901 resultados para Local-Global topics
Resumo:
Sustainability is the aim of forest management and forest regulation in many countries. Accordingly, forest management has been steered towards more environmentally friendly methods and new regulatory instruments have been introduced. At the same time, wood trade and forest industry have become a global business. Even if the importance of national forest legislation has not decreased, it has been widely acknowledged that national regulation of forest management is no longer sufficient. The movement of goods does not acknowledge boundaries, even though most negative environmental and social consequences stay in the country of origin of wood and other raw materials. As a partial solution to this dilemma, different kinds of regulations have been developed. Various forest certification schemes and wood trade regulation in the EU (995/2010) are examples of efforts to prevent illegal logging and unsustainable forestry. The Finland-based forest industry is to a varying extent dependent on wood trade from Russia. Especially in the 1990‟s, ethical questions concerning import of wood from Russian old growth forests near the Finnish border were widely discussed. Consequently, forest industry enterprises have developed systems to trace the origin of wood and to buy certified wood from Russia. The aim of the research has been to evaluate Finnish and Russian forest regulations in order to investigate what kind of forest management these regulations enhance, and to what extent ecologically sustainable forest management has been integrated into different forms of regulation. I have examined Finnish and Russian forest regulation in four separate articles based on the topics of the Russian Forest Code, forest certification and other voluntary forest protection measures in Russia, Finnish forest certification and Finnish forest legislation. One objective has been to analyse the roles voluntary forest certification plays in promoting sustainable forest management in different countries. In my research, I have mainly concentrated on ecological sustainability and protection of biodiversity, although other aspects of sustainable forest management have been touched upon in different articles. In the following I shall conclude the findings of my research. When the current Russian Forest Code (2006) was being adopted, the main emphasis was not on ecological issues, but on reorganizing forest governance. The role of ecological requirements was even slightly diminished during the legislative reform. There are, nevertheless, still stipulations aiming at ecological sustainability, such as the division of forests into different forest management categories and various protection zones. In 2000, FSC forest certification arrived in Russia, at present covering already 28 million hectares of forests. The PEFC scheme is now in use as well, but to a much lesser extent. If properly implemented, Russian forest certification schemes clearly improve the level of ecological and social sustainability of forestry in Russia. Certification criteria, however, are partly in conflict with the Russian forest legislation and certified enterprises have been forced to pay fines or to negotiate with forest authorities. This clearly indicates that even if Russian forest legislation has otherwise been liberalized to a certain extent, some significant paternalism still exists. Voluntary, hands-on biodiversity protection measures are not valued, and they are not part of the official protection policies as in many other countries. However, there have been some regional solutions to this dilemma. In the Republic of Karelia forest authorities have approved a set of forest biodiversity protection rules created by a local NGO and a forest industry enterprise. By following these local rules, an enterprise can avoid fines for protection measures. The current Finnish Forest Act was adopted in 1996. It brought forest legislation into a new era as some ecological aspects were integrated into forest legislation. The various soft-law forest management recommendations further increased the level of biodiversity protection. My evaluation of the overall legitimacy of the Finnish forest legislation and forest management paradigm revealed, however, several problematic issues. As part of this study I analysed the history of the current forest management paradigm. This analysis revealed the path dependency which still hinders the protection of biodiversity and clearly decreases the general legitimacy of forest management. Due to several historical reasons only even-structured forest management based on clear cuts has for decades been officially approved in Finland. Due to increasing demands of forest owners the legislation is finally being revised. Yet, the official approval of uneven-structured forest management would not be enough to fully improve ecological, social and cultural legitimacy. The latest ecological theories and knowledge of endangered species should be taken into account in the on-going reform of forest legislation as well as the modernisation. Forest legislation is one of the very few spheres of Finnish environmental legislation where openness and participation are still considered a threat. The first Finnish forest certification scheme, PEFC, was established in 2000. It now covers more than 20 million hectares, about 95% of the forests in Finland. PEFC Finland does not require a higher level of biodiversity protection than the recommendations by Tapio (the Development Centre for Forestry), but certification has unified forest management practices and requires more protection measures than mere forest legislation. The study suggests that in Finland PEFC has not functioned as an instrument which would substantially improve the level of forest management. Rather it has supported the status quo of the forest sector. While the ecological and social responsibility of Finland-based forest corporations was one impetus for this research, I want to conclude that there are problems related to forest legislation and non-state regulation in both Finland and Russia. If an enterprise buying wood from Russia buys only certified wood, and carefully avoids wood coming from high conservation value forests that are either ecologically or socially valuable, it can be claimed to be as sustainably produced as in Finland. However, there must be continuous scrutiny of the circumstances. In Russia, the level of the compliance of certification criteria varies considerably, and there are vast unprotected invaluable forest areas. The utilisation of these areas should not be based on short-sighted decisions or lack of consensus among stakeholders.
