ALBERT

Description: The paper deals with the investigation of some phenomena which are essential for dynamic interaction of a wheelset or bogie with the railways track. The track is modeled as discrete–continuous system composed of rails, fastening systems and sleepers interacting with ballast by means of viscous–elastic elements. Transient and stationary problems are investigated. The stationary periodic problems are connected with wave propagation in stopping bound, passing bound and mistuning. In this paper, a review of selected problems and exemplary results of simulation and experimental investigations is given supplemented by a few results of analysis and simulation.

Description: Urban areas with rapid industrial development have major impacts on environmental soil quality. This study was carried out to determine contamination assessment of heavy metal concentration of urban soil from Klang district (Malaysia). Health risk assessment was used to determine potential health risks (carcinogenic and non-carcinogenic risks) in both adults and children. Moreover, this study was also used to identify the most significant contaminant and exposure pathway with regard to Klang urban soil. Mean bioavailability of heavy metal concentrations were found in the order of Fe (6.65 mg/kg) 〉 Zn (5.61 mg/kg) 〉 Cu (2.96 mg/kg) 〉 Co (0.22 mg/kg) 〉 Cd (0.14 mg/kg) 〉 Pb (0.11 mg/kg) 〉 Cr (0.10 mg/kg). Maximum values of Cd (0.64 mg/kg), Cu (52.14 mg/kg) and Pb (9.18 mg/kg) have exceeded some guidelines and standard values. Study findings showed that total carcinogenic risks values of Cd, Cr and Pb are more than incremental lifetime (1.0E-05). This indicates the likehood of having cancer threat for adults and children. While for total non-carcinogenic risk, none of the heavy metals (Co, Cr, Cu, Pb and Zn) showed Hazard Index values more than one indicating there is no any potential non-carcinogenic risks for adults and children in study area. From this study, Cd is the most significant contaminant as maximum concentration value has exceeded soil guidelines and potential to have carcinogenic risks to adults and children. Pathway order for both carcinogenic and non-carcinogenic risks is ingestion 〉 dermal 〉 inhalation where ingestion pathway contributed the most to potential health risks involving urban soil of Klang.

Description: The Tibetan Himalaya represents the northernmost continental unit of the Indian plate that collided with Asia in the Cenozoic. Paleomagnetic studies on the Tibetan Himalaya can help constrain the dimension and paleogeography of ‘Greater India', the Indian plate lithosphere that subducted and underthrusted below Asia after initial collision. Here, we present a paleomagnetic investigation of a Jurassic (limestones) and Lower Cretaceous (volcaniclastic sandstones) section of the Tibetan Himalaya. The limestones yielded positive fold test, showing a pre-folding origin of the isolated remanent magnetizations. Detailed paleomagnetic analyses, rock magnetic tests, end-member modeling of acquisition curves of isothermal remanent magnetization, and petrographic investigation reveal that the magnetic carrier of the Jurassic limestones is authigenic magnetite, whereas the dominant magnetic carrier of the Lower Cretaceous volcaniclastic sandstones is detrital magnetite. Our observations lead us to conclude that the Jurassic limestones record a prefolding remagnetization, whereas the Lower Cretaceous volcaniclastic sandstones retain a primary remanence. The volcaniclastic sandstones yield an Early Cretaceous paleolatitude of 55.5°S [52.5°S, 58.6°S] for the Tibetan Himalaya, suggesting it was part of the Indian plate at that time. The size of ‘Greater India' during Jurassic time cannot be estimated from these limestones. Instead, a paleolatitude of the Tibetan Himalaya of 23.8°S [21.8°S, 26.1°S] during the remagnetization process is suggested. It is likely that the remagnetization, caused by the oxidation of early diagenetic pyrite to magnetite, was induced during 103-83 Ma or 77-67 Ma. The inferred paleolatitudes at these two time intervals imply very different tectonic consequences for the Tibetan Himalaya. This article is protected by copyright. All rights reserved.

Description: Heat transfer and friction factor characteristics in a circular tube fitted with core rod at high temperature have been investigated experimentally. In the experiments, ambient air with Reynolds numbers in a range of 9,000–26,000 is passed through a circular tube with uniform wall temperature and convection and radiation heat transfer phenomena are studied. Experiments have been performed on the tube with core rod insert considering four values of uniform wall temperature. For each wall temperature considered, convection and radiation heat transfer coefficients have been determined. The experimental results show that at uniform wall temperature of 373, 473, 553 and 633 K the average share of the radiation heat transfer coefficient to the total heat transfer coefficient is 10.7, 14.6, 20.5 and 22.3 % respectively. In addition it was noted that for the mentioned temperatures, the heat transfer coefficient increased by 234, 275, 304 and 334 % respectively when using tube containing the core insert in comparison to the plain tube. It was also noted that increasing the wall temperature also resulted in increase of friction factor.

