30 research outputs found

    Resource Allocation Energy Efficient Algorithm for H-CRAN in 5G

    Get PDF
    In today's generation, the demand for data rates has also increased due to the rapid surge in the number of users. With this increasing growth, there is a need to develop the next fifth generation network keeping in mind the need to replace the current 4G cellular network. The fifth generation (5G) design in mobile communication technology has been developed keeping in mind all the communication needs of the users. Heterogeneous Cloud Radio Access Network (H-CRAN) has emerged as a capable architecture for the newly emerging network infrastructure for energy efficient networks and high data rate enablement. It is considered as the main technology. Better service quality has been achieved by developing small cells into macro cells through this type of network. In addition, the reuse of radio resources is much better than that of homogeneous networks. In the present paper, we propose the H-CRAN energy-efficient methods. This energy-efficient algorithm incorporates an energy efficient resource allocation management design to deal to heterogeneous cloud radio access networks in 5G. System throughput fulfillment is elevating by incorporating an efficient resource allocation design by the energy consumption model. The simulation results have been demonstrated by comparing the efficiency of the introduced design with the existing related design

    Parametric Study of CPT Resonance in Rubidium Vapor Cell for Application in Atomic Clock

    Get PDF
    The performance of Coherent Population Trapping (CPT) based atomic clocks primarily depends on the characteristics of CPT resonance. We have performed experiments to study and optimize the characteristics of CPT resonance in 87Rb atoms by measuring its contrast and full-width-at-half maximum (FWHM) as function of laser excitation and temperature of atomic vapor cells with different dimensions. A four-level atomic model is used to simulate CPT resonance characteristics along the length of atomic vapor cell. The model incorporates scaling law to understand collision dynamics in cells with different radius for a range of laser excitation intensities and the results are compared with experimental data. The quality figure, calculated from the measured values of FWHM and contrast, decreases with increase in laser intensity and improves in cells with higher dimension (radius). The optimum temperature corresponding to maximum quality figure varies with laser excitation intensity as well as cell dimension. The underlying collision dynamics and density effects that are responsible for the observed resonance characteristics are discussed

    Vulnerability of loggerhead turtle eggs to the presence of clay and silt on nesting beaches

    No full text
    Sea turtle nests usually suffer a high mortality on important nesting grounds. Understanding the main factors that influence hatching success and productivity on important rookeries of endangered populations is essential to properly manage and protect them. The amount of clay can be high on some nesting beaches and could affect egg incubation. In the main loggerhead rookery in the Eastern Atlantic (Boa Vista, Cape Verde), clays and silts are very common on near 10% of the main nesting beaches, and turtles do not avoid clay substrates when they lay their eggs. Nests incubated on sandy substrates rich on clay and silt had a very high mortality. The same occurs on nests with the eggs stained with clay and incubated in sand free of clay. The eggs experimentally incubated with a covering layer of clay (30%, 50% and 80% of the eggshell) suffered an important loss of water, which in the extreme cases was irreversible, causing the death of the embryos. 75% of the eggs with 80% of their eggshells covered with clay died, while the mortality rate of the control eggs was only 25%. The salt content of the clay/silt seems not to be responsible for the egg dehydration and death. The hatchlings born from eggs with only 30% of the eggshell covered by clay were slower that those born from control eggs. Substrates with a significant presence of clay/silt can seriously disrupt embryonic development, reducing the emergence success of nests and should be avoided on nest relocation programs.We would like to thank the Ministry of the Environment of the Regional Government of Andalusia, the Regional Government of the Canary Islands and the Fuerteventura Inter-Island Council (Cabildo de Fuerteventura) for funding this research. We thank the General Directorate of Environment of Cape Verde (Direcção Geral do Ambiente), the Boa Vista municipal chamber (Câmara Municipal da Boavista), the Canary Institute of Marine Sciences and the University of Las Palmas de Gran Canaria for their help. We are grateful to Fernando Madrid for the soil sample analysis in the Institute of Natural Resources and Agrobiology of Seville (IRNAS), to the Cape Verdean NGO Cabo Verde Natura 2000 and to its staff for their logistical support, to all volunteers who took part in the collection of nests and the preparation of the experiments and, especially, to E

    Experimental and Monte Carlo study of the effect of the presence of dry air, cortical bone inhomogeneities and source position on dose distribution of the mHDR-v2 source

