The problem of global stabilization by state feedback for a class of time-delay nonlinear system is considered. By constructing the appropriate Lyapunov-Krasovskii functionals (LKF) and using the backstepping design, ...The problem of global stabilization by state feedback for a class of time-delay nonlinear system is considered. By constructing the appropriate Lyapunov-Krasovskii functionals (LKF) and using the backstepping design, a linear state feedback controller making the closed-loop system globally asymptotically stable is constructed.展开更多
In this paper, the stability of a concave spherical stem bulkhead under the pumping load when still lying at the slipway is analyzed. The stability of the spherical stem bulkhead with different shell thickness and rei...In this paper, the stability of a concave spherical stem bulkhead under the pumping load when still lying at the slipway is analyzed. The stability of the spherical stem bulkhead with different shell thickness and reinforcing forms is discussed. According to the results of stability analysis, the optimization design of the spherical stem bulkhead stability is performed. On the basis of considering the machining technical requirements of the bulkhead, a rational design of the spherical stem bulkhead structure is obtained. This paper has a certain value to the design of submarine's spherical stem bulkhead.展开更多
Spherical mesoporous ZrO_(2)-Al_(2)O_(3) composites containing different zirconia content have been synthesized by an oil-column sol-gel method.A mixed alumina-zirconia hydrosol and hexamethylenetetramine solution wer...Spherical mesoporous ZrO_(2)-Al_(2)O_(3) composites containing different zirconia content have been synthesized by an oil-column sol-gel method.A mixed alumina-zirconia hydrosol and hexamethylenetetramine solution were mixed together and added dropwise into a hot oil column.Due to the surface tension,spherical gel particles were formed in the oil column.The spherical gel particles were then aged and washed by deionized water and dried at 120 ℃ for 12 h and then calcined at 600 ℃ for 8 h,960 ℃ for 8 h or 1200 ℃ for 12 h.X-ray diffraction and nitrogen adsorption-desorption measurements indicated that the presence of zirconia prevents the sintering of alumina and the obtained ZrO_(2)-Al_(2)O_(3) composites have much larger surface areas than pure alumina.Temperature-programmed desorption of ammonia results illustrated that the addition of zirconia leads to an increase in the number of strong acid sites and the total number of acid sites compared with pure alumina.Thus,the spherical mesoporous ZrO_(2)-Al_(2)O_(3) composites prepared in this way were shown to be suitable for high temperature catalytic processes as a catalyst support.展开更多
基金Supported by the "973" Project of P. R. China (G1998020300)
文摘The problem of global stabilization by state feedback for a class of time-delay nonlinear system is considered. By constructing the appropriate Lyapunov-Krasovskii functionals (LKF) and using the backstepping design, a linear state feedback controller making the closed-loop system globally asymptotically stable is constructed.
文摘In this paper, the stability of a concave spherical stem bulkhead under the pumping load when still lying at the slipway is analyzed. The stability of the spherical stem bulkhead with different shell thickness and reinforcing forms is discussed. According to the results of stability analysis, the optimization design of the spherical stem bulkhead stability is performed. On the basis of considering the machining technical requirements of the bulkhead, a rational design of the spherical stem bulkhead structure is obtained. This paper has a certain value to the design of submarine's spherical stem bulkhead.
基金supported by the National Natural Science Foundation of Chinathe 111 Project (B07004)the Program for Changjiang Scholars and Innovative Research Teams in Universities (IRT0406)
文摘Spherical mesoporous ZrO_(2)-Al_(2)O_(3) composites containing different zirconia content have been synthesized by an oil-column sol-gel method.A mixed alumina-zirconia hydrosol and hexamethylenetetramine solution were mixed together and added dropwise into a hot oil column.Due to the surface tension,spherical gel particles were formed in the oil column.The spherical gel particles were then aged and washed by deionized water and dried at 120 ℃ for 12 h and then calcined at 600 ℃ for 8 h,960 ℃ for 8 h or 1200 ℃ for 12 h.X-ray diffraction and nitrogen adsorption-desorption measurements indicated that the presence of zirconia prevents the sintering of alumina and the obtained ZrO_(2)-Al_(2)O_(3) composites have much larger surface areas than pure alumina.Temperature-programmed desorption of ammonia results illustrated that the addition of zirconia leads to an increase in the number of strong acid sites and the total number of acid sites compared with pure alumina.Thus,the spherical mesoporous ZrO_(2)-Al_(2)O_(3) composites prepared in this way were shown to be suitable for high temperature catalytic processes as a catalyst support.
