1,488 research outputs found
Multi-objective new product development by complete Pareto front and ripple-spreading algorithm
No full textGiven several different new product development projects and limited resources, this paper is concerned with the optimal allocation of resources among the projects. This is clearly a multi-objective optimization problem (MOOP), because each new product development project has both a profit expectation and a loss expectation, and such expectations vary according to allocated resources. In such a case, the goal of multi-objective new product development (MONPD) is to maximize the profit expectation while minimizing the loss expectation. As is well known, Pareto optimality and the Pareto front are extremely important to resolve MOOPs. Unlike many other MOOP methods which provide only a single Pareto optimal solution or an approximation of the Pareto front, this paper reports a novel method to calculate the complete Pareto front for the MONPD. Some theoretical conditions and a ripple-spreading algorithm together play a crucial role in finding the complete Pareto front for the MONPD. Simulation results illustrate that the reported method, by calculating the complete Pareto front, can provide the best support to decision makers in the MONPD
Early detection of ripple propagation in evolving software systems
No full textRipple effect analysis is the analysis of the consequential knock on effects of a change to a software system. In the first part of this study, ripple effect analysis methods are classified into several categories based on the types of information the methods analyse and produce. A comparative and analytical study of methods from these categories was performed in an attempt to assist maintainers in the selection of ripple effect analysis methods for use in different phases of the software maintenance process. It was observed that existing methods are most usable in the later stages of the software maintenance process and not at an early stage when strategic decisions concerning project scheduling are made. The second part of the work, addresses itself to the problem of tracing the ripple effect of a change, at a stage earlier in the maintenance process than existing ripple effect analysis methods allow. Particular emphasis is placed upon the development of ripple effect analysis methods for analysing system documentation. The ripple effect analysis methods described in this thesis involve manipulating a novel graph theory model called a Ripple Propagation Graph. The model is based on the thematic structure of documentation, previous release information and expert judgement concerning potential ripple effects. In the third part of the study the Ripple Propagation Graph model and the analysis methods are applied and evaluated, using examples of documentation structure and a major case study
Resilience strategies to recover from the cascading ripple effect in a copper supply chain through project management
No full textAs the supply chains are growing and becoming more interdependent, the vulnerability and the chances of supply chain failure also increases. The supply chain industry is severely affected due to the COVID-19 outbreak and industry practitioners are focusing on minimizing the ripple effect of the disruption made to the economy. Considering the unprecedented situation, the research is motivated to analyse the ripple effect in a multi-echelon supply chain and investigate the performance at various nodes to understand the capability of the supply chain to withstand the disruptions at different levels. Using discrete event simulation, this study analyses the ripple effect in the copper industry by an agent-based simulation software anyLogistix, considering various key performance indexes (KPIs) to gauge the magnitude. From the results of the simulation, it is evident that the lack of safety stocks and multi-sourcing of copper facilitate as major causes for the disruptions. The simulation helps to understand the disruption levels and make the supply chain more resilient and robust for any future disruption. Further, the study proposes resilient project management solutions to recover from the cascading ripple effect in the copper supply chain. The scientific contribution of the research is to provide supply chain managers with simulation techniques to understand the ripple effect on the copper supply chain. It helps the stakeholders to understand the importance of project management tools to reduce the cascading ripple effect in a copper supply chain. Further, the findings of this study will support contemporary managers, supply chain allies, project managers, and stakeholders to formulate strategies for recovering from the supply chain disruptions caused due to natural disasters, pandemics such as COVID-19
Core Losses and Torque Ripple in IPM Machines: Dedicated Modeling and Design Trade Off
No full textThe proper combination of stator and rotor slot numbers is pursued in the design of interior permanent-magnet (IPM) motors with wide constant-power speed range. At high speed, in the flux-weakening region, the arising of stator and rotor iron losses due to magnetomotive-force (MMF) spatial harmonics limits the IPM motor performance. Torque ripple is another problem for this kind of machines, both at low and high speed. The numbers of stator slots and rotor equivalent slots have a major impact on both the loss and ripple aspects. A simplified model is proposed here in order to evaluate both problems with a general approach and point out the possible design tradeoff. With respect to previous models in the literature, both stator and rotor losses are included, and a more comprehensive approach is followed in the description of the rotor MMF harmonics. The model's effectiveness is tested through finite element analysis simulations and some experimental results. The proposed approach is useful for the selection of the IPM machine structure according to the specific requirements of the applicatio
Is ripple effect intuitive? A pilot study
No full textThe computation of ripple effect is based on the effect that a change to a single variable will have on the rest of a program; it determines the scope of the change and provides a measure of the program’s complexity. The original algorithm used to compute ripple effect has been reformulated mainly to provide clarity in the operations involved. The reformulation involved some approximation which was shown not to affect the measures produced. The reformulated, approximated algorithm has been implemented as the software tool: Ripple Effect and Stability Tool (REST). This paper uses a software development project as a case study to look at the relationship between the approximated ripple effect and a programmer’s intuitive idea of ripple effect. Four versions of a mutation testing software tool were written in C over a period of several months. After the completion of each version the programmer was asked to detail his predicted/intuitive ripple effect for each module of code. The predictions are compared with the approximated ripple effect measures for each module and some surprising conclusions drawn
Alternative Futures: Who Decides? The honest inclusion of community voices in decision-making
No full textThe following report is a call to action. It describes the outcomes from a research partnership between “The Ripple Project”, a Community Centre serving Restalrig, Lochend and Craigentinny, and the “Binks Hub”, a research group based at the University of Edinburgh.
