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Article
Publication date: 5 September 2016

Feride Akman and Nevin Çankaya

This paper aims to synthesise and characterise N-cyclohexylmethacrylamide (NCMA) monomer which contains thermosensitive group. The characterisation of monomer was…

Abstract

Purpose

This paper aims to synthesise and characterise N-cyclohexylmethacrylamide (NCMA) monomer which contains thermosensitive group. The characterisation of monomer was performed both theoretically and experimentally.

Design/methodology/approach

The monomer was prepared by reacting cyclohexylamine with methacryloyl chloride in the presence of triethylamine at room temperature. The synthesised monomer was characterised by using not only Density Functional Theory (DFT) and Hartree–Fock (HF) with the Gaussian 09 software but also fourier transform infrared (FT–IR), 1H and 13C nuclear magnetic resonance (NMR) spectroscopy.

Findings

Both the experimental and the theoretical methods demonstrated that the monomer was successfully synthesised. The vibrational frequencies, the molecular structural geometry, such as optimised geometric bond angles, bond lengths and the Mulliken atomic charges of NCMA were investigated by using DFT/B3LYP and HF methods with the 3-21G* basis set. The experimental results were compared with theoretical values. The results revealed that the calculated frequencies were in good accord with the experimental values. Besides, frontier molecular orbitals (FMOs) and molecular electrostatic potential of NCMA were investigated by theoretical calculations at the B3LYP/3–21G* basis set.

Research limitations/implications

Monomer and polymer containing a thermosensitive functional group have attracted great interest from both industrial and academic fields. Their characterisation can provide great opportunities for polymer science by using DFT and HF methods.

Originality/value

The monomer containing a thermosensitive functional group and a various polymer may be prepared by using DFT and HF methods described in this paper. The calculated data are greatly important to provide insight into molecular analysis and then used in technological applications.

Open Access
Article
Publication date: 1 April 2021

Arunit Maity, P. Prakasam and Sarthak Bhargava

Due to the continuous and rapid evolution of telecommunication equipment, the demand for more efficient and noise-robust detection of dual-tone multi-frequency (DTMF…

Abstract

Purpose

Due to the continuous and rapid evolution of telecommunication equipment, the demand for more efficient and noise-robust detection of dual-tone multi-frequency (DTMF) signals is most significant.

Design/methodology/approach

A novel machine learning-based approach to detect DTMF tones affected by noise, frequency and time variations by employing the k-nearest neighbour (KNN) algorithm is proposed. The features required for training the proposed KNN classifier are extracted using Goertzel's algorithm that estimates the absolute discrete Fourier transform (DFT) coefficient values for the fundamental DTMF frequencies with or without considering their second harmonic frequencies. The proposed KNN classifier model is configured in four different manners which differ in being trained with or without augmented data, as well as, with or without the inclusion of second harmonic frequency DFT coefficient values as features.

Findings

It is found that the model which is trained using the augmented data set and additionally includes the absolute DFT values of the second harmonic frequency values for the eight fundamental DTMF frequencies as the features, achieved the best performance with a macro classification F1 score of 0.980835, a five-fold stratified cross-validation accuracy of 98.47% and test data set detection accuracy of 98.1053%.

Originality/value

The generated DTMF signal has been classified and detected using the proposed KNN classifier which utilizes the DFT coefficient along with second harmonic frequencies for better classification. Additionally, the proposed KNN classifier has been compared with existing models to ascertain its superiority and proclaim its state-of-the-art performance.

Details

Applied Computing and Informatics, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 2634-1964

Keywords

Article
Publication date: 10 January 2020

Yining Zeng, Rongxing Duan, Shujuan Huang and Tao Feng

This paper aims to deal with the problems of failure dependence and common cause failure (CCF) that arise in reliability analysis of complex systems.

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Abstract

Purpose

This paper aims to deal with the problems of failure dependence and common cause failure (CCF) that arise in reliability analysis of complex systems.

