CERES :: Browsing by Author "Mehnen, Jorn"

Browsing by Author "Mehnen, Jorn"

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Open Access
Business process mining for industry: successes and caveats
(2010-06-23T00:00:00Z) Mehnen, Jorn; Turner, Christopher J.; Tiwari, Ashutosh; R. Teti
Business Process Mining (BPM) is a powerful technique which aims at mapping the complex structure of industrial processes into human interpretable graph structures by analysing business process traces automatically. The transfer of an innovative idea into an industrially viable product is a challenging task in its own rights. First, this paper introduces the concept of business process mining and an innovative Genetic Programming (GP) approach. Second, this paper addresses the principal caveats and solutions that come with transferring new academic solutions into real-world applications. A real BPM transfer project serves a background for this discussion.
Open Access
Challenges of cloud technology in manufacturing environment
(Cranfield University Press, 2013-09-19) Yadekar, Yaser; Shehab, Essam; Mehnen, Jorn
The rapid growth Information systems and advanced network technologies have significant impact on enterprises around the world. Enterprises are trying to gain competitive advantage in open global markets by using the latest technologies, along with advanced networks, to create collaboration, reduce costs, and maximize productivity. The combination of latest technologies and advanced manufacturing networks technologies lead to growth of new manufacturing model named Cloud Manufacturing which can shift the manufacturing industry from product-oriented manufacturing to services-oriented manufacturing. This paper explores the literature about the current Manufacturing problems, understands the concept of Cloud Computing Technology, introduces Cloud Manufacturing and its role in the enterprise, and investigates the obstacles and challenges of adopting Cloud Manufacturing in enterprises.
Open Access
Characterisation of integrated WAAM and machining processes
(Cranfield University, 2013-12) Adebayo, Adeyinka; Mehnen, Jorn; Tonnellier, Xavier P.
This research describes the process of manufacturing and machining of wire and arc additive manufactured (WAAM) thin wall structures on integrated and non¬integrated WAAM systems. The overall aim of this thesis is to obtain a better understanding of deposition and machining of WAAM wall parts through an integrated system. This research includes the study of the comparison of deposition of WAAM wall structures on different WAAM platforms, namely an Integrated SAM Edgetek grinding machine, an ABB robot and a Friction Stir Welding (FSW) machine. The result shows that WAAM is a robustly transferable technique that can be implemented across a variety of different platforms typically available in industry. For WAAM deposition, a rise in output repeatedly involves high welding travel speed that usually leads to an undesired humping effect. As part of the objectives of this thesis was to study the travel speed limit for humping. The findings from this research show that the travel speed limit falls within a certain region at which humping starts to occur. One of the objectives of this thesis was to study the effect of lubricants during sequential and non-sequential machining/deposition of the WAAM parts. Conventional fluid lubricants and solid lubricants were used. In addition, the effect of cleaning of deposited wall samples with acetone was also studied. A systematic study shows that a significant amount of solid lubricant contamination can be found in the deposited material. Furthermore, the results indicate that even cleaning of the wire and arc additive manufactured surfaces with acetone prior to the weld deposition can affect the microstructure of the deposited material.
Open Access
A CNC machine guiderail wear in-process monitoring system
(Cranfield University, 2016-09) Zhao, Yifei; Mehnen, Jorn; Salonitis, Konstantinos
This research investigates and establishes a system for monitoring the guiderail wear on medium size CNC machines. The system possesses the function of measuring the wear state on guiderails in an in-process way, which is more functional and efficient than the traditional method. In this research, two different types of sensors for monitoring each particular friction wear feature have been implemented. Calculations to complete designing of a physical experimental rig and the realisation of in-process monitoring are also discussed in detail. The first type sensor adopted in the experiment is the accelerometer, used for monitoring the vibration caused by the wear on bearings and the increasing roughness on the guiderail surface. The second sensor is the capacitance probe mounted on the table and against a straight edge, searching the deviation signal of the moving table while rolling on the guiderail surface with wear. The novelty of this thesis covering an in-process monitoring approach has been tested based on a physical experimental rig. The data calculation illustrates how the noise and other disturbances are filtered and data analysed to determine the state of wear. This system utilises an indirect solution to wear monitoring with less cost while delivering convincing reliability according to the experiment result. The thesis shows the possibility to acquire CNC machine guiderail wear data through an in-process monitoring system.
