Showing papers in "CTIT technical reports series in 2008"

Runtime Monitoring of Metric First-order Temporal Properties

Abstract: We introduce a novel approach to the runtime monitoring of complex system properties. In particular, we present an online algorithm for a safety fragment of metric first-order temporal logic that is considerably more expressive than the logics supported by prior monitoring methods. Our approach, based on automatic structures, allows the unrestricted use of negation, universal and existential quantification over infinite domains, and the arbitrary nesting of both past and bounded future operators. Moreover, we show how to optimize our approach for the common case where structures consist of only finite relations, over possibly infinite domains. Under an additional restriction, we prove that the space consumed by our monitor is polynomially bounded by the cardinality of the data appearing in the processed prefix of the temporal structure being monitored.

A visual method for robot proxemics measurements

Abstract: Human interaction knows many non-verbal aspects. The use of space, among others, is guided by social rules. Not conforming to these rules may cause discomfort or even mis- communication. If robots are to interact with people, they must follow similar rules. The current work tries to identify factors that influence human preferred interaction distance in conversation-like interaction. For the measurement of interaction distances an accurate and objective visual method is presented. In this method, the researcher does influence the results by disturbing the interaction. It is found that subjects choose interaction distances com- parable to those in human interaction. Variations are mostly explained by subject age and, depending on age, by gender or robot appearance. This is the first time, to our knowledge, that a clear age and gender effect is found in human-robot interaction-distance.

Spatially adaptive photographic flash

Abstract: Using photographic flash for candid shots often results in an unevenly lit scene, in which objects in the back appear dark We describe a spatially adaptive photographic flash system, in which the intensity of illumination varies depending on the depth and reflectivity of features in the scene We adapt to changes in depth using a single-shot method, and to changes in reflectivity using a multi-shot method The single-shot method requires only a depth image, whereas the multi-shot method requires at least one color image in addition to the depth data To reduce noise in our depth images, we present a novel filter that takes into account the amplitude-dependent noise distribution of observed depth values To demonstrate our ideas, we have built a prototype consisting of a depth camera, a flash light, an LCD and a lens By attenuating the flash using the LCD, a variety of illumination effects can be achieved

