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Open Access
Article
Publication date: 25 October 2021

Junjie Lu

This study aims to study the gas film stiffness of the spiral groove dry gas seal.

Abstract

Purpose

This study aims to study the gas film stiffness of the spiral groove dry gas seal.

Design/methodology/approach

The present study represents the first attempt to calculate gas film stiffness in consideration of the slipping effect by using the new test technology for dry gas seals. First, a theoretical model of modified generalized Reynolds equation is derived with slipping effect of a micro gap for spiral groove gas seal. Second, the test technology examines micro-scale gas film vibration and stationary ring vibration to determine gas film stiffness by establishing a dynamic test system.

Findings

An optimum value of the spiral angle and groove depth for improved gas film stiffness is clearly seen: the spiral angle is 1.34 rad (76.8º) and the groove depth is 1 × 10–5 m. Moreover, it can be observed that optimal structural parameters can obtain higher gas film stiffness in the experiment. The average error between experiment and theory is less than 20%.

Originality/value

The present study represents the first attempt to calculate gas film stiffness in consideration of the slipping effect by using the new test technology for dry gas seals.

Details

Industrial Lubrication and Tribology, vol. 73 no. 10
Type: Research Article
ISSN: 0036-8792

Keywords

Open Access
Article
Publication date: 30 October 2018

Zbigniew Bieniek, Ida Mascolo and Ada Amendola

This study aims to focus on a short review on recent results dealing with the mechanical modelling and experimental characterization of a novel class of tensegrity structures…

Abstract

Purpose

This study aims to focus on a short review on recent results dealing with the mechanical modelling and experimental characterization of a novel class of tensegrity structures, named class θ = 1 tensegrity prisms. The examined structures exhibit six bars connected by two disjoint sets of strings.

Design/methodology/approach

First, the self-equilibrium problem of tensegrity θ = 1 prisms is numerically investigated for varying values of two aspect parameters and, next, their prestress stability is studied. The mechanical behavior of the examined structures in the large displacements regime under uniform compression loading is also numerically computed through a path-following procedure. Finally, the predicted constitutive response is validated through experimental tests.

Findings

The presented results highlight that the examined structures exhibit a large number of infinitesimal mechanisms from the freestanding configuration, and reveal that they exhibit tunable elastic response switching from stiffening to softening.

Originality/value

This multi-faceted elastic response is in agreement with previous literature results on the elastic response of minimal tensegrity prism, and suggests that such units can be usefully used as non-linear springs in next-generation tensegrity metamaterials.

Details

PSU Research Review, vol. 2 no. 2
Type: Research Article
ISSN: 2399-1747

Keywords

Open Access
Article
Publication date: 23 July 2021

Peter Cincinelli and Domenico Piatti

The paper aims to disentangle the physiological credit risk from the credit risk coming from the inefficient screening and monitoring management process. The analysis is conducted…

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Abstract

Purpose

The paper aims to disentangle the physiological credit risk from the credit risk coming from the inefficient screening and monitoring management process. The analysis is conducted on a sample of 338 Italian banks–56 joint-stock banks (SpA), 23 cooperative banks (Popolari) and 259 mutual banks (BCCs)–over the time period 2006–2017.

Design/methodology/approach

The authors use the maximum likelihood method to estimate the efficient frontier, as a set of best management credit practices, which minimises the credit risk defined on the basis of the level of loans granted, the technical structure of the loan portfolio (such as credit lines, mortgages, consumer loans and other technical loan categories) and the interest rate charges.

Findings

The empirical results show that the increase in non-performing loans (NPLs) is related both to the severe and protracted recession in Italy, which significantly reduced borrowers' capacity to service their debt, and to other factors, such as banks' lending monitoring policies with limited capacity to work-out defaulted loans.

Originality/value

The authors propose a new approach to the study of the performance of the credit process. With the stochastic frontier, the physiological credit risk, assumed by the bank according to its lending activity and management choices, is separated from the credit risk resulting from an inefficient management of the screening and monitoring process. In addition, the authors analyse the determinants of the excess of NPLs. This aspect is considered particularly original because the scientific contributions which consider the causes of NPLs have largely focused on the level of NPLs not considering the physiological part, linked to the structure of the bank's loan portfolio and its operational strategy and therefore not compressible and in any case not attributable to mismanagement or moral hazard.

