3,646 research outputs found
Application of Cryogenic Treatment to Extend the Life of the TiAlN-Coated Tungsten Carbide Milling Cutter
Cutting tools are important to the manufacturing industry since they will affect production efficiency and product quality. Cryogenic treatment can improve the material properties by decreasing residual stress, stabilizing dimensional accuracy, and increasing wear resistance. The purpose of this study is to investigate the feasibility and effect of cryogenic treatment on the performance of TiAlN-coated tungsten carbide milling cutters for machining the Inconel alloy 625 in terms of different testing methods (e.g., hardness, wear resistance, residual stress, microstructure, and tool life test). Experimental results indicate that after cryogenic treatment there is less wear, the microstructure is denser, residual stress is decreased, the adhesion of coating and tungsten carbide is improved, and the tool life is effectively improved
Edited NSSL meso-scale upper air network data in southwestern Oklahoma, 1966 and 1967
Cover title."Atmospheric General Circulation Technical Document No. 1.
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Compressed Statistical Testing and Application to Radar
We present compressed statistical testing (CST) with an illustrative application to radar target detection. We characterize an optimality condition for a compressed domain test to yield the same result as the corresponding test in the uncompressed domain. We demonstrate by simulation that under high SNR, a likelihood ratio test with compressed samples at 3.3x or even higher compression ratio can achieve detection performance comparable to that with uncompressed data. For example, our compressed domain Sample Matrix Inversion test for radar target detection can achieve constant false alarm rate (CFAR) performance similar to the corresponding test in the raw data domain. By exploiting signal sparsity in the target and interference returns, compressive sensing based CST can incur a much lower processing cost in statistical training and decision making, and can therefore enable a variety of distributed applications such as target detection on resource limited mobile devices.Engineering and Applied Science
Feedback first: the surprisingly weak effects of magnetic fields, viscosity, conduction, and metal diffusion on galaxy formation
Using high-resolution simulations with explicit treatment of stellar feedback
physics based on the FIRE (Feedback in Realistic Environments) project, we
study how galaxy formation and the interstellar medium (ISM) are affected by
magnetic fields, anisotropic Spitzer-Braginskii conduction and viscosity, and
sub-grid metal diffusion from unresolved turbulence. We consider controlled
simulations of isolated (non-cosmological) galaxies but also a limited set of
cosmological "zoom-in" simulations. Although simulations have shown significant
effects from these physics with weak or absent stellar feedback, the effects
are much weaker than those of stellar feedback when the latter is modeled
explicitly. The additional physics have no systematic effect on galactic star
formation rates (SFRs) . In contrast, removing stellar feedback leads to SFRs
being over-predicted by factors of . Without feedback, neither
galactic winds nor volume filling hot-phase gas exist, and discs tend to
runaway collapse to ultra-thin scale-heights with unphysically dense clumps
congregating at the galactic center. With stellar feedback, a multi-phase,
turbulent medium with galactic fountains and winds is established. At currently
achievable resolutions and for the investigated halo mass range
, the additional physics investigated here (MHD,
conduction, viscosity, metal diffusion) have only weak (-level)
effects on regulating SFR and altering the balance of phases, outflows, or the
energy in ISM turbulence, consistent with simple equipartition arguments. We
conclude that galactic star formation and the ISM are primarily governed by a
combination of turbulence, gravitational instabilities, and feedback. We add
the caveat that AGN feedback is not included in the present work
Nonstoichiometric doping and Bi antisite defect in single crystal Bi2Se3
We studied the defects of Bi2Se3 generated from Bridgman growth of
stoichiometric and nonstoichiometric self-fluxes. Growth habit, lattice size,
and transport properties are strongly affected by the types of defect
generated. Major defect types of Bi_Se antisite and partial Bi_2-layer
intercalation are identified through combined studies of direct atomic-scale
imaging with scanning transmission electron microscopy (STEM) in conjunction
with energy-dispersive X-ray spectroscopy (STEM-EDX), X-ray diffraction, and
Hall effect measurements. We propose a consistent explanation to the origin of
defect type, growth morphology, and transport property.Comment: 5 pages, 5 figure
Minimizing energy demand and environmental impact for sustainable NH3 and H2O2 production—A perspective on contributions from thermal, electro-, and photo-catalysis
There is an urgent need to provide adequate and sustainable supplies of water and food to satisfy the demand of an increasing population. Catalysis plays important roles in meeting these needs by facilitating the synthesis of hydrogen peroxide that is used in water decontamination and chemicals production, and ammonia that is used as fertilizer. However, these chemicals are currently produced with processes that are either very energy-intensive or environmentally unfriendly. This article offers the perspectives of the challenges and opportunities in the production of these chemicals, focusing on the roles of catalysis in more sustainable, alternative production methods that minimize energy consumption and environmental impact. While not intended to be a comprehensive review, the article provides a critical review of selected literature relevant to its objectives, discusses areas needed for further research, and potential new directions inspired by new developments in related fields. For each chemical, production by thermal, electro-, and photo-excited processes are discussed. Problems that are common to these approaches and their differences are identified and possible solutions suggested
The Role of E-Books in the Future of the Supply Chain of the Publishing Industry
The intent of this paper is to explore the future role of ebooks in the publishing industry. Emphasis is put on the impact it has on the supply chain of the industry. Issues dealing with the legal ramifications and financial implications, such as sales taxes, will also be addressed. The first section describes characteristics of e-books and the current developments in e-books from the consumer’s point of view. With the handling of the content of publications in digital form, intellectual property rights will become more complex and will require new regulations to deal with the new medium. These and other related legal issues are addressed in the third section. With the likelihood of utilizing the Internet for the distribution of the e-book to consumers, the collection of sales taxes will be difficult for government agencies to handle. The situation will be further complicated due to the globalization of the market place. Which policies are in effect, how will they are enforced, and who are responsible for their collection are emerging issues that will need to be addressed in the global and local arenas. Then it will be followed by the impact it has on the supply chain of the industry. For example, one of the benefits of ebooks is the reduction of logistical costs throughout the supply chain. Also, due to the ease of distribution, there most likely will be consolidation of certain levels within the supply chain. It may trigger a shift of competitive power among the various levels. The likely scenario of the future business environment of the publishing industry is discussed in the concluding section
Survival of Hendra Virus in the Environment: Modelling the Effect of Temperature
Hendra virus (HeV), a highly pathogenic zoonotic paramyxovirus recently emerged from bats, is a major concern to the horse industry in Australia. Previous research has shown that higher temperatures led to lower virus survival rates in the laboratory. We develop a model of survival of HeV in the environment as influenced by temperature. We used 20 years of daily temperature at six locations spanning the geographic range of reported HeV incidents to simulate the temporal and spatial impacts of temperature on HeV survival. At any location, simulated virus survival was greater in winter than in summer, and in any month of the year, survival was higher in higher latitudes. At any location, year-to-year variation in virus survival 24 h post-excretion was substantial and was as large as the difference between locations. Survival was higher in microhabitats with lower than ambient temperature, and when environmental exposure was shorter. The within-year pattern of virus survival mirrored the cumulative within-year occurrence of reported HeV cases, although there were no overall differences in survival in HeV case years and non-case years. The model examines the effect of temperature in isolation; actual virus survivability will reflect the effect of additional environmental factor
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