A Method for Assessing the Sustainability of Design in Developing World Projects

Projects for the developing world usually find themselves at the bottom of an engineer’s priority list. There is often very little engineering effort placed on creating new products for the poorest people in the world. This trend is beginning to change now as people begin to recognize the potential for these projects. Engineers are beginning to try and solve some of the direst issues in the developing world and many are having positive impacts. However, the conditions needed to support these projects can only be maintained in the short term. There is now a need for greater sustainability. Sustainability has a wide variety of definitions in both business and engineering. These concepts are analyzed and synthesized to develop a broad meaning of sustainability in the developing world. This primarily stems from the “triple bottom line” concept of economic, social, and environmental sustainability. Using this model and several international standards, this thesis develops a metric for guiding and evaluating the sustainability of engineering projects. The metric contains qualitative questions that investigate the sustainability of a project. It is used to assess several existing projects in order to determine flaws. Specifically, three projects seeking to deliver eyeglasses are analyzed for weaknesses to help define a new design approach for achieving better results. Using the metric as a guiding tool, teams designed two pieces of optometry equipment: one to cut lenses for eyeglasses and the other to diagnose refractive error, or prescription. These designs are created and prototyped in the developed and developing worlds in order to determine general feasibility. Although there is a recognized need for eventual design iterations, the whole project is evaluated using the developed metric and compared to the existing projects. Overall, the success demonstrates the improvements made to the long-term sustainability of the project resulting from the use of the sustainability metric.

Multidisciplinary Design Optimization Application to Conceptual Design of University-class Microsatellite Projects

