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Article
Publication date: 19 June 2017

Yang Xin, Yi Liu, Zhi Liu, Xuemei Zhu, Lingshuang Kong, Dongmei Wei, Wei Jiang and Jun Chang

Biometric systems are widely used for face recognition. They have rapidly developed in recent years. Compared with other approaches, such as fingerprint recognition…

Abstract

Purpose

Biometric systems are widely used for face recognition. They have rapidly developed in recent years. Compared with other approaches, such as fingerprint recognition, handwriting verification and retinal and iris scanning, face recognition is more straightforward, user friendly and extensively used. The aforementioned approaches, including face recognition, are vulnerable to malicious attacks by impostors; in such cases, face liveness detection comes in handy to ensure both accuracy and robustness. Liveness is an important feature that reflects physiological signs and differentiates artificial from real biometric traits. This paper aims to provide a simple path for the future development of more robust and accurate liveness detection approaches.

Design/methodology/approach

This paper discusses about introduction to the face biometric system, liveness detection in face recognition system and comparisons between the different discussed works of existing measures.

Originality/value

This paper presents an overview, comparison and discussion of proposed face liveness detection methods to provide a reference for the future development of more robust and accurate liveness detection approaches.

Details

Sensor Review, vol. 37 no. 3
Type: Research Article
ISSN: 0260-2288

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Article
Publication date: 21 March 2016

Mingyu Nie, Zhi Liu, Xiaomei Li, Qiang Wu, Bo Tang, Xiaoyan Xiao, Yulin Sun, Jun Chang and Chengyun Zheng

This paper aims to effectively achieve endmembers and relative abundances simultaneously in hyperspectral image unmixing yield. Hyperspectral unmixing, which is an…

Abstract

Purpose

This paper aims to effectively achieve endmembers and relative abundances simultaneously in hyperspectral image unmixing yield. Hyperspectral unmixing, which is an important step before image classification and recognition, is a challenging issue because of the limited resolution of image sensors and the complex diversity of nature. Unmixing can be performed using different methods, such as blind source separation and semi-supervised spectral unmixing. However, these methods have disadvantages such as inaccurate results or the need for the spectral library to be known a priori.

Design/methodology/approach

This paper proposes a novel method for hyperspectral unmixing called fuzzy c-means unmixing, which achieves endmembers and relative abundance through repeated iteration analysis at the same time.

Findings

Experimental results demonstrate that the proposed method can effectively implement hyperspectral unmixing with high accuracy.

Originality/value

The proposed method present an effective framework for the challenging field of hyperspectral image unmixing.

Details

Sensor Review, vol. 36 no. 2
Type: Research Article
ISSN: 0260-2288

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Article
Publication date: 1 March 2021

Waluyo Adi Siswanto, Kirill Borodin, Zaid Hamid Mahmoud, A. Surendar, Sami Sajjadifar, Galiya Abdilova and Jun Chang

The purpose of this study is to investigate the effect of aging temperature on the barrel-type solder joint lifetime of electronic devices and to include these effects in…

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Abstract

Purpose

The purpose of this study is to investigate the effect of aging temperature on the barrel-type solder joint lifetime of electronic devices and to include these effects in the modified prediction model.

Design/methodology/approach

Several accelerated shear stress tests under different stress amplitudes and aging temperatures were performed.

Findings

It was found that by aging temperature increasing, the lifetime decreases. Morrow energy model was also found as the best prediction model when the aging temperature is taken into consideration.

Originality value

It is confirmed.

Details

Soldering & Surface Mount Technology, vol. 33 no. 4
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 20 March 2017

Wei Wei, Jun Chang, Qingjie Huang, Qiang Wang, Yuanyuan Liu and Zengguang Qin

As measurement results of optical gas sensors are constantly affected by the pressure of a target gas, approaches must be taken to modify the results. The purpose of this…

Abstract

Purpose

As measurement results of optical gas sensors are constantly affected by the pressure of a target gas, approaches must be taken to modify the results. The purpose of this paper is to compare the traditional measurement method with the new measurement system. At the same time, measurement results of the two systems under different pressures are presented for comparison of the detection performance.

