Time-pulse logarithmic transistorized converter

Conclusions Transistorized logarithmic time-pulse converters which provide an operating error not exceeding 0.1% with a relatively simple circuit can be used in various measuring and computing devices which require logarithmic functional conversion of information.     

A hardware algorithm for fast logarithmic computation with exponential convergence rate

Abstract

A hardware algorithm is proposed for improving the speed of the linear digit‐recurrence logarithmic algorithm. The convergence rate of this logarithmic algorithm is exponential. Furthermore, the size of the lookup tables used in the algorithm is smaller than the size of the lookup tables used in the digit‐recurrence algorithms. When the word length of the operand is less than or equal to 64 bits, the operations involved in each stage of the logarithmic computation only include small table lookup operation, digit‐multiplication, and simple square operations. We conclude that the hardware implementation of our proposed algorithm is very efficient.     

Universal coders for automatic measuring systems

Conclusions The above block schematics of universal multichannel coding functional converters can be used for making up automatic digital measuring systems. By means of these converters the measuring systems acquire computing characteristics which provide an evaluation and correction of errors due, for instance, to the nonlinearity of continuous information transducers. Moreover, the functional coding operation considerably widens the application of measuring equipment with a digital output by extending it to indirect measurements. It should be noted that the solution of a similar problem of functional coding by combining linear coding converters with electronic functional converters of a continuous type (for instance, diode functional converters) leads to more cumbersome, less reliable devices whose coding accuracy is inferior to that of the functional devices described in this article. Moreover, in using functional converters of a continuous type it is difficult to provide multiconditional coding operations. Translated from Izmeritel'naya Tekhnika, No. 11, pp. 30–35, November, 1961     

Design of metamirrors for linear to circular polarization conversion with super-octave bandwidth

In this paper, bandwidth improvement of reflection-mode linear to circular polarization converters (RMCPs) is studied. The proposed RMCP is based on multi-layer rectangular patches. Equivalent transmission line circuit of multi-layer reflection-mode polarization converters is used for designing the proposed metamirror. In addition, the approximate equation of axial ratio (AR) of the reflected wave is obtained from the structures containing rectangular patches on each layer. Polarization converters containing multi-layer rectangular patches can be utilized for different ranges of frequencies. However, the frequency range of 2–8 THz is considered in this paper without losing generality. The incident wave is assumed to be linearly polarized with 45° polarization angle. AR equation is used for initial optimization of the dimensions of rectangular patches to obtain the widest possible bandwidth of RMCPs with two- and three-layer patches. Secondary optimization is applied after specifying largest dimensions of the unit cell and excluding them from the variables of optimization. Finally, modified dimensions of the three-layer RMCP are obtained using parametrical study in simulations. The proposed three-layer polarization converter has the 3 dB axial ratio bandwidth of more than 116% and the permitted incident angle of higher than 25°.     

带有积压定单的最优模糊存储模型

本文提出一个新的具有积压定单的关于模糊总需求的模糊存储模型。在模糊函数原理下，给出了模糊总存储成本。为了寻找最优解，使用积分均值法白化模糊总存储成本，利用Lingo8．0求解不等式约束问题，我们发现最优解都是确定的实数。此外，当模糊总需求是确定的实数时，我们提出模型的最优解与经典的具有积压定单存储模型具有相同的结果。     

Logarithmic Analog-to-Digital Converters: A Survey

Analog-to-digital converters (ADC) with logarithmic law are receiving particular attention from system and circuit designers. They can be applied to solve many problems of data acquisition and encoding found in almost all the fields of experimental physics and instrumentation dealing with analog variables with several decades of dynamic range, where a constarnt relative accuracy, rather than a constant absolute accuracy, is required. Spme proposals and realizations of logarithmic ADC (LADC) already presented in the literature are discussed as well as some new ideas organized according to three classes of schemes. The first can be viewed as the cascade connection of an analog logarithmic information converter and a conventional ADC; while in the second, the LADC is entirely digital and follows the ADC; and in the third, the logarithmic conversion and the A/D conversion are performed by the same structure and cannot be easily distinguished. An analysis is made of the performances of the various possible realizations as well as of their complexity.     

