Search results

1 – 10 of 11
Per page
102050
Citations:
Loading...
Access Restricted. View access options
Article
Publication date: 13 September 2018

Haiming Huang and Yumeng Hu

With the continuous increase of space activities and insight into space exploration, the velocity of near space hypersonic vehicles becomes higher and higher, which leads to the…

86

Abstract

Purpose

With the continuous increase of space activities and insight into space exploration, the velocity of near space hypersonic vehicles becomes higher and higher, which leads to the aerothermodynamic phenomenon getting worse around a vehicle; therefore, the exploration of numerical scheme applicability is essential for hypersonic flow simulations.

Design/methodology/approach

The implicit finite volume schemes are derived from axisymmetric Navier–Stokes equations for chemical equilibrium flow and programmed in Fortran. Taking the atmosphere at 30 km as an example, the performance of spatial discretization schemes such as AUSMPW and AUSMPW+ are analyzed in a range of Mach numbers from 17 to 32.

Findings

The AUSMPW scheme appears pressure jump near the stagnation if the Mach number is over 18, but AUSMPW+ scheme shows better performance in comparison.

Originality/value

This study will help the aerothermodynamic design in near space hypersonic vehicles.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 28 no. 8
Type: Research Article
ISSN: 0961-5539

Keywords

Access Restricted. View access options
Article
Publication date: 5 June 2017

Yumeng Hu, Haiming Huang and Zimao Zhang

The purpose of this paper is to explore the characteristics of hypersonic flow past a blunt body.

398

Abstract

Purpose

The purpose of this paper is to explore the characteristics of hypersonic flow past a blunt body.

Design/methodology/approach

The implicit finite volume schemes are derived from axisymmetric Navier–Stokes equations by means of AUSM+ and LU-SGS methods, and programmed in FORTRAN. Based on the verified result that a 2D axisymmetric chemical equilibrium flow has a good agreement with the literature, the characteristics of hypersonic flow past a sphere are simulated by using four different models which involve four factors, namely, viscous, inviscid, equilibrium and calorically perfect gas.

Findings

Compared with the calorically perfect gas under hypervelocity condition, the shock wave of the equilibrium gas is more close to the blunt body, gas density and pressure become bigger, but gas temperature is lower due to the effect of real gas. Viscous effects are not obvious in the calculations of the equilibrium gas or the calorically perfect gas. In a word, the model of equilibrium gas is more suitable for hypersonic flow and the calculation of viscous flow has a smaller error.

Originality/value

The computer codes are developed to simulate the characteristics of hypersonic flows, and this study will be helpful for the design of the thermal protection system in hypersonic vehicles.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 27 no. 6
Type: Research Article
ISSN: 0961-5539

Keywords

Access Restricted. View access options
Article
Publication date: 10 September 2021

Yucheng Zhang, Zhongwei Hou, Xingxing Zhou, Yumeng Yue, Siqi Liu, XiaoXiao Jiang and Ling Li

Despite recent organizational behavior studies have witnessed considerable progress in abusive supervision research; some demerits for both theory and methodology still remain in…

694

Abstract

Purpose

Despite recent organizational behavior studies have witnessed considerable progress in abusive supervision research; some demerits for both theory and methodology still remain in the past years. To clarify the current state of knowledge in the field, this study aims to analyze the current state of theories and methods on abusive supervision and provides a detailed future research agenda.

Design/methodology/approach

This paper conducted a literature review for both theory and methodology of the abusive supervision research using a content analysis of 134 publications.

Findings

For the theory part, this paper summarized the theories that had been applied to explain the relationship between abusive supervision and its consequences as well as antecedents. For the methodology part, this paper outlined some critical issues regarding country of origin, research design, measurement, analysis strategy and also summarized with a discussion of the relationship between methodological issues and article impact. Finally, this paper concluded by presenting an agenda for future abusive supervision research regarding both theory and methodology.