Open Access
A coefficient clustering analysis for damage assessment of composites based on pulsed thermographic inspection
(Elsevier, 2016-06-11) Zhao, Yifan; Tinsley, Lawrence; Addepalli, Sri; Mehnen, Jorn; Roy, Rajkumar
This paper introduces a coefficient clustering analysis method to detect and quantitatively measure damage occurring in composite materials using pulsed thermographic inspection. This method is based on fitting a low order polynomial model for temperature decay curves, which (a) provides an enhanced visual confirmation and size measurement of the damage, (b) provides the reference point for sound material for further damage depth measurement, (c) and reduces the burden in computational time. The performance of the proposed method is evaluated through a practical case study with carbon fibre reinforced polymer (CFRP) laminates which were subjected to a drop impact test with varying energy levels. A novel method for reducing an entire thermogram sequence into a single image is introduced, which provides an enhanced visualisation of the damage area.
Open Access
A comparison of resource allocation process in grid and cloud technologies
(IOP, 2018-06-04) Hallawi, Huda; Mehnen, Jorn; He, Hongmei
Grid Computing and Cloud Computing are two different technologies that have emerged to validate the long-held dream of computing as utilities which led to an important revolution in IT industry. These technologies came with several challenges in terms of middleware, programming model, resources management and business models. These challenges are seriously considered by Distributed System research. Resources allocation is a key challenge in both technologies as it causes the possible resource wastage and service degradation. This paper is addressing a comprehensive study of the resources allocation processes in both technologies. It provides the researchers with an in-depth understanding of all resources allocation related aspects and associative challenges, including: load balancing, performance, energy consumption, scheduling algorithms, resources consolidation and migration. The comparison also contributes an informal definition of the Cloud resource allocation process. Resources in the Cloud are being shared by all users in a time and space sharing manner, in contrast to dedicated resources that governed by a queuing system in Grid resource management. Cloud Resource allocation suffers from extra challenges abbreviated by achieving good load balancing and making right consolidation decision.
Open Access
Data mining and knowledge reuse for the initial systems design and manufacturing: Aero-engine service risk drivers
(Elsevier, 2013-09-27) Morar, Nicolau; Rajkumar, Roy; Mehnen, Jorn; Redding, Louis E.; Harrison, Andrew
Service providers of civil aero engines are typically confronted with a high cost of maintenance, replacement and refurbishment of the service damaged components. In such context, service experience becomes a key issue for determining the service risk drivers for operational disruptions and maintenance burden. This paper presents an industrial case study to produce new knowledge on the relationships between degradation and component design to manufacture. The study applied semantic data mining as a methodology for an efficient and the consistent data capture, representation, and analysis. The paper aims at identifying the service risk drivers based on service experience and event data. The analysis shows that the 3 top mechanisms accounting for 32% of the mechanism references have a strong Pareto effect. The paper concludes with missing information links and future research directions.
Open Access
Degradation assessment of industrial composites using thermography
(Elsevier, 2015-10) Zhao, Yifan; Mehnen, Jorn; Xu, Wei; Alrashed, Mosab; Abineri, Stephen; Roy, Rajkumar
Thermographic inspection is a relatively new technique for Non-Destructive Testing (NDT) which has been gathering increasing interest due to its relatively low cost hardware and extremely fast data acquisition properties. This technique is especially promising in the area of rapid automated damage detection and quantification. In collaboration with a major industry partner from the aerospace sector advanced thermography-based NDT software for impact damaged composites is introduced. The software is based on correlation analysis of time-temperature profiles in combination with an image enhancement process. The prototype software is aiming to a) better visualise the damages in a relatively easy-to-use way and b) automatically and quantitatively measure the properties of the degradation. Knowing that degradation properties play an important role in the identification of degradation types, tests and results on specimens which were artificially damaged have been performed and analyzed.