Nano Wave Plates Structuring and Index Matching in Transparent Hydroxyapatite-YAG: Ce Composite Ceramics for High Luminous Efficiency White Light-Emitting Diodes

Replacing traditional luminous silicone or resins with phosphor in ceramics (PiCs) as color converters has been proposed as an efficient way to improve thermal stability of high-power white light-emitting diodes (WLEDs). However, excessive light scattering in existing PiCs results in enormous phosphor-converted light losses, which makes the luminosity of current PiCs color converters less efficient and means that they can only be used in devices working in reflective mode. By introducing nano wave plate structuring and Rayleigh scattering, luminous hydroxyapatite (HA)-YAG: Ce ceramics are prepared from mesoporous HA nanorods and YAG: Ce phosphors at 850 °C, enabling for the first time WLEDs equipped with PiC color converters in transmission mode. With low-temperature sintering and a highly transparent matrix, the quantum yield of HA-YAG: Ce retains ≈90% of the raw phosphor, and WLEDs with the color converters exhibit a record luminous efficiency of 170 lm W⁻¹ and a correlated color temperature below 4500 K. A facile and practical strategy of using nano structural modulation to eliminate birefringence-induced light scattering for fabricating high-performance ceramic converters suitable for multiple mode luminaires is demonstrated.     

Material handling improvement in warehouses by parts clustering

A major part of warehouse operations is related to the collection of parts from the warehouse which is called the Order Picking Problem. To improve order picking operations, the total travel distance and generally picking time must be reduced. In this paper, a two-level approach is proposed that determines the locations of parts in the warehouse. The first step clusters parts into part families. Four different clustering methods based on principal component analysis, singular value decomposition and Two-Step Cluster Component are applied. In the second step, four different heuristics are proposed to determine the locations of parts. In addition to the minimisation of travel distance, we also consider the minimisation of the total congestion in aisles due to multiple workers. The proposed algorithms also consider the interactions between part families to minimise intergroup movements. As a result of the implementation, we achieved more than 40% reduction in material handling compared to the current set-up of the warehouse. The applied algorithms can easily be modified to be used for warehouses with different configurations. The algorithms utilised in this case study can be helpful to researchers to become familiar with new heuristics, as well as practitioners to design improved warehouses.     

On-chip, time-correlated, fluorescence lifetime extraction algorithms and error analysis

A new, simple, and hardware-only fluorescence-lifetime-imaging microscopy (FLIM) is proposed to implement on-chip lifetime extractions, and their signal-to-noise-ratio based on statistics theory is also deduced. The results are compared with Monte Carlo simulations, giving good agreement. Compared with the commonly used iterative least-squares method or the maximum-likelihood-estimation- (MLE-) based, general purpose FLIM analysis software, our algorithm offers direct calculation of fluorescence lifetime based on the collected photon counts stored in on-chip counters and therefore delivers faster analysis for real-time applications, such as clinical diagnosis. Error analysis considering timing jitter based on statistics theory is carried out for the proposed algorithms and is also compared with MLE to obtain optimized channel width or measurement window and bit resolution of the time-to-digital converters for a given accuracy. A multi-exponential, pipelined fluorescence lifetime method based on the proposed algorithms is also introduced. The performance of the proposed methods has been tested on mono-exponential and four-exponential decay experimental data.     

量子电压标定的叠加型噪声温度计研究

针对传统开关切换型噪声温度计存在测量时间长且需要匹配传输线的问题,搭建了一种量子电压标定的叠加型噪声温度计,从而消除切换开关。该方案一方面不需要匹配传输线,另一方面允许增加传感器电阻阻值从而提高测量的信噪比。系统主要包括量子电压赝噪声源、低噪声放大滤波电路和高精度数据采集电路等模块。采用四阶拟合外推到直流以消除传输线效应的影响,从而得到正确的热力学温度值。恒温实验室的验证性实验表明,经过100 s测量得到的结果与名义温度值的相对偏差为0.027%、不确定度为0.16%,说明了所提出方案的可行性。     

Modeling of Eddy-Current Loss of Electrical Machines and Transformers Operated by Pulsewidth-Modulated Inverters

