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Open Access
Article
Publication date: 5 February 2024

Krištof Kovačič, Jurij Gregorc and Božidar Šarler

This study aims to develop an experimentally validated three-dimensional numerical model for predicting different flow patterns produced with a gas dynamic virtual nozzle (GDVN).

Abstract

Purpose

This study aims to develop an experimentally validated three-dimensional numerical model for predicting different flow patterns produced with a gas dynamic virtual nozzle (GDVN).

Design/methodology/approach

The physical model is posed in the mixture formulation and copes with the unsteady, incompressible, isothermal, Newtonian, low turbulent two-phase flow. The computational fluid dynamics numerical solution is based on the half-space finite volume discretisation. The geo-reconstruct volume-of-fluid scheme tracks the interphase boundary between the gas and the liquid. To ensure numerical stability in the transition regime and adequately account for turbulent behaviour, the k-ω shear stress transport turbulence model is used. The model is validated by comparison with the experimental measurements on a vertical, downward-positioned GDVN configuration. Three different combinations of air and water volumetric flow rates have been solved numerically in the range of Reynolds numbers for airflow 1,009–2,596 and water 61–133, respectively, at Weber numbers 1.2–6.2.

Findings

The half-space symmetry allows the numerical reconstruction of the dripping, jetting and indication of the whipping mode. The kinetic energy transfer from the gas to the liquid is analysed, and locations with locally increased gas kinetic energy are observed. The calculated jet shapes reasonably well match the experimentally obtained high-speed camera videos.

Practical implications

The model is used for the virtual studies of new GDVN nozzle designs and optimisation of their operation.

Originality/value

To the best of the authors’ knowledge, the developed model numerically reconstructs all three GDVN flow regimes for the first time.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 34 no. 4
Type: Research Article
ISSN: 0961-5539

Keywords

Open Access
Article
Publication date: 18 November 2021

Joanna Grochowalska, Piotr Jaworski, Łukasz Jan Kapusta and Jerzy Kowalski

In the cylinders of a marine diesel engine, self-ignition occurs in a very short time after the fuel injection into the combustion chamber. Therefore, this paper aims to develop a…

Abstract

Purpose

In the cylinders of a marine diesel engine, self-ignition occurs in a very short time after the fuel injection into the combustion chamber. Therefore, this paper aims to develop a model of diesel fuel spray for the early stage of fuel spray in the marine diesel engine. The main technical aspects such as nozzle diameter of the marine engine injector and backpressure in the combustion chamber were taken into consideration.

Design/methodology/approach

In this paper, laboratory experimental studies were carried out to determine parameters of fuel spray in an early stage of injection in the marine diesel engine. The optical measuring Mie scattering technique was used to record the fuel injection process. The working space was a constant volume chamber. The backpressure parameters in the constant volume chamber were the same as during the operation of the marine diesel engine. Based on the experimental studies and important Hiroyasu and Arai models of fuel spray presented in literature was proposed new model of fuel spray parameters for marine diesel injectors.

Findings

In this paper, the proposed new model of the two main parameters described fuel spray evolution”: new model of spray tip penetration (STP) and spray cone angle (SCA). New model propagation of fuel STP in time was included the influence of nozzle diameter and backpressure. The proposed model has a lower error, about 15%–34%, than the model of Hiroyasu and Arai. Moreover, a new model of the evolution over time of the SCA is developed.

Research limitations/implications

In the future research of fuel spray process must be taken influence of the fuel temperature. Diesel fuel has a different density and viscosity in dependence of fuel temperature. Therefore are predicted of the expansion about influence of fuel temperature, new model of fuel spray for a marine diesel engine. The main limitations occurring in the research are not possible to carry out the research while real operation marine diesel engine.

Originality/value

An experimental test was carried out for a real fuel injector of a marine diesel engine. Design parameters and fuel injection parameters were selected on the basis of the actual one. In the literature, SCA is defined as a constant parameter for the specific preliminary data. A new model for the early stage of fuel spray of SCA propagation in time has been proposed. The early stage of fuel spray is especially important, because in this time comes in there to fuel self-ignition.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 32 no. 7
Type: Research Article
ISSN: 0961-5539

Keywords

Open Access
Article
Publication date: 14 May 2019

Yuqiang Wang, Yuguang Wei, Hua Shi, Xinyu Liu, Liyuan Feng and Pan Shang

The purpose of this paper is to study the unit train make-up scheme for loaded direction in the heavy haul railway.

Abstract

Purpose

The purpose of this paper is to study the unit train make-up scheme for loaded direction in the heavy haul railway.

