NASA SBIR abstracts of 1991 phase 1 projects

The objectives of 301 projects placed under contract by the Small Business Innovation Research (SBIR) program of the National Aeronautics and Space Administration (NASA) are described. These projects were selected competitively from among proposals submitted to NASA in response to the 1991 SBIR Program Solicitation. The basic document consists of edited, non-proprietary abstracts of the winning proposals submitted by small businesses. The abstracts are presented under the 15 technical topics within which Phase 1 proposals were solicited. Each project was assigned a sequential identifying number from 001 to 301, in order of its appearance in the body of the report. Appendixes to provide additional information about the SBIR program and permit cross-reference of the 1991 Phase 1 projects by company name, location by state, principal investigator, NASA Field Center responsible for management of each project, and NASA contract number are included

Temperature and heat flux measurements: Challenges for high temperature aerospace application

The measurement of high temperatures and the influence of heat transfer data is not strictly a problem of either the high temperatures involved or the level of the heating rates to be measured at those high temperatures. It is a problem of duration during which measurements are made and the nature of the materials in which the measurements are made. Thermal measurement techniques for each application must respect and work with the unique features of that application. Six challenges in the development of measurement technology are discussed: (1) to capture the character and localized peak values within highly nonuniform heating regions; (2) to manage large volumes of thermal instrumentation in order to efficiently derive critical information; (3) to accommodate thermal sensors into practical flight structures; (4) to broaden the capabilities of thermal survey techniques to replace discrete gages in flight and on the ground; (5) to provide supporting instrumentation conduits which connect the measurement points to the thermally controlled data acquisition system; and (6) to develop a class of 'vehicle tending' thermal sensors to assure the integrity of flight vehicles in an efficient manner

Roadmap on semiconductor-cell biointerfaces.

This roadmap outlines the role semiconductor-based materials play in understanding the complex biophysical dynamics at multiple length scales, as well as the design and implementation of next-generation electronic, optoelectronic, and mechanical devices for biointerfaces. The roadmap emphasizes the advantages of semiconductor building blocks in interfacing, monitoring, and manipulating the activity of biological components, and discusses the possibility of using active semiconductor-cell interfaces for discovering new signaling processes in the biological world

Development, Characterization, & Implementation of Phase-Change Material Cold Plates for Hybrid-Electric Vehicle Battery Systems

Due to the regulations on internal combustion engine vehicles, there is a large demand of hybrid and electric vehicles with large battery packs as Energy Storage Systems (ESS) capable of long ranges and decreased emissions. These battery packs output large heat loads during charge-depletion mode and currently require active cooling to keep the batteries within operating conditions. The current systems relied onto achieve this are the air and liquid cooled thermal managements systems. A recent alternative approach to current cooling for ESS thermal management is the use of phase-change materials (PCMs). PCMs regulate the temperature of the ESS by leveraging the latent heat of fusion to absorb large amounts of energy at constant temperature while changing phase from solid to liquid. While PCMs have large heat capacities, the downside is their low thermal conductivity which causes them to melt unevenly, which is a main reason PCM is not ideal for cooling systems. The study will involve fully investigating the use of PCM into a hybrid-electric vehicle battery thermal management system. The proposed methodology is to mix thermal conductivity enhancing material, loose carbon fibers, into the PCM to spread the heat absorbed more evenly throughout the entire mass. This material matrix is characterized in order to determine the necessary material and thermal properties to justify its use and implantation in the EcoEagles 2016 Chevrolet Camaro for vehicle testing and validations. Results obtained during multiple vehicle tests have demonstrated that the PCM has successfully kept the battery pack at a safe operating condition of under 45◦C. This was done passively resulting in a reduced overall vehicle energy consumption and increased vehicle battery pack efficiency. The study continues by investigating the use of a shape-stabilized phase-change material cold plate that is capable of addressing several issues that a represent with the bulk PCM plate in its current state on the vehicle

Experimental and computational studies of poly-L-lactic acid for cardiovascular applications: recent progress

Stents are commonly used in medical procedures to alleviate the symptoms of coronary heart disease, a prevalent modern society disease. These structures are employed to maintain vessel patency and restore blood flow. Traditionally stents are made of metals such as stainless steel or cobalt chromium; however, these scaffolds have known disadvantages. An emergence of transient scaffolds is gaining popularity, with the structure engaged for a required period whilst healing of the diseased arterial wall occurs. Polymers dominate a medical device sector, with incorporation in sutures, scaffolds and screws. Thanks to their good mechanical and biological properties and their ability to degrade naturally. Polylactic acid is an extremely versatile polymer, with its properties easily tailored to applications. Its dominance in the stenting field increases continually, with the first polymer scaffold gaining FDA approval in 2016. Still some challenges with PLLA bioresorbable materials remain, especially with regard to understanding their mechanical response, assessment of its changes with degradation and comparison of their performance with that of metallic drug-eluting stent. Currently, there is still a lack of works on evaluating both the pre-degradation properties and degradation performance of these scaffolds. Additionally, there are no established material models incorporating non-linear viscoelastic behaviour of PLLA and its evolution with in-service degradation. Assessing these features through experimental analysis accompanied by analytical and numerical studies will provide powerful tools for design and optimisation of these structures endorsing their broader use in stenting. This overview assesses the recent studies investigating mechanical and computational performance of poly(l-lactic) acid and its use in stenting applications

