• An advanced FEA based force induced error compensation strategy in milling

      Ratchev, Svetan; Liu, Shulong; Huang, Wei; Becker, Adib A.; University of Nottingham (Elsevier, 2006-04)
      The study introduces a multi-level machining error compensation approach focused on force-induced errors in machining of thin-wall structures. The prediction algorithm takes into account the deflection of the part in different points of the tool path. The machining conditions are modified at each step when the cutting force and deflection achieve a local equilibrium. The machining errors are predicted using a theoretical flexible force-deflection model. The error compensation is based on optimising the tool path taking into account the predicted milling error. The error compensation scheme is simulated using NC simulation package and is experimentally verified.
    • An advanced machining simulation environment employing workpiece structural analysis

      Ratchev, Svetan; Liu, Shulong; Huang, Wei; Becker, Adib A.; University of Nottingham (World Academy of Materials and Manufacturing Engineering, 2006)
      Purpose: The study aims to reduce the surface dimensional error due to the part deflection during the machining of thin wall structures, thus, reduce machining costs and lead times by producing “right first time” components.Design/methodology/approach: The proposed simulation environment involves a data model, an analytical force prediction model, a material removal model and an FE analysis commercial software package. It focuses on the development of the simulation environment with a multi-level machining error compensation approach.Findings: The developed simulation environment can predict and reduce the form error, which is a limitation of the existing approaches.Research limitations/implications: The energy consumption, temperature change and residual stress are not studied in this research.Practical implications: The developed method provides a platform to deliver new functionality for machining process simulation. The convergence of the proposed integrated system can be achieved quickly after only a few iterations, which makes the methodology reliable and efficient.Originality/value: The study offers an opportunity to satisfy tight tolerances, eliminate hand-finishing processes and assure part-to-part accuracy at the right first time, which is a limitation of previous approaches.
    • An analytical evaluation of network security modelling techniques applied to manage threats

      Viduto, Valentina; Maple, Carsten; Huang, Wei (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2010)
      The current ubiquity of information coupled with the reliance on such data by businesses has led to a great deal of resources being deployed to ensure the security of this information. Threats can come from a number of sources and the dangers from those insiders closest to the source have increased significantly recently. This paper focuses on techniques used to identify and manage threats as well as the measures that every organisation should consider to put into action. A novel game-based onion skin model has been proposed, combining techniques used in theory-based and hardware-based hardening strategies.
    • Can intelligent optimisation techniques improve computing job scheduling in a Grid environment? review, problem and proposal

      Huang, Wei; French, Tim; Maple, Carsten; Bessis, Nik (NeSC, 2006)
      In the existing Grid scheduling literature, the reported methods and strategies are mostly related to high-level schedulers such as global schedulers, external schedulers, data schedulers, and cluster schedulers. Although a number of these have previously considered job scheduling, thus far only relatively simple queue-based policies such as First In First Out (FIFO) have been considered for local job scheduling within Grid contexts. Our initial research shows that it is worth investigating the potential impact on the performance of the Grid when intelligent optimisation techniques are applied to local scheduling policies. The research problem is defined, and a basic research methodology with a detailed roadmap is presented. This paper forms a proposal with the intention of exchanging ideas and seeking potential collaborators.
    • Comparative study of different approaches to solve batch process scheduling and optimisation problems

      Tan, Yaqing; Huang, Wei; Sun, Yanming; Yue, Yong; University of Bedfordshire (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2012)
      Effective approaches are important to batch process scheduling problems, especially those with complex constraints. However, most research focus on improving optimisation techniques, and those concentrate on comparing their difference are inadequate. This study develops an optimisation model of batch process scheduling problems with complex constraints and investigates the performance of different optimisation techniques, such as Genetic Algorithm (GA) and Constraint Programming (CP). It finds that CP has a better capacity to handle batch process problems with complex constraints but it costs longer time.
    • Comparative study of time-based and activity-based production scheduling

      Das, B.P.; Shah, N.; Chung, Paul Wai Hing; Huang, Wei (University of Pannonia (Hungary), 2000)
      In this paper the principles behind the Time-based and Activity-based approaches to production scheduling are briefly explained. Based on a typical scheduling problem relating to chemicals processing sectors, two schedules using the two different approaches are generated for the purpose of comparison. The first schedule is generated using gBSS, which is a Time-based scheduling software package, which uses mathematical optimisation techniques. The second schedule is produced using BPS, which is a constraint-based scheduler following the principle of the Activity-based approach. A comparison is made between the two schedules considering three different aspects: (1) User input requirements to the problem (2) Quality of the schedule produced (3) Solution statistics. Interestingly, the two schedules produced by the two different approaches are slightly different, although both of them satisfied the product delivery requirements
    • A constraint approach for rescheduling batch processing plants including pipeless plants