Design/methodology/approach

Firstly, a dynamic fault tree (DFT) is used to capture the dynamic failure behaviours and converted into an equivalent generalized stochastic petri net (GSPN) for quantitative analysis. Secondly, an efficient decomposition and aggregation (EDA) theory is combined with GSPN to deal with the CCF problem, which exists in redundant systems. Finally, Birnbaum importance measure (BIM) is calculated based on the EDA approach and GSPN model, and it is used to take decisions for system improvement and fault diagnosis.

Findings

In this paper, a new reliability evaluation method for dynamic systems subject to CCF is presented based on the DFT analysis and the GSPN model. The GSPN model is easy to capture dynamic failure behaviours of complex systems, and the movement of tokens in the GSPN model represent the changes in the state of the systems. The proposed method takes advantage of the GSPN model and incorporates the EDA method into the GSPN, which simplifies the reliability analysis process. Meanwhile, simulation results under different conditions show that CCF has made a considerable impact on reliability analysis for complex systems, which indicates that the CCF should not be ignored in reliability analysis.

Originality/value

The proposed method combines the EDA theory with the GSPN model to improve the efficiency of the reliability analysis.

Details

Engineering Computations, vol. 37 no. 5
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 24 May 2013

Tetsushi Yuge, Shinya Ozeki and Shigeru Yanagi

This paper aims to present two methods for calculating the steady state probability of a repairable fault tree with priority AND gates and repeated basic events when the…

Abstract

Purpose

This paper aims to present two methods for calculating the steady state probability of a repairable fault tree with priority AND gates and repeated basic events when the minimal cut sets are given.

Design/methodology/approach

The authors consider a situation that the occurrence of an operational demand and its disappearance occur alternately. We assume that both the occurrence and the restoration of the basic event are statistically independent and exponentially distributed. Here, restoration means the disappearance of the occurring event as a result of a restoration action. First, we obtain the steady state probability of an output event of a single‐priority AND gate by Markov analysis. Then, we propose two methods of obtaining the top event probability based on an Inclusion‐Exclusion method and by considering the sum of disjoint probabilities.

Findings

The closed form expression of steady state probability of a priority AND gate is derived. The proposed methods for obtaining the top event probability are compared numerically with conventional Markov analysis and Monte Carlo simulation to verify the effectiveness. The result shows the effectiveness of the authors’ methods.

Originality/value

The methodology presented shows a new solution for calculating the top event probability of repairable dynamic fault trees.

Details

Journal of Quality in Maintenance Engineering, vol. 19 no. 2
Type: Research Article
ISSN: 1355-2511

Keywords

Book part
Publication date: 11 May 2012

Abigail L. Bristow and Alberto M. Zanni

Purpose – To examine the cost-effectiveness of UK government policy with respect to the mitigation of carbon emissions from the transport sector.Methodology/approach …

Abstract

Purpose – To examine the cost-effectiveness of UK government policy with respect to the mitigation of carbon emissions from the transport sector.

Methodology/approach – Existing policy as set out by the Department for Transport in Low Carbon Transport: A Greener Future is examined. This document elaborates a Low Carbon Transport Strategy intended to achieve annual emissions savings of 17.7 MtCO2 by 2020. A wide range of policy areas where further action could be taken to reduce carbon emissions are examined and their cost-effectiveness considered.

Findings – Measures that influence behaviour including smarter choices, eco-driving across modes, freight best practice and modest price increases are highly cost-effective. More cost-effective routes to saving 17.7 MtCO2 are identified, as are further cost-effective savings.

Originality/value – It appears that government targets could be delivered and indeed exceeded at lower cost than the Low Carbon Transport Strategy. However, policy development is influenced by a wide range of factors which help to explain why cost-effective measures are not always fully exploited.

Details

Transport and Climate Change
Type: Book
ISBN: 978-1-78052-440-5

Keywords

Article
Publication date: 22 May 2020

Aryana Collins Jackson and Seán Lacey

The discrete Fourier transformation (DFT) has been proven to be a successful method for determining whether a discrete time series is seasonal and, if so, for detecting…

Abstract

Purpose

The discrete Fourier transformation (DFT) has been proven to be a successful method for determining whether a discrete time series is seasonal and, if so, for detecting the period. This paper deals exclusively with rare data, in which instances occur periodically at a low frequency.