This collaboration has highlighted both a strong desire for improvements in core areas – such as community and green spaces – and demand from the community that their voices be heard on their own terms. Community members feel excluded from decision-making processes, despite prior engagement attempts from local and national government. They feel that lip service is paid to their local knowledge and lived experience, but they are not able to set the foundational terms on which policies are formed.
Our work shows that different ways of working together are possible: ways that allow community knowledge to be brought to the forefront and which deliver more efficient outcomes that will have a much greater positive impact on the communities being served
The Contribution of Sand Ripple and Slope Driven Sediment Flux to Morphologic Change of an Idealized Mound Under Waves
No full textWe investigate pathways of sediment diffusion for a Gaussian-shaped sand mound subjected to monochromatic waves. Our unique results nearly close the sediment budget by quantifying each of the sediment transport processes responsible for mound diffusion associated with sediment flux due to slope driven transport and ripple migration. Downslope ripple progression was observed as ripples formed at the mound top advanced down the side slopes in a direction perpendicular to wave propagation. Once ripples formed on the sides of the mounds the ripples became pathways for sediment flux from the top to the bottom of the mound, persisting even after ripples reached the base of the mound as sediment avalanching due to gravity and mound slope. Lateral ripple migration caused ripples to migrate along the sides of the sand mound in a direction parallel to wave propagation. Once ripples reached the base of the mound, lateral migration of ripples caused spreading of sand around the sides of the mound. Lateral ripple migration was largely driven by ripple splitting caused by a large downslope sediment flux from the center of the mound that generated ripples with longer wavelengths than wave orbital hydrodynamics could support. To restore equilibrium between sediment and flow conditions, ripples with longer wavelengths continuously split and migrated laterally around the mound. Our results reflect the importance of slope driven transport, bed fluidization, and ripple dynamics on the larger scale diffusivity and suggest that slope driven and ripple driven sediment fluxes should be more explicitly included in sediment transport formulations.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Coastal Engineerin
Alternative Futures: Who Decides? A story of lived experiences told through art
No full textThis mini-book tells the story of the ‘The Ripple – Past, Present, Future’ Project, conducted as a research partnership between the Ripple Project, a community organisation in the Restalrig, Lochend and Craigentinny areas in Northeast Edinburgh, and the Binks Hub (University of Edinburgh) in 2023-24. The project used community art-making, creative and curational methods and practices to co-research local people’s experiences and understandings of their community, and express their hopes, dreams and demands for the future. In this mini-book we focus on the four artworks produced through the project and the series of exhibitions we curated to display them. We discuss how these exhibitions were curated to carry the wisdom of the community to wider audiences, and how this wisdom gives rise to a series of participatory democracy demands made of policymakers. The policy-focused aims of the project are summarised here, but are expanded upon in greater detail in our companion publication Alternative Futures: Who Decides? – The respectful inclusion of community voices in decision-making
Active Ripple Cancellation in Hysteretic Controlled Buck Converters
No full textabstract: Buck converters are a class of switched-mode power converters often used to step down DC input voltages to a lower DC output voltage. These converters naturally produce a current and voltage ripple at their output due to their switching action. Traditional methods of reducing this ripple have involved adding large discrete inductors and capacitors to filter the ripple, but large discrete components cannot be integrated onto chips. As an alternative to using passive filtering components, this project investigates the use of active ripple cancellation to reduce the peak output ripple. Hysteretic controlled buck converters were chosen for their simplicity of design and fast transient response. The proposed cancellation circuits sense the output ripple of the buck converter and inject an equal ripple exactly out of phase with the sensed ripple. Both current-mode and voltage-mode feedback loops are simulated, and the effectiveness of each cancellation circuit is examined. Results show that integrated active ripple cancellation circuits offer a promising substitute for large discrete filters
Predicting wave-induced ripple equilibrium geometry
No full textAuthor Posting. © American Geophysical Union, 2013. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 118 (2013): 3202–3220, doi:10.1002/jgrc.20241.A comprehensive database of existing (since 1954) field and laboratory measurements of ripple geometry is compiled and combined with newly collected field data to examine the performance of ripple equilibrium predictors. Reanalysis of this enlarged ripple geometry data set reveals that ripples formed from monochromatic waves scale differently than ripples formed from random waves for many existing ripple predictors. Our analysis indicates that ripple wavelengths from the two data sets collapse into a single scaling when the semiorbital excursion and sediment grain diameter are used as normalizing factors. Ripple steepness remains relatively constant for both regular and irregular wave conditions, and it only slightly increases for shorter ripple wavelengths. These findings allowed for the development of a new equilibrium ripple predictor suitable for application in a wide range of wave and sediment conditions.Financial support for this work was provided
by the National Science Foundation (NSF awards OCE-0451989 and
OCE-0535893) and by the South Carolina Coastal Erosion Project, a cooperative
study supported by the U.S. Geological Survey and the South Carolina
Sea Grant Consortium (Sea Grant Project R/CP-11).2013-12-2
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