The distribution and status of Marine Turtle nesting in the Northern Territory

Abstract: The Northern Territory (hereafter referred to as NT) coast and coastal wetlands are vast and remote, creating particular challenges for documenting wildlife distribution and abundance. Prior to 1990 there had been little systematic or comprehensive attempts to inventory the biodiversity of these systems. From 1990 to 2004 (and incidentally thereafter) numerous aerial and ground surveys were conducted by RC along the NT coastline and throughout the near-coastal wetlands to locate and document the distribution and status of selected wildlife. These surveys focused on aquatic birds (e.g. seabirds, shorebirds and waterbirds), marine reptiles and marine mammals. During this time around 70 000 separate records totalling around 5.6 million individuals were made in the survey area. A series of four reports detailing the distribution and status of the aquatic birds has been completed. This fifth report in the series details records collected on marine turtle nesting. Between 1990 and 2004 in excess of 7 000 records were collected relating to marine turtle nesting around the NT coast. Marine turtles were recorded nesting around much of the mainland coast and on the many islands with sandy beaches. Most of the high density areas were located on offshore islands, with only a few high density sites found on the mainland, where egg predation was generally much higher. Four species of marine turtle were regularly recorded nesting in the NT. These were the Flatback Turtle (Natator depressus), Green Turtle (Chelonia mydas), Hawksbill Turtle (Eretmochelys imbricata) and Olive Ridley Turtle (Lepidochelys olivacea). Nesting densities varied among species at different sites. Of the four marine turtle species to regularly nest in the NT, Flatback Turtles were clearly recorded as the most widespread nesting species. This species nested on nearly all beaches where any marine turtle nesting occurred, either on their own or with other species. Flatback Turtles and Green Turtles were the two most abundant nesting species. The range of Green Turtle nesting was much more geographically restricted (mostly occurring along the eastern NT coast) but where they did nest, they often did so in very high numbers. The combined major sites of Green Turtle nesting in north eastern Arnhem Land are likely to be of international significance. Olive Ridley Turtles were the second most widespread nesting species after Flatbacks, but over most of their range (which included little of the western coast of the NT) they nested in low numbers. However, on some beaches (e.g. along the northern coast of the Tiwi Islands and some islands in north eastern Arnhem Land) they nested in nationally significant numbers. Hawksbill Turtles were the least widespread of the four most frequent nesting species. Their nesting was concentrated on islands in north eastern Arnhem Land and around Groote Eylandt. The combined nesting of the major Hawksbill Turtle nesting sites in this area is likely also to be of international significance. Leatherback Turtle (Dermochelys coriacea) nesting was confirmed from only one site (on Cobourg Peninsula) although there are a few anecdotal reports of occasional nesting from a small number of other areas. Although Loggerhead Turtles (Caretta caretta) are recorded in NT waters, they were not confirmed nesting anywhere in the NT. Several parts of the NT coast can now be considered as internationally or nationally important nesting areas for marine turtles. The most important areas located during these surveys are: Turtle Point in Joseph Bonaparte Gulf, Bare Sand and Quail Islands near Darwin, the south west of Bathurst Island, a number of beaches along the northern coastline of Melville Island, the Smith Point area of Cobourg Peninsula, the islands to the north and east of Croker Island, the Goulburn Islands, NW Crocodile Island, many of the outer islands of the numerous island chains off north eastern Arnhem Land, the mainland coast and islands between Cape Arnhem and Blue Mud Bay, the eastern part of Groote Eylandt and its associated islands and some of the outer islands in the Sir Edward Pellew Group. Most of these sites are on Aboriginal Land. Although some limitations remain due to the largely unsystematic way the data were collected, the outcome of over 15 years of surveys is that the most important areas, and the timing of nesting, have been identified for the four major nesting species of marine turtle in the NT. The collection and collation of this significant number of marine turtle nesting records has provided the baseline information for future research and management of marine turtles across the NT. As with the many other important fauna sites around the NT coast (documented in previous reports in this series), the significant marine turtle nesting sites are still in a fairly unique position. Many of these sites are still not subject to the pressures associated with large human populations. As such, we should be able to be proactive and ensure the long term security of these sites before problems arise rather than have to seek reactive remedies after damage has occurred. The next step in the process to protect the turtles and their nesting habitat in the NT should be to establish monitoring programs for selected sites and the subsequent drafting of management plans/programs for species and areas. These need to link in with other States, the Commonwealth and regional government plans, and work in with other groups such as indigenous rangers in remote coastal communities. The NT's marine protected areas program and the Commonwealth 'Work on Country' programs supporting Indigenous people to manage resources can provide vehicles for such cooperative programs.

Formalizing Proof-Transforming Compilation of Eiffel Programs

Abstract: The execution of mobile code can produce unexpected behavior, which may comprise security and correctness of a software system. Proof-Carrying Code allows one to execute mobile code in a safe way by checking a formal proof before the code is executed. However, automatic generation of proofs works only for basic safety properties such as type safety. To apply PCC to functional correctness properties, we propose to verify the source program interactively and then to translate the proof to bytecode. This proof translation is relatively straightforward if the source and target language are similar, such as Java and Java bytecode, but poses challenges for more complex translations. In this paper, we present a prooftransforming compiler for a subset of Eiffel to the .NET CIL. In particular, we show how the non-trivial translations of multiple inheritance and Eiffel’s exceptions can be handled.

A Cost-Effective Atomic Force Microscope for Undergraduate Control Laboratories; ; Technical Report;

Abstract: This paper presents a simple, cost-effective and robust Atomic Force Microscope (AFM), which has been purpose designed and built for use as a teaching aid in undergraduate controls labs. The guiding design principle is to have all components be open and visible to the students and as a result, the inner functioning of the microscope is clear to see. All but one part are off the shelf, and assembly time is less than two days, which makes the microscope a robust instrument, that is readily handled by the students with little chance of damage. While the scanning resolution is nowhere near that of a commercial instrument, it is more than sufficient to take interesting scans of micrometer-scaled objects.