Open Access
A design approach to IoT endpoint security for production machinery monitoring
(MDPI, 2019-05-16) Tedeschi, Stefano; Emmanouilidis, Christos; Mehnen, Jorn; Roy, Rajkumar
The Internet of Things (IoT) has significant potential in upgrading legacy production machinery with monitoring capabilities to unlock new capabilities and bring economic benefits. However, the introduction of IoT at the shop floor layer exposes it to additional security risks with potentially significant adverse operational impact. This article addresses such fundamental new risks at their root by introducing a novel endpoint security-by-design approach. The approach is implemented on a widely applicable production-machinery-monitoring application by introducing real-time adaptation features for IoT device security through subsystem isolation and a dedicated lightweight authentication protocol. This paper establishes a novel viewpoint for the understanding of IoT endpoint security risks and relevant mitigation strategies and opens a new space of risk-averse designs that enable IoT benefits, while shielding operational integrity in industrial environments.
Open Access
Design for wire and arc additive layer manufacture
(2010-04-19T00:00:00Z) Mehnen, Jorn; Ding, J.; Lockett, Helen L.; Kazanas, P.; Bernard, A.
Additive Layer Manufacture (ALM) is a technique whereby freeform structures are produced by building up material in layers. RUAM (Ready-to-Use Additive Layer Manufacturing) is an innovative concept for building large scale metal ready-to- use parts. The design for RUAM has several process steps: the geometric design of the parts taking the complex process behaviour of the arc welding process into account; FEM to predict temperature and stress distributions to minimise part distortions; and efficient robot tool path design. This paper covers these essential design steps from a technical as well as practical point of view.
Open Access
Determination of thermal wave reflection coefficient to better estimate defect depth using pulsed thermography
(Elsevier, 2017-08-22) Sirikham, Adisorn; Zhao, Yifan; Mehnen, Jorn
Thermography is a promising method for detecting subsurface defects, but accurate measurement of defect depth is still a big challenge because thermographic signals are typically corrupted by imaging noise and affected by 3D heat conduction. Existing methods based on numerical models are susceptible to signal noise and methods based on analytical models require rigorous assumptions that usually cannot be satisfied in practical applications. This paper presents a new method to improve the measurement accuracy of subsurface defect depth through determining the thermal wave reflection coefficient directly from observed data that is usually assumed to be pre-known. This target is achieved through introducing a new heat transfer model that includes multiple physical parameters to better describe the observed thermal behaviour in pulsed thermographic inspection. Numerical simulations are used to evaluate the performance of the proposed method against four selected state-of-the-art methods. Results show that the accuracy of depth measurement has been improved up to 10% when noise level is high and thermal wave reflection coefficients is low. The feasibility of the proposed method in real data is also validated through a case study on characterising flat-bottom holes in carbon fibre reinforced polymer (CFRP) laminates which has a wide application in various sectors of industry.
Open Access
Development of an ontology for aerospace engine components degradation in service
(ScitePress, 2014-12-31) Okoh, Caxton; Roy, Rajkumar; Mehnen, Jorn; Redding, Louis E.; Harrison, Alan
This paper presents the development of an ontology for component service degradation. In this paper, degradation mechanisms in gas turbine metallic components are used for a case study to explain how a taxonomy within an ontology can be validated. The validation method used in this paper uses an iterative process and sanity checks. Data extracted from on-demand textual information are filtered and grouped into classes of degradation mechanisms. Various concepts are systematically and hierarchically arranged for use in the service maintenance ontology. The allocation of the mechanisms to the AS-IS ontology presents a robust data collection hub. Data integrity is guaranteed when the TO-BE ontology is introduced to analyse processes relative to various failure events. The initial evaluation reveals improvement in the performance of the TO-BE domain ontology based on iterations and updates with recognised mechanisms. The information extracted and collected is required to improve service k nowledge and performance feedback which are important for service engineers. Existing research areas such as natural language processing, knowledge management, and information extraction were also examined.