Design/methodology/approach

A theoretical model of line shape function and its impact on the measured results is presented, which is based on direct absorption and wavelength modulation spectroscopy (WMS) for gas concentration detection under different pressures. Methods of linear fitting and result modification have been illustrated and compared. A new testing system with the result modification method used for water vapor concentration detection under different pressures between 1 and 7 atm is applied. With an additional pressure sensor placed in the gas cell and calibration performed, relationships between the amplitude of the second harmonic and concentration of the target gas under different pressures can be obtained.

Findings

Amplitude detection can be used for concentration detection regardless of the change in pressure for the method of direct absorption. Although, WMS with second harmonic detection is not enough. Two methods are presented and compared with WMS under different pressures. Moreover, the result modification method shows better performance as computation is significantly reduced.

Originality/value

The comparison between linear fitting and the result modification method with WMS under different pressures is firstly presented. At the same time, a new testing system with better performance for water vapor concentration detection under different pressures is presented as well.

Details

Sensor Review, vol. 37 no. 2
Type: Research Article
ISSN: 0260-2288

Keywords

Content available
Article
Publication date: 30 May 2004

Jun Hui Lee and Kook Hyun Chang

This paper discusses theoretical extensions of the implied volatility method of Dupire (1994) when the stock prices follow the Geometric Levy process. For the extensions…

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1

Abstract

This paper discusses theoretical extensions of the implied volatility method of Dupire (1994) when the stock prices follow the Geometric Levy process. For the extensions of Kolmogorov forward equation for Levy process, this paper uses adjoint operator in L² spaces. This paper obtains similar results of Dupire (1994) and Andersen and Andreasan (2001). However, our results can be applied to more general semi-martingale processes such as well-known VG (Variance Gamma) model and NIG (Normal Inverse Gaussian) model with diffusion processes. This paper also applies the approach to the case of stochastic time changed Levy process, which generates the stochastic volatility models.

Details

Journal of Derivatives and Quantitative Studies, vol. 12 no. 1
Type: Research Article
ISSN: 2713-6647

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Article
Publication date: 29 July 2014

Feng-biao He and Jun Chang

The purpose of this paper is to establish a combined forecasting model to predict regional logistics demand, which is an important procedure on decision making of regional…

Abstract

Purpose

The purpose of this paper is to establish a combined forecasting model to predict regional logistics demand, which is an important procedure on decision making of regional logistics planning.

Design/methodology/approach

There are several kinds of mathematical models often used in forecasting regional logistics demand. Trend extrapolation method extrapolates the future development trends bases on the hypothesis that the regional logistics will develop steadily. Grey system method predicts the change of logistics demand by the generation and development of original data sequence and excavation of inherent rules of the original data. Regression method obtains the change rules through the analysis between explained variable and explanatory variables. Each method has unique characteristics. In order to improve the accuracy of the prediction, combined methods are established. Genetic algorithm is used to determine the weights of different single models.

Findings

The results show that the combined forecasting model optimised by genetic algorithm can improve the accuracy.

Practical implications

Combined forecasting model can integrate the advantages of different single forecasting models. The key of improving the accuracy is to determine the weights of single forecasting models. Genetic algorithm can do well in finding suitable weights of each single forecasting model.

Originality/value

The paper succeeds in providing a combined forecasting model using genetic algorithm to determine the weights of each single prediction model, which helps to the decision making of regional logistics demand.

Details

Grey Systems: Theory and Application, vol. 4 no. 2
Type: Research Article
ISSN: 2043-9377

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Article
Publication date: 7 January 2014

Lee-Lee Chong, Xiao-Jun Chang and Siow-Hooi Tan

The purpose of this study is to delineate the factors influencing the use of financial derivatives by non-financial firms in managing their exchange rate exposure. In…

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Abstract

Purpose

The purpose of this study is to delineate the factors influencing the use of financial derivatives by non-financial firms in managing their exchange rate exposure. In total, 219 non-financial firms are surveyed in regard to their financial hedging decision.

Design/methodology/approach

This study is conducted via a survey and the questionnaires were sent to the treasurers and financial controller of the firms. Descriptive analysis is employed to assess the profiles of the respondents. Then, factor analysis is carried out to determine the factors influencing the use of financial derivatives in Malaysia.

