Use of Parameter Estimation for Stereolithography Surface Finish Improvement

In order to improve Stereolithography (SLA) surface finish, a systematic approach based on estimation of process parameters is needed. In this paper, the exposure on a desired SLA build surface is formulated as a function of process parameters. The deviation of exposure on this surface from the critical exposure, which is the threshold that determines curing in the SLA process, is formulated using least squares minimization. By applying inverse design techniques, SLA process parameters that satisfy this least squares minimization are determined. Application of parameter estimation formulation to important SLA geometries is presented and the results, including surface finish improvement, are discussed.Mechanical Engineerin

SciTech News Volume 70, No. 4 (2016)

Columns and Reports From the Editor 3 Division News Science-Technology Division 4 SLA Annual Meeting 2016 Report (S. Kirk Cabeen Travel Stipend Award recipient) 6 Reflections on SLA Annual Meeting (Diane K. Foster International Student Travel Award recipient) 8 SLA Annual Meeting Report (Bonnie Hilditch International Librarian Award recipient)10 Chemistry Division 12 Engineering Division 15 Reflections from the 2016 SLA Conference (SPIE Digital Library Student Travel Stipend recipient)15 Fundamentals of Knowledge Management and Knowledge Services (IEEE Continuing Education Stipend recipient) 17 Makerspaces in Libraries: The Big Table, the Art Studio or Something Else? (by Jeremy Cusker) 19 Aerospace Section of the Engineering Division 21 Reviews Sci-Tech Book News Reviews 22 Advertisements IEEE 17 WeBuyBooks.net 2

Learner internal psychological factors

Book synopsis: What is language and how can we investigate its acquisition by children or adults? What perspectives exist from which to view acquisition? What internal constraints and external factors shape acquisition? What are the properties of interlanguage systems? This comprehensive 31-chapter handbook is an authoritative survey of second language acquisition (SLA). Its multi-perspective synopsis on recent developments in SLA research provides significant contributions by established experts and widely recognized younger talent. It covers cutting edge and emerging areas of enquiry not treated elsewhere in a single handbook, including third language acquisition, electronic communication, incomplete first language acquisition, alphabetic literacy and SLA, affect and the brain, discourse and identity. Written to be accessible to newcomers as well as experienced scholars of SLA, the Handbook is organised into six thematic sections, each with an editor-written introduction

Evaluation of Die Trim Morphology Made by CAD-CAM Technology

Statement of problem The die contour can affect the emergence profile of prosthetic restorations. However, little information is available regarding the congruency between a stereolithographic (SLA) die and its corresponding natural tooth. Purpose The purpose of this vitro study was to evaluate the shapes of SLA die in comparison with the subgingival contour of a prepared tooth to be restored with a ceramic crown. Material and methods Twenty extracted human teeth, 10 incisors, and 10 molars, were disinfected and mounted in a typodont model. The teeth were prepared for a ceramic restoration. Definitive impressions were made using an intraoral scanner from which 20 SLA casts with removable dies were fabricated. The removable dies and corresponding human teeth were digitized using a 3-dimensional desktop scanner and evaluated with computer-aided design software. The subgingival morphology with regard to angle, length, and volume at the buccolingual and mesiodistal surfaces and at zones A, B, C, and D were compared. Data were first analyzed with repeated measures analysis of variance (ANOVA), using locations (buccolingual and mesiodistal), zones (A, B, C, and D), and model type (SLA and Natural) as within-subject factors and tooth type (molar and incisor) as the between-subject factor. Post hoc analyses were performed to investigate the difference between natural teeth and corresponding SLA models, depending upon the interaction effect from the repeated measures ANOVA (α=.05). Results For angle analysis, the incisor group demonstrated a significant difference between the natural tooth and SLA die on the buccolingual surfaces (PPPPPP Conclusions For the comparison of angles, SLA dies did not replicate the subgingival contour of natural teeth on the buccolingual surfaces of the incisal groups. For the comparison of length and volume, SLA dies were more concave and did not replicate the subgingival contour of natural teeth in the incisal and molar groups