Open Access
The effect of trepanning speed of laser drilled acute angled cooling holes on the high temperature low cycle corrosion fatigue performance of CMSX-4 at 850 °C
(Elsevier, 2017-05-04) Morar, Nicolau; Roy, Rajkumar; Mehnen, Jorn; Nicholls, John R.; Gray, Simon
The effect of laser trepanning speed and, as a result, recast layer thickness on the high temperature corrosion fatigue behaviour of CMSX-4 superalloy acute angled holes was investigated. The experimental test results show that an increasing laser drilling speed caused a reduction in corrosion fatigue life by 35–50% at 850 °C, under low cycle fatigue regime. This reduction was found to correlate directly with the recast layer thickness and surface anomalies within the recast layer produced during the laser drilling process. Corrosion had a smaller effect on the overall life of the laser drilled specimens under the conditions tested. The results presented show that laser trepanning speed is influential in limiting the life performance of laser drilled components in service.
Open Access
The effect of trepanning speed of laser drilled acute angled cooling holes on the high temperature low cycle corrosion fatigue performance of CMSX-4 at 850°C
(Elsevier, 2017-05-04) Morar, N.; Roy, Rajkumar; Mehnen, Jorn; Nicholls, John R.; Gray, Simon
The effect of laser trepanning speed and, as a result, recast layer thickness on the high temperature corrosion fatigue behaviour of CMSX-4 superalloy acute angled holes was investigated. The experimental test results show that an increasing laser drilling speed caused a reduction in corrosion fatigue life by 30-50% at 850°C, under low cycle fatigue regime. This reduction was found to correlate directly with the recast layer thickness and surface anomalies within the recast layer produced during the laser drilling process. Corrosion had a smaller effect on the overall life of the laser drilled specimens under the conditions tested. The results presented show that laser trepanning speedis influencial in limiting the life performance of laser drilled components in service.
Open Access
Effects of solid lubricants on wire and arc additive manufactured structures
(Professional Engineering Publishing, 2014-04-01T00:00:00Z) Adebayo, Yinka; Mehnen, Jorn; Tonnellier, Xavier
This paper reports a systematic study which examines the use of solid lubricants in the sequential deposition and machining of wire and arc additive manufactured parts and characterises the effects of solid lubricants on the microstrucure. This paper also describes the microstructure developed and the effect on micro hardness by manual cleaning of deposited layers with acetone. Mild steel wire consumable electrode G3Si1 with the diameter of 0.8mm was used. The use of graphite and molybdenum disulphide as solid lubricant in machining was also studied and a scanning electron microscope was used in detecting any form of lubricants contamination. A systematic study shows that a significant amount of solid lubricant contamination can be found in the deposited material. Furthermore, the results indicate that even cleaning of the wire and arc additive manufactured surfaces with acetone prior to the weld deposition can affect the microstructure of the deposited material.
