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1 – 10 of over 2000
Article
Publication date: 29 August 2019

Song Gao, Jory Seguin, Wagdi G. Habashi, Dario Isola and Guido Baruzzi

This work aims to describe the physical and numerical modeling of a CFD solver for hypersonic flows in thermo-chemical non-equilibrium. This paper is the second of a…

130

Abstract

Purpose

This work aims to describe the physical and numerical modeling of a CFD solver for hypersonic flows in thermo-chemical non-equilibrium. This paper is the second of a two-part series that concerns the application of the solver introduced in Part I to adaptive unstructured meshes.

Design/methodology/approach

The governing equations are discretized with an edge-based stabilized finite element method (FEM). Chemical non-equilibrium is simulated using a laminar finite-rate kinetics, while a two-temperature model is used to account for thermodynamic non-equilibrium. The equations for total quantities, species and vibrational-electronic energy conservation are loosely coupled to provide flexibility and ease of implementation. To accurately perform simulations on unstructured meshes, the non-equilibrium flow solver is coupled with an edge-based anisotropic mesh optimizer driven by the solution Hessian to carry out mesh refinement, coarsening, edge swapping and node movement.

Findings

The paper shows, through comparisons with experimental and other numerical results, how FEM + anisotropic mesh optimization are the natural choice to accurately simulate hypersonic non-equilibrium flows on unstructured meshes. Three-dimensional test cases demonstrate how, for high-speed flows, shocks resolution, and not necessarily boundary layers resolution, is the main driver of solution accuracy at walls. Equally distributing the error among all elements in a suitably defined Riemannian space yields highly anisotropic grids that feature well-resolved shock waves. The resulting high level of accuracy in the computation of the enthalpy jump translates into accurate wall heat flux predictions. At the opposite end, in all cases examined, high-quality but isotropic unstructured meshes gave very poor solutions with severely inadequate heat flux distributions not even featuring expected symmetries. The paper unequivocally demonstrates that unstructured anisotropically adapted meshes are the best, and may be the only, way for accurate and cost-effective hypersonic flow solutions.

Originality/value

Although many hypersonic flow solvers are developed for unstructured meshes, few numerical simulations on unstructured meshes are presented in the literature. This work demonstrates that the proposed approach can be used successfully for hypersonic flows on unstructured meshes.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 2
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 21 June 2019

Jory Seguin, Song Gao, Wagdi George Habashi, Dario Isola and Guido Baruzzi

This paper aims to describe the physical and numerical modeling of a new computational fluid dynamics solver for hypersonic flows in thermo-chemical non-equilibrium. The…

142

Abstract

Purpose

This paper aims to describe the physical and numerical modeling of a new computational fluid dynamics solver for hypersonic flows in thermo-chemical non-equilibrium. The code uses a blend of numerical techniques to ensure accuracy and robustness and to provide scalability for advanced hypersonic physics and complex three-dimensional (3D) flows.

Design/methodology/approach

The solver is based on an edge-based stabilized finite element method (FEM). The chemical and thermal non-equilibrium systems are loosely-coupled to provide flexibility and ease of implementation. Chemical non-equilibrium is modeled using a laminar finite-rate chemical kinetics model while a two-temperature model is used to account for thermodynamic non-equilibrium. The systems are solved implicitly in time to relax numerical stiffness. Investigations are performed on various canonical hypersonic geometries in two-dimensional and 3D.

Findings

The comparisons with numerical and experimental results demonstrate the suitability of the code for hypersonic non-equilibrium flows. Although convergence is shown to suffer to some extent from the loosely-coupled implementation, trading a fully-coupled system for a number of smaller ones improves computational time. Furthermore, the specialized numerical discretization offers a great deal of flexibility in the implementation of numerical flux functions and boundary conditions.

