Effects of Plants for Gravity Erosion on the Loess Gully Sidewall under Intense Rainfalls

<p>To study the mechanism of vegetation on gravity erosion may provide the theoretical basis for the design of soil and water conservation on the Loess Plateau, China. This study explores the effects of vegetation on the gravity erosion using the models of loess gully sidewall with the slope degree of 70 ° and height of 1.5 m under series of rainfall simulations, in which vegetational and bare lands were used, respectively. The experimental results are shown as follows: (1) The influence of the vegetation on the total amount of gravity erosion may be ignored. The average amount of gravity erosion for each event of rainfall on the vegetational sidewall was only decreased by 12% compared with that on the bare sidewall. (2) The plant had a positive effect on the mass failures after rainfalls. The ratio of the failure mass volume after rainfall to the total on the planted slope was almost 12%, while the ratio on the bare slope was only 1%. (3) The vegetation on the gully sidewall had different influences on the varied types of gravity erosion. Compared with those on the bare land, the average amounts of the avalanche and mudslide on the vegetational slope was decreased by 72% and 69%, respectively. In the meantime, the average amount of landslide in the vegetational slope was increased by 220% compared with that in bare slope. (4) The effects of vegetation on gravity erosion were caused by several factors. The plant roots may reinforce the soil and reduce the amount of gravity erosion, but the self-gravity of the plant and increase of the permeability on the planted slope might increase the gravity erosion. In addition, the soil permeability was increased by the plant roots, which could intensify the landslides. As a result, the plant practice was preferable for the sidewall vulnerable to mudslide. The results may be referred to analyze the mechanism of gravity erosion and design the control of mass failure.</p>

Impact of ownership change on plant practice-performance dynamics

Purpose – Ownership change has been an overlooked contingency factor in past plant level practice-performance studies. Therefore, the purpose of this paper is to examine the impact of ownership changes to practice-performance dynamics by longitudinally following the same 23 manufacturing sites from year 1993 to 2010. Design/methodology/approach – Interview data of the made in Finland – study are used for presenting different paths of plant development in the long term. Both narratives and descriptive statistics are used to support the analysis. Findings – The findings suggest that the benefits of long-term domestic ownership may in fact exceed the positive knowledge spill-over effects that derive from foreign acquisitions. Foreign acquirers seem to “cherry-pick” well-performing sites. Also it seems that the likelihood of inferior performance and plant shutdowns may increase due to foreign acquisitions. Research limitations/implications – Due to the exploratory nature of the study the sample size did not allow for testing statistical significance of the results. Originality/value – The exploratory findings of the study open new avenues of theory development for practice-performance studies, and corroborate research in other disciplines such as economics and corporate governance.

Coupling model and solving approach for performance evaluation of natural draft counter-flow wet cooling towers

When searching for the optimum condenser cooling water flow in a thermal power plant with natural draft cooling towers, it is essential to evaluate the outlet water temperature of cooling towers when the cooling water flow and inlet water temperature change. However, the air outlet temperature and tower draft or inlet air velocity are strongly coupled for natural draft cooling towers. Traditional methods, such as trial and error method, graphic method and iterative methods are not simple and efficient enough to be used for plant practice. In this paper, we combine Merkel equation with draft equation, and develop the coupled description for performance evaluation of natural draft cooling towers. This model contains two inputs: the cooling water flow, the inlet cooling water temperature and two outputs: the outlet water temperature, the inlet air velocity, equivalent to tower draft. In this model, we furthermore put forward a soft-sensing algorithm to calculate the total drag coefficient instead of empirical correlations. Finally, we design an iterative approach to solve this coupling model, and illustrate three cases to prove that the coupling model and solving approach proposed in our paper are effective for cooling tower performance evaluation.

Experimental Research on Rough Flotation of Lead in Bainiuchang Lead-Zinc Mines

Containing Pb (1.09% ) and Zn (1.97%),the lead-zinc sulphide ore of Bainiuchang mine is a refractory resource in Yunnan Mengzi. The flotation performance of lead is ineffective in plant practice. This research is carried out to enhance the rough flotation performance of lead. With the dosage of lime and zinc sulfate as depressors, sodium hexametaphosphate as dispersant, and ethyl thio carbamate and MA as combined collector, the grinding fineness of 85% , a lead concentrate with lead grade of 17.68%, lead recovery rate of 75.59%, and zinc grade of 7.16% was obtained. The performance of rough flotation of lead is improved.