Dissertations / Theses on the topic 'Ant'

The main objective of this study was to examine the abundance and diversity of ants in suburban sites following vegetation removal or modification for development. This research examines the capacity of suburban sites to support ant diversity, which is dependent on the site characteristics and their surrounding environment. The study focused on 29 suburban garden and 3 suburban reserve sites on the Gold Coast, Queensland, Australia. This region, through continuing land development, undergoes ongoing habitat disturbance and modification. Ground-dwelling ants were collected by pitfall trapping in study sites over three summers between 1997 and 1999. In total, 28,512 ants from 60 species in 31 genera were collected. Garden sites that maintain vegetation structural diversity were found to be most similar to reserve sites in terms of ant community composition. These sites were highest in ant richness and diversity and contained particularly high proportions of specialized ant species. Sites in close proximity to remnants of native vegetation contained higher species diversity and a greater proportion of specialized ant species. The introduced tramp ant, Pheidole megacephala was found in 28 of the 32 sites and was found to significantly reduce ant species richness and diversity and displace the dominant ant Iridomyrmex sp. 1 in suburban environments. This ant poses a serious threat to the recovery of a diverse ant fauna to suburban environments. Ant community composition was shown to vary significantly among suburban sites. The ant functional groups commonly found in disturbed sites were abundant in open sites with little canopy cover in this study. Sites that provided vegetation structural diversity and areas of closed canopy supported similar functional groups to natural vegetation remnants. These results indicate that ant communities in suburban environments respond to disturbance in a similar manner to ant communities in tropical forests and rainforests. The dominance by functional groups and presence of specialized species may therefore be used as an indicator of disturbance and the restoration of suitable habitat in suburban sites. The presence of specialized species of ants in suburban garden sites and their clear preference for particular site characteristics indicate that these species utilize resources available in the suburban matrix. These results indicate that residential suburban sites are of value in the enhancement of ant diversity in fragmented landscapes and that they may provide supportive habitat to, and act as corridors between, vegetation fragments. In order to preserve biodiversity within suburban environments, landowners should be advised to retain as much existing vegetation within a site as possible. Clearing should be limited to that necessary to allow construction of dwellings and for safety. In addition, landowners should be encouraged to establish or maintain structurally diverse vegetation layers within sites in order to provide diverse microenvironments for fauna habitat.

The purpose of this project is to create a light weight robotic version of an ant that can withstand great forces, trying to come close to the ant’s lifting technique as much as possible. This idea was chosen with inspiration from nature, especially from the obscure forces of an ant. These insects are proven to be able to lift and carry heavy loads, up to a thousand times their body weight. Various lifting technologies are used by several facilities today and therefore there is a need for improvements in this field. By trying to come close to an ant’s appearance and mimic certain ant movements, a hexapod was designed over a period of four months. The tests made in this project were divided into three categories; stability, lifting and gripping ability. The best balance was achieved by placing the legs’ contact points on the ground as far away from each other as possible. In total the robot ant could lift about 1.02 times its own weight and bear 3.01 times its own weight on the thorax.
Målet med projektet är att konstruera en lågvikts robotmyra som kan uthärda stora krafter och härma myrors rörelse vid lyft så mycket som möjligt. Projektidén valdes med inspiration från naturen, speciellt från de otroliga krafter hos en myra. Myror har bevisats kunna lyfta och bära tunga laster eller mer exakt tusen gånger sin egen vikt. Olika lyfttekniker används av flera faciliteter idag och därmed finns det behov av förbättringar i detta område. Genom att efterlikna en myras utseende och härma dess rörelser designades en sexfoting under en period på fyra månader. Testerna delades in i tre olika kategorier; stabilitet, lyft- och greppförmåga. Den bästa balansen uppnåddes då benens kontaktpunkter med marken placerades så långt ifrån varandra som möjligt. Totalt klarade robotmyran att lyfta 1.02 gånger sin egen vikt och bära 3.01 gånger egna vikten på ryggen.

Background: Myrmecia pilosula (the jack jumper ant, JJA) is the principal cause of ant venom anaphylaxis in Australia. Whereas honeybee and wasp venom allergy can be treated by venom immunotherapy (VIT), no such treatment is available for ant sting allergy. In addition, information on the natural history of JJA sting allergy is required to identify those most likely to benefit from immunotherapy. The main objectives of this research were to establish: (i) the prevalence, natural history and determinants of reaction severity for JJA allergy, and; (ii) the efficacy and tolerability of JJA VIT. Methods: A search of the Royal Hobart Hospital (RHH) forensic register, a random telephone survey, and a review of emergency department (ED) presentations were performed. Three hundred eighty-eight JJA allergic volunteers were assessed, including serum venom-specific IgE RAST, and then followed up for accidental stings over a 4-year period. Finally, a randomised double-blind, placebo-controlled, crossover trial of JJA VIT was performed. Laboratory parameters measured during the trial were; leukocyte stimulation index (SI), IL-4 production, IgE RAST, histamine release test (HRT), leukotriene release test (LRT) and basophil activation test (BAT). Intradermal venom skin testing (VST) was also performed at trial entry. Findings: The prevalence of JJA sting allergy was 2.7% in the Tasmanian population, compared to 1.4% for honeybee. People aged 35 or older had a greater risk of both sting allergy and hypotensive reactions. Four deaths were identified, all in adults with significant comorbidities. During follow-up, 79 (70%) of 113 accidental jack jumper stings caused systemic reactions. Only prior worst reaction severity predicted the severity of follow-up reactions, with the majority of people experiencing similar or less severe reactions when stung again. Sixty-eight otherwise healthy JJA allergic adult volunteers were enrolled in the clinical trial. Systemic reactions to therapy were recorded in 34% during VIT. Objectively defined systemic reactions to sting challenges arose in 1/35 after VIT (mild self-limiting urticaria only) versus 21/29 in the placebo group. Treatment with oxygen, intravenous adrenaline infusion and volume resuscitation was effective and well tolerated. Hypotension was always accompanied by a relative bradycardia, which was severe and treated with atropine in two patients. In the placebo group, only VST and HRT were predictive of sting challenge results. Although IgE RAST, leukocyte SI and IL-4 production, LRT and BAT all correlated well with VST, they did not predict sting challenge outcome. After successful VIT, venom-induced leukocyte IL-4 production tended to fall, whereas IgE RAST increased and a natural decline in HRT reactivity was reversed. Interpretation: VIT is highly effective in prevention of JJA sting anaphylaxis and is likely to be of most benefit to people with a history of severe systemic reactions, which usually occur in people aged over 35. Neurocardiogenic mechanisms &/or direct cardiac effects may be important factors in some anaphylaxis deaths. Systemic reactions to immunotherapy are common and require immediate access to resuscitation facilities. The HRT warrants further investigation as a test for selecting those most likely to benefit from VIT. None of the tests evaluated appear to be reliable markers of successful VIT.

The main objective of this study was to examine the abundance and diversity of ants in suburban sites following vegetation removal or modification for development. This research examines the capacity of suburban sites to support ant diversity, which is dependent on the site characteristics and their surrounding environment. The study focused on 29 suburban garden and 3 suburban reserve sites on the Gold Coast, Queensland, Australia. This region, through continuing land development, undergoes ongoing habitat disturbance and modification. Ground-dwelling ants were collected by pitfall trapping in study sites over three summers between 1997 and 1999. In total, 28,512 ants from 60 species in 31 genera were collected. Garden sites that maintain vegetation structural diversity were found to be most similar to reserve sites in terms of ant community composition. These sites were highest in ant richness and diversity and contained particularly high proportions of specialized ant species. Sites in close proximity to remnants of native vegetation contained higher species diversity and a greater proportion of specialized ant species. The introduced tramp ant, Pheidole megacephala was found in 28 of the 32 sites and was found to significantly reduce ant species richness and diversity and displace the dominant ant Iridomyrmex sp. 1 in suburban environments. This ant poses a serious threat to the recovery of a diverse ant fauna to suburban environments. Ant community composition was shown to vary significantly among suburban sites. The ant functional groups commonly found in disturbed sites were abundant in open sites with little canopy cover in this study. Sites that provided vegetation structural diversity and areas of closed canopy supported similar functional groups to natural vegetation remnants. These results indicate that ant communities in suburban environments respond to disturbance in a similar manner to ant communities in tropical forests and rainforests. The dominance by functional groups and presence of specialized species may therefore be used as an indicator of disturbance and the restoration of suitable habitat in suburban sites. The presence of specialized species of ants in suburban garden sites and their clear preference for particular site characteristics indicate that these species utilize resources available in the suburban matrix. These results indicate that residential suburban sites are of value in the enhancement of ant diversity in fragmented landscapes and that they may provide supportive habitat to, and act as corridors between, vegetation fragments. In order to preserve biodiversity within suburban environments, landowners should be advised to retain as much existing vegetation within a site as possible. Clearing should be limited to that necessary to allow construction of dwellings and for safety. In addition, landowners should be encouraged to establish or maintain structurally diverse vegetation layers within sites in order to provide diverse microenvironments for fauna habitat.
Thesis (Masters)
Master of Philosophy (MPhil)
School of Environmental and Applied Science
Full Text

The aim of this work is to investigate Ant Colony Algorithm for the traveling salesman problem (TSP). Ants of the artificial colony are able to generate successively shorter feasible tours by using information accumulated in the form of a pheromone trail deposited on the edges of the TSP graph. This paper is based on the ideas of ant colony algorithm and analysis the main parameters of the ant colony algorithm. Experimental results for solving TSP problems with ant colony algorithm show great effectiveness.

