Chuanming Ju, J. Zhang, Yong Zhang, Xianfeng Du, Zheng Yuan and Tangying Liu
The purpose of this paper is to present an algorithm for determining the inner and outer loops of arbitrary parametric surfaces.
Abstract
Purpose
The purpose of this paper is to present an algorithm for determining the inner and outer loops of arbitrary parametric surfaces.
Design/methodology/approach
The algorithm considers two sub-algorithms: one for non-closed surfaces and another one for closed surfaces. The first sub-algorithm named by area positive and negative method (APNM), combines a curve discretization algorithm with the polygon direction judgment algorithm to judge the inner and outer loops of non-closed surfaces. The second sub-algorithm, called by cross-period number method (CPNM), combines a curve discretization algorithm with the periodicity of closed surfaces to judge the type of boundary loops.
Findings
The APNM can use less CPU time to determining the inner and outer loops of the non-closed parametric surfaces. The CPNM can also determine the inner and outer loops of closed parametric surfaces effectively. The judgment results of loops can ensure that the direction of meshes generated on these surfaces is right. And finally ensure the correctness of the numerical simulation results.
Originality/value
Several numerical examples presented have verified the robustness and efficiency of the proposed algorithm. Compared with the conventional algorithm, the more complex the model, the more time the APNM saves in the process of determining the inner and outer loops for non-closed surfaces. The CPNM is also a new method to determining the inner and outer loops for closed parametric surfaces. The single run-time of CPNM is very small and can reach the level of microseconds.
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Chuanming Ju, Jiehao Chen, Ning Li and Xianfeng Du
A binary-tree subdivision method (BTSM) for numerical evaluation of weakly singular integrals with discontinuous kernel in the three-dimensional (3D) boundary element method (BEM…
Abstract
Purpose
A binary-tree subdivision method (BTSM) for numerical evaluation of weakly singular integrals with discontinuous kernel in the three-dimensional (3D) boundary element method (BEM) is presented in this paper.
Design/methodology/approach
In this method, the singular boundary element is split into two sub-elements and subdivided recursively until the termination criterion is met and the subdivision is stopped. Then, the source point is surrounded by one or more spherical cavities determined by the discontinuous kernel function. The sub-elements located in spherical cavities will be eliminated, and the regular triangular or rectangle elements are employed to fill the spherical cavities.
Findings
With the proposed method, the obtained sub-elements are automatically refined as they approach the source point, and they are “good” in shape and size for standard Gaussian quadrature. Thus, the proposed method can be used to evaluate singular integrals owing discontinuous kernel function accurately for cases of different element shapes and various source point locations.
Originality/value
Numerical examples show that the BTSM is suitable for planar and curved elements of arbitrary regular or irregular shape at various source point locations, and the results have much better accuracy and robustness than conventional subdivision method (CSM) when the kernel function is discontinuous.
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Chuanming Ju, J. Zhang, Yudong Zhong, Xianfeng Du, Jun Li and Baotao Chi
The purpose of this paper is to present an adaptive binary-tree element subdivision method (BTSM) for the evaluation of nearly singular integrals in three-dimensional boundary…
Abstract
Purpose
The purpose of this paper is to present an adaptive binary-tree element subdivision method (BTSM) for the evaluation of nearly singular integrals in three-dimensional boundary element method, which can facilitate automatic and high-quality patch generation.
Design/methodology/approach
In this method, the nearly singular element is split into two sub-elements. Each sub-element is then examined to determine if it is to be subdivided based on a specific subdivision criterion. The specific subdivision ensures that those sub-elements far from the source point are sparse. And then those sub-elements in close proximity to the source point are replaced by regular triangular elements.
Findings
With the proposed method, the sub-elements obtained are automatically refined as they approach the projection point, and they are “good” in shape and size for standard Gaussian quadrature. Thus, the proposed method can be used to evaluate nearly singular integrals accurately for cases of different element shapes and various locations of the source point.
Originality/value
Numerical examples for surface elements with various relative locations of the source point are presented. The results demonstrate that the proposed method has much better accuracy and robustness than some other methods.
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Pengfei Ge, Xiaoxu Wu, Bole Zhou and Xianfeng Han
This study aims to determine how and through what mechanisms the outward foreign direct investment (OFDI) promotion effect of the Belt and Road initiative (BRI-OFDI) affects…
Abstract
Purpose
This study aims to determine how and through what mechanisms the outward foreign direct investment (OFDI) promotion effect of the Belt and Road initiative (BRI-OFDI) affects domestic investment. It is motivated by the context that China is fostering a new development pattern, as well as by the impetus from the Belt and Road initiative for the new pattern.
Design/methodology/approach
Drawing on data of Chinese-listed companies, this study uses a difference-in-difference method to explore the effect of the BRI-OFDI on domestic investment and a mediation model to illustrate the mechanisms.
Findings
The BRI-OFDI has a significantly positive effect on domestic investment, meaning that the Belt and Road initiative's OFDI promotion effect crowds in domestic investment. The results are heterogeneous: the crowding-in effect mainly exists in non-state-owned and technology-intensive enterprises, while a crowding-out effect is seen in state-owned and labor-intensive enterprises. The easing of corporate financing constraints and the expansion of market demand are two important mechanisms.
Originality/value
This study uses the Belt and Road initiative as an exogenous shock to investigate the impact of the initiative-induced OFDI promotion effect on domestic investment. It addresses the potential endogeneity issue confronting the studies on the relationship between OFDI and domestic investment in the literature. The authors focus on the possible spillover effects of the Belt and Road initiative discussing the impact of the BRI-OFDI on domestic investment from the micro-firm perspective. It offers a new perspective to objectively assess the initiative's policy effect.