Formalizing Proof-Transforming Compilation of Eiffel Programs; ; Technical Report;

Abstract: The execution of mobile code can produce unexpected behavior, which may comprise secu- rity and correctness of a software system. Proof-Carrying Code allows one to execute mobile code in a safe way by checking a formal proof before the code is executed. However, automatic generation of proofs works only for basic safety properties such as type safety. To apply PCC to functional correctness properties, we propose to verify the source program interactively and then to translate the proof to bytecode. This proof translation is relatively straightforward if the source and target language are similar, such as Java and Java byte- code, but poses challenges for more complex translations. In this paper, we present a proof- transforming compiler for a subset of Ei®el to the .NET CIL. In particular, we show how the non-trivial translations of multiple inheritance and Eiffel's exceptions can be handled.

Resolving the Unexpected in Elections: Election Officials' Options

Abstract: This paper seeks to assist election officials and their lawyers in effectively handling the technical issues that can be difficult to understand and analyze, allowing them to protect themselves and the public interest from unfair accusations, inaccuracies in results, and conspiracy theories. The paper helps to empower officials to recognize which types of voting system events and indicators need a more structured analysis and what steps to take to set up the evaluations (or forensic assessments) using computer experts.

A technical survey on medium access control and routing protocols in wireless sensor networks for the active aircraft

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A generalised finite domain constraint solver for SWI-Prolog

Abstract: In this paper we describe a new constraint solver over finite domains that has recently been included in the SWI-Prolog distribution 1. Our solver generalises finite domain constraint solving towards unbounded domains, and thus enables a uniform approach to integer arithmetic and constraints. We ensure termination of all predicates, which facilitates termination proofs of constraint logic programs. The solver is written in Prolog and can be quite easily ported to other systems.

Interaction of market and credit risk: an analysis of inter-risk correlation and risk aggregation

Abstract: Die Berechnung einer bankweit aggregierten Risikokennzahl (normalerweise ausgedruckt durch das okonomische Kapital) ist ein auserst wichtiger Bestandteil eines modernen Risikocontrollings and als solches von besonderer Bedeutung fur bankinterne als auch regulatorische Zwecke. Eine wichtige Frage dabei betrifft die Behandlung von risikoreduzierenden Diversifikationseffekten, die als Folge der Geschaftsstrategie einer Bank (z.B. durch Produktdiversifikation oder geografische Diversifikation) auftreten konnen. Solche Diversifikationseffekte stellen einen Wettbewerbsvorteil dar, den Banken deshalb bei der Bestimmung ihrer Kapitaladaquanz mit einbeziehen wollen. Auch die Bankenaufsicht erkennt in ihren Ausfuhrungen uber die bankinternen Kapitalbeurteilungsverfahren nach den Grundsatzen der zweiten Saule von Basel II die Existenz von Diversifikationseffekten an. Bei der praktischen Berechnung des Diversifikationseffektes unterscheidet man oft zwischen Intrarisiko- und Interrisikodiversifikation. Letztere behandelt die Diversifikation innerhalb einer Risikoart (z.B. Markt- oder Kreditrisiko), wohingegen Interrisiko-Diversifikation die Diversifikation zwischen verschiedenen Risikoarten beschreibt und meist durch eine Interrisiko-Korrelationsmatrix erfasst wird.

Developing topology discovery in Event-B*

Abstract: We present a formal development in Event-B of a distributed topology discovery algorithm. Distributed topology discovery is at the core several routing algorithms and is the problem of each node in a network discovering and maintaining information on the network topology. One of the key challenges in developing this algorithm is specifying the problem itself.We provide a specification that includes both safety properties, formalizing invariants that should hold in all system states, and liveness properties that characterize when the system reaches stable states. We specify these by appropriately combining invariants, event refinement, and proofs of event convergence and deadlock freedom. The combination of these features is novel and should be useful for formalizing and developing other kinds of semi-reactive systems, which are systems that react to, but do not modify, their environment.

