Preserving \u27His Masters\u27 Voice\u27: the archival significance of master recordings

Master recordings as products created by the music industry are some of the greatest time capsules in American culture. Throughout the history of the music industry master recordings received little attention and were not appreciated for the informational and evidential values held within the recordings. American archival theory provides the solution to help prevent the loss of master recordings and hence the loss of a piece of America\u27s culture. Through archival preservation and partnerships between record companies and independent archives, master recordings and the American culture contained within them have a better chance than ever of surviving for many years to come

Cost-performance analysis of silicon carbide fibers

Side-by-side studies of tensile strength and high-temperature exposures were conducted for High-Nicalon Type S, Sylramic, and Laser-Printed Silicon Carbide fibers. This battery of tests supports the well-known superior properties of CVD-derived Silicon Carbide, such as Specialty Materials’ SCS Ultra. SCS Ultra, however, is derived from CVD onto a continuous core filament substrate, hence it can only be produced in large diameter continuous filaments (90-140 µm). In contrast, laser-printing of SiC fibers relies on self-seeded Laser-Induced Chemical Vapor Deposition, which does away with the core filament substrate requirement, achieving much smaller diameters (adjustable between 14 and 50 µm) and growth rates, while replicating SCS Ultra’s superior properties. This paper also discusses economic projections for laser-printed SiC fiber production. Each laser beam produces one continuous filament. Lasers are currently at $100/beam with the cost expected to continue to fall to$50/beam in the next 5 years. Current fiber laser printers are at 384 beams per unit. This means 120 laser printers are needed per metric ton of 25 µm SiC fiber per year. This places capital equipment costs at a fraction of current polymer-derived SiC fibers production, with specific energetic requirements (kW-h/Ton) and raw material exploitation (kg out / kg in) improvements by one order of magnitude or greater. Long-term projections for mass-produced laser-printed fibers present a realistic pathway to $1000/lb CVD-quality SiC fibers

How not to measure the tensile strength of high-modulus fibers

Monofilament tensile strength and Young\u27s Modulus measurements are standardized in ASTM C1557 - 14. The Standard prescribes the use of mounting tabs that are “appropriately designed to be self-aligning if possible, and as thin as practicable to minimize fiber misalignment.” We have now shown through analysis, and verified through experiments, that this method can be expected to have an increasingly negative impact on strength measurement as the Young’s modulus and/or fiber diameter increases. We show that translational and angular misalignments are in fact neither measurable nor controllable in the Standard, and that even half the suggested misalignment tolerance can have an order of magnitude deleterious impact on the measured strength. The Standard notes that there is no standard gage length but that current practice is to use 1 . We have found that, for the test procedure advocated by the Standard, the gage length cannot be considered independently of the fiber diameter, and that there is an optimal ratio that will minimize the influence of perturbations induced by the test apparatus. The standard recommends recovering the fracture surfaces to measure the fiber diameter. However, it acknowledges that stiff fibers tend to shatter upon failure. This is in agreement with our experience with high-modulus Silicon Carbide ceramic fibers tensile tests, which shatter into small fragments, sometimes over the entire gage length. In an attempt to alleviate fiber fragmentation, the standard suggests vacuum grease to dampen fiber fracture. Experiments with fibers 15-50 µm in diameter and a Young’s modulus over 350 GPa resulted in complete fragmentation even when covered with vacuum grease. We found that using wax instead offered a better preservation of the fracture surface allowing for areal measurements. The Standard considers a tensile test to be valid when fracture occurs within the gage length of the test fiber. Our experiments rigorously following the Standard with high modulus (\u3e300 GPa) fibers (diameter 15-50 µm) covered with vacuum grease always resulted in a fractures occurring at the grip over 90% of the time. To prepare samples for the tensile strength measurement procedure, the Standard specifies: “Randomly choose, and carefully separate, a suitable single-fiber from the bundle or fiber spool.” We observed that the process of teasing a monofilament out of a tow is not random. Indeed, the separation of a monofilament from a bundle is a self-selecting process that is biased towards minimally flawed single-fibers. The Standard assumes a Weibull distribution of tensile strengths. This assumption is legitimate and in agreement with statistical failure analysis. A legitimate question is whether eliminating a source of perturbation has an effect on the Weibull statistics. Indeed the case can be made that the current standard, by restricting the measurable tensile strength would have the effect of artificially increasing the Weibull modulus, making the fiber quality appear to be more consistent that it actually is. This article introduces a new testing procedure, which circumvents the limitations imposed by the Standard. Experiments consistently show that the Standard tensile strength measurement procedure systematically underreports, sometimes severely, the strength of high-modulus filaments and overreports the Weibull modulus

Exploiting cross-channel quantizer error correlation in time-interleaved analog-to-digital converters

Uniform quantizers are often modeled as additive uncorrelated noise sources. This paper explores the validity of the additive noise model in the environment of time-interleaved A/D converters. Cross-channel quantizer error correlation is an important discrepancy that arises for channel time delays in close proximity. It is demonstrated through simulation that negative error correlation occurs for different granularity quantizers in close proximity. Statistical analysis is presented to characterize error correlation between quantizers with different granularity. A technique exploiting this correlation often yields significant performance gains above the optimal additive noise model solution.Fullbright FellowshipIrwin Mark Jacobs and Joan Klein Jacobs Presidential FellowshipTexas Instruments Incorporated. Leadership University Consortium ProgramBAE SystemsAnalog Devices, inc.Lincoln Laborator

The association of ideal cardiovascular health with incident type 2 diabetes mellitus: the Multi-Ethnic Study of Atherosclerosis

Levels of ideal cardiovascular health (ICH) and incident type 2 diabetes mellitus have not been examined in a multiethnic population. We assessed the total and race/ethnicity-specific incidence of diabetes based on American Heart Association (AHA) ICH components

Bandwidth Control and Symmetry Breaking in a Mott-Hubbard Correlated Metal

In Mott materials strong electron correlation yields a spectrum of complex electronic structures. Recent synthesis advancements open realistic opportunities for harnessing Mott physics to design transformative devices. However, a major bottleneck in realizing such devices remains the lack of control over the electron correlation strength. This stems from the complexity of the electronic structure, which often veils the basic mechanisms underlying the correlation strength. Here, we present control of the correlation strength by tuning the degree of orbital overlap using picometer-scale lattice engineering. We illustrate how bandwidth control and concurrent symmetry breaking can govern the electronic structure of a correlated $SrVO_3$ model system. We show how tensile and compressive biaxial strain oppositely affect the $SrVO_3$ in-plane and out-of-plane orbital occupancy, resulting in the partial alleviation of the orbital degeneracy. We derive and explain the spectral weight redistribution under strain and illustrate how high tensile strain drives the system towards a Mott insulating state. Implementation of such concepts will drive correlated electron phenomena closer towards new solid state devices and circuits. These findings therefore pave the way for understanding and controlling electron correlation in a broad range of functional materials, driving this powerful resource for novel electronics closer towards practical realization