11 research outputs found
The evaluation of safety in geotechnics according to probabilistic approaches. The bearing capacity of piles
No full textThe Allowable Bearing Capacity of piles is generally evaluated of a deterministic approach based on "Safety Factors" applied to ultimate Base and Shaft bearing capacity. Semiprobabilistic approaches are used in several Codes and in Eurocode 7. At the moment the probabilistic approach is used only in the area of Research.
Examples of the Reliability Index evaluation with respect to the bearing capacity of piles are presented in this paper. The influence of pile length upon reliability is highlighte
L'Universo o storia e descrizione di tutti i popoli, ecloro religioni, costumi usance, ec.
No full textCopia digital. Madrid : Ministerio de Cultura. Subdirección General de Coordinación Bibliotecaria, 2010Contiene : Vol. I : Messico e Guatemala / de Larenaudière ; Perú e Bolivia / Federico Lacroix; A. Falconetti (trad.). -- Vol. II : Colombia e Guiana / C. Famin ; Isole dell'Oceano / Bory di Saint-Vincent ; Regioni Circompolari / Federico Lacroix ; Chili / Cesare Famin ; Patagonia, Terra de Fuoco / Federico Lacroix. -- Vol. III : Stati Uniti d'America / Roux de Rochelle; A. F. Falconetti (trad.). -- Vol. IV : Brasile / Ferdinando Deni
Maximum power point tracking under realistic operating conditions
No full textThe process of tracking the Maximum Power Point (MPP), known as MPPT, becomes problematic under realistic operating conditions due to the potential for there to be more than one local maxima. A very detailed physics based model has been developed for a PV module (in this application a PV roof tile) using the Orcad platform for PSpice. This model is unusual in that it properly represents partial module shading and cell temperature variation. The PV roof tile, based on polycrystalline silicon cells, comprises 18 series-connected cells. In the model, each cell is represented by a standard two-diode sub-model, for which different levels of radiation and cell temperature can be simulated to obtain a realistic overall I-V characteristic for the module. The model can be extended to model any reasonable number of PV roof tiles wired in series and parallel to form a roof array. The IV characteristics calculated in this way using PSpice will be validated using an outdoor PV roof test system located at the University of Strathclyde, Glasgow
The Evaluation of Safety in Geotechnics According to Probabilistic Approaches. The Bearing Capacity of Piles
No full textGibbs-Sampling-based Optimization for the Deployment of Small Cells in 3G Heterogeneous Networks
No full textThe growing popularity of mobile data services has placed great demands for wireless cellular networks to support higher-throughput. One way to meet the rapidly growing traffic demand is through heterogeneous network deployment, which uses a mixture of macro cells and small cells (i.e., micro-/ pico-cells) to further enhance the spatial reuse and thus improves network throughput. In this paper, we propose a Gibbs-Sampling based optimization method for finding the optimal deployment of a given number of small cells in 3G networks. The Gibbs Sampling method intelligently balances two potentially conflicting considerations of placing small-cell BSs close to hotspots and avoiding interference with the macro-cell BSs & other small cell BSs. We show that it converges to the deployment decision with the maximum total system throughput with high probability. We also describe two low-complexity algorithms, the greedy EcNo and the greedy hotspot algorithms. Both algorithms are widely used in industry and can be used as the benchmark for comparing our Gibbs sampling-based (GSB) design. We have conducted extensive simulations based on real traffic traces from the 3G data network. Our numerical results show that the GSB placement outperforms the greedy solutions. The GSB approach produces 10% higher throughput and 30% higher off-loading factor than the greedy solutions. Since the cost of deploying small nodes could be expensive and each city may need a large number of small nodes, the proposed results thus represent significant cost savings when compared to the existing greedy solutions
Scenario driven requirement engineering for design and deployment of mobile communication networks
