Estimating Sink Parameters of Stochastic Functional-Structural Plant Models Using Organic Series-Continuous and Rhythmic Development

Functional-structural plant models (FSPMs) generally simulate plant development and growth at the level of individual organs (leaves, flowers, internodes, etc.). Parameters that are not directly measurable, such as the sink strength of organs, can be estimated inversely by fitting the weights of organs along an axis (organic series) with the corresponding model output. To accommodate intracanopy variability among individual plants, stochastic FSPMs have been built by introducing the randomness in plant development; this presents a challenge in comparing model output and experimental data in parameter estimation since the plant axis contains individual organs with different amounts and weights. To achieve model calibration, the interaction between plant development and growth is disentangled by first computing the occurrence probabilities of each potential site of phytomer, as defined in the developmental model (potential structure). On this basis, the mean organic series is computed analytically to fit the organ-level target data. This process is applied for plants with continuous and rhythmic development simulated with different development parameter sets. The results are verified by Monte-Carlo simulation. Calibration tests are performed both in silico and on real plants. The analytical organic series are obtained for both continuous and rhythmic cases, and they match well with the results from Monte-Carlo simulation, and vice versa. This fitting process works well for both the simulated and real data sets; thus, the proposed method can solve the source-sink functions of stochastic plant architectures through a simplified approach to plant sampling. This work presents a generic method for estimating the sink parameters of a stochastic FSPM using statistical organ-level data, and it provides a method for sampling stems. The current work breaks a bottleneck in the application of FSPMs to real plants, creating the opportunity for broad applications

An Algebra of Quantum Processes

We introduce an algebra qCCS of pure quantum processes in which no classical data is involved, communications by moving quantum states physically are allowed, and computations is modeled by super-operators. An operational semantics of qCCS is presented in terms of (non-probabilistic) labeled transition systems. Strong bisimulation between processes modeled in qCCS is defined, and its fundamental algebraic properties are established, including uniqueness of the solutions of recursive equations. To model sequential computation in qCCS, a reduction relation between processes is defined. By combining reduction relation and strong bisimulation we introduce the notion of strong reduction-bisimulation, which is a device for observing interaction of computation and communication in quantum systems. Finally, a notion of strong approximate bisimulation (equivalently, strong bisimulation distance) and its reduction counterpart are introduced. It is proved that both approximate bisimilarity and approximate reduction-bisimilarity are preserved by various constructors of quantum processes. This provides us with a formal tool for observing robustness of quantum processes against inaccuracy in the implementation of its elementary gates

Unconventional programming: non-programmable systems

Die Forschung aus dem Bereich der unkonventionellen und natürlichen Informationsverarbeitungssysteme verspricht kontrollierbare Rechenprozesse in ungewöhnlichen Medien zu realisieren, zum Beispiel auf der molekularen Ebene oder in Bakterienkolonien. Vielversprechende Eigenschaften dieser Systeme sind das nichtlineare Verhalten und der hohe Verknüpfungsgrad der beteiligten Komponenten in Analogie zu Neuronen im Gehirn. Da aber Programmierung meist auf Prinzipien wie Modularisierung, Kapselung und Vorhersagbarkeit beruht sind diese Systeme oft schwer- bzw. unprogrammierbar. Im Gegensatz zu vielen Arbeiten über unkonventionelle Rechensysteme soll in dieser Arbeit aber nicht hauptsächlich nach neuen rechnenden Systemen und Anwendungen dieser gesucht werden. Stattdessen konzentriert sich diese Dissertation auf unkonventionelle Programmieransätze, die sowohl für unkonventionelle Computer als auch für herkommliche digitale Rechner neue Perspektiven eröffnen sollen. Hauptsächlich in Bezug auf ein Modell künstlicher chemischer Neuronen werden Ansätze für unkonventionelle Programmierverfahren, basierend auf Evolutionären Algorithmen, Informationstheorie und Selbstorganisation bis hin zur Selbstassemblierung untersucht. Ein spezielles Augenmerk liegt dabei auf dem Problem der Symbolkodierung: Oft gibt es mehrere oder sogar unendlich viele Möglichkeiten, Informationen in den Zuständen eines komplexen dynamischen Systems zu kodieren. In Neuronalen Netzen gibt es unter anderem die Spikefrequenz aber auch Populationskodes. In Abhängigkeit von den weiteren Eigenschaften des Systems, beispielsweise von der Informationsverarbeitungsaufgabe und dem gewünschten Eingabe-Ausgabeverhalten dürften sich verschiedene Kodierungen als unterschiedlich nützlich erweisen. Daher werden hier Methoden betrachtet um die verschiedene Symbolkodierungmethoden zu evaluieren, zu analysieren und um nach neuen, geeigneten Kodierungen zu suchen.Unconventional and natural computing research offers controlled information modification processes in uncommon media, for example on the molecular scale or in bacteria colonies. Promising aspects of such systems are often the non-linear behavior and the high connectivity of the involved information processing components in analogy to neurons in the nervous system. Unfortunately, such properties make the system behavior hard to understand, hard to predict and thus also hard to program with common engineering principles like modularization and composition, leading to the term of non-programmable systems. In contrast to many unconventional computing works that are often focused on finding novel computing substrates and potential applications, unconventional programming approaches for such systems are the theme of this thesis: How can new programming concepts open up new perspectives for unconventional but hopefully also for traditional, digital computing systems? Mostly based on a model of artificial wet chemical neurons, different unconventional programming approaches from evolutionary algorithms, information theory, self-organization and self-assembly are explored. A particular emphasis is given on the problem of symbol encodings: Often there are multiple or even an unlimited number of possibilities to encode information in the phase space of dynamical systems, e.g. spike frequencies or population coding in neural networks. But different encodings will probably be differently useful, dependent on the system properties, the information transformation task and the desired connectivity to other systems. Hence methods are investigated that can evaluate, analyse as well as identify suitable symbol encoding schemes

A Practical Hardware Implementation of Systemic Computation

It is widely accepted that natural computation, such as brain computation, is far superior to typical computational approaches addressing tasks such as learning and parallel processing. As conventional silicon-based technologies are about to reach their physical limits, researchers have drawn inspiration from nature to found new computational paradigms. Such a newly-conceived paradigm is Systemic Computation (SC). SC is a bio-inspired model of computation. It incorporates natural characteristics and defines a massively parallel non-von Neumann computer architecture that can model natural systems efficiently. This thesis investigates the viability and utility of a Systemic Computation hardware implementation, since prior software-based approaches have proved inadequate in terms of performance and flexibility. This is achieved by addressing three main research challenges regarding the level of support for the natural properties of SC, the design of its implied architecture and methods to make the implementation practical and efficient. Various hardware-based approaches to Natural Computation are reviewed and their compatibility and suitability, with respect to the SC paradigm, is investigated. FPGAs are identified as the most appropriate implementation platform through critical evaluation and the first prototype Hardware Architecture of Systemic computation (HAoS) is presented. HAoS is a novel custom digital design, which takes advantage of the inbuilt parallelism of an FPGA and the highly efficient matching capability of a Ternary Content Addressable Memory. It provides basic processing capabilities in order to minimize time-demanding data transfers, while the optional use of a CPU provides high-level processing support. It is optimized and extended to a practical hardware platform accompanied by a software framework to provide an efficient SC programming solution. The suggested platform is evaluated using three bio-inspired models and analysis shows that it satisfies the research challenges and provides an effective solution in terms of efficiency versus flexibility trade-off