Originality/value

The FEM is often disregarded in hypersonics. This paper demonstrates that this method can be used successfully for these types of flows. The present findings will be built upon in a later paper to demonstrate the powerful numerical ability of this type of solver, particularly with respect to robustness on highly stretched unstructured anisotropic grids.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 7
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 8 May 2017

Hongwei Wang, Song Gao, Pei Yin and James Nga-Kwok Liu

Comparative opinions widely exist in online reviews as a common way of expressing consumers’ ideas or preferences toward certain products. Such opinion-rich texts are key…

1204

Abstract

Purpose

Comparative opinions widely exist in online reviews as a common way of expressing consumers’ ideas or preferences toward certain products. Such opinion-rich texts are key proxies for detecting product competitiveness. The purpose of this paper is to set up a model for competitiveness analysis by identifying comparative relations from online reviews for restaurants based on both pattern matching and machine learning.

Design/methodology/approach

The authors define the sub-category of comparative sentences according to Chinese linguistics. Classification rules are set up for each type of comparative relations through class sequence rule. To improve the accuracy of classification, a comparative entity dictionary is then introduced for further identifying comparative sentences. Finally, the authors collect reviews for restaurants from Dianping.com to conduct experiments for testing the proposed model.

Findings

The experiments show that the proposed method outperforms the baseline methods in terms of precision in identifying comparative sentences. On the basis of such comparison-rich sentences, product features and comparative relations are extracted for sentiment analysis, and sentimental score is assigned to each comparative relation to facilitate competitiveness analysis.

Research limitations/implications

Only the explicit comparative relations are discussed, neglecting the implicit ones. Besides that, the study is grounded in the assumption that all features are homogeneous. In some cases, however, the weights to different aspects are not of the same importance to market.

Practical implications

On the basis of comparative relation mining, product features and comparative opinions are extracted for competitiveness analysis, which is of interest to businesses for finding weakness or strength of products, as well as to consumers for making better purchase decisions.

Social implications

Comparative relation mining could be possibly applied in social media for identifying relations among users or products, and ranking users or products, as well as helping companies target and track competitors to enhance competitiveness.

Originality/value

The authors propose a research framework for restaurant competitiveness analysis by mining comparative relations from online consumer reviews. The results would be able to differentiate one restaurant from another in some aspects of interest to consumers, and reveal the changes in these differences over time.

Details

Industrial Management & Data Systems, vol. 117 no. 4
Type: Research Article
ISSN: 0263-5577

Keywords

Book part
Publication date: 4 December 2020

Marko Jakšič and Marko Budler

Outsourcing of business-logistics services is a well-established business practice that allows an outsourcer to obtain the services or products from a logistics-service…

Abstract

Outsourcing of business-logistics services is a well-established business practice that allows an outsourcer to obtain the services or products from a logistics-service provider (LSP). The outsourcer can order a range of logistics services, including but not limited to warehousing, transportation, and forwarding. The outsourcers had traditionally focused on service-provider selection criteria such as costs, quality, and responsiveness while having devoted considerably less attention to how sustainably the practices are carried out. Past research identified different external and internal motivators that facilitate consideration of sustainability in selection of the service providers, whereas the current study investigates the outsourcers’ perception of importance of environmental sustainability in adoption of green logistics practices and selection of LSPs. We use a vantage point of outsourcers (“buyers”) to conduct the quantitative research based on a survey conducted on large manufacturing companies. The findings reveal a (mis)match between the perception of importance and realized inclusion of environmental-sustainability criteria. Ultimately, this study finds a link between the levels of perception and rate of adoption, and provides recommendations for the future adoption of environmental-sustainability criteria in the selection of the LSPs.

