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991.
992.
Qualitative assessment provides a sound process for defining specific aspects of risk associated with potentially unstable slopes. Field observations, experience, field data, and back analysis from eleven past slope failures have been used to identify common and significant factors associated with the potential failure of coal waste embankments located in southwest Virginia. A database containing information about site location, characteristics, and conditions has been developed using Office of Surface Mining program narratives and engineering reports. It was observed that the pattern of failure was almost identical at each site and driven by the same phenomena. Degradation of the spoil material, accelerated by poor drainage conditions and periods of increased precipitation, lead to a decrease in interparticle strength and failure along a “lubricated,” or highly weathered, surface. The development of a rating system for the identification of potentially unstable coal waste embankments, based on the factors and characteristics reviewed here, will eventually lead to the implementation of a preventive maintenance program. Preventative maintenance will most likely need to include monitoring of the area, installation of a proper drainage system, and revegetation. 相似文献
993.
Kyle M. Allen Nick Auyeung Nima Rahmatian James F. Klausner Eric N. Coker 《JOM Journal of the Minerals, Metals and Materials Society》2013,65(12):1682-1693
The kinetics of 10 wt.% cobalt ferrite (CoFe2O4) in 8 mol.% yttria-stabilized zirconia, synthesized via the co-precipitation method and formed into a porous structure, are investigated in support of simulating the performance of a solar thermochemical reactor. Kinetic parameters for the thermal reduction (T-R) of CoFe2O4 at temperatures of 1325–1500°C were investigated by thermogravimetry. A nonlinear best fit of a uniform conversion model was used to determine kinetic parameters from experimental data. In the temperature range of 1375–1450°C, the activation energy and preexponential term were found to be 386 ± 13 kJ mol?1 and 8.8 × 109 ± 2.0 × 108 min?1, respectively, while increasing at higher temperatures. Simultaneous thermogravimetric analysis and differential scanning calorimetry studies showed an increase in the reaction rate of T-R upon the onset of melting (1440°C). Oxidation studies of the material using CO2 yield an activation energy and preexponential term of 52.1 ± 6.8 kJ mol?1 and 2.86 ± 0.2 min?1, respectively, which is in good agreement with past work. The reaction order for CO2 was determined to be 0.750 ± 0.08. The reaction kinetics for oxidation using CO2 were best described by a 3-D diffusion Jander model. 相似文献
994.
M. Hossein Taghavi Arshan Naji Leonid Belostotski James W. Haslett 《Analog Integrated Circuits and Signal Processing》2013,77(2):221-233
This paper discusses the use of mutli-path inductorless transimpedance amplifiers (TIAs), consisting of several different second-order shunt-feedback sub-TIAs (SF-sTIAs) driven by the photodiode, to break the single-stage technology-dependent transimpedance limit. The advantage of the MP-TIA that is explored in this work is in its third-order transfer function, which provides additional degrees of freedom in tailoring the performance. Pole and zero locations of the MP-TIA transfer function are examined and verified with behavioural simulations. The theoretical transimpedance limit for MP-TIAs based on two SF-sTIAs is derived. The possibility of further increasing the transimpedance limit vs bandwidth trade-off by combining three and four sub-TIAs is investigated with simulations. A transistor-level design example of an MP-TIA is presented. The 0.13-μm CMOS MP-TIA achieves the largest figure-of-merit among published TIAs. 相似文献
995.
Computability and Complexity in Self-assembly 总被引:1,自引:0,他引:1
James I. Lathrop Jack H. Lutz Matthew J. Patitz Scott M. Summers 《Theory of Computing Systems》2011,48(3):617-647
This paper explores the impact of geometry on computability and complexity in Winfree’s model of nanoscale self-assembly.