Originality/value

First, this paper summarizes the main theories, antecedents and consequences often used in abusive supervision research to allow scholars to carry out theoretically driven research investigating abusive supervision in the future. Second, through a content analysis of the methods sections of abusive supervision research in the samples (i.e. country of origin, research design, measurement and analytical procedures), this paper identified the potential reasons underlying the inconsistency in the conclusions of abusive supervision research and provide some guidance for future empirical studies. Third, based on the qualitative review, this paper provides an agenda for future research investigating abusive supervision by developing a content-specific theoretical framework to benchmark abusive supervision research against other research related to leadership and offers an accurate response to scholars’ criticisms of abusive supervision research.

Details

Chinese Management Studies, vol. 16 no. 3
Type: Research Article
ISSN: 1750-614X

Keywords

Available. Open Access. Open Access
Article
Publication date: 2 June 2023

Junru Zhang, Yumeng Liu and Bo Yan

This study aims to research the large cross-section tunnel stability evaluation method corrected after considering the thickness-span ratio.

348

Abstract

Purpose

This study aims to research the large cross-section tunnel stability evaluation method corrected after considering the thickness-span ratio.

Design/methodology/approach

First, taking the Liuyuan Tunnel of Huanggang-Huangmei High-Speed Railway as an example and taking deflection of the third principal stress of the surrounding rock at a vault after tunnel excavation as the criterion, the critical buried depth of the large section tunnel was determined. Then, the strength reduction method was employed to calculate the tunnel safety factor under different rock classes and thickness-span ratios, and mathematical statistics was conducted to identify the relationships of the tunnel safety factor with the thickness-span ratio and the basic quality (BQ) index of the rock for different rock classes. Finally, the influences of thickness-span ratio, groundwater, initial stress of rock and structural attitude factors were considered to obtain the corrected BQ, based on which the stability of a large cross-section tunnel with a depth of more than 100 m during mechanized operation was analyzed. This evaluation method was then applied to Liuyuan Tunnel and Cimushan No. 2 Tunnel of Chongqing Urban Expressway for verification.

Findings

This study shows that under different rock classes, the tunnel safety factor is a strict power function of the thickness-span ratio, while a linear function of the BQ to some extent. It is more suitable to use the corrected BQ as a quantitative index to evaluate tunnel stability according to the actual conditions of the site.

Originality/value

The existing industry standards do not consider the influence of buried depth and span in the evaluation of tunnel stability. The stability evaluation method of large section tunnel considering the correction of overburden span ratio proposed in this paper achieves higher accuracy for the stability evaluation of surrounding rock in a full or large-section mechanized excavation of double line high-speed railway tunnels.

Access Restricted. View access options
Article
Publication date: 8 November 2024

Yongliang Wang, Yifeng Duan, Yanpei Song and Yumeng Du

Supercritical CO2 (SC–CO2) fracturing is a potential technology that creates a complex fracturing fracture network to improve reservoir permeability. SC–CO2-driven intersections…

42

Abstract

Purpose

Supercritical CO2 (SC–CO2) fracturing is a potential technology that creates a complex fracturing fracture network to improve reservoir permeability. SC–CO2-driven intersections of the fracturing fracture network are influenced by some key factors, including the disturbances generated form natural fractures, adjacent multi-wells and adjacent fractures, which increase the challenges in evaluation, control and optimization of the SC–CO2 fracturing fracture networks. If the evaluation of the fracture network is not accurate and effective, the risk of oil and gas development will increase due to the microseismicity induced by multi-well SC–CO2 fracturing, which makes it challenging to control the on-site engineering practices.

Design/methodology/approach

The numerical models considering the thermal-hydro-mechanical coupling effect in multi-well SC–CO2 fracturing were established, and the typical cases considering naturally fracture and multi-wells were proposed to investigate the intersections and connections of fracturing fracture network, shear stress shadows and induced microseismic events. The quantitative results from the typical cases, such as fracture length, volume, fluid rate, pore pressure and the maximum and accumulated magnitudes of induced microseismic events, were derived.

