Two-step digit-set-restricted modified signed-digit addition-subtraction algorithm and its optoelectronic implementation

A novel, to our knowledge, two-step digit-set-restricted modified signed-digit (MSD) addition-subtraction algorithm is proposed. With the introduction of the reference digits, the operand words are mapped into an intermediate carry word with all digits restricted to the set {1 , 0} and an intermediate sum word with all digits restricted to the set {0, 1}, which can be summed to form the final result without carry generation. The operation can be performed in parallel by use of binary logic. An optical system that utilizes an electron-trapping device is suggested for accomplishing the required binary logic operations. By programming of the illumination of data arrays, any complex logic operations of multiple variables can be realized without additional temporal latency of the intermediate results. This technique has a high space-bandwidth product and signal-to-noise ratio. The main structure can be stacked to construct a compact optoelectronic MSD adder-subtracter.     

Quantum dot-based local field imaging reveals plasmon-based interferometric logic in silver nanowire networks

We show that the local electric field distribution of propagating plasmons along silver nanowires can be imaged by coating the nanowires with a layer of quantum dots, held off the surface of the nanowire by a nanoscale dielectric spacer layer. In simple networks of silver nanowires with two optical inputs, control of the optical polarization and phase of the input fields directs the guided waves to a specific nanowire output. The QD-luminescent images of these structures reveal that a complete family of phase-dependent, interferometric logic functions can be performed on these simple networks. These results show the potential for plasmonic waveguides to support compact interferometric logic operations.     

All-optical method for the addition of binary data by nonlinear materials

An all-optical system for the addition of binary numbers is proposed in which input binary digits are encoded by appropriate cells in two different planes and output binary digits are expressed as the presence (=1) or the absence (=0) of a light signal. The intensity-based optical XOR and AND logic operations are used here as basic building blocks. Nonlinear materials, appropriate cells (pixels), and other conventional optics are utilized in this system.     

Magnetic bubble logic

Although the literature on the bubble logic devices is limited, the concepts and device configurations are diverse. In conductor-access devices, logic can be performed by bubble transfer operations. In field-access devices, logic can be performed by providing alternative paths which are selected by interaction between bubbles. Examples include the conjugate logic gates, the resident-bubble cellular logic, and the chevron 3-3 circuits. Logic can also be performed by counting bubbles, such as in the symmetric switching function implementation. The various mechanisms for implementing bubble logic are all described by truth tables. To assess their efficiency, they are compared in terms of space and delay when they are used to implement the same logic element - a full adder. They are all comparable except for the resident-bubble cellular logic which requires excessive space and delay. However, it is important to point out that only the symmetric switching function devices offer rewrite-ability to eliminate the part number problem, and accommodation for a large number of inputs to ease interconnection and delay equalization problems.     

Neural network that incorporates direct optical imaging

A compact neural network architecture is described that can be trained to sense and classify an optical image directly projected onto it. The system is based on the combination of a two-dimensional amorphous silicon photoconductor array and a liquid-crystal spatial light modulator. Appropriate filtering of the incident optical image on capture is incorporated into the network training rules through a modification of the standard backpropagation training algorithm. Training of the network on two image-classification problems is described: the recognition of handprinted digits and facial recognition. The network, once trained, is capable of stand-alone operation, sensing an incident image, and outputting a final classification signal in real time.     

基于图像处理技术的天然气表检测

针对传统天然气检测系统存在的检测效率低和准确性不高的问题,提出了基于显著形状特征的天然气表数字图像识别方法,通过对数字外轮廓进行简洁、高效的编码,并辅助数字长宽比、内腔等其他形状特征,从而能同时识别整字和半字出现的情况,即而实现了气表检测过程中读数的自动化。实践证明,新系统的检测效率大为提高。     

Parallel optical negabinary arithmetic based on logic operations

On the basis of signed-digit negabinary representation, parallel two-step addition and one-step subtraction can be performed for arbitrary-length negabinary operands. The arithmetic is realized by signed logic operations and optically implemented by spatial encoding and decoding techniques. The proposed algorithm and optical system are simple, reliable, and practicable, and they have the property of parallel processing of two-dimensional data. This leads to an efficient design for the optical arithmetic and logic unit.     