Traffic signal control is an effective way to improve the efficiency of traffic networks and reduce users’ delays. Ant Colony Optimization (ACO) is a metaheuristic based on the behavior of ant colonies searching for food. ACO has successfully been used to solve many NP-hard combinatorial optimization problems and its stochastic and decentralized nature fits well with traffic flow networks. This thesis investigates the application of ACO to minimize user delay at traffic intersections. Computer simulation results show that this new approach outperforms conventional fully actuated control under the condition of high traffic demand.

Food-for-protection mutualisms, interactions between two species in which one species provides protection from aspects of the biotic environment in exchange for a nutritional reward, show an exceptional degree of context dependency. The occurrence, strength, and outcome of these interactions often depend on the ecological context in which they take place. However, the causes and consequences of such context-dependent variation remain poorly understood. The protection mutualism involving lycaenid butterflies and ants provides an opportunity to explore many aspects of the ecology and evolution of interspecific interactions including the importance and predictability of ecological factors that produce context-dependent investment or outcomes in interspecific interactions. Ant-tended lycaenid larvae produce carbohydrate-rich secretions that are collected by attendant ants. In exchange for this food reward, ants may confer developmental benefits and protect larvae from predators and parasitoids. Both participants in this mutualism are capable of responding to changing ecological conditions and, thus, can quickly alter their level of investment or decision to participate in the interaction. In Appendix A, I present the results of field work that illustrate that ant tending provides the lycaenid butterfly, Hemiargus isola, with effective protection from parasitoid attack and enhanced larval survival. Lycaenids on plants from which ants were excluded were almost twice as likely to be parasitized as were lycaenids feeding on plants to which ants had access. In Appendix B, I present the results of laboratory experiments that show that the tentacular organ signal employed by H. isola is a generalized signal, conveyed by either a simple, tactile stimulus or a secretion of low volatility, which evokes an alarm response in attendant ants. Furthermore, I provide evidence to suggest that the function of the tentacular organ signal is context dependent and mediates lycaenid investment in the mutualism. In Appendix C, we present the results of laboratory experiments that demonstrate that altering the ratio of carbohydrate and protein resources available to ants influences their decision to participate in the mutualism with H. isola. Significantly more ants from colonies fed a low carbohydrate/high protein diet tended lycaenids relative to ants fed a high carbohydrate/low protein or high carbohydrate/high protein diet.

This diploma thesis deals with ant colony optimization for shortest path problems. In the theoretical part it describes Ant Colony Optimization. In the practical part ant colony optimization algorithms are selected for the design and implementation of shortest path problems in the Java.

In this work ant colony technologies for image processing are analyzed. Modifications of Max-Min ant system for automatic image pre-processing are proposed. Image segmentation by multiple ant colonies technique based on pheromone competition is proposed. Modified ant system is implemented in FPGA and MicroBlaze core units influence on performance is analyzed.
Darbe nagrinėjamos skruzdžių kolonijų technologijos vaizdams apdoroti. Pasiūlomos max-min skruzdžių sistemos modifikacijos tinkamos automatizuoti pirminį vaizdų apdorojimą. Pristatoma vaizdų segmentavimo metodika grįsta skruzdžių kolonijų varžymusi feromono pagalba. Nagrinėjama, įgyvendintos LPLM įrenginyje, modifikuotos skruzdžių sistemos sparta ir MicroBlaze modulių įtaka spartai.

The Argentine Ant, Linepithema humile (Hymenoptera: Formicidae), is one of the world's most successful invasive species and invades undisturbed Fynbos habitats in South Africa, displacing native arthropod species and affecting interspecific associations. In order to assess the impact of Li. humile on native ant assemblages and associations between ants and myrmecophilous butterflies (Lepidoptera: Lycaenidae) on the western slopes of Table Mountain (Cape Town, South Africa), adult butterfly density was scored and distribution of food plants were assessed at two sites.

Fire ants link their legs and jaws together to form functional structures called self- assemblages. Examples include floating rafts, towers, bridges, and bivouacs. We investigate these self-assemblages of fire ants. Our studies are motivated in part by the vision of providing guidance for programmable robot swarms. The goal for such systems is to develop a simple programmable element from which complex patterns or behaviors emerge on the collective level. Intelligence is decentralized, as is the case with social insects such as fire ants. In this combined experimental and theoretical study, we investigate the construction of two fire ant self-assemblages that are critical to the colony’s survival: the raft and the tower. Using time-lapse photography, we record the construction processes of rafts and towers in the laboratory. We identify and characterize individual ant behaviors that we consistently observe during assembly, and incorporate these behaviors into mathematical models of the assembly process. Our models accurately predict both the assemblages’ shapes and growth patterns, thus providing evidence that we have identified and analyzed the key mechanisms for these fire ant self-assemblages. We also develop novel techniques using scanning electron microscopy and micro-computed tomography scans to visualize and quantify the internal structure and packing properties of live linked fire ants. We compare our findings to packings of dead ants and similarly shaped granular material packings to understand how active arranging affects ant spacing and orientation. We find that ants use their legs to increase neighbor spacing and hence reduce their packing density by one-third compared to packings of dead ants. Also, we find that live ants do not align themselves in parallel with nearest neighbors as much as dead ants passively do. Our main contribution is the development of parsimonious mathematical models of how the behaviors of individuals result in the collective construction of fire ant assemblages. The models posit only simple observed behaviors based on local information, yet their mathe- matical analysis yields accurate predictions of assemblage shapes and construction rates for a wide range of ant colony sizes.

Thesis (Ph.D) - Swinburne University of Technology, Faculty of Information & Communication Technologies, Complex Intelligent Systems Laboratory, 2008.
Submitted in partial fulfilment for the degree of Doctor of Philosophy, Complex Intelligent Systems Laboratory, Faculty of Information and Communication Technologies, Swinburne University of Technology, 2008. Typescript. Includes bibliographical references (p. 169.181).