Esta tesis se ha realizado en el contexto del proyecto UPMSat-2, que es un microsatélite diseñado, construido y operado por el Instituto Universitario de Microgravedad "Ignacio Da Riva" (IDR / UPM) de la Universidad Politécnica de Madrid. Aplicación de la metodología Ingeniería Concurrente (Concurrent Engineering: CE) en el marco de la aplicación de diseño multidisciplinar (Multidisciplinary Design Optimization: MDO) es uno de los principales objetivos del presente trabajo. En los últimos años, ha habido un interés continuo en la participación de los grupos de investigación de las universidades en los estudios de la tecnología espacial a través de sus propios microsatélites. La participación en este tipo de proyectos tiene algunos desafíos inherentes, tales como presupuestos y servicios limitados. Además, debido al hecho de que el objetivo principal de estos proyectos es fundamentalmente educativo, por lo general hay incertidumbres en cuanto a su misión en órbita y cargas útiles en las primeras fases del proyecto. Por otro lado, existen limitaciones predeterminadas para sus presupuestos de masa, volumen y energía, debido al hecho de que la mayoría de ellos están considerados como una carga útil auxiliar para el lanzamiento. De este modo, el costo de lanzamiento se reduce considerablemente. En este contexto, el subsistema estructural del satélite es uno de los más afectados por las restricciones que impone el lanzador. Esto puede afectar a diferentes aspectos, incluyendo las dimensiones, la resistencia y los requisitos de frecuencia. En la primera parte de esta tesis, la atención se centra en el desarrollo de una herramienta de diseño del subsistema estructural que evalúa, no sólo las propiedades de la estructura primaria como variables, sino también algunas variables de nivel de sistema del satélite, como la masa de la carga útil y la masa y las dimensiones extremas de satélite. Este enfoque permite que el equipo de diseño obtenga una mejor visión del diseño en un espacio de diseño extendido. La herramienta de diseño estructural se basa en las fórmulas y los supuestos apropiados, incluyendo los modelos estáticos y dinámicos del satélite. Un algoritmo genético (Genetic Algorithm: GA) se aplica al espacio de diseño para optimizaciones de objetivo único y también multiobjetivo. El resultado de la optimización multiobjetivo es un Pareto-optimal basado en dos objetivo, la masa total de satélites mínimo y el máximo presupuesto de masa de carga útil. Por otro lado, la aplicación de los microsatélites en misiones espaciales es de interés por su menor coste y tiempo de desarrollo. La gran necesidad de las aplicaciones de teledetección es un fuerte impulsor de su popularidad en este tipo de misiones espaciales. Las misiones de tele-observación por satélite son esenciales para la investigación de los recursos de la tierra y el medio ambiente. En estas misiones existen interrelaciones estrechas entre diferentes requisitos como la altitud orbital, tiempo de revisita, el ciclo de vida y la resolución. Además, todos estos requisitos puede afectar a toda las características de diseño. Durante los últimos años la aplicación de CE en las misiones espaciales ha demostrado una gran ventaja para llegar al diseño óptimo, teniendo en cuenta tanto el rendimiento y el costo del proyecto. Un ejemplo bien conocido de la aplicación de CE es la CDF (Facilidad Diseño Concurrente) de la ESA (Agencia Espacial Europea). Está claro que para los proyectos de microsatélites universitarios tener o desarrollar una instalación de este tipo parece estar más allá de las capacidades del proyecto. Sin embargo, la práctica de la CE a cualquier escala puede ser beneficiosa para los microsatélites universitarios también. En la segunda parte de esta tesis, la atención se centra en el desarrollo de una estructura de optimización de diseño multidisciplinar (Multidisciplinary Design Optimization: MDO) aplicable a la fase de diseño conceptual de microsatélites de teledetección. Este enfoque permite que el equipo de diseño conozca la interacción entre las diferentes variables de diseño. El esquema MDO presentado no sólo incluye variables de nivel de sistema, tales como la masa total del satélite y la potencia total, sino también los requisitos de la misión como la resolución y tiempo de revisita. El proceso de diseño de microsatélites se divide en tres disciplinas; a) diseño de órbita, b) diseño de carga útil y c) diseño de plataforma. En primer lugar, se calculan diferentes parámetros de misión para un rango práctico de órbitas helio-síncronas (sun-synchronous orbits: SS-Os). Luego, según los parámetros orbitales y los datos de un instrumento como referencia, se calcula la masa y la potencia de la carga útil. El diseño de la plataforma del satélite se estima a partir de los datos de la masa y potencia de los diferentes subsistemas utilizando relaciones empíricas de diseño. El diseño del subsistema de potencia se realiza teniendo en cuenta variables de diseño más detalladas, como el escenario de la misión y diferentes tipos de células solares y baterías. El escenario se selecciona, de modo de obtener una banda de cobertura sobre la superficie terrestre paralelo al Ecuador después de cada intervalo de revisita. Con el objetivo de evaluar las interrelaciones entre las diferentes variables en el espacio de diseño, todas las disciplinas de diseño mencionados se combinan en un código unificado. Por último, una forma básica de MDO se ajusta a la herramienta de diseño de sistema de satélite. La optimización del diseño se realiza por medio de un GA con el único objetivo de minimizar la masa total de microsatélite. Según los resultados obtenidos de la aplicación del MDO, existen diferentes puntos de diseños óptimos, pero con diferentes variables de misión. Este análisis demuestra la aplicabilidad de MDO para los estudios de ingeniería de sistema en la fase de diseño conceptual en este tipo de proyectos. La principal conclusión de esta tesis, es que el diseño clásico de los satélites que por lo general comienza con la definición de la misión y la carga útil no es necesariamente la mejor metodología para todos los proyectos de satélites. Un microsatélite universitario, es un ejemplo de este tipo de proyectos. Por eso, se han desarrollado un conjunto de herramientas de diseño para encarar los estudios de la fase inicial de diseño. Este conjunto de herramientas incluye diferentes disciplinas de diseño centrados en el subsistema estructural y teniendo en cuenta una carga útil desconocida a priori. Los resultados demuestran que la mínima masa total del satélite y la máxima masa disponible para una carga útil desconocida a priori, son objetivos conflictivos. En este contexto para encontrar un Pareto-optimal se ha aplicado una optimización multiobjetivo. Según los resultados se concluye que la selección de la masa total por satélite en el rango de 40-60 kg puede considerarse como óptima para un proyecto de microsatélites universitario con carga útil desconocida a priori. También la metodología CE se ha aplicado al proceso de diseño conceptual de microsatélites de teledetección. Los resultados de la aplicación del CE proporcionan una clara comprensión de la interacción entre los requisitos de diseño de sistemas de satélites, tales como la masa total del microsatélite y la potencia y los requisitos de la misión como la resolución y el tiempo de revisita. La aplicación de MDO se hace con la minimización de la masa