Feng Chia University

Abstract Assume that a random sample is drawn from a population with unknown number of classes and possibly unequal class probabilities. A nonparametric estimation technique is proposed to estimate the number of classes using the idea of sample coverage, which is defined as the sum of the cell probabilities of the observed classes. Since expected sample coverage can be well estimated, we were motivated to find its role in the estimation of the number of classes. This work generalizes the result of Esty to a nonparametric approach and extends Darroch and Ratcliff to incorporate the heterogeneity of the class probabilities. The coefficient of variation of the class sizes is shown to play an important role in the recommended estimation procedures. The performance of the proposed estimators is investigated by means of Monte Carlo simulations.

Abstract: This paper examines whether the incidence of earnings management by UK firms depends on board monitoring. We focus on two aspects of board monitoring: the role of outside board members and the audit committee. Results indicate that the likelihood of managers making income‐increasing abnormal accruals to avoid reporting losses and earnings reductions is negatively related to the proportion of outsiders on the board. We also find that the chance of abnormal accruals being large enough to turn a loss into a profit or to ensure that profit does not decline is significantly lower for firms with a high proportion of outside board members. In contrast, we find little evidence that outside directors influence income‐decreasing abnormal accruals when pre‐managed earnings are high. We find no evidence that the presence of an audit committee directly affects the extent of income‐increasing manipulations to meet or exceed these thresholds. Neither do audit committees appear to have a direct effect on the degree of downward manipulation, when pre‐managed earnings exceed thresholds by a large margin. Our findings suggest that boards contribute towards the integrity of financial statements, as predicted by agency theory.

Significance Electrolysis of water to generate hydrogen fuel could be vital to the future renewable energy landscape. Electrodes that can sustain seawater splitting without chloride corrosion could address the issue of freshwater scarcity on Earth. Herein, a hierarchical anode consisting of a nickel–iron hydroxide electrocatalyst layer uniformly coated on a sulfide layer formed on Ni substrate was developed, affording superior catalytic activity and corrosion resistance in seawater electrolysis. In situ-generated polyanion-rich passivating layers formed in the anode are responsible for chloride repelling and high corrosion resistance, leading to new directions for designing and fabricating highly sustained seawater-splitting electrodes and providing an opportunity to use the vast seawater on Earth as an energy carrier.

Superhydrophobic and superoleophilic graphene-based sponges are demonstrated as efficient absorbents for a broad range of oils and organic solvents with high selectivity, good recyclability, and excellent absorption capacities up to 165 times their own weight. The findings show promise for large-scale removal of organic contaminants, especially in the field of oil spillage cleanup.

This paper develops a set of quantitative variables to characterise urban forms at the metropolitan level and, in particular, to distinguish compactness from 'sprawl'. It first reviews and analyses past research on the definitions of urban form, compactness and sprawl, and corresponding quantitative variables. Four quantitative variables are developed to measure four dimensions of urban form at the metropolitan level: metropolitan size, activity intensity, the degree that activities are evenly distributed, and the extent that high-density sub-areas are clustered. Through a series of simulation analyses, the global Moran coefficient, which characterises the fourth dimension, distinguishes compactness from sprawl. It is high, intermediate and close to zero for monocentric, polycentric and decentralised sprawling forms respectively. In addition, the more there is more local sprawl, composed of discontinuity and strip development, the lower is the Moran coefficient.

The band-edge optical response of transition metal dichalcogenides, an emerging class of atomically thin semiconductors, is dominated by tightly bound excitons localized at the corners of the Brillouin zone (valley excitons). A fundamental yet unknown property of valley excitons in these materials is the intrinsic homogeneous linewidth, which reflects irreversible quantum dissipation arising from system (exciton) and bath (vacuum and other quasiparticles) interactions and determines the timescale during which excitons can be coherently manipulated. Here we use optical two-dimensional Fourier transform spectroscopy to measure the exciton homogeneous linewidth in monolayer tungsten diselenide (WSe2). The homogeneous linewidth is found to be nearly two orders of magnitude narrower than the inhomogeneous width at low temperatures. We evaluate quantitatively the role of exciton-exciton and exciton-phonon interactions and population relaxation as linewidth broadening mechanisms. The key insights reported here—strong many-body effects and intrinsically rapid radiative recombination—are expected to be ubiquitous in atomically thin semiconductors.

In this letter, we present a reversible data hiding scheme based on histogram modification. We exploit a binary tree structure to solve the problem of communicating pairs of peak points. Distribution of pixel differences is used to achieve large hiding capacity while keeping the distortion low. We also adopt a histogram shifting technique to prevent overflow and underflow. Performance comparisons with other existing schemes are provided to demonstrate the superiority of the proposed scheme.

Technologies have driven big data collection across many fields, such as genomics and business intelligence. This results in a significant increase in variables and data points (observations) collected and stored. Although this presents opportunities to better model the relationship between predictors and the response variables, this also causes serious problems during data analysis, one of which is the multicollinearity problem. The two main approaches used to mitigate multicollinearity are variable selection methods and modified estimator methods. However, variable selection methods may negate efforts to collect more data as new data may eventually be dropped from modeling, while recent studies suggest that optimization approaches via machine learning handle data with multicollinearity better than statistical estimators. Therefore, this study details the chronological developments to mitigate the effects of multicollinearity and up-to-date recommendations to better mitigate multicollinearity.