Findings

In naturally fractured reservoirs, SC–CO2 fracturing fractures will deflect and propagate along the natural fractures, eventually intersect and connect with fractures from other wells. The quantitative results indicate that SC–CO2 fracturing in naturally fractured reservoirs produces larger fractures than the slick water as fracturing fluid, due to the ability of SC–CO2 to connect macroscopic and microscopic fractures. Compared with slick water fracturing, SC–CO2 fracturing can increase the length of fractures, but it will not increase microseismic events; therefore, SC–CO2 fracturing can improve fracturing efficiency and increase productivity, but it may not simultaneously lead to additional microseismic events.

Originality/value

The results of this study on the multi-well SC–CO2 fracturing may provide references for the fracturing design of deep oil and gas resource extraction, and provide some beneficial supports for the induced microseismic event disasters, promoting the next step of engineering application of multi-well SC–CO2 fracturing.

Access Restricted. View access options
Article
Publication date: 22 February 2024

Yumeng Feng, Weisong Mu, Yue Li, Tianqi Liu and Jianying Feng

For a better understanding of the preferences and differences of young consumers in emerging wine markets, this study aims to propose a clustering method to segment the super-new…

54

Abstract

Purpose

For a better understanding of the preferences and differences of young consumers in emerging wine markets, this study aims to propose a clustering method to segment the super-new generation wine consumers based on their sensitivity to wine brand, origin and price and then conduct user profiles for segmented consumer groups from the perspectives of demographic attributes, eating habits and wine sensory attribute preferences.

Design/methodology/approach

We first proposed a consumer clustering perspective based on their sensitivity to wine brand, origin and price and then conducted an adaptive density peak and label propagation layer-by-layer (ADPLP) clustering algorithm to segment consumers, which improved the issues of wrong centers' selection and inaccurate classification of remaining sample points for traditional DPC (DPeak clustering algorithm). Then, we built a consumer profile system from the perspectives of demographic attributes, eating habits and wine sensory attribute preferences for segmented consumer groups.

Findings

In this study, 10 typical public datasets and 6 basic test algorithms are used to evaluate the proposed method, and the results showed that the ADPLP algorithm was optimal or suboptimal on 10 datasets with accuracy above 0.78. The average improvement in accuracy over the base DPC algorithm is 0.184. As an outcome of the wine consumer profiles, sensitive consumers prefer wines with medium prices of 100–400 CNY and more personalized brands and origins, while casual consumers are fond of popular brands, popular origins and low prices within 50 CNY. The wine sensory attributes preferred by super-new generation consumers are red, semi-dry, semi-sweet, still, fresh tasting, fruity, floral and low acid.

Practical implications

Young Chinese consumers are the main driver of wine consumption in the future. This paper provides a tool for decision-makers and marketers to identify the preferences of young consumers quickly which is meaningful and helpful for wine marketing.

Originality/value

In this study, the ADPLP algorithm was introduced for the first time. Subsequently, the user profile label system was constructed for segmented consumers to highlight their characteristics and demand partiality from three aspects: demographic characteristics, consumers' eating habits and consumers' preferences for wine attributes. Moreover, the ADPLP algorithm can be considered for user profiles on other alcoholic products.

Details

Kybernetes, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0368-492X

Keywords

Access Restricted. View access options
Article
Publication date: 31 October 2023

Yumeng Yue, Nate Zettna, Shuoxin Cheng and Helena Nguyen

In many contemporary service organizations, service teams or service units are the main engines used to deliver key services to customers, client or patients. However, it remains…

542

Abstract

Purpose

In many contemporary service organizations, service teams or service units are the main engines used to deliver key services to customers, client or patients. However, it remains unclear how teamwork mechanisms (i.e. the ways team members work together) influence customer service outcomes, and whether these relationships vary across different service contexts. To advance knowledge on the nature of teamwork in service teams and to set an agenda for further work in this area, there is a need to integrate and synthesize findings across the diverse literature on service teamwork. This paper aims to discuss the aforementioned objectives.

