数字滤波器的功能是对输入离散的数字信号进行运算处理，以达到改变信号频谱的目的。System Generator是基于定点的仿真系统。的本设计内容全部基于System Generator。首先由DDS（Direct Digital Synthesizer数字信号发生器）生成正弦...数字滤波器的功能是对输入离散的数字信号进行运算处理，以达到改变信号频谱的目的。System Generator是基于定点的仿真系统。的本设计内容全部基于System Generator。首先由DDS（Direct Digital Synthesizer数字信号发生器）生成正弦波信号，之后加入高斯白噪声，将信号通过两种结构的数字滤波器进行滤波，随后将程序下载至FPGA中，通过DA将信号输出，最后在比较两种滤波器的在硬件平台上的实际性能以及消耗资源情况。展开更多
Quercus gambelii (Gambel’s oak) communities are found in the mountains of the western United States from Wyoming, Colorado, and Utah south into northern Mexico. Leaf gas exchange rates were measured for potential suc...Quercus gambelii (Gambel’s oak) communities are found in the mountains of the western United States from Wyoming, Colorado, and Utah south into northern Mexico. Leaf gas exchange rates were measured for potential successional species in Q. gambelii communities. Daily average light level below the canopy was 125 μmol/m2/sec. Light response curves indicated that Pinus ponderosa and Q. gambelii had high maximum photosynthetic rates (14.13 and 11.21 μmol/m2/sec) and were sun species. Abies concolor (white fir) is a shade species with the lowest photosynthetic rate (3.71 μmol/m2/sec). At low light levels few differences in photosynthetic rates were found between the species. Pinus ponderosa and Q. gambelii maximum photosynthetic rates were reduced 71% - 73% in shade and the shade species maximum photosynthetic rates were reduced by 50% - 57%. Comparing annual gas exchange rates for all species showed that A. concolor had higher gas exchange rates and could replace Q. gambelii. Growth in height of Q. gambelii was a second order quadratic function reaching a plateau of about ten meters between 80 and 95 years. Growth estimates of height of A. concolor in canopy shade were exponential, which would allow seedlings to reach the Q. gambelii canopy in approximately 35 years. Abies concolor wood specific gravity is 56% lower than Q. gambelii, which means more carbon is put into growth in height to reach the canopy at low light levels and low photosynthetic rates. The additional shading it causes would further reduce Q. gambelii photosynthesis rates and prevent self-replacement in these Q. gambelii communities, leading to an A. concolor dominated community.展开更多
文摘数字滤波器的功能是对输入离散的数字信号进行运算处理，以达到改变信号频谱的目的。System Generator是基于定点的仿真系统。的本设计内容全部基于System Generator。首先由DDS（Direct Digital Synthesizer数字信号发生器）生成正弦波信号，之后加入高斯白噪声，将信号通过两种结构的数字滤波器进行滤波，随后将程序下载至FPGA中，通过DA将信号输出，最后在比较两种滤波器的在硬件平台上的实际性能以及消耗资源情况。
文摘Quercus gambelii (Gambel’s oak) communities are found in the mountains of the western United States from Wyoming, Colorado, and Utah south into northern Mexico. Leaf gas exchange rates were measured for potential successional species in Q. gambelii communities. Daily average light level below the canopy was 125 μmol/m2/sec. Light response curves indicated that Pinus ponderosa and Q. gambelii had high maximum photosynthetic rates (14.13 and 11.21 μmol/m2/sec) and were sun species. Abies concolor (white fir) is a shade species with the lowest photosynthetic rate (3.71 μmol/m2/sec). At low light levels few differences in photosynthetic rates were found between the species. Pinus ponderosa and Q. gambelii maximum photosynthetic rates were reduced 71% - 73% in shade and the shade species maximum photosynthetic rates were reduced by 50% - 57%. Comparing annual gas exchange rates for all species showed that A. concolor had higher gas exchange rates and could replace Q. gambelii. Growth in height of Q. gambelii was a second order quadratic function reaching a plateau of about ten meters between 80 and 95 years. Growth estimates of height of A. concolor in canopy shade were exponential, which would allow seedlings to reach the Q. gambelii canopy in approximately 35 years. Abies concolor wood specific gravity is 56% lower than Q. gambelii, which means more carbon is put into growth in height to reach the canopy at low light levels and low photosynthetic rates. The additional shading it causes would further reduce Q. gambelii photosynthesis rates and prevent self-replacement in these Q. gambelii communities, leading to an A. concolor dominated community.
