547 research outputs found

    Estimating Vehicle Miles of Travel on Low Functional Classes of Roadways

    Get PDF
    In this research, new methods to estimate vehicle miles traveled (VMT) for lower functional classes of roadways are introduced. The methods are based on the inherent correlation between VMT and roadway densities in each roadway class. This research found that the relationship between VMTs of different functional classes of roadways has to do with roadway typological structures according to functional classifications. To begin with, the analytical relationship between local VMT and collector road VMT was derived by assuming a grid network. The purpose was to find key relevant terms (basically roadway densities) in the relationship, which were used to define the format of regression equations. Next, the author proposed two types of regression models, one using density ratios as explanatory variables and the other using logarithmic value of roadway densities. Several simulation networks were set up to verify those proposed models using community road patterns categorized according to three different measures. The author found that the proposed models worked well for medium and high connectivity networks, but they were inadequate for simulating low connectivity networks. Moreover, the equation using logarithmic terms provided a better result in every numerical test. Next, the author verified the proposed regression equations in real situations. The results showed that the proposed regression models work very well in estimating urban local VMT of Minneapolis (grid networks). However, the relative error was much bigger in estimating local VMT of Bryan/College Station (non-grid networks). Finally, the author introduced a practical application procedure and also discussed the possible sources of errors in this study. This research introduces a potentially more efficient method (logarithm) for estimating VMT for lower functional classes of roadways

    Chemical Carcinogenesis and Nasopharyngeal Carcinoma

    Get PDF

    In Situ Experimental Study of the Friction of Sea Ice and Steel on Sea Ice

    Get PDF
    The kinetic coefficient of friction ÎŒk was measured for sea ice, stainless steel, and coated steel sliding on a natural sea ice cover. The effects of normal stress (3.10–8.11 kPa), ice columnar grain orientation (vertical and parallel to the sliding direction), sliding velocity (0.02–2.97 m·s–1), and contact material were investigated. Air temperature was higher than −5.0 °C for the test duration. The results showed a decline of ÎŒk with increasing normal stress with ÎŒk independent of ice grain orientation. The ÎŒk of different materials varied, partly due to distinct surface roughnesses, but all cases showed a similar increasing trend with increasing velocity because of the viscous resistance of melt-water film. The velocity dependence of ÎŒk was quantified using the rate- and state- dependent model, and ÎŒk was found to increase logarithmically with increasing velocity. In addition, ÎŒk obtained at higher air temperatures was greater than at lower temperatures. The stick-slip phenomenon was observed at a relatively high velocity compared with previous studies, which was partly due to the low-stiffness device used in the field. Based on the experimental data, the calculation of physical models can be compared.Peer reviewe

    The Milky Way's rotation curve out to 100 kpc and its constraint on the Galactic mass distribution

    Full text link
    The rotation curve (RC) of the Milky Way out to ∌\sim 100 kpc has been constructed using ∌\sim 16,000 primary red clump giants (PRCGs) in the outer disk selected from the LSS-GAC and the SDSS-III/APOGEE survey, combined with ∌\sim 5700 halo K giants (HKGs) selected from the SDSS/SEGUE survey. To derive the RC, the PRCG sample of the warm disc population and the HKG sample of halo stellar population are respectively analyzed using a kinematical model allowing for the asymmetric drift corrections and re-analyzed using the spherical Jeans equation along with measurements of the anisotropic parameter ÎČ\beta currently available. The typical uncertainties of RC derived from the PRCG and HKG samples are respectively 5-7 km/s and several tens km/s. We determine a circular velocity at the solar position, Vc(R0)V_c (R_0) = 240 ±\pm 6 km/s and an azimuthal peculiar speed of the Sun, V⊙V_{\odot} = 12.1 ±\pm 7.6 km/s, both in good agreement with the previous determinations. The newly constructed RC has a generally flat value of 240 km/s within a Galactocentric distance rr of 25 kpc and then decreases steadily to 150 km/s at rr ∌\sim 100 kpc. On top of this overall trend, the RC exhibits two prominent localized dips, one at rr ∌\sim 11 kpc and another at rr ∌\sim 19 kpc. From the newly constructed RC, combined with other constraints, we have built a parametrized mass model for the Galaxy, yielding a virial mass of the Milky Way's dark matter halo of 0.90−0.08+0.07×10120.90^{+0.07}_{-0.08} \times 10^{12} M⊙{\rm M}_{\odot} and a local dark matter density, ρ⊙,dm=0.32−0.02+0.02\rho_{\rm \odot, dm} = 0.32^{+0.02}_{-0.02} GeV cm−3^{-3}.Comment: MNRAS accepted, 18 pages, 15 figures, 4 table