Interactive 3D simulation for fluid–structure interactions using dual coupled GPUs

The scope of this work involves the integration of high-speed parallel computation with interactive, 3D visualization of the lattice-Boltzmann-based immersed boundary method for fluid–structure interaction. An NVIDIA Tesla K40c is used for the computations, while an NVIDIA Quadro K5000 is used for 3D vector field visualization. The simulation can be paused at any time step so that the vector field can be explored. The density and placement of streamlines and glyphs are adjustable by the user, while panning and zooming is controlled by the mouse. The simulation can then be resumed. Unlike most scientific applications in computational fluid dynamics where visualization is performed after the computations, our software allows for real-time visualizations of the flow fields while the computations take place. To the best of our knowledge, such a tool on GPUs for FSI does not exist. Our software can facilitate debugging, enable observation of detailed local fields of flow and deformation while computing, and expedite identification of ‘correct’ parameter combinations in parametric studies for new phenomenon. Therefore, our software is expected to shorten the ‘time to solution’ process and expedite the scientific discoveries via scientific computing

NUMERICAL ANALYSIS OF THE EXTRUSION OF FIBER OPTIC AND PHOTONIC CRYSTAL FIBER PREFORMS NEAR THE GLASS TRANSITION TEMPERATURE

Conventional clad core fiber optic technology has relied on a concentric structure of glass of different refraction indices. These conventional fibers suffer from constraints and limitations related to thermal expansion compatibility between the core and the glass. The new fiber technology broadly characterized as Microstructured Optic Fibers (MOFs) is intended to lift the limitations of conventional clad core fibers and also extend the range of application of fiber optics. Photonic Cristal Fibers(PCFs) are a special family of Microstructured Optic Fibers characterized by the presence of holes in the cross section of the fiber that are organized in a hexagonal pattern. In order to manufacture these fibers, a preform with the same cross section has to be prepared which can later be drawn into fiber. For such complex geometry, glass extrusion at a viscosity higher than that for extrusion of solid glass preforms has proven to give better results. Despite these merits, the numerical modeling of the extrusion of glass at high viscosity has not received much attention in the literature. Thus, in order to study the extrusion of PCF performs at high viscosity, investigation of the extrusion of a solid glass preform must be considered first. To establish the valid assumptions to model glass extrusion at high viscosity, a numerical study of solid rod extrusion was performed and validated based on five experimental cases. This study highlighted the importance of including friction effects to validate both the value of ram force and die swell. Since the Navier law is the most widely used friction law in the extrusion literature and has been identified as a key parameter required in modeling, the ring compression test was adapted to obtain the Navier friction coefficient from standard ring compression test data. In addition to the identification of the essential modeling choices base on experimental data, a sensitivity analysis was performed on extrusion parameters for both viscous and viscoelastic material to establish a general idea of the effect and relationships that governs the extrusion process. The results from this study correlate with several experimental observations. Based on the same assumptions that were validated for solid rod extrusion, the numerical modeling of extrusion of PCF preforms was performed using two Blockage geometries. The model was validated for both Blockages qualitatively based on a preform showing a significantly deformed cross section. To investigate the creation and the distortion of the holes of PCF preforms, a sensitivity analysis was also performed using both Blockages. To quantify and interpret the distortion data the implementation of several algorithms and mathematical methods were developed. In addition, other tools were developed to provide a way to alter the Blockage geometry in order to improve the geometric quality of the preform. An example of this alteration was carried out

Vortex Spinning System and Vortex Yarn Structure

Studying the yarn formation with the swirling air concept arouse of interest of the researchers for a long time because it appears to be easy to understand as a spinning principle. These kinds of systems are known as the vortex yarn spinning systems. The air-jet spinning methods have been developed since it is possible to eliminate the movable elements as the spindle and the traveler in ring spinning or the centrifuge in rotor spinning. The success of Murata vortex spinning (MVS) system which is the newest system after all studies of air-jet systems has been much acceptable especially for the spinning ability of 100% cotton in high speeds (500 m/min) and the yarn structure resembling ring yarn structure rather than rotor yarns. This study summarizes the historical background of vortex spinning, the spinning principle and the structure of the yarn spun on this system, as well as the factors influencing the yarn quality and finally the developments in vortex spinning technology

Numerical modelling of additive manufacturing process for stainless steel tension testing samples

Nowadays additive manufacturing (AM) technologies including 3D printing grow rapidly and they are expected to replace conventional subtractive manufacturing technologies to some extents. During a selective laser melting (SLM) process as one of popular AM technologies for metals, large amount of heats is required to melt metal powders, and this leads to distortions and/or shrinkages of additively manufactured parts. It is useful to predict the 3D printed parts to control unwanted distortions and shrinkages before their 3D printing. This study develops a two-phase numerical modelling and simulation process of AM process for 17-4PH stainless steel and it considers the importance of post-processing and the need for calibration to achieve a high-quality printing at the end. By using this proposed AM modelling and simulation process, optimal process parameters, material properties, and topology can be obtained to ensure a part 3D printed successfully