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61.
Jiho Yoo Sangdo Kim Hokyung Choi Youngjoon Rhim Jeonghwan Lim Sihyun Lee Allan J. Jacobson 《Journal of Electroceramics》2011,26(1-4):56-62
The oxygen partial pressure (pO2) dependence of the electrical conductivity of La0.2Sr0.8Cr0.2Fe0.8O3-?? (LSCrF) was obtained at T?=?750?C1060°C and pO2?=?10?18?0.5 atm. The slope of the plot of log ?? vs. log pO2 is ??1/5 in the p?Ctype region, pO2?=?10?5?10?1 atm. The p-n transition pO2 increases with increasing temperature. The activation energy for ionic conduction was estimated to be 0.86 eV from an Arrhenius plot of the minimum conductivity vs. reciprocal temperature. At temperatures below 942°C, a plateau in the conductivity isotherm suggests the presence of a two-phase region. Most likely, phase separation occurs to form a mixture of a perovskite phase and an oxygen vacancy ordered phase related to brownmillerite. 相似文献
62.
Abstract: Agar‐based nanocomposite films with different types of nanoclays, such as Cloisite Na+, Cloisite 30B, and Cloisite 20A, were prepared using a solvent casting method, and their tensile, water vapor barrier, and antimicrobial properties were tested. Tensile strength (TS), elongation at break (E), and water vapor permeability (WVP) of control agar film were 29.7 ± 1.7 MPa, 45.3 ± 9.6%, and (2.22 ± 0.19) × 10?9 g·m/m2·s·Pa, respectively. All the film properties tested, including transmittance, tensile properties, WVP, and X‐ray diffraction patterns, indicated that Cloisite Na+ was the most compatible with agar matrix. TS of the nanocomposite films prepared with 5% Cloisite Na+ increased by 18%, while WVP of the nanocomposite films decreased by 24% through nanoclay compounding. Among the agar/clay nanocomposite films tested, only agar/Cloisite 30B nanocomposite film showed a bacteriostatic function against Listeria monocytogenes. 相似文献
63.
As the need for the improvement of the productivity in the manufacturing process grows, industrial robots are brought out of the safety fences and used in the direct collaborative operation with human workers. Consequently, the intended and/or unintended contact between the human and the robot in the collaborative operation is no longer an extraordinary event and is a mundane possibility. The level of the risk of the collision depends on various quantities associated with the collision, for example, inertia, velocity, stiffness, and so on. MSI (manipulator safety index) which is based on HIC (head injury criteria) conventionally used in the automotive industry is one of the practically available measures to estimate the risk of the collision between the human and the manipulator. In this paper MSI is applied to evaluate the collision safety of a 7-DOF articulated human-arm-like manipulator. The risk of the collision could be reduced by choosing different postures without deviating from the given end-effector trajectory using the redundant degree of freedom in the 7-DOF manipulator. The paper shows how the redundant degree of the freedom is utilized to design safer trajectories and/or safer manipulator configurations among many available. A parametric analysis and simulation results for a given trajectory illustrate the usefulness of the concept of the trajectory design for alleviating the risk of the manipulator operation in the human–robot coexisting workspace. 相似文献
64.
Maesaengi (Capsosiphon fulvescens) was dehydrated in a single layer at drying air temperatures ranging from 50–80°C in a laboratory scale convective dryer
with an air velocity of 0.26 m/s. The effect of drying air temperature on the drying kinetic characteristics was determined.
Maesaengi was dried to equilibrium moisture content within 200–600 min under these drying conditions. Drying rate curves of maesaengi showed an initial short period of a constant drying rate, followed by a falling drying rate period. The moisture decrease
in the sample during dehydration was well described by the zero-order kinetic model. An Arrhenius-type equation was used to
test the effect of temperature on drying rate according to an activation energy value of 29.36 kJ/mol. 相似文献
65.
Fungal volatile organic compounds (FVOCs) contribution in olive oil aroma and volatile biogenesis during olive preprocessing storage
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66.
Thermophysical properties of molten germanium have been measured using the high-temperature electrostatic levitator at the Jet Propulsion Laboratory. Measured properties include the density, the thermal expansivity, the hemispherical total emissivity, the constant-pressure specific heat capacity, the surface tension, and the electrical resistivity. The measured density can be expressed by
liq=5.67×103–0.542 (T–T
m
) kg·m–3 from 1150 to 1400 K with T
m=1211.3 K, the volume expansion coefficient by =0.9656×10–4 K–1, and the hemispherical total emissivity at the melting temperature by
T, liq(T
m)=0.17. Assuming constant
T, liq(T)=0.17 in the liquid range that has been investigated, the constant-pressure specific heat was evaluated as a function of temperature. The surface tension over the same temperature range can be expressed by (T)=583–0.08(T–T
m) mN·m–1 and the temperature dependence of the electrical resistivity, when r
liq(T
m)=60·cm is used as a reference point, can be expressed by r
e, liq(T)=60+1.18×10–2(T–1211.3)·cm. The thermal conductivity, which was determined from the resistivity data using the Wiedemann–Franz–Lorenz law, is given by
liq(T )=49.43+2.90×10–2(T–T
m) W·m–1·K–1. 相似文献
67.