Die vorliegende Dissertation hat einen technologischen und einen anwendungsbezogenen Schwerpunkt. Technologisch ordnen sich die präsentierten Forschungsergebnisse in das Gebiet der "Swarm Intelligence" (dt.: Schwarm-Intelligenz) ein. Swarm Intelligence ist ein Teilbereich der Informatik, der sich an der Überschneidung zwischen der Multi-Agenten Systeme Forschung der Künstlichen Intelligenz und dem Forschungsgebiet "Artificial Life" (dt.: Künstliches Leben) befindet. Im Gegensatz zur Swarm Intelligence im allgemeinen, überträgt der spezielle Ansatz "Synthetic Ecosystems" (dt.: synthetische Ökosysteme) nicht nur Koordinationsmechanismen aus biologischen Multi-Agenten Systemen, wie zum Beispiel Insekten Kolonien, in den Entwurf künstlicher Systeme. Vielmehr sollen die grundlegenden Prinzipien "natürlich" entstandener komplexer Systeme, also auch zum Beispiel einer Aktienbörse, übernommen werden. Als anwendungsbezogener Hintergrund der Dissertation wurde die verteilte Steuerung moderner industrieller Fertigungsanlagen gewählt. Die Fertigungssteuerung ist ein geeignetes Anwendungsfeld für die Technologien, die im Rahmen der Forschungsarbeiten entwickelt wurden. Damit dient die Präsentation eines synthetischen Ökosystems für die Fertigungssteuerung der Demonstration des neuartigen Ansatzes zum Entwurf, Realisierung und Evaluierung komplexer, industriell relevanter Systeme. Gleichzeitig leistet die vorgestellte Architektur der Fertigungssteuerung und die darin verwandten Koordinationsverfahren einen Beitrag zur Weiterentwicklung holonischer Produktionssysteme. Der holonische Ansatz zur Produktionsplanung und -steuerung genießt derzeit große Aufmerksamkeit sowohl in der Forschung als auch in der Industrie. Als Teilgebiet der Entwicklung intelligenter Fertigungssysteme (engl.: IMS - Intelligent Manufacturing Systems), propagiert der holonische Ansatz eine Abkehr von der traditionell zentralistischen und hierarchischen Planung und Steuerung hin zu selbst-organisierenden Systemen autonom (inter-)agierender Individuen ("Holone"). Bei der praktischen Umsetzung holonischer Systeme werden sehr häufig Technologien aus der Multi-Agenten Systeme Forschung angewandt. Mit dieser Dissertation rücken auch synthetische Ökosysteme in das Blickfeld holonischer Systeme. Natürliche Agentensysteme im allgemeinen und Kolonien sozialer Insekten im besonderen faszinieren durch ihre Robustheit, ihre Flexibilität und ihre Anpassungsfähigkeit. Solche Systeme bestehen häufig aus sehr vielen, sehr einfachen Individuen und doch weisen sie ein komplexes und koordiniertes Gesamtverhalten auf. Es gibt mehrere Zweige in unterschiedlichen Wissenschaften, zum Beispiel in der Biologie, Physik, Ökonomie oder in der Informatik, die sich mit verteilten Systemen lokal interagierender Individuen beschäftigen. Ihre Erforschung resultiert in einer Reihe wiederholt beobachteter grundlegender Eigenschaften. Um künstlich erschaffene Systeme mit ähnlichen Eigenschaften auszustatten werden Entwurfsprinzipien für das Design von Multi-Agenten Systemen in dieser Dissertation vorgeschlagen. Jedes Entwurfsprinzip wird systematisch eingeführt, motiviert und in seinen Konsequenzen für Anwendungen in der Fertigungssteuerung diskutiert. Stigmergie ist ein grundlegendes Konzept der Koordination einer großen Anzahl von Individuen unter anderem in Kolonien sozialer Insekten. Die Formulierung dieses Konzepts ist auf den Biologen Grassè zurückzuführen, welcher in der Mitte des zwanzigsten Jahrhunderts das Schwarmverhalten von Termiten untersuchte. Stigmergie beruht auf der Tatsache, daß das Verhalten eines jeden Individuums durch die aktuelle Konfiguration seiner lokalen Umwelt bestimmt wird. Die Umwelt wiederum, wird durch die Aktivitäten der Individuen verändert. Diese Wechselwirkung führt in Verbindung mit entsprechend ausgelegten individuellen Verhaltensmustern zur Emergenz einer global koordinierten Erfüllung der anstehenden Aufgaben der Kolonie. Im Detail wird sematektonische von marker-basierter Stigmergie unterschieden, wobei bei sematektonischer Stigmergie der Zustand der Aufgabenerfüllung selbst (z.B. Stand des Nestbaus) das Individualverhalten beeinflußt, während marker-basierte Stigmergie aufgabenunabhängige Marker (z.B. Pheromone) in der Umwelt platziert. Multi-Agenten Systeme finden ihre Realisierung in Software, welche gegebenenfalls an physische Aktuatoren gekoppelt ist. Im allgemeinen besteht diese Software aus einer Laufzeitumgebung und den darin ausgeführten Agenten. Die vorliegende Dissertation präsentiert eine Erweiterung von Laufzeitumgebungen um eine anwendungsunabhängige Pheromon Infrastruktur (PI). Die PI ermöglicht es den Softwareagenten des jeweiligen synthetischen Ökosystems, künstliche Pheromone als Datenstrukturen in einem virtuellen Raum abzulegen und wahrzunehmen. Diese Datenstrukturen dienen als Marker in stigmergetischen Koordinationsmechanismen. Die Algorithmen der PI operieren auf diesen künstlichen Pheromonen und emulieren die natürlichen Vorgänge der räumlichen Ausbreitung und Verdunstung von Pheromonen auf abstrakter Ebene. Zusätzlich wird das natürliche Vorbild um eine automatische Aufbereitung von Informationen erweitert. Die Funktionalität der PI wird in dieser Dissertation spezifiziert. Des weiteren wird ein formales Modell erstellt, welches die Grundlage einer numerischen Analyse der Eigenschaften der PI bildet. Die Analyse liefert Vorhersagen für das Entstehen von räumlichen Mustern von Pheromonkonzentrationen in der PI. Diese Vorhersagen können dann in der Feineinstellung und der Evaluierung von Koordinationsmechanismen verwendet werden. Außerdem dient das formale Modell als Grundlage für den Beweis der globalen Stabilität der PI. Damit ist gesichert, daß unabhängig von der gewählten räumlichen Struktur und den von der jeweiligen Anwendung generierten Pheromonen die Konzentrationen der Pheromone immer in ihrer Stärke begrenzt sind. Der Beweis der globalen Stabilität ist eine wichtige Voraussetzung für die Verwendung der PI in praktischen Anwendungen. Die Spezifikation einer verteilten Realisierung der PI bildet den Abschluß der allgemeinen Betrachtung. Die Agenten, welche die (virtuelle) räumliche Struktur der PI widerspiegeln, werden im Detail spezifiziert. Auf der Basis dieser Spezifikation ist im Rahmen der Dissertation ein Prototyp der PI realisiert worden. Dieser Prototyp diente dem Nachweis des vorhergesagten Verhaltens der Infrastruktur und der späteren Evaluierung des entwickelten Fertigungssteuerungssystems. Im weiteren Verlauf der vorliegenden Dissertation wird ein neuartiger Ansatz zur Fertigungssteuerung betrachtet. Die absehbaren Veränderungen der äußeren Bedingungen der industriellen Produktion, ausgelöst durch den globalen Übergang von Anbieter- zu Verbrauchermärkten, erfordert die Fertigung immer komplexerer und variantenreicherer Produkte in ständig schwankenden Stückzahlen und deutlich verkürzten Lebenszyklen bei gleichzeitig sinkenden Kosten. Zur Erfüllung dieser Anforderungen in der Massenproduktion wandelt sich die traditionell starr verkettete Strangfertigung (z.B. Transferstraßen) zur flexiblen Fließfertigung (z.B. flexible Bearbeitungszentren). Die Steuerung einer flexiblen Fließfertigung erfordert neue Herangehensweisen. In einer holonischen Fertigung, zum Beispiel, organisiert sich die Produktionsplanung und Produktionssteuerung selbst um die Erfüllung der aktuellen Aufträge. Dabei werden in der Steuerung verteilte, reaktive Verfahren verwendet, welche eine deutlich gesteigerte Robustheit und Flexibilität gegenüber Störungen und Veränderungen aufweisen. Der Übergang zur flexiblen Fließfertigung bedeutet die Einführung von Flexibilität in der Bearbeitung aber auch im Transport des Materials. Es ist eine grundlegende Eigenschaft dieser Fertigungssysteme, daß zu einem beliebigen Zeitpunkt eine Reihe möglicher Transportwege und damit eine Vielzahl möglicher Muster im Materialfluß zur Verfügung stehen. Dabei führt aber nur eine kleine Menge dieser Muster zu einer bestmöglichen Erfüllung der globalen Produktionsziele (z.B. hoher globaler Durchsatz). Es ist also die Aufgabe der Fertigungssteuerung in jeder Situation das bestmögliche Materialflußmuster zu erreichen. Ist ein verteilter Ansatz für die Steuerung gewählt worden, so muß diese Optimierung nach globalen Produktionszielen in die lokalen Steuerungsentscheidungen integriert werden, ohne die Autonomie der lokalen Einheiten zu verletzen. Die Dissertation präsentiert ein sogenanntes geführtes Fertigungssteuerungssystem (GFSS), welches einen verteilten und reaktiven Steuerungsansatz mit einer Flußoptimierung unter Beachtung globaler Produktionsziele in neuartiger Weise verbindet. Der Entwurf des GFSS folgte den vorgeschlagenen Prinzipien für synthetische Ökosysteme und die Agenten im GFSS werden mit Hilfe der Pheromon Infrastruktur koordiniert. Die Agenten und Pheromone des GFSS werden detailliert spezifiziert und in einem realistischen Beispiel aus der Automobilindustrie evaluiert. In der Evaluierung wird von den Ergebnissen der Analyse der PI Gebrauch gemacht. Die dabei gewählte numerische Beschreibung des Einzelverhaltens und die darauf aufbauende Betrachtung des emergierenden Gesamtverhaltens weist den Weg zu einer systematischen Evaluierung von emergenten Systemeigenschaften in synthetischen Ökosystemen. In einem abschließenden Kapitel werden die drei inhaltlichen Schwerpunkte der Dissertation noch einmal betrachtet. Vor dem Hintergrund des GFSS werden die vorgeschlagenen Entwurfsprinzipien für synthetische Ökosysteme systematisch auf ihre Anwendbarkeit und praktische Bedeutung hin überprüft. Außerdem wird die allgemeine Verwendung der PI für den Austausch von Informationen zwischen Agenten untersucht. Und schließlich wird die Fertigungssteuerung aus der Sicht abstrakter Zustandsräume diskutiert. Die vorliegende Dissertation weist den Weg für eine Reihe weiterführender Forschungsarbeiten. So werden zum einen detaillierte Konzepte für die Erweiterung des GFSS um eine automatische Strategiebewertung und -generierung und um ein Visualisierungssystem vorgestellt. Zum anderen werden aber auch notwendige Ergänzungen der Entwurfsprinzipien und mögliche Verbesserungen der PI und des darauf basierenden Evaluierungsansatzes vorgeschlagen.
The synthetic ecosystems approach attempts to adopt basic principles of natural ecosystems in the design of multiagent systems. Natural agent systems like insect colonies are fascinating in that they are robust, flexible, and adaptive. Made up of millions of very simple entities, these systems express a highly complex and coordinated global behavior. There are several branches in different sciences, for instance in biology, physics, economics, or in computer science, that focus on distributed systems of locally interacting entities. Their research yields a number of commonly observed characteristics. To supply engineered systems with similar characteristics this thesis proposes a set of principles that should be observed when designing synthetic ecosystems. Each principle is systematically stated and motivated, and its consequences for the manufacturing control domain are discussed. Stigmergy has shown its usefulness in the coordination of large crowds of agents in a synthetic ecosystem. Sign-based stigmergy through synthetic pheromones is supported by an extension to runtime environments for software agents called the pheromone infrastructure. In this thesis the operation of the pheromone infrastructure is specified, formally modeled and analyzed, and an implementation is presented. The guided manufacturing control system for flexible flow shops is designed following the proposed principles and it uses the pheromone infrastructure to coordinate its agents. It comprises two subsystems. The control (sub)system, which enables production, is distributed and reactive. The advisory (sub)system observes the operation of the control system and advises the manufacturing execution under global considerations. This thesis specifies the guided manufacturing control system and evaluates its operation in a simple but realistic example adapted from the automotive industry. The applicability of the design principles, the usage of the pheromone infrastructure, and the operation of manufacturing control in abstract state spaces are considered on the basis of the guided manufacturing control system.