Resumo:
OBJETIVO: investigar o impacto da recorrência local no prognóstico de pacientes com câncer de mama em estágio inicial tratado com cirurgia conservadora. MÉTODO: foi realizado estudo de coorte retrospectivo incluindo 192 pacientes com câncer de mama em estágio inicial submetidas a tratamento conservador. Utilizando critérios clínicos e patológicos (tempo para recorrência, local da recorrência e tipo histológico) classificamos as pacientes em três grupos. O grupo de recorrência local verdadeira (RLV), o grupo de novo tumor primário (NP) e o grupo livre de recorrência local (LRL). Foi comparada a evolução entre os diferentes grupos. RESULTADOS: menor idade e uma maior proporção de pacientes na pré-menopausa foram observas no grupo NP. A presença de RLV foi o mais importante fator prognóstico sendo que 40% das pacientes deste grupo desenvolveram doença metastática sincrônica à recorrência local. Doença metastática ocorreu em 28,5% e 4,7% nos grupos NP e LRL, respectivamente (p< 0,0001). A taxa de sobrevida global em cinco anos foi de 75% no grupo RLV, 100% no grupo NP e 98,2% no grupo LRL (p< 0,0001). Tipo histológico, margens cirúrgicas, metástase em linfonodos axilares e expressão de receptores hormonais não foram preditores de recorrência local. Pacientes que não foram submetidas a hormonioterapia adjuvante e a idade foram os mais importantes fatores preditores de recorrência local. CONCLUSÃO: recorrência local verdadeira é um fator prognóstico em pacientes com câncer de mama inicial tratado com cirurgia conservadora. A idade é o mais importante fator na recorrência local neste grupo de pacientes. O alto risco recorrência local nestas pacientes é um fator limitante da cirurgia conservadora.
The demand for global student talent: Capitalizing on the value of university-industry collaboration
Resumo:
The university sector in Europe has invested money and effort into the internationalization of higher education. The benefits of internationalizing higher education are fuelled by changing global values, choices and practices. However, arguments that serve the internationalization of higher education tend to stress either local organizational or individual interests; seldom do they emphasize the societal benefits. This dissertation investigates how collaboration between university and industry facilitates a shift in thinking about attracting and retaining global student talent, in terms of co-creating solutions to benefit the development of our knowledge society. The macro-structures of the higher education sector have the tendency to overemphasize quantitative goals to improve performance verifiability. Recruitment of international student talent is thereby turned into a mere supply issue. A mind shift is needed to rethink the efficacy of the higher education sector with regard to retaining foreign student talent as a means of contributing to society’s stock of knowledge and through that to economic growth. This thesis argues that academic as well as industrial understanding of the value of university-industry collaboration might then move beyond the current narrow expectations and perceptions of the university’s contribution to society’s innovation systems. This mind shift is needed to encourage and generate creative opportunities for university-industry partnerships to develop sustainable solutions for successful recruitment of foreign student talent, and thereby to maximize the wealth-creating potential of global student talent recruitment. This thesis demonstrates through the use of interpretive and participatory methods, how it is possible to reveal new and important insights into university-industry partnering for enhancing attraction and retention of global student talent. It accomplishes this by expressly pointing out the central role of human collaborative experiencing and learning. The narratives presented take the reader into a Finnish and Dutch universityindustry partnering environment to reflect on the relationship between the local universities of technology and their operational surroundings, a relationship that is set in a context of local and global entanglements and challenges.
