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排序方式: 共有825条查询结果,搜索用时 15 毫秒
131.
Jose María Alvarez-Rodríguez Jose Emilio Labra-Gayo Patricia Ordoñez de Pablos 《Computers in Industry》2014
The present paper introduces and reviews existing technology and research works in the field of e-Procurement. More specifically this survey aims to collect those relevant approaches that have tackled the challenge of delivering more advanced and intelligent e-Procurement management systems due to its relevance in the industry to afford more timely, adaptable and flexible decisions in purchasing processes. Although existing tools and techniques have demonstrated their ability to manage e-Procurement processes as a part of a supply management system there is a lack of interoperability among tools, tangled dependencies between processes or difficulties to exploit existing data and information to name a few that are preventing a proper use of the new dynamic and data-based environment. On the other hand semantic-based technologies emerge to provide the adequate building blocks to represent domain-knowledge and elevate the meaning of information resources through a common and shared data model (RDF) with a formal query language (SPARQL) and accessible via the Internet Protocols. In this sense the Linked Data effort has gained momentum to apply the principles of the aforementioned initiative to boost the re-use of information and data across different tools and processes. That is why authors review both existing open issues in the context e-Procurement with special focus on public procurement and semantic-based approaches to address them. To do so a preliminary research study is conducted to assess the state of the art in the context of e-Procurement and semantic-based systems. Afterwards main drawbacks of existing e-Procurement systems are presented to narrow down in semantic-based approaches applied to this field. Once the current status in both areas is reviewed, authors purpose the use and creation of an e-Procurement index to evaluate the quality of service of procurement systems. In this light the Analytical Hierarchy Process (AHP) method is used to set up an initial weight for each indicator in the index and to perform a first comparison between traditional and semantic-based approaches. Finally some discussion, conclusions and future challenges are also outlined. 相似文献
132.
We present a new methodology of user simulation applied to the evaluation and refinement of stochastic dialog systems. Common weaknesses of these systems are the scarceness of the training corpus and the cost of an evaluation made by real users. We have considered the user simulation technique as an alternative way of testing and improving our dialog system. We have developed a new dialog manager that plays the role of the user. This user dialog manager incorporates several knowledge sources, combining statistical and heuristic information in order to define its dialog strategy. Once the user simulator is integrated into the dialog system, it is possible to enhance the dialog models by an automatic strategy learning. We have performed an extensive evaluation, achieving a slight but clear improvement of the dialog system. 相似文献
133.
We used a digital feedback control loop system to produce reproducible fixed volume transmission holograms of high diffraction efficiency. Different strategies were investigated to obtain holograms of good quality and the highest refractive index modulation depth. Using this control system, we were able to record holograms with stationary fringes. Additionally to using the stationary fringe recording, a double recording-fixing schedule resulted in being the most appropriate one to produce reproducible holograms of better characteristics. This strategy is discussed and compared with other already established ones. 相似文献
134.
135.
The Mediterranean Diet decreases LDL atherogenicity in high cardiovascular risk individuals: a randomized controlled trial 下载免费PDF全文
Álvaro Hernáez Olga Castañer Alberto Goday Emilio Ros Xavier Pintó Ramón Estruch Jordi Salas‐Salvadó Dolores Corella Fernando Arós Lluis Serra‐Majem Miguel Ángel Martínez‐González Miquel Fiol José Lapetra Rafael de la Torre M. Carmen López‐Sabater Montserrat Fitó 《Molecular nutrition & food research》2017,61(9)
136.
Jean-Yves Colle Emilio A. Maugeri Catherine Thiriet Zeynep Talip Franco Capone Jean-Pol Hiernaut 《Journal of Nuclear Science and Technology》2013,50(5):700-711
A new system has been developed to determine absolute quantities of gas (mainly noble gases) released during thermal desorption in the range from 10?12 to 10?5 mol with a precision of few percent. The system is actually designed for simultaneous measurement of gaseous elements like He, Xe, Kr, thermally released from nuclear fuel samples and also allows the determination of the release kinetics as a function of time. This system, called Quantitative GAs MEasurement System (Q-GAMES), is based on the principle of collecting, purifying and spiking the sample gas in a “high-pressure” chamber, and continuous sampling of the gas for mass spectrometric analysis without sample depletion during the experiment. It is equipped with its own spike generator and with different gas purification systems. It is shown that this system fulfills the requirement to work with two existing very high-temperature gas desorption facilities for nuclear materials. This paper describes the Q-GAMES principle, the spiking system, its calibration, its operative mode, the different quantification techniques, as well as its technical data, in combination with some examples of typical application. 相似文献
137.