Musing on Use and Misuse of Numerical Data of Quantities in Measurement Science

Measurement Techniques - The empirical numerical value of a quantity is not a number that can be treated as a simple mathematical object. The digits are not only determined by the chosen reference,...     

Optoelectronic butterfly interconnection architecture of modified signed-digit arithmetic systems: fully parallel adder and subtracter

The carry-free property of modified signed-digit addition is discussed, and a space-position-logic-encoding scheme is proposed, which not only makes best use of the convenience of binary (0, 1) logic operation but is also suitable for the trinary (1, 0, 1-) property of modified signed-digit digits. Based on the spaceposition-logic-encoding scheme, a fully parallel modified signed-digit adder and subtracter is built by use of optoelectronic switch modules and butterfly interconnections; thus an effective combination of a parallel algorithm and a parallel architecture is implemented. The effectiveness of this architecture is verified by both simulation and experimental results.     

Logic functions for magnetic bubble devices

An analysis has been made of the number and types of logical functions which can be performed using the interaction of circular magnetic domains in rare earth iron oxides. Multiple logic functions are found to be produced simultaneously at any logical area. These conjunctive output sets have been categorized. Several conjunctive logic gates have been designed, fabricated, and tested successfully in Sm0.55Tb0.45FeO3using Permalloy overlays. Utilizing a circuit in which AND/OR logic gates are coupled to a dynamic memory bank, the total correlation of two data streams has been performed. It is shown how this multiply accessed dynamic memory serves to establish the correlation threshold.     

A Josephson ternary associative memory cell

The authors describe a three-valued content-addressable memory cell using a Josephson complementary ternary logic (JCTL) circuit. The memory cell can perform the operations of searching, writing and reading in the ternary logic system. The principle of the memory circuit is illustrated in detail by using the threshold characteristics of the JCTL. Computer simulations were performed to investigate how high-performance operation can be achieved. Simulation results show that the cycle time of memory operation is 120 ps, power consumption is about 0.5 μW/cell, and tolerances of writing and reading operation are ±15% and ±24% respectively     

一类带有未知控制方向的非线性系统的模糊自适应事件触发容错控制

针对带有未知控制方向、未知非线性函数以及执行器故障的不确定非线性系统,研究了相应的模糊自适应事件触发容错控制问题。首先,运用反步法和模糊逻辑系统 (FLS) 理论知识相结合,构造出自适应事件触发容错控制器和自适应更新律,有效地补偿了执行器故障对系统的影响。其次,在自适应事件触发容错控制器的设计中引入了 Nussbaum 函数。最后,所设计的控制方案保证了闭环信号在给定紧集内一致最终有界,且仿真结果验证了本文所提出的控制方案的有效性。     

Classification and recognition of handwritten digits by using mathematical morphology

The present paper proposes a novel algorithm for recognition of handwritten digits. For this, the present paper classified the digits into two groups: one group consists of blobs with/without stems and the other digits with stems only. The blobs are identified based on a new concept called morphological region filling methods. This eliminates the problem of finding the size of blobs and their structuring elements. The digits with blobs and stems are identified by a new concept called ‘connected component’. This method completely eliminates the complex process of recognition of horizontal or vertical lines and the property called ‘concavities’. The digits with only stems are recognized, by extending stems into blobs by using connected component approach of morphology. The present method has been applied and tested with various handwritten digits from modified NIST (National Institute of Standards and Technology) handwritten digit database (MNIST), and the success rate has been given. The present method is also compared with various existing methods.     

热复合磁脉冲粉末压坯致密度的试验研究

对加热Cu粉末进行磁脉冲致密试验研究,探索提高压坯致密度且不使粉末颗粒产生明显长大的致密方法.通过压坯平均致密度和微观金相形貌分析,揭示了加热温度、放电参数和粉末体高径比等工艺参数对Cu粉末热复合磁脉冲致密压坯致密度的影响规律.研究表明:压坯致密度不随温度升高而线性增加,200℃时的致密度最高;在给定放电能量和200℃下,压坯的致密度随电压和电容量增加而提高,随粉末质量增加而降低;3次放电显著改善压坯致密效果,致密度达98.75%,再增加次数的影响甚微.     

