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1.
Surface distortions in the form of wrinkles are often observed in sheet metals during stamping and other forming operations. Because of the trend in recent years towards thinner, higher-strength sheet metals, wrinkling is increasingly becoming a more common and troublesome mode of failure in sheet metal forming. The prediction and prevention of wrinkling during a sheet forming process are important issues for the design of part geometry and processing parameters. This paper treats the phenomenon of flange wrinkling as a bifurcated solution of the equations governing the deep drawing problem when the flat position of the flange becomes unstable. Hill’s bifurcation criterion is used to predict the onset of flange wrinkling in circular and square cup drawing. In particular, the maximum cup height that can be drawn without the onset of flange wrinkling is predicted for the given set of process parameters. A parametric study of the maximum cup height is also carried out with respect to various geometric, material and process parameters. Finite element formulation, based on the updated Lagrangian approach, is employed for the analysis. The incremental logarithmic strain measure, which allows the use of a large incremental deformation, is used. The stresses are updated in a material frame. The material is assumed to be elastic–plastic, strain hardening, yielding according to an anisotropic yield criterion of Barlat et al. (2005) [23] (named as Yld2004-18p). Isotropic power law hardening is assumed. Inertia forces are neglected due to small accelerations. Modified Newton–Raphson iterative technique is used to solve the nonlinear incremental equations. 相似文献
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Karen L. Stals Matthew Wakeling Júlia Baptista Richard Caswell Andrew Parrish Julia Rankin Carolyn Tysoe Garan Jones Adam C. Gunning Hana Lango Allen Lisa Bradley Angela F. Brady Helena Carley Jenny Carmichael Bruce Castle Deirdre Cilliers Helen Cox Charu Deshpande Abhijit Dixit Jacqueline Eason Frances Elmslie Andrew E. Fry Alan Fryer Muriel Holder Tessa Homfray Emma Kivuva Victoria McKay Ruth Newbury-Ecob Michael Parker Ravi Savarirayan Claire Searle Nora Shannon Deborah Shears Sarah Smithson Ellen Thomas Peter D. Turnpenny Vinod Varghese Pradeep Vasudevan Emma Wakeling Emma L. Baple Sian Ellard 《黑龙江环境通报》2018,38(1):33-43
针对传统教与学算法在解决复杂多峰函数优化问题时,具有局部最优且搜索开发能力较差的缺点,提出了一种改进的多学习教与学优化算法,新算法为学员的每一维加入不同的教学因子,设计了基于学员均值比较的教师选择策略和向教师及学员学习的多学习策略。基于多个单峰和多峰函数的仿真结果表明,新算法跟传统的、改进的教与学算法相比,在稳定性、寻优精度和收敛速度方面更具优势。 相似文献
3.
Dixit Rewati Gupta Anirudh Jordan Norbert Zhou Shengqiang Schild Dieter Weiss Stephan Guillon Emmanuel Jain Rohan Lens Piet 《Environmental science and pollution research international》2021,28(30):40264-40274
Environmental Science and Pollution Research - Bioreduction of selenium oxyanions to elemental selenium is ubiquitous; elucidating the properties of this biogenic elemental selenium (BioSe) is thus... 相似文献
4.
Various aquatic plant species are known to accumulate heavy metals through the process of bioaccumulation. World’s most troublesome
aquatic weed water hyacinth (Eichhornia crassipes) has been studied for its tendency to bio-accumulate and bio-magnify the heavy metal contaminants present in water bodies.
The chemical investigation of plant parts has shown that it accumulates heavy metals like lead (Pb), chromium (Cr), zinc (Zn),
manganese (Mn) and copper (Cu) to a large extent. Of all the heavy metals studied Pb, Zn and Mn tend to show greater affinity
towards bioaccumulation. The higher concentration of metal in the aquatic weed signifies the biomagnification that lead to
filtration of metallic ions from polluted water. The concept that E. crassipes can be used as a natural aquatic treatment system in the uptake of heavy metals is explored. 相似文献
5.