Discovery of Network Properties with All-Shortest-Paths Queries

Abstract: We consider the problem of discovering properties (such as the diameter) of an unknown network G(V,E) with a minimum number of queries. Initially, only the vertex set V of the network is known. Information about the edges and non-edges of the network can be obtained by querying nodes of the network. A query at a node q ∈ V returns the union of all shortest paths from q to all other nodes in V . We study the problem as an online problem – an algorithm does not initially know the edge set of the network, and has to decide where to make the next query based on the information that was gathered by previous queries. We study how many queries are needed to discover the diameter, a minimal dominating set, a maximal independent set, the minimum degree, and the maximum degree of the network. We also study the problem of deciding with a minimum number of queries whether the network is 2-edge or 2-vertex connected. We use the usual competitive analysis to evaluate the quality of online algorithms, i.e., we compare online algorithms with optimum offline algorithms. For all properties except maximal independent set, 2-vertex connectivity and minimum/maximum degree, we present and analyze online algorithms. Furthermore we show, for all the aforementioned properties, that “many” queries are needed in the worst case. As our query model delivers more information about the network than the measurement heuristics that are currently used in practise, these negative results suggest that a similar behavior can be expected in realistic settings, or in more realistic models derived from the all-shortest-paths query model.

A Cost-Effective Atomic Force Microscope for Undergraduate Control Laboratories

Abstract: This paper presents a simple, cost-effective and robust atomic force microscope (AFM), which has been purposely designed and built for use as a teaching aid in undergraduate controls labs. The guiding design principle is to have all components be open and visible to the students, so the inner functioning of the microscope has been made clear to see. All of the parts but one are off the shelf, and assembly time is generally less than two days, which makes the microscope a robust instrument that is readily handled by the students with little chance of damage. While the scanning resolution is nowhere near that of a commercial instrument, it is more than sufficient to take interesting scans of micrometer-scale objects. A survey of students after their having used the AFM resulted in a generally good response, with 80% agreeing that they had a positive learning experience.

Sistemas de gestão de processos de negócios : desafios e oportunidades

Abstract: Resumo: Esse relatorio resume o que foi apresentado e discutido no workshop empresarial intitulado "Sistemas de Gestao de Processos de Negocios", durante o ENEGEP 2007 em Foz do Iguacu-PR. Os sistemas de gestao de processos de negocios visam facilitar a execucao e gerencia dos processos de negocios nas empresas. A implementacao e manutencao de tais sistemas envolve um ciclo com quatro fases: (i) (re-) modelagem dos processos de negocios; (ii) configuracao desses modelos para um determinado sistema; (iii) execucao dos processos em ferramentas de apoio; e, (iv) analise de tais execucoes. Nesse contexto, dois problemas sao fundamentais. O primeiro e como integrar os diferentes processos de negocios intra- e/ou inter-organizacionais. O segundo e como analisar as execucoes desses processos de negocios de forma a detectar eventuais pontos de otimizacao, como realizar auditorias dos processos automaticamente, entre outros. Note que o primeiro problema esta relacionado as tres primeiras fases da implementacao dos sistemas de gerenciamento, enquanto o segundo envolve a fase de analise. Nesse sentido, esse documento contem nossas experiencias na solucao de tais problemas. Para a parte de modelagem e gerenciamento, sao apresentadas tecnicas de modelagem e gerencia de workflow incluindo experiencias em contrato eletronico, que determinam como diferentes empresas/departamentos negociam a execucao de processos. Alem disso, mostram-se algumas vantagens na inclusao de parâmetros de qualidade de servico para descoberta de servicos que melhor atendam os requisitos de consumidores. Para a parte de analise, o foco e nas tecnicas de mineracao de processos (www.processmining.org) que fornecem feedbacks sobre diferentes perspectivas (fluxo de atividades, organizacao, etc) dos processos de negocios. Como o objetivo final desse documento e estimular a cooperacao entre industria e academia, as pesquisas apresentadas sao concretamente ilustradas atraves de estudos de caso.