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。     

线形超声相控阵换能器的阵列设计

超声相控阵检测技术是利用脉冲反射法对被检构件中是否存在缺陷(如裂纹、夹杂、气孔等)进行无损检测,阵列换能器是该检测技术中实现电-声转换的传感器件,其声场特性是能否获得并有效利用被检测部位或区域回波信息的决定因素,也是设计换能器阵的主要依据。从平面矩形活塞阵元的辐射声场出发,利用简便算法对阵元辐射声场、一维线阵辐射声场进行了仿真模拟,分析了影响阵列换能器性能的几个主要因素,提供了阵列换能器的设计思路,并对采用相控阵超声换能器与常规超声换能器探测人工缺陷时的扫查波形进行了比较。     

用于麦克风阵列的阵元筛选方法研究

在使用TDOA算法进行被动声定向时,为精确获取麦克风阵列阵元之间接收声源信号的时间差,进而计算目标的方位角,麦克风阵元之间必须保持较高的相位一致性。而从论文与专利检索来看,目前还没有有效方法筛选出符合要求的麦克风阵元。针对此问题,本文基于麦克风阵列阵元相位一致性的指标,设计出麦克风阵元筛选系统,通过实测数据分析表明:一致性较高的麦克风更适合组建麦克风阵列。     

新的设计模式——数组工厂和数组原型模式

为了去除程序中的简单开关分支结构,提出了一种新的重构方法——"以数组取代类型码"重构手法。将这种新的重构方法用于重构简单工厂模式,就得到了一种新的软件设计模式——"数组工厂"模式。数组工厂模式适用于实例化某个具体类在软件执行流程的任意时刻只存在一个实体的对象;对于软件执行流程中可以同时存在多个实体的具体类对象的实例化工作,通过改造数组工厂模式,提出了"数组原型"模式。数组工厂和数组原型模式是两种结构优良的创建型设计模式,它们免除了简单工厂方法中的开关分支语句,具有优化代码结构、提高程序执行性能等优点,并且完全符合开放—封闭原则。     

Self-organizing learning array

A new machine learning concept-self-organizing learning array (SOLAR)-is presented. It is a sparsely connected, information theory-based learning machine, with a multilayer structure. It has reconfigurable processing units (neurons) and an evolvable system structure, which makes it an adaptive classification system for a variety of machine learning problems. Its multilayer structure can handle complex problems. Based on the entropy estimation, information theory-based learning is performed locally at each neuron. Neural parameters and connections that correspond to minimum entropy are adaptively set for each neuron. By choosing connections for each neuron, the system sets up its wiring and completes its self-organization. SOLAR classifies input data based on the weighted statistical information from all the neurons. The system classification ability has been simulated and experiments were conducted using test-bench data. Results show a very good performance compared to other classification methods. An important advantage of this structure is its scalability to a large system and ease of hardware implementation on regular arrays of cells.     

Scheduling block-cyclic array redistribution

This article is devoted to the run-time redistribution of one-dimensional arrays that are distributed in a block-cyclic fashion over a processor grid. While previous studies have concentrated on efficiently generating the communication messages to be exchanged by the processors involved in the redistribution, we focus on the scheduling of those messages: how to organize the message exchanges into “structured” communication steps that minimize contention. We build upon results of Walker and Otto, who solved a particular instance of the problem, and we derive an optimal scheduling for the most general case, namely, moving from a CYCLIC(r) distribution on a P-processor grid to a CYCLIC(s) distribution on a Q-processor grid, for arbitrary values of the redistribution parameters P, Q, r, and s     

Practically efficient array initialization

Initialization of an array, out of which only a small initially unknown portion will eventually be used, is a frequent need in programming. A folklore solution for initializing an array of n entries in constant time uses 2n?log2n? extra bits to realize a stack of back pointers to the actually used entries of the array. Navarro has given a succinct version of this technique, which requires only n + o(n) bits of auxiliary storage. We describe, analyze, and experimentally compare these solutions and their space‐efficient but theoretically suboptimal alternatives based on a simple bitmap for keeping track of the array entries which have been assigned a value. Experimental results suggest that each of the methods has its niche of excellence, which are roughly as follows: the theoretically optimal solutions based on a stack of back pointers perform in general best on sparse arrays, whose access frequency is less than 1% of the number of their entries. Brute‐force initialization of the entire array seems generally to give the best overall performance for dense arrays whose access frequency is over 10% of their size. For the remaining cases of arrays with 1–10% access frequency, the methods which use a simple bitmap appear to give the best performance. The experiments show that the choice of a suitable implementation may yield substantial, up to hundreds of times speed‐ups in the performance of initializable array operations. Copyright © 2015 John Wiley & Sons Ltd.     