Pulsewidth-modulated (PWM) inverters are used more and more to operate electrical machines and to interface renewable energy systems with the utility grid. However, there are abundant high-frequency harmonics in the output voltage of a PWM inverter, which increase the iron losses and result in derating of the machine or transformer connected to them. Predicting the iron losses caused by the PWM supply is critical for the design of electrical machines and transformers operated by PWM inverters. These losses are primarily attributed to eddy-current loss caused by the PWM supply. In this paper, after analyzing the harmonic components of PWM voltage, we derive the effects of different parameters of PWM switching on the eddy-current loss. We compare the iron losses modeled with the proposed analytical methods on a three-phase transformer, a dc motor, and an induction motor with the results of time-stepping finite-element analysis and experiments. We provide detailed equations for the prediction of iron losses. These equations can be directly applied in the design and control of PWM converters and electric motors to improve energy efficiency in electrical machines and transformers operated from PWM converters.      

An enhanced method for characterizing successive approximationconverters

A strategy for characterizing successive approximation, analog-to-digital converters with quad current switch architectures is described. It permits detailed parameter specification (accuracy and linearity) without recourse to testing every transition voltage. The results show an encouraging reduction in the residual error from 0.144 step (from a currently used test) to 0.048 step with the proposed test for the specific case of 12-b converters. To achieve this result, only 2.6% of the transition voltages require measurement. The percentage of codes to be tested reduces dramatically as the number of bits of the converter increases. The evolution of the proposed test is investigated by examining the cause and effect of superposition errors     

On a new extension of Weibull distribution: Properties,estimation, and applications to one and two causes of failures

In this paper, we try to supplement the distribution theory literature by introducing a new distribution, called the logarithmic transformed Weibull (LTW) distribution by logarithm transformation method. The proposed distribution exhibits constant, decreasing, increasing, unimodal and unimodal then bathtub-shaped hazard rates. Although our main focus is on the estimation from the frequentist point of view, in addition, we derive some useful structural and statistical properties of the proposed LTW distribution. The LTW parameters are estimated by eight frequentist methods of estimation. We perform extensive simulation experiments to show the performances of the proposed estimators. Applications of the model are presented by reanalyzing two real data sets, and comparisons are made with the fit attained by some other well-known distributions for illustrative purposes. As an illustration, one data set is analyzed for competing risks to demonstrate the flexibility of the proposed model.     

Electrochemical synthesis of thin CdS films

Thin cadmium sulfide (CdS) films have been electrochemically synthesized on metal substrates and the related photosensitive surface barrier structures have been obtained. The proposed method can be used in the technology of thin-film photoelectric converters with large areas.     

Deep Reinforcement Learning-Based Job Shop Scheduling ofSmartManufacturing

Industry 4.0 production environments and smart manufacturing systems integrate both the physical and decision-making aspects of manufacturing operations into autonomous and decentralized systems. One of the key aspects of these systems is a production planning, specifically, Scheduling operations on the machines. To cope with this problem, this paper proposed a Deep Reinforcement Learning with an Actor-Critic algorithm (DRLAC). We model the Job-Shop Scheduling Problem (JSSP) as a Markov Decision Process (MDP), represent the state of a JSSP as simple Graph Isomorphism Networks (GIN) to extract nodes features during scheduling, and derive the policy of optimal scheduling which guides the included node features to the best next action of schedule. In addition, we adopt the Actor-Critic (AC) network’s training algorithm-based reinforcement learning for achieving the optimal policy of the scheduling. To prove the proposed model’s effectiveness, first, we will present a case study that illustrated a conflict between two job scheduling, secondly, we will apply the proposed model to a known benchmark dataset and compare the results with the traditional scheduling methods and trending approaches. The numerical results indicate that the proposed model can be adaptive with real-time production scheduling, where the average percentage deviation (APD) of our model achieved values between 0.009 and 0.21 compared with heuristic methods and values between 0.014 and 0.18 compared with other trending approaches.     