Design/methodology/approach

Using a meta-analytic approach, the authors analyzed a substantial pool of relevant effect sizes (a total of 372 effect sizes from 82 studies, with 14,291 service teams/units) to examine the effects of affective, behavioral, cognitive, motivational as well as perceptual teamwork mechanisms on customer service outcomes. The authors also investigated two key service context variables (service climate and service type) as boundary conditions on these effects.

Findings

The authors found that cognitive teamwork mechanisms were more strongly positively associated with customer evaluative outcomes than other mechanisms, whereas motivational and perceptual teamwork mechanisms had stronger associations with financial outcomes. Further, four of the five teamwork mechanisms demonstrated stronger correlations under a high service climate. The strength of the correlations between the teamwork mechanisms and customer service outcomes also exhibited different patterns when considered for different service types.

Research limitations/implications

As with all meta-analysis, the quality of the primary studies influences the quality of the insights obtained from summarized effects. As most studies are cross-sectional design, the relationships examined in this paper cannot be interpreted causally. The authors cannot rule out the possibility of reverse causality, for example, reciprocal effects of customer service outcomes on teamwork dynamics due to the reciprocal feedback loop between customers and service providers.

Practical implications

The results hold important practical implications for enhancing customer evaluation and financial performance. First, the overall findings point to the need for employers to emphasize on certain types of teamwork training in order to encourage employee collaboration within service teams. For instance, service organizations could plan team building activities for service teams to promote trust, strengthen interpersonal bonds and improve problem-solving.

Originality/value

The results of this study provide an integration of previous research on service teamwork and fill two important gaps in the knowledge: (1) which aspect of teamwork is more important in determining customer service outcomes? And (2) does the effect of teamwork on customer service outcomes differ across different service contexts?

Details

Journal of Service Management, vol. 34 no. 5
Type: Research Article
ISSN: 1757-5818

Keywords

Available. Open Access. Open Access
Article
Publication date: 17 June 2022

Songqing Li, Xuexi Huo, Ruishi Si, Xueqian Zhang, Yumeng Yao and Li Dong

Climatic changes caused by greenhouse gases (GHGs) emissions are an urgent challenge for all regions around the globe while the livestock sector is an important source of GHGs…

1559

Abstract

Purpose

Climatic changes caused by greenhouse gases (GHGs) emissions are an urgent challenge for all regions around the globe while the livestock sector is an important source of GHGs emissions. The adoption of low-carbon manure treatment technology (LMTT) by farmers is emerging as an effective remedy to neutralize the carbon emissions of livestock. This paper aims to incorporate environmental literacy and social norms into the analysis framework, with the aim of exploring the impact of environmental literacy and social norms on farmers' adoption of LMTT and finally reduce GHGs emission and climate effects.

Design/methodology/approach

This research survey is conducted in Hebei, Henan and Hubei provinces of China. First, this research measures environmental literacy from environmental cognition, skill and responsibility and describes social norms from descriptive and imperative social norms. Second, this paper explores the influence of environmental literacy and social norms on the adoption of LMTT by farmers using the logit model. Third, Logit model's instrumental approach, i.e. IV-Logit, is applied to address the simultaneous biases between environmental skill and farmers’ LMTT adoption. Finally, the research used a moderating model to analyze feasible paths of environmental literacy and social norms that impact the adoption of LMTT by farmers.

