信号采集与数据处理电路的研究

随着原子核科学技术的发展，无论是对原子核内部特征和规律的研究，或者是对原子核科学技术的应用，都需要对核辐射和原子核所携带的信息进行测量和分析研究。在核电子学测量系统中，核辐射探测器输出信号在经过各种信号处理电路后，通常都要变换成数字信号，再经过数据收集和处理，给出实验的最终结果，因此实验工作的任何进展都要求有相应的数据获取和处理系统的支持。根据实验的实际需求，我们以采集、处理探测器输出的信号为题，开展了一些研究工作，我们先后开展的研究工作包括以下儿个方面：1．激光功率计的变换与显示电路的研制2．基于PCI总线、嵌入8051单片机的计数卡的研制3．数据处理分析软件的设计这三部分的设计工作我们将在论文的第二、第三、第四章分别进行阐述。激光功率计的变换与显示电路把由激光功率计输出的模拟电压量变为数字脉冲输出，并且把该输出脉冲的频率实时定性显示出来。本电路测量精度高，线性好，工作稳定。我们研制开发的计数卡是一种很实用的计数卡，它是一种基于PCI总线，嵌入单片机的高速计数器，最大计数范围为109-1，最高的计数频率为20MHz。该计数卡计数范围宽，计数频率高，具有定时计数、重复计数等功能，可以取代常规的定标器，具有广泛的应用前景。数据处理分析软件包括下位机软件、上位机软件及通讯协议三部分，实现数据的采集与记录，并将读取的数据以Excel电子表格的形式存储，以备查询。下位机的软件采用KeilC编写，上位机软件采用Delphi编写。目前激光功率计的变换与显示电路和计数卡及相应的数据处理软件都设计、调试完成，已经投入使用，获得满意结果，受到好评。

黄土丘陵区纸坊沟流域农业生态安全预警分析

为黄土丘陵区生态安全预警及其建设提供科学依据。【方法】以纸坊沟流域近70年代表年份生态安全态势及影响因子的分析为基础,参考压力-状态-响应(PSR)模型建立农业生态安全预警指标体系。运用层次分析法(AHP)和德尔菲法(Delphi)确定指标权重,采用综合指数法计算生态安全质量值,用演化轴解释生态安全预警模式,定量评价该流域1938~2005年的农业生态安全状况,并预测2015年的发展趋势。【结果】纸坊沟流域1938年处于蓝灯区,无需预警;1958年为黑灯区,需作生态安全恶化速度预警;1975和1985年处于红灯区,需作生态安全较差状态预警;1995年处于黄灯区,2005和2015年继续向良好方向演化,均不需预警,但从发展趋势来看,预计人口密度于2020年左右进入警戒状态。【结论】研究结果与该流域的实际情况相符,该指标体系和生态安全预警模型可以应用于黄土丘陵区。

井间地震速度层析成像方法与软件系统

Crosshole Seismic tomography has been broadly studied and applied in the fields of resource exploration and engineering exploration because of its special observing manner and better resolution than normal seismic exploration. This thesis will state the theory and method of Crosshole Seismic tomography. Basing on the previous studies，the thesis studied the initial velocity model，ray-tracing method, and developed the three-dimension tomography software. All the cells that a ray passes through are of the same velocities if the paths from transmitters to receivers are straight. The cells that the each ray passes through are recorded, and rays that pass through each cell are calculated. The ray average velocity which passes through a cell is set as the cell velocity. Analogously we can make a initial node velocity model because the velocity sum is calculated on the all cells which own to a certain node, and the cell number is summed about each nodes，the ratio of the velocity sum to the all cells number is set as the node velocity. The inversion result from the initial node velocity model is better than that of the average velocity model. Ray-bending and Shortest Path for Rays (SPR) have shortcomings and limitations respectively. Using crooked rays obtained from SPR rather than straight lines as the starting point can not only avoid ray bending converging to the local minimum travel time path, but also settle the no smooth ray problem obtained by SPR. The hybrid method costs much computation time, which is roughly equal to the time that SPR expends. The Delphi development tool based on the Object Pascal language standard has an advantage of object-oriented. TDTOM (Three Dimensions Tomography) was developed by using Delphi from the DOS version. Improvement on the part of inversion was made, which bring faster convergence velocity. TDTOM can be used to do velocity tomography from the first arrival travel time of the seismic wave, and it has the good qualities of friendly user interface and convenient operation. TDTOM is used to reconstruct the velocity image for a set of crosshole data from Karamay Oil Field. The geological explanation is then given by comparing the inversion effects of different ray-tracing methods. High velocity zones mean the cover of oil reservoir, and low velocity zones correspond to the reservoir or the steam flooding layer.