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81.
Mamiko Hori Cécile Pagnoux Jean-François Baumard Masayuki Nogami 《Journal of Materials Science》2007,42(1):80-86
A new method is proposed to produce gold nanoparticles (GNP) by in situ reduction of a gold salt dissolved in water. The reducing
agent used is Tiron instead of the citrate anion most often mentioned in literature. The influence of various parameters has
been investigated, such as the content of Tiron with respect to that of the precursor of gold HAuCl4, or the initial pH of the solution after mixing of reactants. It is shown that Tiron also exerts a positive influence as
a dispersant, which impedes agglomeration of gold nanoparticles. The typical average size of GNP synthesized in the present
work is close to 7 nm. 相似文献
82.
83.
Reduction of flash generated in a gas vent is of great concern for manufacturers of electronic parts. The present study proposes a theoretical model for flash generation through consideration of flow characteristics in a gas vent. The model predicts the factors controlling flash, i.e., material parameters such as zero‐shear viscosity, crystallization temperature, thermal conductivity, and heat capacity, and process parameters such as injection and mold wall temperatures, packing pressure, and the clearance of a gas vent. On the other hand, we measure the amount of flash generated in the molding of poly(phenylene sulfide) (PPS) composites containing glass fiber and spherical fillers (CaCO3 or Al2O3). Flash reduces with decreasing size of spherical fillers. These experimental data are successfully interpreted using the flash model. Polym. Eng. Sci., 45:198–206, 2005. © 2005 Society of Plastics Engineers 相似文献
84.
A three‐dimensional flow simulation for epoxy casting has been developed. A control‐volume‐based finite‐element method is employed, containing a conservative upwind formulation for the advection terms and equal order interpolations for all variables. This simulation predicts the non‐isothermal and reactive flow behavior under the gravity. The viscosity and reaction‐rate parameters were estimated by using a dynamic rheometer and a differential scanning calorimeter. The predicted flow front advancement and temperature profiles in the calculation domain similar to the mold cavity were in close agreement with the corresponding experimental results. The variation of epoxy surface configuration with flow rate also showed the same tendency between the prediction and the experiment. This simulation seems to be applicable not only to the epoxy casting, but also to other molding processes of various thermoset resins. POLYM. ENG. SCI. 45:364–374, 2005. © 2005 Society of Plastics Engineers. 相似文献
85.
M. K. Bakhadyrkhanov O. É. Sattarov Kh. M. Iliev K. S. Ayupov Tuérdi Umaier 《Semiconductors》2005,39(7):789-791
It is experimentally ascertained that light stimulates the negative magnetoresistance observed in a high electric field in silicon doped with boron and manganese. The optimum conditions (the electric field, temperature, illumination, and resistivity of the material) for observation of the largest magnitude of negative magnetoresistance in (Si:B):Mn are determined. The dependence of the negative magnetoresistance on the concentration of compensating impurity is established. 相似文献
86.
The stress intensity factors for a short crack partially penetrating an inclusion of arbitrary shape
Some approximate solutions for predicting the stress intensity factor of a short crack penetrating an inclusion of arbitrary
shape have been developed under mode I and mode II loading conditions. The derivation of the fundamental formula is based
on the transformation toughening theory. The transformation strains in the inclusion are induced by the crack-tip field and
remotely applied stresses, and approximately evaluated by the Eshelby equivalent inclusion theory. As validated by detailed
finite element (FE) analyses, the developed solutions have good accuracy for different inclusion shape and for a wide range
of modulus ratio between inclusion and matrix material. 相似文献
87.
An overview of nondestructive evaluation methods 总被引:1,自引:0,他引:1
Marvin Trimm 《Journal of Failure Analysis and Prevention》2003,3(3):17-31
ondestructive evaluation is described as nondestructive testing (NDT), nondestructive inspection (NDI), and nondestructive
examination (NDE). The activities associated with the evaluation include testing, inspection, and examination and primarily
involve looking at (or through) and/or measuring some characteristic of an object. Frequently there is a desire to determine
some characteristic of the object or to determine whether the object contains irregularities, discontinuities, or flaws. These
examinations, inspections, or tests are used to determine the physical soundness of a material without impairing its usefulness.
Nondestructive evaluation is a powerful tool that can help assure safety, quality, and reliability; increase productivity;
decrease liability; protect the environment; and save money. In this article, nondestructive evaluation is represented by
the acronym NDE. 相似文献
88.
Nguyen An Tien I. Ya. Mittova O. V. Almjasheva S. A. Kirillova V. V. Gusarov 《Glass Physics and Chemistry》2008,34(6):756-761
Nanocrystalline LaFeO3 is prepared by the dehydration of coprecipitated lanthanum and iron(III) hydroxides. It is shown that the behavior of the samples during heating and the size distribution of LaFeO3 nanocrystals can be considerably different depending on the scheme used for coprecipitation of lanthanum and iron hydroxides; independently of the method employed for coprecipitation of the initial compounds, sintering of the samples at 950°C leads to the formation of lanthanum orthoferrite crystals up to 100 nm in size. 相似文献
89.
Vjacheslav V. Zuev 《Journal of Polymer Research》2008,15(5):351-356
Functionalized polyanilines containing biphenyl, terphenyl, carbazole, anthracene, and 4-n-hexylphenyl moieties were synthesized though the reaction of polyaniline in emeraldine base form with sodium salt of corresponding
vinylketoaromatics with quantitative yields. Polymers were characterized with Fourier transform infrared spectroscopy, proton
nuclear magnetic resonance spectroscopy, and thermogravimetry. The emission characteristics of these polymers in N-methyl-2-pyrrolidone solution were examined. The functionalized polyanilines exhibited an intense green emission. 相似文献
90.
We propose two new antidiffusive schemes for advection (or linear transport), one of them being a mixture of Roe’s Super-Bee
scheme and of the “Ultra-Bee” scheme. We show how to apply these schemes to treat time-dependent first order Hamilton–Jacobi–Bellman
equations with discontinuous initial data, possibly infinitely-valued. Numerical tests are proposed, in one and two space
dimensions, in order to validate the methods
AMS subject classifications. Primary 65M12, Secondary 58J47 相似文献