164 research outputs found
A Trust Model Based on Cloud Model and Bayesian Networks
Abstractthe Internet has been becoming the most important infrastructure for distributed applications which are composed of online services. In such open and dynamic environment, service selection becomes a challenge. The approaches based on subjective trust models are more adaptive and efficient than traditional binary logic based approaches. Most well known trust models use probability or fuzzy set theory to hold randomness or fuzziness respectively. Only cloud model based models consider both aspects of uncertainty. Although cloud model is ideal for representing trust degrees, it is not efficient for context aware trust evaluation and dynamic updates. By contrast, Bayesian network as an uncertain reasoning tool is more efficient for dynamic trust evaluation. An uncertain trust model that combines cloud model and Bayesian network is proposed in this paper
The measurement of masses of OB-type stars from LAMOST DR5
The measurements of masses and luminosities of massive stars play an
important role in understanding the formation and evolution of their host
galaxies. In this work, we present the measurement of masses and luminosities
of 2,946 OB-type stars, including 78 O-type stars and 2,868 B-type stars, based
on their stellar parameters (effective temperature, surface gravity, and
metallicity) and PARSEC isochrones model. Our results show that the median mass
and luminosity of the 2,946 OB-type stars are 5.4 M and
log(L/L)=3.2 with the median relative error of 21.4 and 71.1,
respectively. A good agreement between our results estimated by using our
method and those derived by using the orbital motions of binary stars from the
literature is found for some B-type stars. In addition, we also fit the
mass-luminosity relation of B-type stars by using our derived mass and the
luminosity from DR3.Comment: 12 pages, 10 figures, 1 table, accepted for publication in ApJ
Numerical analysis on aerodynamic characteristics of short cylindrical terminal-sensitive bullet
The flow-induced lateral vibration phenomenon of the terminal sensitive bullets (TSB) when it is dispersed by the airborne distributor is taken as the research background. Based on the Fluent, the flow around a rotating short cylindrical TSB (L/D < 1) is simulated and analyzed varying with relative rotation velocity at high Re number (1×105 ≤ Re ≤ 3×106). The simulation results show that the flow field structure of the short cylinder with two free ends is different from the symmetry of the short cylindrical flow field with one free end, and there is no horseshoe vortex. Compared to the long cylinder with double free ends, the Cd of the short cylinder is more sensitive to the change of Re. With the increase of Re, the Cd of the short cylinder decreases, and the value is between the infinite cylinder and the sphere in the non-critical region. When the short cylinder rotates at the angular velocity ω, the top vortex bends and deforms to a ‘C’ shape on the leeward side where the fluid is accelerated. Due to the periodic disturbance of the detector, the aerodynamic coefficient of the rotating TSB is periodically vibrated. In a single cycle, the waveform of the cd shows a ‘W’ shape, and the waveform of the cl is ‘M’
Prevalence of hyperglycemia among adults with newly diagnosed HIV/AIDS in China
BACKGROUND: The prevalence of hyperglycemia among HIV-infected persons who are not receiving antiretroviral therapy is unknown. We conducted a cross-sectional survey to estimate the prevalence of hyperglycemia among Chinese adults with newly diagnosed HIV/AIDS. METHODS: Two thousand and six newly diagnosed HIV/AIDS patients from 10 provinces and municipalities in China were selected during 2009 to 2010. After an overnight fast, serum samples were collected to measure glucose concentrations. Demographics and medical histories were recorded. Factors associated with the presence of diabetes were analysed by logistic regression. RESULTS: Among the 2006 patients, 75.67% were male. Median age was 40 years (range: 18–86 years). 19.99% had hyperglycemia, 9.47% had impaired fasting glucose (IFG) and 10.52% had diabetes. The prevalences of hyperglycemia, of IFG and of diabetes were 21.54%, 10.28% and 11.27% among men and 15.16%, 6.97% and 8.20% among women, respectively. The prevalence of diabetes increased with increasing age (7.00%, 13.36% and 21.21% among patients who were 18–40, 40–60, and ≥60 years of age respectively) and with decreasing CD4 count (6.74%, 8.45%, 9.69%, and 12.66% among patients with CD4 count of ≥350, 200–350, 50–200, and < 50/mm(3) respectively). The prevalence of diabetes was higher among ethnic minority patients than among the Han patients (14.37% versus 9.24%). The logistic analysis showed that older age, lower CD4 count and minority ethnicity were significantly associated with an increased risk of diabetes. CONCLUSIONS: Hyperglycemia is highly prevalent among Chinese adults with newly diagnosed HIV/AIDS. Older age, lower CD4 count and minority ethnicity are associated with increased risk of diabetes. All newly diagnosed HIV/AIDS individuals should be routinely evaluated for hyperglycemia
Identification of Blue Horizontal-Branch Stars From LAMOST DR5
We construct a new catalog of the blue horizontal-branch (BHB) stars from the
Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) DR5 dataset,
which contains 5355+81 BHB stars at high Galactic latitude
((). We combine the spectral line indices with a set of
Balmer line profile selection criteria to identify the BHB stars. During the
selection process, we use the line index of \ion{Ca}{2}\,K to exclude the
metal-rich A-type dwarfs. We obtain their atmospheric parameters by
cross-matching our BHB stars with the catalog provided by \citet{Xiang2022}.