      Huang, Wei; Chung, Paul Wai Hing; Loughborough University (Elsevier, 2003)
      In the process industries batch plants are attracting attentions because of their suitability for producing small-volume, high-value added commodity chemicals. Pipeless plants have also been developed and built to increase plant flexibility. Unexpected events, such as the failure of a processing unit, sometimes happen during operations. To avoid risk and to utilise the remaining resource, it is important to reschedule the production operation quickly. The constraint model in BPS has been extended to include constraints for rescheduling. These additional constraints are described in this paper and a case study is used to demonstrate the feasibility of the approach.
    • An experimental investigation of fixture–workpiece contact behaviour for the dynamic simulation of complex fixture–workpiece systems

      Ratchev, Svetan; Phuah, K.; Lämmel, G.; Huang, Wei; University of Nottingham (Elsevier, 2005-05)
      To reduce the overall costs and lead-times of new fixture development, an efficient and accurate fixture design verification methodology would have to be developed. This paper presents an innovative simulation methodology that is capable of predicting the dynamic behaviour of fixture–workpiece systems and is compatible with any commercially available FEA platforms. This is through the implementation of an innovative technique which utilises spring and damper elements to represent every point where the fixture is in contact with the workpiece. Previous verification of the technique has yielded promising results but a key element that needs to be addressed is the description of the spring behaviour in the FEA environment so that it could reflect the real-world behaviour of fixture–workpiece contacts. This paper reports on the experimental work to produce the required spring profiles for a range of fixture and workpiece contact scenarios. The entire experiment was planned and executed using design of experiment (DOE) techniques, ensuring that the results can be tested for statistical significance.
    • A flexible force model for end milling of low-rigidity parts

      Ratchev, Svetan; Liu, Shulong; Huang, Wei; Becker, Adib A.; University of Nottingham (Elsevier, 2004)
      There is a high complexity associated with modelling of cutting forces in machining of thin-wall parts due to the variable part/tool deflection and changing tool immersion angle. The paper reports on a new analytical flexible force model suitable for static machining error compensation of low rigidity components. The model is based on an extended perfect plastic layer model integrated with a finite element model for prediction of part deflection. At each computational step, the flexible force is calculated by taking into account the changes of the immersion angles of the engaged teeth. The material removal process at any infinitesimal segment of the milling cutter teeth is considered as oblique cutting, for which the cutting force is calculated using an orthogonal–oblique transformation. Both the force model and the experimental verifications, use a statistical analysis of the average force. To verify the model the theoretically predicted force is compared with the measured force using a set of cutting trials.
    • Intangible trust requirements - how to fill the requirements trust "gap"?

      French, Tim; Huang, Wei; University of Bedfordshire (Audio Visual Services (A VS), University of Leicester, UK, 2010)
      Previous research efforts have been expended in terms of the capture and subsequent instantiation of "soft" trust requirements that relate to HCI usability concerns or in relation to "hard" tangible security requirements that primarily relate to security a ssurance and security protocols. Little direct focus has been paid to managing intangible trust related requirements per se. This 'gap' is perhaps most evident in the public B2C (Business to Consumer) E- Systems we all use on a daily basis. Some speculative suggestions are made as to how to fill the 'gap'. Visual card sorting is suggested as a suitable evaluative tool; whilst deontic logic trust norms and UML extended notation are the suggested (methodologically invariant) means by which software development teams can perhaps more fully capture hence visualize intangible trust requirements.
    • Integrating routing and scheduling for pipeless plants in different layouts

      Huang, Wei; Chung, Paul Wai Hing; University of Luton; Loughborough University (Elsevier, 2005)
      Pipeless batch plants are built to provide the ability to adapt to fast market changes. The scheduling of pipeless plants adds new challenges to the scheduling of conventional batch plants. This is because of the requirement to consider the allocation of resources and also the plant layout so that vessels can move from one processing station to another without conflict. This research investigates the integrated problem of scheduling and routing in pipeless plants and develops a constraint-based methodology suitable for different layouts. During the scheduling process, besides time and resource allocation, a planner is also called to find possible routes to move vessels from one processing station to the next proposed station. Each of the dynamically generated routes is immediately check for feasible track allocation so that any infeasible route is discarded as soon as possible to save computational time. A typical scheduling problem and results are described in detail to show how this integrated approach works.
    • A lightweight model of trust propagation in a multi-client network environment: to what extent does experience matter?

      Conrad, Marc; French, Tim; Huang, Wei; Maple, Carsten (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2006)
      The increasing growth in the application of global computing and pervasive systems has necessitated careful consideration of security issues. In particular, there has been a growth in the use of electronic communities, in which there exist many relationships between different entities. Such relationships require establishing trust between entities and a great deal of effort has been expended in developing accurate and reliable models of trust in such multi-client environments. Many of these models are complex and not necessarily guaranteed to give accurate trust predictions. In this paper we present a review of some of these models before proposing a simple, lightweight model for trust. The proposed model does not require the estimation of a large parameter set, nor make great assumptions about the parameters that affect trust.
    • Machining simulation and system integration combining FE analysis and cutting mechanics modelling

