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971.
针对电梯群控调度过程中交通特性的不确定性,建立了包括最短候梯时间,最短乘梯时间和最少能耗的电梯群控系统的模型,提出了一种适应电梯群控性能需求的伪微分反馈控制算法,并对算法进行改进来达到更好的调度效果,最后进行仿真实验.仿真结果表明该方法与其他算法相比在电梯群控调度性能和交通模式的适应性方面有较大的改善。 相似文献
972.
973.
A Ka‐band 6‐W high power microwave monolithic integrated circuit amplifier for use in a very small aperture terminal system requiring high linearity is designed and fabricated using commercial 0.15‐μm GaAs pHEMT technology. This three‐stage amplifier, with a chip size of 22.1 mm2 can achieve a saturated output power of 6 W with a 21% power‐added efficiency and 15‐dB small signal gain over a frequency range of 28.5 GHz to 30.5 GHz. To obtain high linearity, the amplifier employs a class‐A bias and demonstrates an output third‐order intercept point of greater than 43.5 dBm over the above‐mentioned frequency range. 相似文献
974.
Multi-harmonic active structural acoustic control of a helicopter main transmission noise using the principal component analysis 总被引:1,自引:0,他引:1
This paper evaluates the feasibility and effectiveness, under controlled conditions, of active structural acoustic control of a helicopter main transmission in order to attenuate the vibration of the receiving roof panel and its sound radiation into the cabin. The vibroacoustic analysis of a typical helicopter drive train is conducted to extract the dominant tones generated by the various transmission stages. A finite element model of a Bell 407 transmission and simplified roof structure is developed in order to investigate various active control arrangements using piezoceramic actuators to control wave propagation in the gearbox supporting struts or receiving panel. The principal component analysis is used to extract the most significant control paths and reduce the control effort. A multiple frequency principal component least mean square (PC-LMS) algorithm is implemented on a laboratory setup and is used to successfully reduce up to seven gearbox tones simultaneously. 相似文献
975.
We have demonstrated a Q-switched fiber laser based on a mechanical all-fiber Q-switching module and pulsed-pump configuration. A piezoelectric actuator was utilized in the module to change the round-trip loss of the fiber laser cavity, and exploited the pulsed pump to prevent the multiple pulsing phenomena. Q-switching pulses were successfully achieved at the repetition rates from 1 Hz to 2 kHz, and the average output power was 11 mW. The peak power in excess of 114 W with associated pulse width of 193 ns was obtained at the repetition rate of 500 Hz. Besides preventing multiple pulsing phenomena, pulsed-pump configuration can also suppress amplified spontaneous emission and increase pulse stability and peak power simultaneously. 相似文献
976.
有/无金属离子Cu2+或Zn2+参与时中药有效成分伞形花内酯与生物大分子BSA的相互作用 总被引:4,自引:0,他引:4
运用荧光光谱(FS)及紫外光谱(UV)研究了有/无金属离子Cu2 或Zn2 参与时中药有效成分伞形花内酯与生物大分子牛血清白蛋白(BSA)的相互作用。实验结果表明:有/无金属离子参与时,伞形花内酯均与BSA形成基态复合物从而猝灭BSA的内源性荧光,猝灭原因主要为静态猝灭和非辐射能量转移;金属离子参与使得KA增大,n仍维持在2左右;伞形花内酯分子能够扦插入BSA分子内部,温度以及金属离子参与对伞形花内酯与BSA分子中荧光性氨基酸残基间的空间距离r影响不大。有/无金属离子参与时伞形花内酯与BSA的作用过程均是一个熵增加和Gibbs自由能降低的自发超分子作用过程。伞形花内酯与BSA之间以静电相互作用为主,金属离子参与使伞形花内酯与BSA分子间静电相互作用增强,故ΔH对ΔG的贡献增大。 相似文献
977.
Zou HC Lü ZR Wang YJ Zhang YM Zou F Park YD 《Applied biochemistry and biotechnology》2009,152(1):15-28
We studied the effect of cysteine modification on creatine kinase (CK) aggregation as well as the kinetics of the process.
We found that CK aggregation was modulated by different pH conditions in the presence of Zn2+, which is a CK aggregation trigger. The CK aggregation followed first-order kinetics, and this was effectively suppressed
in acidic conditions. Even under the acidic condition, cysteine modification at the active site with using 5,5′-dithiobis-2-nitrobenzoic
acid (DTNB) induced conspicuous aggregation in a dose-dependent manner. This aggregation process is directly related with
decreasing the change of transition free-energy (ΔΔG
AG
). When dithiothreitol (DTT) was applied to the reaction system, the aggregates were significantly reduced: DTT treatment
can fully reactivate (higher than 80%) the inactive CK that was separated from CK aggregates, whereas CK was completely inactivated
by Zn2+ and DTNB. Some added osmolytes such as glycine and proline were able to successfully block CK aggregation by increasing the
ΔΔG
AG
as well as by suppressing the hydrophobic CK surface. Our study suggests the effect of cysteine modification on the unfavorable
aggregation of CK and on the aggregation process that followed first-order kinetics with the accompanying changes of transitional
free energy and disruptions of the hydrophobic surface. We also demonstrate the successful protocol to block the aggregation. 相似文献
978.
979.
In this paper, we develop dissipativity theory for discontinuous dynamical systems. Specifically, using set-valued supply rate maps and set-valued connective supply rate maps consisting of locally Lebesgue integrable supply rates and connective supply rates, respectively, and set-valued storage maps consisting of piecewise continuous storage functions, dissipativity properties for discontinuous dynamical systems are presented. Furthermore, extended Kalman–Yakubovich–Popov set-valued conditions, in terms of the discontinuous system dynamics, characterizing dissipativity via generalized Clarke gradients and locally Lipschitz continuous storage functions are derived. Finally, these results are used to develop feedback interconnection stability results for discontinuous dynamical systems by appropriately combining the set-valued storage maps for the forward and feedback systems. 相似文献
980.