خيارات البحث
النتائج 1321 - 1330 من 3,243
Impact of Soil and Water Conservation Measures on Runoff and Sediment Environment in Wei River Basin
2015
Wang Hongjie | Gao Jianen | Wang Hong | Liu Li
The impact of the soil and water conservation measures in the process of river runoff and sediment discharge has caused wide attention. The Wei River, which has a serious water shortage and a high sediment concentration, was selected as the research watershed. Based on the measured data of rainfall, runoff and sediment, the statistical methods of wavelet analysis, Mann-Kendall test, and double cumulative curve were used to analyse the impact of soil and water conservation on runoff and sediment environment in Wei River Basin. The results showed that the river transported sediment increased during 1930s-1970s, and the average increasing rate was about 0.035×108 t/a. And the river transported sediment decreased after 1970s and the average decreasing rate was about 0.047×108 t/a. The relationship between water and sediment in Wei River Basin can be divided into two phases i.e., from 1940-1970s and after 1970s. From the 1940s to 1970s, there was less human activity, such as soil and water conservation, in the Wei River Basin, so the runoff and sediment yield changes were mainly affected by climate change. When the runoff was larger, the sediment load was larger and when the runoff was smaller, the sediment load was also smaller. After 1970s, large-scale measures of soil and water conservation were developed, which has great impact on soil erosion and sediment yield of basin and resulted in changing of laws between the runoff and sediment load. When the runoff was larger, the sediment load was smaller and when the runoff was smaller, the sediment load was also smaller, especially after 1997. It was concluded that the soil and water conservation play an important role in the reduction of the sediments of river. And when the comprehensive treatment reaches a certain level of governance, it has positive environmental benefits for both sediment and runoff.
اظهر المزيد [+] اقل [-]Research of Interpolation and Prediction by Elman NN on Anaerobic Digestion Processes Parameter
2015
Liang Yong | Qiu Ling | Pan Junting | Lu Wen
Parametric data from anaerobic digestion processes are normally collected once every couple of days and not daily. As a result, only a small amount of data could be collected and this is not sufficient for the neural network analysis. In this research, interpolations were used during the modelling process to increase the sample data used for Elman neural network (Elman NN) modelling. Laboratory digestion of silage cornstalk was conducted for 54 days, and a portion of the biogas data was used for training the Elman neural network (Elman NN) model, while the remaining biogas data were used to verify the prediction capability of the model. Compared to the Elman NN model without interpolations, using an interpolation coefficient of 0.2 increased the number of experimental data from 54 to 266 and the correlation coefficient of prediction data and sampling data from 0.7966 (for no-interpolation) to 0.9962 (for cubic spline interpolation) and 0.9942 (for piecewise linear interpolation). In addition, the mean square error decreased from 0.1190 (for no interpolation) to 0.001 (for cubic spline interpolation) and 0.001 (for piecewise linear interpolation), while the average relative error decreased from 63.04% (for no interpolation) to 3.93% (for cubic spline interpolation) and 4.01% (for piecewise linear interpolation). The Elman NN simulation results thus showed that the interpolation algorithm can greatly improve the prediction accuracy of biogas production from an anaerobic digestion process.
اظهر المزيد [+] اقل [-]Wind Environment in Green Building Design
2015
Yang Li | Qian Feng
With the increasing urban building density, wind environment problems around the buildings become more and more serious. Wind environment not only affects human living comfort, but also closely relates to their security and health. So, it is important to study the wind environment to improve it in the building planning and design and it is also an important part of making a reasonable evaluation of wind environment in green building design. In the current study, wind tunnel test and numerical simulation of computer technology are considered as an effective means of simulation and validation of environment.