total de microsatélite. Los resultados de la aplicación de MDO aclaran la relación clara entre los diferentes requisitos de diseño del sistema y de misión, así como que permiten seleccionar las líneas de base para el diseño óptimo con el objetivo seleccionado en las primeras fase de diseño. ABSTRACT This thesis is done in the context of UPMSat-2 project, which is a microsatellite under design and manufacturing at the Instituto Universitario de Microgravedad “Ignacio Da Riva” (IDR/UPM) of the Universidad Politécnica de Madrid. Application of Concurrent Engineering (CE) methodology in the framework of Multidisciplinary Design application (MDO) is one of the main objectives of the present work. In recent years, there has been continuing interest in the participation of university research groups in space technology studies by means of their own microsatellites. The involvement in such projects has some inherent challenges, such as limited budget and facilities. Also, due to the fact that the main objective of these projects is for educational purposes, usually there are uncertainties regarding their in orbit mission and scientific payloads at the early phases of the project. On the other hand, there are predetermined limitations for their mass and volume budgets owing to the fact that most of them are launched as an auxiliary payload in which the launch cost is reduced considerably. The satellite structure subsystem is the one which is most affected by the launcher constraints. This can affect different aspects, including dimensions, strength and frequency requirements. In the first part of this thesis, the main focus is on developing a structural design sizing tool containing not only the primary structures properties as variables but also the satellite system level variables such as payload mass budget and satellite total mass and dimensions. This approach enables the design team to obtain better insight into the design in an extended design envelope. The structural design sizing tool is based on the analytical structural design formulas and appropriate assumptions including both static and dynamic models of the satellite. A Genetic Algorithm (GA) is applied to the design space for both single and multiobejective optimizations. The result of the multiobjective optimization is a Pareto-optimal based on two objectives, minimum satellite total mass and maximum payload mass budget. On the other hand, the application of the microsatellites is of interest for their less cost and response time. The high need for the remote sensing applications is a strong driver of their popularity in space missions. The satellite remote sensing missions are essential for long term research around the condition of the earth resources and environment. In remote sensing missions there are tight interrelations between different requirements such as orbital altitude, revisit time, mission cycle life and spatial resolution. Also, all of these requirements can affect the whole design characteristics. During the last years application of the CE in the space missions has demonstrated a great advantage to reach the optimum design base lines considering both the performance and the cost of the project. A well-known example of CE application is ESA (European Space Agency) CDF (Concurrent Design Facility). It is clear that for the university-class microsatellite projects having or developing such a facility seems beyond the project capabilities. Nevertheless practicing CE at any scale can be beneficiary for the university-class microsatellite projects. In the second part of this thesis, the main focus is on developing a MDO framework applicable to the conceptual design phase of the remote sensing microsatellites. This approach enables the design team to evaluate the interaction between the different system design variables. The presented MDO framework contains not only the system level variables such as the satellite total mass and total power, but also the mission requirements like the spatial resolution and the revisit time. The microsatellite sizing process is divided into the three major design disciplines; a) orbit design, b) payload sizing and c) bus sizing. First, different mission parameters for a practical range of sun-synchronous orbits (SS-Os) are calculated. Then, according to the orbital parameters and a reference remote sensing instrument, mass and power of the payload are calculated. Satellite bus sizing is done based on mass and power calculation of the different subsystems using design estimation relationships. In the satellite bus sizing, the power subsystem design is realized by considering more detailed design variables including a mission scenario and different types of solar cells and batteries. The mission scenario is selected in order to obtain a coverage belt on the earth surface parallel to the earth equatorial after each revisit time. In order to evaluate the interrelations between the different variables inside the design space all the mentioned design disciplines are combined in a unified code. The integrated satellite system sizing tool developed in this section is considered as an application of the CE to the conceptual design of the remote sensing microsatellite projects. Finally, in order to apply the MDO methodology to the design problem, a basic MDO framework is adjusted to the developed satellite system design tool. Design optimization is done by means of a GA single objective algorithm with the objective function as minimizing the microsatellite total mass. According to the results of MDO application, there exist different optimum design points all with the minimum satellite total mass but with different mission variables. This output demonstrates the successful applicability of MDO approach for system engineering trade-off studies at the conceptual design phase of the design in such projects. The main conclusion of this thesis is that the classical design approach for the satellite design which usually starts with the mission and payload definition is not necessarily the best approach for all of the satellite projects. The university-class microsatellite is an example for such projects. Due to this fact an integrated satellite sizing tool including different design disciplines focusing on the structural subsystem and considering unknown payload is developed. According to the results the satellite total mass and available mass for the unknown payload are conflictive objectives. In order to find the Pareto-optimal a multiobjective GA optimization is conducted. Based on the optimization results it is concluded that selecting the satellite total mass in the range of 40-60 kg can be considered as an optimum approach for a university-class microsatellite project with unknown payload(s). Also, the CE methodology is applied to the remote sensing microsatellites conceptual design process. The results of CE application provide a clear understanding of the interaction between satellite system design requirements such as satellite total mass and power and the satellite mission variables such as revisit time and spatial resolution. The MDO application is done with the total mass minimization of a remote sensing satellite. The results from the MDO application clarify the unclear relationship between different system and mission design variables as well as the optimum design base lines according to the selected objective during the initial design phases.