Rapporten presenterar det examensarbetet som har gått ut på att undersöka möjligheterna att konstruera en sensor som mäter kadens med hjälp av en accelerometer. Implementation av kadensprofilen till ANT+ har gjorts för att möjliggöra synkronisering mellan en sportklocka och sensorn. Kadens är hur fort cyklisten trampar med pedalerna mätt i enheten Varv per minut vanligt förkortat RPM från engelskans Revolutions Per Minute. Hur fort en cyklist trampar påverkar kroppen på många olika sätt och ofta vill cyklisten veta vad aktuell kadens är för att optimera sin prestation. Den undersökta principen att använda en accelerometer för att mäta kadens syftar till att en eventuell prototyp skulle vara lämplig till inomhuscykling även kallad spinning. På en vanlig traditionell cykel har man oftast två hårdvarudelar för att mäta kadens, en monterad på pedalarmen och den andra på cykelramen. Cykelramen på en spinningcykel skiljer sig så pass mot en vanlig cykel att hårdvarudelen som ska sitta på cykelramen inte kan monteras med samma lätthet. Med en accelerometer behövs bara en hårdvarudel som lätt kan monteras på pedalarmen på cykeln. Programutvecklingen har skett med ett Arduino Uno  som består av en ATmega328 mikrokontroller från Atmel. Sensorenheten som mäter kadensen består av Arduino Uno, accelerometern LSM303DLHC från STMicroelectronics och ANT-chippet nRF24AP2 från Nordic Semiconductor. Huvudenheten har bestått av en persondator som har agerat mottagare med programmet ANT+ Simulator. Det utvecklade programmet på mikrokontrollen upptäcker när det sker ett pedalvarv och skickar den totala varvtiden tillsammans med antal pedalvarv som totalt inträffat till nRF24AP2 vidare till huvudenheten. Kadensprofilen är den som räknar ut vad aktuell kadens är. Avslutningsvis presenteras ett minimumkrav av hårdvaran och ett förslag av en energisnål mikrokontroller för en eventuell prototyp.

Insertion of transposable elements within an operon has been known not only to abolish expression of the gene interrupted by the insertion, but also to exert a strong polar effect on the expression of downstream genes in the same operon. In this dissertation, I have shown that insertions of the transposable ampicillin-resistance element Tn1, either in the polar or nonpolar orientation, in the 3' untranslated region of the bacteriophage P22 antirepressor (ant) operon reduce the rate of upstream ant gene expression; insertions of Tn1 in the nonpolar orientation reduce the rate of ant gene expression more significantly than those in the polar orientation. This effect appears to be due to reduced stability of ant mRNA. Tn1 deletion mutants of one of the nonpolar Tn1 insertion mutations have been isolated. Two classes of Tn1 deletions are obtained. Class I retains a 68 bp Tn1 sequence that shows a potential 14 bp stem and 37 bp loop conformation, while class II retains 147 bp Tn1 sequence that shows a potential 69 bp stem and 6 bp loop conformation. These two classes of Tn1 deletions do not delete any P22 sequences. Class I but not class II Tn1 deletion mutants restore the rate of ant gene expression and ant mRNA stability. Six different Ant+ revertants of the class II Tn1 deletion mutant simultaneously restore the rate of ant gene expression and ant mRNA stability. They all have deletions that remove all or part of the class II Tn1 sequence. In one case, the Tn1 sequence retained shows a potential 15 bp stem and 8 bp loop conformation, in the other cases, no secondary structure is predicted to form. The results of the Tn1 deletion mutants suggest that the stem-and-loop structures and the length of stems potentially formed by the Tn1 sequences in mRNA may affect its stability.

Ant algorithms were first written about in 1991 and since then they have been applied to many problems with great success. During these years the algorithms themselves have been modified for improved performance and also been influenced by research in other fields. Since the earliest Ant algorithms, heuristics and local search have been the primary knowledge sources. This thesis asks the question "how is knowledge used in Ant algorithms?" To answer this question three Ant algorithms are implemented. The first is the Graph based Ant System (GBAS), a theoretical model not yet implemented, and the others are two influential algorithms, the Ant System and Max-Min Ant System. A comparison is undertaken to show that the theoretical model empirically models what happens in the other two algorithms. Therefore, this chapter explores whether different pheromone matrices (representing the internal knowledge) have a significant effect on the behaviour of the algorithm. It is shown that only under extreme parameter settings does the behaviour of Ant System and Max-Min Ant System differ from that of GBAS. The thesis continues by investigating how inaccurate knowledge is used when it is the heuristic that is at fault. This study reveals that Ant algorithms are not good at dealing with this information, and if they do use a heuristic they must rely on it relating valid guidance. An additional benefit of this study is that it shows heuristics may offer more control over the exploration-exploitation trade-off than is afforded by other parameters. The second point where knowledge enters the algorithm is through the local search. The thesis looks at what happens to the performance of the Ant algorithms when a local search is used and how this affects the parameters of the algorithm. It is shown that the addition of a local search method does change the behaviour of the algorithm and that the strength of the method has a strong influence on how the parameters are chosen. The final study focuses on whether Ant algorithms are effective for driving a local search method. The thesis demonstrates that these algorithms are not as effective as some simpler fixed and variable neighbourhood search methods.

As flower visitors, ants rarely benefit a plant, commonly disrupting pollination by deterring other flower visitors, or stealing nectar. This thesis examines three aspects of ant-flower interactions, focusing on the occurrence of floral traits that prevent disruption of pollination and a novel means by which ants may influence pollinator behaviour. To assess which types of plant species possess ant-repelling floral traits I carried out a survey of 49 Neotropical plant species. Around a third of these species were repellent to the common generalist ant Camponotus novograndensis (Formicinae). This repellence was positively correlated with large nectar volumes within individual flowers. It appears that there has been selection for floral ant-repellence as a defence against ant thieves in plant species that invest in large volumes of nectar. In some cases these repellent traits were effective against a wide range of ant species. However, in no plant species were predacious ants particularly repelled, indicating that there may be little selective pressure on non-ant-plants to defend potential pollinators from aggressive ants. To investigate the importance of coevolution in determining the effectiveness of ant-repellents, a small but diverse range of Mediterranean plant species were tested with the invasive nectar thieving ant Linepithema humile (Dolichoderinae) and the native but non-nectar thieving ant Messor bouvieri (Myrmecinae). Responses of both ant species to floral traits were very similar. The ability of some plants to restrict access to ant species with which they have no evolutionary history may help to reduce the impact invasive species, as nectar thieves, have on plant-pollinator interactions. It is reported that flowers recently visited by bees and hoverflies may be rejected for a period of time by subsequent bee visitors through the detection of scent-marks. Nectar-thieving ants could potentially influence the foraging decisions of bees in a similar way if they come to associate ant trail pheromones or footprint hydrocarbons with poor reward levels. However, my empirical work found no differences were found in bee visitation behaviour between flowers of Digitalis pupurea (Plantaginaceae), Bupleurum fruticosum (Apiaceae) or Brassica juncea (Brassicaceae) that had been in contact with ants and control flowers. Ant-attendance at flowers of these species may not reduce reward levels sufficiently to make it worthwhile for bees to incorporate ant scent-marks into foraging decisions. Investigations like these into the interactions between ants, flowers and other flower visitors are essential if we hope to understand the part ants play in pollination ecology, and determine how ants have helped shape floral evolution.

In this thesis the organisation of colonies of the ant, Temnothorax albipennis, is investigated with a special focus on their spatial and temporal statistics. Individual-based modelling combined with analyses of experimental data are used extensively to infer the mechanisms that govern individual and collective behaviour. The unequal allocation of labour amongst different individuals, as manifested in skewed distributions of activity, is ubiquitous within the social insects. Early non-spatial individual-based models demonstrated that such skewed divisions of labour can self- organise through the interaction of fluctuating levels of stimuli associated with a task, with differentially sensitive agents that perform work upon the stimulus. Here, that modelling framework is extended by explicitly including space. This modification induces a 'percolation' effect, in which small differences amongst agents in their response thresholds, are related to large differences in their probabilities of performing work. The extension of the original fixed-threshold models of Division of Labour to include space means that they can be treated as a special case of diffusion in disordered media - a well studied branch of statistical mechanics. Staying at home to care for young or leaving to find food is one of the most fundamental divisions of labour. Here the rate of departures from ant nests and the collective activity of the individuals within the nest, are experimentally quantified. Both the rate of nest-leaving, and the inside-nest activity showed a non-linear decline over time. This and other results indicates that fluctuating record signals and repulsive ant-ant interactions play a significant role in colony organisation. A record signal is a new 'high water mark' in the history of a system. The dynamics of several complex but purely physical systems are also based on record signals but this is the first time they have been experimentally shown in a biological system. Finally, the generation of spatial pattern formation is experimentally investigated In the context of resilience to perturbations. The brood within the ant colony is often sorted into an intricate annular pattern, according to the developmental stage of the various rood types. Even after the pattern is completely destroyed, the workers are able to re-establish the pattern. The dynamics of this process of re-emergence is quantified in detail. Lastly, the possible utility of the pattern as a spatial cue to the workers is discussed.