Details

Challenges on the Path Toward Sustainability in Europe
Type: Book
ISBN: 978-1-80043-972-6

Keywords

Open Access
Article
Publication date: 3 June 2022

XiYue Deng, Xiaoming Li, Zhenzhen Chen, Mengli Zhu, Naixue Xiong and Li Shen

Human group behavior is the driving force behind many complex social and economic phenomena. Few studies have integrated multi-dimensional travel patterns and city…

111

Abstract

Purpose

Human group behavior is the driving force behind many complex social and economic phenomena. Few studies have integrated multi-dimensional travel patterns and city interest points to construct urban security risk indicators. This paper combines traffic data and urban alarm data to analyze the safe travel characteristics of the urban population. The research results are helpful to explore the diversity of human group behavior, grasp the temporal and spatial laws and reveal regional security risks. It provides a reference for optimizing resource deployment and group intelligence analysis in emergency management.

Design/methodology/approach

Based on the dynamics index of group behavior, this paper mines the data of large shared bikes and ride-hailing in a big city of China. We integrate the urban interest points and travel dynamic characteristics, construct the urban traffic safety index based on alarm behavior and further calculate the urban safety index.

Findings

This study found significant differences in the travel power index among ride-sharing users. There is a positive correlation between user shared bike trips and the power-law bimodal phenomenon in the logarithmic coordinate system. It is closely related to the urban public security index.

Originality/value

Based on group-shared dynamic index integrated alarm, we innovatively constructed an urban public safety index and analyzed the correlation of travel alarm behavior. The research results fully reveal the internal mechanism of the group behavior safety index and provide a valuable supplement for the police intelligence analysis.

Details

Data Technologies and Applications, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 2514-9288

Keywords

Article
Publication date: 8 March 2022

Som Sekhar Bhattacharyya

The purpose of this paper is to comprehend the nature of online reviews received on various social networking sites and internet-based platforms regrading organizational…

Abstract

Purpose

The purpose of this paper is to comprehend the nature of online reviews received on various social networking sites and internet-based platforms regrading organizational corporate social responsibility (CSR) initiatives.

Design/methodology/approach

Given the novelty of this field, a qualitative exploratory research study was carried out. For this research, 28 Indian CSR experts on online CSR reviews were interviewed with a semi-structured open-ended questionnaire for data collection. Thematic and relational content analysis was applied for data analysis. The data was analysed based upon the theoretical anchors of micro foundations approach, organizational egoism (reputational and economic) concept and organizational logic (instrumental and integrative) literature and stakeholder salience.

Findings

The study analysis indicated that online CSR reviews that organizations received on various social networking sites and internet-based platforms from different individual and institutional stakeholders were complaints, appreciations, observations and recommendations in nature. Online CSR reviews appreciated more of integrative organizational logic than instrumental organizational logic. CSR reviews present on online platforms valued organizational reputational egoism more than organizational economic egoism. The salience of stakeholders was getting redefines in Web 2.0 based online CSR reviews. Finally, micro foundations approach was becoming a more potent perspective in the CSR narrative.

Research limitations/implications

This research study was anchored in the micro foundations approach of CSR (Hafenbrädl and Waeger, 2017). This study ascertained those individuals did matter in organizational CSR narrative (Maak et al., 2016). Furthermore, how firms were evaluated through online reviews based upon organizational egoism (reputational and economic) (Casali, 2011; Casali and Day, 2015) and organizational logic (instrumental and integrative) (Seele and Lock, 2015; Liu, 2013; Gao and Bansal, 2013; Bansal and Song, 2017) was studied. Finally, in the world of online reviews, the notion of salient stakeholders (Mitchell et al., 2011; Magness, 2008) was getting redefined, and this aspect was also covered in this research study.

Practical implications

Firms have been engaging in CSR initiatives towards provision of social benefits and community engagement. Regarding firm CSR initiatives, CSR managers traditionally used to receive feedback from the stakeholders based upon written and special surveys conducted post or during the late stages of CSR engagement. The advent and ubiquitous presence of digital mobile devices and Web 2.0-enabled internet connections altered the way firms received feedback. This was because increasingly online reviews were received from stakeholders on firm CSR web pages, social networking sites and other online spaces. Many of the online CSR reviews were regarding the compliments and achievements that the CSR initiatives had achieved. However, a significant portion of online CSR reviews were regarding the complaints regarding the CSR initiatives. Online CSR reviews received from an array of stakeholders are inputs for firm managers. Online CSR reviews are thus an asset for an organization. Managers need to develop capabilities towards applying this asset for the expressed purposed. These online CSR reviews could be used as inputs to draw new CSR initiatives, redefine extant CSR initiatives. Furthermore, these online CSR reviews could be used as inputs to alter the organizational resources, capabilities, competencies and process regarding CSR initiatives.

