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21.
To make media resources a prime citizen on the Web, we have to go beyond simply replicating digital media files. The Web is based on hyperlinks between Web resources, and that includes hyperlinking out of resources (e.g., from a word or an image within a Web page) as well as hyperlinking into resources (e.g., fragment URIs into Web pages). To turn video and audio into hypervideo and hyperaudio, we need to enable hyperlinking into and out of them. The W3C Media Fragments Working Group is taking on the challenge to further embrace W3C??s mission to lead the World Wide Web to its full potential by developing a Media Fragment protocol and guidelines that ensure the long-term growth of the Web. The major contribution of this paper is the introduction of Media Fragments as a media-format independent, standard means of addressing media resources using URIs. Moreover, we explain how the HTTP protocol can be used and extended to serve Media Fragments and what the impact is for current Web-enabled media formats.  相似文献   
22.
We have in previous studies reported our findings and concern about the reliability and validity of the evaluation procedures used in comparative studies on competing effort prediction models. In particular, we have raised concerns about the use of accuracy statistics to rank and select models. Our concern is strengthened by the observed lack of consistent findings. This study offers more insights into the causes of conclusion instability by elaborating on the findings of our previous work concerning the reliability and validity of the evaluation procedures. We show that model selection based on the accuracy statistics MMRE, MMER, MBRE, and MIBRE contribute to conclusion instability as well as selection of inferior models. We argue and show that the evaluation procedure must include an evaluation of whether the functional form of the prediction model makes sense to better prevent selection of inferior models.  相似文献   
23.
Extracts of different body parts of adult Trichoptera were tested for electrophysiological activity. Extracts of the IVth and Vth abdominal sternites of femaleHydropsyche angustipennis, Rhyacophila nubila, andR. fasciata, containing a paired exocrine gland, elicited significant electroan-tennographic responses when tested on conspecific male antennae. The paired gland occurs also in males of all the species, and inH. angustipennis, extracts from males were more active than female extracts when tested on male antennae. Female and male extracts from all species were analyzed by gas chromatography with simultaneous flame ionization and electroantennographic detection (EAD). EAD-active peaks in female extracts, stimulating male antennae, were identified inH. angustipennis as nonan-2-one; and inR. nubila andR. fasciata as heptan-2-one, heptan-2-ol, nonan-2-one, and nonan-2-ol. EAD-active components from maleH. angustipennis stimulating male antennae were octan-2-one, nonan-2-one (major peak), (Z)-6-nonen-2-one, decan-2-one, and a methylbranched decan-2-one. Female extracts and synthetic mixtures of compounds identified from femaleH. angustipennis andR. fasciata were tested for attractivity in the field. High catches with control traps obscured the results, but a synthetic mixture of the four identified compounds was significantly attractive and not different from female extracts for attracting maleR. fasciata. InH. angustipennis, a synthetic six-component male blend, in which nonan-2-one was the major component, attracted significant numbers of male and femaleH. angustipennis. Extracts of maleR. nubila andR. fasciata contained acetophenone and hexanoic and octanoic acids but did not have any electrophysiological or behavioral activity on either male or female antennae of conspecifics. The occurrence of a female sex pheromone inRhyacophila and an aggregation pheromone inHydropsyche corresponds to earlier described differences in mating behaviors in the Rhyacophilidae and Hydropsychidae.  相似文献   
24.
Erik T. Thostenson 《Carbon》2006,44(14):3022-3029
The novel properties of carbon nanotubes have generated scientific and technical interest in the development of nanotube-reinforced polymer composites. In order to utilize nanotubes in multi-functional material systems it is crucial to develop processing techniques that are amenable to scale-up for high volume, high rate production. In this research we investigate a scalable calendering approach for achieving dispersion of CVD-grown multi-walled carbon nanotubes through intense shear mixing. Electron microscopy was utilized to study the micro and nanoscale structure evolution during the manufacturing process and optimize the processing conditions for producing highly-dispersed nanocomposites. After processing protocols were established, nanotube/epoxy composites were processed with varying reinforcement fractions and the fracture toughness and electrical/thermal transport properties were evaluated. The as-processed nanocomposites exhibited significantly enhanced fracture toughness at low nanotube concentrations. The high aspect ratios of the carbon nanotubes in the as-processed composites enabled the formation of a conductive percolating network at concentrations below 0.1% by weight. The thermal conductivity increased linearly with nanotube concentration to a maximum increase of 60% at 5 wt.% carbon nanotubes.  相似文献   
25.
