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ESTIMATED S-N CURVE FOR NODULAR CAST IRON: A STEERING KNUCKLE CASE STUDY
M. JIMENEZ,J. MARTINEZ,U. FIGUEROA,L. ALTAMIRANO 한국자동차공학회 2014 International journal of automotive technology Vol.15 No.7
Durability assessment is performed to establish the damage applied by loads and the number of load cyclesversus S-N curves. This information is evaluated using a fatigue damage hypothesis. A new relationship is proposed toestimate the S-N curve of nodular cast iron, based on its ultimate strength, using a case study of a steering knuckle componentunder bending load. Finite element simulation was performed to obtain the maximum stresses in the component using PatranV2012.2 and Nastran V2008 software. Correction factors accounted for surface finish, type of load and level of reliability. Actual and proposed predictions were evaluated using experimental results. The main aim of this work was to design a fatiguetest, with a limited amount of information, through finite element simulation and tensile strength. The main advantage of thisrelationship over the other methods for estimating an S-N curve, is to improve life prediction at the boundary of low and highcycle fatigue with a simple relationship and without a series of tests to identify the S-N curve, thus simplifying durabilityassessment with a limited amount of information. The proposed relationship improved the life prediction by an average of10% in the case study.
Detection of Iron Phases Presents in Archaeological Artifacts by Raman Spectroscopy
( A. L. Barbosa ),( C. Jimenez ),( J. A. Mosquera ) 한국부식방식학회(구 한국부식학회) 2018 Corrosion Science and Technology Vol.17 No.2
The compounds associated with corrosion, in metallic archaeological samples of carbon steel of insular origin were evaluated to establish their degree of deterioration and structural damage against air pollution. The iron phases present in samples of archaeological artifacts were detected by Raman spectroscopy and confocal Raman microcopy. These samples mainly exhibited ing mainly β-FeO(OH) type goethite oxyhydroxides and small amounts of akaganeite α-FeO(OH) lepidocrocite γ-FeO(OH) due to dominant chloride in a marine environment and non-stoichiometric oxyhydroxides Fe (II + / III +) as indicators of early corrosion. Some parts showed the presence of magnetic maghemite indicating high corrosion. γ-FeO(OH) is a precursor of phases associated with advanced marine corrosion. By studying its decomposition by Raman spectroscopy, it was synthesized with the following sequence: γ-FeO(OH) → α-FeO(OH) + γ-FeO(OH), →γ-Fe<sub>2</sub>O<sub>3</sub>+ Fe<sub>3</sub>O<sub>4</sub>. Ferric compounds provided evidence for the effect of intensity of laser on them, constituting a very useful input for the characterization of oxidation of iron in this type of artifacts. Thus, destructive analysis techniques should be avoided in addition to the use of small amounts of specimen.
Hodzic, Alma,Kasibhatla, Prasad S.,Jo, Duseong S.,Cappa, Christopher D.,Jimenez, Jose L.,Madronich, Sasha,Park, Rokjin J. Copernicus GmbH 2016 Atmospheric Chemistry and Physics Vol.16 No.12
<P>Abstract. Recent laboratory studies suggest that secondary organic aerosol (SOA) formation rates are higher than assumed in current models. There is also evidence that SOA removal by dry and wet deposition occurs more efficiently than some current models suggest and that photolysis and heterogeneous oxidation may be important (but currently ignored) SOA sinks. Here, we have updated the global GEOS-Chem model to include this new information on formation (i.e., wall-corrected yields and emissions of semi-volatile and intermediate volatility organic compounds) and on removal processes (photolysis and heterogeneous oxidation). We compare simulated SOA from various model configurations against ground, aircraft and satellite measurements to assess the extent to which these improved representations of SOA formation and removal processes are consistent with observed characteristics of the SOA distribution. The updated model presents a more dynamic picture of the life cycle of atmospheric SOA, with production rates 3.9 times higher and sinks a factor of 3.6 more efficient than in the base model. In particular, the updated model predicts larger SOA concentrations in the boundary layer and lower concentrations in the upper troposphere, leading to better agreement with surface and aircraft measurements of organic aerosol compared to the base model. Our analysis thus suggests that the long-standing discrepancy in model predictions of the vertical SOA distribution can now be resolved, at least in part, by a stronger source and stronger sinks leading to a shorter lifetime. The predicted global SOA burden in the updated model is 0.88 Tg and the corresponding direct radiative effect at top of the atmosphere is −0.33 W m−2, which is comparable to recent model estimates constrained by observations. The updated model predicts a population-weighed global mean surface SOA concentration that is a factor of 2 higher than in the base model, suggesting the need for a reanalysis of the contribution of SOA to PM pollution-related human health effects. The potential importance of our estimates highlights the need for more extensive field and laboratory studies focused on characterizing organic aerosol removal mechanisms and rates. </P>
Zetina-Cordoba, P.,Ortega-Cerrilla, M.E.,Torres-Esqueda, M.T. Sanchez,Herrera-Haro, J.G.,Ortega-Jimenez, E.,Reta-Mendiola, J.L.,Vilaboa-Arroniz, J. Asian Australasian Association of Animal Productio 2012 Animal Bioscience Vol.25 No.8
The effect of duckweed (DW) supplementation was evaluated on dry matter intake (DMI), presence and duration of estrus, percentage of ewes repeating estrus and pregnancy rate, as well as the concentration of progesterone ($P_4$) in multiparous crossbred ewes from Pelibuey, Dorper, and Katahdin breeds, fed with Taiwan grass hay (TWH). Eighteen ewes with $39.7{\pm}4kg$ mean body weight, kept in individual pens, were randomly assigned to one of the following treatments: $T_1$: TWH, $T_2$: TWH plus 200 g DW, $T_3$: TWH plus 300 g DW. The ewes were synchronized with 40 mg fluorogestone acetate (FGA) and 400 UI equine chorionic gonadotropin (eCG). Data were analyzed as a completely randomized design using the GLM procedure. DW supplementation had no effect on dry matter intake (p>0.05); however, a slight decrease of TWH intake was observed as DW supplementation increased. No differences (p>0.05) were found in the beginning of estrus, percentage of ewes presenting it, its duration, or pregnancy rate. There were no differences (p>0.05) on $P_4$ concentration among treatments, or $treatment{\times}period$ interaction (p>0.05). However the period was significant (p<0.01), since the $P_4$ levels increased as time increased after the removal of the FGA device and eCG application.