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Expert briefing
Publication date: 29 January 2024

Markets have largely taken Red Sea trade disruption in their stride. Increased non-OPEC supply is expected this year, leaving the major uncertainty around the impact on demand of…

Details

DOI: 10.1108/OXAN-DB284853

ISSN: 2633-304X

Keywords

Geographic
Topical
Open Access
Article
Publication date: 11 January 2023

Antonio Focacci

The purpose of this stud is to analyze the financialization effect on oil prices.

Abstract

Purpose

The purpose of this stud is to analyze the financialization effect on oil prices.

Design/methodology/approach

This study applied the technique of multibreak point analysis with Bai and Perron test plus VAR methodology.

Findings

Findings revealed that there was no effect on oil prices.

Originality/value

To the best of the author’s knowledge, this is the first paper combining the multibreakpoint analysis with VAR for the period analyzed in the present work.

Open Access
Article
Publication date: 19 March 2024

Chun Tian, Gengwei Zhai, Mengling Wu, Jiajun Zhou and Yaojie Li

In response to the problem of insufficient traction/braking adhesion force caused by the existence of the third-body medium on the rail surface, this study aims to analyze the…

Abstract

Purpose

In response to the problem of insufficient traction/braking adhesion force caused by the existence of the third-body medium on the rail surface, this study aims to analyze the utilization of wheel-rail adhesion coefficient under different medium conditions and propose relevant measures for reasonable and optimized utilization of adhesion to ensure the traction/braking performance and operation safety of trains.

Design/methodology/approach

Based on the PLS-160 wheel-rail adhesion simulation test rig, the study investigates the variation patterns of maximum utilized adhesion characteristics on the rail surface under different conditions of small creepage and large slip. Through statistical analysis of multiple sets of experimental data, the statistical distribution patterns of maximum utilized adhesion on the rail surface are obtained, and a method for analyzing wheel-rail adhesion redundancy based on normal distribution is proposed. The study analyzes the utilization of traction/braking adhesion, as well as adhesion redundancy, for different medium under small creepage and large slip conditions. Based on these findings, relevant measures for the reasonable and optimized utilization of adhesion are derived.

Findings

When the third-body medium exists on the rail surface, the train should adopt the low-level service braking to avoid the braking skidding by extending the braking distance. Compared with the current adhesion control strategy of small creepage, adopting appropriate strategies to control the train’s adhesion coefficient near the second peak point of the adhesion coefficient-slip ratio curve in large slip can effectively improve the traction/braking adhesion redundancy and the upper limit of adhesion utilization, thereby ensuring the traction/braking performance and operation safety of the train.

Originality/value

Most existing studies focus on the wheel-rail adhesion coefficient values and variation patterns under different medium conditions, without considering whether the rail surface with different medium can provide sufficient traction/braking utilized adhesion coefficient for the train. Therefore, there is a risk of traction overspeeding/braking skidding. This study analyzes whether the rail surface with different medium can provide sufficient traction/braking utilized adhesion coefficient for the train and whether there is redundancy. Based on these findings, relevant measures for the reasonable and optimized utilization of adhesion are derived to further ensure operation safety of the train.

Details

Railway Sciences, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 2755-0907

Keywords

Article
Publication date: 16 August 2023

Gülşah Ekin Kartal

The aim of this study was to prepare antibacterial capsules and transfer them to cotton fabrics using the impregnation method.

Abstract

Purpose

The aim of this study was to prepare antibacterial capsules and transfer them to cotton fabrics using the impregnation method.

Design/methodology/approach

For this purpose, helichrysum oil was encapsulated by ß-cyclodextrin (ß-CD) using the kneading method at three different molar ratios. The products were then applied to 100% cotton fabric through the impregnation method.

Findings

Morphological assessment showed that the inclusion complex had smooth surfaces and spherical shapes. Fourier transform infrared spectroscopy and differential scanning calorimeter analysis results confirmed the formation of the inclusion complex between ß-CD and the active agent at mole ratios of 1:1, 1:2 and 1:3 for helichrysum oil. According to the analyses, it was determined that the highest complexing rate was between 9.72% and 1:2 in capsules containing ß-CD:helichrysum oil and the sizes of particles which is 1:2 are determined to be between 2 and 25 µm. The presence of capsules on the fabrics was determined after 5 washing cycles. Antibacterial activity was evaluated against Staphylococcus aureus and Escherichia coli bacteria. The antibacterial analysis results showed that the inclusion complex provided a reduction of over 96% against both S. aureus and E. coli bacteria, and the fabrics exhibited antibacterial effects even after 5 washing cycles. The major constituents of the oil were decreased after 5 washes, but significant peaks were remained according to the gas chromatography analyses. These results indicate that helichrysum oil can be used for its antibacterial properties, and it has been observed that this activity continues up to 5 washes when transferred to the fabric in the form of an inclusion complex.