Findings

The results showed that environmental literacy and social norms significantly and positively affect the adoption of LMTT by farmers. In particular, the effects of environmental literacy on the adoption of LMTT by farmers are mainly contributed by environmental skill and responsibility. The enhancement of social norms on the adoption of LMTT by farmers is mainly due to the leading role of imperative social norms. Meanwhile, if the endogeneity caused by the reverse effect between environmental skill and farmers’ LMTT adoption is dealt with, the role of environmental skill will be weakened. Additionally, LMTT technologies consist of energy and resource technologies. Compared to energy technology, social norms have a more substantial moderating effect on environmental literacy, affecting the adoption of farmer resource technology.

Originality/value

To the best of the authors’ knowledge, a novel attempt is made to examine the effects of environmental literacy and social norms on the adoption of LMTT by farmers, with the objective of identifying more effective factors to increase the intensity of LMTT adoption by farmers.

Details

International Journal of Climate Change Strategies and Management, vol. 16 no. 4
Type: Research Article
ISSN: 1756-8692

Keywords

Access Restricted. View access options
Article
Publication date: 3 March 2020

Vitus Mwinteribo Tabie, Chong Li, Wang Saifu, Jianwei Li and Xiaojing Xu

This paper aims to present a broad review of near-a titanium alloys for high-temperature applications.

1549

Abstract

Purpose

This paper aims to present a broad review of near-a titanium alloys for high-temperature applications.

Design/methodology/approach

Following a brief introduction of titanium (Ti) alloys, this paper considers the near-α group of Ti alloys, which are the most popular high-temperature Ti alloys developed for a high-temperature application, particularly in compressor disc and blades in aero-engines. The paper is relied on literature within the past decade to discuss phase stability and microstructural effect of alloying elements, plastic deformation and reinforcements used in the development of these alloys.

Findings

The near-a Ti alloys show high potential for high-temperature applications, and many researchers have explored the incorporation of TiC, TiB SiC, Y2O3, La2O3 and Al2O3 reinforcements for improved mechanical properties. Rolling, extrusion, forging and some severe plastic deformation (SPD) techniques, as well as heat treatment methods, have also been explored extensively. There is, however, a paucity of information on SiC, Y2O3 and carbon nanotube reinforcements and their combinations for improved mechanical properties. Information on some SPD techniques such as cyclic extrusion compression, multiaxial compression/forging and repeated corrugation and straightening for this class of alloys is also limited.

Originality/value

This paper provides a topical, technical insight into developments in near-a Ti alloys using literature from within the past decade. It also outlines the future developments of this class of Ti alloys.

Details

Aircraft Engineering and Aerospace Technology, vol. 92 no. 4
Type: Research Article
ISSN: 1748-8842

Keywords

Access Restricted. View access options
Article
Publication date: 27 July 2021

Zhihai Yang, Ning Yin, Amin William Mugera and Yumeng Wang

This paper analysed survey data of 715 rice-producing households in China to assess the determinants of adoption of five mutually exclusive soil conservation practices (SCPs) and…

430

Abstract

Purpose

This paper analysed survey data of 715 rice-producing households in China to assess the determinants of adoption of five mutually exclusive soil conservation practices (SCPs) and their impact on rice yield and chemical fertiliser use.

Design/methodology/approach

The multinomial endogenous treatment effects model was used to account for selection bias and endogeneity arising from both observed and unobserved heterogeneity.

Findings

Farms that adopted SCPs as a package experienced an increase in rice yield and decrease in chemical fertiliser use. Adoption of SCPs as a package led to a 12.0% increase in yield and 15.2% decrease in chemical fertiliser use; these results have policy implications for the non-point source pollution control in the agricultural sector. In contrast, adoption of straw retention only significantly reduced yield by 4.9% and increased chemical fertiliser use by 18.1%.

Originality/value

The authors evaluate and compare multi-type of SCPs, such as straw retention, deep tillage and use of organic fertiliser, separately or in combination, and their impacts on smallholder farmers’ rice yield and chemical fertiliser usage.

Details

China Agricultural Economic Review, vol. 13 no. 4
Type: Research Article
ISSN: 1756-137X

Keywords

1 – 10 of 11
Per page
102050