SANTRAUKA Tapyba ant šilko – tai menas, artimas jausmams. Ši technologija atsirado Kinijoje ir paplito po visą pasaulį, tik kiekviena tauta tapybą ant šilko suprato ir interpretavo savaip. Tapyba ant šilko šiandien yra labai populiarus ir mielas užsiėmimas. Tapybos ant šilko tecnikos domina ne tik menininkus, bet ir moteris, moytojus bei moksleives. Šis užsiėmimas koordinuoja mokinių veiklą, kuri sužadina smalsumą, aktyvumą, skatina mąstymą. Taigi mano darbo tema: Tapyba ant šilko „Aguonų pieva”. Pasirinkau šį augalo motyvą, nes aguonos – išlikimo ir trapumo simbolis, kuris rečiau sutinkamas lietuvių ornamentikoje, o tai dar labiau paskatino pasidomėti būtent aguonų motyvo tapyba. Darbo tikslas: Paanalizuoti aguonos augalą istorijoje, mitologijoje, simbolikoje, tautosakoje ir pavaizduoti jį tapant ant šilko. Darbo uždaviniai: Panagrinėti aguonos augalo atsiradimo istoriją, simboliką. Paanalizuoti aguonos žiedo reikšmę mitologijoje, tautosakoje. Panagrinėti aguonų neigiamą ir teigiamą poveikį žmogaus sveikatai. Apžvelgti tapybos ant šilko istoriją ir technikas. Paanalizuoti tapybos ant šilko technikų panaudojimą technologijų pamokose. Atlikti kūrybinį darbą „Aguonų pieva“. Metodai. Informacinių šaltinių analizė, mokinių pasiekimų analizė technologijų pamokose, kūrybinis darbas. Šiame darbe aprašomas kūrybinio darbo atlikimas. Savo kūrybiniame darbe pasirinkau vaizduoti aguonų pievą. Aguonų pievos kompoziciją sudaro trys dalys. Sustačius visas tris kompozicijas į vieną... [toliau žr. visą tekstą]
SUMMARY Painting on silk - is the art of close feelings. This technology emerged in China and has spread all over the world, but every nation understood the painting on silk and interpreted it in their own way. Paintings on silk are very popular and lovely occupation. Not only artists, but women, teachers and students are interested about painting on silk. This activity coordinates the activities of students, which stimulates curiosity, activity, stimulate thinking. So, my work theme is: Painting on silk “Poppy meadow”. I chose this motif of a plant, because poppy - a symbol of survival and fragility, which is less frequently encountered in Lithuanian ornamentation and this reason, further encouraged finding out precisely poppy motif paintings. Work aim: to analyze the poppy crop in history, mythology, symbolism, and folklore represented by painting on silk. Work tasks: To explore the history and symbolism of poppy plants; To analyze the significance of poppies ring in mythology and folklore; To explore the poppy negative and positive effects for human health; To review the history and techniques of painting on silk; To analyze the techniques of painting on silk adaptation in technology lessons; To do a creative work: “ Poppy meadow”. Work methods: Information Resource analysis; student achievement analysis in technology lessons, creative work. This work describes the performance of creative work. I decided to paint a poppy meadow. The composition of... [to full text]

The distribution of resources is vital to any system or society. This is particularly true of social insect colonies where independent access to resources is not available to all members. Only a fraction of individuals are responsible for obtaining food for the colony from outside the nest. Surprisingly little is known about how this food is subsequently distributed to members inside the nest. The work in this thesis is focused around a set of food distribution experiments conducted using four colonies of the ant Temnothorax albipennis. The study applies a well-used technique in a new way to investigate the distribution of food under two different scenarios: feeding under normal conditions and famine relief feeding after a period of starvation. All ants in each colony are marked and then individually tracked recording every feeding interaction to obtain a complete network of food transmission. This work has shown that all four colonies efficiently relieved the famine within 30 minutes of introducing new food. This process was facilitated by workers abandoning their spatial structure and expanding their space use; feeding multiple recipients from a single donor; and simultaneously spreading stored food and new food. Recruitment of foragers did not play a major role in relieving the famine but foragers were responsible for most of the first round of feeding. The study revealed that not all members received the same amount of food and most ants received food in multiple feeding interactions. The transmission pathways used to distribute the food present an opportunity for harmful substances to spread. The pathways are explored in this context to see whether the colonies might aim to minimize the spread by partitioning the pathways or maximise spread by mixing to promote social immunity. The study reveals behavioural differences between the four colonies which are likely to result from the inherent variation in demographic and geometric properties. These differences highlight the flexibility of ant colonies during problem solving under different conditions.

Thesis (M.S.) -- University of Maryland, College Park, 2007.
Thesis research directed by: Dept. of Entomology. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

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Este trabalho tem em vista observar a identidade de mulheres negras a partir da s?rie de televis?o Ant?nia. Para tanto observaremos elementos da cultura e identidade negra e abriremos espa?o para a discuss?o das rela??es de g?nero e a uni?o entre os fatores etnia e g?nero. Posteriormente analisaremos o contexto de produ??o que envolveu o programa de duas formas, situando a conjun??o s?cio-pol?tica e cultural do pa?s atrav?s de reportagens selecionadas das revistas Veja e Ra?a Brasil em um determinado per?odo de tempo. Em um segundo instante faremos uma revis?o sobre o espa?o do negro na televis?o brasileira, considerando momentos importantes de d?cadas passadas e o atual momento de trocas com o cinema nacional, onde se insere Ant?nia. Assim pretendemos abrir o horizonte sobre esta nova proposta de representa??o de uma parcela populacional frequentemente negligenciada pela cultura da m?dia, para enfim analisarmos a s?rie Ant?nia e as formas de identidade que esta apresenta ?s mulheres negras, observando duas perspectivas, a rela??o de g?neros e a negritude. Para tanto nos nortearemos por autores como Stuart Hall, Paul Gilroy e Douglas Kellner.

The butterfly family Lycaenidae (including the Riodinidae) contains an estimated 30% of all butterfly species and exhibits a diverse array of life history strategies. The early stages of most lycaenids associate with ants to varying degrees, ranging from casual facultative coexistence through to obligate association where the long-term survival of the butterfly is dependent on the presence of its attendant ants. Attendant ants guard the butterflies against predators and parasites during their vulnerable period of larval growth and pupation. The caterpillars, in return, reward the ants by providing attractive secretions from specialized glands in their cuticle. The prevalence of caterpillar-ant associations in the species rich Lycaenidae is in contrast with other Lepidoptera, where ant association appears only as isolated cases in otherwise non ant-associated lineages. This has led to the proposal that ant association may have influenced lycaenid diversification or even enhanced the rates of speciation in the group. In contrast, facultative ant-associated butterflies exhibit high levels of host plant integrity, so it is reasonable to assume that host plants may have played a significant role in their diversification. Since the influence of ants (or plants) on diversification is independent of geographic speciation modes such as vicariance or peripheral isolates, there is an underlying inference of sympatric speciation. Certain prerequisites thought to be important for sympatric speciation, such as mating on the host plant (or in the presence of the appropriate ant) as well as ant dependent oviposition preferences are characteristic of many obligate myrmecophiles. Not surprisingly, it has been suggested that evidence for sympatric speciation is more likely to be found in the Insecta since this additional mode of diversification could account for the large numbers of insect species. This thesis tested the diversification processes in obligate and facultative ant associated lycaenids using comparative methodologies in hierarchical molecular phylogenetic analyses. First, several hypotheses relating to the influence of ants on diversification in obligately ant associated lycaenid butterflies were tested in a phylogeographic analysis of the Australian endemic Jalmenus evagoras. The phylogeographic analysis revealed that regional isolation of butterfly subpopulations coincident with locally adapted ant taxa could generate a phylogenetic pattern in which related lycaenids would be seen to associate with related or ecologically similar ants. Likewise, ecological shifts in habitat preferences by lycaenids could lead to co-diversification with habitat specialist ants, even though in both cases, the ants may play only an incidental role in the diversification process. A comparative methodology was then applied in a molecular phylogenetic analysis of the genus Jalmenus to test for a signal of diversification consistent with shifts in ant partners, and to infer the processes by which ants could influence speciation. Several other specific hypotheses relating to monophyly and taxonomy were also examined. Comparative analysis of the Jalmenus phylogeny found that attendant ant shifts coincided with high levels of sympatry among sister species. This pattern could be explained by sympatric speciation; however, data suggested it was more likely that ant shifts occurred during butterfly population expansions as a result of vegetation and climate changes in the Pleistocene. Fragmentation of populations associating with novel ants could promote rapid ecological and behavioural changes and this could result in reproductive isolation of conspecifics when in secondary contact. Diversification would then continue in sympatry. In contrast, secondary contact of populations associating with the same ant species would result in homogenisation of the two lycaenid lineages or the extinction of one. A phylogeographic analysis of the facultative myrmecophiles, Theclinesthes albocincta/T. hesperia, was then undertaken to infer the evolutionary processes (such as the effects of host plant shifts) that could result in extant demographics. Species-specific questions of taxonomy, relative population ages and dispersal routes in arid Australia were also addressed. Results from the analysis suggested the two taxa were conspecific and had diversified in the late Pleistocene as a consequence of isolation in refugia in and around the arid areas of mainland Australia. However, as was the case in the J. evagoras population analysis in which attendant ant shifts were not detected, host plant shifts were not detected in the population analysis of T. albocincta/hesperia. Host plant or attendant ant shifts manifest more frequently at the species level, thus it was necessary to test the influence of host plant shifts at this higher level. The comparative methodology was then applied to a molecular phylogenetic analysis of the facultative ant-associated section Theclinesthes (comprising Theclinesthes, Sahulana and Neolucia) to test for modes of diversification consistent with host plant shifts. The relative importance of other influences on diversification was also assessed. Akin to the Jalmenus analysis, the prediction that sister species ranges should broadly overlap when a shift in host plants had taken place was upheld in the comparative analysis. Species in the genera Jalmenus and Theclinesthes were found to have diversified in the Pleistocene so were subject to the same climatic oscillations that influenced patterns of vegetation expansion and contraction across much of Australia. Thus, the similarity and predictability of relationships in the comparative analyses based on biological data suggested that host plant shifts have influenced diversification in facultative myrmecophiles by inhibiting gene flow in secondary contact in similar fashion to that of attendant ant shifts identified in the Jalmenus phylogeny. Interpretation of data in these analyses suggested that allopatric diversification was the most common mode of speciation. Isolation was inferred to be the result of fragmentation following long distance dispersal across wide expanses of marginal habitat, or vicariance following the closing of biogeographical barriers. However, attendant-ant and host-plant shifts clearly played an important role in the diversification process, and in the maintenance of species integrity among lycaenid butterflies. Furthermore, exceptions to the predicted patterns of range overlap and ecological shifts provided clues to additional modes of diversification including shifts in habitat preferences and an unusual temporal shift following changes in specific host plant phenology resulting in allochronic diversification. Inferring modes of diversification using comparative methods based on range overlap and biological traits in a phylogenetic context is not new; however, the interpretation presented in this thesis is in contrast with contemporary methods. It is clear that the patterns of species range overlap and the ecological preferences of sister taxa are intimately related among lycaenid species that diversified during the Pleistocene. As a result, different influences on diversification can be highlighted in phylogenies when applying existing comparative methodologies but without necessarily drawing the same conclusions about modes of diversification. A more inclusive explanation for patterns of range overlap among sister taxa is detailed, a consequence of which is a method for estimating rates of extinction in a phylogeny where comprehensive distributional, biological and taxonomic data are available. These patterns and predictions may be applicable to a range of taxa, especially those that have diversified in the Pleistocene. Plans for future studies are outlined.