Design/methodology/approach

A 0-1 nonlinear integer programming model with the aim of minimizing the idling period between actual train arrival time and expected train arrival time for all loaded unit trains are proposed.

Findings

The proposed model is applied into a case study based on Daqin heavy haul railway. Results show that the proposed model can offer operators an optimal unit train make-up scheme for loaded direction in heavy haul railway.

Originality/value

The proposed model can offer operators an optimal unit train make-up scheme for loaded direction in heavy haul railway.

Details

Smart and Resilient Transportation, vol. 1 no. 1
Type: Research Article
ISSN: 2632-0487

Keywords

Open Access
Article
Publication date: 5 August 2021

Kishore Thomas John

The pervasive impact of the COVID-19 virus on the food services sector in India has created conditions for fundamentally altering the structure of the industry. This paper offers…

9816

Abstract

Purpose

The pervasive impact of the COVID-19 virus on the food services sector in India has created conditions for fundamentally altering the structure of the industry. This paper offers a nuanced evaluation of the transfiguration of the market, explaining descriptive views supported by numerous secondary data sources.

Design/methodology/approach

This is a self-driven study grounded in secondary data. Qualitative and quantitative assessments are assimilated from credible market research reports of multiple agencies in the Indian context, as well as news developments during the pandemic period.

Findings

Digitally pivoted platforms such as cloud kitchens and delivery aggregators will eclipse all other formats due to the potential long-term prevalence of the COVID-19 virus. These formats would rise to a dominant position in the Indian food services sector in the coming decade.

Research limitations/implications

This study is entirely driven by secondary data due to the inherent difficulties of collecting sizeable and good quality primary data as a result of the lengthy and stringent lockdowns imposed across India. Future studies should consider collecting consumer responses to get a better picture of changing dining habits in the post-pandemic scenario.

Practical implications

The dynamic and evolving food services in India, catalyzed by the Internet and digital technologies will help academicians study the long-term implications of this change, and how it would impact society at large. The paper provides a rich body of contemporary data and analysis in the food services sphere.

Social implications

The COVID-19 pandemic and its long-term persistence would dramatically alter food service consumption across India. This will not only change how the industry is structured, but will reshape how food is consumed into the future.

Originality/value

The study is a holistic examination of the relationship between the coronavirus pandemic and the food services industry in India. The macro perspectives aided by news coverage and industry research would help generate potential research questions on its own merits.

Details

International Hospitality Review, vol. 37 no. 1
Type: Research Article
ISSN: 2516-8142

Keywords

Open Access
Book part
Publication date: 17 August 2021

Mike Hynes

Abstract

Details

The Social, Cultural and Environmental Costs of Hyper-Connectivity: Sleeping Through the Revolution
Type: Book
ISBN: 978-1-83909-976-2

Open Access
Article
Publication date: 12 September 2016

Peter Antony Singleton

The purpose of this paper is to assert the link between the process of EU accession, the consolidation of democratic processes and the improvement of economic and tourism…

2364

Abstract

Purpose

The purpose of this paper is to assert the link between the process of EU accession, the consolidation of democratic processes and the improvement of economic and tourism infrastructure to incoming tourism flows.

Design/methodology/approach

The methodology of this paper involves explanation of an analysis exploring links between governmental systems and the order necessary for economic development and tourism. The argument is supported by the recent history of tourism development in three countries, two within the EU and one outside.

Findings

Accession to the EU (especially in the case of Eastern European countries) constitutes a way to emulate the democratic freedoms and greater economic prosperity of existing EU member states. Tourism is one of the areas of economy that benefits from the stability and growth EU membership can bring. Accession to the EU has had beneficial effects for acceding in terms of political stability and tourism growth.

Originality/value

The opportunities that EU membership can bring to tourism development for example (also strategies to exploit these opportunities) depend to a large degree on the international relations between the EU and its rivals. The extent to which tourism demands ebb and flow is governed by a range of factors, but the issues of conflict and security are game breakers. Understanding the factors and trends involved in the peaceful resolution of conflict (democratic model) or use of force to resolve conflict (military model) is key in the analysis of future tourism opportunities.