Originality/value

This was one of the first studies that integrated the theoretical aspects of salient stakeholders, organizational logic, organizational egoism through the lens of micro foundations approach in the context of organizational CSR initiatives. To the best of the author’s knowledge, this was indeed a novel contribution, as the same was explored and explicated based upon online CSR reviews on internet-based platforms.

Details

International Journal of Organizational Analysis, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1934-8835

Keywords

Article
Publication date: 13 April 2010

Liang Zhang, Song-bai Xue, Li-li Gao, Yan Chen, Sheng-lin Yu, Zhong Sheng and Guang Zeng

The purpose of this paper is to investigate the effects of minor addition of the rare earth (RE) element cerium, Ce, on the microstructures and creep properties of…

Abstract

Purpose

The purpose of this paper is to investigate the effects of minor addition of the rare earth (RE) element cerium, Ce, on the microstructures and creep properties of Sn-Ag-Cu solder alloys.

Design/methodology/approach

The pure Sn, Sn-Cu alloy, Sn-Ag alloy and Cu-Ce alloy were used as raw materials. Sn-Ag-Cu alloys with different contents of RE Ce were chosen to compare with Sn-Ag-Cu. The raw materials of Sn, Sn-Cu alloy, Sn-Ag alloy, Cu-Ce alloy were melted in a ceramic crucible, and were melted at 550°C ± 1°C for 40 minutes. To homogenize the solder alloy, mechanical stirring was performed every ten minutes using a glass rod. During the melting, KC1 + LiCI (1.3:1), were used over the surface of liquid solder to prevent oxidation. The melted solder was chill cast into a rod.

Findings

It is found that the microstructure exhibits smaller grains and the Ag3Sn/Cu6Sn5 intermetallic compound (IMC) phases are modified in matrix with the addition of Ce. In particular, the addition of 0.03 wt.% Ce to the Sn-Ag-Cu solder can refine the microstructures and decrease the thickness of the IMC layers of Sn-Ag-Cu solder alloys. Meanwhile, thermodynamic analysis showed that these phenomena could be attributed to the reduction of the driving force for Cu-Sn IMC formation due to the addition of Ce. Results calculated using the thermodynamic method are close to the above experimental data. Thus, the optimum content of Ce in Sn-Ag-Cu solder alloys should be about 0.030 percent. Additionally, the effect of Ce on the creep rupture life of Sn-Ag-Cu soldered joints was studied. It was found that the creep rupture life may be increased up to 7.5 times more than that of the original Sn-Ag-Cu alloy, when Ce accounts for 0.030 percent.

Originality/value

This paper usefully investigates the effects of the RE cerium (Ce), on the microstructures and creep properties of Sn-Ag-Cu solder alloys, optimizing the quantity of Ce in the Sn-Ag-Cu solder alloy through a thermodynamic method and by creep-rupture life testing.

Details

Soldering & Surface Mount Technology, vol. 22 no. 2
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 25 February 2020

Lucas Silvestre de Carvalho, Nelson Oliveira Stefanelli, Lilian Carolina Viana, Diogo de Siqueira Camargo Vasconcelos and Bruno Garcia Oliveira

This paper aims to investigate the main associations between research regarding innovation and green supply chain management (GSCM).

Abstract

Purpose

This paper aims to investigate the main associations between research regarding innovation and green supply chain management (GSCM).

