163 research outputs found
The impact of lease accounting standards on airlines with operating leases: Implications for benchmarking and financial analysis
In 2016, the Financial Accounting Standards Board (FASB) has issued a new standard for lease accounting. The standard requires capitalization by lessees of most leases currently treated as rentals, i.e., those currently classified as operating leases under the existing standard for lease accounting. We examine the impact on airlines that currently make use of operating leases. Several key financial ratios are examined before capitalization and then after capitalization on a pro forma basis. The results indicate that working capital, leverage, and solvency change dramatically in a negative direction, and airline rankings based on those ratios also change, which has implications for benchmarking performance
TPS Sizing for Access-to-Space Vehicles
A study was carried out to identify, develop, and benchmark simulation techniques needed for optimum thermal protection system (TPS) material selection and sizing for reusable launch vehicles. Fully viscous, chemically reacting, Navier-Stokes flow solutions over the Langley wing-body single stage to orbit (SSTO) configuration were generated and coupled with an in-depth conduction code. Results from the study provide detailed TPS heat shield materials selection and thickness sizing for the wing-body SSTO. These results are the first ever achieved through the use of a complete, trajectory based hypersonic, Navier-Stokes solution database. TPS designs were obtained for both laminar and turbulent entry trajectories using the Access-to-Space baseline materials such as tailorable advanced blanket insulation. The TPS design effects (materials selection and thickness) of coupling material characteristics to the aerothermal environment are illustrated. Finally, a sample validation case using the shuttle flight database is included
Comparison of Coupled Radiative Flow Solutions with Project Fire 2 Flight Data
A nonequilibrium, axisymmetric, Navier-Stokes flow solver with coupled radiation has been developed for use in the design or thermal protection systems for vehicles where radiation effects are important. The present method has been compared with an existing now and radiation solver and with the Project Fire 2 experimental data. Good agreement has been obtained over the entire Fire 2 trajectory with the experimentally determined values of the stagnation radiation intensity in the 0.2-6.2 eV range and with the total stagnation heating. The effects of a number of flow models are examined to determine which combination of physical models produces the best agreement with the experimental data. These models include radiation coupling, multitemperature thermal models, and finite rate chemistry. Finally, the computational efficiency of the present model is evaluated. The radiation properties model developed for this study is shown to offer significant computational savings compared to existing codes
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The influence of sub-100 nm scattering on high-energy electron beam lithography
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Understanding the mechanism of base development of hydrogen silsesquioxane
There have been numerous studies of electron beam exposed hydrogen silsesquioxane (HSQ) development conditions in order to improve the developer contrast. For TMAH based development, improvements were made by going to higher TMAH normalities and heating the developer. Yang and Berggren showed development of electron beam exposed (HSQ) by NaOH with added Na salts (various anions) significantly improves the contrast. Here, we study the contrast and etching rates of 100 keV exposed HSQ in NaOH in the presence of LiCl, NaCl, and KCl salts and use this as a segway to understand the mechanisms governing contrast during development HSQ development. The basic mechanism of development of HSQ can be understood by comparing to etching of quartz in basic solutions. Hydroxide ions act as nucleophiles which attack silicon. When a silicon-oxygen bond of the Si-O-Si matrix is broken, Si-O{sup -} and Si-OH are formed which can reversibly react to form the original structure. When a Si-H bond is broken via reaction with hydroxide, Si-O{sup -} and H{sub 2} gas are formed. Salts can change the etching rates as a function of dose in a non-linear fashion to increase etch contrast. Figs. 1, 2, and 3 show contrast curves for HSQ developed in 0.25 N sodium hydroxide and with the addition of NaCl, LiCl and KCl salts at several concentrations. NaCl addition resulted in the highest contrast. Contrast improves with additional salt concentration while sensitivity decreases. Interestingly enough, addition of salt decreases the removal of material of NaOH alone at higher doses while increasing the rate at lower concentrations. Addition of LiCl salts improves contrast over NaOH alone. Furthermore, the sensitivity at all doses increases as the LiCl concentration increases, a salting out effect. Similar to NaCl salt behavior, the addition of KCl salts, improves contrast at the expense of sensitivity. However, unlike NaCl, even at very high doses, KCl addition increases removal rate of HSQ. We propose explanations for these results by considering the change of nucleophilic strength of the OH{sup -} as a function of cation size and concentration, the ability for salts to block the surface etching, competition between bond breakage and recombination, and the density of the HSQ as a function of dose. Furthermore, we will discuss evolution of contrast as a function of development time in the context of our models
Formation of nanoscale structures by inductively coupled plasma etching