Details

Journal of Tourism Futures, vol. 2 no. 2
Type: Research Article
ISSN: 2055-5911

Keywords

Abstract

Details

Sameness and Repetition in Contemporary Media Culture
Type: Book
ISBN: 978-1-80455-955-0

Open Access
Book part
Publication date: 4 June 2021

Julia Slupska and Leonie Maria Tanczer

Technology-facilitated abuse, so-called “tech abuse,” through phones, trackers, and other emerging innovations, has a substantial impact on the nature of intimate partner violence…

Abstract

Technology-facilitated abuse, so-called “tech abuse,” through phones, trackers, and other emerging innovations, has a substantial impact on the nature of intimate partner violence (IPV). The current chapter examines the risks and harms posed to IPV victims/survivors from the burgeoning Internet of Things (IoT) environment. IoT systems are understood as “smart” devices such as conventional household appliances that are connected to the internet. Interdependencies between different products together with the devices' enhanced functionalities offer opportunities for coercion and control. Across the chapter, we use the example of IoT to showcase how and why tech abuse is a socio-technological issue and requires not only human-centered (i.e., societal) but also cybersecurity (i.e., technical) responses. We apply the method of “threat modeling,” which is a process used to investigate potential cybersecurity attacks, to shift the conventional technical focus from the risks to systems toward risks to people. Through the analysis of a smart lock, we highlight insufficiently designed IoT privacy and security features and uncover how seemingly neutral design decisions can constrain, shape, and facilitate coercive and controlling behaviors.

Details

The Emerald International Handbook of Technology-Facilitated Violence and Abuse
Type: Book
ISBN: 978-1-83982-849-2

Keywords

Open Access
Book part
Publication date: 4 May 2018

Zulnazri and Sulhatun

Purpose – This purpose of the research is to investigate the process of manufacturing LDPE recycle thermoplastic composites with reinforcement oil palm empty fruit bunch (OPEFB…

Abstract

Purpose – This purpose of the research is to investigate the process of manufacturing LDPE recycle thermoplastic composites with reinforcement oil palm empty fruit bunch (OPEFB) biomass microfillers.

Design/Methodology/Approach – Methods of physical and chemical modification of OPEFB fibers into the LDPE matrix and the addition of some compatibilizer such as MAPE and xylene process through melt blending can improve mechanical properties, electrical properties, biodegradability, and improve the morphology of composites.

Research Limitations/Implications – These composites are prepared by the following matrix ratio: filler (70:30)% and filler size (63, 75, 90, and 106) μm. The LDPE plastic is crushed to a size of 0.5–1 cm, then pressed with hot press free heating for 5 min and with a pressure of 10 min at 145 °C. Based on the characterization obtained, the tensile strength and the high impact on the use of 106 μm filler is 13.86 MPa and 3,542.6 J/m2, and thermal stability indicates the degradation temperature (T0) 497.83 °C. FT-IR analysis shows the presence of functional groups of cellulose and lignin molecules derived from TKKS collected in the composite.

Practical Implications – Based on the characterization obtained, this composite can be applied as furniture material and vehicle dashboard.

Originality/Value – Composites obtained from recycle of LDPPE plastics waste has some advantages such as good compatibility and high tensile strength. This composite used the OPEFB filler whose size is in micrometer, and so this product is different from other products.

Details

Proceedings of MICoMS 2017
Type: Book
ISBN:

Keywords

Open Access
Article
Publication date: 8 January 2021

Sanjeev Singh, Sruti Singha Roy and Kirti Sundar Sahu

Throughout history, pandemics have played a significant role in reshaping human civilizations through mortalities, morbidities, economic losses and other catastrophic…

1019

Abstract

Purpose

Throughout history, pandemics have played a significant role in reshaping human civilizations through mortalities, morbidities, economic losses and other catastrophic consequences. The present COVID-19 pandemic has brought the world to its knees resulting in overstretched healthcare systems, increased health inequalities and disruptions to people’s right to health including life-saving routine immunization programs across the world.

Design/methodology/approach

This is a commentary paper.

Findings

Immunization remains one of the most successful, safe, cost-effective and proven fundamental disease prevention measures in the history of public health. However, the COVID-19 pandemic has effectively thrown the world's immunization practices out of gear, depriving approximately 80 million infants, in rich and poor countries alike, at risk of triggering a resurgence of vaccine-preventable diseases such as diphtheria, measles and polio. It is estimated that each COVID-19 death averted by suspending immunization sessions in Africa could lead to 29-347 future deaths due to other diseases including measles, yellow fever, polio, meningitis, pneumonia and diarrhoea.

Originality/value

The value of implementing robust immunization policies cannot be underestimated. Risks associated with postponing immunization services and the fact that COVID-19 is now an integral part of human civilization have resulted in several countries making special efforts to continue their immunization services. However, critical precautionary measures are warranted to prevent COVID-19 among healthcare service providers, facilitators, caregivers and children during the immunization sessions.

Details

Journal of Health Research, vol. 35 no. 3
Type: Research Article
ISSN: 0857-4421

Keywords

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