Funicularity and equilibrium for high-performance conceptual structural design

Las estructuras que trabajan por forma se caracterizan por la íntima e indisociable relación entre geometría y comportamiento estructural. Por consiguiente, la elección de una apropiada geometría es el paso previo indispensable en el diseño conceptual de dichas estructuras. En esa tarea, la selección de las posibles geometrías antifuniculares para las distribuciones de cargas permanentes más habituales son más bien limitadas y, muchas veces, son criterios no estructurales (adaptabilidad funcional, estética, proceso constructivo, etc.) los que no permiten la utilización de dichas geometrías que garantizarían el máximo aprovechamiento del material. En este contexto, esta tesis estudia la posibilidad de obtener una estructura sin momentos flectores incluso si la geometría no es antifunicular para sus cargas permanentes. En efecto, esta tesis presenta un procedimiento, basado en la estática gráfica, que demuestra cómo un conjunto de cargas adicionales, introducidas a través de un sistema de pretensado exterior con elementos post-tesos, puede eliminar los momentos flectores debidos a cargas permanentes en cualquier geometría plana. Esto se traduce en una estructura antifunicular que proporciona respuestas innovadoras a demandas conjuntas de versatilidad arquitectónica y optimización del material. Dicha metodología gráfica ha sido implementada en un software distribuido libremente (EXOEQUILIBRIUM), donde el análisis estructural y la variación geométrica están incluidos en el mismo entorno interactivo y paramétrico. La utilización de estas herramientas permite más versatilidad en la búsqueda de nuevas formas eficientes, lo cual tiene gran importancia en el diseño conceptual de estructuras, liberando al ingeniero de la limitación del propio cálculo y de la incomprensión del comportamiento estructural, facilitando extraordinariamente el hecho creativo a la luz de una metodología de este estilo. Esta tesis incluye la aplicación de estos procedimientos a estructuras de cualquier geometría y distribución inicial de cargas, así como el estudio de diferentes posibles criterios de diseño para optimizar la posición del sistema de post-tesado. Además, la metodología ha sido empleada en el proyecto de maquetas a escala reducida y en la construcción de un pabellón hecho enteramente de cartón, lo que ha permitido obtener una validación física del procedimiento desarrollado. En definitiva, esta tesis expande de manera relevante el rango de posibles geometrías antifuniculares y abre enormes posibilidades para el diseño de estructuras que combinan eficiencia estructural y flexibilidad arquitectónica.Curved structures are characterized by the critical relationship between their geometry and structural behaviour, and selecting an appropriate shape in the conceptual design of such structures is important for achieving materialefficiency. However, the set of bending-free geometries are limited and, often, non-structural design criteria (e.g., usability, architectural needs, aesthetics) prohibit the selection of purely funicular or antifunicular shapes. In response to this issue, this thesis studies the possibility of achieving an axial-only behaviour even if the geometry departs from the ideally bending-free shape. This dissertation presents a new design approach, based on graphic statics that shows how bending moments in a two-dimensional geometry can be eliminated by adding forces through an external post-tensioning system. This results in bending-free structures that provide innovative answers to combined demands on versatility and material optimization. The graphical procedure has been implemented in a free-downloadable design-driven software (EXOEQUILIBRIUM) where structural performance evaluations and geometric variation are embedded within an interactive and parametric working environment. This provides greater versatility in finding new efficient structural configurations during the first design stages, bridging the gap between architectural shaping and structural analysis. The thesis includes the application of the developed graphical procedure to shapes with random curvature and distribution of loads. Furthermore, the effect of different design criteria on the internal force distribution has been analyzed. Finally, the construction of reduced- and large-scale models provides further physical validation of the method and insights about the structural behaviour of these structures. In summary, this work strongly expands the range of possible forms that exhibit a bending-free behaviour and, de facto, opens up new possibilities for designs that combine high-performing solutions with architectural freedom.

