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91.
Ram Mudambi 《Industry and innovation》2012,19(1):1-21
Research on the geographic clustering of economic activity dates back to the early twentieth century. It is recognized that in spite of advances in transportation and communications, clustering remains most critical, and is consequently prevalent, in knowledge-intensive fields. Multinational enterprises (MNEs) that increasingly base their value creation and competitive advantage on knowledge-intensive activities are key participants in clusters, affecting both the nature and intertemporal evolution of local innovative activities. However, the role of MNEs in clusters remains under-researched. This paper traces the origins of research on geographic clusters, identifies the seminal contributions focusing on the role of MNEs, discusses potential problems inherent to this area of inquiry and develops an organizing framework for new research. 相似文献
92.
The performance modeling study of Delay-Tolerant Network routing, in general, assumes the nodes to be homogeneous (in terms of features such as the coverage range) and uncompromised (in terms of forwarding messages). However, in realistic settings this may not be the case. The routing performance modeling of such realistic scenarios that involve multifariously-featured and egotistic nodes would be interesting and insightful. To this end, in this paper, we analytically model the routing behavior of such nodes using Ordinary Differential Equations for two different routing protocols namely, Epidemic Routing and Two-Hop Routing. Furthermore, we also study the degradation in the routing performance caused by an increase in the fraction of selfish nodes present in the heterogeneous node population. The proposed analytical model is validated via extensive simulations. 相似文献
93.
Gurung Thulo Ram Stewart Rodney A. Beal Cara D. Sharma Ashok K. 《Water Resources Management》2016,30(11):4037-4051
Water Resources Management - Diversified water supply schemes can reduce both peak demand and overall demand in the urban water supply network. Consequently, they provide benefits to both the water... 相似文献
94.
Francisco J. Fernandez-Luque David Pérez Félix Martínez Ginés Domènech Isabel Navarrete Juan Zapata Ramón Ruiz 《Ad hoc Networks》2013,11(3):907-925
DIA (Dispositivo Inteligente de Alarma, in Spanish) is an AAL (Ambient Assisted Living) system that allows to infer a potential dangerous action of an elderly person living alone at home. This inference is obtained by a specific sensorisation with sensor nodes (portables and fixes) and a reasoning layer embedded in a PC that learns of the users behaviour patterns and advices when actual one differs significantly of the normal patterns. In AAL systems, energy is a limited resource therefore sensor devices need to be properly managed to conserve energy. In this paper, we introduce the design and implementation of innovative and specific mechanisms at the sensory layer middleware which is capable of, first to discriminate spurious motion detections assuming that these signals do not resemble the patterns of real motion detections and, second to reduce the dynamics of messages by a sensor signal processing in order to compress the whole information in one single event. The middleware achieves power saving by modifying the raw information from sensors and adapting it to the predefined semantic of the reasoning layer. It manages the important task of data processing from sensors (raw information), and transfers the pre-processed information into the top layer of reasoning in a more energy efficient way. We also address the trade-off between reducing power consumption and reducing delay for incoming data. We present results from experiments using our implementation of these mechanisms at the middleware that comprises from node firmware to the PC driver. The number of messages of the proposed method with respect to the raw data is reduced by approximately 98.5%. The resources used in the PIR signal processing is reduced by approximately 85%. The resulting delay introduced is small (10–19 s) but system dynamics is slow enough to avoid contextualisation errors or reduction of system performance. We consider these results as very satisfactory. 相似文献
95.
Portilla-Sangabriel Melisa Arzate Sandra Macías-Vargas José-Alberto Ramírez-Zamora Rosa-María 《Topics in Catalysis》2021,64(1-2):181-193
Topics in Catalysis - The use of the magnetic fraction (MF) of a low-grade titanium ore (TO) and two oxidants (H2O2 and NaClO), testing each one separately, were compared in photo-Fenton like... 相似文献
96.
Improving the Stability and Performance of Perovskite Light‐Emitting Diodes by Thermal Annealing Treatment
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97.