This thesis is prepared in three parts; the first part is a study of the ant species of the southern Carnarvon Basin, which was undertaken in order to determine the patterns of ant species distribution in this arid zone area. The distribution patterns were looked at in terms of biogeographical regions and they demonstrated the transitional nature of this particular area. Recommendations to alter the border between the South-west Province and the Eremaean Province were supported. The next chapter of this thesis analysed ant species from long unburnt and burnt areas of three main vegetation types (two Triodia species grasslands and Acacia aneura woodlands) in the Gibson Desert Nature Reserve. This study was carried out to observe the recovery of ant populations after fire. The results provided further evidence that invertebrates are measurably impacted by fire in the arid zone. The final chapter is a comparison of these two arid zone studies with six other ant community studies from throughout Western Australia. It demonstrated the uniqueness of some arid zone sites as well as related each study to each other according to their ant communities.

Numerous organizations collect and distribute non-aggregate personal data for a variety of different purposes, including demographic and public health research. In these situations, the data distributor is responsible with the protection of the anonymity and personal information of individuals. Microaggregation is one of the most commonly used statistical disclosure control methods. In microaggregation, the set of original records is first partitioned into several groups. The records in the same group are similar to each other. The minimum number of records in each group is k. Each record is replaced by the mean value of the group (centroid). The confidentiality of records is protected by ensuring that each group has at least a minimum of k records and each record is indistinguishable from at least k-1 other records in the microaggregated dataset. The goal of this process is to keep the within-group homogeneity higher and the information loss lower, where information loss is the sum squared deviation between the actual records and the group centroids. Several heuristics have been proposed for the NP-hard minimum information loss microaggregation problem. Among the most promising methods is the multivariate Hansen-Mukherjee (MHM) algorithm that uses a shortest path algorithm to identify the best partition consistent with a specified ordering of records. Developing improved heuristics for ordering multivariate points for microaggregation remains an open research challenge. This dissertation adapts a version of the population-based ant colony optimization algorithm (PACO) to order records within which MHM algorithm is used iteratively to improve the quality of grouping. Results of computational experiments using benchmark test problems indicate that P-ACO/MHM based microaggregation algorithm yields comparable or improved information loss than those obtained by extant methods.

As the largest third-party payment platform in China, Alipay has joined the team of making the world greener with the embedded cute mini APP--Ant Forest. Why are so many Alipay users willing to plant trees through Ant Forest? What are the motivations that affect their continued planting for months or even years? Based on the previous literature, we outlined a new framework to investigate the motivation in Ant Forest. The data were collected through a pilot study and semi-structured interviews with fourteen Chinese Alipay users; at the same time, they are Ant Forest participants. This article analyzes how intrinsic motivations (enjoyment, fulfillment, altruism, social interaction, identification), extrinsic motivations (external rewards, reciprocity, competition) influencing Chinese users to participate in Ant Forest, and whether these motivations have different influences and relationships when motivating participants. What’s more, we can through intrinsic motivation and extrinsic motivation to know how a mini-app that aggregates multiple features can attract users' continued participation, and give suggestions to the firm.

The Cross-Entropy Ant System (CEAS) has been implemented in ns-3. The implementation has been validated against the latest ns-2 implementation and some extra simulations have been performed. Apart from that, experiences with ns-3 have been described as part of the thesis.

Combinatorial optimization problems are of high academical as well as practical importance. Many instances of relevant combinatorial optimization problems are, due to their dimensions, intractable for complete methods such as branch and bound. Therefore, approximate algorithms such as metaheuristics received much attention in the past 20 years. Examples of metaheuristics are simulated annealing, tabu search, and evolutionary computation. One of the most recent metaheuristics is ant colony optimization (ACO), which was developed by Prof. M. Dorigo (who is the supervisor of this thesis) and colleagues. This thesis deals with theoretical as well as practical aspects of ant colony optimization.

* A survey of metaheuristics. Chapter 1 gives an extensive overview on the nowadays most important metaheuristics. This overview points out the importance of two important concepts in metaheuristics: intensification and diversification.

* The hyper-cube framework. Chapter 2 introduces a new framework for implementing ACO algorithms. This framework brings two main benefits to ACO researchers. First, from the point of view of the theoretician: we prove that Ant System (the first ACO algorithm to be proposed in the literature) in the hyper-cube framework generates solutions whose expected quality monotonically increases with the number of algorithm iterations when applied to unconstrained problems. Second, from the point of view of the experimental researcher, we show through examples that the implementation of ACO algorithms in the hyper-cube framework increases their robustness and makes the handling of the pheromone values easier.

* Deception. In the first part of Chapter 3 we formally define the notions of first and second order deception in ant colony optimization. Hereby, first order deception corresponds to deception as defined in the field of evolutionary computation and is therefore a bias introduced by the problem (instance) to be solved. Second order deception is an ACO-specific phenomenon. It describes the observation that the quality of the solutions generated by ACO algorithms may decrease over time in certain settings. In the second part of Chapter 3 we propose different ways of avoiding second order deception.

* ACO for the KCT problem. In Chapter 4 we outline an ACO algorithm for the edge-weighted k-cardinality tree (KCT) problem. This algorithm is implemented in the hyper-cube framework and uses a pheromone model that was determined to be well-working in Chapter 3. Together with the evolutionary computation and the tabu search approaches that we develop in Chapter 4, this ACO algorithm belongs to the current state-of-the-art algorithms for the KCT problem.

* ACO for the GSS problem. Chapter 5 describes a new ACO algorithm for the group shop scheduling (GSS) problem, which is a general shop scheduling problem that includes among others the well-known job shop scheduling (JSS) and the open shop scheduling (OSS) problems. This ACO algorithm, which is implemented in the hyper-cube framework and which uses a new pheromone model that was experimentally tested in Chapter 3, is currently the best ACO algorithm for the JSS as well as the OSS problem. In particular when applied to OSS problem instances, this algorithm obtains excellent results, improving the best known solution for several OSS benchmark instances. A final contribution of this thesis is the development of a general method for the solution of combinatorial optimization problems which we refer to as Beam-ACO. This method is a hybrid between ACO and a tree search technique known as beam search. We show that Beam-ACO is currently a state-of-the-art method for the application to the existing open shop scheduling (OSS) problem instances.

Doctorat en sciences appliquées
info:eu-repo/semantics/nonPublished

Namibia has high levels of diversity and endemism, and is recognised as a priority region for conservation . Ants are important components of arid ecosystems, they are ecologically dominant and drive vital processes, but there are few studies of them in Namibia. Ant-plant interactions form a significant area of ecological research; a classic example being the swollen-thorn acacias of Africa. This thesis describes Namibian ground and arboreal ant diversity and dominance, and characterises the ecology of a novel ant-acacia mutualism. I demonstrate that ant species richness and composition is highly variable across three arid Namibian habitats; saltpan, savannah and desert. Arboreal ants are shown to be a unique component of diversity, despite lower species richness than ground ants. The abundance of dominant ants influences species richness on the ground, but not on vegetation. In contrast to most ant-plant systems, individual camelthorn acacia trees, Vachellia erioloba, are stably and simultaneously inhabited by multiple ant species that nest within swollen-thorn domatia. The ant community on V. erioloba provides defence against herbivorous insects, although their effectiveness varies with herbivore identity. Nest site selection by the four taxonomically diverse ant species on V. erioloba is based on domatia morphology. Colony size increases with domatia size, but each species responds differently to availability of nesting space through varying levels of investment in brood production. Ants inhabiting myrmecophytes are thought to be nest-site limited and under intense competition. Unusually, on V. erioloba this is not the case, which may facilitate the rare coexistence of multiple ant species on individual host plants in this system. My research highlights the need for further work on ant diversity and ant-plant mutualisms in Namibia. The implications of this work are discussed and directions for future research suggested.