Sang Do Kim Kwang Jae Woo Soon Kwan Jeong Young Jun Rhim Si Hyun Lee 《Korean Journal of Chemical Engineering》2008,25(4):758-763
Present study was conducted for the purpose of producing low ash coal from LRC (low rank coals) such as lignite and sub-bituminous
coal through thermal extraction using polar solvent. Extraction from bituminous coal was also investigated for comparison.
NMP as a polar solvent was used. The ratio of coal to solvent was adjusted as 1: 10. Experimental conditions were established
which include the extraction temperature of 200–430 °C, initial applied pressure of 1–20 bar and extraction time of 0.5–2
hr were used. Extraction yield and ash content of extracted and residual coal were measured. The extraction yield increased
with the increase of extraction temperature, and the ash content of extracted coal decreased below 0.4% at 400 °C from the
raw coal samples that have the ash contents of 4–6%. According to the analysis of experiments results, fixed carbon and calorific
value increased, and H/C and O/C decreased. 相似文献
68.
Sung Min Rhim Heungjin Bak Seokmin Hong Ok Kyung Kim 《Journal of the American Ceramic Society》2000,83(12):3009-3013
The effects of heating rate on the sintering behavior and the dielectric properties of Ba0.7 Sr0.3 TiO3 ceramics prepared by boron-containing liquid-phase sintering were investigated. When 0.5 wt% B2 O3 was added to Ba0.7 Sr0.3 TiO3 , sintering was achieved at ∼1150°C, and the overdoped B2 O3 did not form an adequate amount of liquid phase or volatilize; it remained in the samples and formed a secondary phase. A transition broadening was observed as the heating rate increased. As the heating rate increased, the Curie temperature increased and the maximum dielectric constant ( k max ) at the Curie temperature decreased. This result is attributable to a decrease in the diffuseness parameter (δ) and the tetragonality ( c / a ). 相似文献
69.
Poly(vinyl alcohol)(PVA)/poly(acrylic acid)(PAA) and PVA/sulfosuccinic acid (SSA) membrane performances have been studied for the pervaporation separation of methyl tert‐butyl ether (MTBE)/methanol (MeOH) mixtures with varying operating temperatures, amount of cross‐linking agents, and feed compositions. Typically, the separation factor, about 4000, and the permeation rate, 10.1 g/m2/h, were obtained with PVA/PAA = 85/15 membrane for MTBE/MeOH = 80/20 mixtures at 50°C. For PVA/PAA membranes, it could be considered that the flux is affected by the structural changes of the membranes due to the cross‐linking and the free carboxylic acid group also took an important role in the separation characteristics through the hydrogen bonding with PVA and the feed components leading to the increase of flux. The latter membrane of the 5% SSA membrane shows the highest separation factor of 2095 with the flux of 12.79 g/m2/h for MTBE/MeOH = 80/20 mixtures at 30°C. Besides the swelling measurements were carried out for pure MTBE and MeOH, and MTBE/MeOH = 90/10, 80/20 mixtures using PVA/SSA membranes with varying SSA compositions. It has been recognized that there are two factors, the membrane network and the hydrogen bonding in the swelling measurements of PVA/SSA membranes. These two factors act interdependently on the membrane swelling. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1699–1707, 2000 相似文献
70.
Ki-Young Lee Sojung Shim Il-Soo Kim Hwangyou Oh Sunoh Kim Jae-Pyeong Ahn Seung-Han Park Hyewhon Rhim Heon-Jin Choi 《Nanoscale research letters》2010,5(2):410-415
We report on the compatibility of various nanowires with hippocampal neurons and the structural study of the neuron–nanowire
interface. Si, Ge, SiGe, and GaN nanowires are compatible with hippocampal neurons due to their native oxide, but ZnO nanowires
are toxic to neuron due to a release of Zn ion. The interfaces of fixed Si nanowire and hippocampal neuron, cross-sectional
samples, were prepared by focused ion beam and observed by transmission electron microscopy. The results showed that the processes
of neuron were adhered well on the nanowire without cleft. 相似文献