Efficient digital image watermarking for mobile applications by optimising the spread spectrum technique

In this paper, the spread spectrum watermarking in wavelet domain is optimised by using a number of techniques to make it more efficient when executed by a platform running on mobile devices. The proposed techniques can be executed efficiently and consume less computational and power resources as compared to the conventional spread spectrum-based watermarking. The proposed technique represents binary bits in the watermark using symbols, wherein each symbol represents at least 2 binary bits. A symbol is then mapped into a pseudo noise sequence and embedded in the digital image. Our analytical results show that our schemes reduce the number of operations required for watermarking by ～50%, while our experimental results show that our schemes save about ～59 and ～67% in processing time and energy consumption, respectively.     

An analytical model for bending and springback of bimetallic sheets

Springback is an inevitable phenomenon due to elastic redistribution of internal stresses occurring in sheet metal forming operations. Most of the research reported in this area has been concerned with the components formed from single metal. This article deals with the analytical solution for prediction of springback in bending of bimetallic sheets. A mathematical model is derived based on Woo and Marshall's constitutive equation, considering logarithmic strain (nonlinear) distribution across the thickness and thickness change during bending. Analytical modeling, based on logarithmic strain distribution across the thickness, can be used for accurate springback predictions in the case of smaller bend radius to the thickness ratio. The results of the springback and thickness change are validated using experimental results for the aluminum sheet layered with steel. Further, springback variation in bimetallic sheets is studied, with a change in material properties and thickness of each layer.     

Decomposition of samples of used ceramic-based automotive catalytic converters in analytical autoclaves with resistive heating

Different ways of chemical sample preparation of used automotive catalytic converters (ACCs) in analytical autoclaves with resistive heating are studied for subsequent determination of platinum, palladium, and rhodium by AES-ICP. Conditions of autoclave decomposition of ACCs samples using binary mixtures of HCl-HNO₃ and HCl-H₂O₂ that allow achieving quantitative extraction of platinum group metals into a solution without complete decomposition of the sample are determined. Universal methods of analysis of used ceramic-based automotive catalytic converters are developed. The relative standard deviation of the analysis results according to the developed techniques is 11-5% rel. at contents of platinum, palladium, and rhodium from 0.03% to 0.3%.     

A Multiple-Precision Study on the Modified Collocation Trefftz Method

Recently, Liu (CMES 21(2007), 53) developed the modified collocation Trefftz method (MCTM) by setting a characteristic length slightly larger than the maximum radius of the computational domain. In this study, we find that the range of admissible characteristic length can be significantly enlarged if the LU decomposition is applied for solving the resulted dense unsymmetric matrix. Furthermore, we discover a range formula for admissible characteristic length, in which the number of the T-complete functions, the shape of the computation domain, and the exponent bits of the involved floating-point arithmetic have been taken into consideration. In order to validate the prescribed formula for different exponent bits, the multiple precision floating-point reliable (MPFR) library is used. In addition, we find that the MCTM is a numerical method of exponential convergence. In other words, increasing the numbers of the T-complete functions can reduce the logarithmic error proportionally till the precision limit, which can be set up for the MPFR library. Numerical experiments are carried out to demonstrate that the proposed MCTM with the LU decomposition can solve the Laplace equation stably and accurately, even for a Cauchy problem. A multiple-precision comparison between the MCTM and the method of fundamental solution is also preformed.     

Optimising two dwell point policies for AS/RSs with input and output point at opposite ends of the aisle

Automated storage and retrieval systems (AS/RSs) are widely used for storing and retrieving products in all types of warehouses. Dwell point policy is a vital control policy that can greatly affect the performance of AS/RSs. In this paper, we study dwell point policies in AS/RSs with input and output stations at opposite ends of the aisle. We first propose two dwell point policies. We find that five existing dwell point policies in the literature are special cases of exactly one of our policies. We then develop expected travel time models for the proposed policies, solve these models with the objective of minimising expected travel time, and obtain closed-form solutions for the optimal dwell location(s). We prove that one proposed policy dominates the other in terms of expected travel time. Numerical experiments are performed to quantify the percentage gap of expected travel time between the proposed policies and policies in the literature. We find that, in some situations, the better proposed policy can achieve up to 8%–10% reduction in expected travel time in comparison with the best literature policy. A real-data case study validates that these situations arise with high probability in typical daily warehouse operations.