    No full text
    Background: Recently it was data wise established that there is a considerable dose difference due to source position from the surface of the patient, and due to the presence of inhomogeneities. Aim: It aims at to find out the dose difference due to source position, and inhomogenieties in water phantom of high dose rate (HDR) 192 Ir mHDR-v2 source by experiment and by Monte Carlo (MC) simulation GEANT4 code. Materials and Methods: The measured study of the source was done using an in-air ionization chamber, water phantom while the calculated study was done by modeling the water phantom and its water, inhomogeneities, position of source, and points of calculation. Results: The measured and calculated dose differences are 5.48 to 6.46% and 5.43 to 6.44% respectively higher in the presence of dry air and 4.40 to 4.90% and 4.38 to 4.88% respectively lower in the presence of cortical bone. However, for the study of the effect of source position on dose distribution, when the source was positioned at a 1 cm distance from the surface of water phantom, the near points between 1 cm and 2 cm are 2 to 3.5% and 2.1-3.7% underdose and for distant points from 3 cm to 8 cm from the source are 4 to 15% and 4.1 to 15.8% underdose for measured and calculated studies, respectively, to the dose when the source was positioned at midpoint of water phantom. Conclusion: These results can be used in the treatment planning system

    Monte Carlo study of dosimetric parameters and dose distribution effect of inhomogeneities and source position of GammaMed Plus source

    No full text
    Background: The conventional treatment planning system (TPS) gives analytical calculations with approximately ±15?20% dose uncertainty, which may lead to over exposure of critical organs or under dose of target as well as the presence of inhomogeneities, and the position of source affects the exact dose calculation like in breast and intraluminal brachytherapy. Aim: To obtain dose distribution parameters of GammaMed Plus high dose rate (HDR) 192 Ir source using Monte Carlo (MC) EGSnrc and GEANT4 codes as well as to find the effect on dose distribution due to source position, and due to presence of air and cortical bone by using MC GEANT4 code, and to find the similarity of both studies with any past study of any HDR brachytherapy source for either as input to TPS or verification of TPS calculations. Settings and Design: It is done using different software of the computer, e.g., excel, MS word, etc. Materials and Methods: The source, source position for different studies, water phantom, water characteristics, points of measurements, air and cortical bone inhomogeneities, and position of inhomogeneities were simulated. Statistical Analysis Used: For uncertainties calculation, mean and probability are used. Results: The calculated dose rate constant, radial dose function, and 2D anisotropy function of the source show similarity with published data. Calculated dose distribution differences due to presence of air and cortical bone, and position of source in water phantom also show similarity with published data. Conclusion: These results can either be implemented in TPS or can be used for verification of TPS calculations

    Evaluating loggerhead sea turtle (Caretta caretta) bycatch in the small-scale fisheries of Cabo Verde

    No full text
    The incidental or target capture of sea turtles by small-scale fisheries (SSF) has been receiving increasing attention in recent years due to its high impact. Here, we evaluated the impact of the SSF on sea turtles in Cabo Verde, which hosts the largest rookery of the endangered Eastern Atlantic loggerhead turtle (Caretta caretta) population. This is the most comprehensive study evaluating the impact of SSF on sea turtles in the Cabo Verde Archipelago involving more than 85% of boats and more than 20% of the fishermen registered in the archipelago. Between the years of 2011 and 2014, 763 artisanal fishermen were interviewed at all the main ports and fishing communities of seven islands. Artisanal fishermen reported a mean annual capture of 1.5 turtles per boat indicating that a minimum of 1675 sea turtles could be landed per year in this fishing sector alone, with 65% in Santiago Island (which host the country's capital, Praia). Most captures (95.7%) occurred from May to September and coincided with the loggerhead turtle nesting season. These results suggest a severe impact of the SSF on adult loggerheads turtles in Cabo Verde as well as green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) juvenile turtles. To mitigate this impact, measures such as revising the current legislation for fisheries, the supervision and control of landings, especially in the most remote ports of the Archipelago, the regulation of the SSF during the nesting season around the main nesting areas, awareness-raising campaigns, sustainable activities, and alternative sources of income in fishing communities are recommended.info:eu-repo/semantics/publishedVersio

    Parametric Study of CPT Resonance in Rubidium Vapor Cell for Application in Atomic Clock

    No full text
    489-496The performance of Coherent Population Trapping (CPT) based atomic clocks primarily depends on the characteristics of CPT resonance. We have performed experiments to study and optimize the characteristics of CPT resonance in 87Rb atoms by measuring its contrast and full-width-at-half maximum (FWHM) as function of laser excitation and temperature of atomic vapor cells with different dimensions. A four-level atomic model is used to simulate CPT resonance characteristics along the length of atomic vapor cell. The model incorporates scaling law to understand collision dynamics in cells with different radius for a range of laser excitation intensities and the results are compared with experimental data. The quality figure, calculated from the measured values of FWHM and contrast, decreases with increase in laser intensity and improves in cells with higher dimension (radius). The optimum temperature corresponding to maximum quality figure varies with laser excitation intensity as well as cell dimension. The underlying collision dynamics and density effects that are responsible for the observed resonance characteristics are discussed
    corecore