Radiation synthesis of a thermo-pH responsive binary graft copolymer (PP-g-DMAEMA)-g-NIPAAm by a two step
method 总被引:1,自引:1,他引:0
Summary (PP-g-DMAEMA)-g-NIPAAm was synthesized using gamma radiation from a 60Co
source. Graft polymerization of N,N’-dimethylaminoethylmethacrylate (DMAEMA) onto polypropylene (PP)
was accomplished in about 100 percent yield by the mutual irradiation technique at a dose of 10 kGy.
Grafting of N-isopropylacrylamide (NIPAAm) onto PP-g-DMAEMA was carried out by the pre-irradiation method
with doses from 20 to 100 kGy. The influence of temperature, reaction time, and monomer concentration
on grafting yield was studied. Grafting processes were confirmed by infrared spectroscopy (FTIR-ATR).
(PP-g-DMAEMA)-g-NIPAAm films were characterized by thermogravimetric analysis (TGA) and differential
scanning calorimetry (DSC). The lower critical solution temperature (LCST) and critical pH point of
the films were obtained by water contact angle and percent swelling measurements. The LCST was also
determined by DSC. We report here hare a new binary graft copolymer which shows two LCST values, synthesized
in two steps. 相似文献
138.
G Stoica I Castelló Serrano A Figuerola I Ugarte R Pacios E Palomares 《Nanoscale》2012,4(17):5409-5419
Quantum dot-hydrotalcite layered nanoplatforms were successfully prepared following a one-pot synthesis. The process is very fast and a priori delamination of hydrotalcite is not a prerequisite for the intercalation of quantum dots. The novel materials were extensively characterized by X-ray diffraction, thermogravimetry, infrared spectroscopy, transmission electron microscopy, true color fluorescence microscopy, photoluminescence, and nitrogen adsorption. The quantum dot-hydrotalcite nanomaterials display extremely high stability in mimicking physiological media such as saline serum (pH 5.5) and PBS (pH 7.2). Yet, quantum dot release from the solid structure is noted. In order to prevent the leaking of quantum dots we have developed a novel strategy which consists of using tailor made double layered hydrotalcites as protecting shells for quantum dots embedded into silica nanospheres without changing either the materials or the optical properties. 相似文献
139.
L. Emilio Morales Garry Griffith Victor Wright Euan Fleming Wendy Umberger Nam Hoang 《Meat science》2013
Australian beef consumers have different preferences given their characteristics and the effect on expected quality of cues related to health, production process and eating experience. Beef brands using Meat Standards Australia (MSA) grades can help to signal quality and reduce consumers' uncertainty when shopping. The objective of this study is to identify the characteristics of beef buyers and their perceptions about product attributes that affect the propensity to buy branded beef. Binary logistic models were applied identifying differences between all respondents and the potential target market, including buyers in medium to high income segments, and between buyers in the target market who would buy branded beef for taste and health reasons. Variables increasing the propensity to buy branded beef include previous experience, appreciation for branded cuts and concern about quality more than size. Finally, variations in preferences for marbling and cut were found between buyers who would buy branded beef for taste and health reasons. 相似文献
140.
Emilio Fernndez‐Mateos Beatriz Maci Miguel Yus 《Advanced Synthesis \u0026amp; Catalysis》2013,355(7):1249-1254
Herein, we report an efficient catalytic system for the enantioselective addition of alkyl Grignard reagents to a broad range of aliphatic aldehydes with good yields and enantioselectivities. Remarkably, the challenging methylmagnesium bromide (MeMgBr) can also be added to a variety of aliphatic aldehydes, providing versatile chiral methyl carbinol units with unprecedented yields and enantioselectivities in a simple one‐pot procedure under mild conditions. 相似文献