Design/methodology/approach

Data based on real-world situations is simulated for analysis.

Findings

Cycle number detection is done with spectral analysis, period detection is completed using DFT coefficients and signal shifts in the time domain are found using the convolution theorem. Additionally, a new method for detecting anomalies in binary, rare data is presented: the sum of distances. Using this method, expected events which have not occurred and unexpected events which have occurred at various sampling frequencies can be detected. Anomalies which are not considered outliers to be found.

Research limitations/implications

Aliasing can contribute to extra frequencies which point to extra periods in the time domain. This can be reduced or removed with techniques such as windowing. In future work, this will be explored.

Practical implications

Applications include determining seasonality and thus investigating the underlying causes of hard drive failure, power outages and other undesired events. This work will also lend itself well to finding patterns among missing desired events, such as a scheduled hard drive backup or an employee's regular login to a server.

Originality/value

This paper has shown how seasonality and anomalies are successfully detected in seasonal, discrete, rare and binary data. Previously, the DFT has only been used for non-rare data.

Details

Data Technologies and Applications, vol. 54 no. 2
Type: Research Article
ISSN: 2514-9288

Keywords

Article
Publication date: 9 July 2020

Gong Chen, Shaojie Liu, Zhigong Tang, Jiangtao Xu and Wenzheng Wang

The modern missile has low uncertain and wide range vibration frequency. The conventional notch filter with the fixed notch frequency is less effective than that of the…

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Abstract

Purpose

The modern missile has low uncertain and wide range vibration frequency. The conventional notch filter with the fixed notch frequency is less effective than that of the adaptive notch filter (ANF) in vibration suppression for the time-varying vibration frequency.

Design/methodology/approach

To overcome the drawback, a novel method is based on frequency estimators made by interpolation of three discrete Fourier transform (DFT) spectral lines. The modified frequency estimators based on the interpolation of three DFT spectral lines are presented to identify and track the vibration frequency. Then the notch frequencies of multiple ANFs are real-timely tuned according to estimators.

Findings

Finally, taking the second-order flexible missile as an example, the performance of the proposed method is verified. The verified simulation results show that multiple ANFs are effective in vibration suppression.

Practical implications

Cascading multiple ANFs to achieve multi-order vibration suppression is more efficient and feasible than conventional fixed-parameter notch filtering.

Originality/value

The frequency estimation method based on three DFT spectral lines proposed in this paper can effectively identify and track signals in the noise environment. Compared with conventional methods, the method pretended in this paper has high identification accuracy and a stronger ability to track signals. It can meet the fast frequency identification requirements of the actual flexible missile.

Details

Aircraft Engineering and Aerospace Technology, vol. 92 no. 8
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 26 September 2022

Brinda Sampat, Sahil Raj, Abhishek Behl and Sofia Schöbel

This paper examines the influence of facilitators and barriers on employees’ preference to work in a hybrid model. The study uses the theoretical lens of…

Abstract

Purpose

This paper examines the influence of facilitators and barriers on employees’ preference to work in a hybrid model. The study uses the theoretical lens of stimulus-organism-response (SOR) and dual factor theory (DFT). It examines the influence of health consciousness (stimulus), facilitators (e.g. work flexibility, work–life balance and team building) (organism) and barriers (e.g. pandemic and travel stressor and role overload [organism] on employees’ preference to work in a hybrid model) (response). Further, it tests the moderating influence of organizational culture.

Design/methodology/approach

A questionnaire survey was conducted among employees in India, Sri Lanka and Germany, obtaining 281 usable questionnaires. Structural equation modeling (SEM) using Warp PLS 7.0 was used as the analytical technique to examine the model fit and test hypotheses.

