硅微阵列陀螺仪闭环驱动控制技术研究

为了进一步提高硅微阵列陀螺仪驱动模态的控制精度与稳定性,深入分析了硅微阵列陀螺仪的结构设计和闭环驱动控制技术。基于硅微阵列陀螺仪闭环驱动控制的特点,以现场可编程门阵列(FPGA)为核心控制平台,实现一种基于自激振荡原理的数字化闭环驱动电路。分析并建立了自激振荡与幅度控制的基本模型,基于Simulink实现了闭环自激驱动的仿真。实验结果表明,常温下驱动幅度控制精度达到9×10~(-5),并能有效跟踪驱动模态谐振频率。     

阵列式多针-柱电极装置实现离子风的实验与分析

为了实现一定气体流速的离子风,设计了一种新型的阵列式三排3 ×3垂直放置的针-柱电极结构放电装置.在针-柱之间间距为3mm、排与排之间间距为8 mm、镇流电阻12 MΩ、放电电阻12 MΩ、测试电阻1 kΩ、大气压环境、室温、无外部通入气流时,阵列式针-柱电极实现了稳定的电晕放电,并通过示波器记录的放电波形、数码相机拍摄的发光图像以及放电伏安特性曲线进行了验证.同时,随着阵列式排数的增加,放电电流变大,离子风风速也随之增大.该针-柱结构易于用MEMS工艺加工制作,可应用于便携式分析仪器中.     

基于射频隐身的相控阵雷达搜索控制参量优化设计

机载雷达射频隐身技术对提高飞行器生存能力具有重要意义。 本文研究了机载相控阵雷达基于射频隐身的搜索控制参量优化设计。通过分析截获概率原理 ,给出了目标特征和雷达系统性能对驻留时间和波位间隔等搜索控制参量的影响关系,构建 了目标探测性能与隐身性能约束下的优化模型。仿真获得了满足隐身要求下相控阵雷达的最 优搜索控制参数。     

旅行商问题中巡回路径的数据结构

旅行商问题中巡回路径的数据结构对局部启发式算法的效率起着非常关键的作用。巡回路径的数据结构必须能够查询一条回路中每个城市的相对顺序,并且能够将一条回路中的部分城市逆序。分析了数组表示法、伸展树表示法和两级树表示法表示巡回路径时各种基本操作的实现过程及时间复杂度。数组表示法能够在常数时间内确定一条回路中每个城市的相对顺序,但是最坏情况下完成逆序操作需要Ω（n）时间,不适用于大规模的旅行商问题。伸展树表示法执行查询和更新操作的平摊时间复杂度是O（logn）,适用于极大规模的旅行商问题。而两级树表示法在最坏情况下每一个更新操作的时间复杂度是O（n^0.5）,适用于大规模的旅行商问题。     

Self-aligned fabrication of single crystal diamond gated field emitter array

This paper describes a self-aligned fabrication process for diamond gated field emitter array (FEA). Utilizing the non-conformal coverage sputtering conditions of silicon oxide, an interesting “sphere on cone” structure is formed on diamond nano tip array, which is the key point of gate hole opening process. This structure causes shadowing at certain regions of side-wall during Ti / Au gate metal deposition. Removal of “sphere” by wet etching leads to the successful fabrication of a single crystalline diamond gated FEA. Scanning electron microscope observations reveal the fabrication of a uniform emitter array with tip radius of curvature (20 nm) and gate hole (1.4 μm). We also confirmed that no noticeable physical damage exists on tip. In field emission characteristics of the fabricated single crystal diamond gated FEA, gate voltage control of field emission current is realized.     

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。     

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.     

Synthesis of antenna arrays with an efficient multiobjective differential evolution algorithm

An efficient multiobjective differential evolution algorithm for array synthesis is proposed in this article. By introducing novel strategies in the generalized differential evolution (GDE3), the proposed algorithm can generate a better converged and distributed Pareto front than the standard GDE3. Five typical benchmark functions are optimized by the proposed improved GDE3 (IGDE) to verify its effectiveness. Furthermore, the proposed algorithm is applied in two‐pattern synthesis problems, including an unequal spaced linear array and a conformal array. The superior performance of the proposed IGDE demonstrates that it is an efficient and competitive algorithm in the function optimization, pattern synthesis, and other electromagnetic problems. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:161–169, 2014.     

Preparation of phenolic resin derived 3-D ordered macroporous carbon

Three-dimensionally ordered long-range macroporous carbon structures were prepared using commercially available phenolic resin by utilizing sacrificial colloidal silica crystalline arrays as templates that were subsequently removed by HF etching after pyrolysis in an argon atmosphere. SEM, TEM, and BET were employed to characterize the morphology and the surface area of the porous carbon structures. The pore size (150–1000 nm) and BET surface area, which reflect pore volume (298.6 m²/g (1.32 cm³/g) ∼ 93.7 m²/g (0.12 cm³/g)), of the macroporous carbon structures produced were approximately proportional to the size (150–1000 nm) of the sacrificial silica sphere templates used (annealing temp. 550°C). The achieved 550 nm porous carbon structures were examined to function as potential catalyst carriers and were successfully impregnated with Ag or Pt-Ru on their inner walls after borohydride reduction at room temperature. In addition, porous carbon patterns were fabricated using the ‘micromolding in capillary’ technique, which has potential applications in the microreaction technology.