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941.
We couple a morphological study of an immiscible binary AB mixture with a micromechanical simulation to determine how the spatial distribution of the A and B domains and the interfacial region (interphase) affects the mechanical behavior of the blend. The morphological studies are conducted through a three-dimensional Cahn-Hilliard (CH) simulation. Through the CH calculations, we obtain the size and structure of the domains for different blend compositions. The output of the CH model serves as the input to the Lattice Spring Model (LSM), which consists of a three-dimensional network of springs. In particular, the location of the different phases is mapped onto the LSM lattice and the appropriate force constants are assigned to the LSM sites. A stress is applied to the LSM lattice and we calculate the elastic response of the material. We find that the local stress and strain fields are highly dependent on the morphology of the system. By integrating the morphological and mechanical models, we can isolate how modifications in the composition of the mixture affect the macroscopic behavior. Thus, we can establish how choices made in the components affect the ultimate performance of the material. 相似文献
942.
A rapid single-step method for the electrosynthesis of chloro and bromo complexes of palladium(II and IV), viz. M2[PdX4] and M2[PdX6], by the dissolution of a palladium anode in chloride or bromide containing media is described. Electrolysis of dilute HX solution in the presence of pyridine, 2,2′-bipyridyl or 1,10-phenanthroline gives rise to non-electrolytes, e.g. trans-[PdX2(py)2], [PdX2(bipy)] and [PdX2(phen)]. Anodic oxidation of palladium in HX medium in the presence of acetonitrile and benzonitrile also gives the non-electrolytes trans-[PdX2(CH3CH2NH2)2] and trans-[PdX2(C6H5CH2NH2)2], respectively. 相似文献
943.
In this paper, numerical simulation of three-dimensional supersonic flow in a duct is presented. The flow field in the duct is complex and can find its applications in the inlet of air-breathing engines. A unique streamwise marching Lagrangian method is employed for solving the steady Euler equations. The method was first initiated by Loh and Hui (1990) for 2-D steady supersonic flow computations and then extended to 3-D computation by the present authors Loh and Liou (1992). The new scheme is shown to be capable of accurately resolving complicated shock or contact discontinuities and their interactions. In all the computations, a free stream of Mach numberM=4 is considered.This article was processed using Springer-Verlag TEX Shock Waves macro package 1.0 and the AMS fonts, developed by the American Mathematical Society. 相似文献
944.
C.J. Lu H.M. Shen S.B. Ren Y.N. Wang 《Applied Physics A: Materials Science & Processing》1997,65(4-5):395-401
3 thin films is systematically studied by using X-ray diffraction (XRD). The PbTiO3 thin films with different average grain sizes were prepared on various substrates by a sol-gel process. The films on NaCl
and fused glass are randomly grain-oriented, while those on (111)Pt/Ti/SiO2/Si are highly {100} cubic index grain-oriented . It is found from the XRD patterns of the films on NaCl that with decreasing
average grain size from 230 to 80 nm, the intensities of high h index (h>l) peaks (hkl), such as (100), (110), (200), (201),
(210), (211), etc., decrease rapidly and ultimately disappear, whereas another set of peaks (lkh), including (001), (002),
(102), (112), etc., are still intense. This interesting result suggests that at grain size below a certain critical size an
increasing number of grains no longer show 90°-domains, which is confirmed by TEM observations. Meanwhile, X-ray evidence
of such a grain-size-related absence of 90°-domains is also found for PbTiO3 films on Pt(111) and fused-glass substrates. The volume fractions of single-domain grains (without 90°-domains) in the films
are estimated from their XRD patterns. By combining SEM and TEM investigations, the critical grain size for the formation
of 90°-domains is further determined to be near 200 nm.
Received: 19 December 1996/Accepted: 24 March 1997 相似文献
945.
946.
On the stokes problem in Lipschitz domains 总被引:3,自引:0,他引:3
947.
C. Basu 《Il Nuovo Cimento D》1992,14(9):947-953
Summary A simple method has been suggested to estimate the acoustic characteristics of porous structure from a hybrid model—a hybridisation
of Biot's phenomenological model and the microscopic multiple-scattering theory which introduces the idea of an effective
tortuosity. Without using any adjustable parameter this model may be used to provide rough estimates of the tortuosity, the
fast, the shear and the slow sound speeds. The predictions are compared with observation on water-saturated glass bead samples.
The author of this paper has agreed to not receive the proofs for correction. 相似文献
948.
Cheng-kung Liu John A. Cuculo Thomas C. Allen A. Willem Degroot 《Journal of Polymer Science.Polymer Physics》1991,29(2):181-196
Fiber formation via the cellulose/ammonia/ammonium thiocyanate system by wet spinning has been investigated. This report presents a characterization of the structure and tensile properties of fibers spun under various coagulation conditions. Microscopic observations showed that the molecular size of coagulant was the dominant factor governing the crosssectional shape of the fibers. Density, birefringence, and crystallinity data indicated that a higher cellulose concentration and lower coagulation temperature favored development of a fiber with a denser and more oriented structure. Under optimum conditions, a welldefined fibrillar structure was obtained. Fiber tensile property measurements suggested the existence of a linear relationship between the fiber breaking tenacity and the product of the square of the Hermans' orientation factor and the infrared crystallinity index. 相似文献
949.
A new porphyrin, peroxyacetic acid uroporphyrin I, has been isolated from the urine of patients with congenital erythropoietic porphyria by reversed phase high performance liquid chromatography. The porphyrin was characterized by high resolution mass spectrometry and by typical chemical reactions of a peroxyacid. 相似文献
950.
Muon irradiation of pure liquid 3‐chloropropene, CH2=CH-CH2Cl, yields a primary radical, \dot\mboxCH2-CHMu-CH2Cl, and a secondary radical, MuCH2-\rm\dot\mboxCH-CH2Cl. 2‐methyl‐3‐chloropropene yields only the tertiary radical, MuCH2-\rm\dot\mboxC(CH3)-CH2Cl. These three chloroalkyl radicals have been characterized by μSR and μLCR, and the hyperfine coupling constants (hfcs)
have been determined over a range of temperatures, either in the pure liquid precursor or in concentrated solution. The temperature
variation of the hfcs has been analyzed to obtain estimates of the barrier to internal rotation about the C_\alpha-C_\beta
axis for various alkyl groups, and also their minimum energy conformations, i.e. their orientations with respect to the axis
of the 2p_z orbital of the unpaired electron. The tertiary radical is particularly interesting because all three methyl‐like
groups, -CH3,-CH2Cl and -CH2Mu, are represented. The results can be compared to electron spin resonance data for analogous radicals, to provide information
on the effects of Mu substitution for H.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献