Luis Felipe Ramírez-Verduzco Javier Esteban Rodríguez-Rodríguez Alicia del Rayo Jaramillo-Jacob 《Fuel》2012,91(1):102-111
Biodiesel is a renewable bio-fuel derived from natural fats or vegetable oils, and it is considered as a promising alternative to substitute diesel fuels. Cetane number, viscosity, density, and higher heating value are important properties to affect the utilization of biodiesel fuels, because they are involved in the definition of fuel quality and are required as input data for predictive engine combustion models. This work presents the characterization of two biodiesel samples made from beef tallow and soybean oil through their fatty acid methyl esters (FAMEs) profile. Empirical equations were developed to estimate four physical properties of methyl esters; and an average absolute deviation (AAD) of 5.95%, 2.57%, 0.11% and 0.21% for the cetane number, kinematic viscosity, density, and higher heating value were founded. Cetane number, viscosity, and higher heating value increases because of the increase of molecular weight and these physical properties decrease as the number of double bonds increases. Unlike that of above properties, density decreases as molecular weight increases and density increases as the degree of unsaturation increases. Two general mixing rules and five biodiesel samples were used to study the influence of FAMEs over the physical properties of biodiesel. The prediction of the cetane number, kinematic viscosity, density and higher heating value of biodiesel is very close to the experimental values. 相似文献
98.
A. Wendling-Hivet M. Ramón Ferré S. Allaoui R. Nunez S. Loison G. Hivet 《International Journal of Material Forming》2017,10(5):671-683
Cohesion of the fibers network is a key element in numerous manufacturing processes of textile structures and composite parts, because it significantly affects the implementability and the obtained result. However, cohesion remains at the moment an intuitive concept. This paper aims to deal with this concept, first proposing a first interpretation of yarn cohesion. Thanks to this definition, the in-plane shear test is proposed to characterize and measure cohesion. Among many difficulties, it appears to be an interesting way to analyze the cohesion of yarns extracted from 7 different batches and to establish the link between cohesion and implementation in manufacturing processes of Herakles which supports this study. In addition, the phenomenon responsible for the yarn cohesion are tackled and the influence of the yarn constitution is analyzed. 相似文献
99.
Joao Sarraipa Catarina Marques-Lucena Silvia Baldiris Ramón Fabregat Silvana Aciar 《Journal of Intelligent Manufacturing》2016,27(1):83-99
Nowadays, it is commonly known that information systems need an agile capability of handling knowledge. To accomplish this, systems have to have a formal knowledge representation ability supported by specific and advanced reasoning features. This research work proposes a knowledge management approach with the purpose to gather, model and consume community knowledge for specific recommendation commitments. Such approach is accomplished by a semantic lexicon alignment between the various community knowledge assets, to facilitate collaborations establishment between people and systems in an interoperable fashion. Thus, a knowledge base supported by a thesaurus able to represent all the metadata needed to represent and characterize the various community stakeholders’ resources is proposed. The thesaurus represents the lexicon in the domain, which in the ALTER-NATIVA systems is mostly used to support the various e-Learning elements (e.g. courses) and users categorization, sustained by synchronization features to facilitate a constant update of its information. A set of services designed to recommend specific resources in relation to a determined profile of user is provided. Additionally, a discussion about how the ALTER-NATIVA knowledge management approach can be applied to industrial environments is presented. 相似文献
100.
Ram Avtar Jat Ripandeep Singh S.C. Parida A. Das Renu Agarwal K.L. Ramakumar 《International Journal of Hydrogen Energy》2014
In the present study, we have for the first time reported the occupancy of deuterium in a new interstitial site of ZrCoD3 which explain the hydrogen induced disproportionation behavior of ZrCo alloy. We have also reported the effect of Ni substitution on interstitial site occupancy of deuterium in ZrCo1−xNixD3, which in turn explains the improved durability of these Ni substituted deuterides against disproportionation. The crystal structure of the ZrCo1−xNix (x = 0.0, 0.1, 0.2, 0.3) deuterides was investigated by X-ray powder diffraction and neutron diffraction methods. The XRD data reveals a single phase formation for all deuterides with varying Ni content (x). The neutron diffraction study shows that deuterium occupies a new site 8e in addition to 4c2 and 8f1. Additionally, the Zr–D distance in 8e site is shorter than that in ZrD2. Therefore, increase in 8e site occupancy will in turn decreases the durability against disproportionation and vice-versa. Furthermore, the neutron diffraction reveals that occupancy of new 8e site decreases and its Zr–D distance increases with increase in Ni content, which explicate the higher durability against disproportionation for Ni rich compound. 相似文献