The ant colony optimization (ACO) metaheuristic is inspired by the foraging behaviour of real ant colonies. Similarly with other metaheuristics, ACO suffers from stagnation behaviour, where all ants construct the same solution from early stages. In result, the solution quality may be degraded because the population may get trapped on local optima. In this thesis, we propose a novel approach, called direct communication (DC) scheme, that helps ACO algorithms to escape from a local optimum if they get trapped. The experimental results on two routing problems showed that the DC scheme is effective. Usually, researchers are focused on problems in which they have static environment. In the last decade, there is a growing interest to apply nature-inspired metaheuristics in optimization problems with dynamic environments. Usually, dynamic optimization problems (DOPs) are addressed using evolutionary algorithms. In this thesis, we apply several novel ACO algorithms in two routing DOPs. The proposed ACO algorithms are integrated with immigrants schemes in which immigrant ants are generated, either randomly or with the use of knowledge from previous environment(s), and replace other ants in the current population. The experimental results showed that each proposed algorithm performs better in different dynamic cases, and that they have better performance than other peer ACO algorithms in general. The existing benchmark generators for DOPs are developed for binary-encoded combinatorial problems. Since routing problems are usually permutation-encoded combinatorial problems, the dynamic environments used in the experiments are generated using a novel benchmark generator that converts a static problem instance to a dynamic one. The specific dynamic benchmark generator changes the fitness landscape of the problem, which causes the optimum to change in every environmental change. Furthermore in this thesis, another benchmark generator is proposed which moves the population to another location in the fitness landscape, instead of modifying it. In this way, the optimum is known and one can see how close to the optimum an algorithm performs during the environmental changes.

The evolution of species interactions is a fascinating subject, and one of vital importance if we are to understand how biological communities change over time. This thesis considers the interaction between aphids (Homoptera) and ants (Formicidae). Ants tend aphids for sugary honeydew and in return provide a variety of protective services. A literature review in Chapter 1 introduces the subject and provides background information. Chapter 2 considers ant- aphid interactions in a community setting. Specifically, I consider the fitness effects of the ant- aphid interaction on host plants. Net benefits or costs to plants depend on the densities of ants and aphids; these densities may themselves change depending on context dependent factors. Chapters 3 and 4 consider how semiochemicals can allow species to respectively maintain or avoid synchrony in space and time with mutualists or antagonists. Chapter 3 shows ladybirds avoid prey patches guarded by ants by reducing oviposition in response to ant semiochemicals. Chapter 4 shows that aphid walking dispersal can be limited by ant semiochemicals. This may be adaptive for aphids to remain in areas of enemy- free space. Alternatively, if levels of kin competition are high limited dispersal could be costly to aphids. In Chapter 5 I consider interactions between invasive and native ants. Ecological dominance in ants may be mediated by the ability to monopolise honeydew- producing resources. Chapter 6 explores ants’ decisions whether to tend or prey upon aphids. Predation of aphids depends on colony demand (e.g. through cues from the presence of larvae) as well as the quality or quantity of supply (e.g. increased predation of unproductive aphids). Finally, Chapter 7 deals with macroevolutionary patterns in the interaction between ants and aphids. Specifically, I identify ecological traits that characterise aphid- tending ants. A final discussion chapter summarises how ant-aphid interactions fit into existing mutualism theory.

Thesis (MSc)--Stellenbosch University, 2008.
ENGLISH ABSTRACT: Alien trees, Pinus spp. and Eucalyptus spp., affect ants negatively in the Cape Floristic Region (CFR), a global biodiversity hotspot in South Africa. They reduce ant abundance and species richness, thus also changing ant assemblage structure. This is alarming, because almost 1300 species of plant species in the CFR are dispersed by certain indigenous ants, and thus there is concern for an indirect effect on indigenous plant assemblages. One of the most impacting ant species on seed dispersal is the invasive Argentine ant (Linepithema humile (Mayr)), which discards seeds outside its nest, where they do not germinate. Ten sites, on Vergelegen Wine Estate, were selected to explore these effects of alien plants. These varied from invaded to non-invaded sites. Each site consisted of six sampling points, which in turn consisted of four pitfall traps left out for seven days, during December 2005, February 2006, May 2006 and September 2006. Forty species of ant were sampled, and various analyses used to illustrate the comparative effects of plant invasion. All analytical methods showed that invasive alien plants had a significant impact on the abundance and richness of the ant species assemblage, by creating a dense canopy cover that changed the abiotic environment of the epigaeic ants’ habitat. Furthermore, increased alien tree invasion correlated significantly with Argentine ant abundances. The Argentine ant displaced Pheidole capensis and Camponotus spp., while it decreased the abundances of commonly-occurring indigenous ants, such as Lepisiota capensis and Plagiolepis spp. Displacement by the Argentine ant may be a result of indirect competition for food resources. The effects of invasive aliens are synergistic in that there is a cascade effects from initial plant invasions to subsequent animal invasion.
AFRIKAANSE OPSOMMING: Indringer bome, Pinus en Eucalyptus, affekteer miere op negatiewe wyse in die Kaap Florsitiese Streek (KFR), ‘n area in Suid Afrika van belang t.o.v. globale biodiversiteit. Hierdie uitheemse indringer bome verminder hulle hoeveelheid en spesies rykheid. Die bogenoemde is kommerwekkend omdat meer as 1300 plant spesies in the KFR versprei word deur miere. Die verandering in hoeveelheid en versameling van inheemse miere kan dus ernstige implikasies hê op die saad verspreiding van inheemse plant spesies. Een van die mees verwoestende effekte op saad verspreiding is veroorsaak deur die indringer Argentynse mier (Linepithema humile (Mayr)), wat sade neer werp buite hulle neste, waar hulle nie suksesvol kan ontkiem nie. Tien monsterings-tereine was geselekteer om die bogenoemde effekte te ondersoek op Vergelegen Landgoed. Hierdie het afgewissel van indringer tot skoon tereine. Elke terrein is op ses versamelings-plekke gemonster, met vier pitvalle, wat oopgelê het vir sewe dae gedurende Desember 2005, Februarie 2006, Mei 2006 en September 2006. 40 spesies van miere was gemonster. Indringer plante het ‚n betekenisvolle impak gehad het op die hoeveelheid en rykheid van die mier gemeenskappe, deur die skepping van ‚n dig baldakyn wat die abiotiese omgewing van die miere se habitat verander het. Die vermeerdering van indringer plante veroorsaak die vermeerdering van Argentyne miere. Kanonieke Mede-Respons Analise illustreer dat die Argentynse mier Pheidole capensis en Camponotus spp. verplaas het, terwyl dit ander inheemse mier getalle verminder het, soos Lepisiota capensis en Plagiolepis spp. Die verplasing deur die Argentynse mier mag die resultaat wees van indirekte wedywering vir hulpbronne. Die effekte van indringer species is dus sinergisties deur dat ‚n kaskade effek ontstaan vanaf plant tot dier indringer spesies.

This thesis is prepared in three parts; the first part is a study of the ant species of the southern Carnarvon Basin, which was undertaken in order to determine the patterns of ant species distribution in this arid zone area. The distribution patterns were looked at in terms of biogeographical regions and they demonstrated the transitional nature of this particular area. Recommendations to alter the border between the South-west Province and the Eremaean Province were supported. The next chapter of this thesis analysed ant species from long unburnt and burnt areas of three main vegetation types (two Triodia species grasslands and Acacia aneura woodlands) in the Gibson Desert Nature Reserve. This study was carried out to observe the recovery of ant populations after fire. The results provided further evidence that invertebrates are measurably impacted by fire in the arid zone. The final chapter is a comparison of these two arid zone studies with six other ant community studies from throughout Western Australia. It demonstrated the uniqueness of some arid zone sites as well as related each study to each other according to their ant communities.