Details

The Journal of Risk Finance, vol. 22 no. 3/4
Type: Research Article
ISSN: 1526-5943

Keywords

Open Access
Article
Publication date: 10 May 2021

Akinloluwa Samuel Babalola

Values of parameters such as temperature, humidity, number of plastic products and the location of plastic injection moulds are required to determine the efficiency of plastic…

Abstract

Purpose

Values of parameters such as temperature, humidity, number of plastic products and the location of plastic injection moulds are required to determine the efficiency of plastic injection moulds with a view to improving the quality of the outputs. This article determined the appropriate sensors for the measurement of these essential parameters in the most suitable form of representation of the data to aid a proficient analysis of the data.

Design/methodology/approach

The outputs of these sensors were obtained by connecting the sensors to the general-purpose input/output (GPIO) pins of a Raspberry Pi and writing a Python programme for the connected GPIO pins. The values of the outputs of these sensors were represented in a graphical form. The connection of the Raspberry Pi and the sensors were done with a full-sized breadboard and jumper wires. A computer-aided design (CAD) of the connections was produced using Fritzing software.

Findings

The appropriate sensors determined are MLX90614 infrared thermometer sensor, DHT11 humidity sensor, pixy2 vision sensor and Neo-6m GPS sensor. This study proposed that the sensors analytic system be applied on an industrial plastic injection mould to measure and display the various parameters of the injection moulds for the purpose of understanding and improving the performance of the injection mould

Originality/value

An electronic system that provides the continuous values of essential parameters of a plastic injection mould in operation.

Details

Frontiers in Engineering and Built Environment, vol. 1 no. 1
Type: Research Article
ISSN: 2634-2499

Keywords

Open Access
Article
Publication date: 9 November 2021

Achini Tharaka Ranaweera

Touch plays an important role in the evaluations of products. However, prior quantitative touch research does not present a holistic perspective of haptics. This study aims to…

2660

Abstract

Purpose

Touch plays an important role in the evaluations of products. However, prior quantitative touch research does not present a holistic perspective of haptics. This study aims to provide a more comprehensive understanding of haptic information that consumers attain from touch.

Design/methodology/approach

Adopting a qualitative research approach, semi-structured, depth interviews were conducted with industry experts.

Findings

Based on the findings, this research proposes a conceptual model of consumer haptic perception consisting of seven key influences, namely, the effects of haptic sensation, haptic perception, the influence of individual factors, the influence of external environmental factors, the multi-dimensionality of haptics, haptic cue congruity and haptic dominance.

Practical implications

This study suggests firms to understand the importance of consumers’ haptic perception as an opportunity to engage an individual’s heart and mind through information attained through touch.

Originality/value

This is the first study in marketing to propose a conceptual model of haptics comprising several new haptic influences. This model contributes to the emerging literature of sensory marketing by providing directions for future touch research by capturing the dynamic nature of haptics.

Objetivo

El tacto desempeña un papel importante en nuestras evaluaciones de los productos. Sin embargo, las investigaciones cuantitativas anteriores sobre el tacto no presentan una perspectiva holística de la percepción táctil. Este artículo pretende ofrecer una comprensión más completa de la información táctil que los consumidores obtienen del contacto.

Metodología

Adoptando un enfoque de investigación cualitativa, se realizaron entrevistas semiestructuradas en profundidad con expertos del sector.

Resultados

A partir de los resultados, esta investigación propone un modelo conceptual de la percepción táctil del consumidor que consta de siete influencias clave: Los efectos de la sensación háptica, la percepción háptica, la influencia de los factores individuales, la influencia de los factores ambientales externos, la multidimensionalidad de la sensación táctil, la congruencia de las pistas táctiles y la dominancia de la sensación táctil.

Implicaciones prácticas

Este estudio sugiere a las empresas que comprendan la importancia de la percepción táctil de los consumidores como una oportunidad para captar el corazón y la mente del individuo a través de la información obtenida mediante el tacto.

Originalidad

Este es el primer estudio en marketing que propone un modelo conceptual de la percepción táctil que incluye varias influencias táctiles nuevas. Este modelo contribuye a la literatura emergente del marketing sensorial proporcionando direcciones para la futura investigación táctil al capturar la naturaleza dinámica del sentido del tacto.