Resumo:
OBJETIVO: avaliar a taxa de recorrência local, regional e a distância de nova técnica cirúrgica para tratamento conservador do câncer de mama de estádio inicial. A técnica é baseada na ressecção segmentar com dissecção axilar e preservação de pele por incisão periareolar única. MÉTODOS: cento e dezenove pacientes com câncer de mama de estádio I e II foram incluídas neste estudo. O grupo estudo foi constituído por 57 pacientes que se submeteram à cirurgia pela técnica proposta e 62 pacientes submetidas a quadrantectomia clássica constituíram o grupo controle. A radioterapia pós-operatória e o boost foram realizados em ambos os grupos. A média de seguimento foi de 50,1 meses para o grupo estudo e 51,2 para o grupo controle. As taxas de recidiva, sobrevida global e sobrevida livre de doença foram analisadas e comparadas entre os dois grupos. RESULTADOS: a taxa de recidiva local no período foi de 3,5% para o grupo estudo e 4,8% para o grupo controle. Não houve diferença significativa entre os grupos nas taxas de sobrevida livre de doença e sobrevida global. CONCLUSÕES: a técnica de ressecção segmentar com dissecção axilar por incisão única periareolar, preservando pele, não mostrou diferença, em relação à quadrantectomia clássica, nas taxas de recidiva, sobrevida global e sobrevida livre de doença.
Resumo:
In this Master’s Thesis a global transport packaging guideline for selected business areas was compiled for the Fiskars the company, which provides branded consumer goods for home, garden and outdoor use. The business areas included were Home and Garden business areas. The aim of the guideline was to be a comprehensive guide for the suppliers, product development, operations and external vendors of the company. The guideline consists of written instructions, tables and illustrations that provide useful information for players working with transport packages from sourcing through to shipments. As the role of corporate responsibility and sustainability has grown, a part of responsible manufacturing strategy includes using materials that are re-usable, recyclable or recoverable as energy or through composting. Hence packaging waste management implementations of different regions were also inspected. The resulting guide covers a range of topics concerning packaging and its transport. The topics include legal requirements, restricted materials and substances, preferred materials, markings, labeling of boxes, logistics and distribution center requirements, physical testing and an inspection checklist.
Resumo:
Tämän Pro Gradu -tutkimuksen tavoite on Filippiineillä toimivan kohdeorganisaation sisäisen HR Shared Services palvelukeskuksen kokeman henkilöstön vaihtuvuuden erityispiirteiden sekä syiden ymmärtäminen. Tätä kautta pyritään hahmottamaan myös sopivia vaihtuvuuden hallintakeinoja organisaatiotasolla. Tapaustutkimus toteutettiin laadullisen tutkimuksen keinoja ja sekundaarista lähtödataa käyttäen. Tutkimustulokset osoittivat, että kohdeorganisaatio paini useiden toimiala- ja maakohtaisten vaihtuvuuden tekijöiden lisäksi muutamien organisaatiokohtaisten haasteiden kanssa, jotka heijastuivat sen kokemaan työvoiman vaihtuvuuteen. Yksikön tulee muun muassa panostaa sisäisiin urakehitysmahdollisuuksiin sekä johtajien ja uusien työntekijöiden koulutukseen. Suuri osa löydetyistä vaihtuvuuden syistä on ainakin osin organisaation hallittavissa ja tätä kautta saatiin luotua lista suositelluista toimenpiteistä, joilla kohdeorganisaatio voi pyrkiä hallitsemaan henkilöstönsä vaihtuvuutta.
Resumo:
This qualitative study has started from the interest to examine how the reality of crosscultural encounters is presented in the global business press. The research paper emphasizes different ways to classify culture and cross-cultural competency, both from the point of view of individuals and organizations. The analysis consists of public discourses, where cross-cultural realities are created through different persons, stories and contexts For data collection, a comprehensive database search was performed and 10 articles from the widely known worldwide business magazine The Financial Times were chosen as the data for the study paper. For the functions of addressing the research study questions, Thematic Content Analysis (TCA) and also Discourse Analysis (DA) are utilized, added with the continuous comparison method of grounded theory in the formation of the data.The academic references consist of literary works and articles presenting relevant concepts, creating a cross-cultural framework, and it is designed to assist the reader in the navigation through the topics of culture and cross-cultural competency. The repertoires were formed from the data and following, the first repertoire is contrast difference between home and target culture that the individual was able to discern. As a consequence of the first repertoire, the companies then offer cultural training to their employees to prepare them to situations of increasing levels of cultural variation. The third repertoire is increased awareness of other cultures, which is conveyed as a result of cultural training and contextual work experience. The fourth repertoire is globalization as an international business environment, where the people in the articles perform their job functions. It is stated in the conclusions that the representations emphasize Western values and personal traits in leadership.