Originality/value

Although helichrysum oil is widely used in cosmetics, there is a lack of studies on its application in textiles. Therefore, this study investigated the potential use of helichrysum oil, which has a wide range of applications, in textiles for its antibacterial properties through molecular encapsulation. The use of naturally sourced substances such as helichrysum oil in the textile industry can offer an environmental and sustainable alternative. This study can be considered as a step toward the development of innovative and naturally sourced antibacterial products in the textile industry.

Details

International Journal of Clothing Science and Technology, vol. 35 no. 5
Type: Research Article
ISSN: 0955-6222

Keywords

Article
Publication date: 12 April 2022

Yousra Trichilli and Mouna Boujelbène Abbes

This article unveils first the lead–lag structure between the confirmed cases of COVID-19 and financial markets, including the stock (DJI), cryptocurrency (Bitcoin) and…

Abstract

Purpose

This article unveils first the lead–lag structure between the confirmed cases of COVID-19 and financial markets, including the stock (DJI), cryptocurrency (Bitcoin) and commodities (crude oil, gold, copper and brent oil) compared to the financial stress index. Second, this paper assesses the role of Bitcoin as a hedge or diversifier by determining the efficient frontier with and without including Bitcoin before and during the COVID-19 pandemic.

Design/methodology/approach

The authors examine the lead–lag relationship between COVID-19 and financial market returns compared to the financial stress index and between all markets returns using the thermal optimal path model. Moreover, the authors estimate the efficient frontier of the portfolio with and without Bitcoin using the Bayesian approach.

Findings

Employing thermal optimal path model, the authors find that COVID-19 confirmed cases are leading returns prices of DJI, Bitcoin and crude oil, gold, copper and brent oil. Moreover, the authors find a strong lead–lag relationship between all financial market returns. By relying on the Bayesian approach, findings show when Bitcoin was included in the portfolio optimization before or during COVID-19 period; the Bayesian efficient frontier shifts to the left giving the investor a better risk return trade-off. Consequently, Bitcoin serves as a safe haven asset for the two sub-periods: pre-COVID-19 period and COVID-19 period.

Practical implications

Based on the above research conclusions, investors can use the number of COVID-19 confirmed cases to predict financial market dynamics. Similarly, the work is helpful for decision-makers who search for portfolio diversification opportunities, especially during health crisis. In addition, the results support the fact that Bitcoin is a safe haven asset that should be combined with commodities and stocks for better performance in portfolio optimization and hedging before and during COVID-19 periods.

Originality/value

This research thus adds value to the existing literature along four directions. First, the novelty of this study lies in the analysis of several financial markets (stock, cryptocurrencies and commodities)’ response to different pandemics and epidemics events, financial crises and natural disasters (Correia et al., 2020; Ma et al., 2020). Second, to the best of the authors' knowledge, this is the first study that examine the lead–lag relationship between COVID-19 and financial markets compared to financial stress index by employing the Thermal Optimal Path method. Third, it is a first endeavor to analyze the lead–lag interplay between the financial markets within a thermal optimal path method that can provide useful insights for the spillover effect studies in all countries and regions around the world. To check the robustness of our findings, the authors have employed financial stress index compared to COVID-19 confirmed cases. Fourth, this study tests whether Bitcoin is a hedge or diversifier given this current pandemic situation using the Bayesian approach.

Details

EuroMed Journal of Business, vol. 18 no. 2
Type: Research Article
ISSN: 1450-2194

Keywords

Article
Publication date: 25 January 2024

Guibin Tan, Jinfu Li, Cheng Zhou, Ziwei Luo, Xing Huang and Fei Guo

This paper aims to focus on the high-speed rotary lip seal in aircraft engines, combining its service parameters, its own structure and application conditions, to study the…

Abstract

Purpose

This paper aims to focus on the high-speed rotary lip seal in aircraft engines, combining its service parameters, its own structure and application conditions, to study the influence of different eccentric forms, eccentricity, rotational speed and other factors on the performance of the rotary lip seal.

Design/methodology/approach

A numerical simulation model for high-speed eccentric rotary lip seals has been developed based on the theory of elastic hydrodynamic lubrication. This model comprehensively considers the coupling of multiple physical fields, including interface hydrodynamics, macroscopic solid mechanics and surface microscopic contact mechanics, under the operating conditions of rotary lip seals. The model takes into account eccentricity and uses the hazardous cross-sectional method to quantitatively predict sealing performance parameters, such as leakage rate and friction force.

Findings

Eccentricity has a large impact on lip seal performance; lips are more susceptible to wear failure under static eccentricity and to leakage failure under dynamic eccentricity.

Originality/value

This study provides a new idea for the design of rotary lip seal considering eccentricity, which is of guiding significance for the engineering application of rotary lip seal.