Open Access
Enterprise resource planning system implementation and success measurement : case study of a small to medium sized enterprise
(Cranfield University, 2014-03) Shaikh, N.; Williams, Leon; Mehnen, Jorn
It is widely believed that major financial benefits can be achieved by organisations implementing Enterprise Resource Planning software. It is also believed that such systems are a time consuming and a costly endeavour which can result in loss of resource and eventually failure of implementation. Furthermore not all companies have the technical competence or financial stability to take such a risk. Alternatively companies can be more modular in their approach in implementing such solutions, adopting one module at a time: the one that suits them best according to their financial and technical situation and so gradually work towards Enterprise Resource Planning implementation. A measurement technique is also required to track progress, success and failure of such a process. As global trade routes become more affordable and the cost of shipping becomes marginalised compared to the overall cost of a product there is a direct impact on Small to Medium sized enterprises as they start competing with global businesses and not just locally. Enterprise Resource Planning or ERP's are one of the many tools that a company can utilise to enhance its efficiency and become more competitive however implementing such a technology is an expensive and risky undertaking. This thesis aims to outline the systems and technologies that a SME can utilise to achieve such a goal using open-source software infrastructure while reducing the expenses and risk involved. It also points out a more “one step at a time” approach to such implementations, hinting that you implement only what you can afford in terms of time and resource and then build towards a bigger system when time and cash prevails hence having a gradual improvement to the overall ecosystem. The observations derived in this paper are outputs of implementation of such technologies at a local SME acting as the case study. Results show that although such an approach can be helpful in bringing the development cost down, continuous efforts in improving the system and on-going systems support is required for the post-implementation phase to have a positive impact on the performance of the company.
Open Access
Feature based cost and carbon emission modelling for wire and arc additive manufacturing
(Cranfield University, 2012-12) Guo, Jianing; Mehnen, Jorn; Xu, Yuchun
The wire and arc additive manufacturing (WAAM) is a CNC and welding deposition based additive manufacturing method. This novel manufacturing technique has potential cost and environment advantage and was developed as an ideal alternative for industrial sustainable development. The aim of this project is to develop a cost and carbon emission model primarily for the WAAM manufacturing cost (£) calculation and secondly for the WAAM carbon emission (KgCO2e) estimation, which can be used by the decision makers and design engineers in product design stage without detailed process information. Literature review and an industry survey were carried out first to capture the overview of this research context and the essential data for cost modelling. Then the cost breakdown structure (CBS) and cost drivers were determined. Thereafter, a feature based cost model and detailed cost equations were developed. A specific Greenhouse Gases (GHG) emission model was also established which follows the specification of existing carbon footprint measurement standards. As part of this project, an integrated software tool was developed by using MS Visual Basic language. The proposed cost and GHG emission model were implemented in this software. With the ability of directly capture geometry data from CAD files and fully automatic calculation, the software tool is efficient and convenient. Three case studies were conducted to demonstrate the proposed cost model and software tool. The comparative cost analyses with other conventional manufacturing methods were also discussed in these case studies. Finally, the capacity and reliability of the cost software were validated by experts from industry and academia. The implementation of the research outcomes of this project can achieve accurate early cost estimation for WAAM conveniently. Moreover, it can clarify the cost and environment advantage of WAAM and assist to identify the most suitable situation for adopting WAAM from a cost and sustainable point of view.
Open Access
A framework development to predict remaining useful life of a gas turbine mechanical component
(2017-09) Okoh, Caxton; Roy, Rajkumar; Mehnen, Jorn
Power-by-the-hour is a performance based offering for delivering outstanding service to operators of civil aviation aircraft. Operators need to guarantee to minimise downtime, reduce service cost and ensure value for money which requires an innovative advanced technology for predictive maintenance. Predictability, availability and reliability of the engine offers better service for operators, and the need to estimate the expected component failure prior to failure occurrence requires a proactive approach to predict the remaining useful life of components within an assembly. This research offers a framework for component remaining useful life prediction using assembly level data. The thesis presents a critical analysis on literature identifying the Weibull method, statistical technique and data-driven methodology relating to remaining useful life prediction, which are used in this research. The AS-IS practice captures relevant information based on the investigation conducted in the aerospace industry. The analysis of maintenance cycles relates to the examination of high-level events for engine availability, whereby more communications with industry showcase a through-life performance timeline visualisation. Overhaul sequence and activities are presented to gain insights of the timeline visualisation. The thesis covers the framework development and application to gas turbine single stage assembly, repair and replacement of components in single stage assembly, and multiple stage assembly. The framework is demonstrated in aerospace engines and power generation engines. The framework developed enables and supports domain experts to quickly respond to, and prepare for maintenance and on-time delivery of spare parts. The results of the framework show the probability of failure based on a pair of error values using the corresponding Scale and Shape parameters. The probability of failure is transformed into the remaining useful life depicting a typical Weibull distribution. The resulting Weibull curves developed with three scenarios of the case shows there are components renewals, therefore, the remaining useful life of the components are established. The framework is validated and verified through a case study with three scenarios and also through expert judgement.
