Disturbance and Input-Output Decoupling of Systems

The disturbance decoupling and the simultaneous disturbance and input–output decoupling problems for singular systems are considered in the context of the matrix fraction description (MFD) of the system. Solvability conditions are obtained in terms of the composite matrix of a column reduced MFD of the system, a characterisation of the fixed poles of both problems is given and it is shown that the remaining poles can be arbitrarily assigned

Unimodular equivalence and similarity for linear systems

The problem of finding the mapping between unimoduar transformations relating two minimal matrix fraction descriptions (MFDs) of a transfer function, and the similarity transformations relating the respective minimal state-space representations is considered. It is shown that the problem is equivalent to finding the relation of MFDs of the input-state transfer functions of the two systems. This relation turns out to be an equivalence relation involving the unimodular and the similarity matrices relating the MFDs and the state-space systems, respectively. A canonical form for MFDs under this equivalence relation is obtained and it is shown that it leads to a canonical state-space representation, via a realisation procedure

Unimodular Transformations and Canonical Forms for Singular Systems

The relationship between the unimodular matrices relating coprime and column reduced matrix fraction descriptions (MFD) of a nonproper transfer function, and the restricted system equivalence (r.s.e.) transformations relating the corresponding generalised state space realisations is considered. It is shown that the r.s.e and unimodular transformations can be directly obtained from each other by inspection. The r.s.e. transformations leading to the canonical form are derived from the unimodular transformations leading to the echelon canonical form of the composite matrix of the MFD of the system

Large bilateral adrenal metastases in non-small cell lung cancer

BACKGROUND: The adrenal gland is one of the common sites of metastasis from primary lung cancer. Adrenal metastases are usually unilateral however bilateral adrenal metastases are seen in 10% of all lung cancer patients; of these 2–3% occurs at the initial presentation of non-small cell lung cancer. Secondary tumors can disrupt the structure and function of the adrenal. This can lead to adrenal hemorrhage, which constitutes a life threatening hazard for the patient. CASE PRESENTATION: A 59-year-old male presented with persisting abdominal pain. His initial work-up revealed significant anemia, an invasive process in the right upper lobe of the lung and large masses of heterogeneous texture, with hemorrhagic and necrotic elements in both adrenal glands. A biopsy confirmed it to be a large-cell carcinoma of the lungs. The patient developed severe leukocytosis akin to the paraneoplastic syndrome and died suddenly five days after the administration of chemotherapy. CONCLUSION: Intratumoral hemorrhage is a rare but life threatening complication of adrenal metastases and should be treated as soon as it has been diagnosed. If adrenalectomy is not feasible, combination chemotherapy should be applied as in metastatic disease. For choosing the appropriate chemotherapeutic regimen it is important to accurately achieve the diagnosis

Systems and control problems in early systems design

This thesis is concerned with the evaluation of properties of early design models, the control structure selection and the representation and properties of composite system models. The work is motivated by the need to introduce a Systems and Control Theory based framework for early design stages of the overall system design of engineering processes, and in particular chemical processes, such as process synthesis and control structure selection. The overall spirit of the work is that engineering design is an evolutionary process, the different stages of which shape the structure of the resulting system models and precondition the potential for design at the next stage. The work identifies a number of key problems in the overall design, which are of a generic, systemic character, and then deals with working out solutions for such problems. The results contribute in the development of a framework for systems integration using as criteria and tools, those provided by Systems and Control Theory. The work aims to provide a control theoretic dimension to the rules and practices currently used in the specific application areas. The thesis contributes in the development of a Systems and Control conceptual and tools framework for integrated design of engineering processes by providing results in the following areas: - Specification of a number of generic problems in the field of integrated design and identification of relevant control theoretic concepts and tools. - Study of Model Orientation for linear implicit state-space models and definition of classes of oriented realisations. - Development of solutions to two problems of Structural Identification for uncertain early process models related to infinite zero structure and McMillan degree. - Development of a generic representation of composite systems that allows the study of transition from the aggregate to composite system properties, as a generalised Control Design and characterisation of some key system properties. -Specification of a framework for integrated Control Structure Selection and development of software for many approaches of the "interaction analysis" indicators. The results contribute in the area of development of the systems and control ideas for the problems of systems integration and early design. The work emphasises the strong links between Modelling, Selection of Control Structures and Control Structural methodologies