Resumo:
The purpose of this paper is, first, to investigate the interconnections of substantive freedoms, which are indispensable for every individual to “lead the kind of lives they have reason to value” (Sen, 1999b, p.10,18), and which have legitimate and ethical reasons to be publicly secured, second, to investigate a conception of public-provision unit that embodies “the right to well-being freedom”, and a conception of decision-making unit that corresponds to it, based on the perspective of Sen’s capability theory and its extension, comparing with that of Rawls’ Theory of Justice and A Law of People. If we intend to construct such a public-provision unit, which conducts redistribution as a whole, and which receives every individual who cannot belong to any fixed local group, what kind of a body should we assume as a public-provision unit? And further, what kind of a body should we assume as a decision-making unit, which is responsible for deciding or revising the basic conceptions of public provision unit?
Resumo:
L’intégration des TIC a connu un essor considérable dans les dernières années et des chercheurs à travers le monde y accordent une importance sans cesse croissante ; le sujet des TIC en éducation est ainsi répandu au sein des écrits depuis maintenant plusieurs années (Istance & Kools, 2013; Storz & Hoffman, 2013). Dans un monde où les technologies sont omniprésentes dans la plupart des sphères d’activités, il ne s’agit plus de savoir si les technologies doivent être intégrées dans les activités d’enseignement et d’apprentissage, mais bien de quelle façon elles doivent l’être. Comme les TIC présentent de nombreux avantages, notamment en ce qui concerne la motivation scolaire et la réduction du fossé numérique, les différents intervenants du monde de l’éducation sont généralement conscients de l’importance de bien utiliser les technologies de l’information et de la communication (TIC) en éducation, mais ne savent pas toujours par où commencer. La présente recherche s’intéresse à une forme particulière d’intégration des TIC en éducation, soit les projets portables. Les projets portables se différencient par le fait que l’enseignant et chaque élève disposent de leur propre ordinateur portable dans le but d’une utilisation pédagogique. Cette thèse de doctorat tente de détailler, à travers un langage clair et accessible, les défis qu’il est possible de rencontrer à l’intérieur de tels projets, de même que ce qui peut être fait pour en limiter les impacts. En vue de déterminer les conditions pouvant favoriser le succès global des projets portables au Québec, voire ailleurs, une recension des écrits exhaustive a permis de relever quatre catégories de facteurs principales dans lesquelles l’ensemble des défis identifiés semblent pouvoir être classés : les facteurs relatifs à la gestion du projet, les facteurs internes à l’enseignant, les facteurs relatifs au cadre de travail de même que les facteurs relatifs à l’infrastructure et au matériel. Ces diverses catégories de facteurs sont abordées en détails à l’intérieur du cadre théorique de cette thèse de doctorat. En vue d’atteindre les objectifs, un questionnaire a été mis au point et plus de 300 enseignants d’une commission scolaire où a lieu un projet portable à grand déploiement y ont répondu. Les données de nature mixte (données quantitatives et qualitatives) ont été analysées à l’aide de logiciels spécialisés et ceci a permis de vérifier la pertinence des éléments rencontrés dans la recension des écrits, de même que d’en découvrir de nouveaux. Il a été trouvé que de nombreux défis sont susceptibles d’être rencontrés. Les plus importants ont trait à la qualité du matériel utilisé, à l’importance de la formation des enseignants relativement aux TIC, et à l’importance de mettre au point une vision claire assurant la pleine adhésion des enseignants. Il a aussi été déterminé que l’enseignant doit pouvoir accéder à un soutien pédagogique ainsi qu’à un soutien technique facilement. Enfin, il a été découvert que la nature des projets à grand déploiement fait en sorte qu’il importe de porter une attention particulière aux besoins locaux des enseignants, qui peuvent varier selon le contexte de travail de ceux-ci.