Selective substitution array grammars

Selective substitution array grammars are introduced, which abstract the notions of rewriting rules, direct derivation steps, derivations and rewriting in a sequential or parallel way. These array grammars provide for a unified framework for many of the two-dimensional array grammars in the literature. In addition, they point towards new interpretations resulting in possible new array grammars.     

The mapping of 2-D array processors to 1-D array processors

We consider the case of a 2-dimensional wavefront array processor where only one wavefront appears at any time. We show that in such a situation, this 2-dimensional wavefront processor can be mapped to a linear array processor if the wavefronts never backtrack. The mapping will not increase the number of registers in each processor element. Two examples, the spoken words recognition problem and the longest common subsequence problem, are given to demonstrate the feasibility of this method.     

准最佳三进阵列偶

最佳二进阵列在通信领域中有着广泛的应用,但由于其存在体积的限制,制约了它的应用范围,针对这种现象,提出了一种新的最佳离散信号,即准最佳三进阵列偶,给出了准最佳三阵列偶的定义和变换性质,研究了它的组合允许条件,分析了它与准最佳二进阵列偶、准最佳屏蔽二进阵列偶以及最佳三进阵列偶之间的关系,并用计算机搜索出部分小体积的准最佳三进阵列偶。实验结果显示准最佳三进阵列偶的存在范围非常广泛,为通信工程的应用提供了更多的选择。     

Pyroelectric thin-film sensor array

Pyroelectric thin-film point detectors and 1 × 12 arrays have been fabricated and characterized. They consist of sol-gel-deposited PZT thin-film elements on micromachined Si₃N₄/SiO₂ membranes. The measured current and voltage response as a function of modulation frequency of a 1 × 12 array element is compared with finite-element calculations. Voltage responsivities of almost 3000 V W⁻¹ in vacuum and 800 V W⁻¹ in air have been achieved for 0.4 mm × 0.9 mm elements. Some point detectors have been completely packaged and correct operation in a movement detection system has been demonstrated.     

Fine-grained multi-phase array designs

Hybrid multiprocessor architectures which combine re-configurable computing and multiprocessors on a chip are being proposed to transcend the performance of standard multi-core parallel systems. Both fine-grained and coarse-grained parallel algorithm implementations are feasible in such hybrid frameworks.     

Vertical comb array microactuators

A vertical actuator fabricated using a trench-refilled-with-polysilicon (TRiPs) process technology and employing an array of vertical oriented comb electrodes is presented. This actuator structure provides a linear drive to deflection characteristic and a large throw capability which are key features in many sensors, actuators and micromechanisms. The actuation principle and relevant theory is developed, including FastCap simulations for theoretical verification. Design simplifications have been suggested that enable one to use parallel plate analytical expressions which match simulation results with /spl sim/5.6% error. Several actuators were designed and fabricated using the 7-mask TRiPs technology with calculated drive voltages as low as 45 V producing 10 /spl mu/m of deflection. The actuators employed a mechanical structure that was 18 /spl mu/m tall using a polysilicon layer 1.5 /spl mu/m thick and occupying a total area of 750 /spl mu/m by 750 /spl mu/m. The actuators were successfully tested electrostatically and several microns of deflection were observed.     

Shrink-induced single-cell plastic microwell array

The ability to interrogate and track single cells over time in a high-throughput format would provide critical information for fundamental biological understanding of processes and for various applications, including drug screening and toxicology. We have developed an ultrarapid and simple method to create single-cell wells of controllable diameter and depth with commodity shrink-wrap film and tape. Using a programmable CO(2) laser, we cut hole arrays into the tape. The tape then serves as a shadow mask to selectively etch wells into commodity shrink-wrap film by O(2) plasma. When the shrink-wrap film retracts upon briefly heating, high-aspect plastic microwell arrays with diameters down to 20 μm are readily achieved. We calibrated the loading procedure with fluorescent microbeads. Finally, we demonstrate the utility of the wells by loading fluorescently labeled single human embryonic stem cells into the wells.