Possible ways to improve the comfort, fit and visual performance of swimming goggles

The primary aim of this thesis was to provide a comprehensive evaluation of the human face so that it can be used to improve the design of swimming goggles with regards to comfort and fit. The secondary aim was concerned with vision and was to identify whether a curved lens could be plausible for use in a performance racing goggle. [Continues.

NASA Tech Briefs, November 2002

Topics include: a technology focus on engineering materials, electronic components and systems, software, mechanics, machinery/automation, manufacturing, bio-medical, physical sciences, information sciences book and reports, and a special section of Photonics Tech Briefs

NASA Tech Briefs, March 1995

This issue contains articles with a special focus on Computer-Aided design and engineering amd a research report on the Ames Research Center. Other subjects in this issue are: Electronic Components and Circuits, Electronic Systems, Physical Sciences, Materials, Computer Programs, Mechanics, Machinery, Manufacturing/Fabrication, Mathematics and Information Sciences and Life Science

NASA Tech Briefs, July 2001

Topics include: special coverage sections on Data Acquisition, and sections on electronic components and systems, software, mechanics, machinery/automation, biomedical and a special section of Photonics Tech Briefs

NASA Tech Briefs, August 1996

Topics covered include: Graphics and Simulation; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery/Automation; Manufacturing/Fabrication; Mathematics and Information Sciences; Life Sciences; Books and Report

A review of gerotor technology in hydraulic machines

Over the years, numerous investigations have established the gerotor fundamentals. This work aims to provide a complete review of the literature from the last decade, focusing on the articles published in the past five years on gerotor technology in hydraulic machines. The report gives a catalogue of guidelines based on the trochoidal-envelope definition, a background analysis, the worldwide distribution of articles in each continent and country and the most frequently used keywords in the field. The paper identifies state-of-the-art research, and reports on current mainstream ideas. From the historical background, this literature review reports the current approaches in gerotor pumps (geometry and performance approaches, modeling and numerical simulations), orbital motors and new concepts. The report will serve as a guide and a directory for novel engineers working with gerotor technology in hydraulic machines. Another intention of this paper is to disseminate the works of the researchers who use this technology around the world, and to provide a scenario for future international collaboration. The paper gives an account of the disparity between academia and engineering applications. There is currently very little published literature on design and production methodologies for gerotor pumps and orbital motors. Hence, the future goal is to collect recommendations that combine academia and industry expertise to make better use of these extensive studies in the fieldPostprint (published version

Model validation and transition to turbulence in orbiting culture dishes.

Wall shear stress (WSS) is commonly accepted as the primary influence affecting characteristics of anchored endothelial cells when subjected to fluid flow. Orbital shakers are commonly used to study cellular responses due to their ease of use, ability to run several experiments simultaneously, and since they exert physiologically relevant oscillatory shear. These studies require comprehensive resolution of WSS, however the fluid dynamics inside orbiting culture dishes has not yet been well described since the flow is complex and difficult to quantify analytically. A computational fluid dynamics (CFD) model of flow in an orbiting dish has been developed that yields detailed spatial and temporal resolution of WSS. The model was initially validated against primitive single point laser Doppler velocimetry data from the literature. A more comprehensive validation of the model was then performed here using both Particle Image Velocimetry (PIV) and a limited analytical solution that neglects wall effects. Average computational normalized velocity magnitudes varied by an average of just 0.3% from experimental PIV and from the analytical solution by 2.4%. WSS contours also compared very well qualitatively. Turbulence intensities were generated from PIV for a wide range of Reynolds numbers, Froude numbers, Stokes numbers, and Slope Ratios in order to determine transition to turbulent flow. Froude number best defined the transition to turbulence with the transition occurring between 0.69 and 0.86. Velocity contours from PIV showed distinct patterns indicating laminar, transitional, and turbulent flow

NASA Tech Briefs, May 2002

Topics include: a technology focus on engineering materials, electronic components and circuits, software, mechanics, machinery/automation, manufacturing, physical sciences, information sciences, book and reports, and a special section of Photonics Tech Briefs

Digital twin—The dream and the reality

Digital twins (DTs) are under active research and development in the research community, industry, and in the digital engineering solution business. The roots of the concept of DT are almost 2 decades old, but the fast progress in enabling technologies, especially in data analytics, artificial intelligence, and the Internet of Things, has accelerated the evolution of DT during the last 5 years. The growing interest, increasing development activities, and increasing business opportunities of the concept are also feeding the hype in the media. Consequently, this has led to the scattering and even misuse of the concept and its definition. In this article, we discuss different applications of DTs and what kinds of solutions there are for DTs. We analyze some most cited definitions of DT in the scientific literature and discuss the interpretation of the definitions through a hypothetical case example. Furthermore, we discuss different life cycle aspects of DTs and potential risks that may arise. To further concretize the concept of DT, we introduce ten reported case examples of implemented DTs in the scientific literature and analyze their features. Finally, we discuss the future development directions of DTs and the aspects that will affect the development trends