implementation of object classes is therefore achieved within the tight interface provided by abstraction.

No description available.

L'objectif de cette thèse consiste à étudier un dispositif d'imagerie passive en gamme millimétrique pour la détection d'objets faiblement dissimulés en vue d'applications pour la sécurité des personnes. En s'abstenant d'éléments émetteurs nous assurons l'inoffensivité du dispositif. La détection s'effectue donc par radiométrie dans une bande de fréquences autour de 140 GHz afin de profiter du rayonnement important de la brillance spectrale des matériaux. Pour obtenir une image précise de la scène observée un unique récepteur n'est pas suffisant. Nous avons opté pour un dispositif interférométrique à haute résolution composé de plusieurs récepteurs radiométriques à détection I/Q (en phase et en quadrature). La mesure est ainsi basée sur le principe de synthèse d'ouverture permettant une résolution spatiale importante tout en conservant des antennes intégrables afin de limiter l'encombrement des récepteurs. Dans cette bande de fréquence, la conception des récepteurs nécessite la réalisation de circuits MMIC en technologie métamorphique HEMT 70 nm sur AsGa. Leurs performances permettent d'étudier précisément par simulation le comportement des récepteurs, plus particulièrement les erreurs ajoutées par ces derniers dans le but de les modéliser pour faciliter la reconstruction d'image. L'architecture de l'interféromètre permet de diminuer le nombre de récepteurs employés par rapport à la résolution de l'image reconstruite. La reconstruction d'image est obtenue par la solution en bande limitée du problème inverse. Ces travaux permettent de déterminer les caractéristiques du système en fonction des performances associées aux applications envisagées / The aim of this thesis is to study a passive imaging system in the millimeter range for the remote sensing of lower concealed objects applied to human security. The inoffensive character of the device is ensured by the lack of active emitter devices. The detection is a radiometric remote sensing within a frequency band centered around 140 GHz in order to benefit from the important radiation of the material spectral brightness. To get a clear picture of the observed scene, a single receiver is not enough. We decided to develop a high-resolution interferometric composed of several radiometric I / Q (in-phase and quadrature) receptors. The measurement is based on the principle of synthetic aperture allowing an important spatial resolution while maintaining integrated antennas in order to limit the size of the receivers. In this frequency band, the design of receivers requires the realization of MMIC devices, using the metamorphic HEMT 70 nm on GaAs technology from OMMIC. Their performance allow a precise study of the simulated behavior of receivers, mainly the added errors, in order to facilitate the model for image reconstruction. The architecture of the interferometer reduces the number of receivers used with respect to the resolution of the reconstructed image. The image reconstruction is obtained by band-limited solution of the inverse problem. This work identifies the characteristics of the system in function of the performances associated with applications.

No description available.