The contemporary demands of the forestry exploitation for quantitative and qualitative increase of timber production are directly related with the mechanization of the wood skidding works. In Greece, the suitable mach...The contemporary demands of the forestry exploitation for quantitative and qualitative increase of timber production are directly related with the mechanization of the wood skidding works. In Greece, the suitable machinery for wood skidding are those with low amortization, operation and installation expenses, are flexible, and may also be used for other farming works （since they are not used very often for wood skidding） and cause the smaller damages to the wood, the forest, the soil and the environment in general. In this paper, it studies the environmental impacts in the remaining stand as much as during the pre-skidding as well as during the main wood skidding with tractor in the forest of Arnaia, Prefecture of Halkidiki, in order to draw out useful conclusions for the improvement of the machinery application methods and the protection of the environment.展开更多
Mooring,towing and installing tests on immersed tunnel caissons across the Yong River are carried out in basin to investigate the motions and line tensions.In the towing operation,the maximum tension exists in the cas...Mooring,towing and installing tests on immersed tunnel caissons across the Yong River are carried out in basin to investigate the motions and line tensions.In the towing operation,the maximum tension exists in the case that half caisson is exposed to waves and currents.The cooperation of operating manually on many lines at the same time is very difficult and important.The dynamic behavior of the caisson and the line tensions are affected more by the manual operations than by waves and currents.In the installing operation,the tensions of hoisting lines are much larger than the positioning lines.展开更多
文摘The contemporary demands of the forestry exploitation for quantitative and qualitative increase of timber production are directly related with the mechanization of the wood skidding works. In Greece, the suitable machinery for wood skidding are those with low amortization, operation and installation expenses, are flexible, and may also be used for other farming works （since they are not used very often for wood skidding） and cause the smaller damages to the wood, the forest, the soil and the environment in general. In this paper, it studies the environmental impacts in the remaining stand as much as during the pre-skidding as well as during the main wood skidding with tractor in the forest of Arnaia, Prefecture of Halkidiki, in order to draw out useful conclusions for the improvement of the machinery application methods and the protection of the environment.
基金the Science and Technology Committee of Shanghai (No. 07DZ22027)
文摘Mooring,towing and installing tests on immersed tunnel caissons across the Yong River are carried out in basin to investigate the motions and line tensions.In the towing operation,the maximum tension exists in the case that half caisson is exposed to waves and currents.The cooperation of operating manually on many lines at the same time is very difficult and important.The dynamic behavior of the caisson and the line tensions are affected more by the manual operations than by waves and currents.In the installing operation,the tensions of hoisting lines are much larger than the positioning lines.
