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1 – 10 of 14Chen‐Yuan Chen, Hsien‐Chueh Peter Yang, Cheng‐Wu Chen and Tsung‐Hao Chen
This study aims to apply a systematic statistical approach, including several plot indexes, to diagnose the goodness of fit of a logistic regression model, and then to detect the…
Abstract
Purpose
This study aims to apply a systematic statistical approach, including several plot indexes, to diagnose the goodness of fit of a logistic regression model, and then to detect the outliers and influential observations of the data from experimental data.
Design/methodology/approach
The proposed statistical approach is applied to analyze some experimental data on internal solitary wave propagation.
Findings
A suitable logistic regression model in which the relationship between the response variable and the explanatory variables is found. The problem of multicollinearity is tested. It was found that certain observations would not have the problem of multicollinearity. The P‐values for both the Pearson and deviance χ2 tests are greater than 0.05. However, the Pearson χ2 value is larger than the degrees of freedom. This finding indicates that although this model fits the data, it has a slight overdispersion. After three outliers and influential observations (cases 11, 27, and 49) are removed from the data, and the remaining observations are refitted the goodness‐of‐fit of the revised model to the data is improved.
Practical implications
A comparison of the four predictive powers: R2, max‐rescaled R2, the Somers' D, and the concordance index c, shows that the revised model has better predictive abilities than the original model.
Originality/value
The goodness‐of‐fit and prediction ability of the revised logistic regression model are more appropriate than those of the original model.
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Keywords
Meng‐Lung Lin, Cheng‐Wu Chen, Qiu‐Bing Wang, Yu Cao, Jyh‐Yi Shih, Yung‐Tan Lee, Chen‐Yuan Chen and Shin Wang
The growing rate of desertification in Northwestern China and Mongolia that is occurring as a result of the conflict between economic development and natural conservation has been…
Abstract
Purpose
The growing rate of desertification in Northwestern China and Mongolia that is occurring as a result of the conflict between economic development and natural conservation has been demonstrated in many studies. There have, for example, been some large studies using variations in bi‐weekly normalized difference vegetation index (NDVI) satellite images as a parameter for evaluating the vegetation dynamics in these areas. The purpose of this paper is to identify multi‐temporal variation in vegetated and non‐vegetated areas in remotely sensed satellite images to assess the status of desertification in East Asia.
Design/methodology/approach
Spatial data derived from these satellite images are applied to evaluate vegetation dynamics on a regional level, to identify the areas most vulnerable to desertification.
Findings
Analytical results indicate that the desert areas in East Asia are primarily distributed over Southern Mongolia, Central and Western Inner Mongolia, and Western China (the Taklimakan Desert). These desert areas expanded from 2000 to 2002, shrunk in 2003, then expanded again from 2003 to 2005. The areas most at risk for desertification are principally distributed in Southeastern Mongolia, and Eastern Inner Mongolia.
Originality/value
Simulation results based on data for deserts distributed throughout Northwestern China and Mongolia indicate that the proposed fuzzy model‐based method would be helpful for assessing and monitoring desertification. These analytical results will help administrators refine planning processes, define the boundaries of protected areas, and facilitate decisions for prioritizing areas for desertification protection.
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Cheng‐Wu Chen, Chien‐wen Shen, Chen‐Yuan Chen and Ming‐Jen Cheng
A tension leg platform (TLP) is a vertically moored, floating structure which is normally used for offshore oil/gas production. However, these types of structures can be damaged…
Abstract
Purpose
A tension leg platform (TLP) is a vertically moored, floating structure which is normally used for offshore oil/gas production. However, these types of structures can be damaged by vibration responses that are too large. The purpose of this paper is to consider the influence of the external waves on oceanic structures.
Design/methodology/approach
A mathematical model of an ocean environment was constructed, in which wave‐induced flow fields cause structural surge motion, then solutions to the mathematical model were analytically derived.
Findings
The Takagi‐Sugeno (T‐S) fuzzy model is employed in the approximation of the oceanic structure. The stability analysis of the TLP system is carried out using the Lyapunov direct method.
Practical implications
The dependence of the wave‐induced flow field and its resonant frequency on the wave characteristics and the structural properties of the platform, which include width, thickness and mass, can be drawn using a parametric approach.
Originality/value
Mathematical modeling is applied to find the wave‐induced displacement due to the surge motion. The vibration of the mechanical motion of the platform structure caused by wave force is also discussed.
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Keywords
Cheng‐Wu Chen, Chen‐Yuan Chen, Peter Hsien‐Chueh Yang and Tsung‐Hao Chen
This study seeks to develop a systematic means of identifying regression models using a complex regression model with a statistical method.
Abstract
Purpose
This study seeks to develop a systematic means of identifying regression models using a complex regression model with a statistical method.
Design/methodology/approach
As a widely adopted statistical scheme for analyzing multifactor data, regression analysis provides a conceptually simple algorithm for examining functional relationships among variables. This investigation assesses the proposed relationship using a sample of data in regression analysis and then estimates the fit using statistics. Furthermore, several algorithms and added variable plots are presented to obtain an appropriate regression model and the relationship between response variables y, p and explanatory variables x0,x1,x2, … ,xp.
