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991.
Z. Denchev A. Nogales I. ics T. A. Ezquerra F. J. Balt‐Calleja 《Journal of Polymer Science.Polymer Physics》2001,39(9):881-894
A simultaneous wide‐angle and small‐angle X‐ray scattering study of two poly(ethylene naphthalene 2,6‐dicarboxylate) samples crystallized from the glassy state at different annealing temperatures for different annealing times was carried out with synchrotron radiation. Either single or dual melting was induced in the samples, as confirmed by differential scanning calorimetry (DSC). The correlation function and interface distribution function were calculated to evaluate microstructural parameters such as the long spacing, the thickness of the amorphous and crystalline phases, and the width of the size distributions. The sample with dual melting behavior exhibited an abrupt increase of all microstructural parameters at temperatures above the melting of the lowest endotherm, whereas the sample revealing a single melting endotherm did not show such a sudden change. This finding agrees with the concept that the appearance of two melting peaks in DSC traces can be explained by the dual lamellar stacking model. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 881–894, 2001 相似文献
992.
An explicit full-field expression of the Green's functions for anisotropic piezoelectric bimaterials with a slipping interface
is derived. When the electro-elastic singularity reduces to a pure dislocation in displacement and electric potential, interaction
energy between the dislocation and the bimaterials is obtained explicitly while the generalized force on the dislocation is
given in a real form which is also valid for degenerate materials. The investigation demonstrates that the boundary conditions
at the slipping interface between two piezoelectric materials will exert a prominent influence on the mobility of the dislocation.
Project supported by the National Natural Science Foundation of China (No. 59635140). 相似文献
993.
In this article,the authors deal with the Cauchy problem of a nonlinear par- abolic equation with variable density and absorption.By using energy methods.the an- thors prove that the interfaces can disappear in finite time under some assumption on the density functions. 相似文献
994.
UMTS radio network evaluation and optimization beyond snapshots 总被引:1,自引:0,他引:1
Andreas Eisenblätter Hans-Florian Geerdes Thorsten Koch Alexander Martin Roland Wessäly 《Mathematical Methods of Operations Research》2006,63(1):1-29
A new evaluation scheme for universal mobile telecommunications system (UMTS) radio networks is introduced. The approach takes
the complex coupling of coverage and capacity through interference into account. Cell load estimates, otherwise obtained through
Monte-Carlo simulation, can now be approximated without time-consuming iterative simulations on user snapshots. The two cornerstones
are the generalization of interference coupling matrices from user snapshots to average load and the emulation of load control
by an analytical scaling scheme. Building on the new evaluation scheme, two novel radio network optimization algorithms are
presented: an efficient local search procedure and a mixed integer program that aims at designing the coupling matrix. Computational
experiments for optimizing antenna tilts show that our new approaches outperform traditional snapshot models 相似文献
995.
S. M. Zen’kovskaya V. A. Novosyadlyi 《Computational Mathematics and Mathematical Physics》2008,48(9):1669-1679
The effect of single- and two-frequency vibrations on the behavior of a system consisting of two homogeneous viscous fluids bounded by rigid walls is analyzed. It is assumed that the system as a whole is under vertical vibrations obeying a certain law. An eigenvalue problem is obtained in order to analyze the stability of the relative equilibrium. The case of finite frequencies and arbitrary modulation amplitudes is treated along with the case of high frequencies and small modulation amplitudes. In the former case, the parametric resonance domains are examined depending on the parameters of the system. In the latter case, the high-frequency vibration is shown to create effective surface tension, thus flattening the interface, and can suppress instability when the heavy fluid is over the light one. 相似文献
996.
The interface between cold gas sprayed zinc-based coatings and selected light weight alloy substrates (aluminium AA7022 and
magnesium AZ91) has been investigated by scanning and transmission electron microscopy in combination with energy-dispersive
X-ray spectroscopy. In both cases a non-uniform interfacial zone with a thickness of up to 10 microns is evident. It consists
of coating and substrate phases as well as an approximately 1 micron thick, partially whirled layer. For the AA7022 substrate
the interfacial layer contains nano and submicron sized crystallites of the binary MgZn2 phase (η) which are embedded in an aluminium solid solution matrix. In the case of AZ91 substrate two ternary phases, Mg5Zn2Al2 (φ) and Mg11Zn11Al6 (τ) with particle size smaller than 50 nm are evident. The formation of these phases during spraying cannot be explained
by diffusion process only, but a local melting is needed. Consequently, the assumption that the high kinetic energy of cold
gas sprayed particles causes an intensive mechanical mixing of coating and substrate material accompanied by a high local
temperature rise is proved. 相似文献
997.
