Forest Potential Productivity (FPP) of 8 counties in Tianshan was cal culated, and the potential timber output of these counties was analyzed with Mia mi Model and Thornthwaite Memorial Model. Research results showed ...Forest Potential Productivity (FPP) of 8 counties in Tianshan was cal culated, and the potential timber output of these counties was analyzed with Mia mi Model and Thornthwaite Memorial Model. Research results showed that annual av erage output of present stand in Tianshan Forest Region was 3.7 m3/(hm2. a), whi ch reached only 49% of average FPP.展开更多
The 2-dimensional equivalent model used in helicopter ground resonance analysis is convenient for its simplicity and clarity. The equivalent body mass, the stiffness and the damping are derived from the modal charaCte...The 2-dimensional equivalent model used in helicopter ground resonance analysis is convenient for its simplicity and clarity. The equivalent body mass, the stiffness and the damping are derived from the modal charaCteristics. In this paper, a 3-dimensional space model is constructed to analyse the ground resonance.There is little difference between the calculated results of the 2-dimensional equivalent model and those of the 3-dimensional space model. Hence, the 2-dimensional model is verified for the practical application. Generally, the linear lead-lag damping of the equivalent rotor blade at the modal frequency is derived from the lead-lag damper characteristics by a procedure of iteration. The transformation of the imaginary part of the complex modulus of the viscoelastic damper into a linear velocity damping is complicated in analysis. A method to use the complex modulus directly in the ground resonance analysis is derived and verified.展开更多
文摘Forest Potential Productivity (FPP) of 8 counties in Tianshan was cal culated, and the potential timber output of these counties was analyzed with Mia mi Model and Thornthwaite Memorial Model. Research results showed that annual av erage output of present stand in Tianshan Forest Region was 3.7 m3/(hm2. a), whi ch reached only 49% of average FPP.
文摘The 2-dimensional equivalent model used in helicopter ground resonance analysis is convenient for its simplicity and clarity. The equivalent body mass, the stiffness and the damping are derived from the modal charaCteristics. In this paper, a 3-dimensional space model is constructed to analyse the ground resonance.There is little difference between the calculated results of the 2-dimensional equivalent model and those of the 3-dimensional space model. Hence, the 2-dimensional model is verified for the practical application. Generally, the linear lead-lag damping of the equivalent rotor blade at the modal frequency is derived from the lead-lag damper characteristics by a procedure of iteration. The transformation of the imaginary part of the complex modulus of the viscoelastic damper into a linear velocity damping is complicated in analysis. A method to use the complex modulus directly in the ground resonance analysis is derived and verified.
