相控阵雷达波束控制器优化设计

在雷达控制优化设计的研究中,针对相控阵天线波束要求波束扫面快、灵活的问题,提出了采用可编程控制逻辑门阵列(FPGA)的数字波束形成技术,难点在于波控码的计算。通过比较采用了查表法,即先把需要的三角函数的值以及系数的值计算好,放在不同的RAM中,通过外部接口接收来自上位机的信号工作频率,方向角以及俯仰角的参数。参数会通过给定的通信协议,转化为十六进制送进去,相当于查找表中对应的所需数据的地址,在RAM中查找到所需的值调用,然后计算出雷达阵列中的每个雷达的移相码,送到每个移相器中。通过仿真,以及最后的测试表明,改进方法可以快速而准确的计算出每个天线单元所需的移相码,并能同步的把各个波控码送给对应的移相器上。

盘式制动器、制动盘的安装质量控制和检查方法

介绍了盘式制动器的安装质量、检查方法。

Bus Encoded LUT Multiplier for Portable Biomedical Therapeutic Devices

DSP operation in a Biomedical related therapeutic hardware need to beperformed with high accuracy and with high speed. Portable DSP hardware’s likepulse/heart beat detectors must perform with reduced operational power due to lack ofconventional power sources. This work proposes a hybrid biomedical hardware chip inwhich the speed and power utilization factors are greatly improved. Multipliers are thecore operational unit of any DSP SoC. This work proposes a LUT based unsignedmultiplication which is proven to be efficient in terms of high operating speed. For n bitinput multiplication n*n memory array of 2 n bit size is required to memorize all thepossible input and output combination. Various literature works claims to be achieve highspeed multiplication with reduced LUT size by integrating a barrel shifter mechanism.This paper work address this problem, by reworking the multiplier architecture with aparallel operating pre-processing unit which used to change the multiplier and multiplicandorder with respect to the number of computational addition and subtraction stages required.Along with LUT multiplier a low power bus encoding scheme is integrated to limit the powerconstraint of the on chip DSP unit. This paper address both the speed and power optimizationtechniques and tested with various FPGA device families.

Inversion of radiative transfer model for retrieval of wheat biophysical parameters from broadband reflectance measurements

This study describes the retrieval of wheat biophysical variables of leaf chlorophyll(Cab),leaf area index(LAI),canopy chlorophyll(CCC),and leaf wetness(Cw)from broadband reflectance data corresponding to IRS LISS-3(Linear Imaging Self Scanner)sensor by inversion of PROSAIL5B canopy radiative transfer model.Reflectance data of wheat crop,grown under different treatments,were measured by hand-held spectroradiometer and later integrated to LISS-3 reflectance using its band-wise relative spectral response function.Three inversion techniques were used and their performance was compared using different statistical parameters and target diagram.The inversion techniques tried were:a look up table with best solution(LUT-I),a look up table with mean of best 10%solutions(LUT-II)and an artificial neural network(ANN).All the techniques could estimate the biophysical variables by capturing variability in their observed values,though accuracy of estimation varied among the three techniques.Target diagram clearly depicted the superiority of LUT-II over the other two approaches indicating that a mean of best 10%solutions is a better strategy while ANN was worst performer showing highest bias for all the parameters.In all the three inversion techniques,the general order of retrieval accuracy was LAI>Cab>CCC>Cw.The range of Cw was very narrow and none of the techniques could estimate variations in it.In most of the cases,the parameters were underestimated by model inversion.The best identified LUT-II technique was then applied to retrieve wheat LAI from IRS LISS-3 satellite image of 5-Feb-2012 in Sheopur district.The comparison with ground observations showed that the RMSE of LAI retrieval was about 0.56,similar to that observed in ground experimentation.The findings of this study may help in refining the protocol for generating operational crop biophysical products from IRS LISS-3 or similar sensors.

A multi-step standard-cell placement algorithm of optimizing timing and congestion behavior

The timing behavior and congestion behavior are two important goals in the performance-driven standard-cell placement. In this paper, we analyze the relationship between the timing and congestion behavior. We bring up a multi-step placement algorithm to reach the two goals. First, the timing-driven placement algorithm is used to find the global optimal solution. In the second step, the algorithm tries to decrease the maximum congestion while not deteriorating the timing behavior. We have implemented our algorithm and tested it with real circuits. The results show that the maximum delay can decrease by 30% in our timing-driven placement and in the second step the maximum congestion will decrease by 10% while the timing behavior is unchanged.