اظهر المزيد [+] اقل [-]Decolorization of Leather Dyeing Wastewater by Laccase of the White Rot Fungus Pycnoporus sp. Y1
2015
Lu Xinli | Zhao Chun Hai | Zhao Aijun | Zhang Yuqi | Wu Yichun
In this study, laccase produced by the white rot fungus strain Pycnoporus sp. Y1 was used for the leather dyeing wastewater decolorization. The mediators including veratryl alcohol (VA), 2,2’-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), hydroxybenzoic acid (HA), hydroxybenzotrizole (HOBT), and temperature, pH values, laccase concentration, and leather dyeing wastewater dilution ratio were all investigated in the experiments, and then four factors (mediators, temperatures, pH values, dilution ratios) were optimized by orthogonal experimental design. The optimal conditions for wastewater decolorization were obtained as follows: temperature of 50°C, pH 3.0, laccase concentration 4 U/mL, and the dilution ratio of 1-fold, the decolorization ratio could reach 58.42% in 10 min under the optimized conditions at last.
اظهر المزيد [+] اقل [-]Research on H2S Removal by the Ferric Oxide Process
2015
Zhou Jihong | Jiang Qi | Wen Yamin | Liang Ronghe
The removal of hydrogen sulphide by using the method of dry desulphurization in a normal temperature iron oxide is introduced in this paper. The experiment has been conducted by using the ferric oxide as the desulphurizer in the waste red mud and added wood chips and calcium oxide for the removal of hydrogen sulphide. Also, the desulphurization efficiency of desulphurizer is researched in different drying temperatures and different ratio conditions, and the best condition of removing hydrogen sulphide is studied. The results of the studies show that the best conditions of removing hydrogen sulphide are 80% of red mud, 5% of wood chips and 15% of calcium oxide at 110°C drying temperature | 85% of red mud, 5% of wood chips and 10% of calcium oxide at 130°C drying temperature | and 70% of red mud, 5% of wood chips and 25% of calcium oxide at 150°C drying temperature. In three different drying temperatures, the best ratio is 85% of red mud, 5% of wood chips, 10% of calcium oxide, and the best drying temperature is 130°C. This test also provides technical support for further industrial utilization.
اظهر المزيد [+] اقل [-]Effects of Climate Change on Vegetable Cultivation - A Review
2015
Prasad B. V. G. | Chakravorty S.
World population is increasing at an alarming rate and is expected to reach about six billion by the end of year 2050. Increased hunger and malnourishment are challenging issues for all nations, especially those who are resource poor. Feeding of hunger-laden people of the world not only requires food in quantity but quality as well. Vegetables are protective foods embedded with vitamins, micronutrients, pharmaceutical and nutraceutical compounds, which are necessary for correction of diseases and disorders. Moreover, cultivation of vegetables provides livelihood security through employment. But the complex process of growth and development is significantly affected by different agro-climatic factors and therefore, any environmental aberration due to climate change can impose unprecedented stress on this group of plants which may lead to complete failure of the crop in a grower’s field. Usually extreme temperatures, limited soil moisture, reduced availability of irrigation water, repeated flooding, increased acidity or salinity and soil erosion, high wind speed, increase in occurrence of hails and thunderstorms, frost damage and tsunamis etc., are the major limiting factors for optimum productivity besides the quality and consumer acceptance. Sudden change in climate also influences the status of soil fertility, occurrence of pests and diseases, host-pathogen interactions, soil microbial population and behaviour of the pollinators. Reduced production and productivity due to the development of genetically weakened seeds is the ultimate outcome of climate change which may invite a crisis in food reserve in the future. All these have significant effects on the total vegetable cultivation system on the planet, affecting the economic yield, which is of prime importance from grower’s point of view. Hence, there is a need to develop an understanding of the impacts and implications of climate change on vegetable cultivation for timely intervention to ameliorate its harmful effects.
اظهر المزيد [+] اقل [-]Effects of FDI on Environment Pollution based on Carbon Dioxide Emissions in the Pearl River Delta Region
2015
Guo Hao | Tang Jie | Wang Dong | Chen Furong | Lin Lianlian
Issues related to global climate change have attracted widespread attention around the world, and China is no exception. With the introduction of a huge number of foreign direct investment (FDI), carbon dioxide emission pollution, such as ocean acidification, has become a serious threat in the Pearl River Delta (PRD) region. This study constructs models to analyse the effects of FDI on carbon dioxide emissions in the PRD region, as well as to analyse the scale, technique and composition effects in the area. Results indicate that the introduction of FDI can effectively reduce carbon dioxide emissions in the region because the foreign capital could bring environmental-friendly and energy-saving technologies, reduce carbon dioxide emissions per unit of GDP, and lessen damage to the environment. In addition, foreign capital flowing into the secondary sector has caused more serious damage to the environment than those flowing into the tertiary sector. Therefore, the area should actively guide foreign investment into industries with lower pollution and lower emissions. At the same time, strict standards should be developed to slow down the inflow of foreign capital in sectors which are energy-intensive, environmentally damaging, and have low levels of value-added production.