      Ratchev, Svetan; Liu, Shulong; Huang, Wei; Becker, Adib A. (Springer, 2007-11)
      In this paper, the machining process to produce the right surface profile in machining low-rigidity parts is studied by considering moving dynamic cutting forces that statically and dynamically excite the tool and part reducing the validity of these packages’ output and leading to additional surface errors. The proposed approach is based on producing a simulation environment integrating a data model, an analytical force prediction model, a material removal model and an FE analysis commercial software package. This reported result focuses on the development of the simulation environment and the data model. The integrated environment provides a platform by which FE analysis commercial packages, ABAQUS, can exchange data with the proposed data model, force model and material removal model, to deliver new functionality for machining process simulation where there is force-induced part deflection. The data model includes complete mesh and analysis information for predicting part deflection and enables iterative data updating for multi-step simulation. The proposed simulation methodology has been experimentally validated.
    • A mathematical programming approach to solve the mobile WiMax base station location problem

      Mohammed, A.; Huang, Wei; Zhang, Jie (Pacilantic International, 2010)
    • Milling error prediction and compensation in machining of low-rigidity parts

      Ratchev, Svetan; Liu, Shulong; Huang, Wei; Becker, Adib A.; University of Nottingham (Elsevier, 2004)
      The paper reports on a new integrated methodology for modelling and prediction of surface errors caused by deflection during machining of low-rigidity components. The proposed approach is based on identifying and modelling key processing characteristics that influence part deflection, predicting the workpiece deflection through an adaptive flexible theoretical force-FEA deflection model and providing an input for downstream decision making on error compensation. A new analytical flexible force model suitable for static machining error prediction of low-rigidity components is proposed. The model is based on an extended perfect plastic layer model integrated with a FE model for prediction of part deflection. At each computational step, the flexible force is calculated by taking into account the changes of the immersion angles of the engaged teeth. The material removal process at any infinitesimal segment of the milling cutter teeth is considered as oblique cutting, for which the cutting force is calculated using an orthogonal–oblique transformation. This study aims to increase the understanding of the causes of poor geometric accuracy by considering the impact of the machining forces on the deflection of thin-wall structures. The reported work is a part of an ongoing research for developing an adaptive machining planning environment for surface error modelling and prediction and selection of process and tool path parameters for rapid machining of complex low-rigidity high-accuracy parts.
    • Modelling and simulation environment for machining of low-rigidity components

      Ratchev, Svetan; Huang, Wei; Liu, Shulong; Becker, Adib A.; University of Nottingham (Elsevier, 2004)
      Machining of low-rigidity components is a key process in industries such as aerospace, marine engineering and power engineering. The part deflection caused by the cutting force due to the flexible part structure reduces the validity of the CAM output and leads to additional machining errors that are difficult to predict and control. The paper reports a modelling methodology and integration architecture for multi-step simulation of cutting processes of low-rigidity components incorporating a finite element analysis (FEA)-based component model, FE analysis tool, force model and material removal algorithm. The FEA-based data model of low-rigidity component is proposed based on describing key object-oriented classes such as component, element, node and force to create a common integrated decision making environment. Each object has unique decision making methods associated with it that allow seamless integration in simulating the part behaviour during machining. Two iterative algorithms are proposed within the simulation environment for cutting force prediction and material removal simulation. A prototype version of the simulation environment has been developed using C++, and the feasibility of the proposed approach has been illustrated using practical examples backed up by experimental data.
    • A multi-objective genetic algorithm for minimising network security risk and cost

      Viduto, Valentina; Maple, Carsten; Huang, Wei; Bochenkov, Alexey (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2012)
      Security countermeasures help ensure information security: confidentiality, integrity and availability(CIA), by mitigating possible risks associated with the security event. Due to the fact, that it is often difficult to measure such an impact quantitatively, it is also difficult to deploy appropriate security countermeasures. In this paper, we demonstrate a model of quantitative risk analysis, where an optimisation routine is developed to help a human decision maker to determine the preferred trade-off between investment cost and resulting risk. An offline optimisation routine deploys a genetic algorithm to search for the best countermeasure combination, while multiple risk factors are considered. We conduct an experimentation with real world data, taken from the PTA(Practical Threat Analysis) case study to show that our method is capable of delivering solutions for real world problem data sets. The results show that the multi-objective genetic algorithm (MOGA) approach provides high quality solutions, resulting in better knowledge for decision making.
    • A novel life cycle methodology for web application development in SMEs

      Li, Ru; Huang, Wei; Foskett, David; Cleaver, Vince (Pacilantic International, 2006)
    • A novel risk assessment and optimisation model for a multi-objective network security countermeasure selection problem

      Viduto, Valentina; Maple, Carsten; Huang, Wei; López-Peréz, David (els, 2012-06)
      Budget cuts and the high demand in strengthening the security of computer systems and services constitute a challenge. Poor system knowledge and inappropriate selection of security measures may lead to unexpected financial and data losses. This paper proposes a novel Risk Assessment and Optimisation Model (RAOM) to solve a security countermeasure selection problem, where variables such as financial cost and risk may affect a final decision. A Multi-Objective Tabu Search (MOTS) algorithm has been developed to construct an efficient frontier of non-dominated solutions, which can satisfy organisational security needs in a cost-effective manner.
    • A novel strategy for optimal security investments

      Viduto, Valentina; Huang, Wei; Maple, Carsten; University of Bedfordshire (2010)