CELLO2GO (http://cello.life.nctu.edu.tw/cello2go/) is a publicly available, web-based system for screening various properties of a targeted protein and its subcellular localization. Herein, we describe how this platform is used to obtain a brief or detailed gene ontology (GO)-type categories, including subcellular localization(s), for the queried proteins by combining the CELLO localization-predicting and BLAST homology-searching approaches. Given a query protein sequence, CELLO2GO uses BLAST to search for homologous sequences that are GO annotated in an in-house database derived from the UniProt KnowledgeBase database. At the same time, CELLO attempts predict at least one subcellular localization on the basis of the species in which the protein is found. When homologs for the query sequence have been identified, the number of terms found for each of their GO categories, i.e., cellular compartment, molecular function, and biological process, are summed and presented as pie charts representing possible functional annotations for the queried protein. Although the experimental subcellular localization of a protein may not be known, and thus not annotated, CELLO can confidentially suggest a subcellular localization. CELLO2GO should be a useful tool for research involving complex subcellular systems because it combines CELLO and BLAST into one platform and its output is easily manipulated such that the user-specific questions may be readily addressed.

In this paper, a number of problems of fundamental importance in a piezoelectric-piezomagnetic composite material are solved. The problems covered range from the derivation of the analytical expressions for the magneto-electro-elastic Eshelby tensors to the analysis of the magnetoelectric coupling effect which is a new property exhibited in the piezoelectric-piezomagnetic composite. In particular, when both the matrix and the inclusions of the composite are transversely isotropic with different magneto-electro-elastic moduli, and shapes of inclusions are of elliptic cylinder, circular cylinder, disk, and ribbon, closed-form solutions for the magnetoelectric coupling coefficientS are presented compactly. The resulting solutions are a function of the shape of inclusion, phase properties, and volume fraction of the inclusions. These results could provide us with insight into how a piezoelectric-piezomagnetic composite material consisting of inclusions will perform and would be helpful in understanding the magneto-electric-elastic behavior of the composite.

Abstract This research aims to develop a framework of consumer–brand relationship by taking an experiential view. In this article, the authors report a cross‐cultural comparative study that was conducted on a sample of real consumers at coffee chain stores in Shanghai, China, and Taipei, Taiwan. The findings reveal that individual as well as shared experiences work through brand association, brand personality, brand attitude, and brand image to shape a consumer–brand relationship. © 2006 Wiley Periodicals, Inc.

This study examines the role of cognitive and affective destination-image components in the formation of destination preferences from a multialternative/multiattribute perspective. In addition, the study examines the stability of those roles across three types of destinations. A total of 1,020 Taichung residents in Taiwan were administered an on-site questionnaire. The results indicated that cognitive and affective components of overall destination image influence tourists' destination preferences and that cognitive image impacts affective image. However, the importance of the two image components varied across natural, developed, and theme-park destinations. In addition, the findings confirmed that while some image attributes are universally important, other attributes are only important for specific types of destinations. Implications for theory, practice, and future research are provided.

A hybrid antenna is proposed for future 4G/5G multiple input multiple output (MIMO) applications. The proposed antenna is composed of two antenna modules, namely, 4G antenna module and 5G antenna module. The 4G antenna module is a two-antenna array capable of covering the GSM850/900/1800/1900, UMTS2100, and LTE2300/2500 operating bands, while the 5G antenna module is an eight-antenna array operating in the 3.5-GHz band capable of covering the C-band (3400-3600 MHz), which could meet the demand of future 5G application. Compared with ideal uncorrelated antennas in an 8 × 8 MIMO system, the 5G antenna module has shown good ergodic channel capacity of ~40 b/s/Hz, which is only 6 b/s/Hz lower than ideal case. This multi-mode hybrid antenna is fabricated, and typically, experimental results such as S-parameter, antenna efficiency, radiation pattern, and envelope correlation coefficient are presented.

In 2014, Turkanovic et al. proposed a smart card-based authentication scheme for heterogeneous ad hoc wireless sensor network. This scheme is very efficient since it employs only hash function and XOR operation. However, we found that Turkanovic et al.'s scheme is vulnerable to impersonation attack with node capture, stolen smart card attack, sensor node spoofing attack, stolen verifier attack, and fails to ensure backward secrecy. We propose an efficient scheme to overcome all those weaknesses. Moreover, we also propose an advanced scheme, which provides perfect forward secrecy without much modification from the first proposed scheme.