Resumo:
Cette thèse de doctorat consiste en trois chapitres qui traitent des sujets de choix de portefeuilles de grande taille, et de mesure de risque. Le premier chapitre traite du problème d’erreur d’estimation dans les portefeuilles de grande taille, et utilise le cadre d'analyse moyenne-variance. Le second chapitre explore l'importance du risque de devise pour les portefeuilles d'actifs domestiques, et étudie les liens entre la stabilité des poids de portefeuille de grande taille et le risque de devise. Pour finir, sous l'hypothèse que le preneur de décision est pessimiste, le troisième chapitre dérive la prime de risque, une mesure du pessimisme, et propose une méthodologie pour estimer les mesures dérivées. Le premier chapitre améliore le choix optimal de portefeuille dans le cadre du principe moyenne-variance de Markowitz (1952). Ceci est motivé par les résultats très décevants obtenus, lorsque la moyenne et la variance sont remplacées par leurs estimations empiriques. Ce problème est amplifié lorsque le nombre d’actifs est grand et que la matrice de covariance empirique est singulière ou presque singulière. Dans ce chapitre, nous examinons quatre techniques de régularisation pour stabiliser l’inverse de la matrice de covariance: le ridge, spectral cut-off, Landweber-Fridman et LARS Lasso. Ces méthodes font chacune intervenir un paramètre d’ajustement, qui doit être sélectionné. La contribution principale de cette partie, est de dériver une méthode basée uniquement sur les données pour sélectionner le paramètre de régularisation de manière optimale, i.e. pour minimiser la perte espérée d’utilité. Précisément, un critère de validation croisée qui prend une même forme pour les quatre méthodes de régularisation est dérivé. Les règles régularisées obtenues sont alors comparées à la règle utilisant directement les données et à la stratégie naïve 1/N, selon leur perte espérée d’utilité et leur ratio de Sharpe. Ces performances sont mesurée dans l’échantillon (in-sample) et hors-échantillon (out-of-sample) en considérant différentes tailles d’échantillon et nombre d’actifs. Des simulations et de l’illustration empirique menées, il ressort principalement que la régularisation de la matrice de covariance améliore de manière significative la règle de Markowitz basée sur les données, et donne de meilleurs résultats que le portefeuille naïf, surtout dans les cas le problème d’erreur d’estimation est très sévère. Dans le second chapitre, nous investiguons dans quelle mesure, les portefeuilles optimaux et stables d'actifs domestiques, peuvent réduire ou éliminer le risque de devise. Pour cela nous utilisons des rendements mensuelles de 48 industries américaines, au cours de la période 1976-2008. Pour résoudre les problèmes d'instabilité inhérents aux portefeuilles de grandes tailles, nous adoptons la méthode de régularisation spectral cut-off. Ceci aboutit à une famille de portefeuilles optimaux et stables, en permettant aux investisseurs de choisir différents pourcentages des composantes principales (ou dégrées de stabilité). Nos tests empiriques sont basés sur un modèle International d'évaluation d'actifs financiers (IAPM). Dans ce modèle, le risque de devise est décomposé en deux facteurs représentant les devises des pays industrialisés d'une part, et celles des pays émergents d'autres part. Nos résultats indiquent que le risque de devise est primé et varie à travers le temps pour les portefeuilles stables de risque minimum. De plus ces stratégies conduisent à une réduction significative de l'exposition au risque de change, tandis que la contribution de la prime risque de change reste en moyenne inchangée. Les poids de portefeuille optimaux sont une alternative aux poids de capitalisation boursière. Par conséquent ce chapitre complète la littérature selon laquelle la prime de risque est importante au niveau de l'industrie et au niveau national dans la plupart des pays. Dans le dernier chapitre, nous dérivons une mesure de la prime de risque pour des préférences dépendent du rang et proposons une mesure du degré de pessimisme, étant donné une fonction de distorsion. Les mesures introduites généralisent la mesure de prime de risque dérivée dans le cadre de la théorie de l'utilité espérée, qui est fréquemment violée aussi bien dans des situations expérimentales que dans des situations réelles. Dans la grande famille des préférences considérées, une attention particulière est accordée à la CVaR (valeur à risque conditionnelle). Cette dernière mesure de risque est de plus en plus utilisée pour la construction de portefeuilles et est préconisée pour compléter la VaR (valeur à risque) utilisée depuis 1996 par le comité de Bâle. De plus, nous fournissons le cadre statistique nécessaire pour faire de l’inférence sur les mesures proposées. Pour finir, les propriétés des estimateurs proposés sont évaluées à travers une étude Monte-Carlo, et une illustration empirique en utilisant les rendements journaliers du marché boursier américain sur de la période 2000-2011.