No full textThe numbers of users and usage of mobile data service are increasing dramatically due to the introduction of smartphones and mobile broadband dongles. For the next decade the mobile broadband market is expected to grow and reach a level where the average data consumption per user is orders of magnitude greater than today. For the telecom industry it is a magnificent challenge to design and deploy these s high-capacity wireless networks taking into account limitations in cost, energy and radio spectrum. The objective of this paper is to highlight the need to consider a multitude of scenarios for the requirements, design and deployment of mobile broad band networks. The R&D has for many years been targeting high peak data rates enabled by improved spectral efficiency, adding more spectrum bands, aggregation of frequency bands and offloading to local wireless networks connected via public fixed phones or broadband. However, many of these features driving the technology development are representative for the conditions in US and Western Europe. The wireless networks also need to be designed assuming deployment in regions in the world where both the availability of spectrum as well as the penetration of fixed phones and broadband are limited. --Mobile broadband networks,cost and capacity,spectrum,deployment strategies,telecommunications,management of technology and R&D,economic development of natural resources
The deep-sea macrobenthos on the continental slope of the northwestern Mediterranean Sea: a quantitative approach
No full textAs part of the ECOMARGE operation (J.G.O.F.S. France), macrobenthic assemblages in the Toulon Canyon were described and quantified on the basis of sampling carried out between 250 and 2000 m depth on the Mediterranean continental slope. Results show that Mediterranean bathyal assemblages are made up mainly of continental shelf eurybathic species. The qualitative and quantitative composition of populations varies with depth on the slope and also varies with station position at equivalent depth, whether on the flanks or in the canyon channel. Various analyses have provided evidence on the factors responsible for this population distribution pattern. No single factor emerges as predominant, but rather a group of factors, which are related to the nature and origin of sediments and more particularly their grain size distribution, geochemical composition and mode of transportation and sedimentation (benthic nepheloid or originating from the water column), act in conjunction to determine the pattern. Comparison with ocean continental slopes shows that in the Mediterranean Sea the absence of tidal current modifies the trophic structure of the macrobenthic assemblages, which are characterized by a dominance of surface and subsurface deposit feeders as compared to a dominance of suspension feeders and carnivores in the upper and median part of the slope in the ocean. Surface dumping of dredge spoil at the canyon head and channelling of waste induces an increase of organic matter and pollutant concentrations in sediment from the upper part of the canyon channel but does not give rise to any marked population degradation
Price competition between a macrocell and a small-cell service provider with limited resources and optimal bandwidth user subscription: a game-theoretical model
No full text[EN] The ever-increasing demand for higher data rates in wireless commutations provides a rationale for small cells deployment. While the physical and technological aspects of small-cell networks have been extensively studied in recent years, the economic analysis has received much less attention. We focus on the economic rationale for a small-cell service provider (SSP) operating a market where an incumbent macrocell service provider (MSP) exists, and competition develops. We analyze such scenario for the case of fixed users by means of Game Theory, specifically through a two-stage game: in the first stage each service provider posts its price according to a Stackelberg game where the MSP is the leader and the SSP is the follower; and, in the second stage, each user chooses both which provider to subscribe to and the optimal amount of bandwidth. A subgame perfect Nash equilibrium is used as a solution concept, and it is derived analytically. We show that the SSP has an incentive to operate in the market and its profit gets higher as SSP's resources increase. Furthermore, users benefit from SSP's operation, which may provide a rationale for a regulatory authority to grant the SSP access to the market, despite the fact that MSP's profit is harmed. Finally, we identify two modes of operation of the system, which depend on the SSP coverage: one where SSP's deployment is limited and the MSP strategy is not affected by SSP competition and takes only the users outside the SSP coverage; and another, where the SSP covers a large area and the MSP competes against the SSP taking a fraction of the users inside the small cells.This work was supported by the Spanish Ministry of Economy and Competitiveness through Grants TIN2013-47272-C2-1-R and BES-2011-045551.Romero-Chavarro, JC.; Guijarro, L.; Pla, V.; Vidal Catalá, JR. (2018). Price competition between a macrocell and a small-cell service provider with limited resources and optimal bandwidth user subscription: a game-theoretical model. Telecommunication Systems. 