Findings

The results indicate that the hedging decision of non-financial firms is influenced by their assertive level toward the market and regulators and also how flexible they are for derivative instruments. The intellectual capability that firms acquire to perform hedging strategies is also vital in influencing them to make hedging decision.

Practical implications

The insights of this survey would assist and prepare firms to hedge their exchange rate risk by employing financial derivatives. Knowing the influences of firms' adoption of currency derivatives would allow policy makers to formulate their policies in boosting the liquidity of Malaysian derivative market.

Originality/value

This study presents findings on the factors influencing the execution of financial hedging by non-financial firms in Malaysia. Survey data are used to seek for the feedback from the market players in order to provide empirical evidence on the corporate use of financial hedging.

Details

Managerial Finance, vol. 40 no. 2
Type: Research Article
ISSN: 0307-4358

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Article
Publication date: 18 December 2019

C. Min Han and Hyojin Nam

The purpose of this paper is to examine how consumer ethnocentrism (CET) and cosmopolitanism (COS) may affect Asian consumers’ perceptions of out-group countries and their…

Abstract

Purpose

The purpose of this paper is to examine how consumer ethnocentrism (CET) and cosmopolitanism (COS) may affect Asian consumers’ perceptions of out-group countries and their products, doing so by examining similar vs dissimilar countries across countries of origin. Given the strong inter-country rivalries that exist among Asian countries, the authors propose two alternative hypotheses, drawing from social identity theory and realistic group conflict theory.

Design/methodology/approach

To test the hypotheses, the authors examine consumer perceptions of both Western countries (dissimilar out-groups) and Asian countries (similar out-groups) within China (Study 1). In addition, the authors investigate how CET and COS affect consumer perceptions of Asian countries in Japan and in non-Asian dissimilar countries, and compare the effects between the two regions (Study 2).

Findings

The findings indicate that CET shows greater negative effects on perceptions of a country and its products, when the country is from a similar out-group than when it is from a dissimilar one. On the other hand, COS showed equally strong positive effects among consumers for both similar and dissimilar out-group countries.

Research limitations/implications

The results suggest that Asian consumers feel a sense of intergroup rivalry with other Asian countries, and, as a result, exhibit a greater degree of ethnocentric biases toward these countries and their products than they do toward Western countries and products. Also, the results suggest that COS may transcend national differences and inter-country rivalries in consumer consumption tendencies.

Originality/value

The study examines inter-country similarities as a moderator of CET and COS effects, which has not been extensively researched in the past. In addition, the study discusses the concept of intergroup rivalry among neighboring countries and examines how it affects consumer perceptions of out-group countries and their products in Asia, where strong inter-country rivalries exist.

Details

International Marketing Review, vol. 37 no. 1
Type: Research Article
ISSN: 0265-1335

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Article
Publication date: 28 October 1988

James A. Lee

America’s patent rate (per 100,000 population) rose steeply to 34 from 1820‐1885, hovered between 28‐36 for the next 40 years then started its plunge to the present 18…

Abstract

America’s patent rate (per 100,000 population) rose steeply to 34 from 1820‐1885, hovered between 28‐36 for the next 40 years then started its plunge to the present 18. This article examines the numerous possible causes often found in the literature ‐ expenditures on R&D, poor patent protection, high fees and pendency delays, decline in education in sciences and engineering, etc. While there is some evidence to support each of these, none is as important as the decline in our immigrants from Europe. Projections of possible improvements in our creativity and innovation in sciences and technology are bound in the characteristics of our present and future immigrant streams, and these are not expected to replace the role played by our previous immigrant streams.

Details

American Journal of Business, vol. 3 no. 2
Type: Research Article
ISSN: 1935-5181

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Article
Publication date: 13 November 2009

George K. Stylios

Examines the fifthteenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched…

Abstract

Examines the fifthteenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects. Subjects discussed include cotton fabric processing, asbestos substitutes, textile adjuncts to cardiovascular surgery, wet textile processes, hand evaluation, nanotechnology, thermoplastic composites, robotic ironing, protective clothing (agricultural and industrial), ecological aspects of fibre properties – to name but a few! There would appear to be no limit to the future potential for textile applications.

Details

International Journal of Clothing Science and Technology, vol. 21 no. 6
Type: Research Article
ISSN: 0955-6222

Keywords

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