128 research outputs found

    Enhancing Wireless Sensor Networks Routing Protocols based on Cross Layer Interaction

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    Wireless sensor networks aim to develop a smart city based on sensing environment. The routing protocols of wireless sensor networks is important to transfer the data in smart cities since sensor nodes have limited power and transmission range. The aim of this research is to enhance wireless sensor networks routing protocols based on proposed cross-layer interaction between physical layer and network layer also a proposed routing table information of wireless sensor nodes is developed to consider the transmission power of neighbor’s nodes to determine the next hop. Cross-layer interaction provides a useful information and effective adaptation for WSN routing protocols. As a result, the proposed routing protocol shows an improvement in network performance when number of intermediate nodes are minimized

    MIXED CONVECTION FROM ELECTRONIC EQUIPMENT COMPONENT AT DIFFERENT POSITION AN ENCLOUSER BY PRIMITIVE VARABILS METHOD

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    A numerical study of mixed convtion cooling of heat dissipating electronic component, located in a rectangular enclosure, and cooled by an external through flow of air is carried out.A conjugate problem is solved by primitive variables method, describing the flow and thermal fields in air .The interaction between the components is of interest here, depending on their relative placement in the enclosure, and different configuration are considered. for Re=100 laminar, steady flow is predicted for up to Gr/Re2 =25 according to heat source location in the enclosure. The mixed convection regime, where the buoyancy effects are comparable to the forced flow, occurs at values of Gr/Re2 between 0.01 and 25 .The results are of values in search for suitable placement of electronic components in an enclosed region for an effective heat removal. In general, it appears that the location of the source on the left vertical wall is the most favorable in terms of cooling. Laminar results are predicted up for up to Gr = 2.5*105 for all configurations studie

    NUMERICAL AND EXPERIMENTAL INVESTIGATION ON THE EFFECT OF RESTRICTION SHAPE ON CHARACTERISTICS OF AIRFLOW IN A SQUARE DUCT

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     Experimental and numerical investigation has been under taken to study turbulent flow of air through duct using restriction in different shapes and positions for Reynolds numbers ranges of (8.2x104 → 5.6x104).The numerical approach used in this work is the finite volume method for solution of elliptic partial differential equation for the modeling of turbulent (k-) model as well as wall function concept near the wall which was used to take the turbulent effects into consideration have been employed.The experimental test rigs were constructed from Perspex, and a fivehole pressure probe was used to measure the three component of air flow velocity vector in space.The results show that the total pressure drop depends on the shape and position of the restriction, and the pressure drop coefficient due to the restriction shape and position (kR) depends on two parameters; blockage area ratio (Ab) and the ratio between wetted perimeter to the free remainder perimeter (pe/Pe) and dose not depend on the Reynolds number ( for the same blockage area ratio Ab if the pe/Pe increases 40%, the coefficient kR increases 7% , and for the same pe/Pe, if the blockage area ratio increases 50% ,the coefficient kR increases 10%). But the pressure drop coefficient due to the friction (Cf) is a function of Reynolds.

    Critically ill patients with diabetes and Middle East respiratory syndrome:a multi-center observational study

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    Background: Diabetes is a risk factor for infection with coronaviruses. This study describes the demographic, clinical data, and outcomes of critically ill patients with diabetes and Middle East Respiratory Syndrome (MERS).Methods: This retrospective cohort study was conducted at 14 hospitals in Saudi Arabia (September 2012–January 2018). We compared the demographic characteristics, underlying medical conditions, presenting symptoms andsigns, management and clinical course, and outcomes of critically ill patients with MERS who had diabetes compared to those with no diabetes. Multivariable logistic regression analysis was performed to determine ifdiabetes was an independent predictor of 90-day mortality.Results: Of the 350 critically ill patients with MERS, 171 (48.9%) had diabetes. Patients with diabetes were more likely to be older, and have comorbid conditions, compared to patients with no diabetes. They were more likely topresent with respiratory failure requiring intubation, vasopressors, and corticosteroids. The median time to clearance of MERS-CoV RNA was similar (23 days (Q1, Q3: 17, 36) in patients with diabetes and 21.0 days (Q1, Q3: 10, 33) in patients with no diabetes). Mortality at 90 days was higher in patients with diabetes (78.9% versus 54.7%, p <0.0001). Multivariable regression analysis showed that diabetes was an independent risk factor for 90-day mortality(odds ratio, 2.09; 95% confidence interval, 1.18–3.72).Conclusions: Half of the critically ill patients with MERS have diabetes; which is associated with more severe disease. Diabetes is an independent predictor of mortality among critically patients with MERS