This paper will review the top down technique of ICP etching for the formation of nanometer scale structures. The increased difficulties of nanoscale etching will be described. However it will be shown and discussed that inductively coupled plasma (ICP) technology is well able to cope with the higher end of the nanoscale: features from 100nm down to about 40nm are relatively easy with current ICP technology. It is the ability of ICP to operate at low pressure yet with high plasma density and low (controllable) DC bias that helps greatly compared to simple reactive ion etching (RIE) and, though continual feature size reduction is increasingly challenging, improvements to ICP technology as well as improvements in masking are enabling sub-10nm features to be reached. Nanoscale ICP etching results will be illustrated in a range of materials and technologies. Techniques to facilitate etching (such as the use of cryogenic temperatures) and techniques to improve the mask performance will be described and illustrated
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Intergenerational connections through technology: Insights from the Technology Use in Later Life multi-site study
Abstract With enhanced challenges to maintain social connections especially during times of social distancing due to the COVID-19 pandemic, the need for technology solutions grow. Technologies have become interwoven into the daily lives for many older adults. The Technology Use in Later Life (TILL) study investigated how the perceptions and use of technology both can foster new and leverage existing intergenerational relationships. Through a mixed methods study engaging older adults aged 70 years of age and greater across rural and urban sites in Canada and the UK (N=37), participants described how the interconnection between technology and intergenerational relationships was an integral component to social connectedness with others. Through a qualitative descriptive approach, it was noted that older adults leveraged intergenerational relationships with family and friends to adjust to new technologies and to remain connected to adult children and grandchildren especially when there is high geographic separation between them. Especially during times of COVID-19, younger family members can play an important role to introduce and teach older adults how to use, technologies such as digital devices, computers, and social networking sites. Participants emphasized the benefits of intergenerational connections to adopt and use technology in later life noting flexibility and willingness to overcome barriers to technology adoption and remain connected across the generations. The adoption and uptake of technologies may continue as viable options during times of social distancing to support older persons to remain independent, age in place, in both age-friendly cities and across rural geographies during and post COVID-19
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Scanning X-ray Microscopy Investigations into the Electron BeamExposure Mechanism of Hydrogen Silsesquioxane Resists
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Fabrication and performance of nanoscale ultra-smooth programmed defects for EUV Lithography
We have developed processes for producing ultra-smooth nanoscale programmed substrate defects that have applications in areas such as thin film growth, EUV lithography, and defect inspection. Particle, line, pit, and scratch defects on the substrates between 40 and 140 nm wide 50 to 90 nm high have been successfully produced using e-beam lithograpy and plasma etching in both Silicon and Hydrosilsequioxane films. These programmed defect substrates have several advantages over those produced previously using gold nanoparticles or polystyrene latex spheres--most notably, the ability to precisely locate features and produce recessed as well as bump type features in ultra-smooth films. These programmed defects were used to develop techniques for film defect mitigation and results are discussed
Intergenerational Effects on the Impacts of Technology Use in Later Life: Insights from an International, Multi-Site Study
As the use of technology becomes further integrated into the daily lives of all persons, including older adults, it is important to investigate how the perceptions and use of technology intersect with intergenerational relationships. Based on the international multi-centered study Technology In Later Life (TILL), this paper emphasizes the perceptions of older adults and the interconnection between technology and intergenerational relationships are integral to social connectedness with others. Participants from rural and urban sites in Canada and the UK (n = 37) completed an online survey and attended a focus group. Descriptive and thematic analyses suggest that older adults are not technologically adverse and leverage intergenerational relationships with family and friends to adjust to new technologies and to remain connected to adult children and grandchildren, especially when there is high geographic separation between them. Participants referenced younger family members as having introduced them to, and having taught them how to use, technologies such as digital devices, computers, and social networking sites. The intergenerational support in the adoption of new technologies has important implications for helping older persons to remain independent and to age in place, in both age-friendly cities and in rural communities. The findings contribute to the growing literature in the fields of gerontology and gerontechnology on intergenerational influences and the impacts of technology use in later life and suggest the flexibility and willingness of older persons to adopt to new technologies as well as the value of intergenerational relationships for overcoming barriers to technology adoption
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