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1 – 10 of over 2000
Article
Publication date: 13 June 2016

Qizi Huang Peng, Tianyu Liu, Quan Sun and Wenwei Huang

As an important connecting component, the reliability of aluminium alloy welded joints influences the whole structural effectiveness and stability of equipment. The…

Abstract

Purpose

As an important connecting component, the reliability of aluminium alloy welded joints influences the whole structural effectiveness and stability of equipment. The purpose of this paper is to propose a novel reliability estimation approach to the welded joints based on time-transformed Wiener process with automatic image measurement of crack growth. The crack length information of the welded joints is incorporated into reliability analysis to reflect the product time-varying characteristics.

Design/methodology/approach

The proposed approach is superior to other crack growth estimations in that it innovatively introduce a non-contact and flexible photogrammetry technique.First, on-line crack growth images of aluminium alloy welded joints are acquired by the designed monitor system. Second, crack length is calculated with image measurement, then the crack growth data during the manufacturing process is prepared. Finally, a time-transformed Wiener process is used to modeling the degradation, and reliability estimation is carried out with Wiener model. The approach has been validated on five 7075-T7351 welded joint samples.

Findings

The method has a twofold task: first, the extraction of crack length growth data by a sequence of image processing. The main step is to model the crack skeleton with crack skeleton tree, and remove it edges to calculate the length of crack; second, the prediction of crack growth and reliability estimation.

Research limitations/implications

The limitation of proposed method should not be ignored. The pixel/mm scale should be calibrated in advance that means once we have built the monitor system, the relative position of the CCD camera and the surveyed crack cannot change anymore. It has reduced the flexibility. To improve this, we can obtain binocular vision in crack image measurement. The 3-D measurements could solve calibration problem and provide more information, such as the depth and the orientation of crack to research. Therefore, future work can be centered on the improvement of monitor system and measurement precision.

Originality/value

In the paper a novel method to estimate reliability of crack growth from welded joint based on image measurement has been presented. This method could be widely applied in different filed of manufacturing systems, reliability engineering and structural analysis.

Details

Engineering Computations, vol. 33 no. 4
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 10 October 2016

Lazhar Tlili, Mehdi Radhoui and Anis Chelbi

The authors consider systems that generate damage to environment as they get older and degrade. The purpose of this paper is to develop an optimal condition-based…

Abstract

Purpose

The authors consider systems that generate damage to environment as they get older and degrade. The purpose of this paper is to develop an optimal condition-based maintenance strategy for such systems in situations where they have a finite operational time requirement. The authors determine simultaneously the optimal number of inspections and the threshold level of environmental damage which minimize the total expected cost over the considered finite time horizon.

Design/methodology/approach

The environmental degradation level is monitored through periodic inspections. The authors model the environmental degradation process due to the equipment’s degradation by the Wiener process. A mathematical model and a numerical procedure are developed. Numerical calculations are performed and the influence of the variation of key parameters on the optimal solution is investigated.

Findings

Numerical tests indicate that as the cost of the penalty related to the generation of an excess damage to environment increases, inspections should become more frequent and the threshold level should be lowered in order to favor preventive actions reducing the probability to pay the penalty.

Research limitations/implications

Given the complexity of the cost function to be minimized, it is difficult to derive analytically the optimal solution. A numerical procedure is designed to obtain the optimal condition-based maintenance policy. Also, the developed model is based on the assumption that the degradation follows a process with stationary independent increments. This may not be appropriate for all types of degradation processes.

Practical implications

The proposed optimal maintenance policy may be relevant and very useful in the perspective of green operations. In fact, this paper offers to decision-makers a comprehensive approach to implement a green maintenance policy and to rapidly understand the net effect of the maintenance policy with respect to environmental regulation requirements.

Originality/value

The main contribution consists in the modeling and optimization of the condition-based maintenance policy over a finite time horizon. Indeed, existing condition-based maintenance models over an infinite time horizon are not applicable for systems with a finite operational time requirement.