Office workers perform tasks using different information and communication technologies (ICT) involving various postures. Adequate variation in postures and muscle activity is generally believed to protect against musculoskeletal complaints, but insufficient information exists regarding the effect on postural variation of using different ICT. Thus, this study among office workers aimed to determine and compare postures and postural variation associated with using distinct types of ICT. Upper arm, head and trunk postures of 24 office workers were measured with the Physiometer® over a whole day in their natural work and away-from-work environments. Postural variation was quantified using two indices: APDF(90-10) and EVA(sd). Various ICT had different postural means and variation. Paper-based tasks had more non-neutral, yet also more variable postures. Electronics-based tasks had more neutral postures, with less postural variability. Tasks simultaneously using paper- and electronics-based ICT had least neutral and least variable postures. Tasks without ICT usually had the most posture variability. Interspersing tasks involving different ICT could increase overall exposure variation among office workers and may thus contribute to musculoskeletal risk reduction.  相似文献   
26.
We present the first polynomial-time approximation schemes (PTASes) for the following subset-connectivity problems in edge-weighted graphs of bounded-genus: Steiner tree, low-connectivity survivable-network design, and subset TSP. The schemes run in $\mathcal{O}(n \log n)$ time for graphs embedded on both orientable and nonorientable surfaces. This work generalizes the PTAS framework from planar graphs to bounded-genus graphs: any problem that is shown to be approximable by the planar PTAS framework of Borradaile et al. (ACM Trans. Algorithms 5(3), 2009) will also be approximable in bounded-genus graphs by our extension.  相似文献   
27.
In this paper, we describe our progress in creating the framework for an interactive application that allows humans to actively participate in a t-SNE clustering process. t-SNE (t-Distributed Stochastic Neighbor Embedding) is a dimensionality reduction technique that maps high dimensional data sets to lower dimensions that can then be visualized for human interpretation. By prompting users to monitor outlying points during the t-SNE clustering process, we hypothesize that users may be able to make clustering faster and more accurate than purely algorithmic methods. Further research would test these hypotheses directly. We would also attempt to decrease the lag time between the various components of our application and develop an intuitive approach for humans to aid in clustering unlabeled data. Research into human assisted clustering can combine the strengths of both humans and computer programs to improve the results of data analysis.  相似文献   
28.

In this investigation, a comparative study for a NO X storage catalytic system was performed focusing on the parameters that affect the reduction by using different reductants (H2, CO, C3H6 and C3H8) and different temperatures (350, 250 and 150 °C), for a Pt/BaO/Al2O3 catalyst. Transient experiments show that H2 and CO are highly efficient reductants compared to C3H6 which is somewhat less efficient. H2 shows a significant reduction effect at relatively low temperature (150 °C) but with a low storage capacity. We find that C3H8 does not show any NO X reduction ability for NO X stored in Pt/BaO/Al2O3 at any of the temperatures. The formation of ammonia and nitrous oxide is also discussed.

  相似文献   
29.
Image calibration requires both linearization of pixel values and scaling so that values in the image correspond to real‐world luminances. In this paper we focus on the latter and rather than rely on camera characterization, we calibrate images by analysing their content and metadata, obviating the need for expensive measuring devices or modeling of lens and camera combinations. Our analysis correlates sky pixel values to luminances that would be expected based on geographical metadata. Combined with high dynamic range (HDR) imaging, which gives us linear pixel data, our algorithm allows us to find absolute luminance values for each pixel—effectively turning digital cameras into absolute light meters. To validate our algorithm we have collected and annotated a calibrated set of HDR images and compared our estimation with several other approaches, showing that our approach is able to more accurately recover absolute luminance. We discuss various applications and demonstrate the utility of our method in the context of calibrated color appearance reproduction and lighting design.  相似文献   
30.
Dynamically adaptive systems (DAS) must cope with system and environmental conditions that may not have been fully understood or anticipated during development. RELAX is a fuzzy logic-based specification language for identifying and assessing sources of environmental uncertainty, thereby making DAS requirements more tolerant of unanticipated conditions. This paper presents AutoRELAX, an approach that automatically generates RELAXed goal models to address environmental uncertainty. Specifically, AutoRELAX identifies goals to RELAX, which RELAX operators to apply, and the shape of the fuzzy logic function that establishes the goal satisfaction criteria. AutoRELAX generates different solutions by making tradeoffs between minimizing the number of RELAXed goals and maximizing delivered functionality by reducing the number of adaptations triggered by minor and adverse environmental conditions. In a recent extension, AutoRELAX uses a stepwise adaptation of weights to balance these two competing concerns and thereby further improve the utility of AutoRELAX. We apply it to two industry-based applications involving network management and a robotic controller, respectively.  相似文献   
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