Algebraic and Geometric Methods and Problems for Implicit Linear Systems

This thesis investigates a number of problems of the implicit linear systems framework. First, the problem of realisations of nonproper transfer functions is considered. The main result obtained here is the generalisation of the realisation method from MFDs to the case of the nonproper transfer functions. The obtained realisations are singular systems. The method treats both finite and infinite frequency behaviour in a unified way and generalises the results related to the minimality of the realisation and coprimeness and column reducedness of the MFD. Furthermore, it displays transparently the relation between the extended MacMillan degree of the transfer function and the minimal realisation. The next problem considered is the problem of canonical forms of minimal singular systems under restricted system equivalence transformations. For systems with outputs a canonical form is obtained and it is shown that it is directly related to the echelon form of the composite matrix of an MFD of the transfer function of the system. This result is a direct generalisation of the results of Popov and Forney for strictly proper systems. The canonical form obtained is of Popov type and may be considered as a direct generalisation of the well known form for strictly proper systems. The second canonical form is for systems without outputs. A Popov type canonical form for a class of these systems is obtained. This class is that of systems with equal reachability indices. For both canonical forms, the sequence of the transformations yielding the canonical description is described in detail. In the general case of systems without outputs a semi canonical Popov type form is obtained. Another problem considered in the thesis is the problem of first order realisations of autoregressive equations within the external equivalence framework. An alternative to the existing methods is provided; in fact, the proposed method is simpler than the existing ones and allows the derivation of the realisation by inspection of the autoregressive equations. A generalisation of the observability indices is proposed for nonsquare descriptor systems and their connection to the autoregressive equations is established. The problem of model matching for implicit systems is considered next. This is a generalisation of the model matching problem for systems described by transfer functions. Here a controller is interconnected to the given plant such that the overall system has a desired external behaviour. The problem is studied within the framework of external and A-external (input-output) equivalence. Necessary as well as sufficient conditions for the solvability of the problem are derived and the equations of the controllers are found in a constructive way. The last problem considered here is the generalised dynamic cover problem of geometric theory i.e. the problem of finding the family of (A, B)-invariant subspaces covering a given subspace. This problem is formulated here by using the matrix pencil approach of the geometric theory. This approach allows the unification of the problem for state-space and nonsquare descriptor systems. An extension of the problem to the case of infinite spectrum spaces is also obtained. The solution of the above problems is reduced to the solution of appropriately defined systems of linear equations. Finally, an alternative method for the solution involving systems of multilinear equations is proposed using the mathematical tool of Groebner bases

Serous labyrinthitis as a manifestation of cat scratch disease: a case report

<p>Abstract</p> <p>Introduction</p> <p>Cat scratch disease is an infectious disease transmitted by young cats, in which the principal causative factor is <it>Bartonella henselae</it>. The typical course of cat scratch disease is usually benign and self-limited and requires only supportive therapy. However, cases lasting up to 2 years have been reported, and more serious complications may occur. Many manifestations of the disease have been reported by different medical disciplines.</p> <p>Case presentation</p> <p>A case of cat scratch disease in a 71-year-old Greek woman with an unusual clinical course is presented here. Serous otitis media was combined with rotational vertigo due to labyrinthitis. The invaded ear was ipsilateral to the inoculation site.</p> <p>Conclusion</p> <p>Cervicofacial lymphadenopathy has been demonstrated as the most common otolaryngologic manifestation of cat scratch disease. Manifestation in the middle and inner ear has, to the best of our knowledge, not been reported before. Our report presents a patient with cat scratch disease with clinical signs and symptoms in the middle and inner ear.</p