Open Access
A framework to manage uncertainties in cloud manufacturing environment
(Cranfield University, 2016-10) Yadekar, Yaser; Shehab, Essam; Mehnen, Jorn
This research project aims to develop a framework to manage uncertainty in cloud manufacturing for small and medium enterprises (SMEs). The framework includes a cloud manufacturing taxonomy; guidance to deal with uncertainty in cloud manufacturing, by providing a process to identify uncertainties; a detailed step-by-step approach to managing the uncertainties; a list of uncertainties; and response strategies to security and privacy uncertainties in cloud manufacturing. Additionally, an online assessment tool has been developed to implement the uncertainty management framework into a real life context. To fulfil the aim and objectives of the research, a comprehensive literature review was performed in order to understand the research aspects. Next, an uncertainty management technique was applied to identify, assess, and control uncertainties in cloud manufacturing. Two well-known approaches were used in the evaluation of the uncertainties in this research: Simple Multi-Attribute Rating Technique (SMART) to prioritise uncertainties; and a fuzzy rule-based system to quantify security and privacy uncertainties. Finally, the framework was embedded into an online assessment tool and validated through expert opinion and case studies. Results from this research are useful for both academia and industry in understanding aspects of cloud manufacturing. The main contribution is a framework that offers new insights for decisions makers on how to deal with uncertainty at adoption and implementation stages of cloud manufacturing. The research also introduced a novel cloud manufacturing taxonomy, a list of uncertainty factors, an assessment process to prioritise uncertainties and quantify security and privacy related uncertainties, and a knowledge base for providing recommendations and solutions.
Open Access
A framework to manage uncertainties in cloud manufacturing environment
(Cranfield University, 2016-10) Yadekar, Yaser; Shehab, Essam; Mehnen, Jorn
This research project aims to develop a framework to manage uncertainty in cloud manufacturing for small and medium enterprises (SMEs). The framework includes a cloud manufacturing taxonomy; guidance to deal with uncertainty in cloud manufacturing, by providing a process to identify uncertainties; a detailed step-by-step approach to managing the uncertainties; a list of uncertainties; and response strategies to security and privacy uncertainties in cloud manufacturing. Additionally, an online assessment tool has been developed to implement the uncertainty management framework into a real life context. To fulfil the aim and objectives of the research, a comprehensive literature review was performed in order to understand the research aspects. Next, an uncertainty management technique was applied to identify, assess, and control uncertainties in cloud manufacturing. Two well-known approaches were used in the evaluation of the uncertainties in this research: Simple Multi-Attribute Rating Technique (SMART) to prioritise uncertainties; and a fuzzy rule-based system to quantify security and privacy uncertainties. Finally, the framework was embedded into an online assessment tool and validated through expert opinion and case studies. Results from this research are useful for both academia and industry in understanding aspects of cloud manufacturing. The main contribution is a framework that offers new insights for decisions makers on how to deal with uncertainty at adoption and implementation stages of cloud manufacturing. The research also introduced a novel cloud manufacturing taxonomy, a list of uncertainty factors, an assessment process to prioritise uncertainties and quantify security and privacy related uncertainties, and a knowledge base for providing recommendations and solutions.