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Zhao Zhang and Xianfeng (Terry) Yang
This study aims to study the connected vehicle (CV) impact on highway operational performance under a mixed CV and regular vehicle (RV) environment.
Abstract
Purpose
This study aims to study the connected vehicle (CV) impact on highway operational performance under a mixed CV and regular vehicle (RV) environment.
Design/methodology/approach
The authors implemented a mixed traffic flow model, along with a CV speed control model, in the simulation environment. According to the different traffic characteristics between CVs and RVs, this research first analyzed how the operation of CVs can affect highway capacity under both one-lane and multi-lane cases. A hypothesis was then made that there shall exist a critical CV penetration rate that can significantly show the benefit of CV to the overall traffic. To prove this concept, this study simulated the mixed traffic pattern under various conditions.
Findings
The results of this research revealed that performing optimal speed control to CVs will concurrently benefit RVs by improving highway capacity. Furthermore, a critical CV penetration rate should exist at a specified traffic demand level, which can significantly reduce the speed difference between RVs and CVs. The results offer effective insight to understand the potential impacts of different CV penetration rates on highway operation performance.
Originality/value
This approach assumes that there shall exist a critical CV penetration rate that can maximize the benefits of CV implementations. CV penetration rate (the proportion of CVs in mixed traffic) is the key factor affecting the impacts of CV on freeway operational performance. The evaluation criteria for freeway operational performance are using average travel time under different given traffic demand patterns.
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Amanda de Paula Aguiar-Barbosa, Adriana Fumi Chim-Miki and Metin Kozak
The objective of this study was to analyze the evolution of tourism competitiveness over the years, ascertaining the state of the art and the degree of consensus among scholars on…
Abstract
Purpose
The objective of this study was to analyze the evolution of tourism competitiveness over the years, ascertaining the state of the art and the degree of consensus among scholars on its constituent elements to propose an integrative and updated concept.
Design/methodology/approach
A set of 130 definitions on tourism competitiveness formulated between 1999–2018 was analyzed and segmented into three periods, allowing its historical evolution to be ascertained. It is a qualitative and quantitative exploratory research that uses a combination of techniques, namely, content analysis, analysis of co-words and consensus analysis.
Findings
The results indicated a low use of elements such as the quality of life and the environment in the authors' definitions during 1999–2018, although these elements were present in the first concept of tourism competitiveness by Crouch and Ritchie (1999, 2003). Another finding of this study shows a reduction in the analysis of tourism competitiveness based on the supply and demand side. Nowadays, the research tends to turn on the basis of the population directly affected. It also reveals the enrichment of the theoretical corpus with new lines of research arising and new groups of scholars of the subject, consequently a new frontier in tourism competitiveness.
Research limitations/implications
The authors recommend deepening the analysis in each category of conceptual elements of tourism competitiveness to identify the origins of the low consensus. The authors also suggest conducting further research on the largest invisible schools of thought on this subject to understand their relations and perspectives, and thus to advance in the theoretical streams of the field. Finally, it is imperative to develop research on new models and monitors of tourism competitiveness that meet its renewed concept and integrate dimensions to consider the perspective of supply, demand, tourists and residents, as well as not excluding the economic bias but including the social side.
Practical implications
Owing to the fact that monitors of tourism competitiveness have practically no variables related to the social, most of the surveys are carried out from the supply or demand perspective, leaving the resident distant from the process. In this way, the results allow authors to indicate that new models of competitiveness measurement should be formulated based on the vision of the community impacted by tourism, i.e. a new version of tourism competitiveness not based on productivity but rather on the social aspect.
Originality/value
The findings of this study contribute to the field literature by offering an integrative concept of tourism competitiveness based on the elements with a higher level of consensus among researchers. Furthermore, the results accentuate a worrying fact regarding the operationalization of this concept, as the theoretical basis is not expressed in the monitors of competitiveness. Thus, nor it is possible in the management of the tourism industry.
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Leyi Cheng, Yinghan Wang and Yichuan Peng
The causes of high-speed railway failures are complex, and it is difficult to quantitatively and accurately describe safety evaluation. The purpose of this paper is to construct a…
Abstract
Purpose
The causes of high-speed railway failures are complex, and it is difficult to quantitatively and accurately describe safety evaluation. The purpose of this paper is to construct a model to ensure the safety of high-speed railway operations.
Design/methodology/approach
The authors construct a high-speed railway operation safety evaluation index system from four aspects: personnel, equipment, environment and management and analyze the inter-coupling relationship of various safety factors. Based on the evaluation index system, the use of network analytic hierarchy process (ANP) and fuzzy comprehensive evaluation will be used to establish a high-speed railway operation safety evaluation model.
Findings
Through the literature investigation and field investigation, combined with high-speed railway safety key points and system composition, 4 first-level indicators and 17 second-level indicators were selected to construct a high-speed railway operation safety evaluation index system. It can be seen from the results that the personnel management system and the signal and control system have the largest weight.
Originality/value
On the basis of establishing an evaluation index system, comprehensively considering the internal coupling relationship between evaluation indexes and the fuzziness of high-speed railway operation safety evaluation, high-speed railway uses ANP fuzzy network analysis method to construct high-speed railway operation, and the safety evaluation model has certain advantages and practicability in the case of the relative lack of high-speed railway operation data and fault data.