Design/methodology/approach

For this the study sought to (1) present the most cited authors in the area; (2) demonstrate the main localities that develop research with this focus; (3) list the main journals with the published research on the themes. The methodology used was a bibliometric survey using the Scopus database as the data source. The VOSviewer® software was used to perform the analysis of the database from the respective DOI® of each article.

Findings

As results of the research, it is possible to demonstrate the existence of an agglomeration of countries that are interrelated in the development of research on these themes, especially China, the United States and the United Kingdom as the main foundations of this center.

Originality/value

This paper evidences the direction of scientific research within the analyzed area, demonstrating where there is convergence for innovation in actions related to GSCM. This guidance may demonstrate possible existing and unexplored gaps so that researchers can direct future research or check gaps to be filled by the development of new processes.

Details

Management of Environmental Quality: An International Journal, vol. 31 no. 2
Type: Research Article
ISSN: 1477-7835

Keywords

Book part
Publication date: 15 January 2010

Moshe Ben-Akiva

Purpose: This chapter introduces a choice modeling framework that explicitly represents the planning and action stages of the choice process.Methodology: A discussion of…

Abstract

Purpose: This chapter introduces a choice modeling framework that explicitly represents the planning and action stages of the choice process.

Methodology: A discussion of evidence from behavioral research is followed by the development of a discrete choice modeling framework with explicit planning and action submodels. The plan/action choice model is formulated for both static and dynamic contexts; where the latter is based on the Hidden Markov Model. Plans are often unobservable and are treated as latent variables in model estimation using observed actions.

Implications: By modeling the interactions between the planning and action stages, we are able to incorporate richer specifications in choice models with better predictive and policy analysis capabilities. The applications of this research in areas such as driving behavior, route choice, and mode choice demonstrate the advantages of the plan/action model in comparison to a “black box” choice model in terms of improved microsimulations of behaviors that better represent real-life situations. As such, the outcomes of this chapter are relevant to researchers and policy analysts.

Details

Choice Modelling: The State-of-the-art and The State-of-practice
Type: Book
ISBN: 978-1-84950-773-8

Article
Publication date: 7 August 2017

Yuchen Lin, Yangbo Song and Jinsong Tan

As an important participant in capital market, institutional investors play a principal role in improving corporate governance. Most existing studies have focused on…

Abstract

Purpose

As an important participant in capital market, institutional investors play a principal role in improving corporate governance. Most existing studies have focused on institutional ownership and its economic consequences. Nevertheless, they have not provided sufficient insight on the governance behavior of institutional investors as well as the underlying incentive mechanism. This paper aims to analyze the governance role of institutional investors in information disclosure and provide related evidence.

Design/methodology/approach

The authors propose a novel theory to analyze the institutional investors’ behavior of active governance and shows that such behavior significantly improves the quality of corporate information disclosure. The authors then conduct an empirical test by using the hand-collected data of institutional investors’ corporate visits during 2009-2014 in ChiNext.

Findings

This paper finds that the firms visited by institutional investors are more likely to have a greater tendency of disclosing more information than the firms that have never been visited. In particular, a higher frequency of visits or a larger number of participating institutional investors leads to a higher degree of disclosure. Consistent with the notion that on-site visits endow institutional investors with more frequent and active interaction with the firms, the authors find that the results are stronger for firms which are visited on-site, when compared with other information acquisition activities such as online meetings, conference calls and investor meetings. In addition, the effect of a site visit is greater when the site visit is conducted by securities companies or funds rather than insurance companies or QFIIs. Finally, the test of the direction of causality suggests that visits conducted by institutional investors leads to more information disclosure, rather than the reverse. Collectively, these results show that institutional investors’ participation enhances corporate information disclosure.

Originality/value

This paper explores the internal mechanism that institutional investors affect corporate governance by improving information disclosure through their corporate visits. This is the first study to investigate the influence of institutional investors’ corporate visits and their economic consequences.

Details

Nankai Business Review International, vol. 8 no. 3
Type: Research Article
ISSN: 2040-8749

Keywords

1 – 10 of over 2000