Findings
The proposed statistical scheme is demonstrated by the analysis of experimental data on internal waves, in which the results can well illustrate what has been investigated in laboratory experiment and may be applicable to the naturally occurring reflection of internal waves from sloping bottoms.
Practical implications
In previous studies, field observations of internal waves were carried out. Owing to the limit of stationary measurement in situ, sufficient experiment data were not easily obtained. On the other hand, data collected by laboratory experiments express more information on wave mechanism, such as energy dissipation, mixing efficiency, and stratification thickness in a stratified layer fluid system. In present study, the authors supply valuable experiment data and analytic method, which will be a great contribution to the geophysical fluid dynamics. The results illustrate well what has been investigated in laboratory experiment and may be applicable to the naturally occurring reflection of internal waves from sloping bottoms.
Originality/value
More recently, it has been proposed that internal wave mixing may contribute significantly to internal mixing in the ocean and hence has an important influence on world climatic changes. Based on the statistical algorithm and regression model, the reduction in internal wave energy can be predicted on a sloping bottom due to frictional effect. Since, interaction between internal waves and uniform slopes has occurred in an estuary, a lake or in the ocean, the results available in this paper would benefit future study on internal wave hydrodynamics.
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Chung‐Hung Tsai, Cheng‐Wu Chen, Wei‐Ling Chiang and Meng‐Lung Lin
Fuzzy theory provides a rigorous, flexible approach to the problem of defining and computing. Therefore, to facilitate decision making in a geographic information system (GIS)…
Abstract
Purpose
Fuzzy theory provides a rigorous, flexible approach to the problem of defining and computing. Therefore, to facilitate decision making in a geographic information system (GIS), the graph layer indicator and the Takagi‐Sugeno (T‐S) fuzzy model must be integrated. This study aims to explain several versions of the T‐S fuzzy model based on fuzzy theory and fuzzy operation.
Design/methodology/approach
An inference model is constructed for GIS using the T‐S fuzzy model to formulate an integrated T‐S decision‐making (TSDMK) system.
Findings
The TSDMK system accommodates inexact, linguistic, vague and uncertain GIS data. The operator assigns most graph layer indicators by intuition.
Practical implications
Simulation results for the Hualien main station show that the proposed TSDMK system is an effective approach for GIS decision making.
Originality/value
This investigation assesses applications of fuzzy logic for decision making in a GIS based on TSDMK graphs focusing on model‐based systems.
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Keywords
Wei‐Ling Chiang, Dung‐Jiang Chiou, Cheng‐Wu Chen, Jhy‐Pyng Tang, Wen‐Ko Hsu and Te‐Yu Liu
This study aims to investigate the relationship between structural damage and sensitivity indices using the Hilbert‐Huang transform (HHT) method.
Abstract
Purpose
This study aims to investigate the relationship between structural damage and sensitivity indices using the Hilbert‐Huang transform (HHT) method.
Design/methodology/approach
The relationship between structural damage and the sensitivity indices is obtained by using the HHT method. Three sensitivity indices are proposed: the ratio of rotation (RR), the ratio of shifting value (SV) and the ratio of bandwidth (RB). The nonlinear single degree of freedom and multiple degree of freedom models with various predominant frequencies are constructed using the SAP2000 program. Adjusted PGA El Centro and Chi‐Chi (TCU068) earthquake data are used as the excitations. Next, the sensitivity indices obtained using the HHT and the fast Fourier transform (FFT) methods are evaluated separately based on the acceleration responses of the roof structures to earthquakes.
Findings
Simulation results indicate that, when RR < 1, the structural response is in the elastic region, and neither the RB nor SV in the HHT and FFT spectra change. When the structural response is nonlinear, i.e. RR1, a positive trend of change occurs in RB and RR, while in the HHT spectra, SV increases with an increasing RR. Moreover, the FFT spectra reveal that SV changes only when the RR is sufficiently large. No steady relationship between the RB and the RR can be found.
Originality/value
The paper demonstrates the effectiveness of the HHT method.
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Keywords
Meng‐Lung Lin and Cheng‐Wu Chen
The purpose of this paper is to better understand landscape dynamics in arid and semi‐arid environments. Land degradation has recently become an important issue for land…
Abstract
Purpose
The purpose of this paper is to better understand landscape dynamics in arid and semi‐arid environments. Land degradation has recently become an important issue for land management in western China. The oasis ecosystem is especially sensitive to environmental disturbances, such as abnormal/extreme precipitation events, variations in the water supply from the upper watersheds, fluctuations in temperature, etc. Satellite remote sensing of terrestrial ecosystems can provide us with the temporal dynamics and spatial distributions of green cover over large areas of landscape. Seasonal green cover data are especially important in assessing landscape health (e.g. desertification, rate of urban sprawl, natural disturbances) in arid and semi‐arid regions. In this study, green cover data are derived from vegetation indices retrieved from moderate resolution imaging spectroradiometer (MODIS) sensors onboard the satellite Terra.
