Wyniki wyszukiwania - Biblioteka Nauki

1

On regular copying languages

100%

Wang Y. , Hunter T.

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tom Vol. 11, No. 1

1--66

EN

This paper proposes a formal model of regular languages enriched with unbounded copying. We augment finite-state machinery with the ability to recognize copied strings by adding an unbounded memory buffer with a restricted form of first-in-first-out storage. The newly introduced computational device, finite-state buffered machines (FS-BMs), characterizes the class of regular languages and languages de-rived from them through a primitive copying operation. We name this language class regular copying languages (RCLs). We prove a pumping lemma and examine the closure properties of this language class. As suggested by previous literature (Gazdar and Pullum 1985, p.278), regular copying languages should approach the correct characteriza-tion of natural language word sets.

2

Assessing system impedance based on data regrouping

80%

Xu S. , Xiao X. , Wang Y. , Wu J.

Metrology and Measurement Systems

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2021

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tom Vol. 28, nr 1

191--208

EN

In recent years, assessing supply system impedance has become crucial due to the concerns on power quality and the proliferation of distributed generators. In this paper, a novel method is shown for passive measurement of system impedances using the gapless waveform data collected by a portable power quality monitoring device. This method improves the overall measurement accuracy through data regrouping. Compared with the traditional methods that use the consecutive measurement data directly, the proposed method regroups the data to find better candidates with less flotation on the system side. Simulation studies and extensive field tests have been conducted to verify the effectiveness of the proposed method. The results indicate that the proposed method can serve as a useful tool for impedance measurement tasks performed by utility companies.

3

An adaptive k nearest neighbour method for imputation of missing traffic data based on two similarity metrics

80%

Wang Y. , Xiao Y. , Lai J. , Chen Y.

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tom Vol. 54, iss. 2

59--73

EN

Traffic flow is one of the fundamental parameters for traffic analysis and planning. With the rapid development of intelligent transportation systems, a large number of various detectors have been deployed in urban roads and, consequently, huge amount of data relating to the traffic flow are accumulatively available now. However, the traffic flow data detected through various detectors are often degraded due to the presence of a number of missing data, which can even lead to erroneous analysis and decision if no appropriate process is carried out. To remedy this issue, great research efforts have been made and subsequently various imputation techniques have been successively proposed in recent years, among which the k nearest neighbour algorithm (kNN) has received a great popularity as it is easy to implement and impute the missing data effectively. In the work presented in this paper, we firstly analyse the stochastic effect of traffic flow, to which the suffering of the kNN algorithm can be attributed. This motivates us to make an improvement, while eliminating the requirement to predefine parameters. Such a parameter-free algorithm has been realized by introducing a new similarity metric which is combined with the conventional metric so as to avoid the parameter setting, which is often determined with the requirement of adequate domain knowledge. Unlike the conventional version of the kNN algorithm, the proposed algorithm employs the multivariate linear regression model to estimate the weights for the final output, based on a set of data, which is smoothed by a Wavelet technique. A series of experiments have been performed, based on a set of traffic flow data reported from serval different countries, to examine the adaptive determination of parameters and the smoothing effect. Additional experiments have been conducted to evaluate the competent performance for the proposed algorithm by comparing to a number of widely-used imputing algorithms.

4

Azo dye wastewater treatment in a novel three-dimensional electrode reactor

80%

Zou H. , Sun Z. , Jiao Z. , Wang Y.

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tom Vol. 48, nr 2

5--13

EN

A novel three-dimensional electrode reactor (3DER) was designed to treat the dye wastewater. The performance of 3DER was evaluated via methyl orange (MO) removal efficiency. For comparison, the performance of the two-dimensional electrode reactor (2DER) was also assessed. Furthermore, the effects of electrolyte and aeration on treatment performance were preliminarily evaluated to further optimize the operation on 3DER. A repeatable and stable MO treatment efficiency was obtained in the 3DER. The MO removal rate reached 79.5% at the applied voltage of 1.0 V, electrode spacing of 2 cm and initial MO concentration of 60 mg/dm3, significantly higher than that in the 2DER (58.8%), suggesting the obvious improvement of particle electrodes on MO removal. Both adding electrolyte and air sparging into the 3DER contributed to the enhancement of the MO removal rate. These results obtained here suggest that the 3DER may provide an effective alternative for the treatment of azo dye wastewater and/or non-biodegradable industrial wastewaters.