The results show that our sample is consistent with the theoretical -log\, evolutionary tracks of the BHB stars, indicating that our method
is robust for identifying BHB stars from the LAMOST spectra. Their spatial
distribution indicates that most of our BHB stars are located in the inner halo
or the disk of the Milky Way. Combined with other BHB samples from the
literature, the BHB stars can cover a large Galactic volume, which makes it a
better probe for studying the kinematics, dynamics, and structural
characteristics of the Milky Way.Comment: accepted by ApJS.15 pages, 18 figure
In-situ synchrotron diffraction study of the phase evolution of the novel Na\u3csub\u3ex\u3c/sub\u3e(Fe\u3csub\u3e1/2\u3c/sub\u3eMn\u3csub\u3e1/2\u3c/sub\u3e)O\u3csub\u3e2\u3c/sub\u3e cathode for use in sodium-ion batteries
Abstract of a poster presentation at the 5th Australia-China Conference on Science, Technology and Eduction with the 5th Australia-China Symposium for Materials Science, at the University of Wollongong (UOW), Australia, on 21st - 23rd July 2014
Blood arsenic exposure levels of preschool children and dietary factors analysis
Objective To explore the blood arsenic exposure levels of preschool children and analyze the factors of blood arsenic. Methods By the multi-stage cluster and simple randomized method, six districts of Shanghai City was chosen and the preschool children in the selected village were asked to fill in the questionnaire and have blood sampling. Inductively coupled plasma mass spectrometry (ICP-MS) was used to detect blood arsenic, of which the data was analyzed by multiple linear regression models. Marine fish, freshwater fish, freshwater shrimp and shellfish were grouped as follows: ≤3 times per month, 1-3 times per week, and 4-6 times per week. Rice, noodles and milk were grouped as <50, 50-100, and ≥100 g/d. Results 2 263 preschool children were recruited. The range of blood arsenic was 0.12-27.94 μg/L. The median (P25, P75) were 2.26 (1.63, 3.09) μg/L. Statistical analysis showed that the more intake of rice, wheaten food, and sea fish and shrimp, the more arsenic in children’s blood (P<0.05). Whereas highter intake of freshwater fish and shrimp group showed decreased blood arsenic (P<0.05). Conclusion Most preschool children’s blood arsenic levels (92.4%, 2 091/2 263) were at normal level (<5 μg/L). There was a positive correlation between blood arsenic concentration and the intake of rice, wheaten food, and sea fish and shrimp, while negative correlation with high freshwater fish and shrimp consumption
Relaxation behavior of biaxially stretched PLA film during the heat setting stage
In this paper, the relaxation behavior of polylactic acid (PLA) film in the heat-setting stage of biaxial stretching was studied. Firstly, the polylactic acid casting films were stretched synchronously in different ratios. We found that the Machine direction (MD) and Transverse direction (TD) stress relaxation curves exhibited a separation trend with the increase in the stretching ratio, and the relaxation amplitude increased gradually. Then, the stress relaxation curves were fitted by the expansion exponential equation (KWW equation). The results showed that the coefficient used to characterize the homogeneity of stress relaxation increased with the increase in the stretching ratio, and the homogeneity in Machine direction was better than that in Transverse direction. Finally, we analyzed the evolution of rheological units and the activation energy spectrum during stress relaxation. We found that the volume of rheological units gradually decreased with the increase in the stretching ratio. The activation energy spectrum exhibited a Gaussian distribution, and the symmetry axis of distribution curves shifted to the high energy. The above results would be of great significance in further understanding the deformation mechanism of polylactic acid film during biaxial stretching and providing theoretical guidance for the preparation of high-performance BOPLA films
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