UbiqStack: a taxonomy for a ubiquitous computing software stack

This paper describes a taxonomy for a ubiquitous computing software stack called UbiqStack. Through the lens of the UbiqStack taxonomy we survey a variety of subsystems designed to be the building blocks from which sophisticated infrastructures for ubiquitous computing are assembled. Our experience shows that many of these building blocks fit neatly into one of the five UbiqStack categories, each containing functionally-equivalent components. Effectively identifying the best-fit “Lego pieces”, which in turn determines the composite functionality of the resulting infrastructure, is critical. The selection process, however, is impeded by the lack of convention for labeling these classes of building blocks. The lack of clarity with respect to what ready-made subsystems are available within each class often results in naive re-implementation of ready-made components, monolithic and clumsy implementations, and implementations that impose non-standard interfaces onto the applications above. This paper describes the UbiqStack classes of subsystems and explores each in light of the experience gained over 2 years of active development of both ubiquitous computing applications and software infrastructures for their deployment.     

Exploring Problems with Function Analysis. Experimental Insights for Team Management

Problem analysis is an important, but mainly neglected part of the problem‐solving process. The theory of inventive problem solving (TRIZ) offers an instrument called function analysis to conduct problem analysis, which is especially useful for exploring a problem. This process is based on an idea applied in different creativity techniques, saying that behind one problem statement many problem formulations may occur, which allows for evaluation and selection of those problem formulations before looking for problem solutions. The application of function analysis as a tool for teams is recommended for a number of reasons. In so doing so, two main questions arise: (i) Should function analysis be used with the help of an external moderator? and: (ii) Should it be applied with currently available special software? After introducing the basics of function analysis this article provides key findings deducted from an experiment addressing these questions. An important result is the remarkable learning effect, which occurs while using function analysis in teams. By applying function analysis in R&D, companies will be able to get deeper and team‐based problem explorations, which may lead to maturing problem solutions.     

Adaptive Zugriffskontrollverfahren

IT service providers are increasingly hosting different services of different customers on a shared IT infrastructure. While this fosters utilization of hardware infrastructure, system malfunctions, unexpected service behaviour or peak demands for one or more services may exploit resource pools (CPU, I/O, main memory, bandwidth etc.), entailing rejection of service requests. In this paper we describe models for dynamic admission control on shared infrastructures. The admission control model decides whether to accept, buffer or reject a service request based on the revenue, Service Level Agreements (SLAs) and its resource demand in comparison to the actual workload to maximize overall revenue. Simulations of a media streaming infrastructure have been used for evaluation and comparison with traditional admission control policies.     

Strain-dependent recovery of spontaneous hindlimb movement in spinal cord transected mice (CD1, C57BL/6, BALB/c).

Reorganization and plasticity after spinal cord injury have been recently shown to take place in sublesional neuronal networks, but the possibility of strain-dependent changes at that level has never been explored. The authors studied the spontaneous return of hindlimb movement in low-thoracic spinal cord transected (Tx) mice from 3 commonly used strains. Without intervention, most CD1, C57BL/6, and BALB/c mice displayed some hindlimb movement recovery after Tx. Although all assessment methods unanimously reported that CD1 displayed higher recovery levels than did the C57BL/6 and BALB/c, higher scores were generally found with the Antri-Orsal-Barthe (M. Antri, D. Orsal, & J. Y. Barthe, 2002) and the Average Combined Score (P. A. Guertin, 2005a) methods. Such spontaneous recovery in low-thoracic Tx mice is likely the result of neuronal plasticity at the lumbosacral spinal cord level, suggesting that these sublesional changes are strain dependent. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of temperature and oxygen content on the flowing liquid metal corrosion of structural steels in the Pb–Bi eutectic

We performed corrosion tests of 1000 h each on approximately 20 types of structural steels (austenitic, ferritic and martensitic) in convection loops with flowing Pb–Bi at 500, 450 and 400 °C and a temperature gradient of 100 °C. These experiments were performed in liquid Pb–Bi with different oxygen concentrations (from approximately 1 × 10⁻⁶ to 2 × 10⁻⁵ wt.%) to ascertain at what oxygen concentration and up to what temperature the oxygen technology can create protective oxide or spinel layers to reduce or prevent corrosion. The results showed that the structural materials contemplated for building an ADS system, including 9% Cr–1% Mo (W) martensitic steels and similar steels with a higher Si content (2–3%), can be used with their surface unpassivated at up to 450 °C and suffer only minimal corrosion (up to 5 μm/year). At higher temperatures, their surface must be passivated prior to and regularly during the operation; however, no technology to perform such passivation in the presence of Pb–Bi is known that this time. In addition, we measured the impact of various alloying elements, such as Fe, Cr, Ni, Mn, Si, Al and Mo, on the corrosion of such steels and searched for potential ways to passivate their surface or create protective oxide or spinel layers during operation by varying the amount of oxygen in liquid Pb–Bi.     