5

Low temperature synthesis of Cu0.1Co0.9Al2O4 blue ceramic pigment via the combustion method

61%

Wang Q. , Liu K. , Wang Y. , Wang C. , Wang Y. , Chang Q.

Materiały Ceramiczne

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2019

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tom T. 71, nr 4

389--396

EN

To date, CoAl2O4 has become a crucial pigment of ceramic decoration because of the rapid development of ceramic ink-jet technology. In this work, copper ions (10 mol%) doped CoAl2O4 blue pigment has been prepared by combustion method. Different to conventional CoAl2O4 pigment synthesized at high temperature (> 1000 °C), the synthesis temperature of Cu0.1Co0.9Al2O4 blue pigment is only 700 °C. Herein, we shed light on the underlying reasons of low temperature synthesis by investigating effects of heating temperature on the phase composition, microstructure and chromatic value. This study provides a low-cost and low-energy approach to the preparation of blue ceramic pigment. Using this strategy, the addition of Co can be reduced by 10% and the synthesis temperature can be reduced by more the 300 °C.

PL

Obecnie CoAl2O4 stał się kluczowym pigmentem do dekoracji ceramicznych ze względu na szybki rozwój ceramicznej technologii druku z wykorzystaniem atramentów ceramicznych. W niniejszej pracy przygotowano metodą spalania niebieski pigment CoAl2O4 domieszkowany jonami miedzi (10% mol.). W przeciwieństwie do konwencjonalnego pigmentu CoAl2O4 syntetyzowanego w wysokiej temperaturze (1000 °C), temperatura syntezy niebieskiego pigmentu Cu0,1Co0,9Al2O4 wynosi tylko 700 °C. W tym miejscu rzucamy światło na podstawowe przyczyny syntezy niskotemperaturowej, badając wpływ temperatury ogrzewania na skład fazowy, mikrostrukturę i wartość chromatyczną. Badanie to zapewnia tanie i energooszczędne podejście do przygotowania niebieskiego pigmentu ceramicznego. Stosując tę strategię, dodatek Co można zmniejszyć o 10%, a temperaturę syntezy można obniżyć o więcej niż 300 °C.

6

Dynamic failure mechanism of copper foil in laser dynamic flexible forming

51%

Shen Z. , Zhang L. , Li P. , Liu K. , Lin Y. , Zhou G. , Wang Y. , Zhang J. , Liu H. , Wang X.

Materials Science Poland

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2020

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tom Vol. 38, No. 4

684--692

EN

Laser dynamic flexible forming (LDFF) is a novel high velocity forming (HVF) technology, in which the foil metal is loaded by laser shock wave. Strain localization is readily to occur around the bulge edge, which will result in the ultimate dynamic failure. In this work, the microstructures before and after dynamic fracture are characterized by transmission electron microscopy (TEM) to investigate the dynamic failure mechanism. The plastic deformation regions of copper foil are composed of shock compression, strain localization and bulge. Microstructure refinement was observed in three different plastic deformation regions, particularly, dynamic recrystallization (DRX) occurs in the strain localization and bulge regions. In bulge region, extremely thin secondary twins in the twin/matrix (T/M) lamellae are formed. The microstructure features in the strain localization region show that superplastic flow of material exists until fracture, which may be due to DRX and subsequent grain boundary sliding (GBS) of the recrystallized grains. The grain coarsening in strain localization region may degrade the material flowing ability which results in the dynamic fracture.