Water is key element in human life. All forms of life upon the earth depend upon water for their mere existence. Life & water
may be aptly said to be two facets of the same coin. Most of the water bodies are getting polluted due to domestic waste,
sewage, industrial waste and agricultural effluent. The present study is designed to ascertain the effectiveness of artificial
aeration cum Ozonizer unit installed at Lower Lake, Bhopal for assessment of water quality. Various physico- chemical parameters
like pH, Dissolved oxygen, Biochemical Oxygen demand, Chemical oxygen demand, nitrate, phosphate and bacteriological status
were studied to assess the extent of deterioration in water quality of Lower lake and at the same time to assess the performance
of the dual aeration system in improvement of water quality. 相似文献
6.
Water quality improvement through macrophytes—a review 总被引:5,自引:0,他引:5
Increasing urbanization, industrialization and over population is leading to the degradation of the environment. The main hazardous contents of the water pollution are heavy metals etc. Water bodies are the main targets for disposing the pollutants directly or indirectly. They are again at the receiving end as the storm water, residential and commercial waste is disposed into it. The prevailing purification technologies used to remove the contaminants are too costly and sometimes non-eco friendly also. Therefore, the research is oriented towards low cost and eco friendly technology for water purification, which will be beneficial for community. The present paper is a comprehensive review of approximately 38 literature sources. The paper discusses the potential of different aquatic plants (macrophytes) in purifying water and wastewater. Experimental work was developed to test the hypothesis that nutrient enrichment enhances metal tolerance of relative macrophyte. 相似文献
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8.
Structural insights on bioremediation of polycyclic aromatic hydrocarbons using microalgae: a modelling-based computational study 总被引:1,自引:0,他引:1
Pandian SureshKumar Jibu Thomas Vasudevan Poornima 《Environmental monitoring and assessment》2018,190(2):92
Research on bioremediation of polycyclic aromatic hydrocarbons (PAHs) has established that several remediating microbial species are capable of degrading only low molecular weight (LMW)-PAHs, whereas high molecular weight (HMW)-PAHs are hardly degradable. In the present study, the efficiency of degradation of both LMW and HMW-PAHs by cytochrome P450 monooxygenase (CYP) of microalgae was studied. CYP have a key role in the detoxification of xenobiotics. So far, the structure of CYP in microalgae is not predicted; the protein structure was constructed by molecular modelling in the current study using the available template of microalgal CYP. Modelled microalgae 3D structures were docked against 38 different PAH compounds, and the information regarding the interaction between protein and PAHs viz. binding sites along with mode of interactions was investigated. We report that CYP from the microalgae Haematococcus pluvialis and Parachlorella kessleri was found to possess broad oxidising capability towards both LMW and HMW-PAHs. P. kessleri showed a least value with extra precision glide score of ? 10.23 and glide energy of ? 23.48 kcal/mol. PAHs bind to CYP active sites at Lys 69, Trp 96, Gln 397 and Arg 398 through intermolecular hydrogen bonding. Also, study revealed that PAHs interacted with CYP active sites through intermolecular hydrogen bonding, hydrophobic bonding, π–π interactions and van der waals interactions. Thus, structural elucidation study confirms that microalgae Parachlorella kessleri have the capacity to remediate HMW more efficiently than other microorganisms. Our results provide a framework in understanding the structure and the possible binding sites of CYP protein for degradation of PAH and that could be a screening tool in identifying the phycoremediation potential. 相似文献
9.
The present study evaluated the potential of white-rot fungal strain Coriolus versicolor to decolorize five structurally di erent dyes
in sequential batch reactors under optimized conditions. The experiments were run continuously for seven cycles of 8 d each. High
decolorizing activity was observed even during the repeated reuse of the fungus, especially when the old medium was replaced with
fresh medium after every cycle. Biodegradation was the dominating factor as the fungus was able to produce the enzyme laccase mainly,
to mineralize synthetic dyes. The nutrients and composition of the medium played important roles in sustaining the decolorisation
potential of the fungus. Corncob was found be an easy and cheap substitute for carbon source for the fungus. Glucose consumption by
the fungus was in accordance to its decolorisation activity and chemical oxygen demand (COD) reduction. 相似文献
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