Conversion of a maltose receptor into a zinc biosensor by computational design

We have demonstrated that it is possible to radically change the specificity of maltose binding protein by converting it into a zinc sensor using a rational design approach. In this new molecular sensor, zinc binding is transduced into a readily detected fluorescence signal by use of an engineered conformational coupling mechanism linking ligand binding to reporter group response. An iterative progressive design strategy led to the construction of variants with increased zinc affinity by combining binding sites, optimizing the primary coordination sphere, and exploiting conformational equilibria. Intermediates in the design series show that the adaptive process involves both introduction and optimization of new functions and removal of adverse vestigial interactions. The latter demonstrates the importance of the rational design approach in uncovering cryptic phenomena in protein function, which cannot be revealed by the study of naturally evolved systems.

SITE 1121 - FIELD NOTES Revealing Deep Form as a Basis for Urban Landscape Design

Thesis (Master's)--University of Washington, 2016-06

A participatory design agenda for ubiquitous computing and multimodal interaction: A case study of dental practice

This paper reflects upon our attempts to bring a participatory design approach to design research into interfaces that better support dental practice. The project brought together design researchers, general and specialist dental practitioners, the CEO of a dental software company and, to a limited extent, dental patients. We explored the potential for deployment of speech and gesture technologies in the challenging and authentic context of dental practices. The paper describes the various motivations behind the project, the negotiation of access and the development of the participant relationships as seen from the researchers' perspectives. Conducting participatory design sessions with busy professionals demands preparation, improvisation, and clarity of purpose. The paper describes how we identified what went well and when to shift tactics. The contribution of the paper is in its description of what we learned in bringing participatory design principles to a project that spanned technical research interests, commercial objectives and placing demands upon the time of skilled professionals. Copyright © 2010 ACM, Inc

Pragmatic approach to the development of robust real-time protocols

This research is concerned with the development of distributed real-time systems, in which software is used for the control of concurrent physical processes. These distributed control systems are required to periodically coordinate the operation of several autonomous physical processes, with the property of an atomic action. The implementation of this coordination must be fault-tolerant if the integrity of the system is to be maintained in the presence of processor or communication failures. Commit protocols have been widely used to provide this type of atomicity and ensure consistency in distributed computer systems. The objective of this research is the development of a class of robust commit protocols, applicable to the coordination of distributed real-time control systems. Extended forms of the standard two phase commit protocol, that provides fault-tolerant and real-time behaviour, were developed. Petri nets are used for the design of the distributed controllers, and to embed the commit protocol models within these controller designs. This composition of controller and protocol model allows the analysis of the complete system in a unified manner. A common problem for Petri net based techniques is that of state space explosion, a modular approach to both the design and analysis would help cope with this problem. Although extensions to Petri nets that allow module construction exist, generally the modularisation is restricted to the specification, and analysis must be performed on the (flat) detailed net. The Petri net designs for the type of distributed systems considered in this research are both large and complex. The top down, bottom up and hybrid synthesis techniques that are used to model large systems in Petri nets are considered. A hybrid approach to Petri net design for a restricted class of communicating processes is developed. Designs produced using this hybrid approach are modular and allow re-use of verified modules. In order to use this form of modular analysis, it is necessary to project an equivalent but reduced behaviour on the modules used. These projections conceal events local to modules that are not essential for the purpose of analysis. To generate the external behaviour, each firing sequence of the subnet is replaced by an atomic transition internal to the module, and the firing of these transitions transforms the input and output markings of the module. Thus local events are concealed through the projection of the external behaviour of modules. This hybrid design approach preserves properties of interest, such as boundedness and liveness, while the systematic concealment of local events allows the management of state space. The approach presented in this research is particularly suited to distributed systems, as the underlying communication model is used as the basis for the interconnection of modules in the design procedure. This hybrid approach is applied to Petri net based design and analysis of distributed controllers for two industrial applications that incorporate the robust, real-time commit protocols developed. Temporal Petri nets, which combine Petri nets and temporal logic, are used to capture and verify causal and temporal aspects of the designs in a unified manner.

