Advanced design optimization of cold-formed steel portal frame buildings

The design optimization of cold-formed steel portal frame buildings is considered in this paper. The objective function is based on the cost of the members for the main frame and secondary members (i.e., purlins, girts, and cladding for walls and roofs) per unit area on the plan of the building. A real-coded niching genetic algorithm is used to minimize the cost of the frame and secondary members that are designed on the basis of ultimate limit state. It iis shown that the proposed algorithm shows effective and robust capacity in generating the optimal solution, owing to the population's diversity being maintained by applying the niching method. In the optimal design, the cost of purlins and side rails are shown to account for 25% of the total cost; the main frame members account for 27% of the total cost, claddings for the walls and roofs accounted for 27% of the total cost.

Design characteristic of randomised controlled trials for geographic atrophy in age-related macular degeneration: selection of outcomes and sample size calculation

PurposeThe selection of suitable outcomes and sample size calculation are critical factors in the design of a randomised controlled trial (RCT). The goal of this study was to identify the range of outcomes and information on sample size calculation in RCTs on geographic atrophy (GA).MethodsWe carried out a systematic review of age-related macular degeneration (AMD) RCTs. We searched MEDLINE, EMBASE, Scopus, Cochrane Library, www.controlled-trials.com, and www.ClinicalTrials.gov. Two independent reviewers screened records. One reviewer collected data and the second reviewer appraised 10% of collected data. We scanned references lists of selected papers to include other relevant RCTs.ResultsLiterature and registry search identified 3816 abstracts of journal articles and 493 records from trial registries. From a total of 177 RCTs on all types of AMD, 23 RCTs on GA were included. Eighty-one clinical outcomes were identified. Visual acuity (VA) was the most frequently used outcome, presented in 18 out of 23 RCTs and followed by the measures of lesion area. For sample size analysis, 8 GA RCTs were included. None of them provided sufficient Information on sample size calculations.ConclusionsThis systematic review illustrates a lack of standardisation in terms of outcome reporting in GA trials and issues regarding sample size calculation. These limitations significantly hamper attempts to compare outcomes across studies and also perform meta-analyses.

A design strategy of large grain lithium-rich layered oxides for lithium-ion batteries cathode

Li-rich materials are considered the most promising for Li-ion battery cathodes, as high capacity can be achieved. However, poor cycling stability is a critical drawback that leads to poor capacity retention. Here a strategy is used to synthesize a large-grain lithium-rich layered oxides to overcome this difficulty without sacrificing rate capability. This material is designed with micron scale grain with a width of about 300 nm and length of 1-3 μm. This unique structure has a better ability to overcome stress-induced structural collapse caused by Li-ion insertion/extraction and reduce the dissolution of Mn ions, which enable a reversible and stable capacity. As a result, this cathode material delivered a highest discharge capacity of around 308 mAh g^-1 at a current density of 30 mA g^-1 with retention of 88.3% (according to the highest discharge capacity) after 100 cycles, 190 mAh g^-1 at a current density of 300 mA g^-1 and almost no capacity fading after 100 cycles. Therefore, Lithium-rich material of large-grain structure is a promising cathode candidate in Lithium-ion batteries with high capacity and high cycle stability for application. This strategy of large grain may furthermore open the door to synthesize the other complex architectures for various applications.

Piñatex, the design development of a new sustainable material

This is a research project by practice, which firstly develops a new material invention derived from natural fibres extracted from waste pineapple leaves; secondly it articulates the contemporary designer’s role in facilitating sustainable solutions through: Insights from my own material invention, PiñatexTM, which integrates the materiality of design with the immateriality of concepts and values Developing a visual model of mapping I began with these questions: ‘What are the challenges in seeking to make a new and sustainable material from the waste products of pineapple agriculture in the Philippines?’ and ‘How can a design practice link elements of materiality (artifacts) with immaterial elements (value systems) in order to improve sustainable social and economic development?’ Significant influences have been the work of Papanek1 (2003), Hawken2 (1999) and Abouleish3 (2008) and in particular the ethical business model initiated by McDonough and Braungart in Cradle to Cradle®4 (2002). My own research project is inspired by the Cradle to Cradle® model. It proposes the development of a new material, PiñatexTM which is derived from natural fibres extracted from waste pineapple leaves and could be used in a wide variety of products that are currently fabricated in leather or petroleum-based materials. The methods have comprised: Contextual reviews; case studies (SEKEM, Cradle to Cradle® and Gawad Kalinga); practical experiments in the field of natural fibres, chemistry, product development, manufacturing and prototyping, leading to an invention and a theoretical model of mapping. In addition, collaboration has taken place across scientific, technological, social, ecological, academic and business fields. The outcome is a new material based on the synchronicity between the pineapple fibres, polymers, resins and coatings specially formulated. The invention of the new material that I developed as a central part of this research by practice has a patent in the national phase (PCT/GB 2011/000802) and is in the first stages of manufacturing, commercial testing and further design input (Summer 2014). The contribution to knowledge is firstly the material, PiñatexTM, which exhibits certain key qualities, namely environmentally non-toxic, biodegradable, income-generating potential and marketability. This is alongside its intrinsic qualities as a textile product: aesthetic potential, durability and stability, which will make it suitable for the accessories, interiors and furnishing markets. The theoretical mapping system Upstream and Downstream forms a secondary contribution.

