互耦效应下端射阵机载雷达空时内插STAP方法

针对端射阵天线由于阵元间距较小,容易造成能量耦合引起互耦效应,进而影响天线增益和空域导向矢量等参数以及后续的杂波抑制性能这一问题,首先利用互阻抗法和等距离环地面散射单元积分法,建立了互耦条件下的端射阵机载雷达信号模型;然后分析了互耦效应对杂波特征谱和空域导向矢量等参数的影响;最后提出了一种基于空时内插的空时自适应处理方法,对杂波的非平稳性和空域导向矢量进行了补偿.理论分析和仿真结果证明了该方法的有效性.     

基于FPGA的硬圆弧插补器设计

基于PC的数控系统成为开放式数控系统发展的必然趋势，其中PC加控制板卡的结构为实际的开放式标准体系。本文采用FPGA器件实现了扩展DDA圆弧插补算法，在满足较高精度的情况下，具有较快的插补速度，而且容易与电机的运动控制部分很好的信成，制作成控制板卡，从而适应目前基于PC加控制板卡的开放式数控系统的发展趋势。     

DECOUPLER DESIGN AND CONTROL SYSTEM TUNING BY INA FOR DISTILLATION COMPOSITION CONTROL†

Six distillation column models have been used in studies of the usefulness of the Inverse Nyquist Array (INA) method for design of dual composition control for distillation. Five of the column models are experimental, one describing an industrial column, the others four pilot plants. One column model is obtained by modeling from first principles.

The control strategies investigated and compared are multiloop SISO, 2-way decoupling and l-way decoupling. The control variables are the standard ones, i.e. reflux flow and boilup.

In most of the cases INA has been found to be a useful tool for design of the loops and for comparison of the different control approaches. INA has also been found to be useful for simultaneous tuning of the decouplers and the feedback controllers.

For 2-way decoupling the criterion to minimize interaction at the critical frequency for each primary feedback loop has been found useful in most, but not all, cases. The scheme can be designed by pure gains in the decouplers and there is no reason to introduce dynamics into the decouplers—the systems studied are already sufficiently rich in dynamics.

INA has been found to be a suitable vehicle for the choice between the two possible l-way decoupling schemes.

With the design approach taken, l-way decoupling has been found to provide considerably better control quality than 2-way decoupling in two of the six systems, the differences in control quality being small in the other cases.

The effect of model mismatching on the results, caused e.g. by process nonlinearities, is discussed and simple rules to decrease the parameter sensitivity for 2-way decoupling schemes are given. When model mismatching is considered, the advantage of l-way decoupling over 2-way decoupling seems to increase.

One deficiency of the INA design as used in this paper is that it does not single out the design which is to be preferred on the grounds of robustness.     

提升管-下行床耦合反应器模拟

采用轴径向二维扩散模型对提升管-下行床耦合反应器催化裂化反应进行了数学模拟,并与提升管及下行床进行了对比.结果表明,在下行床之前耦合一段适当长度的提升管不仅可以保证原料具有较高的转化率,而且可以保证目的产品的选择性较高,缩短达到相同产品收率所需的下行床长度.这种耦合反应器充分利用了提升管与下行床各自的优势,并可以根据具体的原料及产品需求调整进料的位置以改变提升段与下行段的长度比例,实现柔性操作.     

相控阵雷达天线阵面记录回放系统

相控阵雷达广泛应用,其天线阵面对记录回放系统的数据速率要求提升。针对两种传统记录回放系统架构的不足,结合其优点,设计并实现了一种新型的基于FPGA的记录回放系统。该系统设计为板卡的形式,FPGA实现对硬盘的读写操作,采用自定义的文件系统对数据进行管理。经过测试,系统记录速度可以达到292 MB/s,回放速率为340 MB/s。实验结果表明,该记录回放系统性能稳定,通用性好,存储速率满足要求。     

水声传感阵列指向性与系统传输性能研究

针对浅海水声通信中水汽界面和海底的反射产生多途效应对信号传输的影响,依据水下声传输原理,分析了水声信道中的噪声特点和产生多途效应机理,研究水声信道中声传感器指向性与传输性能关系,探讨水声传感阵列方式在水下通信环境的优势,设计合理的阵元间连接形式、阵列驱动电路和阻抗匹配电路,保证有效的功率耦合效率。经水下试验测试表明:采用一定指向性的声阵列结构,利用单个阵元波束宽度小于10°,构成阵列结构的波束宽度小于30°,并进行一定阻抗匹配,可减小能量损失,有效提高水声通信系统性能。     

Kokkos: Enabling manycore performance portability through polymorphic memory access patterns

The manycore revolution can be characterized by increasing thread counts, decreasing memory per thread, and diversity of continually evolving manycore architectures. High performance computing (HPC) applications and libraries must exploit increasingly finer levels of parallelism within their codes to sustain scalability on these devices. A major obstacle to performance portability is the diverse and conflicting set of constraints on memory access patterns across devices. Contemporary portable programming models address manycore parallelism (e.g., OpenMP, OpenACC, OpenCL) but fail to address memory access patterns. The Kokkos C++ library enables applications and domain libraries to achieve performance portability on diverse manycore architectures by unifying abstractions for both fine-grain data parallelism and memory access patterns. In this paper we describe Kokkos’ abstractions, summarize its application programmer interface (API), present performance results for unit-test kernels and mini-applications, and outline an incremental strategy for migrating legacy C++ codes to Kokkos. The Kokkos library is under active research and development to incorporate capabilities from new generations of manycore architectures, and to address a growing list of applications and domain libraries.     

迭代全息搜索策略及其在动力学参数估计中的应用

针对反应动力学参数估计的复杂性,设计了一种新颖的优化方法-迭代全息搜索策略(IHRS).全息搜索策略(HRS)将多维空间中的寻优问题直观地通过二维全息图上的近邻搜索来实现,是一种全局搜优效率较高的确定性优化方法,但它只能用于离散系统的优化.IHRS通过对连续变量进行离散化处理,并运用迭代计算逐步缩小离散系统与原连续系统的偏差,将复杂的多维连续变量优化问题转化为多个串联的较为简单的离散变量组合优化问题,再运用HRS寻优.并讨论了等分区间数、搜索域收缩率、群规模等参数对IHRS搜优效率的影响.六维Alpine函数测试表明,IHRS的全局优化性能优于单纯形法和遗传算法(GA).将IHRS应用于SO2催化氧化反应动力学模型参数的估计,取得了满意的结果.     

二维多层次的云服务可靠性评估方法研究

针对云服务业务流程管理的特点, 给出了云服务的组合实现框架; 依据随机Petri网的建模理论, 探讨了组合云服务流程网模型的细粒度建模方法; 根据动态多变的用户需求, 设计了二维多层次的云服务组合可靠性动态评估框架, 并给出了马尔可夫过程和等值约简的两种可靠性计算方法。应用示例分析结果表明, 该方法具有较好的动态适应性和灵活性, 能有效满足云服务的可靠性评估需求。