Dry Friction in the Frenkel-Kontorova-Tomlinson Model: Dynamical Properties

Wearless friction is investigated in a simple mechanical model called Frenkel-Kontorova-Tomlinson model. We have introduced this model in [Phys. Rev. B, Vol. 53, 7539 (1996)] where the static friction has already been considered. Here the model is treated for constant sliding speed. The kinetic friction is calculated numerically as well as analytically. As a function of the sliding velocity it shows many structures which can be understood by varies kinds of phonon resonances (normal, superharmonic and parametric) caused by the so-called "washboard wave". For increasing interaction strength the regular motion becomes chaotic (fluid-sliding state). The fluid sliding state is mainly determined by the density of decay channels of m washboard waves into n phonons. We also find strong bistabilities and coherent motions with superimposed dark envelope solitons which interact nondestructively.Comment: Written in RevTeX, figures in PostScript, appears in Z. Phys.

Cooperative Purchasing Micro-Evolutions: A Longitudinal International Study

This paper deals with the evolution of relatively young purchasing groups. Although previous research focussed on macro-evolutionary phases of purchasing groups, no attention has yet been paid to the intra-phase developments, the so-called ‘micro-evolutions’. Insight into micro-evolutions is crucial to better understand how purchasing groups (can) develop over time. We conducted three in-depth case studies in different countries and identified five dimensions of micro-evolutions: member relationships, objectives, activities, organisation, and resources. For each dimension, we provide an overview of micro-evolutions to guide purchasing groups in developing the dimension. We conclude that the dimension ‘activities’ is very important and that purchasing groups do not have to develop the dimensions simultaneously

Issues and Challenges in Validating Military Simulation Models

The purpose of this thesis is to address the challenges of validating simulation models, especially those challenges facing military simulation analysts. Three distinct issues are of concern to the military simulation analyst: (1) What type of validation effort do the academic experts recommend? (2) What does the military policy say is necessary for a proper validation effort? (3) What can a simulation practitioner realistically accomplish given time and resource constraints? Four methodologies were chosen to represent the academic perspective on validation. A model of validation methods is integrated from the methodologies of these four simulation validation references. The validation policies of the Army, Navy, and Air Force are examined and analyzed for their methodologies to be applied to simulations. The integrated model is compared to these policies that are being formed within the DoD to determine the relationship between the academic experts and the military policies. Case studies of validation efforts are examined and analyzed for the methodologies used by simulation practitioners. The integrated model is compared to the case studies to examine the relationship between the academic experts and the actual practitioners. Finally, conclusions and observations are drawn from all of these comparisons

Implementing the Next Economy in a Unified Context: A Case Study of the Paddle Prairie Mall Corporation

A recent paper entitled "Native and Local Economics: A Consideration of Economic Evolution and the Next Economy" (Robinson and Ghostkeeper, 1987:138-144) by the authors proposed a model for community-based native business development based upon the fusing of community culture with corporate culture in the information and service economy. This model has now been implemented by a Metis entrepreneur in the northern Alberta settlement of Paddle Prairie and is evaluated using the "unified approach" to economic development described by Higgins and Higgins (1979). In this way the new venture's performance is assessed against the following criteria: employment generation, income creation, contribution to regional ecological harmony and maximization of cultural enrichment. It is concluded that the Paddle Prairie Mall Corporation is a practical demonstration of the unified approach in Canada's mid-North and that the "Metis way of doing things," born of the bush economy, is an indigenous Canadian variant of the unified approach that acknowledges the importance of sociocultural and ecological factors in development planning. It remains to be seen whether or not the Metis way of doing things has an Inuit or Indian analogue and to what degree the next economy model can be equally well applied in non-Metis native communities.Key words: community-based economic development, unified development, bush and next (information and service) economies, Metis, case studyMots clés: développement économique au sein la communauté, développement unifié, économie naturelle et prochaine économie (information et services), métis, étude de ca

Native and Local Economics: A Consideration of Economic Evolution and the Next Economy

A growing body of social-scientific literature drawing on the experience of village-based northern bush economies demonstrates that adaptation to industrial economy entrepreneurial opportunities is both difficult and problematic. An analysis of the basic social and administrative structures of the bush, industrial and "next" economies (those focused on information and service) reveals that the bush economy has many shared structural parallels with the next economy and that this congruence can be exploited by members of the bush economy seeking next economy business opportunities. In particular it is noted that the bush economy household unit of production has strong affinities to the re-emergence of small businesses based on a family model, generalist skills, cooperative management, utilization of appropriate new technology, disintermediation and emphasis on the integration of work with the entrepreneur's cultural and personal values. A model is proposed for community-based share offerings and is developed to include community corporate culture, local employee training and the creation of new business opportunities. This model emphasizes the retention of locally generated capital in the community and its utilization for the start-up of a variety of businesses in the information and service sector.Key words: village and bush economies, next (information and service) economy, native economic development, community-based development, entrepreneurship Un nombre croissant de documents sociaux-scientifiques qui s'appuient sur l'expérience des économies naturelles du Nord à partir de villages, montre que l'adaptation aux opportunités qui découlent de l'esprit d'entreprise dans une économie industrielle, est à la fois difficile et problématique. Une analyse des structures sociales et administratives fondamentales de l'économie naturelle, de l'économie industrielle et de la «prochaine» économie (celle qui se concentre sur l'information et les services) révèle que cette dernière et l'économie naturelle ont des structures parallèles sur bien des points. L'analyse révèle aussi que cette congruence peut être mise à profit par les membres de l'économie naturelle qui cherchent des opportunités d'affaires dans la prochaine économie. En particulier, on remarque que l'unité familiale de production de l'économie naturelle a de fortes affinités avec la réapparition de petites entreprises fondées sur le modèle familial, le savoir-faire polyvalent, la gestion coopérative, l'utilisation de nouvelles technologies appropriées, la suppression des intermédiaires et l'accent mis sur l'intégration du travail aux valeurs culturelles et personnelles de l'homme d'affaires. On propose un modèle pour des offres d'actions dans la communauté, qui est développé pour inclure la culture corporative de la communauté, la formation des employés sur place et la création de nouvelles opportunités dans les affaires. Ce modèle met l'accent sur la rétention dans la communauté du capital créé sur place, et son utilisation pour faire démarrer une variété d'entreprises dans le secteur de l'information et des services. Mots clés : économies de village et économie naturelle, prochaine économie (information et services), développement économique indigène, développement fondé sur la communauté, esprit d'entrepris

State of Health in Northern Kentucky: How We Compare, Why it Matters to Business

County-level data is becoming increasingly important for rural health planning. This presentation analyzes the health of several northern Kentucky counties and the potential consequences for the region’s employers

Periodic control and the optimality of aircraft cruise

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76156/1/AIAA-44557-889.pd