目的

触摸在我们对产品的评价中起着重要作用。然而, 在先前定量的触觉研究中并未呈现触觉的整体视角。本文旨在更全面地了解消费者通过触摸获得的触觉信息。

方法

本文采用定性研究方法, 与行业专家进行了半结构化的深度访谈。

研究结果

本研究提出了一个消费者触觉感知的概念模型, 其中包括七个关键影响因素:触觉的影响、触觉感知、个人因素的影响、外部环境因素的影响、触觉的多维性、触觉线索的一致性和触觉的主导性。

实际意义

这项研究建议企业了解消费者触觉感知的重要性, 并将触觉信息传达作为吸引消费者心灵的机会。

原创性

这是营销领域首次提出触觉概念模型的研究, 该模型包含几种新的触觉影响因素。这个触觉概念模型通过捕捉触觉的动态特性为未来的触觉研究提供方向, 从而为新兴的感官营销文献做出了贡献。

Open Access
Article
Publication date: 8 November 2023

Armando Di Meglio, Nicola Massarotti, Samuel Rolland and Perumal Nithiarasu

This study aims to analyse the non-linear losses of a porous media (stack) composed by parallel plates and inserted in a resonator tube in oscillatory flows by proposing numerical…

Abstract

Purpose

This study aims to analyse the non-linear losses of a porous media (stack) composed by parallel plates and inserted in a resonator tube in oscillatory flows by proposing numerical correlations between pressure gradient and velocity.

Design/methodology/approach

The numerical correlations origin from computational fluid dynamics simulations, conducted at the microscopic scale, in which three fluid channels representing the porous media are taken into account. More specifically, for a specific frequency and stack porosity, the oscillating pressure input is varied, and the velocity and the pressure-drop are post-processed in the frequency domain (Fast Fourier Transform analysis).

Findings

It emerges that the viscous component of pressure drop follows a quadratic trend with respect to velocity inside the stack, while the inertial component is linear also at high-velocity regimes. Furthermore, the non-linear coefficient b of the correlation ax + bx2 (related to the Forchheimer coefficient) is discovered to be dependent on frequency. The largest value of the b is found at low frequencies as the fluid particle displacement is comparable to the stack length. Furthermore, the lower the porosity the higher the Forchheimer term because the velocity gradients at the stack geometrical discontinuities are more pronounced.

Originality/value

The main novelty of this work is that, for the first time, non-linear losses of a parallel plate stack are investigated from a macroscopic point of view and summarised into a non-linear correlation, similar to the steady-state and well-known Darcy–Forchheimer law. The main difference is that it considers the frequency dependence of both Darcy and Forchheimer terms. The results can be used to enhance the analysis and design of thermoacoustic devices, which use the kind of stacks studied in the present work.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 34 no. 1
Type: Research Article
ISSN: 0961-5539

Keywords

Open Access
Article
Publication date: 4 November 2020

Alberto Moscatello, Anna Chiara Uggenti, Gaetano Iuso, Domenic D'Ambrosio, Gioacchino Cafiero, Raffaella Gerboni and Andrea Carpignano

The purpose of this paper is to present a procedure to design an experimental setup meant to validate an innovative approach for simulating, via computational fluid dynamics, a…

Abstract

Purpose

The purpose of this paper is to present a procedure to design an experimental setup meant to validate an innovative approach for simulating, via computational fluid dynamics, a high-pressure gas release from a rupture (e.g. on an offshore oil and gas platform). The design is based on a series of scaling exercises, some of which are anything but trivial.

Design/methodology/approach

The experimental setup is composed of a wind tunnel, the instrumented scaled (1:10) mock-up of an offshore platform and a gas release system. A correct scaling approach is necessary to define the reference speed in the wind tunnel and the conditions of the gas release to maintain similarity with respect to the real-size phenomena. The scaling of the wind velocity and the scaling of the gas release were inspired by the approach proposed by Hall et al. (1997): a dimensionless group was chosen to link release parameters, wind velocity and geometric scaling factor.

Findings

The theoretical scaling approaches for each different part of the setup were applied to the design of the experiment and some criticalities were identified, such as the existence of a set of case studies with some release parameters laying outside the applicability range of the developed scaling methodology, which will be further discussed.

Originality/value

The resulting procedure is one of a kind because it involves a multi-scaling approach because of the different aspects of the design. Literature supports for the different scaling theories but, to the best of the authors’ knowledge, fails to provide an integrated approach that considers the combined effects of scaling.

Details

Engineering Computations, vol. 38 no. 3
Type: Research Article
ISSN: 0264-4401

Keywords

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