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采用调速稳速集成电路通过电位调节买现自反馈电子稳速，克服了实验过程中溶液阻尼变化对电机转速的影响，并利用高精度时钟信号与十进制记数器完成光电测速过程。 相似文献
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Asynchrony of spring phytoplankton response to temperature driver within a spatial heterogeneity bay of Three-Gorges Reservoir, China 总被引：3，自引：0，他引：3
The increased air temperature is expected to have important driver on spring phytoplankton dynamics. To test whether spatial heterogeneity modifies the synchronous responses of phytoplankton to regional temperature driver, we evaluate temporal coherences for physical factors (temperature, water stability and non-algal light extinction), nutrients (nitrogen, phosphorus and silicon), and biomass and density of phytoplankton by Pearson correlation analysis and synchrony for phytoplankton community dynamics by Mantel test and nonmetric multi-dimensional scaling (NMS), during spring bloom (February 23–April 28, 2005) within Xiangxi Bay, a high spatial gradient bay of Three-Gorges Reservoir (China). The high level of temporal coherences for surface water temperature (r = 0.946, p < 0.01) and relative water column stability (r = 0.750, p < 0.01) were found between pair sites (A and B), in which the increase trends occurred with increase in regional air temperature during the study period. However, the low synchrony for phytoplankton dynamics were indeed observed between Site A and B, especially for the density of common dominant taxa (Cyclotella spp.: r = 0.155, p = 0.388) and community structure (Mantel test: r = 0.351). Moreover, the local habitat characteristics such as nutrient (nitrogen and phosphorus) and non-algal light extinction showed low levels of temporal coherence. It indicated that local community of phytoplankton varies rather independently within the single lentic bay with high spatial heterogeneity and that dispersal of algal organisms among locations cannot overwhelm out these local dynamics. Contrary to many studies, the present results argued that, in a small geographic area (i.e., a single reservoir bay of approximately 24 km length), spatial gradients also may influence spring phytoplankton response to regional temperature driver. 相似文献
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印支造山期结束以后,蛇场背斜南翼三叠系在倾斜的基盘上,曾一度象冰川一样在自身重力的作用下,自北向南脱顶滑移,并造成锑的成矿控矿构造。着重叙述了这类构造的发育机制及特征,并探讨其对锑矿床赋存状态的控制作用。 相似文献
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Large volume airgun arrays have been widely used in exploring and monitoring underground structures for nearly a decade. Nowadays, large volume airgun arrays adopt the synchronous excitation mode, and source characteristics are controlled by the source signal of a single airgun, which to some extent limits its application. In order to realize the asynchronous excitation of the airgun array, we developed a new firing system for the airgun array, and carried out a field experiment in the Binchuan Fixed Airgun Signal Transmission station to study the influences of the asynchronous excitation on the source signal. The experimental results show that:the newly developed airgun array firing system can ignite the airguns according to the setting time series with high precision. By designing the excitation time series, the asynchronous excitation can enhance the energy of airgun source signal at 3-5Hz, and reduce the energy of pressure pulse wave at 6-18Hz. The signal detection capability of the asynchronous excitation with time series mode is equivalent to the synchronous excitation. 相似文献
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完成了基于TMS320VC5402 DSP的RS_485通信的硬件设计和软件编程.基于美国TI公司TMS320VC5402 DSP芯片的多通道缓冲口(McBSP)进行适当的硬件扩展,以SPI方式直接和MAXIM公司的MAX3100通用异步串行收发器接口,然后经Linear Technology公司的LTC1480超低功耗RS_485收发器,从而实现了一种新的基于RS_485标准接口串行通讯的数据传输,充分利用了DSP的片上资源,使硬件和软件结构尽量简单化. 相似文献
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