67(2):195-209. https://doi.org/10.1007/s11235-017-0331-2S195209672Andrews, J. G., Claussen, H., Dohler, M., Rangan, S., & Reed, M. C. (2012). Femtocells: Past, present, and future. IEEE Journal on Selected Areas in Communications, 30(3), 497–508. doi: 10.1109/JSAC.2012.120401 .Barron, E. N. (2013). Game theory: An introduction (Vol. 2). John Wiley & Sons.Chandrasekhar, V., Andrews, J. G., & Gatherer, A. (2008). Femtocell networks: A survey. IEEE Communications Magazine, 46(9), 59–67. doi: 10.1109/MCOM.2008.4623708 .Duan, L., Huang, J., & Shou, B. (2010). Competition with dynamic spectrum leasing. In: IEEE Symposium on New Frontiers in Dynamic Spectrum (DySPAN), pp. 1–11. doi: 10.1109/DYSPAN.2010.5457903 .Duan, L., Huang, J., & Shou, B. (2013). Economics of femtocell service provision. IEEE Transactions on Mobile Computing, 12, 2261–2273.Duan, L., Shou, B., & Huang, J. (2012). Capacity allocation and pricing strategies for wireless femtocell services. CoRR abs/1205.1196. http://arxiv.org/abs/1205.1196 .El-Atty, S. M. A., & Gharsseldien, Z. M. (2016). Backhaul metro cell-based guard channel in femto/macro cellular heterogeneous networks. Telecommunication Systems, 61(4), 645–658. doi: 10.1007/s11235-015-0059-9 .Federal Communications Commission. (2003). Report and Order (FCC 05-57): Facilitating opportunities for flexible, efficient and reliable spectrum agile radio technologie. ET Docket No. 03–108.Goldsmith, A. (2005). Wireless communications. Cambridge: Cambridge University Press.Guijarro, L., Pla, V., Vidal, J. R., & Martinez-Bauset, J. (2012). Femtocell operator entry decision with spectrum bargaining and service competition. IEEE Communications Letters, 16(12), 1976–1979. doi: 10.1109/LCOMM.2012.101712.121645 .Gupta, A., & Jha, R. K. (2015). A survey of 5G network: Architecture and emerging technologies. IEEE Access, 3, 1206–1232. doi: 10.1109/ACCESS.2015.2461602 .Fu, H. L., Lin, P., & Lin, Y. B. (2013). Reducing signaling overhead for femtocell/macrocell networks. IEEE Transactions on Mobile Computing, 12(8), 1587–1597. doi: 10.1109/TMC.2012.132 .Kang, X., Zhang, R., & Motani, M. (2012). Price-based resource allocation for spectrum-sharing femtocell networks: A stackelberg game approach. IEEE Journal on Selected Areas in Communications, 30(3), 538–549. doi: 10.1109/JSAC.2012.120404 .Landstrom, S., Furuskar, A., Johansson, K., Falconetti, L., & Kronestedt, F. (2011). Heterogeneous networks increasing cellular capacity. Ericsson Review, 89(3), 4–9.Ogawa, K., Hattori, T., & Yoshida, H. (1994). Optimum multi-layered cell architecture for personal communication systems with high degree of mobility. In: IEEE 44th Vehicular Technology Conference, pp. 644–648.Romero, J., & Guijarro, L. (2013). Competition between primary and secondary operators with spectrum leasing and optimal spectrum subscription by users. In: IEEE 24th International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC Workshops), pp. 143–147. doi: 10.1109/PIMRCW.2013.6707853 .Sandler, K. (2009, February). House calls: Femtocells promise to boost the cellphone signals inside your home. The Wall Street Journal.Sengupta, S., & Chatterjee, M. (2009). An economic framework for dynamic spectrum access and service pricing. IEEE/ACM Transactions on Networking, 17(4), 1200–1213. doi: 10.1109/TNET.2008.2007758 .Shetty, N., Parekh, S., & Walrand, J. (2009). Economics of femtocells. In: IEEE Global Telecommunications Conference, GLOBECOM, pp. 1–6. doi: 10.1109/GLOCOM.2009.5426129 .LaVallee, A. (2009). AT&T to New York and San Francisco: We are working on it. The Wall Street Journal.Wardrop, J. (1952). Some theoretical aspects of road traffic research. Proceedings of the Institute of Civil Engineers, 1, 325–378.Yi, Y., Zhang, J., Zhang, Q., & Jiang, T. (2012). Spectrum leasing to femto service provider with hybrid access. In: Proceedings IEEE INFOCOM, pp. 1215–1223. doi: 10.1109/INFCOM.2012.6195482 .Yun, S., Yi, Y., Cho, D. H., & Mo, J. (2011). Open or close: On the sharing of femtocells. In: Proceedings IEEE INFOCOM, pp. 116–120. doi: 10.1109/INFCOM.2011.5934894 .Zhang, H., Huang, L., Xu, H., & Sun, Q. (2015). Cooperative optimal pricing for stochastic access control in overlaid radio access networks. Telecommunication Systems, 60(1), 3–16.Zhu, K., Hossain, E., & Niyato, D. (2014). Pricing, spectrum sharing, and service selection in two-tier small cell networks: A hierarchical dynamic game approach. IEEE Transactions on Mobile Computing, 13(8), 1843–1856. doi: 10.1109/TMC.2013.96