Network lifetime maximization with cross-layer design in wireless sensor networks

This paper investigates a cross-layer design approach for minimizing energy consumption and maximizing network lifetime (NL) of a multiple-source and single-sink (MSSS) WSN with energy constraints. The optimization problem for MSSS WSN can be formulated as a mixed integer convex optimization problem with the adoption of time division multiple access (TDMA) in medium access control (MAC) layer, and it becomes a convex problem by relaxing the integer constraint on time slots. Impacts of data rate, link access and routing are jointly taken into account in the optimization problem formulation. Both linear and planar network topologies are considered for NL maximization (NLM). With linear MSSS and planar single-source and single-sink (SSSS) topologies, we successfully use Karush-Kuhn-Tucker (KKT) optimality conditions to derive analytical expressions of the optimal NL when all nodes are exhausted simultaneously. The problem for planar MSSS topology is more complicated, and a decomposition and combination (D&C) approach is proposed to compute suboptimal solutions. An analytical expression of the suboptimal NL is derived for a small scale planar network. To deal with larger scale planar network, an iterative algorithm is proposed for the D&C approach. Numerical results show that the upper-bounds of the network lifetime obtained by our proposed optimization models are tight. Important insights into the NL and benefits of cross-layer design for WSN NLM are obtained.

Practical design considerations of cascaded hybrid battery storage systems

The high cost of batteries has led to investigations in using second-life ex-transportation batteries for grid support applications. Vehicle manufacturers currently all have different specifications for battery chemistry, arrangement of cells, capacity and voltage. With anticipated new developments in battery chemistry which could also affect these parameters, there are, as yet, no standards defining parameters in second life applications. To overcome issues relating to sizing and to prevent future obsolescence for the rest of the energy storage system, a cascaded topology with an operating envelope design approach has been used to connect together modules. This topology offers advantages in terms of system reliability. The design methodology is validated through a set of experimental results resulting in the creation of surface maps looking at the operation of the converter (efficiency and inductor ripple current). The use of a pre-defined module operating envelope also offers advantages for developing new operational strategies for systems with both hybrid battery energy systems and also hybrid systems including other energy sources such as solar power.

Practice based learning for automotive engineering design students

The automotive industry combines a multitude of professionals to develop a modern car successfully. Within the design and development teams the collaboration and interface between Engineers and Designers is critical to ensure design intent is communicated and maintained throughout the development process. This study highlights recent industry practice with the emergence of Concept Engineers in design teams at Jaguar Land Rover Automotive group. The role of the Concept Engineer emphasises the importance of the Engineering and Design/Styling interface with the Concept engineer able to interact and understand the challenges and specific languages of each specialist area, hence improving efficiency and communication within the design team. Automotive education tends to approach design from two distinct directions, that of engineering design through BSc courses or a more styling design approach through BA and BDes routes. The educational challenge for both types of course is to develop engineers and stylist's who have greater understanding and experience of each other's specialist perspective of design and development. The study gives examples of two such courses in the UK who are developing programmes to help students widen their understanding of the engineering and design spectrum. Initial results suggest the practical approach has been well received by students and encouraged by industry as they seek graduates with specialist knowledge but also a wider appreciation of their role within the design process.