光学计量用高速线阵CCD数据采集系统设计

介绍一种采用高速线阵 CCD 数据采集系统的设计过程。通过一片 MicroChip 公司的在线可编程微控制器对采集系统进行控制,并用标准 RS232 串行接口与外部进行数据通信和控制。在时序逻辑设计中,较好地解决了数据的存储、读取和点像元数据连续监测。实际应用表明该系统能满足光学干涉计量中线阵 CCD 数据采集要求。由于可以对线阵 CCD 进行单点、多点和整块数据的读取处理,因而可适应于不同周期、不同像素数目的线阵 CCD 传感器,以满足多种不同需求。     

Compact FPGA-based beamformer using oversampled 1-bit A/D converters

A compact medical ultrasound beamformer architecture that uses oversampled 1-bit analog-to-digital (A/D) converters is presented. Sparse sample processing is used, as the echo signal for the image lines is reconstructed in 512 equidistant focal points along the line through its in-phase and quadrature components. That information is sufficient for presenting a B-mode image and creating a color flow map. The high sampling rate provides the necessary delay resolution for the focusing. The low channel data width (1-bit) makes it possible to construct a compact beamformer logic. The signal reconstruction is done using finite impulse reponse (FIR) filters, applied on selected bit sequences of the delta-sigma modulator output stream. The approach allows for a multichannel beamformer to fit in a single field programmable gate array (FPGA) device. A 32-channel beamformer is estimated to occupy 50% of the available logic resources in a commercially available mid-range FPGA, and to be able to operate at 129 MHz. Simulation of the architecture at 140 MHz provides images with a dynamic range approaching 60 dB for an excitation frequency of 3 MHz.     

Accuracy of three‐dimensional analysis of regularized singularities

In computational mechanics, the quadrature of discontinuous and singular functions is often required. To avoid specialized quadrature procedures, discontinuous and singular fields can be regularized. However, regularization changes the algebraic structure of the solving equations, and this can lead to high errors. We show how to acquire accurate and consistent results when regularization is carried out. A three‐dimensional analysis of a tensile butt joint is performed through a regularized extended finite element method. The accuracy obtained via Gaussian quadrature is compared with that obtained by means of CUBPACK adaptive quadrature FORTRAN tool. The use of regularized functions with non‐compact and compact support is investigated through an error evaluation procedure based on the use of their Fourier transform. The proposed procedure leads to the remarkable conclusion that regularized delta functions with non‐compact support exhibit superior performance. Copyright © 2014 John Wiley & Sons, Ltd.     

Binary logic based purely on Fresnel diffraction

Binary logic operations on two-dimensional data arrays are achieved by use of the self-imaging properties of Fresnel diffraction. The fields diffracted by periodic objects can be considered as the superimposition of weighted and shifted replicas of original objects. We show that a particular spatial organization of the input data can result in logical operations being performed on these data in the considered diffraction planes. Among various advantages, this approach is shown to allow the implementation of dual-track, nondissipative logical operators. Image algebra is presented as an experimental illustration of this principle.     

Integer Representation of Decimal Numbers for Exact Computations

A scheme is presented and software is documented for representing as integers input decimal numbers that have been stored in a computer as double precision floating point numbers and for carrying out multiplications, additions and subtractions based on these numbers in an exact manner. The input decimal numbers must not have more than nine digits to the left of the decimal point. The decimal fractions of their floating point representations are all first rounded off at a prespecified location, a location no more than nine digits away from the decimal point. The number of digits to the left of the decimal point for each input number besides not being allowed to exceed nine must then be such that the total number of digits from the leftmost digit of the number to the location where round-off is to occur does not exceed fourteen.     

Neuro-fuzzy control of complex manufacturing processes

A scheme for intelligent optimization and control of complex manufacturing processes is presented. The underlying nonlinear process is modelled by artificial neural networks and process control is performed by fuzzy logic. Fuzzy rules are automatically generated from the trained neural networks through a novel rule generation mechanism and fuzzy control is performed by Mamdani implication. Simulation results show that the proposed approach can provide a robust and accurate way of controlling complex processes without comprehensive models or knowledge about the process.