Automating SLA-Driven API Development with SLA4OAI

The OpenAPI Specification (OAS) is the de facto standard to describe RESTful APIs from a functional perspective. OAS has been a success due to its simple model and the wide ecosystem of tools supporting the SLA-Driven API development lifecycle. Unfortunately, the current OAS scope ignores crucial information for an API such as its Service Level Agreement (SLA). Therefore, in terms of description and management of non-functional information, the disadvantages of not having a standard include the vendor lock-in and prevent the ecosystem to grow and handle extra functional aspects. In this paper, we present SLA4OAI, pioneering in extending OAS not only allowing the specification of SLAs, but also supporting some stages of the SLA-Driven API lifecycle with an open-source ecosystem. Finally, we validate our proposal having modeled 5488 limitations in 148 plans of 35 real-world APIs and show an initial interest from the industry with 600 and 1900 downloads and installs of the SLA Instrumentation Library and the SLA Engine.Ministerio de Economía y Competitividad TIN2015-70560-RMinisterio de Ciencia, Innovación y Universidades RTI2018-101204-B-C21Ministerio de Educación, Cultura y Deporte FPU15/0298

The Statistical Loop Analyzer (SLA)

The statistical loop analyzer (SLA) is designed to automatically measure the acquisition, tracking and frequency stability performance characteristics of symbol synchronizers, code synchronizers, carrier tracking loops, and coherent transponders. Automated phase lock and system level tests can also be made using the SLA. Standard baseband, carrier and spread spectrum modulation techniques can be accomodated. Through the SLA's phase error jitter and cycle slip measurements the acquisition and tracking thresholds of the unit under test are determined; any false phase and frequency lock events are statistically analyzed and reported in the SLA output in probabilistic terms. Automated signal drop out tests can be performed in order to trouble shoot algorithms and evaluate the reacquisition statistics of the unit under test. Cycle slip rates and cycle slip probabilities can be measured using the SLA. These measurements, combined with bit error probability measurements, are all that are needed to fully characterize the acquisition and tracking performance of a digital communication system

On the Use of Angled, Dynamic Laser Beams to Improve Stereolithography Surface Finish

Improved surface finish of Stereolithography (SLA) parts is an important goal for furthering the resolution of the technology. In order to improve the surface finish, a dynamic laser beam with changing angle, beam size, beam shape, and irradiance distribution is proposed. In this paper, an analytical irradiance model of an angled, dynamic laser beam in the SLA process is presented. This model is used to simulate cured shapes of SLA builds. Simulated build shapes are compared to established SLA analytical models and conclusions are drawn on the accuracy of the developed model.Mechanical Engineerin

The Sustainable Livelihoods Approach as an impact assessment tool for development interventions in rural Tigray, Ethiopia : opportunities & challenges

Measuring the impact and sustainability of development programmes requires the development of appropriate assessment tools. This paper examines the Sustainable Livelihoods Approach's (SLA) potential to be transformed to and called in as a practical instrument to evaluate the impact of development interventions in rural Tigray (Northern Ethiopia). Fieldwork has been carried out in communities in woreda Dogua Tembien using participant observation and open interviews as methods. Next to more general challenges of defining, measuring and comparing livelihood assets, context specific factors complicate the operationalisation of the SLA as an impact assessment tool in the area. The SLA distinguishes between livelihood assets on the one hand and transforming structures and processes on the other. The latter lend meaning and value to the former. This conceptual distinction is worthy as it makes the two-way interaction between both categories explicit and escapes from reducing institutions, organisations, policies and legislation to context or background. However, in practice the boundaries are fuzzy and not easy to interpret. The example of religion as a cross-cutting organizing principle illustrates this assumption. Moreover the distinction complicates the operationalisation of the SLA as it implies the meaning and value of capitals to be volatile and depending on the prevailing social, institutional and organisational environment. This is exemplified with the big transforming power of policy shifts in the area. For the SLA to serve as an impact assessment tool, it requires a culture- and policy-sensitive analysis of farmers' asset base. Only a sound understanding of the interactions between livelihood assets and transforming structures and processes can lead to a locally contextualised, meaningful and workable impact assessment tool that measures asset levels using indicators that reflect farmers' own criteria to judge development interventions

Fostering SLA-Driven API Specifications

Software architecture tendencies are shifting to a microservice paradigm. In this context, RESTful APIs are being established the standard of integration. API designer often identifies two key issues to be competitive in such growing market. On the one hand, the generation of accurate documentation of the behavior and capabilities of the API to promote its usage; on the other hand, the design of a pricing plan that fits into the potential API user’s needs. Besides the increasing number of API modeling alternatives is emerging, there is a lack of proposals on the definition of flexible pricing plans usually contained in the Service Level Agreements (SLAs). In this paper we propose two different modeling techniques for the description of SLA in a RESTful API context: iAgree and SLA4OAI.Ministerio de Economía y Competitividad TIN2015-70560-RJunta de Andalucía P12-TIC-1867Ministerio de Economía y Competitividad TIN2014-53986-RED