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排序方式: 共有1681条查询结果,搜索用时 62 毫秒
391.
Markus Stumm Michael Entezami Karsten Haug Cornelia Blank Max Wüstemann Bernt Schulze Gisela Raabe-Meyer Maja Hempel Markus Schelling Eva Ostermayer Sabine Langer-Freitag Tilo Burkhardt Roland Zimmermann Tina Schleicher Bernd Weil Ulrike Schöck Patricia Smerdka Sebastian Grömminger Yadhu Kumar Wera Hofmann 《黑龙江环境通报》2014,34(2):185-191
392.
393.
Abhishek Sanskrityayn Vijay P. Singh Vinod Kumar Bharati Naveen Kumar 《Environmental Fluid Mechanics》2018,18(3):739-757
In the present study analytical solutions of a two-dimensional advection–dispersion equation (ADE) with spatially and temporally dependent longitudinal and lateral components of the dispersion coefficient and velocity are obtained using Green’s Function Method (GFM). These solutions describe solute transport in infinite horizontal groundwater flow, assimilating the spatio-temporal dependence of transport properties, dependence of dispersion coefficient on velocity, and the particulate heterogeneity of the aquifer. The solution is obtained in the general form of temporal dependence and the source term, from which solutions for instantaneous and continuous point sources are derived. The spatial dependence of groundwater velocity is considered non-homogeneous linear, whereas the dispersion coefficient is considered proportional to the square of spatial dependence of velocity. An asymptotically increasing temporal function is considered to illustrate the proposed solutions. The solutions are validated with the existing solutions derived from the proposed solutions in three special cases. The effect of spatially/temporally dependent heterogeneity on the solute transport is also demonstrated. To use the GFM, the ADE with spatio-temporally dependent coefficients is reduced to a dispersion equation with constant coefficients in terms of new position variables introduced through properly developed coordinate transformation equations. Also, a new time variable is introduced through a known transformation. 相似文献
394.
Nain Anil Lohchab Rajesh Kumar Singh Kulbir Kumari Mikhlesh Saini Jitender Kumar 《Journal of Material Cycles and Waste Management》2021,23(6):2192-2207
Journal of Material Cycles and Waste Management - Recirculation of the leachate using bioreactor technology for in-situ treatment of leachate is an efficient method for reducing the contaminants... 相似文献
395.
Jain Piyush Kumar Lanjewar Atul Rana Kunj Bihari Meena Makkhan Lal 《Environmental science and pollution research international》2021,28(4):4019-4055
Environmental Science and Pollution Research - Solar power is one of the main sources of renewable energy which helps for protecting the environmental and reducing pollution. Technologies and... 相似文献
396.
Rahul Jain Makkhan Lal Meena Manoj Kumar Sain Govind Sharan Dangayach 《International journal of occupational safety and ergonomics》2019,25(2):194-199
Purpose. In ergonomics and human factors investigations, pulling force (PF) estimation has usually been achieved using various types of biomechanical models, and independent approximation of PF was done with the help of upper extremity joints. Recently, multiple regression methods have gained importance for task-relevant inputs in predicting PF. Artificial neural networks (ANNs) also play a vital role in fitting the data; however, their use in work-related biomechanics and ergonomics is inadequate. Therefore, the current research aimed to accomplish comparative investigation of ANN and regression models by assessing their capacity to predict PF values. Methods. Multipositional PF data were acquired from 200 subjects at three different handle heights and body locations. ANN and regression models were formed using a random sample of three subsets (75% training, 15% selection, 10% validation) for proving the outcomes. Results. The comparison of ANN and regression models shows that the predictions of ANN models had a profoundly explained variance and lower root mean square difference values for the PF data at three handle heights. Conclusions. These outcomes advise that ANNs offer a precise and robust substitute for regression methods, and should be considered a useful method in biomechanics and ergonomics task assessments. 相似文献
397.
Global scale drivers such as international markets for shrimp can trigger large changes at local and regional scales. But there is also a poorly appreciated reverse process, operating from the bottom up, with potential for triggering changes at higher scales. Thus, effects of drivers can be seen as a two-way process in which global drivers and local and regional drivers can potentially impact each other. Here, we argue that not only can global drivers impact the sustainability of local and regional social-ecological systems, but sustainability at higher scales can also be impacted by changes at the scale of local and regional social-ecological systems. Using Chilika, a large lagoon on the Bay of Bengal, Odisha State in India as a case, we show that traditional small-scale capture fisheries supporting 150 fisher villages with some 400,000 people were marginalized by aquaculture development for tiger prawn and by state-driven hydrological interventions, with impacts on the ecology of the lagoon. These changes, in turn, contribute to global poverty and food insecurity, making it difficult for India to meet international targets such as millennium development goals. The marginalized fisherfolk become part of environmental justice and other social movements. With large parts of the lagoon converted into a virtual monoculture for the production of tiger prawn, changes in Chilika (a Ramsar site) contribute to wetland habitat loss at the global scale, and biodiversity losses, possibly including IUCN red-listed species. 相似文献
398.
Ajay Kumar Kaviti Akhilesh Yadav Amit Shukla 《International Journal of Green Energy》2019,16(6):442-449
Developing a compact, simple, and productive solar still is a main challenge. This paper describes a simple modification of the solar still that significantly enhances its productivity. A laboratory scale of modified single effect double slope glass solar still with the opaque triangular north wall has been developed and tested for enhancement of productivity in sunny days of the summer season in the month of April. The experiments on still have been carried out under three levels of water depths from 1 to 3 cm and compared it with the performance of conventional still of double slope single effect solar still of the same size. It is clear from the observations that opaque type still gave maximum distillate of 1793 ml at 1 cm depth of water while conventional still could produce only 1519 ml for the same depth of water. Also, for 2 and 3 cm depth of water, the opaque type still found to be more productive than conventional double slope solar still. As the former produced 1532 and 1464 ml while the latter produced 1328 and 1235 ml, for 2 and 3 cm depth of water, respectively. 相似文献
399.
Ramesh Chand Kasana Nav Raten Panwar Ramesh Kumar Kaul Praveen Kumar 《Environmental Chemistry Letters》2017,15(2):233-240
Copper nanoparticles have improved properties compared to the bulk copper material. Copper nanoparticles indeed find applications in gas sensors, heat transfer fluids, catalysis, solar energy and batteries. Antibacterial and antifungal activities of copper nanoparticles find applications in the agriculture and healthcare sectors. Nonetheless, careless use of copper nanoparticles may cause environmental pollution and health effects. Here we review the biosynthesis of copper nanoparticles using plant materials, named phytosynthesis, and micro-organisms. We also discuss the effect of copper nanoparticles on crops and pathogenic micro-organisms. Copper nanoparticles varying in sizes from 5 to 295 nm have been synthesized using leaf extracts and latex from plants, and using bacteria and fungi. Biosynthesized copper nanoparticles show good antimicrobial activity inhibiting the growth of pathogenic bacteria and pathogenic fungi. Copper nanoparticles enhance the germination and growth of some plants at lower concentrations, whereas high concentrations result in retarded growth. 相似文献
400.
We propose a productivity index for undesirable outputs such as carbon dioxide (CO2) and sulfur dioxide (SO2) emissions and measure it using data from 51 developed and developing countries over the period 1971–2000. About half of the countries exhibit the productivity growth. The changes in the productivity index are linked with their respective per capita income using a semi-parametric model. Our results show technological catch up of low-income countries. However, overall productivities both of SO2 and CO2 show somewhat different results. 相似文献