Students’ expectations from graduate studies in heritage (tourism) management

This article provides certain key aspects that might help to further develop academic heritage education. These have been discussed within brainstorming and round-table sessions carried out by World Heritage students at BTU Cottbus-Senftenberg. Important aspects regarding expectations, current issues and prospective career opportunities were selected after these sessions. With the idea of our International Master Programme in mind, the results of this work have been summarized to identify what makes a good focus to Heritage Studies and further strategies to improve this discipline. It was concluded that international and interdisciplinary approaches should serve as the basis to facilitate personal research interests, critical thinking, a sense of student community and how all these can be applied to a future professional career. External students, faculty members and heritage professionals are invited to join this debate

A Two-step Statistical Approach for Inferring Network Traffic Demands (Revises Technical Report BUCS-2003-003)

Accurate knowledge of traffic demands in a communication network enables or enhances a variety of traffic engineering and network management tasks of paramount importance for operational networks. Directly measuring a complete set of these demands is prohibitively expensive because of the huge amounts of data that must be collected and the performance impact that such measurements would impose on the regular behavior of the network. As a consequence, we must rely on statistical techniques to produce estimates of actual traffic demands from partial information. The performance of such techniques is however limited due to their reliance on limited information and the high amount of computations they incur, which limits their convergence behavior. In this paper we study a two-step approach for inferring network traffic demands. First we elaborate and evaluate a modeling approach for generating good starting points to be fed to iterative statistical inference techniques. We call these starting points informed priors since they are obtained using actual network information such as packet traces and SNMP link counts. Second we provide a very fast variant of the EM algorithm which extends its computation range, increasing its accuracy and decreasing its dependence on the quality of the starting point. Finally, we evaluate and compare alternative mechanisms for generating starting points and the convergence characteristics of our EM algorithm against a recently proposed Weighted Least Squares approach.National Science Foundation (ANI-0095988, EIA-0202067, ITR ANI-0205294

An Energy-conscious Transport Protocol for Multi-hop Wireless Networks

We present a transport protocol whose goal is to reduce power consumption without compromising delivery requirements of applications. To meet its goal of energy efficiency, our transport protocol (1) contains mechanisms to balance end-to-end vs. local retransmissions; (2) minimizes acknowledgment traffic using receiver regulated rate-based flow control combined with selected acknowledgements and in-network caching of packets; and (3) aggressively seeks to avoid any congestion-based packet loss. Within a recently developed ultra low-power multi-hop wireless network system, extensive simulations and experimental results demonstrate that our transport protocol meets its goal of preserving the energy efficiency of the underlying network.Defense Advanced Research Projects Agency (NBCHC050053

Utilização de um delineamento composto central rotacional para avaliação microbiológica de polpas de açaí pasteurizadas.

O açaí é um fruto nativo da região Amazônica brasileira, cuja polpa tem sido amplamente comercializada no mundo. Sendo altamente perecível pelas suas características intrínsecas e de pré-processamento, o processo de pasteurização torna-se essencial. Dessa forma, o objetivo deste trabalho foi investigar como o binômio tempo e temperatura influencia nas características microbiológicas da polpa, e, através de um delineamento experimental determinar as melhores condições de processo visando à segurança do produto. Utilizou-se polpa de açaí proveniente de Belém, Pará e um sistema de pasteurização tubular. O planejamento adotado foi do tipo composto central rotacional 22 e como respostas foram realizadas análises de bactérias mesófilas e bolores e leveduras. A avaliação estatística do planejamento mostrou que, para bactérias, as variáveis temperatura e tempo, linear e quadrática, foram significativas (p?0,05). Porém, quando submetidos à análise de variância, os resultados foram considerados insatisfatórios para geração de um modelo preditivo (R2 = 0,39; Fcalculado/Ftabelado0,10). Entretanto, os gráficos de tendência indicaram que a variável tempo exerceu maior influência no processo. Para bolores e leveduras, observou-se destruição em sua totalidade, com contagens finais de <10 UFC/g (est.). De acordo com o conjunto de resultados obtidos, sugere-se a adoção de um tempo mínimo de 35s e temperatura acima de 75ºC para a pasteurização da polpa de açaí

Gas-Phase Lubrication of ta-C by Glycerol and Hydrogen Peroxide. Experimental and Computer Modeling

Tetrahedrally coordinated hydrogen-free amorphous diamond-like carbon coating (denoted as ta-C) presents ultralow friction under boundary lubrication conditions at 80 °C in presence of OH-containing molecules. To understand the mechanism of ultralow friction, we performed gas-phase lubrication experiments followed by time-of-flight secondary ion mass spectrometry (ToF-SIMS) analyses and this using two simple molecules: deuterated glycerol and hydrogen peroxide. The experiments were complemented by computer simulations using the ReaxFF reactive force field. These simulations suggest a ta-C surface rich in sp^2 carbon with some reactive sp^1 carbon atoms, in agreement with previous energy filtered transmission electron microscopy (EFTEM) results. Sliding simulations show that the carbon surface atoms react with glycerol and hydrogen peroxide to form OH-termination. Moreover, the hydroxylation is then followed by the chemical dissociation of some of the glycerol molecules leading to the formation of water. This is in agreement with the secondary ion mass spectrometry (SIMS) analyses and mass spectrometer results obtained with gas-phase lubrication experiments with the same molecules. Both experimental and computer simulations strongly suggest that the hydroxylation of the carbon surface is at the origin of ultralow friction together with the formation of water-rich film in the sliding interface

Analytical evaluation of the output variability in production systems with general Markovian structure

Performance evaluation models are used by companies to design, adapt, manage and control their production systems. In the literature, most of the effort has been dedicated to the development of efficient methodologies to estimate the first moment performance measures of production systems, such as the expected production rate, the buffer levels and the mean completion time. However, there is industrial evidence that the variability of the production output may drastically impact on the capability of managing the system operations, causing the observed system performance to be highly different from what expected. This paper presents a general methodology to analyze the variability of the output of unreliable single machines and small-scale multi-stage production systems modeled as General Markovian structure. The generality of the approach allows modeling and studying performance measures such as the variance of the cumulated output and the variance of the inter-departure time under many system configurations within a unique framework. The proposed method is based on the characterization of the autocorrelation structure of the system output. The impact of different system parameters on the output variability is investigated and characterized. Moreover, managerial actions that allow reducing the output variability are identified. The computational complexity of the method is studied on an extensive set of computer experiments. Finally, the limits of this approach while studying long multi-stage production lines are highlighted. © 2013 Springer-Verlag Berlin Heidelberg