The protection level offered by filtering facepiece particulate respirators and face masks is defined by the percentage of ambient particles penetrating inside the protection device. There are two penetration pathways: (1) through the faceseal leakage, and the (2) filter medium. This study aimed at differentiating the contributions of these two pathways for particles in the size range of 0.03-1 microm under actual breathing conditions. One N95 filtering facepiece respirator and one surgical mask commonly used in health care environments were tested on 25 subjects (matching the latest National Institute for Occupational Safety and Health fit testing panel) as the subjects performed conventional fit test exercises. The respirator and the mask were also tested with breathing manikins that precisely mimicked the prerecorded breathing patterns of the tested subjects. The penetration data obtained in the human subject- and manikin-based tests were compared for different particle sizes and breathing patterns. Overall, 5250 particle size- and exercise-specific penetration values were determined. For each value, the faceseal leakage-to-filter ratio was calculated to quantify the relative contributions of the two penetration pathways. The number of particles penetrating through the faceseal leakage of the tested respirator/mask far exceeded the number of those penetrating through the filter medium. For the N95 respirator, the excess was (on average) by an order of magnitude and significantly increased with an increase in particle size (p < 0.001): approximately 7-fold greater for 0.04 microm, approximately 10-fold for 0.1 microm, and approximately 20-fold for 1 microm. For the surgical mask, the faceseal leakage-to-filter ratio ranged from 4.8 to 5.8 and was not significantly affected by the particle size for the tested submicrometer fraction. Facial/body movement had a pronounced effect on the relative contribution of the two penetration pathways. Breathing intensity and facial dimensions showed some (although limited) influence. Because most of the penetrated particles entered through the faceseal, the priority in respirator/mask development should be shifted from improving the efficiency of the filter medium to establishing a better fit that would eliminate or minimize faceseal leakage.

A unified method based on the inclusion formulation is proposed to determine the magnetic, electric, and elastic fields in a composite with piezoelectric and piezomagnetic phases. The composite reinforcements are treated as ellipsoidal inclusions that enable the reinforcement geometries ranging from thin flakes to continuous fibers. Utilizing the proposed method, the magneto-electro-elastic tensors analogous to Eshelby tensors for elastic ellipsoidal inclusions are obtained. With these tensors, the magnetic, electric, and elastic fields around the inclusion as well as concentration factors are determined. Furthermore, based upon the Mori–Tanaka mean-field theory [Acta Metall. 21, 571 (1973)] to account for the interaction between inclusions and matrix, the effective magneto-electro-elastic constants (elastic moduli, piezoelectric coefficients, dielectric constants, piezomagnetic coefficients, magnetoelectric, and magnetic permeability) of the composites are expressed explicitly in terms of phase properties, volume fraction, and inhomogeneity shape. The numerical examinations have been conducted for the three-dimensional BaTiO3–CoFe2O4 composite, and the overall composite behavior has been examined numerically. It is found that the composite reveals interesting magnetoelectric coupling which is absent in each constituent.

This paper introduces a novel algorithm that increases the efficiency of the current cloud-based smart-parking system and develops a network architecture based on the Internet-of-Things technology. This paper proposed a system that helps users automatically find a free parking space at the least cost based on new performance metrics to calculate the user parking cost by considering the distance and the total number of free places in each car park. This cost will be used to offer a solution of finding an available parking space upon a request by the user and a solution of suggesting a new car park if the current car park is full. The simulation results show that the algorithm helps improve the probability of successful parking and minimizes the user waiting time. We also successfully implemented the proposed system in the real world.

A dual-polarized hybrid eight-antenna array operating in the 2.6-GHz band (2550-2650 MHz) for 5G communication multi-input multi-output (MIMO) operation in the smartphone is presented. The proposed hybrid antenna array elements are symmetrically placed along the long edges of the smartphone, and they are composed of two different four-antenna array types (C-shaped coupled-fed and L-shaped monopole slot) that exhibit orthogonal polarization. Therefore, coupling between the two antenna array types can be reduced, and the MIMO system performances are enhanced. A prototype of the proposed eight-antenna array is manufactured and measured. A good impedance matching (10 dB return loss or better), desirable cross-polarization discrimination (better than 15 dB), and an acceptable isolation (better than 12.5 dB) are obtained. Envelope correlation coefficient and channel capacity are also calculated to evaluate the MIMO performances of the proposed antenna array.

ABSTRACT Creativity research on the personality approach has focused on the relationship between individual attributes and innovative behavior. However, few studies have empirically examined the effects of positive psychological traits on innovative behavior in an organizational setting. This study examines the relationships among creative self‐efficacy, optimism, and innovative behavior as well as the moderating effect of optimism. Longitudinal data across two periods were collected from 120 spa employees of a diet and beauty salon company in Taiwan. After controlling for the effects of job tenure and the Big Five personality traits, this study found that employees with a high level of creative self‐efficacy demonstrate a high level of innovative behavior at work, and optimism does not have a direct effect on employees' innovative behavior, but it does play a moderating role. When employees' creative self‐efficacy is high, those with greater optimism exhibit greater innovative behavior at work. Toward the end, this paper offers suggestions for future research and discusses the practical implications of this study.

Graphene–gold metasurface architectures that can provide significant gains in plasmonic detection sensitivity for trace-amount target analytes are reported. Benefiting from extreme phase singularities of reflected light induced by strong plasmon-mediated energy confinements, the metasurface demonstrates a much-improved sensitivity to molecular bindings nearby and achieves an ultralow detection limit of 1 × 10−18 m for 7.3 kDa 24-mer single-stranded DNA. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.