Resumo:
The Tropospheric Biennial Oscillation (TBO), a major interannual variation phenomenon in the Indo-Pacific region, is the result of strong ocean-atmosphere coupling over the Asian-Australian monsoon area. Along with other meteorological and oceanographic parameters, the tropical circulation also exhibits interannual oscillations. Even though the TBO is the result of strong air–sea interaction, the circulation cells during TBO years are, as yet, not well understood. In the present study, an attempt has been made to understand the interannual variability of the mean meridional circulation and local monsoon circulation over south Asia in connection with the TBO. The stream function computed from the zonal mean meridional wind component of NCEP=NCAR reanalysis data for the years 1950–2003 is used to represent the meanmeridional circulation. Mean meridional mass transport in the topics reverses from a weak monsoon to a strong monsoon in the presence of ENSO, but in normal TBO yearsmean transport remains weak across the Northern Hemisphere. The meridional temperature gradient, which drives the mean meridional circulation, also shows no reversal during the normal TBO cycle. The local Hadley circulation over the monsoon area follows the TBO cycle with anomalous ascent (descent) in strong (weak) monsoon years. During normal TBO years, the Equatorial region and Indian monsoon areas exhibit opposite local Hadley circulation anomalies
Continuation and discontinuation of local institution in community based natural resource management
Resumo:
Currently the push toward frontier areas, which until twenty years ago were still largely untouched by commercial agriculture, is taking place on a massive scale. This push is being driven not the least by global economic developments, such as the price increase of agriculture commodities like coffee and cocoa. In most cases the indigenous communities become trapped between the state monopoly in natural resource management and the competition for resources by external actors. In this processes the indigenous communities start to lose their access to resources. Another victim in this process is the environment where the natural resources are imbedded. International and national organizations working to conserve environment have became conscious of the important role that indigenous people could fulfill as partners in this endeavour. This partnership in struggle has produced a new discourse on the relationship between indigenous people and their environment. As a further consequence, programs were set up to develop what became known as Community Based Natural Resource Management (CBNRM) with its numerous variations. Based on a case study in a village on the eastern border of the Lore Lindu National Park in Central Sulawesi, this study questioned the basic assumption behind the concept of Community Based Natural Resource Management (CBNRM). Namely the assumption that communities living at the margin of forest are socially and culturally homogenous, still more or less egalitarian, and basically living in harmony with their natural environment. This study was inspired by the persistent critique – although still a minority – on the basic assumption the CBNRM from academicians and practitioners working through the Entitlement perspective. Another inspiration was the mounting critique toward the participatory approach. In its effort the study explore further the usefulness of certain approaches. One of the approach much relied on in this study was the local history of the community studied, through exerting oral and local written documents on local history, legends and local stories. These sources proofed quite capable in bringing the local history into the light. Another was the actor oriented approach, which later came to be supported by the concept of Social Pool Resources. The latter concept proofed to be useful as analytical instrument to integrate social institutions and the common pool resources, as a field of action for the different actors as human agencies.
