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On the relation between size and distance travelled for wind-driven sand grains — Results and discussion of a pilot experiment using coloured sand
Published in B. Mutlu Sumer, A. Müller, Mechanics of Sediment Transport, 2020
Ole Barndorff-Nielsen, Jens Ledet Jensen, Michael SØrensen
The spraying procedure has two disadvantages, the first being that the air stream from the spray may change the structure of the surface and the second being that the depth to which the spray penetrates differs from section to section. The sections were located successively, at 12.5 cm downwind of the original crest of coloured sand and then every 10 cm downwind until 122.5 cm? at 102.5 cm and 122.5 cm no glass tray samples were preserved. The locations for which both the central part and the glass tray parts were preserved are numbered 1 to 10, 1 being at 12.5 cm downwind and 10 at 112.5 cm downwind. The reason not to take more sand samples further downstream was that we thought (wrongly, as it turned out) that the amount of coloured grains would be too small for a reliable estimation.
Surface Treatments
Published in Thomas E. Carleson, Nathan A. Chipman, Chien M. Wai, Separation Techniques in Nuclear Waste Management, 2017
High-pressure fluids are commonly used to remove contamination from surfaces. Several fluids have been used, with the majority of systems using high-pressure water or Freon.9 Water sprays operating at pressures up to 10,000 psi are used to remove loose contamination. Sprays operating at pressures over 10,000 psi have demonstrated removal of not only loose contamination, but also base metal. High-pressure water can be used to decontaminate large and small components with simple and irregular geometries. High-pressure water decontamination can be enhanced by the addition of abrasives or chemical agents. Disadvantages of high-pressure water sprays include possible redistribution of contamination, possible production of large volumes of liquid radioactive waste, and possible formation of airborne contamination.
Layer-by-Layer Assembly: A Novel Flame-Retardant Solution to Polymeric Materials
Published in Yuan Hu, Xin Wang, Flame Retardant Polymeric Materials, 2019
On the other hand, LbL is experiencing some limitations, mainly referable to the transfer of this technology from lab-scale to industrial-scale: in this context, the spray LbL method could be applied to roll-to-roll industrial plants, as already demonstrated at a pilot-scale (Chang et al. 2014). Undoubtedly, spray coating is fast and reduces material waste; furthermore, it eliminates the risk of solution/suspension contamination that may take place through repetitive dipping into the solution/suspension baths.
Assessment of risks to listed species from the use of atrazine in the USA: a perspective
Published in Journal of Toxicology and Environmental Health, Part B, 2021
Philip N Smith, Kevin L Armbrust, Richard A. Brain, Wenlin Chen, Nika Galic, Lula Ghebremichael, Jeffrey M Giddings, Mark L Hanson, Jonathan Maul, Glen Van Der Kraak, Keith R Solomon
Non-target organisms can be exposed directly to pesticides during application or inadvertently via spray drift, through exposure to treated soil, or water contaminated from precipitation-induced runoff from fields treated with the chemical. When chemicals are transported from the site of application to an aquatic system, the levels found in water will be a function of a series of factors related to the both the environment as well as the properties of the chemical. Such factors include, but are not limited to, the rate of application, how frequently the runoff events occur, the magnitude of the runoff events, the timing of the runoff events relative to the time of application and the persistence of the chemical in soil and water, properties of the soil and adsorption to the constituents of the soil. Exposure-concentrations can be measured directly through analyzing water, soil, and sediment samples for chemical residues; however, for residues in water, these methods are plagued by questions of whether the highest concentrations were truly measured and if peak concentrations were missed as samples were not taken at the instant of peak concentrations in the water-body (USEPA 2016). Additionally, the costs of measuring concentrations can be prohibitively expensive for temporal sampling at multiple sites. However, a well-designed monitoring investigation with appropriate sampling intervals and reliable analysis backed up by a rigorous quality assurance plan to ensure accuracy of the data undoubtedly will yield the most useful information on exposure for purposes of risk assessment.
Development of structural deterioration models for flexible pavement using traffic speed deflectometer data
Published in International Journal of Pavement Engineering, 2021
Sittampalam Manoharan, Gary Chai, Sanaul Chowdhury
There are several factors influencing structural performance in flexible pavements, the main factors are traffic volume, percentage of heavy vehicles, seal age, seal width, seal type, pavement age, pavement thickness, subgrade type, lower soil moisture content, curvature and subgrade strength. Traffic volume and percentage of heavy vehicles are collected annually using vehicle counters and with the collected data stored on a centralised database. Traffic volume is reported as Annual Average Daily Traffic (AADT) and the percentage of heavy vehicles is reported as a percentage of AADT. The inventory data including seal age (years), surface type (spray seal or asphalt), pavement age (years) and thickness (mm) are obtained from as constructed drawings and pavement studies are stored on a TMR asset management database. Subgrade type is divided into four types based on subgrade material properties (reactive or non-reactive) in combination with annual rainfall (less than 800 mm or exceeding 800 mm). Based on these types, roads within Qld’s network have been assigned to the appropriate subgrade type and this information is available on TMR’s asset management database (WR, WNR, DR and DNR). Lower soil moisture represents the percentage of available water content in soils between 10 and 100 cm into the soil profile. A soil layers maximum storage is calculated using the thickness and the relative soil water storage capacity of the material. The properties of the various soil types that control storage of water are available from the Australian Soil Resources Information System. The data is collected daily and is available on Australian Government Bureau of Meteorology website as a percentage (Australian Landscape Water Balance 2019). The moisture content data is collected in 5 km grids and it will have impact on independent variable, if the pavement sections are 5 km apart (Australian Landscape Water Balance 2019). Due to changes in soil type/zones over the length of pavement section seasonal variations on pavement is significant. For instance, in Western Queensland the environment typically undergoes continuous wetting and drying cycles resulting in swelling and shrinkage of expansive materials causing premature pavement failure (Department of Transport and Main Roads 2019). Seal age is a useful indicator regarding the condition of a seal and its ability to prevent the ingress of water into the pavement. Surface type can either be spray seal or asphalt. Spray seals whilst having a substantially lower cost and seal life, require ongoing maintenance due to minor surface cracking that can be attributed to the bitumen hardening due to oxidation. This can result in a weakening of the underlying pavement as it becomes more permeable. Pavement age plays a pivotal role in the prediction of a pavement deterioration as observed by pavement practitioners. This factor can account for declines in serviceability for many roads as it is affected by cumulative traffic loads and changes in environmental conditions (George et al.1989 ).