Conceptions of subject analysis: a metatheoretical investigation

Thesis (Ph. D.)--University of Washington, 2005.

Mix design process of polyester polymer mortars modified with recycled GFRP waste materials

In this study, the effect of incorporation of recycled glass fibre reinforced plastics (GFRP) waste materials, obtained by means of shredding and milling processes, on mechanical behaviour of polyester polymer mortars (PM) was assessed. For this purpose, different contents of GFRP recyclates, between 4% up to 12% in weight, were incorporated into polyester PM materials as sand aggregates and filler replacements. The effect of the addition of a silane coupling agent to resin binder was also evaluated. Applied waste material was proceeding from the shredding of the leftovers resultant from the cutting and assembly processes of GFRP pultrusion profiles. Currently, these leftovers as well as non-conform products and scrap resulting from pultrusion manufacturing process are landfilled, with additional costs to producers and suppliers. Hence, besides the evident environmental benefits, a viable and feasible solution for these wastes would also conduct to significant economic advantages. Design of experiments and data treatment were accomplish by means of full factorial design approach and analysis of variance ANOVA. Experimental results were promising toward the recyclability of GFRP waste materials as partial replacement of aggregates and reinforcement for PM materials, with significant improvements on mechanical properties of resultant mortars with regards to waste-free formulations.

An approach for reliability-based robust design optimisation of angle-ply composites

Variations of manufacturing process parameters and environmental aspects may affect the quality and performance of composite materials, which consequently affects their structural behaviour. Reliability-based design optimisation (RBDO) and robust design optimisation (RDO) searches for safe structural systems with minimal variability of response when subjected to uncertainties in material design parameters. An approach that simultaneously considers reliability and robustness is proposed in this paper. Depending on a given reliability index imposed on composite structures, a trade-off is established between the performance targets and robustness. Robustness is expressed in terms of the coefficient of variation of the constrained structural response weighted by its nominal value. The Pareto normed front is built and the nearest point to the origin is estimated as the best solution of the bi-objective optimisation problem.

Design of experiments applied to the mix design process of polymer mortar materials modified with GFRP recyclates

In this work, the effect of incorporation of recycled glass fibre reinforced plastics (GFRP) waste materials, obtained by means of shredding and milling processes, on mechanical behavior of polyester polymer mortar (PM) materials was assessed. For this purpose, different contents of GFRP recyclates (between 4% up to 12% in mass), were incorporated into polyester PM materials as sand aggregates and filler replacements. The effect of silane coupling agent addition to resin binder was also evaluated. Applied waste material was proceeding from the shredding of the leftovers resultant from the cutting and assembly processes of GFRP pultrusion profiles. Currently, these leftovers, jointly with unfinished products and scrap resulting from pultrusion manufacturing process, are landfilled, with supplementary added costs. Thus, besides the evident environmental benefits, a viable and feasible solution for these wastes would also conduct to significant economic advantages. Design of experiments and data treatment were accomplish by means of full factorial design approach and analysis of variance ANOVA. Experimental results were promising toward the recyclability of GFRP waste materials as aggregates and reinforcement for PM materials, with significant improvements on mechanical properties with regard to non-modified formulations.