Details

Journal of Quality in Maintenance Engineering, vol. 22 no. 4
Type: Research Article
ISSN: 1355-2511

Keywords

Article
Publication date: 13 August 2019

Mohamed El-Beltagy

The paper aims to compare and clarify the differences and between the two well-known decomposition spectral techniques; the Winer–Chaos expansion (WCE) and the…

Abstract

Purpose

The paper aims to compare and clarify the differences and between the two well-known decomposition spectral techniques; the Winer–Chaos expansion (WCE) and the Winer–Hermite expansion (WHE). The details of the two decompositions are outlined. The difficulties arise when using the two techniques are also mentioned along with the convergence orders. The reader can also find a collection of references to understand the two decompositions with their origins. The geometrical Brownian motion is considered as an example for an important process with exact solution for the sake of comparison. The two decompositions are found practical in analysing the SDEs. The WCE is, in general, simpler, while WHE is more efficient as it is the limit of WCE when using infinite number of random variables. The Burgers turbulence is considered as a nonlinear example and WHE is shown to be more efficient in detecting the turbulence. In general, WHE is more efficient especially in case of nonlinear and/or non-Gaussian processes.

Design/methodology/approach

The paper outlined the technical and literature review of the WCE and WHE techniques. Linear and nonlinear processes are compared to outline the comparison along with the convergence of both techniques.

Findings

The paper shows that both decompositions are practical in solving the stochastic differential equations. The WCE is found simpler and WHE is the limit when using infinite number of random variables in WCE. The WHE is more efficient especially in case of nonlinear problems.

Research limitations/implications

Applicable for SDEs with square integrable processes and coefficients satisfying Lipschitz conditions.

Originality/value

This paper fulfils a comparison required by the researchers in the stochastic analysis area. It also introduces a simple efficient technique to model the flow turbulence in the physical domain.

Details

Engineering Computations, vol. 36 no. 7
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 1 December 2003

Hong‐Fwu Yu

At the research and development stage of a product, the manufacturer usually faces the problem of selecting the most reliable design among several competing ones for some…

420

Abstract

At the research and development stage of a product, the manufacturer usually faces the problem of selecting the most reliable design among several competing ones for some parts (or components) of the product in order to enhance the product's quality. It is a great challenge for the manufacturer if these completing designs are highly reliable, since there are few (or even no) failures can be obtained by using traditional life tests or accelerated life tests. In such cases, if there exist product characteristics whose degradation over time can be related to reliability, then collecting “degradation data” can provide information about product reliability. This paper proposes a systematic approach to the selection problem where the products' degradation paths satisfy Wiener processes. First, an intuitively appealing selection rule is proposed and, then, the optimal test plan is derived by using the criterion of minimizing the total experimental cost. The sample size, inspection frequency, and termination time needed by the selection rule for each of competing designs are computed by solving a nonlinear integer programming problem with a minimum probability of correct selection. Finally, an example is provided to illustrate the proposed method.

Details

International Journal of Quality & Reliability Management, vol. 20 no. 9
Type: Research Article
ISSN: 0265-671X

Keywords

Article
Publication date: 11 May 2010

Calum G. Turvey

The purpose of this paper is to review the life of the famous mathematician Kiyosi Itô and discuss his influence on the study of agricultural finance and agricultural economics.

Abstract

Purpose

The purpose of this paper is to review the life of the famous mathematician Kiyosi Itô and discuss his influence on the study of agricultural finance and agricultural economics.

Design/methodology/approach

This paper is a qualitative historical review.

Findings

The paper provides a biographical stretch of Itô's life. It is shown that his influence started to infiltrate the agricultural economics profession at around 1985 and is currently a major influence of a range of economic issues from farm policy to agricultural investments.

Research limitations/implications

The biography is limited to a review of Itô's academic life and influence.

Practical implications

The paper offers a historical perspective on how probability emerged as a critical piece of the economic puzzle. For scholars and practitioners of agricultural finance, the paper provides an in depth review of how Itô processes have, and can, be used.

Originality/value

This paper provides a historical perspective on Itô that is of use to students and scholars of rural credit. This is the first “biography” of Itô to discuss his influence on agricultural finance and agricultural economics.

Details

Agricultural Finance Review, vol. 70 no. 1
Type: Research Article
ISSN: 0002-1466

Keywords

Article
Publication date: 5 March 2021

Mohammad Reza Pourhassan, Sadigh Raissi and Arash Apornak

In some environments, the failure rate of a system depends not only on time but also on the system condition, such as vibrational level, efficiency and the number of…

Abstract

Purpose

In some environments, the failure rate of a system depends not only on time but also on the system condition, such as vibrational level, efficiency and the number of random shocks, each of which causes failure. In this situation, systems can keep working, though they fail gradually. So, the purpose of this paper is modeling multi-state system reliability analysis in capacitor bank under fatal and nonfatal shocks by a simulation approach.