Details

Industrial Lubrication and Tribology, vol. 76 no. 2
Type: Research Article
ISSN: 0036-8792

Keywords

Executive summary
Publication date: 12 September 2023

INTERNATIONAL: Peak fossil fuels good but tests linger

Details

DOI: 10.1108/OXAN-ES281878

ISSN: 2633-304X

Keywords

Geographic
Topical
Article
Publication date: 4 May 2022

Isiaka Akande Raifu and Sebil Olalekan Oshota

It has been said that oil price shocks affect stock market returns. However, empirical studies remain inconclusive regarding the nexus between oil price shocks and stock market…

Abstract

Purpose

It has been said that oil price shocks affect stock market returns. However, empirical studies remain inconclusive regarding the nexus between oil price shocks and stock market returns. Consequently, the purpose of this study is to investigate the asymmetric impact of oil price shocks on stock returns in Nigeria.

Design/methodology/approach

A two-stage Markov regime-switching approach is used to examine the asymmetric effects of three different structural oil shocks on stock returns. The oil shocks, which include oil supply shock, aggregate demand shock and oil-specific demand shock, are derived using structural vector autoregressive. Monthly data that spans the period between January 1990 and December 2018 are deployed for estimation.

Findings

The linear estimation results show that only oil demand shock negatively and significantly affects the stock market returns. The Markov-switching regime results reveal that oil supply shock has a significant positive impact on the stock returns in a low-volatility state, whereas oil-specific demand shock negatively impacts the stock returns in a high-volatility state.

Practical implications

There is a need for policymakers and investors to take cognizance of not only the positive outcomes of a relatively stable state of oil price but also the negative consequences of a high-volatility state when formulating policy and making investment decisions, respectively.

Originality/value

This study differs from other similar studies in Nigeria that have examined the asymmetric relationship between oil price shocks and stock market return by using a two-stage Markov regime-switching approach. To the best of the authors’ knowledge, this is the first attempt at using this methodology.

Details

International Journal of Energy Sector Management, vol. 17 no. 3
Type: Research Article
ISSN: 1750-6220

Keywords

Article
Publication date: 27 April 2022

Sami A. Ajeel, Mahdi M. Hanoon and Ahmed Mohamed

The low carbon steel used in industrial water conveying pipes in the Dora refinery is corroded. This study aims to reduce corrosion rate in these pipes by using green inhibitor…

Abstract

Purpose

The low carbon steel used in industrial water conveying pipes in the Dora refinery is corroded. This study aims to reduce corrosion rate in these pipes by using green inhibitor extracted from dill plant. This inhibitor is sustainable environmentally.

Design/methodology/approach

The inhibitor extracted from the dill plant was added at different temperatures (25, 40, 60 and 80°C) and at a fixed concentration of 1,400 ppm, as the best protection was obtained at this concentration. The study was carried out under the same conditions using a polarization technique and scanning electron microscope.

Findings

From the results obtained from the polarization curves, it was found that the inhibition efficiency was 92.12% at a concentration of 1,400 ppm and a temperature of 20°C. Potentiodynamic curves showed that both cathodic and anodic reactions were affected by the addition of the inhibitor, indicating that the used inhibitor acted as a mixed type inhibitor, which means that the addition of these inhibitors to the industrial water reduced the anodic dissolution of iron and also retarded the cathodic hydrogen evolution reaction. This reveals that the inhibition mechanism is of the mixed type with a predominant anodic reaction. The results of the fourier transform infrared test indicated that the dill plant contained different chemical bonds (C–H, C = O, S = O, N–O and C–N) that were included in the construction of the barrier layer to protect the steel surface from corrosion.

Originality/value

The dill plant is abundant in nature, its cost is low and its extraction is very easy. It can be used as an environmentally friendly inhibitor to reduce the rate of corrosion in water-carrying pipes used in oil refineries because it contains effective groups (aromatic rings) that combine with metal atoms to form strong bonds that stick to the surface of the metal, which protect it from the attack of the corrosive medium.

Details

World Journal of Engineering, vol. 20 no. 5
Type: Research Article
ISSN: 1708-5284

Keywords

Book part
Publication date: 24 April 2023

Lutz Kilian and Xiaoqing Zhou

Oil market VAR models have become the standard tool for understanding the evolution of the real price of oil and its impact on the macro economy. As this literature has expanded…

Abstract

Oil market VAR models have become the standard tool for understanding the evolution of the real price of oil and its impact on the macro economy. As this literature has expanded at a rapid pace, it has become increasingly difficult for mainstream economists to understand the differences between alternative oil market models, let alone the basis for the sometimes divergent conclusions reached in the literature. The purpose of this survey is to provide a guide to this literature. Our focus is on the econometric foundations of the analysis of oil market models with special attention to the identifying assumptions and methods of inference.

Details

Essays in Honor of Joon Y. Park: Econometric Methodology in Empirical Applications
Type: Book
ISBN: 978-1-83753-212-4

Keywords

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