Show me, help me, let me : supporting teachers' changing conceptions of reading assessment and reading instruction

This qualitative inquiry used case study methodology to explore the change processes of 3 primary-grade teachers throughout their participation in 7 -month professional learning initiative focused on reading assessment and instruction. Participants took part in semimonthly inquiry-based professional learning community sessions, as well as concurrent individualized classroom-based literacy coaching. Each participant's experiences were first analyzed as a single case study, followed by cross-case analyses. While their patterns of professional growth differed, findings documented how all participants altered their understandings of the roles and relevancy of individual components of reading instruction (e.g., comprehension, decoding) and instructional approaches to scaffold students' growth (e.g., levelled text, strategy instruction), and experienced some form of conceptual change. Factors identified as affecting their change processes included; motivation, professional knowledge, professional beliefs (self-efficacy and theoretical orientation), resources (e.g., time, support), differentiated professional learning with associated goal-setting, and uncontrollable influences, with the affect of each factor compounded by interaction with the others. Comparison of participants' experiences to the Cognitive-Affective Model of Conceptual Change (CAMCC) and the Interconnected Model of Teacher Professional Growth (IMTPG) demonstrated the applicability of using both conceptual models, with the IMTPG providing macrolevel insights over time and the CAMCC microlevel insights at each change intervaL Recommendations include the provision of differentiated teacher professional learning opportunities, as well as research documenting the effects of teacher mentorship programs and the professional growth of teacher educators. ii

Conceptions of Quality and Approaches to Quality Assurance in Ontario’s Universities

Many international, political, and economic influences led to increased demands for development of new quality assurance systems for universities. Like many policies and processes that aim to assure quality, Ontario’s Quality Assurance Framework (QAF) did not define quality. This study sought to explore conceptions of quality and approaches to quality assurance used within Ontario’s universities. A document analysis of the QAF’s rationale and structure suggested that quality was conceived primarily as fitness for purpose, while suggested indicators represented an exceptional conception of quality. Ontario universities perpetuated such confusion by adopting the framework without customizing it to their institutional conceptions of quality. Drawing upon phenomenographic traditions, a qualitative investigation was conducted to better understand various conceptions of quality held by university administrators and to appreciate ways in which they implemented the QAF. Three main approaches to quality assurance were identified: (a) Defending Quality, characterized by conceptions of quality as exceptional, which focuses on administrative accountability and uses a hands-off strategy to defend traditional notions of quality inputs and resources; (b) Demonstrating Quality, characterized by conceptions of quality as fitness for purpose and value for money, which focuses on accountability to students and uses centralized engaged strategies to demonstrate how programs meet current priorities and intended outcomes; and (c) Enhancing Quality, characterized by conceptions of quality as transformation, which focuses on reflection and learning experience and uses engaged strategies to find new ways of improving learning and teaching. The development of a campus culture that values the institution’s function in student learning and quality teaching would benefit from Enhancing Quality approaches to quality assurance. This would require holistic consideration of the beliefs held by members of the institution, a clear articulation of the institution’s conceptions of quality, and a critical analysis of how these conceptions align with institutional practices and policies.

Conceptions of God and narratives of modernity : a hermeneutical interpretation of Charles Taylor's A Secular Age

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Design Considerations of Sonar Projector Arrays with Improved Performance

Systems which employ underwater acoustic energy for observation or communication are called sonar systems. The active and passive sonars are the two types of systems used for the detection and localisation of targets in underwater. Active sonar involves the transmission of an acoustic signal which, when reflected from a target, provides the sonar receiver with a basis for the detection and estimation. Passive sonar bases its detection and estimation on sounds which emanate from the target itself--Machinery noise, flow noise, transmission from its own active sonar etc.Electroacoustic transducers are used in sonar systems for the transmission and detection of acoustic energy. The transducer which is used for the transmission of acoustic energy is called projector and the one used for reception is called hydrophone. Since a single transducer is not sufficient enough for long range and directional transmission, a properly distributed array of transducers are to be used [9-11].The need and requirement for spatial processing to generate the most favourable directivity patterns for transducer systems used in underwater applications have already been analysed by several investigators [12-21].The desired directivity pattern can be either generated by the use of suitable focussing techniques or by an array of non-directional sensor elements, whose arrangements, spacing and the mode of excitation provide the required radiation pattern or by the combination of these.While computing that the directivity pattern, it is assumed strength of the elements are unaffected by the the source acoustic pressure at each source. However, in closely packed a r r a y s , the acoustic interaction effects experienced among the elements will modify the behaviour of individual elements and in turn will reduce the acoust ic source leve 1 wi t h respect to the maximum t heoret i cal va 1ue a s well as degrade the beam pa t tern. Th i s ef fect shou 1d be reduced in systems that are intended to generate high acoustic power output and unperturbed beam patterns [2,22-31].The work herein presented includes an approach for designing efficient and well behaved underwater transd~cer arrays, taking into account the acoustic interaction effect experienced among the closely packed multielement arrays.Architectural modifications reducing the interaction effect different radiating apertures.