Mapping customer needs to engineering characteristics: an aerospace perspective for conceptual design

Designing complex engineering systems, such as an aircraft or an aero-engine, is immensely challenging. Formal Systems Engineering (SE) practices are widely used in the aerospace industry throughout the overall design process to minimise the overall design effort, corrective re-work, and ultimately overall development and manufacturing costs. Incorporating the needs and requirements from customers and other stakeholders into the conceptual and early design process is vital for the success and viability of any development programme. This paper presents a formal methodology, the Value-Driven Design (VDD) methodology that has been developed for collaborative and iterative use in the Extended Enterprise (EE) within the aerospace industry, and that has been applied using the Concept Design Analysis (CODA) method to map captured Customer Needs (CNs) into Engineering Characteristics (ECs) and to model an overall ‘design merit’ metric to be used in design assessments, sensitivity analyses, and engineering design optimisation studies. Two different case studies with increasing complexity are presented to elucidate the application areas of the CODA method in the context of the VDD methodology for the EE within the aerospace secto

Closing the communications loop on the computerized peer‐assessment of essays

The use of self‐ and peer‐assessment is not new to higher education. Traditionally its use has required the complex and time‐consuming management of coursework submissions by the tutor, in an attempt to maintain validity and anonymity of the assessment process. In the last few years a number of computerized systems have been developed that are capable of automatically supporting, managing and performing the assessment process. The requirement for student anonymity and the release of the tutor from the process of marking have reduced the ability to develop the iterative process of feedback. This feedback is considered essential in supporting student learning and developing reflective practice. This paper describes the enhancement of a computerized assessment system to support anonymous computer‐mediated discussion between marker and marked having previously performed peer‐assessment. A detailed description is provided of the integrated assessment process, and an analysis of the use of this anonymous discussion is presented. Anonymous student feedback is presented and analyzed with respect to the perceived benefits of using the system with respect to enhancing the student learning process

Three-dimensional direct numerical simulation of surface-tension-gradient effects on the leveling of an evaporating multicomponent fluid

Mathematical and numerical modeling of drying coating layers is of interest to both industrial and academic communities. Compositional changes that occur during the drying process make the implementation of practical and efficient numerical models rather difficult. In this paper we present a three-dimensional mathematical and numerical model based on the lubrication approximation for the flow of drying paint films on horizontal substrates. The paint is modeled as a multicomponent liquid with one nonvolatile and one volatile component, termed the "resin" and the "solvent" respectively. Our model includes the effects of surface tension and gravitational forces as well as surface tension gradient effects which arise due to solvent evaporation. The dependence of viscosity, diffusivity, and evaporation rate on resin concentration is also incorporated in the model. A closed-form Linearized solution has been found for coating layers that are of almost uniform thickness. The numerical solution agrees closely with the linear solution in the appropriate Limit. A model simulation demonstrates the effect of surface tension gradients due to compositional changes in a three-dimensional flow field, and we suggest methods by which these gradients may be used to obtain a more uniform final coating layer

Short message service in a grid-enabled computing environment

Mobile computing devices such as mobile phones together with a land-based and wireless communication network infrastructure are the existing technical prerequisites for continuous access to networked services. The security of the system is a high concern in this environment, as well as its usability. This paper presents a network infrastructure for using the Short Message Service (SMS) to communicate with mobile phones via a grid-enabled service. The network system includes: a messenger server, a messenger client, Globus Servers and the Short Message Service Centre (SMSC) tied together with XML-RPC, TCP/IP and GRAM protocols for communication. A Matlab tool to use the grid-enabled SMS has been implemented and we demonstrate its use in a grid-enabled application

An improvement of the concept design analysis method by the use of the avoidance function

Avoiding disasters due to resonance is a major concern in construction projects such as buildings, bridges and pipelines. This paper uses the Concept Design Analysis (CODA) method that is capable of supporting the described Value-Driven Design (VDD) methodology. While VDD promotes the use of a system wide ‘value’ function during conceptual design, the CODA method allows mapping customer needs into engineering characteristics in order to calculate a single normalized design metric. The CODA method employs three different merit functions: maximizing (more is better), minimizing (less is better), and optimizing (target is better). This paper proposes a new merit function called avoidance function that allows excluding a range of engineering characteristics, e.g. avoiding a range of resonant frequencies. An example of a simple CODA model for a bicycle wheel design selection with the proposed the avoidance function is presented

