Compositional circuit design with asynchronous concepts

PhD ThesisSynchronous circuits are pervasive in modern digital systems, such as smart-phones, wearable devices and computers. Synchronous circuits are controlled by a global clock signal, which greatly simplifies their design but is also a limitation in some applications. Asynchronous circuits are a logical alternative: they do not use a global clock to synchronise their components. Instead, every component reacts to input events at the rate they occur. Asynchronous circuits are not widely adopted by industry, because they are often harder to design and require more sophisticated tools and formal models. Signal Transition Graphs (STGs) is a well-studied formal model for the specification, verification and synthesis of asynchronous circuits with state-of-the-art tool support. STGs use a graphical notation where vertices and arcs specify the operation of an asynchronous circuit. These graphical specifications can be difficult to describe compositionally, and provide little reusability of useful sections of a graph. In this thesis we present Asynchronous Concepts, a new design methodology for asynchronous circuit design. A concept is a self-contained description of a circuit requirement, which is composable with any other concept, allowing compositional specification of large asynchronous circuits. Concepts can be shared, reused and extended by users, promoting the reuse of behaviours within single or multiple specifications. Asynchronous Concepts can be translated to STGs to benefit from the existing theory and tools developed by the asynchronous circuits community. Plato is a software tool developed for Asynchronous Concepts that supports the presented design methodology, and provides automated methods for translation to STGs. The design flow which utilises Asynchronous Concepts is automated using Plato and the open-source toolsuite Workcraft, which can use the translated STGs in verification and synthesis using integrated tools. The proposed language, the design flow, and the supporting tools are evaluated on real-world case studies

Self-Evaluation Applied Mathematics 2003-2008 University of Twente

This report contains the self-study for the research assessment of the Department of Applied Mathematics (AM) of the Faculty of Electrical Engineering, Mathematics and Computer Science (EEMCS) at the University of Twente (UT). The report provides the information for the Research Assessment Committee for Applied Mathematics, dealing with mathematical sciences at the three universities of technology in the Netherlands. It describes the state of affairs pertaining to the period 1 January 2003 to 31 December 2008

Engineering Education and Research Using MATLAB

MATLAB is a software package used primarily in the field of engineering for signal processing, numerical data analysis, modeling, programming, simulation, and computer graphic visualization. In the last few years, it has become widely accepted as an efficient tool, and, therefore, its use has significantly increased in scientific communities and academic institutions. This book consists of 20 chapters presenting research works using MATLAB tools. Chapters include techniques for programming and developing Graphical User Interfaces (GUIs), dynamic systems, electric machines, signal and image processing, power electronics, mixed signal circuits, genetic programming, digital watermarking, control systems, time-series regression modeling, and artificial neural networks

Industrial and Technological Applications of Power Electronics Systems

The Special Issue "Industrial and Technological Applications of Power Electronics Systems" focuses on: - new strategies of control for electric machines, including sensorless control and fault diagnosis; - existing and emerging industrial applications of GaN and SiC-based converters; - modern methods for electromagnetic compatibility. The book covers topics such as control systems, fault diagnosis, converters, inverters, and electromagnetic interference in power electronics systems. The Special Issue includes 19 scientific papers by industry experts and worldwide professors in the area of electrical engineering

Analysis and design of switched-capacitor DC-DC converters with discrete event models