LI Gang WANG Ke-Xiang ZHAO Ji-Jiu YUE Ke-Juan DAI Ming-Sui HUANG Yi-Ling JIANG Bo 《中国物理C(英文版)》2008,32(4)
A superconducting cryogenic system has been designed and deployed in the Beijing Electron-Positron Collider Upgrade Project(BEPCⅡ).The system consists of a Siemens PLC(ST-PLC,Programmable Logic Controller)for the compressor control,an Allen Bradley(AB)PLC for the cryogenic equipments,and the Experimental Physics and Industrial Control System(EPICS)that integrates the PLCs.The system fully automates the superconducting cryogenic control with process control,PID(Proportional-Integral-Differential)control loops,real-time data access and data storage,alarm handler and human machine interface.It is capable of automatic recovery as well.This paper describes the BEPCⅡ cryogenic control system,data communication between ST-PLC and EPICS Input/Output Controllers(IOCs),and the integration of the flow control,the low level interlock,the AB-PLC,and EPICS. 相似文献
998.
S. Kisin 《Polymer Degradation and Stability》2007,92(4):605-610
Creating oxygen containing moieties (hydroxyl or carbonyl) on polymer substrate surfaces is known to increase the adhesion strength of polymers to metals. However, we noticed adhesion increase with time even though no pre- or post-treatment of the polymer substrate was done. In the case of sputtered and galvanically strengthened copper coatings on acrylonitrile-butadiene-styrene polymer (ABS) substrate, the adhesion strength increased from approximately 6 J/m2 to 53 J/m2 during a 1008-h period. During this period structural and chemical changes of the polymer near the interface take place. Carbonyl functionalities developed on the ABS surface are most likely responsible for the large increase in the adhesion strength. Chemical changes of the polymer are probably a consequence of the galvanic deposition and a close contact of ABS with copper which is known to facilitate the oxidation of ABS. 相似文献
999.
Summary The problem of a hole at bimaterial interface is of practical importance in providing a good understanding of the debonding
phenomenon and for determining factors that affect the mechanical properties of composite elements of structures. The problem
of a point dislocation in bending bonded dissimilar semi-infinite plates with an elliptical hole at interface is tackled in
this paper. Based on the method of analytic continuation and the rational mapping function technique, the problem of obtaining
the stress functions in the upper and lower plates is decoupled, and reduced to two Riemann–Hilbert problems. The closed-form
solution is obtained. The stress distributions at the bimaterial interface, as well as the debonding at both vertices of the
elliptical hole are studied. The stress intensities of debonding are depicted for various parameters.
Received 16 March 2000; accepted for publication 12 July 2000 相似文献
1000.
Sabrina S. Hafiz Daniela Labadini Ryan Riddell Erich P. Wolff Marvin Xavierselvan Paul K. Huttunen Srivalleesha Mallidi Michelle Foster 《Particle & Particle Systems Characterization》2020,37(5):1900469
Eutectic gallium indium (EGaIn), a Ga-based liquid metal alloy holds great promise for designing next-generation core–shell nanoparticles (CSNs). A shearing-assisted ligand-stabilization method has shown promise as a synthetic method for these CSNs; however, determining the role of the ligand on stabilization demands an understanding of the surface chemistry of the ligand–nanoparticle interface. EGaIn CSNs are created and functionalized with aliphatic carboxylates of different chain length, allowing a fundamental investigation on ligand stabilization of EGaIn CSNs. Raman and diffuse reflectance Fourier transform spectroscopies (DRIFTS) confirm reaction of the ligand with the oxide shell of the EGaIn nanoparticles. Changing the length of the alkyl chain in the aliphatic carboxylates (C2–C18) may influence the size and structural stability of EGaIn CSNs, which is easily monitored using atomic force microscopy (AFM). No matter how large the carboxylate ligand, there is no obvious effect on the size of the EGaIn CSNs, except the particle size getting more uniform when coated with longer chain carboxylates. The AFM force–distance measurements are used to measure the stiffness of the carboxylate-coated EGaIn CSNs. In corroboration with DRIFTS analysis, the stiffness studies show that the alkyl chains undergo conformational changes upon compression. 相似文献