An aspect-oriented approach to designing role-based access control services

Access control (AC) limits access to the resources of a system only to authorized entities. Given that information systems today are increasingly interconnected, AC is extremely important. The implementation of an AC service is a complicated task. Yet the requirements to an AC service vary a lot. Accordingly, the design of an AC service should be flexible and extensible in order to save development effort and time. Unfortunately, with conventional object-oriented techniques, when an extension has not been anticipated at the design time, the modification incurred by the extension is often invasive. Invasive changes destroy design modularity, further deteriorate design extensibility, and even worse, they reduce product reliability. ^ A concern is crosscutting if it spans multiple object-oriented classes. It was identified that invasive changes were due to the crosscutting nature of most unplanned extensions. To overcome this problem, an aspect-oriented design approach for AC services was proposed, as aspect-oriented techniques could effectively encapsulate crosscutting concerns. The proposed approach was applied to develop an AC framework that supported role-based access control model. In the framework, the core role-based access control mechanism is given in an object-oriented design, while each extension is captured as an aspect. The resulting framework is well-modularized, flexible, and most importantly, supports noninvasive adaptation. ^ In addition, a process to formalize the aspect-oriented design was described. The purpose is to provide high assurance for AC services. Object-Z was used to specify the static structure and Predicate/Transition net was used to model the dynamic behavior. Object-Z was extended to facilitate specification in an aspect-oriented style. The process of formal modeling helps designers to enhance their understanding of the design, hence to detect problems. Furthermore, the specification can be mathematically verified. This provides confidence that the design is correct. It was illustrated through an example that the model was ready for formal analysis. ^

Design of experiments to study the impact of process parameters on droplet size and development of non-invasive imaging techniques in tablet coating

Atomisation of an aqueous solution for tablet film coating is a complex process with multiple factors determining droplet formation and properties. The importance of droplet size for an efficient process and a high quality final product has been noted in the literature, with smaller droplets reported to produce smoother, more homogenous coatings whilst simultaneously avoiding the risk of damage through over-wetting of the tablet core. In this work the effect of droplet size on tablet film coat characteristics was investigated using X-ray microcomputed tomography (XμCT) and confocal laser scanning microscopy (CLSM). A quality by design approach utilising design of experiments (DOE) was used to optimise the conditions necessary for production of droplets at a small (20 μm) and large (70 μm) droplet size. Droplet size distribution was measured using real-time laser diffraction and the volume median diameter taken as a response. DOE yielded information on the relationship three critical process parameters: pump rate, atomisation pressure and coating-polymer concentration, had upon droplet size. The model generated was robust, scoring highly for model fit (R2 = 0.977), predictability (Q2 = 0.837), validity and reproducibility. Modelling confirmed that all parameters had either a linear or quadratic effect on droplet size and revealed an interaction between pump rate and atomisation pressure. Fluidised bed coating of tablet cores was performed with either small or large droplets followed by CLSM and XμCT imaging. Addition of commonly used contrast materials to the coating solution improved visualisation of the coating by XμCT, showing the coat as a discrete section of the overall tablet. Imaging provided qualitative and quantitative evidence revealing that smaller droplets formed thinner, more uniform and less porous film coats.

The effect of personality on the design team:lessons from industry for design education

This study examines the effect of individual character types in design teams through case studies at ARUP associates and five United Kingdom university design degree programmes. By observing an individual's approach and contribution within a team, patterns of design behaviour are highlighted and compared within the industrial and academic examples. Initial findings have identified discreet differences in design approach and ways of working. By identifying these initial character clusters, design behaviour can be predicted to help teams and individuals to strengthen their design process. This research brings together: 1. The design process and how engineering and design teams work to solve problems. 2. The natural characteristics of individuals and how they approach problems. This difference of approach can be viewed in relation to the design process where engineers and designers will recognise their preference for certain stages of the design process. This study suggests that these individual preferences are suited to different stages of the design process, and that industry uses teams to ensure a broad range of views, an approach design education would do well to apply by establishing collaborative input in the design process.

