44 research outputs found

    Evolvable hardware for space applications

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    Exploiting development to enhance the scalability of hardware evolution.

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    Evolutionary algorithms do not scale well to the large, complex circuit design problems typical of the real world. Although techniques based on traditional design decomposition have been proposed to enhance hardware evolution's scalability, they often rely on traditional domain knowledge that may not be appropriate for evolutionary search and might limit evolution's opportunity to innovate. It has been proposed that reliance on such knowledge can be avoided by introducing a model of biological development to the evolutionary algorithm, but this approach has not yet achieved its potential. Prior demonstrations of how development can enhance scalability used toy problems that are not indicative of evolving hardware. Prior attempts to apply development to hardware evolution have rarely been successful and have never explored its effect on scalability in detail. This thesis demonstrates that development can enhance scalability in hardware evolution, primarily through a statistical comparison of hardware evolution's performance with and without development using circuit design problems of various sizes. This is reinforced by proposing and demonstrating three key mechanisms that development uses to enhance scalability: the creation of modules, the reuse of modules, and the discovery of design abstractions. The thesis includes several minor contributions: hardware is evolved using a common reconfigurable architecture at a lower level of abstraction than reported elsewhere. It is shown that this can allow evolution to exploit the architecture more efficiently and perhaps search more effectively. Also the benefits of several features of developmental models are explored through the biases they impose on the evolutionary search. Features that are explored include the type of environmental context development uses and the constraints on symmetry and information transmission they impose, genetic operators that may improve the robustness of gene networks, and how development is mapped to hardware. Also performance is compared against contemporary developmental models

    Development of a Wearable Mechatronic Elbow Brace for Postoperative Motion Rehabilitation

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    This thesis describes the development of a wearable mechatronic brace for upper limb rehabilitation that can be used at any stage of motion training after surgical reconstruction of brachial plexus nerves. The results of the mechanical design and the work completed towards finding the best torque transmission system are presented herein. As part of this mechatronic system, a customized control system was designed, tested and modified. The control strategy was improved by replacing a PID controller with a cascade controller. Although the experiments have shown that the proposed device can be successfully used for muscle training, further assessment of the device, with the help of data from the patients with brachial plexus injury (BPI), is required to improve the control strategy. Unique features of this device include the combination of adjustability and modularity, as well as the passive adjustment required to compensate for the carrying angle

    Biomimetic Based Applications

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    The interaction between cells, tissues and biomaterial surfaces are the highlights of the book "Biomimetic Based Applications". In this regard the effect of nanostructures and nanotopographies and their effect on the development of a new generation of biomaterials including advanced multifunctional scaffolds for tissue engineering are discussed. The 2 volumes contain articles that cover a wide spectrum of subject matter such as different aspects of the development of scaffolds and coatings with enhanced performance and bioactivity, including investigations of material surface-cell interactions

    Development of a design feature database to support design for additive manufacturing (DfAM)

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    This research introduces a method to aid the design of products or parts to be made using Additive Manufacturing (AM), particularly the laser sintering (LS) system. The research began with a literature review that encompassed the subjects of design and AM and through this the need for an assistive design approach for AM was identified. Undertaking the literature review also confirmed that little has been done in the area of supporting the design of AM parts or products. Preliminary investigations were conducted to identify the design factors to consider for AM. Two preliminary investigations were conducted, the first investigation was conducted to identify the reasons for designing for AM, the need for a design support tool for AM and current challenges of student industrial designers designing parts or products for AM, and also to identify the type of design support they required. Further investigation were conducted to examine how AM products are developed by professional industrial designers and to understand their design processes and procedures. The study has identified specific AM enabled design features that the designers have been able to create within their case study products. Detailed observation of the case study products and parts reveals a number of features that are only economical or possible to produce with AM. A taxonomy of AM enabled design features was developed as a precursor for the development of a computer based design tool. The AM enabled design features was defined as a features that would be uneconomical or very expensive to be produced with conventional methods. The taxonomy has four top-level taxons based on four main reasons for using AM, namely user fit requirements, improved product functionality requirements, parts consolidation requirements and improvement of aesthetics or form requirements. Each of these requirements was expanded further into thirteen sub categories of applications that contained 106 examples of design features that are only possible to manufacture using AM technology. The collected and grouped design features were presented in a form of a database as a method to aid product design of parts or products for AM. A series of user trials were conducted that showed the database enabled industrial designers to visualise and gather design feature information that could be incorporated into their own design work. Finally, conclusions are drawn and suggestions for future work are listed. In summary, it can be concluded that this research project has been a success, having addressed all of the objectives that were identified at its outset. From the user trial results, it is clear to see that the proposed tool would be an effective tool to support product design for AM, particularly from an educational perspective. The tool was found to be beneficial to student designers to take advantage of the design freedom offered by AM in order to produce improved product design. As AM becomes more widely used, it is anticipated that new design features will emerge that could be included in future versions of the database so that it will remain a rich source of inspirational information for tomorrow s industrial designers