In the last decades there has been a lot of interest in computational models and metaheuristics algorithms capable to solve combinatorial optimization problems. The recent trend is to define these algorithms taking inspiration by the observation of natural systems. In this thesis the Ant Colony System (ACS) is presented which has been inspired by the observation of real ant colonies. ACS is initially proposed to solve the symmetric and asymmetric travelling salesman problems where it is shown to be competitive with other metaheuristics. Although this is an interesting and promising result, it was immediately clear that ACS, as well as other metaheuristics, in many cases cannot compete with specialized local search methods. An interesting trend is therefore to couple metaheuristics with a local optimizer, giving birth to so-called hybrid methods. Along this line, the thesis investigates MACS-VRPTW (Multiple ACS for the Vehicle Routing Problem with Time Windows) and HAS-SOP: Hybrid Ant System for the Sequential Ordering Problem (SOP). In the second part the thesis introduces some modifications of the original ACS algorithm. These modifications are able to speed up the method and to make it more competitive in case of large problem instances. The resulting framework, called Enhanced Ant Colony System is tested for the SOP. Finally the thesis presents the application of ACS to solve real-life vehicle routing problems where additional constraints and stochastic information are included.
Doctorat en Sciences de l'ingénieur
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The Ant System is a new meta-heuristic method particularly appropriate to solve hard combinatorial optimization problems. It is a population-based, nature-inspired approach exploiting positive feedback as well as local information and has been applied successfully to a variety of combinatorial optimization problem classes. The Ant System consists of a set of cooperating agents (artificial ants) and a set of rules that determine the generation, update and usage of local and global information in order to find good solutions. As the structure of the Ant System highly suggests a parallel implementation of the algorithm, in this paper two parallelization strategies for an Ant System implementation are developed and evaluated: the synchronous parallel algorithm and the partially asynchronous parallel algorithm. Using the Traveling Salesman Problem a discrete event simulation is performed, and both strategies are evaluated on the criteria "speedup", "efficiency" and "efficacy". Finally further improvements for an advanced parallel implementation are discussed. (author's abstract)
Series: Report Series SFB "Adaptive Information Systems and Modelling in Economics and Management Science"

An appreciation of the role of mutualism is essential when studying ecology and evolution in most ecosystems. Information covering aspects of mutualistic interactions can serve as a complement to the somewhat one-sided perspective from the 1950’s and 60’s that is used when teaching biology. In this thesis I applied an in-depth approach in which variation in the interspecific interaction between Aphis fabae aphids and Lasius niger ants was studied both in the field and in the laboratory. An emphasis was put on studies spanning several consecutive aphid generations. This approach revealed important differences between ant tended aphids and those without ants. In the lab, I found an initial decrease in aphid adult size and reproductive investment in the first generations after the start of ant tending, which was followed by a recovery to the pre-tending situation after about four generations. Another laboratory experiment showed an increase in alate (winged aphid) production from exposure to aphid alarm pheromones, and an even stronger decrease in alate production from ant attendance, suggesting that ants have gained the upper hand in an evolutionary conflict over aphid dispersal. Results from a field experiment further emphasized the possibility of negative effects of ants on aphids, showing that ant-tended aphid colonies experienced a higher rate of parasitoid attacks, produced fewer alates and embryos in adult aphids. The thesis highlights the scope for variation in the net effect of the interaction for aphids, and argues that, depending on the environmental circumstances, the interaction may sometimes and perhaps even often not really be a case of mutualism.

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.

This research identifies and investigates major issues in inducing accurate and comprehensible fuzzy rules from datasets. A review of the current literature on fuzzy rulebase induction uncovers two significant issues: A. There is a tradeoff between inducing accurate fuzzy rules and inducing comprehensible fuzzy rules; and, B. A common strategy for the induction of fuzzy rulebases, that of iterative rule learning where the rules are generated one by one and independently of each other, may not be an optimal one. FRANTIC, a system that provides a framework for exploring the claims above is developed. At the core lies a mechanism for creating individual fuzzy rules. This is based on a significantly modified social insect-inspired heuristic for combinatorial optimisation -- Ant Colony Optimisation. The rule discovery mechanism is utilised in two very different strategies for the induction of a complete fuzzy rulebase: 1. The first follows the common iterative rule learning approach for the induction of crisp and fuzzy rules; 2. The second has been designed during this research explicitly for the induction of a fuzzy rulebase, and generates all rules in parallel. Both strategies have been tested on a number of classification problems, including medical diagnosis and industrial plant fault detection, and compared against other crisp or fuzzy induction algorithms that use more well-established approaches. The results challenge statement A above, by presenting evidence to show that one criterion need not be met at the expense of the other. This research also uncovers the cost that is paid -- that of computational expenditure -- and makes concrete suggestions on how this may be resolved. With regards to statement B, until now little or no evidence has been put forward to support or disprove the claim. The results of this research indicate that definite advantages are offered by the second simultaneous strategy, that are not offered by the iterative one. These benefits include improved accuracy over a wide range of values for several key system parameters. However, both approaches also fare well when compared to other learning algorithms. This latter fact is due to the rule discovery mechanism itself -- the adapted Ant Colony Optimisation algorithm -- which affords several additional advantages. These include a simple mechanism within the rule construction process that enables it to cope with datasets that have an imbalanced distribution between the classes, and another for controlling the amount of fit to the training data. In addition, several system parameters have been designed to be semi-autonomous so as to avoid unnecessary user intervention, and in future work the social insect metaphor may be exploited and extended further to enable it to deal with industrial-strength data mining issues involving large volumes of data, and distributed and/or heterogeneous databases.

This work is concerned with heuristic approaches to examination timetabling. It is demonstrated that a relatively new evolutionary method, the Ant System, can be the basis of a successful two-phase solution method. The first phase exploits ant feedback in order both to produce large volumes of feasible timetables and to optimise secondary objectives. The second phase acts as a repair facility where solution quality is improved further while maintaining feasibility. This is accomplished without increasing computational effort to unrealistic levels. The work builds on an existing implementation for the graph colouring problem, the natural model for examination scheduling. It is demonstrated that by adjusting the graph model to allow the accommodation of several side constraints as well incorporating enhancement techniques within the algorithm itself, the Ant System algorithm becomes very effective at producing feasible timetables. The enhancements include a diversification function, new reward functions and trail replenishment tactics. It is observed that the achievement of second-order objectives can be enhanced through a variety of means. A modified elitist strategy (ERF) significantly improves the performance of the Ant System due to the extra emphasis on second-order feedback. It is also shown that through the incorporation of the ERF, trail limits and, in particular, 19th century evolutionary theory the area of the solution space explored by the ants during the infancy of the search can be reduced. In addition, a good level of exploration is maintained as the search matures. This balance between exploration and exploitation is the main determinant of solution quality. The use of a repair facility, as is common practice with evolutionary algorithms, encourages fitter solutions. The interaction between Lamarckian evolution and searching in an extended neighbourhood through the graph theoretic concept of Kempe chains leads to better overall solutions.

Ant Colony Optimisation algorithms mimic the way ants use pheromones for marking paths to important locations. Pheromone traces are followed and reinforced by other ants, but also evaporate over time. As a consequence, optimal paths attract more pheromone, whilst the less useful paths fade away. In the Multiple Pheromone Ant Clustering Algorithm (MPACA), ants detect features of objects represented as nodes within graph space. Each node has one or more ants assigned to each feature. Ants attempt to locate nodes with matching feature values, depositing pheromone traces on the way. This use of multiple pheromone values is a key innovation. Ants record other ant encounters, keeping a record of the features and colony membership of ants. The recorded values determine when ants should combine their features to look for conjunctions and whether they should merge into colonies. This ability to detect and deposit pheromone representative of feature combinations, and the resulting colony formation, renders the algorithm a powerful clustering tool. The MPACA operates as follows: (i) initially each node has ants assigned to each feature; (ii) ants roam the graph space searching for nodes with matching features; (iii) when departing matching nodes, ants deposit pheromones to inform other ants that the path goes to a node with the associated feature values; (iv) ant feature encounters are counted each time an ant arrives at a node; (v) if the feature encounters exceed a threshold value, feature combination occurs; (vi) a similar mechanism is used for colony merging. The model varies from traditional ACO in that: (i) a modified pheromone-driven movement mechanism is used; (ii) ants learn feature combinations and deposit multiple pheromone scents accordingly; (iii) ants merge into colonies, the basis of cluster formation. The MPACA is evaluated over synthetic and real-world datasets and its performance compares favourably with alternative approaches.

This thesis examines two ant-based models: the first is a model of biological ants using mass recruitment; and the second is an ant-based search technique based on ants foraging using mass recruitment. Mass recruitment is the method by which foraging ants recruit other ants to food by the laying of pheromone trails. These models are developed as ordinary differential equation models. The analysis, in both cases, involves the construction of a. Lyapunov function and the examination of the equilibrium distributions of ants and pheromone. An analogy of thermodynamic ideal gas to foraging ants is applied in Chapter 4. This enables the analogue of the Helmholtz free energy to be proved to be a Lyapunov function. Thus an understanding of the distribution of ants as a function of the distribution of pheromone concentration is established. This enables the examination of the evolution of the pheromone distribution, which results in the discovery of the existence of three main foraging responses of a colony of ants: the individual ants explore independently; a weak network forms; or a strong network forms. A weak network consists of trails which are very tortuous, often bending, branching and interconnecting. A strong network consists of straight, unbranched trunk-trails. In addition, the effects of the individual ant behaviours, such as pheromone-laying rate, response to pheromone and turning behaviour, and the number of ants foraging on the trail pheromone concentrations and trail densities of these networks is determined. The result of this analysis is an understanding of the flexibility of the response of ant colonies to a changing environment. Chapter 5 examines the Ant System algorithm — an ant-based optimisation algorithm formulated for solving the travelling salesman problem. To do this a continuous analogue of this algorithm is constructed in which the ant densities are infinitesimally divisible. Examination of this analogue provides two previously unrecorded adaptations of this algorithm which improve its efficiency. These adaptations are to the probability of finding the optimal solution, and to the time taken in doing so. Results of numerical simulations are presented which illustrate these theoretical results. Finally the convergence properties of the algorithm are examined by the construction of a Lyapunov function. This analysis provides an understanding of the conditions required for convergence.