Ph. D. Thesis.Switched-capacitor DC-DC converters (SCDDCs) play a critical role in low power integrated systems. The analysis and design processes of an SCDDC impact the performance and power efficiency of the whole system. Conventionally, researchers carry out the analysis and design processes by viewing SCDDCs as analogue circuits. Analogue attributes of an SCDDC, such as the charge flow current or the equivalent output impedance, have been studied in considerable detail for performance enhancement. However, in most existing work, less attention is paid to the analysis of discrete events (e.g. digital signal transitions) and the relationships between discrete events in SCDDCs. These discrete events and the relationships between discrete events also affect the performance of SCDDCs. Certain negative effects of SCDDCs such as leakage current are introduced by unhealthy discrete states. For example, MOS devices in an SCDDC could conduct undesirably under certain combinations of signals, resulting in reversion losses (a type of leakage in SCDDCs). However, existing work only use verbal reasoning and waveform descriptions when studying these discrete events, which may cause confusion and result in an informal design process consisting of intuitive design and backed up merely by validation based on natural language discussions and simulations. There is therefore a need for formalised methods to describe and analyse these discrete events which may facilitate systematic design techniques. This thesis presents a new method of analysing and designing SCDDCs using discrete event models. Discrete event models such as Petri nets and Signal Transition Graphs (STGs) are commonly used in asynchronous circuits to formally describe and analyse the relationships between discrete transitions. Modelling SCDDCs with discrete event models provides a formal way to describe the relations between discrete transitions in SCDDCs. These discrete event models can be used for analysis, verification and even design guidance for SCDDC design. The rich set of existing analysis methods and tools for discrete event models could be applied to SCDDCs, potentially improving the analysis and design flow for them. Moreover, since Petri nets and STGs are generally used to analyse and design asynchronous circuits, modelling and designing SCDDCs with STG models may additionally facilitate the incorporation of positive features of asynchronous circuits in SCDDCs (e.g. no clock skew). In this thesis, the relations between discrete events in SCDDCs are formally described with SC-STG (an extended STG targeting multi-voltage systems, to which SCDDCs belong), which avoids the potential confusion due to natural language and waveform descriptions. Then the concurrency and causality relations described in SC-STG model are extended to Petri nets, with which the presence of reversion losses can be formally determined and verified. Finally, based on the STG and Petri net models, a new design method for reversion-loss-free SCDDCs is proposed. In SCDDCs designed with the new method, reversion losses are entirely removed by introducing asynchronous controls, synthesised with the help of a software synthesis toolkit “Workcraft”. To demonstrate the analysis capabilities of the method, several cross-coupled voltage doublers (a type of SCDDC) are analysed and studied with discrete event models as examples in this thesis. To demonstrate the design capabilities of the method, a new reversion-loss-free cross-coupled voltage doubler is designed. The cross-coupled voltage doubler is widely used in low power integrated systems such as flash memories, LCD drivers and wireless energy harvesting systems. The proposed modelling method is potentially used in both research and industrial area of those applications for a formal and high-efficiency design proces

Data driven modelling of crystalliser particle size distribution

Abstract. The aim of the thesis was to gain knowledge of the crystallisation process and to get insight on the process variables controlling it. To reach this aim static models were identified, and their performance was analysed. Measurement data from the crystallisation process was used as inputs to the developed model while the output was the D50 value of the particle size distribution. The measurement data was averaged for every 15 minutes and pre-processed by removing outliers and filtering. Two datasets were collected containing 21 input variables. Training data included measurements from a three-and-a-half-day period and test data from a two- and-a-half-day period. LASSO algorithm was used for input variable selection. The selected variable subsets contained 21, 19, 12 and 3 variables. Neural network models containing 15, 25, 35 or 40 neurons were trained and tested using these input variable subsets. Neural network models did not perform well with test data, as their mean absolute percentage error (MAPE) was over 20%. The models containing 12 input variables and 25 or 35 neurons or 19 input variables and 35 neurons performed the best with test data. MeSO4 and NH3 densities and crystalliser pH were the most important variables for modelling, according to the LASSO algorithm.Kiteyttimen partikkelikokojakauman datapohjainen mallinnus. Tiivistelmä. Työn tavoitteena oli lisätä prosessitietämystä kiteytysprosessista sekä saada lisätietoa reaktioon vaikuttavista muuttujista. Tavoitteeseen päästiin kiteytysprosess ista muodostettua staattista mallia analysoimalla. Prosessin mittainstrumenteista saatu mittausdata toimi mallin tulomuuttujina ja näytteiden analysoinnilla saadun partikkelikokojakauman D50-arvo lähtömuuttujana. Mittausdata keskiarvoistettiin 15 minuutin intervalleihin datan esikäsittelyä varten, jolloin datasta poistettiin poikkeamat sekä data suodatettiin. Prosessista kerättiin kaksi mittausaineistoa, jotka molemmat pitivät sisällään 21 muuttujaa. Opetusdata sisälsi mittausdataa 3,5 päivän tuotantojaksolta ja testidata 2,5 päivän tuotantojaksolta. LASSO- algoritmia käytettiin muuttujien valintaan. Valitut muuttujajoukot sisälsivät 21, 19, 12 ja 3 muuttujaa. Jokaisesta muuttujajoukosta luotiin neljä neuroverkkomallia. Neuroverkkojen neuroneiden määrät olivat 15, 25, 35 ja 40. Neuroverkkomallit suoriutuvat testidatalla kaiken kaikkiaan huonosti ja niiden suhteellinen virhe oli yli 20 %. Parhaiten testidatalla suoriutuvat neuroverkkomallit, joiden käyttämä muuttujajoukko sisälsi 12 muuttujaa ja joiden piilokerrokset sisälsivät 25 ja 35 neuronia sekä neuroverkko, joka käytti muuttujajoukossaan 19 muuttujaa ja jonka piilokerros sisälsi 35 neuronia. LASSO-algoritmin mukaan kolme tärkeintä muuttujaa olivat MeSO4- ja NH3-tiheydet sekä kiteyttimen pH