    Reports to the President

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    A compilation of annual reports for the 1989-1990 academic year, including a report from the President of the Massachusetts Institute of Technology, as well as reports from the academic and administrative units of the Institute. The reports outline the year's goals, accomplishments, honors and awards, and future plans

    IDENTIFYING AN OPTIMIZATION TECHNIQUE FOR MAKER USAGE TO ADDRESS COVID-19 SUPPLY SHORTFALLS

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    Fused Deposition Modeling (FDM) can be purchased for under five hundred dollars. The availability of these inexpensive systems has created a large hobbyist (or maker) community. For makers, FDM printing is used numerous uses. With the onset of the COVID-19 pandemic, the needs for Personal Protective Equipment (PPE) skyrocketed. COVID-19 mitigation strategies such as social distancing, businesses closures, and shipping delays created significant supply shortfalls. The maker community stepped in to fill gaps in PPE supplies. In the case of 3DP, optimization remains the domain of commercial entities. Optimization is, at best, ad-hoc for makers. With the need to PPE supplies and COVID-19 related supply delays, optimization techniques would be of great value to makers. The objective functions in this research is throughput and cost with quality factored into both. There are several parameters common to both throughput and surface roughness, including layer thickness, print speed, infill density, raster width, and wall thickness. This research will utilize a 2-level fractional factorial design, in which process parameter had a specified upper (+1) and lower (-1) level. By using the upper and lower limits, this study will more closely align with the common maker workflow. The design will have a total of 16 trials, no main effect or 2-factor interactions are confounded with any other main effect or 2-factor interactions, this will allow the parameters to be estimated separately from one another without the requirement for conducting a full factorial (32 trials). Least Squares Regression (OLS) will be completed on throughput and cost independently. Quality will be considered a component of both. For example, an OLS will be completed for the throughput to determine the respective effects of the process parameters on throughput. Using a 95% confidence interval, a process parameter with a P-value smaller that .05 will show that the process parameter has a significant effect on the throughput. Upon completion of each OLS model -Contraint methodology will be used to jointly optimize the process parameters. Validation trials will be completed to test the optimized process parameters. The results will be documented and discussed

    \u3ci\u3eProceedings of the 3rd Scorpiology Symposium\u3c/i\u3e (American Arachnological Society, 28th Annual Meeting)

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    Table of Contents Victor Fet and Douglas D. Gaffin. Preface p. iKaren C. Bost and Douglas D. Gaffin. Sand scorpion home burrow navigation in the laboratory p. 1Douglas D. Gaffin and Mark E. Walvoord. Scorpion peg sensilla: are they the same or are they different? p. 7J. Zachary Porterfield, Douglas D. Gaffin, Caitlin Porterfield and Curtis Johnston. Screening for scorpions: A non-invasive approach to tracking the movements of arachnids in sand p. 17Tsunemi Yamashita. Surface activity, biomass, and phenology of the striped scorpion, Centruroides vittatus (Scorpiones: Buthidae) in Arkansas, USA p. 25C. Neal McReynolds. Temporal patterns in microhabitat use for the scorpion Centruroides vittatus (Scorpiones: Buthidae) p. 35Victor Fet, Michael E. Soleglad and Benjamin Gantenbein. The Euroscorpion: Taxonomy and systematics of the genus Euscorpius Thorell, 1876 (Scorpiones: Euscorpiidae) p.47Victor Fet, Michael E. Soleglad and Alexander Gromov. The platypus of a scorpion: the genus Pseudochactas Thorell, 1876 (Scorpiones: Pseudochactidae) p. 6

    Playful User Interfaces:Interfaces that Invite Social and Physical Interaction

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