179,413 research outputs found
Thermal analysis of GFRP-reinforced continuous concrete decks subjected to top fire
No full textCitation: Hawileh, R. A., & Rasheed, H. A. (2017). Thermal analysis of GFRP-reinforced continuous concrete decks subjected to top fire. International Journal of Advanced Structural Engineering. https://doi.org/10.1007/s40091-017-0168-7This paper presents a numerical study that investigates the behavior of continuous concrete decks doubly reinforced with top and bottom glass fiber reinforced polymer (GFRP) bars subjected to top surface fire. A finite element (FE) model is developed and a detailed transient thermal analysis is performed on a continuous concrete bridge deck under the effect of various fire curves. A parametric study is performed to examine the top cover thickness and the critical fire exposure curve needed to fully degrade the top GFRP bars while achieving certain fire ratings for the deck considered. Accordingly, design tables are prepared for each fire curve to guide the engineer to properly size the top concrete cover and maintain the temperature in the GFRP bars below critical design values in order to control the full top GFRP degradation. It is notable to indicate that degradation of top GFRP bars do not pose a collapse hazard but rather a serviceability concern since cracks in the negative moment region widen resulting in simply supported spans
Interference Management in Software-Defined Mobile Networks
No full textSoftware-Defined Networking promises to deliver more flexible and manageable networks by providing a clear decoupling between control plane and data plane and by implementing the latter in a logically centralized controller. However, if such principles are to be applied also to wireless networks, new primitives and abstractions capable of providing programmers with a global view of the network capturing channel quality and interference must be devised. Moreover, the dynamic radio environment necessitates fast adaptation of physical parameters such as power, modulation and coding schemes. So the wireless SDN abstractions should allow for such adaptations to happen closer to the air interface. In this paper, we present high level abstractions for channel quality, interference and network reconfiguration; the latter permits operations differing in timescales to be carried out at different controller entities. The proposed concepts have been implemented and evaluated over a WiFi-based WLAN. Empirical measurements show that the proposed platform can be used to implement typical WiFi network management tasks such as channel assignment and interference monitoring
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Rasheedia n. nom. (Nematoda, Physalopteridae) for Bulbocephalus Rasheed, 1966 (a homonym of Bulbocephalus Watson, 1916), with description of Rasheedia heptacanthi n. sp. and R. novaecaledoniensis n. sp. from perciform fishes off New Caledonia
No full textInternational audienceThe nematode genus Bulbocephalus Rasheed, 1966 (Nematoda, Physalopteridae) was found to be a homonym of Bulbocephalus Watson, 1916 (Apicomplexa) and, therefore, a new name, Rasheedia n. nom., is proposed to substitute it. Based on light and scanning electron microscope studies of specimens collected from the digestive tract of perciform fishes off New Caledonia, two new species of Rasheedia are described: R. heptacanthi n. sp. from the Cinnabar goatfish Parupeneus heptacanthus (Mullidae) (type host) and Dentex fourmanoiri (Sparidae), and R. novaecaledoniensis n. sp. from the Indian goatfish Parupeneus indicus (Mullidae). These new species are mainly characterized by the number of anterior protrusible oesophageal lobes (two in R. heptacanthi and four in R. novaecaledoniensis), structure of the oesophagus and the lengths of spicules. An amended diagnosis of Rasheedia and a key to species of this genus are provided. Three previously described congeneric species are transferred to Rasheedia as R. deblocki (Le-Van-Hoa, Pham-Ngoc-Khue & Nguyen-Thi-Lien, 1972) n. comb., R. inglisi (Rasheed, 1966) n. comb. and R. pseudupenei (Vassiliadès & Diaw, 1978) n. comb. Cestocephalus Rasheed, 1966 [genus inquirendum], including C. serratus Rasheed, 1966 and C. petterae (Le-Van-Hoa, Pham-Ngoc-Khue & Nguyen-Thi-Lien, 1972) n. comb., should be considered to be separate from Rasheedia. The names Pseudomazzia Bilqees, Ghazi & Haseeb, 2005 and P. macrolabiata Bilqees, Ghazi & Haseeb, 2005, established for a nematode somewhat resembling Rasheedia spp., should be considered nomina dubia. Rasheedia heptacanthi n. sp. and R. novaecaledoniensis n. sp. are the first representatives of the Physalopteridae recorded from fishes in New Caledonian waters
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
VCell: Going Beyond the Cell Abstraction in 5G Mobile Networks
No full textPast years have witnessed the surge of mobile broadband Internet traffic due to the broad adoption of a number of major technical advances in new wireless technologies and consumer electronics. In this respect, mobile networks have greatly increased their availability to meet the exponentially growing capacity demand of modern mobile applications and services. The upcoming scenario in the near future lays down the possibility of a continuum of communications thanks also to the deployment of so called small cells. Conventional cellular networks and the small cells will form the foundation of this pervasive communication system. Therefore, future wireless systems must carry the necessary scalability and seamless operation to accommodate the users and integrate the macro cells and small cells together. In this work we propose the V-Cell concept and architecture. V-Cell is potentially leading to a paradigm shift when approaching the system designs that allows to overcome most of the limitations of physical layer techniques in conventional wireless networks
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
On the Feasibility of Handover over WiFi Backhaul in LTE-based Aerial-Terrestrial Networks
No full textIn this paper, we investigate scenarios where 4G LTE base stations are mounted on balloons raised in the sky for the provision of cellular connectivity and coverage within an area of few kilometers (e.g., scenarios for emergency communications). In this context, the link between the base stations need to be completed using wireless technologies, thus impacting the performance of the X2 logical interface. We propose the adoption of a wireless backhaul link based on WiFi technology. The main contributions of this paper consist in: modeling the LTE handover over a WiFi link; analyzing the binary exponential backoff with a hands-on one-dimensional Markov Chain including a finite number of packet retries as well as accounting for packets corruption due to Rice fading; and showing the average handover latency and handover preparation failure probability, thus proving that WiFi can meet LTE handover constraints in the majority of the investigated cases
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