    Critically ill patients with diabetes and Middle East respiratory syndrome:a multi-center observational study

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    Background: Diabetes is a risk factor for infection with coronaviruses. This study describes the demographic, clinical data, and outcomes of critically ill patients with diabetes and Middle East Respiratory Syndrome (MERS).Methods: This retrospective cohort study was conducted at 14 hospitals in Saudi Arabia (September 2012–January 2018). We compared the demographic characteristics, underlying medical conditions, presenting symptoms andsigns, management and clinical course, and outcomes of critically ill patients with MERS who had diabetes compared to those with no diabetes. Multivariable logistic regression analysis was performed to determine ifdiabetes was an independent predictor of 90-day mortality.Results: Of the 350 critically ill patients with MERS, 171 (48.9%) had diabetes. Patients with diabetes were more likely to be older, and have comorbid conditions, compared to patients with no diabetes. They were more likely topresent with respiratory failure requiring intubation, vasopressors, and corticosteroids. The median time to clearance of MERS-CoV RNA was similar (23 days (Q1, Q3: 17, 36) in patients with diabetes and 21.0 days (Q1, Q3: 10, 33) in patients with no diabetes). Mortality at 90 days was higher in patients with diabetes (78.9% versus 54.7%, p <0.0001). Multivariable regression analysis showed that diabetes was an independent risk factor for 90-day mortality(odds ratio, 2.09; 95% confidence interval, 1.18–3.72).Conclusions: Half of the critically ill patients with MERS have diabetes; which is associated with more severe disease. Diabetes is an independent predictor of mortality among critically patients with MERS

    A massive hot Jupiter orbiting a metal-rich early-M star discovered in the TESS full frame images

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    Observations and statistical studies have shown that giant planets are rare around M dwarfs compared with Sun-like stars. The formation mechanism of these extreme systems remains under debate for decades. With the help of the TESS mission and ground based follow-up observations, we report the discovery of TOI-4201b, the most massive and densest hot Jupiter around an M dwarf known so far with a radius of 1.22±0.04 RJ1.22\pm 0.04\ R_J and a mass of 2.48±0.09 MJ2.48\pm0.09\ M_J, about 5 times heavier than most other giant planets around M dwarfs. It also has the highest planet-to-star mass ratio (q∼4×10−3q\sim 4\times 10^{-3}) among such systems. The host star is an early-M dwarf with a mass of $0.61\pm0.02\ M_{\odot}andaradiusof and a radius of 0.63\pm0.02\ R_{\odot}.Ithassignificantsuper−solarironabundance([Fe/H]=. It has significant super-solar iron abundance ([Fe/H]=0.52\pm 0.08$ dex). However, interior structure modeling suggests that its planet TOI-4201b is metal-poor, which challenges the classical core-accretion correlation of stellar-planet metallicity, unless the planet is inflated by additional energy sources. Building on the detection of this planet, we compare the stellar metallicity distribution of four planetary groups: hot/warm Jupiters around G/M dwarfs. We find that hot/warm Jupiters show a similar metallicity dependence around G-type stars. For M dwarf host stars, the occurrence of hot Jupiters shows a much stronger correlation with iron abundance, while warm Jupiters display a weaker preference, indicating possible different formation histories.Comment: 21 pages, 11 figures, 4 tables, submitted to A