共话工业以太网风云变幻--访西门子自动化与驱动集团工业通信全球地区总经理贺日安及

2004年10月19日至20日,中国工业以太网发展论坛暨全国第一届工业以太网技术发展与应用研讨会(IEHF2004)在京召开.借此机会,本刊记者采访了西门子自动化与驱动集团工业通信全球地区总经理贺日安和德国菲尼克斯电气集团自动化总裁Martin Muller,畅谈工业以太网的过去、现在与未来.     

Simulation as a tool for optimizing memory accesses on NUMA machines

Due to the inherent non-uniformity in the memory system, programmers and users of non-uniform memory access (NUMA) machines have to take special care of the memory performance of their applications. This paper discusses a variety of potential improvements with respect to cache misses, cache invalidations, and inter-node communication. This study is based on the simulation tool SIMT, which models the memory hierarchy in detail and is capable of providing complete, accurate information about all dynamic memory references. This information can be used to analyze the memory access behavior of applications and thereby forms the basis for any optimization with respect to memory accesses.     

Satellite-derived parameters for biological modelling in coastal waters: Illustration over the eastern continental shelf of the Bay of Biscay

In biological modelling of the coastal phytoplankton dynamics, the light attenuation coefficient is often expressed as a function of the concentrations of chlorophyll and mineral suspended particulate matter (SPM). In order to estimate the relationship between these parameters over the continental shelf of the northern Bay of Biscay, a set of in situ data has been gathered for the period 1998-2003 when SeaWiFS imagery is available. These data comprise surface measurements of the concentrations of total SPM, chlorophyll, and irradiance profiles from which is derived the attenuation coefficient of the photosynthetically available radiation, K_PAR. The performance of the IFREMER look-up table used to retrieve the chlorophyll concentration from the SeaWiFS radiance is evaluated on this new set of data. The quality of the estimated chlorophyll concentration is assessed from a comparison of the variograms of the in situ and satellite-derived chlorophyll concentrations. Once the chlorophyll concentration is determined, the non living SPM, which is defined as the SPM not related to the dead or alive endogenous phytoplankton, is estimated from the radiance at 555 nm by inverting a semi-analytic model. This method provides realistic estimations of concentrations of chlorophyll and SPM over the continental shelf all over the year. Finally, a relationship, based on non living SPM and chlorophyll, is proposed to estimate K_PAR on the continental shelf of the Bay of Biscay. The same formula is applied to non living SPM and chlorophyll concentrations, observed in situ or derived from SeaWiFS radiance.     

Substrate age and precipitation effects on Hawaiian forest canopies from spaceborne imaging spectroscopy

We used spaceborne imaging spectroscopy provided by the Earth Observing-1 Hyperion sensor to quantify the relative importance of precipitation and substrate age that control ecosystem development and functioning in Metrosideros polymorpha rainforests of Hawaii. Four hyperspectral vegetation indices provided metrics of forest canopy structure, biochemistry and physiology to compare along gradients of annual rainfall (750 to > 6000 mm year^− 1) and substrate age (0 to 250,000 years). The canopy greenness index NDVI increased with annual precipitation and substrate age, but saturated in forests with rainfall of 3000 mm year^− 1. Precipitation and substrate age were roughly equal contributors to the observed greenness of the forests. A canopy water content index (NDWI) also increased with precipitation and substrate age, but did not reach a maximum until very wet (> 5000 mm year^− 1) forest conditions were encountered on the oldest substrates. The water index appears superior to the NDVI in capturing spatial and climate-substrate driven variations in canopy structure. The photochemical reflectance index (PRI) indicated highest light-use efficiency levels in canopies on the most developed substrates and at annual precipitation levels of 3-4500 mm year^− 1. A leaf carotenoid index (CRI) suggested a maximum canopy photosynthetic capacity at ∼ 4000 mm rainfall year^− 1 on the oldest substrates. These results quantify the sensitivity of rainforest canopies to changing precipitation and soil conditions, and they corroborate plot-scale analyses in native Hawaiian forests ecosystems. Structural and functional studies of remote rainforest regions are possible with spaceborne imaging spectroscopy, and could be used to understand the dynamics of rainforests with climate change.