Findings

The findings reveal that health consciousness is essential in enhancing facilitators and motivating employees to prefer a hybrid working model. The study’s findings also prove the positive influence of work flexibility, work–life balance and team building as facilitators. The results suggest that pandemic and travel stressors inhibit employees’ preference for working in a hybrid model.

Research limitations/implications

The study is based on a cross-sectional research design to generalise the findings. Future researchers can utilize longitudinal design to decipher the variation in response over time. The study has developed a model combining SOR with DFT; the authors suggest that future researchers use other theories in combination with SOR, like self-determination theory (SDT), to decipher the influence of intrinsic and extrinsic motivation of employees in the context of the hybrid working model.

Practical implications

This study identifies the need for open communication with the employees to overcome their concerns regarding the hybrid working model. The study also suggests that human resource (HR) managers need to prioritize the task that needs to be accomplished from the office versus working from home. The authors recommend various measures, like water cooler breaks and a buddy system, to motivate employees to work in a hybrid model.

Originality/value

This study is among the first studies focused on the hybrid working model. The current study adds to the limited literature on the facilitators and barriers of working in a hybrid work model.

Details

Personnel Review, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0048-3486

Keywords

Book part
Publication date: 1 December 2017

Kit Mitchell

Changes in physiology associated with ageing mean increased concern for the safety of older drivers and the risk they may pose on other road users. The risk of older…

Abstract

Changes in physiology associated with ageing mean increased concern for the safety of older drivers and the risk they may pose on other road users. The risk of older drivers is distorted by their fragility; they are more likely to be injured or die in road collisions compared to a younger person. Older drivers are, overall, safe drivers who pose similar risks to other road users as middle-aged drivers, but who are at risk themselves because of their fragility. The fragility is greater in older females than older men; females over the age of 80 are nine times more likely to die from their injuries compared to 40–49-year old females, while men are at least five times more likely. Older drivers are overrepresented in collisions at junctions that have no formal traffic control and underrepresented in crashes that involve excess speed. While it is not possible to put traffic signals in every junction, it is suggested consideration be given to mini roundabouts or three-way stop-sign junctions (as found in United States and South Africa). There is no evidence that stringent testing for licence renewal has advantages in reducing older driver risk. Assessments at specialist centres, such as mobility assessment centres, are a more effective way to pick up drivers who are no longer safe to drive.

Details

Transport, Travel and Later Life
Type: Book
ISBN: 978-1-78714-624-2

Keywords

Book part
Publication date: 8 August 2022

Jools Townsend

Community rail is a grassroots movement that spans Britain, made up of hundreds of community groups and partnerships that engage people with their railways and stations

Abstract

Community rail is a grassroots movement that spans Britain, made up of hundreds of community groups and partnerships that engage people with their railways and stations and provide a bridge between the rail industry and the public at a local level. The movement has grown up from the grassroots, but it has also been increasingly supported and nurtured by the rail industry, with train operators proactively encouraging its spread and development. They, and national and devolved governments, recognise the value of community rail, and its contribution to social inclusion, sustainable development and the railway’s ability to prosper and serve passengers and communities well, now and in the future. This idea is supported by passenger data showing that railway lines with community rail partnerships – working to enhance, promote and aid access to those lines – outperform comparable lines. A swathe of qualitative evidence shows community rail partnerships and station groups having a demonstrable impact on their localities and people’s lives, and appreciation of this role by industry leaders. The many examples of community rail volunteers and practitioners bringing about positive change resonate with academic research exploring how civic engagement and local efficacy and communications can support change, particularly with regard to sustainable behaviours and development. A range of researchers argue that localised, interactive engagement and communications may be the key, when it comes to bringing about the major shifts in behaviour needed to address the global, existential threat posed by the climate crisis, which unsustainable behaviours and policies have brought about. In this way, evidence suggests that engaging communities with their railways, and local transport networks generally, is critical, both to these networks operating in a truly sustainable manner and to achieving inter- and intra-generational equity within the communities they serve.

Details

Sustainable Railway Engineering and Operations
Type: Book
ISBN: 978-1-83909-589-4

Keywords

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