Design/methodology/approach

In some situations, there may be several levels of failure where the system performance diminishes gradually. However, if the level of failure is beyond a certain threshold, the system may stop working. Transition from one faulty stage to the next can lead the system to more rapid degradation. Thus, in failure analysis, the authors need to consider the transition rate from these stages in order to model the failure process.

Findings

This study aims to perform multi-state system reliability analysis in energy storage facilities of SAIPA Corporation. This is performed to extract a predictive model for failure behavior as well as to analyze the effect of shocks on deterioration. The results indicate that the reliability of the system improved by 6%.

Originality/value

The results of this study can provide more confidence for critical system designers who are engaged on the proper system performance beyond economic design.

Details

International Journal of Quality & Reliability Management, vol. 38 no. 10
Type: Research Article
ISSN: 0265-671X

Keywords

Article
Publication date: 1 February 2001

Yuichiro Kawaguchi and Kazuhiro Tsubokawa

This paper proposes a discrete time real options model with time‐dependent and serial correlated return process for a real estate development problem with waiting options…

2110

Abstract

This paper proposes a discrete time real options model with time‐dependent and serial correlated return process for a real estate development problem with waiting options. Based on a Martingale condition, the paper claims to be able to relax many unrealistic assumptions made in the typical real option pricing methodology. Our real option model is a new one without assuming the return process as “Ito Process”, specifically, without assuming a geometric Brownian motion. We apply the model to the condominium market in Tokyo metropolitan area in the period 1971‐1997 and estimate the value of waiting to invest in 1998‐2007. The results partly provide realistic estimates of the parameters and show the applicability of our model.

Details

Journal of Property Investment & Finance, vol. 19 no. 1
Type: Research Article
ISSN: 1463-578X

Keywords

Content available
Book part
Publication date: 20 August 2020

Satya R. Chakravarty and Palash Sarkar

Abstract

Details

An Introduction to Algorithmic Finance, Algorithmic Trading and Blockchain
Type: Book
ISBN: 978-1-78973-894-0

Article
Publication date: 27 November 2017

Kushal Anjaria and Arun Mishra

Situation awareness theory is a primary mean to take decisions and actions in a dynamically changing environment. Nowadays, to implement situation awareness, theories and…

Abstract

Purpose

Situation awareness theory is a primary mean to take decisions and actions in a dynamically changing environment. Nowadays, to implement situation awareness, theories and models in organizational scenarios have become an important research challenge. The purpose of this paper is to investigate the relationship between the situation awareness theory and cybernetics. Further, the aim is to use this relationship to check the feasibility of situation awareness-based information security risk management (ISRM) implementation in the organizational scenario.

Design/methodology/approach

To investigate the relationship between situation awareness theory and cybernetics, Endsley’s situation awareness theory and Norbert Wiener’s cybernetics concepts and philosophy have been used in the present work. For a detailed study, concepts, techniques and philosophy of the cybernetics have been extracted from the thesis of Norbert Wiener titled “The human use of human beings” and “Cybernetics or control and communication in the animal and the machine”.

Findings

The present paper demonstrates that relationship can be successfully established between cybernetics and situation awareness theory. Further, this relationship can be used to solve organizational implementation issues related to situation awareness based systems. To demonstrate relationship and solutions of implementation issues, two case studies related to ISRM are also incorporated in the present case study.

Originality/value

The present work bridges two parallel and prominent theories of situation awareness and cybernetics. It also demonstrates that combination of both the theories can be used to feasibly implement situation awareness based systems in organizations.

Details

Kybernetes, vol. 47 no. 1
Type: Research Article
ISSN: 0368-492X

Keywords

Article
Publication date: 1 August 1994

Felix Geyer and Johannes van der Zouwen

Aims to analyse the influence of Norbert Wiener’s ideas on the social sciences and on social systems, including society as a whole. Describes Wiener’s own attitudes…

326

Abstract

Aims to analyse the influence of Norbert Wiener’s ideas on the social sciences and on social systems, including society as a whole. Describes Wiener’s own attitudes regarding the applicability of cybernetics to social systems and his vision on the development of modern society. Highlights sociologists and political scientists who were inspired by his ideas and deals with researchers who tried to apply his ideas to social systems. Concludes by evaluating to what extent specific ideas of Wiener have impacted on the social sciences.

Details

Kybernetes, vol. 23 no. 6/7
Type: Research Article
ISSN: 0368-492X

Keywords

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