A MULTI-CASE STUDY OF THREE FLORIDA COMMUNITY COLLEGES OFFERING APPLIED BACCALAUREATE DEGREE PROGRAMS AND HOW THE PROGRAMS ASSIST STUDENTS WITH THEIR POSTSECONDARY NEEDS
No full textThis study examined the trend of community colleges offering baccalaureate degrees that address workforce needs. Employers are looking for better-educated employees and in many cases require a baccalaureate degree to even consider an individual for a job opening. Florida’s legislature has been an effective facilitator in supporting the development of directly conferred baccalaureate degrees in 24 of the state’s 28 community colleges. Four-year institutions offer traditional degrees, but sometimes are not able to accommodate all the students requiring admission. In these cases, community colleges are meeting some of these specific student needs by offering these practice-related programs such as nursing. Some of these programs include part-time campus study and online study for a hybrid delivery system that has not been embraced as readily by some of the four-year institutions. Online study is believed to allow more students the ability to obtain a bachelor’s degree, especially the non-traditional place-bound students.
This study was conducted to provide a better understanding of what it means to offer directly conferred baccalaureate degree programs in community colleges, how each institution went through the process of deciding this option for the particular programs offered, what internal and external issues were resolved, how the funding to start up the programs was obtained, how it affected the other programs at the institution, how the bachelor of applied science programs satisfy student needs and, finally, what the policy implications of offering baccalaureate degrees were at each institution.
This information will be important to other state’s legislators and community college administrators in determining the implications of offering baccalaureate degrees, and how it may meet their needs in serving the many students that rely on these institutions for their postsecondary education
Meiobenthos of the discovery Bay Lagoon, Jamaica, with an emphasis on nematodes.
No full textPhDSediment granulometry, microphytobenthos and meiobenthos were investigated
at five habitats (white and grey sands, backreef border, shallow and deep
thalassinid ghost shrimp mounds) within the western lagoon at Discovery Bay,
Jamaica. Habitats were ordinated into discrete stations based on sediment
granulometry. Microphytobenthic chlorophyll-a ranged between 9.5- and 151.7
mg m-2 and was consistently highest at the grey sand habitat over three sampling
occasions, but did not differ between the remaining habitats. It is suggested that
the high microphytobenthic biomass in grey sands was related to upwelling of
nutrient rich water from the nearby main bay, and the release and excretion of
nutrients from sediments and burrowing heart urchins, respectively. Meiofauna
abundance ranged from 284- to 5344 individuals 10 cm-2 and showed spatial
differences depending on taxon. Of 22 higher taxa recorded, nematodes
dominated followed by copepods, together accounting for ~80 % of all
individuals. Both taxa were most abundant in grey sands, suggesting a response,
either directly or indirectly, to the high microphyte biomass. Significant withinhabitat
spatial variability in both meio- and microphytobenthos was found,
causes of which are discussed. Nematode feeding groups varied between
habitats. Fine white sands and both thalassinid mound habitats were dominated
by non-selective deposit feeders. Slender and plump nematode morphotypes
were found, yet the plump morphotype was largely absent from coarse sands
subjected to high wave swash at the backreef border habitat. Here, nematode
lengths were significantly higher than at other habitats. Nematode biomass
spectra differed significantly between habitats, with a shift in peak biomass
values towards larger size classes in the disturbed sediments. It is suggested that
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longer and larger nematodes represent an adaptation to sediment disturbance,
helping to prevent being displaced from the benthos by hydrodynamic forces and
bioturbation
