Mathematical modelling and optimal multivariable control of chemical processes

This work reports the developnent of a mathenatical model and distributed, multi variable computer-control for a pilot plant double-effect climbing-film evaporator. A distributed-parameter model of the plant has been developed and the time-domain model transformed into the Laplace domain. The model has been further transformed into an integral domain conforming to an algebraic ring of polynomials, to eliminate the transcendental terms which arise in the Laplace domain due to the distributed nature of the plant model. This has made possible the application of linear control theories to a set of linear-partial differential equations. The models obtained have well tracked the experimental results of the plant. A distributed-computer network has been interfaced with the plant to implement digital controllers in a hierarchical structure. A modern rnultivariable Wiener-Hopf controller has been applled to the plant model. The application has revealed a limitation condition that the plant matrix should be positive-definite along the infinite frequency axis. A new multi variable control theory has emerged fram this study, which avoids the above limitation. The controller has the structure of the modern Wiener-Hopf controller, but with a unique feature enabling a designer to specify the closed-loop poles in advance and to shape the sensitivity matrix as required. In this way, the method treats directly the interaction problems found in the chemical processes with good tracking and regulation performances. Though the ability of the analytical design methods to determine once and for all whether a given set of specifications can be met is one of its chief advantages over the conventional trial-and-error design procedures. However, one disadvantage that offsets to some degree the enormous advantages is the relatively complicated algebra that must be employed in working out all but the simplest problem. Mathematical algorithms and computer software have been developed to treat some of the mathematical operations defined over the integral domain, such as matrix fraction description, spectral factorization, the Bezout identity, and the general manipulation of polynomial matrices. Hence, the design problems of Wiener-Hopf type of controllers and other similar algebraic design methods can be easily solved.

Die Behandlung englischen Kulturgutes im Wiener fin de siècle:am Beispiel von Hugo von Hofmannsthal, Hermann Bahr und Peter Altenberg

This study explores the fascination which English culture represented in turn-of-the-century Vienna. The writers that are going to be discussed are the renowned Anglophile Hugo von Hofmannsthal, the more ambivalent Hermann Bahr and the idealizing, but Janus-faced Peter Altenberg. With the more widely known poet, prose writer and playwright, Hofmannsthal, individual aspects of his engagement with English culture have already been well researched; the same, however, cannot be said in the case of Hermann Bahr, whose extensive literary oeuvre has now largely been forgotten, and who has, instead, come to be valued as a prominent figure in the culture life of modernist Vienna, and Peter Altenberg, whose literary fame rests mainly on his prose poems and who, a legend in his life-time, has in recent years also increasingly attracted research interest as a phenomenon and ‘embodiment’ of the culture of his time: while their engagement with French literature, for example, has long received its due share of attention, their debt to English culture has, until now, been neglected. This thesis, therefore, sets out to explore Hofmannsthal’s, Bahr’s and Altenberg’s perception and portrayal of English civilization – ranging from English character and stereotypes, to what they saw as the principles of British society; it goes on to investigate the impulses they derive from Pre-Raphaelite art (Rossetti, Burne-Jones, Whistler) and the art and crafts-movement centred around William Morris, as well as their inspiration by the art criticism of John Ruskin and Walter Horatio Pater. In English literature one of the focal points will be their reading and evaluation of aestheticism as it was reflected in the life and writings of the Dubliner Oscar Wilde, who was perceived, by these Austrian authors, as a predominant figure of London’s cultural life. Similarly, they regarded his compatriot George Bernard Shaw as a key player in turn-of-the-century English (and European) culture. Hermann Bhar largely identified with him. Hofmannsthal, on the other hand, while having some reservations, acknowledged his importance and achievements, whereas Peter Altenberg saw in Shaw a model to reassure him, as his writings were becoming more openly didactic and even more miniaturistic than they had already been. He turned to Shaw, too, to explain and justify his new goal of making his texts more intelligent to a wider circle of readers.

Binary sparse nonnegative matrix factorization

This paper presents a fast part-based subspace selection algorithm, termed the binary sparse nonnegative matrix factorization (B-SNMF). Both the training process and the testing process of B-SNMF are much faster than those of binary principal component analysis (B-PCA). Besides, B-SNMF is more robust to occlusions in images. Experimental results on face images demonstrate the effectiveness and the efficiency of the proposed B-SNMF.

Analysis of Wiener-Hammerstein equalizer for downlink LTE system

We propose a Wiener-Hammerstein (W-H) channel estimation algorithm for Long-Term Evolution (LTE) systems. The LTE standard provides known data as pilot symbols and exploits them through coherent detection to improve system performance. These drivers are placed in a hybrid way to cover up both time and frequency domain. Our aim is to adapt the W-H equalizer (W-H/E) to LTE standard for compensation of both linear and nonlinear effects induced by power amplifiers and multipath channels. We evaluate the performance of the W-H/E for a Downlink LTE system in terms of BLER, EVM and Throughput versus SNR. Afterwards, we compare the results with a traditional Least-Mean Square (LMS) equalizer. It is shown that W-H/E can significantly reduce both linear and nonlinear distortions compared to LMS and improve LTE Downlink system performance.