اظهر المزيد [+] اقل [-]Growth Characteristics of Platymonas subcordiformis and Oxyrrhis marina in Their Co-culture Systems
2015
An Xinlong | Li Xuemei | Li Zhixia | Zhang Yanling
This study was aimed to investigate the growth characteristics of living diet Platymonas subcordiformis for aquaculture animals and its harmful organism Oxyrrhis marina in co-culture systems to provide experimental evidences for discussing their succession processes. The colour changes of culture media of P. subcordiformis and growth characteristics of O. marina and P. subcordiformis in co-culture were analysed by the combined methods of macro-observation, microscopic examination and microscopic counting. The results showed that with the decrease of the initial density of O. marina cell (0.65×104 cells mL-1, 0.37×104 cells mL-1 and 0.11×104 cells mL-1 in P. subcordiformis culture media), the time that the population of O. marina reached the stationary phase required longer, were 4d, 5d and 7d after inoculated by O. marina, respectively, and the death time of all cells of P. subcordiformis became longer, were 9d, 10d and 12d after inoculated by O. marina, respectively. After inoculation 9d, pale pink appeared in upper layer of culture media of P. subcordiformis in flasks and the density of O. marina was 2.10×105 cells mL-1. The results also indicated that the variation tendency of cell densities of O. marina and P. subcordiformis cultured in aquariums were consistent with that in flasks basically, pink flocs appeared in upper layer of culture media of P. subcordiformis after inoculation 12d and the density of O. marina was 2.10×106 cells mL-1. The experimental results showed that the feeding of O. marina on P. subcordiformis was affected by the initial concentration of O. marina, and P. subcordiformis populations were evolved to O. marina populations during the 15 days culture period, the colour of culture media appeared pale pink to pink depends on density of O. marina was confirmed, too. Also, the colour changes of P. subcordiformis culture media are indications of pollution by O. marina, which will be important for culture process of P. subcordiformis.
اظهر المزيد [+] اقل [-]Application of D Numbers to the Environmental Impact Assessment of HighwayApplication of D Numbers to the Environmental Impact Assessment of Highway
2015
Sepahvand Leila
Environmental impact assessment (EIA) is an important technique to ensure that possible effects of developmental projects have been fully identified and calculated for environment, and also its main purpose is accurate predicting, identifying and analysing the all positive and negative impacts on the natural and human environment. Assessment of the environmental impact requires a method or methods to do it. Due to the lack of sufficient knowledge, potential effects of projects are qualitative for nature, and they cannot be numerical exactly. One way to overcome this problem is using different types of uncertainty on EIA process. The theory of D numbers is a new provision of unreliable information and it is developed version of Dempster-Shafer theory. In this research, an assessment of environmental impact arising from the construction and operation of Ghomeishlou highway has been evaluated using D theory of numbers.
اظهر المزيد [+] اقل [-]Evaluating the Radiation Risk of Ionization Smoke Detector by MCNPX code; A Radioactive Contaminated Product
2015
Khaleghi M. | Hashemi-Tilehnoee M.
Ionization smoke sensors are the best smoke sensors | however, the small amount of radioactive source they include is no longer desirable since it makes recycling more complicated where the people encountered with radioactive waste. In this study, a conventional ionization type smoke sensor which contained americium-241 radioactive source modelled by Monte Carlo MCNPX code. The absorbed dose rate is calculated by MCNPX code where the human tissue meddled as a soft tissue material. The dosimetry results are comparable with the experimental safety margins. It concluded that if the ionization smoke sensors positioned at a right distance from the human body, so the radiation risk and the exposure hazard can be lower than the exposure level of the background radiation.
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