    Three long period transiting giant planets from TESS

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    We report the discovery and orbital characterization of three new transiting warm giant planets. These systems were initially identified as presenting single transit events in the light curves generated from the full frame images of the Transiting Exoplanet Survey Satellite (TESS). Follow-up radial velocity measurements and additional light curves were used to determine the orbital periods and confirm the planetary nature of the candidates. The planets orbit slightly metal-rich late F- and early G-type stars. We find that TOI 4406b has a mass of MPM_P= 0.30 ±\pm 0.04 MJM_J , a radius of RPR_P= 1.00 ±\pm 0.02 RJR_J , and a low eccentricity orbit (e=0.15 ±\pm 0.05) with a period of P= 30.08364 ±\pm 0.00005 d . TOI 2338b has a mass of MPM_P= 5.98 ±\pm 0.20 MJM_J , a radius of RPR_P= 1.00 ±\pm 0.01 RJR_J , and a highly eccentric orbit (e= 0.676 ±\pm 0.002 ) with a period of P= 22.65398 ±\pm 0.00002 d . Finally, TOI 2589b has a mass of MPM_P= 3.50 ±\pm 0.10 MJM_J , a radius of RPR_P= 1.08 ±\pm 0.03 RJR_J , and an eccentric orbit (e = 0.522 ±\pm 0.006 ) with a period of P= 61.6277 ±\pm 0.0002 d . TOI 4406b and TOI 2338b are enriched in metals compared to their host stars, while the structure of TOI 2589b is consistent with having similar metal enrichment to its host star.Comment: 24 pages, 16 figures, accepted in A

    TOI-199 b: A well-characterized 100-day transiting warm giant planet with TTVs seen from Antarctica

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    We present the spectroscopic confirmation and precise mass measurement of the warm giant planet TOI-199 b. This planet was first identified in TESS photometry and confirmed using ground-based photometry from ASTEP in Antarctica including a full 6.5 \,h long transit, PEST, Hazelwood, and LCO; space photometry from NEOSSat; and radial velocities (RVs) from FEROS, HARPS, CORALIE, and CHIRON. Orbiting a late G-type star, TOI-199\,b has a 104.854−0.002+0.001 d\mathrm{104.854_{-0.002}^{+0.001} \, d} period, a mass of 0.17±0.02 MJ\mathrm{0.17\pm0.02 \, M_J}, and a radius of 0.810±0.005 RJ\mathrm{0.810\pm0.005 \, R_J}. It is the first warm exo-Saturn with a precisely determined mass and radius. The TESS and ASTEP transits show strong transit timing variations, pointing to the existence of a second planet in the system. The joint analysis of the RVs and TTVs provides a unique solution for the non-transiting companion TOI-199 c, which has a period of 273.69−0.22+0.26 d\mathrm{273.69_{-0.22}^{+0.26} \, d} and an estimated mass of 0.28−0.01+0.02 MJ\mathrm{0.28_{-0.01}^{+0.02} \, M_J}. This period places it within the conservative Habitable Zone.Comment: 33 pages, 23 figures. Accepted for publication in A

    Migration and Evolution of giant ExoPlanets (MEEP) I: Nine Newly Confirmed Hot Jupiters from the TESS Mission