Fingering phenomena for driven coating films

A theoretical and numerical model is formulated to describe the instability and the long-time evolution of both gravity-driven and surface-shear-stress-driven thin coating films. A single evolution equation, of higher-order diffusive type, models the flow for either problem. It is derived using the lubrication approximation. For partially wetting systems, the effect of finite contact angle is incorporated in the equation using a particular disjoining pressure model. The base state, in each case, is a two-dimensional steadily propagating capillary front. Slight perturbations of the base state, applied along the front, initiate the fingering instability. Early-time results accurately reproduce the wavelengths of fastest growth and the corresponding eigenmodes as reported in published linear stability analyses. As time proceeds, depending on parameter values, various fingering patterns arise. For conditions of perfect wetting with the substrate downstream of the moving front covered with a thin precursor layer, predicted nonlinear finger evolution agrees well with published experiments. The ultimate pattern, in this case, is a steadily translating pattern of wedge-shaped fingers. Alternatively, for partially wetting systems that exhibit sufficiently large static contact angles, long straight-sided fingers or rivulets are formed. Finally, for larger contact angles, or at relatively low speeds, we predict that the flowing rivulets will become unstable and break up into strings of isolated droplets

A grid-enabled problem solving environment (PSE) for design optimisation within matlab

The process of design search and optimisation using Computational Fluid Dynamics (CFD) is computationally and data intensive, a problem well-suited to Grid computing. The Geodise toolkit is a suite of Grid-enabled design optimisation and search tools within the Matlab environment. The use of these tools by the engineer is facilitated by intelligent design advisers targeted initially at CFD. The role of remote computation and data access in constructing a Grid-enabled Problem Solving Environment is discussed. The use of the Geodise toolkit for design optimisation from within the Matlab environment is considered with an exemplar problem

An integrated life cycle cost tool for aero-engines

The shift of aero-engine manufacturers to provide services rather than products has made the consideration of life cycle performance increasingly vital. This work looks into the practical aspects of developing design tools to predict Life Cycle Costs (LCC). As the calculation of LCC involves a highly diverse set of representations and processes, it is undesirable to use a single software tool to undertake this task. This work seeks to demonstrate how different modelling paradigms should be used in tandem to produce an elegant solution. An integrated tool which links engine component unit costs and probabilistic failure mechanism lives to maintenance costs is presented. Finally, the need for a framework which supports easy construction of specific rather than generic LCC models is identified and discussed

Grid middleware for engineering design search and optimisation.

Design search and optimisation algorithms can be used by engineers to yield improved designs. Design search involving the analysis of the aerodynamic properties of a design, using Computational Fluid Dynamics, is both computationally and data intensive, making this problem well matched to Grid computing. Evaluation of the quality of a design (the objective function) may require commercial and user supplied software packages to be called in sequence, data transferred to and from suitable compute resources, in addition to pre- and post-processing. To allow engineers to express these necessarily complex workflows we expose a suite of Grid-enabled tools to a high-level scripting language. These tools include client functionality to Globus compute resources, and to a job submission Web service which exposes a cycle-scavenging Condor pool. These tools are exposed as functions to the Matlab environment that can be used directly by the engineer, or integrated into higher level functions for design search and optimisation. Here the benefits of the scripting approach are discussed, together with details of the Grid middleware used and the implementation of the client functionality

User deployment of grid toolkits to engineers

Recently a full-scale deployment of the Geodise toolboxes has been performed in the Computational Engineering and Design Centre, University of Southampton. This deployment included the following steps: installation of required software components such as Globus, Condor, Oracle, and Webspere Application Server; installation of Geodise tools; configuring available software packages; training researchers via documents and workshops; and administering the whole infrastructure. In this paper we present our hands-on experience from deploying the toolboxes along with the challenges that may arise while Grid-enabling an existing computational cluster of an organisation. A special emphasis will be given to problems and proposed solutions of accessing COndor pools across a NAT firewall using the existing Grid infrastructure