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Sharp-crested weirs are the simplest form of over-flow spillway that commonly used to determine the flow rate in hydraulic
laboratories, industry and irrigation systems, where highly accurate discharge measurements are needed. In this study, the
experimental upper and lower nappe profiles in rectangular sharp-crested weirs are fitted by quadratic and cubic equations,
respectively. In addition, free-vortex theory is used to simulate flow over this kind of weirs and determine discharge coefficient.
Physical models of sharp-crested weirs with various widths and heights were considered. The proposed method agrees well with
the experimental observations. Also, the experimental data indicate that the suggested equation presents reasonable results
for the range of 0 < h/P < 9. 相似文献
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Mahin Karami Manouchehr Amini Majid Afyuni Amir Hossin Khoshgoftarmanesh Armin Keller Ali Abdi 《Archives of Agronomy and Soil Science》2013,59(3):437-456
Mass flux assessment can provide information that is essential for a sustainable management of elements in agricultural soils. In this article, we present an assessment of regional-scale averages of zinc (Zn) fluxes into agricultural soils and crops of central Iran for the period 1997–2011, using available databases such as regional agricultural statistics. The basic units of the balances were 15 townships of the provinces Qom, Isfahan and Fars. Averaged over the entire study region, the net Zn input into arable soil resulting from all fertilizer inputs – Zn removal with harvested crops was 1515 g ha?1 yr?1 across the entire region, with a range of 438–3009 g ha?1 yr?1 among townships. Estimated average Zn inputs with manure, mineral fertilizers, sewage sludge and compost were 1254, 531, 19 and 7 g ha?1 yr?1, respectively. The input-to-output ratio of these fluxes ranged from 1.8 to 12.9 among townships and averaged 6.1 for the entire study area. Considering that outputs other than with crop harvests are minor, Zn stocks are rapidly building up in the soils of the study region. Uncertainties in the manure and crop removal data were the main sources of estimation uncertainty in this study. 相似文献
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Repurposing Ionophores as novel antimicrobial agents for the treatment of bovine mastitis caused by Gram‐positive pathogens 下载免费PDF全文
Elizabeth E. Hickey Hui San Wong Manouchehr Khazandi Abiodun D. Ogunniyi Kiro R. Petrovski Sanjay Garg Stephen W. Page Ryan O'Handley Darren J. Trott 《Journal of veterinary pharmacology and therapeutics》2018,41(5):746-754
Increasing reports of multidrug‐resistant bacterial infections in animals has created a need for novel antimicrobial agents that do not promote cross‐resistance to critically important antimicrobial classes used in human medicine. In response to the recent emergence of antimicrobial resistance in several bovine mastitis pathogens, in vitro antimicrobial susceptibility was determined for four polyether ionophores (lasalocid, monensin, narasin and salinomycin) against Staphylococcus spp. and Streptococcus spp. isolated from clinical cases. In addition, erythrocyte haemolysis and WST ‐1 cell proliferation assays were used to assess in vitro mammalian cell cytotoxicity and biofilm susceptibility testing was performed using the minimum biofilm eradication concentration (MBEC ?) biofilm assay. Lasalocid, monensin, narasin and salinomycin exhibited bacteriostatic antimicrobial activity against all pathogens tested, including methicillin‐resistant staphylococci, with MIC 90 values <16 μg/ml. Narasin and monensin displayed the least toxicity against mammalian cell lines and all compounds significantly reduced viable cell numbers in a Staphylococcus aureus biofilm. Based on in vitro characterization, all four ionophores offer potentially novel treatments against bovine mastitis but in vivo studies will be essential to determine whether acceptable safety and efficacy is present following intramammary administration. 相似文献
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Sharifi Arezoo Gorji Manuchehr Asadi Hossein Pourbabaee Ahmad Ali 《Paddy and Water Environment》2014,12(1):139-145
Paddy and Water Environment - The aim of this study was to evaluate the impacts of land leveling on some of soil properties. Land leveling as an effective strategy for paddy land management is one... 相似文献
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Mohmoud Bayat Timo Pukkala Manouchehr Namiranian Mahmoud Zobeiri 《European Journal of Forest Research》2013,132(5-6):851-864
Hyrcania is a productive region near the southern coast of Caspian Sea. Her forests are mostly uneven-aged beach-dominated hardwood mixtures. There is increasing willingness to treat these forests without clear-felling, following the ideas of continuous cover management. However, lack of growth and yield models have delayed this endeavor, and no instructions for uneven-aged management have been issued so far. This study developed a set of models that enable the simulation of stand development in alternative management schedules. The models were used to optimize stand structure and the way in which various initial stands should be converted to the optimal uneven-aged structure. The model set consists of individual-tree diameter increment model, individual-tree height model, survival model, and a model for ingrowth. The models indicate that the sustainable yield of the forests ranges from 2.2 to 7 m3 ha?1 a?1 in uneven-aged management, depending on species composition. Better ingrowth would substantially enhance productivity. The optimal stand structure for maximum sustained yield has a wide descending diameter distribution, the largest trees of the post-cutting stand being 80–100 cm in dbh. If cuttings are conducted at 30- or 40-year intervals, they should remove 20–40 largest trees per hectare. Despite moderate growth rate, uneven-aged management produces high incomes, 850–1,000 UDS ha?1a?1, because the timber assortments that are obtained from the removed large trees have very high selling prices. Optimal conversion to uneven-aged structure showed that the steady-state stand structure depends on initial stand condition and discount rate when the length of the conversion period is fixed. Discount rates higher than 1 % lead to reduced wood production, heavy cuttings, and low basal areas of the steady-state forest. 相似文献
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Moisture management behavior is a vital factor in evaluating thermal and physiological comfort of functional textiles. This
research work studies functional 3 dimensional (3D) warp knitted spacer fabrics containing high-wicking materials characterized
by their profiled cross section. These spacer fabrics can be used for protective vest to absorb a user’s sweat, to reduce
the humidity and improve user’s thermal comfort. For this reason, different 3D warp knitted spacer fabrics were produced with
functional fiber yarns in the back layer of the fabric (close to the body) and polyester in the front and middle layers (outer
surface). Comfort properties such as air and water vapor permeability and wicking and other moisture management properties
(MMP) of different fabric samples were measured. It is demonstrated that by using profiled fibers such as Coolmax fiber, moisture
management properties of spacer fabrics can be improved, enabling them to be use as a snug-fitting shirt worn under protective
vests with improved comfort. 相似文献