Description: In this paper, the field experiments on ground surface spectral broadband solar radiation (SR) and corresponding albedo were introduced at three man-made sites at Gobi, desert and bare loess zones during three different intensive observational periods (IOP) from 2010 to 2013 in Gansu Province, respectively. The continuous and high temporal resolution records of ground surface solar radiation are presented, including global (GR), ultraviolet (UV), visible (VIS), and near-infrared radiation (NIR). The corresponding albedos are analyzed over three typical non-vegetated underlying surfaces in arid and semi-arid and semi-humid regions of northwestern China. The preliminary investigations were carried out. The results show: the variation trends of UV, VIS and NIR are coincident with the GR, and the irradiances are gradually decreasing throughout the IOP at each site; the energy ratios of VIS/GR are all approximately 40.2%, and the ratios of NIR/GR are all approximately 54.4% at the Gobi, desert and bare loess zones; the averaged albedos of the soil for VIS are 0.231, 0.211 and 0.142, for the NIR are 0.266, 0.252 and 0.255 over the Gobi, desert and bare loess land surfaces, respectively. The energy ratios of VIS/GR and NIR/GR are not 50% as prescribed for all of the soil color classes in most of land surface models (LSMs). The observational soil albedo values for NIR are not twice to that of the VIS as predicted in some LSMs for the underlying surface at the three sites. GR albedo is determined by the energy ratios of SR/GR and SR albedos.

Description: An analysis of the recently reconstructed gridded May-September total precipitation in the Indian monsoon region for the past half millennium discloses significant variations at multidecadal timescales. Meanwhile, paleo-climate modeling outputs from NCAR CCSM4 show similar multidecadal variations in the monsoon precipitation. One of those variations at the frequency of 40–50 years per cycle is examined in this study. Major results show that this variation is a product of the processes in that the meridional gradient of the atmospheric enthalpy is strengthened by radiation loss in the high-latitude and polar region. Driven by this gradient and associated baroclinicity in the atmosphere, more heat/energy is generated in the tropical and subtropical (monsoon) region and transported poleward. This transport relaxes the meridional enthalpy gradient and, subsequently, the need for heat production in the monsoon region. The multidecadal timescale of these processes results from atmospheric circulation-radiation interactions and the inefficiency in generation of kinetic energy from the potential energy in the atmosphere to drive the eddies that transport heat poleward. This inefficiency creates a time delay between the meridional gradient of the enthalpy and the poleward transport. The monsoon precipitation variation lags that in the meridional gradient of enthalpy but leads that of the poleward heat transport. This phase relationship, and underlining chasing process by the transport of heat to the need for it driven by the meridional enthalpy gradient, sustains this multidecadal variation. This mechanism suggests that atmospheric circulation processes can contribute to multidecadal timescale variations. Interactions of these processes with other forcing, such as SST or solar irradiance anomalies, can result in resonant or suppressed variations in the Indian monsoon precipitation.

Description: The impact on the dynamics of the stratosphere of three approaches to geoengineering by Solar Radiation Management is investigated using idealized simulations of a global climate model. The approaches are geoengineering with sulfate aerosols, titania aerosols and reduction in total solar irradiance (representing mirrors placed in space). If it were possible to use stratospheric aerosols to counterbalance the surface warming produced by a quadrupling of atmospheric carbon dioxide concentrations, tropical lower stratospheric radiative heating would drive a thermal-wind response which would intensify the stratospheric polar vortices. In the Northern Hemisphere this intensification results in strong dynamical cooling of the polar stratosphere. Northern Hemisphere stratospheric sudden warming events become rare (1 or 2 in 65 years for sulfate and titania respectively). The intensification of the polar vortices results in a poleward shift of the tropospheric midlatitude jets in winter. The aerosol radiative heating enhances the tropical upwelling in the lower stratosphere, influencing the strength of the Brewer-Dobson Circulation. In contrast, solar dimming does not produce heating of the tropical lower stratosphere so there is little intensification of the polar vortex and no enhanced tropical upwelling. The dynamical response to titania aerosol is qualitatively similar to the response to sulfate.

Description: Sea ice is an active source or a sink for carbon dioxide (CO 2 ), although to what extent is not clear. Here, we analyze CO 2 dynamics within sea ice using a one-dimensional halo-thermodynamic sea ice model including gas physics and carbon biogeochemistry. The ice-ocean fluxes, and vertical transport, of total dissolved inorganic carbon (DIC) and total alkalinity (TA) are represented using fluid transport equations. Carbonate chemistry, the consumption and release of CO 2 by primary production and respiration, the precipitation and dissolution of ikaite (CaCO 3 •6H 2 O) and ice-air CO 2 fluxes, are also included. The model is evaluated using observations from a 6-month field study at Point Barrow, Alaska and an ice-tank experiment. At Barrow, results show that the DIC budget is mainly driven by physical processes, wheras brine-air CO 2 fluxes, ikaite formation, and net primary production, are secondary factors. In terms of ice-atmosphere CO 2 exchanges, sea ice is a net CO 2 source and sink in winter and summer, respectively. The formulation of the ice-atmosphere CO 2 flux impacts the simulated near-surface CO 2 partial pressure ( p CO 2 ), but not the DIC budget. Because the simulated ice-atmosphere CO 2 fluxes are limited by DIC stocks, and therefore 〈 2 mmol m -2 day -1 , we argue that the observed much larger CO 2 fluxes from eddy covariance retrievals cannot be explained by a sea ice direct source and must involve other processes or other sources of CO 2 . Finally, the simulations suggest that near surface TA/DIC ratios of ~2, sometimes used as an indicator of calcification, would rather suggest outgassing. This article is protected by copyright. All rights reserved.