自适应二进制算术编码的动态可重构实现研究

针对H.266/VVC视频编码标准下的上下文自适应二进制算术编码器编码速度慢、资源开销大的问题,面向可重构结构依据算法的内在并行特性优化了编码架构,并基于动态可重构阵列处理器设计实现了CABAC编码器常规编码模式下的并行映射方法,阵列结构能够根据编码输入对优化后的算法进行动态重构,在避免专用硬件编码器较高的资源开销情况下利用软件重构的方法实现熵编码过程,保证编码准确性的同时提高了视频数据流编码效率,为此类运算密集型算法的硬件实现提供了更为灵活高效的参考途径。仿真结果表明,映射实现的编码过程中每个编码周期完成5个二进制序列的编码,平均编码效率达到384.13Mbin/s。基于FPGA的测试结果表明,软件重构方法与专用硬件实现的编码器相比,资源开销降低且编码效率提升5.47%,与同类型可重构视频编码结构相比,编码效率提升7.03%。     

非零速启停的低功耗步进电机控制器研究

为了优化步进电机开环控制性能,对非零速启停的加减速曲线算法及其低功耗硬件逻辑实现进行了研究。针对零速启停的加减速曲线存在控制性能难以充分发挥的问题,提出了一种非零速启停的步进电机线性加减速曲线算法,将加减速过程划分为四种转动模式,可构建任意的线性速度剖面。首先理论推导了四种加减速转动模式的控制脉冲周期;其次结合流水线设计思想优化加减速曲线算法的硬件逻辑模型,在FPGA中设计了步进电机控制器IP核,并采用门控时钟等低功耗IC设计技术实现了IP核的低功耗;最后,搭建了实验平台进行验证。实验结果表明,IP核可以实现四种转动模式的非零速启停控制,实现了高实时、高精度驱动,提升了20%的控制性能,电路面积优化约30%,功耗降低53%,验证了方案的可行性与有效性。     

基于循环自相关的NC-OFDM信号参数的盲估计

在认知无线电(CR)环境中,频率资源不足的问题越来越严重,非连续正交频分复用（NC-OFDM）能够工作在非连续的频谱环境,针对NC-OFDM信号的参数估计重要问题,提出用循环自相关的方法。该方法首先分析循环平稳信号特点,然后根据NC-OFDM信号的循环自相关在循环频率α以及时延τ切面图具有离散谱线特征进行参数估计,最后对NC-OFDM信号的循环自相关进行数值仿真。仿真结果表明在低信噪比下,能有效估计NC-OFDM信号的参数及识别零前缀的正交频分复用信号（ZP-OFDM）,且实验证明关闭近90%的子载波数目,都能够实现NC-OFDM信号的参数的盲估计。     

Application of orthogonal collocations to some transport phenomena problems in co-axial cylinders and spheres

Collocation methods are developed for the solution of some differential equation models for transport phenomena problems in one-and two-dimensions in co-axial annuli of spherical and cylindrical shapes. General formulae are developed to obtain orthogonal polynomials over an arbitrary interval using two types of weighting functions. The convergence and accuracy of the methods are demonstrated using two test problems, i.e., calculation of effectiveness factors in (a) a spherical pellet with peripherally deposited catalyst and (b) a Raschig ring type cylindrical catalyst pellet. Comparisons of results obtained from the present methods with analytic solutions for the first-order reactions indicate good agreement. Numerical solutions are also obtained for the second-and the third-order reactions for which analytic solutions are not available. Results obtained in terms of a new Thiele modulus involving the ratio of volume of peripherally deposited part of catalyst to exterior surface area indicate that this normalization brings effectiveness factor versus Thiele modulus curves close together for co-axial spherical and long cylindrical pellets, as it does for these geometries without the inner co-axial portion.     

三维纺织结构增强复合材料的几何模型

基于对织物断面显微照片的观察和分析，首先建立了三维正交织物的单元结构模型，并以此为基础建立了正交接结织物的单元结构模型；利用几何模型公式推导建立几何结构特征参数与编织工艺参数之间的理论关系；在此基础上计算了纱线长度、接结经与经纱的取向角和纤维体积含量；通过几何极限条件定义了织物紧度，为进一步研究其力学性能奠定基础。     

An immune orthogonal learning particle swarm optimisation algorithm for routing recovery of wireless sensor networks with mobile sink

The growth of mobile handheld devices promotes sink mobility in an increasing number of wireless sensor networks (WSNs) applications. The movement of the sink may lead to the breakage of existing routes of WSNs, thus the routing recovery problem is a critical challenge. In order to maintain the available route from each source node to the sink, we propose an immune orthogonal learning particle swarm optimisation algorithm (IOLPSOA) to provide fast routing recovery from path failure due to the sink movement, and construct the efficient alternative path to repair the route. Due to its efficient bio-heuristic routing recovery mechanism in the algorithm, the orthogonal learning strategy can guide particles to fly on better directions by constructing a much promising and efficient exemplar, and the immune mechanism can maintain the diversity of the particles. We discuss the implementation of the IOLPSOA-based routing protocol and present the performance evaluation through several simulation experiments. The results demonstrate that the IOLPSOA-based protocol outperforms the other three protocols, which can efficiently repair the routing topology changed by the sink movement, reduce the communication overhead and prolong the lifetime of WSNs with mobile sink.     

化工搅拌器的参数优选

本文提出了确定化工用搅拌器搅拌时间的一种简单试验方法,并用正交表安排寻找最佳搅拌参数的试验和整理试验数据,得到了有实用价值的结果。     

γ-Al2O3载体制备中水洗脱氯工艺的连续化

通过正交实验，研究了γ-Al₂O₃载体制备中拟薄水铝石水洗的连续化。方差分析表明，第一阶段洗水的pH是影响脱氯效果的关键因素，初步得出水洗连续化的优化条件。与国内外传统的间歇式水洗相比，收率从80%提高到99.7%，所需洗水量仅为原来的1/3，而处理500 kg物料的生产周期也从10 h缩短到2～3 h。     

一种聚羧酸型高效减水剂的试验研究

采用溶液共聚合成了一种聚羧酸型高效减水剂,对合成中影响减水剂性能的各种因素进行了分析;运用正交实验法,得出了合成该减水剂最佳配方和工艺条件;并研究了该减水剂对水泥净浆性能和混凝土性能的影响。结果表明,该产品掺量少(1.2%)、分散性能好(减水率25.4%)、混凝土性能高(抗压强度比178%)、不含甲醛等有害物,是一种良好的混凝土减水剂。     

Pattern synthesis of time‐modulated conformal arrays by an improved differential evolution algorithm

In this article, an improved differential evolution algorithm (IDE) based on two different colonies is proposed and applied to time‐modulated conformal arrays syntheses. The whole population of IDE is divided into two parts. The one part searches the solution globally while the other searches the neighborhood of the solution provided by the previous one. Benchmark functions are provided to testify IDE. Furthermore, IDE is applied to synthetize sum‐difference patterns with a 1 × 16 elements time‐modulated circular array and low sidelobe level (SLL) patterns with an 8 × 12 elements time‐modulated cone array. After optimization, the sideband level (SBL) of the circular array at the first sideband frequency is ?1.00 dB. The SLL and SBL at the first sideband frequency of the cone array are lower than ?30.00 and ?20.00 dB, respectively. Experiment results verify the superior performance of IDE. Moreover, to accelerate the computation speed, graphics processing unit parallel computing technique is introduced into pattern synthesis and the acceleration ratios of more than 23 times can be achieved. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:697–705, 2014.