Design/methodology/approach
Satellite images recorded during the period from April 2000 to December 2005 are analyzed and the spatial distribution and temporal changes of the Ejin Oasis quantified.
Findings
This study shows that it is possible to derive important parameters linked to landscape sensitivity from MODIS and the derived imagery, such as normalized difference vegetation index (NDVI) time‐series data. Such a MODIS‐based time‐series monitoring system is particularly useful in arid and semi‐arid environments. The results of landscape sensitivity analysis prove the effectiveness of the method in assessing landscape sensitivity from the years 2001‐2005.
Practical implications
The novel strategy used in this investigation is based on the T‐S fuzzy model, which is in turn based on fuzzy theory and fuzzy operations.
Originality/value
Simulation results based on fuzzy models will help to improve the monitoring techniques used to evaluate land degradation and to estimate the newest tendency in landscape green cover dynamics in the Ejin Oasis.
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Khalil Ahmad, Bhuvanesh Sharma, Ritesh Khatwani, Mahima Mishra and Pradip Kumar Mitra
This paper aims to explore the impact of metaverse technology on the hospitality and tourism industry. The introduction of metaverse technology has revolutionised the way the…
Abstract
Purpose
This paper aims to explore the impact of metaverse technology on the hospitality and tourism industry. The introduction of metaverse technology has revolutionised the way the hospitality and tourism industry works. In the present study, the authors have investigated the role of social media marketing in the adoption of metaverse technology in hotel booking in India.
Design/methodology/approach
An extended technology acceptance model was proposed for an empirical investigation in the Indian context. Sample of 344 respondents was collected across India using a purposive sampling technique for the purpose of data analysis. The structural model analysis is used to analyse the data collected from the respondents using the SmartPLS software to check the structural and the measurement fit of the model.
Findings
The adoption intentions were largely influenced by the utility, attitude (ATT) and ease of use of the technology, and social media marketing plays a major role in influencing the perceived usefulness (PU) and ease of use (PEU). The study finds positive ATTs of the customers for using metaverse technology for booking their hotels. PU and PEU significantly influence the ATT of the consumer indicating the traveller’s perception of the usefulness and ease of metaverse technology influence their ATTs towards adoption.
Originality/value
Influence of metaverse technology is at a nascent stage in India specifically for hotel booking and tourism. The authors have used discriminant validity by using the criteria for both the square root of the average variance extracted and heterotrait–monotrait ratio tests, and the results suggest that the constructs in the research are distinct from other.
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ZY Chen, Yahui Meng, Ruei-Yuan Wang and Timothy Chen
To prove the effectiveness of the proposed design method, this study aims to propose the Fisher equation and temperature cooling fins that control high-speed aerospace vehicles.
Abstract
Purpose
To prove the effectiveness of the proposed design method, this study aims to propose the Fisher equation and temperature cooling fins that control high-speed aerospace vehicles.
Design/methodology/approach
A new approach whereby the control of aerospace vehicles can be achieved by fuzzy controller and appropriate Navier–Stokes equations in this article. The design of the controller based on models of Navier–Stokes equations simplified complex mathematical simulations and approximations.
Findings
If the fuzzy controller cannot stabilize the system, the Navier–Stokes fuzzy function is injected into the system as a controller tool, and the system is asymptotically stabilized by adjusting the fuzzy parameters.
Originality/value
The simulation results show that if the tuning frequency is high enough, the fuzzy controller and fuzzy observer can create chaotic movements by adjusting the dither amplitude appropriately. The demonstration of the Fisher equation and the temperature-cooled fin control problem for high-speed aerospace vehicles has displayed the benefits of combining fuzzy control with the Navier–Stokes equation.
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Lei‐Yu Wu, Chun‐Ju Wang, Chun‐Yao Tseng and Ming‐Cheng Wu
The purpose of this paper is to develop a framework to link founding team and start‐up competitive advantage in the context of the Taiwanese technology‐based ventures.
Abstract
Purpose
The purpose of this paper is to develop a framework to link founding team and start‐up competitive advantage in the context of the Taiwanese technology‐based ventures.
Design/methodology/approach
The paper analyzes 211 start‐ups of the technology‐based sector and verifies the relationship between entrepreneur resources, trust, founding team partners' commitments, and start‐up competitive advantage.
Findings
In technology‐based start‐ups, the competitive advantage of a start‐up is determined by the founding team partners' commitments and the resources an entrepreneur has.
Research limitations/implications
This study is retrospective which relies on technology‐based founding team members as the primary research subjects, some respondents may observe the performance of their start‐ups today and then make attributions about the past to explain that performance.
Practical implications
Utilizations of personal networks are important in the early stage of technology‐based start‐ups; through networking and using trust, an entrepreneur can gain the critical resources and competitive advantage required in the development of a business.
Originality/value
In technology‐based start‐ups, trust, not the resources an entrepreneur has, is an effective way by which entrepreneurs can win founding team partners' commitments.
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