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    Hot Jupiters were many of the first exoplanets discovered in the 1990s, but in the decades since their discovery, the mysteries surrounding their origins remain. Here, we present nine new hot Jupiters (TOI-1855 b, TOI-2107 b, TOI-2368 b, TOI-3321 b, TOI-3894 b, TOI-3919 b, TOI-4153 b, TOI-5232 b, and TOI-5301 b) discovered by NASA's TESS mission and confirmed using ground-based imaging and spectroscopy. These discoveries are the first in a series of papers named the Migration and Evolution of giant ExoPlanets (MEEP) survey and are part of an ongoing effort to build a complete sample of hot Jupiters orbiting FGK stars, with a limiting Gaia GG-band magnitude of 12.5. This effort aims to use homogeneous detection and analysis techniques to generate a set of precisely measured stellar and planetary properties that is ripe for statistical analysis. The nine planets presented in this work occupy a range of masses (0.55 Jupiter masses (MJ_{\rm{J}}) << MP_{\rm{P}} << 3.88 MJ_{\rm{J}}) and sizes (0.967 Jupiter radii (RJ_{\rm{J}}) << RP_{\rm{P}} << 1.438 RJ_{\rm{J}}) and orbit stars that range in temperature from 5360 K << Teff << 6860 K with Gaia GG-band magnitudes ranging from 11.1 to 12.7. Two of the planets in our sample have detectable orbital eccentricity: TOI-3919 b (e=0.259−0.036+0.033e = 0.259^{+0.033}_{-0.036}) and TOI-5301 b (e=0.33−0.10+0.11e = 0.33^{+0.11}_{-0.10}). These eccentric planets join a growing sample of eccentric hot Jupiters that are consistent with high-eccentricity tidal migration, one of the three most prominent theories explaining hot Jupiter formation and evolution.Comment: 35 pages, 7 tables, and 14 figures. Submitted to AAS Journals on 2023 Dec 2

    Global, regional, and national comparative risk assessment of 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks, 1990–2015: a systematic analysis for the Global Burden of Disease Study 2015

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    Background The Global Burden of Diseases, Injuries, and Risk Factors Study 2015 provides an up-to-date synthesis of the evidence for risk factor exposure and the attributable burden of disease. By providing national and subnational assessments spanning the past 25 years, this study can inform debates on the importance of addressing risks in context. Methods We used the comparative risk assessment framework developed for previous iterations of the Global Burden of Disease Study to estimate attributable deaths, disability-adjusted life-years (DALYs), and trends in exposure by age group, sex, year, and geography for 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks from 1990 to 2015. This study included 388 risk-outcome pairs that met World Cancer Research Fund-defi ned criteria for convincing or probable evidence. We extracted relative risk and exposure estimates from randomised controlled trials, cohorts, pooled cohorts, household surveys, census data, satellite data, and other sources. We used statistical models to pool data, adjust for bias, and incorporate covariates. We developed a metric that allows comparisons of exposure across risk factors—the summary exposure value. Using the counterfactual scenario of theoretical minimum risk level, we estimated the portion of deaths and DALYs that could be attributed to a given risk. We decomposed trends in attributable burden into contributions from population growth, population age structure, risk exposure, and risk-deleted cause-specifi c DALY rates. We characterised risk exposure in relation to a Socio-demographic Index (SDI).Background The Global Burden of Diseases, Injuries, and Risk Factors Study 2015 provides an up-to-date synthesis of the evidence for risk factor exposure and the attributable burden of disease. By providing national and subnational assessments spanning the past 25 years, this study can inform debates on the importance of addressing risks in context. Methods We used the comparative risk assessment framework developed for previous iterations of the Global Burden of Disease Study to estimate attributable deaths, disability-adjusted life-years (DALYs), and trends in exposure by age group, sex, year, and geography for 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks from 1990 to 2015. This study included 388 risk-outcome pairs that met World Cancer Research Fund-defi ned criteria for convincing or probable evidence. We extracted relative risk and exposure estimates from randomised controlled trials, cohorts, pooled cohorts, household surveys, census data, satellite data, and other sources. We used statistical models to pool data, adjust for bias, and incorporate covariates. We developed a metric that allows comparisons of exposure across risk factors—the summary exposure value. Using the counterfactual scenario of theoretical minimum risk level, we estimated the portion of deaths and DALYs that could be attributed to a given risk. We decomposed trends in attributable burden into contributions from population growth, population age structure, risk exposure, and risk-deleted cause-specifi c DALY rates. We characterised risk exposure in relation to a Socio-demographic Index (SDI)
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