The framework for REVIEWS: an exploration into design principles for an electronic medical early warning system observation chart

The observation chart is for many health professionals (HPs) the primary source of objective information relating to the health of a patient. Information Systems (IS) research has demonstrated the positive impact of good interface design on decision making and it is logical that good observation chart design can positively impact healthcare decision making. Despite the potential for good observation chart design, there is a paucity of observation chart design literature, with the primary source of literature leveraging Human Computer Interaction (HCI) literature to design better charts. While this approach has been successful, this design approach introduces a gap between understanding of the tasks performed by HPs when using charts and the design features implemented in the chart. Good IS allow for the collection and manipulation of data so that it can be presented in a timely manner that support specific tasks. Good interface design should therefore consider the specific tasks being performed prior to designing the interface. This research adopts a Design Science Research (DSR) approach to formalise a framework of design principles that incorporates knowledge of the tasks performed by HPs when using observation charts and knowledge pertaining to visual representations of data and semiology of graphics. This research is presented in three phases, the initial two phases seek to discover and formalise design knowledge embedded in two situated observation charts: the paper-based NEWS chart developed by the Health Service Executive in Ireland and the electronically generated eNEWS chart developed by the Health Information Systems Research Centre in University College Cork. A comparative evaluation of each chart is also presented in the respective phases. Throughout each of these phases, tentative versions of a design framework for electronic vital sign observation charts are presented, with each subsequent iteration of the framework (versions Alpha, Beta, V0.1 and V1.0) representing a refinement of the design knowledge. The design framework will be named the framework for the Retrospective Evaluation of Vital Sign Information from Early Warning Systems (REVIEWS). Phase 3 of the research presents the deductive process for designing and implementing V0.1 of the framework, with evaluation of the instantiation allowing for the final iteration V1.0 of the framework. This study makes a number of contributions to academic research. First the research demonstrates that the cognitive tasks performed by nurses during clinical reasoning can be supported through good observation chart design. Secondly the research establishes the utility of electronic vital sign observation charts in terms of supporting the cognitive tasks performed by nurses during clinical reasoning. Third the framework for REVIEWS represents a comprehensive set of design principles which if applied to chart design will improve the usefulness of the chart in terms of supporting clinical reasoning. Fourth the electronic observation chart that emerges from this research is demonstrated to be significantly more useful than previously designed charts and represents a significant contribution to practice. Finally the research presents a research design that employs a combination of inductive and deductive design activities to iterate on the design of situated artefacts.

Constraint-force-based approach of modelling compliant mechanisms: principle and application

Numerous works have been conducted on modelling basic compliant elements such as wire beams, and closed-form analytical models of most basic compliant elements have been well developed. However, the modelling of complex compliant mechanisms is still a challenging work. This paper proposes a constraint-force-based (CFB) modelling approach to model compliant mechanisms with a particular emphasis on modelling complex compliant mechanisms. The proposed CFB modelling approach can be regarded as an improved free-body- diagram (FBD) based modelling approach, and can be extended to a development of the screw-theory-based design approach. A compliant mechanism can be decomposed into rigid stages and compliant modules. A compliant module can offer elastic forces due to its deformation. Such elastic forces are regarded as variable constraint forces in the CFB modelling approach. Additionally, the CFB modelling approach defines external forces applied on a compliant mechanism as constant constraint forces. If a compliant mechanism is at static equilibrium, all the rigid stages are also at static equilibrium under the influence of the variable and constant constraint forces. Therefore, the constraint force equilibrium equations for all the rigid stages can be obtained, and the analytical model of the compliant mechanism can be derived based on the constraint force equilibrium equations. The CFB modelling approach can model a compliant mechanism linearly and nonlinearly, can obtain displacements of any points of the rigid stages, and allows external forces to be exerted on any positions of the rigid stages. Compared with the FBD based modelling approach, the CFB modelling approach does not need to identify the possible deformed configuration of a complex compliant mechanism to obtain the geometric compatibility conditions and the force equilibrium equations. Additionally, the mathematical expressions in the CFB approach have an easily understood physical meaning. Using the CFB modelling approach, the variable constraint forces of three compliant modules, a wire beam, a four-beam compliant module and an eight-beam compliant module, have been derived in this paper. Based on these variable constraint forces, the linear and non-linear models of a decoupled XYZ compliant parallel mechanism are derived, and verified by FEA simulations and experimental tests.