    Mass and Heat Balance of a Lake Ice Cover in the Central Asian Arid Climate Zone

    Get PDF
    To improve the understanding of the seasonal evolution of the mass and heat budget of ice-covered lakes in the cold and arid climate zone, in-situ observations were collected during two winters (2016–2017 and 2017–2018) in Lake Wuliangsuhai, Inner Mongolia, China. The mean snow thickness was 5.2 and 1.6 cm in these winters, due to low winter precipitation. The mean ice thickness was 50.9 and 36.1 cm, and the ice growth rate was 3.6 and 2.1 mm day−1 at the lower boundary of ice. Analyses of mass and heat balance data from two winters revealed that the surface heat budget was governed by solar radiation and terrestrial radiation. The net heat flux loss of the ice was 9–22 W m−2, affected by the snow and ice thickness. Compared to boreal lakes, Lake Wuliangsuhai received more solar radiation and heat flux from the water. The ice temperature had a strong diurnal variation, which was produced by the diurnal cycles of solar radiation, and air and water temperatures. These results expand our knowledge of the evolution of mass and heat balance in temperate lakes of mid-latitude arid areas

    Solar radiation transfer for an ice-covered lake in the central Asian arid climate zone

    Get PDF
    Spectral albedo and light transmittance through snow, ice, and water were measured in Lake Wuliangsuhai (40 degrees 36 '-41 degrees 30 ' N, 108 degrees 43 '-108 degrees 70 ' E), Inner Mongolia, China, during winter 2016. Data on the weather, structure of lake ice, and geochemistry of water were also collected during the 60-day field program. The study lake is shallow (mean depth 1.0-1.5 m) with a large wetland area. Compared with polar lakes, solar elevation is higher, snow accumulation is much lower, and the ice has more sediment. The ice was all congelation ice with a mean thickness of 36.6 cm, corresponding to a mean air temperature of -9.6 degrees C. The mean daily broadband albedo and photosynthetically active radiation (PAR) band transmittance were 0.54 and 0.08 (bare ice), 0.74 and 0.04 (new snow), and 0.30 and 0.12 (melting period), respectively. The level of light allowed photosynthesis to occur to the bottom of the lake. The ice acted as a grey filter for the sunlight with a mean attenuation coefficient of 2.1 m(-1). These results expand our knowledge of the evolution of light transfer through ice and snow cover and its role in the ecology of lakes in temperate and arid areas.Peer reviewe

    Ganoderma: A Cancer Immunotherapy Review

    Get PDF
    Ganoderma is a significant source of natural fungal medicines and has been used for the treatment of various diseases for many years. However, the use of Ganoderma in cancer immunotherapy is poorly elucidated. In this study, we have analyzed 2,398 English-language papers and 6,968 Chinese-language papers published between 1987 and 2017 by using bibliometrics. A steady growth in the number of publications was observed before 2004, followed by an exponential increase between 2004 and 2017. The most common category for publications about Ganoderma was “Pharmacology & Pharmacy,” in which immunomodulation (25.60%) and cancer treatment (21.40%) were the most popular subcategories. Moreover, we have provided an overview of the bioactive components and combinatorial immunomodulatory effects for the use of Ganoderma in the treatment of cancer, including the major pathways of immune cells. Immunomodulatory protein and polysaccharides are the key bioactive factors responsible for cancer immunotherapy, and the NF-ÎșB and MAPK pathways are the most comprehensively investigated major pathways. Our results indicate that Ganoderma has a broad-spectrum application for the treatment of cancer through the regulation of the immune system. This review provides guidance for future research into the role of Ganoderma in cancer immunotherapy
    • 

    corecore