Resumo:
Distributed systems are one of the most vital components of the economy. The most prominent example is probably the internet, a constituent element of our knowledge society. During the recent years, the number of novel network types has steadily increased. Amongst others, sensor networks, distributed systems composed of tiny computational devices with scarce resources, have emerged. The further development and heterogeneous connection of such systems imposes new requirements on the software development process. Mobile and wireless networks, for instance, have to organize themselves autonomously and must be able to react to changes in the environment and to failing nodes alike. Researching new approaches for the design of distributed algorithms may lead to methods with which these requirements can be met efficiently. In this thesis, one such method is developed, tested, and discussed in respect of its practical utility. Our new design approach for distributed algorithms is based on Genetic Programming, a member of the family of evolutionary algorithms. Evolutionary algorithms are metaheuristic optimization methods which copy principles from natural evolution. They use a population of solution candidates which they try to refine step by step in order to attain optimal values for predefined objective functions. The synthesis of an algorithm with our approach starts with an analysis step in which the wanted global behavior of the distributed system is specified. From this specification, objective functions are derived which steer a Genetic Programming process where the solution candidates are distributed programs. The objective functions rate how close these programs approximate the goal behavior in multiple randomized network simulations. The evolutionary process step by step selects the most promising solution candidates and modifies and combines them with mutation and crossover operators. This way, a description of the global behavior of a distributed system is translated automatically to programs which, if executed locally on the nodes of the system, exhibit this behavior. In our work, we test six different ways for representing distributed programs, comprising adaptations and extensions of well-known Genetic Programming methods (SGP, eSGP, and LGP), one bio-inspired approach (Fraglets), and two new program representations called Rule-based Genetic Programming (RBGP, eRBGP) designed by us. We breed programs in these representations for three well-known example problems in distributed systems: election algorithms, the distributed mutual exclusion at a critical section, and the distributed computation of the greatest common divisor of a set of numbers. Synthesizing distributed programs the evolutionary way does not necessarily lead to the envisaged results. In a detailed analysis, we discuss the problematic features which make this form of Genetic Programming particularly hard. The two Rule-based Genetic Programming approaches have been developed especially in order to mitigate these difficulties. In our experiments, at least one of them (eRBGP) turned out to be a very efficient approach and in most cases, was superior to the other representations.
Resumo:
In this thesis I present a language for instructing a sheet of identically-programmed, flexible, autonomous agents (``cells'') to assemble themselves into a predetermined global shape, using local interactions. The global shape is described as a folding construction on a continuous sheet, using a set of axioms from paper-folding (origami). I provide a means of automatically deriving the cell program, executed by all cells, from the global shape description. With this language, a wide variety of global shapes and patterns can be synthesized, using only local interactions between identically-programmed cells. Examples include flat layered shapes, all plane Euclidean constructions, and a variety of tessellation patterns. In contrast to approaches based on cellular automata or evolution, the cell program is directly derived from the global shape description and is composed from a small number of biologically-inspired primitives: gradients, neighborhood query, polarity inversion, cell-to-cell contact and flexible folding. The cell programs are robust, without relying on regular cell placement, global coordinates, or synchronous operation and can tolerate a small amount of random cell death. I show that an average cell neighborhood of 15 is sufficient to reliably self-assemble complex shapes and geometric patterns on randomly distributed cells. The language provides many insights into the relationship between local and global descriptions of behavior, such as the advantage of constructive languages, mechanisms for achieving global robustness, and mechanisms for achieving scale-independent shapes from a single cell program. The language suggests a mechanism by which many related shapes can be created by the same cell program, in the manner of D'Arcy Thompson's famous coordinate transformations. The thesis illuminates how complex morphology and pattern can emerge from local interactions, and how one can engineer robust self-assembly.
Resumo:
Local descriptors are increasingly used for the task of object recognition because of their perceived robustness with respect to occlusions and to global geometrical deformations. We propose a performance criterion for a local descriptor based on the tradeoff between selectivity and invariance. In this paper, we evaluate several local descriptors with respect to selectivity and invariance. The descriptors that we evaluated are Gaussian derivatives up to the third order, gray image patches, and Laplacian-based descriptors with either three scales or one scale filters. We compare selectivity and invariance to several affine changes such as rotation, scale, brightness, and viewpoint. Comparisons have been made keeping the dimensionality of the descriptors roughly constant. The overall results indicate a good performance by the descriptor based on a set of oriented Gaussian filters. It is interesting that oriented receptive fields similar to the Gaussian derivatives as well as receptive fields similar to the Laplacian are found in primate visual cortex.