Gas-consuming triphasic gas-liquid-liquid reactions in segmented slug flow

The chemical industry in Europe is transforming. Diversifying raw materials, an increased circular economy and a growing market of specialty chemicals require flexible and fast process development. Small-scale continuous reactors can contribute to these requirements. In particular, triphasic gas-liquid-liquid slug flows can perform complex multiphase systems at a laboratory scale. This work investigates strategies to counteract a gas shortage in gas-consuming reactions in such capillaries. On the one hand, gas permeation through the polymer capillary is investigated, and its influence on an existing slug flow is studied. On the other hand, individual gas bubbles are integrated into the slug flow using valves and an electrolysis cell. Both methods preserve the advantageous slug flow - however, they have advantages and disadvantages depending on the reaction applied. Moreover, they can be used in a scale-up of capillary reactors, contrary to established methods. For success in scale-up, inexpensive and robust sensors are necessary in addition to gas-feeding methods. For this purpose, non-invasive optoelectric sensors are developed for triphasic slug flows, which can detect the flow (velocity, phase ratios, segment lengths), but also determine local concentrations. Both light refraction and light absorption are exploited. Concentration sensors are used to study the homogeneously catalyzed hydrogenation of a dye to a colorless form. A change in hydrodynamic parameters had only minor effects compared to chemical parameters. However, the reaction was significantly intensified compared to a stirred tank reactor. Finally, selective fat hydrogenation in a triphasic slug flow is investigated. A suitable solvent selection can counteract unfavorable solid formation. The monounsaturated fatty acid could be selectively obtained from sunflower oil with a high content of polyunsaturated fatty acids.Die chemische Industrie in Europa steht vor einem Wandel, eine Diversifizierung der Rohstoffe, eine vermehrte Kreiswirtschaft und ein wachsender Anteil an Spezialchemikalien erfordern eine flexible und schnelle Prozessentwicklung. Kleinskalige kontinuierliche Reaktoren können dazu beitragen. Insbesondere dreiphasige gas-flüssig-flüssig Pfropfenströmungen können komplexe Mehrphasensysteme im Labormaßstab gut abbilden. Diese Arbeit untersucht Strategien, wie in gaskonsumierenden Reaktionen in solchen Kapillarreaktoren einem Mangel an Reaktionsgas entgegengewirkt werden kann. Zum einen wird die Gaspermeation durch die Polymerkapillare untersucht und deren Einfluss auf eine bestehende Pfropfenströmung untersucht. Zum anderen wird gezielt mit Ventilen und einer Elektrolysezelle einzelne Gasblasen in die Pfropfenströmung integriert. Beiden Methoden erhalten die vorteilhafte Pfropfenströmung - sie haben allerdings Vor- und Nachteile je nach angewandter Reaktion. Sie lassen sich beide, entgegen etablierter Verfahren, in einer Maßstabsvergrößerung der Kapillarreaktoren verwenden. Für das Gelingen einer Maßstabsvergrößerung sind neben Gasnachspeisungsmethoden, günstige und robuste Sensoren notwendig. Dafür werden für die dreiphasigen Pfropfenströmungen nicht-invasive optoelektrische Sensoren entwickelt, die sowohl die Strömung (Geschwindigkeit, Phasenverhältnisse, Segmentlängen) detektieren, aber auch lokale Konzentrationen bestimmen können. Dabei werden sowohl die Lichtbrechung, als auch Lichtabsorption ausgenutzt. Konzentrationssensoren werden verwendet, um eine homogenkatalysierte Hydrierung eines Farbstoffs zu einer farblosen Form zu untersuchen. Eine Veränderung der hydrodynamischen Parameter hatte im Vergleich zu chemischen Parametern nur geringfügige Einflüsse. Allerdings konnte die Reaktion im Vergleich zu einem Rührkesselreaktor stark intensiviert werden. Abschließend wird die selektive Fetthydrierung in einer dreiphasigen Pfropfenströmung untersucht. Einer ungünstigen Feststoffablagerung kann durch eine geeignete Lösungsmittelwahl entgegengewirkt werden. Ausgehend von Sonnenblumenöl mit einem hohen Anteil an mehrfach ungesättigten Fettsäuren konnte selektiv die einfach ungesättigte Fettsäure umgesetzt werden

Sliding Mode Control

The main objective of this monograph is to present a broad range of well worked out, recent application studies as well as theoretical contributions in the field of sliding mode control system analysis and design. The contributions presented here include new theoretical developments as well as successful applications of variable structure controllers primarily in the field of power electronics, electric drives and motion steering systems. They enrich the current state of the art, and motivate and encourage new ideas and solutions in the sliding mode control area