We work in the two-dimensional tile assembly model, i.e., in the discrete Euclidean plane ℤ×ℤ. Our first main theorem says
that there is a roughly quadratic function f such that a set A⊆ℤ+ is computably enumerable if and only if the set X
A
={(f(n),0)∣n∈A}—a simple representation of A as a set of points on the x-axis—self-assembles in Winfree’s sense. In contrast, our second main theorem says that there are decidable sets D⊆ℤ×ℤ that do not self-assemble in Winfree’s sense. 相似文献
996.
Congling Yin Guobao Li Tounan Jin Julian Tao James W. Richardson Chun-K. Loong Fuhui Liao Jianhua Lin 《Journal of Alloys and Compounds》2010,489(1):152-156
A new compound Ba5Sn1.1Mn3.9O15 has been synthesized at 1300 °C by solid-state reaction. The structure was characterized by X-ray, electron and neutron diffraction methods. Ba5Sn1.1Mn3.9O15 crystallizes in hexagonal space group P63/mmc with a = 5.717 Å and c = 23.534 Å. The magnetic measurement reveals that Ba5Sn1.1Mn3.9O15 has a spin glass transition at 7 K. 相似文献
997.
998.
999.
Yu Jin Xiangli Cui Udai P. Singh Alexander A. Chumanevich Brook Harmon Philip Cavicchia Anne B. Hofseth Venkata Kotakadi Brandy Stroud Suresh R. Volate Thomas G. Hurley James R. Hebert Lorne J. Hofseth 《Molecular nutrition & food research》2010,54(10):1506-1514
Chronic inflammation contributes to an increased risk for developing chronic conditions such as cardiovascular disease, diabetes, and cancer. A high “inflammatory load” is defined as elevated inflammation markers in blood or other tissues. We evaluated several markers of systemic inflammation from healthy adults and tested the hypothesis that two formulations of encapsulated fruit and vegetable juice powder concentrate with added berry powders (FVB) or without (FV) could impact markers of inflammatory load. Using a double‐blind, placebo‐controlled approach, 117 subjects were randomly assigned to receive placebo, FV, or FVB capsules. Blood was drawn at baseline and after 60 d of capsule consumption. We measured inflammatory markers (high sensitivity C‐Reactive Protein, Monocyte Chemotactic Protein‐1, Macrophage Inflammatory Protein 1‐β, and Regulated upon Activation, Normal T cell Expressed and Secreted), superoxide dismutase, and micronutrients (β‐carotene, vitamin C, and vitamin E). Results showed Monocyte Chemotactic Protein‐1, Macrophage Inflammatory Protein 1‐β, and RANTES levels were significantly reduced and superoxide dismutase and micronutrient levels were significantly increased in subjects consuming both FV and FVB, relative to placebo. Data suggest a potential health benefit by consuming either formulation of the encapsulated juice concentrates through their anti‐inflammatory properties. 相似文献
1000.
Simon Jessica R.; Howard James H. Jr.; Howard Darlene V. 《Canadian Metallurgical Quarterly》2010,24(4):534
Objective: Past research has investigated age differences in frontal-based decision making, but few studies have focused on the behavioral effects of striatal-based changes in healthy aging. Feedback learning has been found to vary with dopamine levels; increases in dopamine facilitate learning from positive feedback, whereas decreases facilitate learning from negative feedback. Given previous evidence of striatal dopamine depletion in healthy aging, we investigated behavioral differences between college-aged and healthy older adults using a feedback learning task that is sensitive to both frontal and striatal processes. Method: Seventeen college-aged (M = 18.9 years) and 24 healthy, older adults (M = 70.3 years) completed the Probabilistic Selection task, in which participants are trained on probabilistic stimulus-outcome information and then tested to determine whether they learned more from positive or negative feedback. Results: As a group, the older adults learned equally well from positive and negative feedback, whereas the college-aged group learned more from positive than negative feedback, F(1, 39) = 4.10, p effect = .3. However, these group differences were not due to older individuals being more balanced learners. Most individuals of both ages were balanced learners, but while all of the remaining young learners had a positive bias, the remaining older learners were split between those with positive and negative learning biases (χ2(2) = 6.12, p 相似文献