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71.
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AN IMPROVED ARC-LENGTH METHOD AND APPLICATION IN THE POST-BUCKLING ANALYSIS FOR COMPOSITE STRUCTURES
Based on the conventional arc- length method, an improved arc- length method with high-efficiency is proposed. The weighted modifications with respect to the variation of structural stiffness and extra-interpolation modification by using the information of known equilibrium points are introduced to improve the incremental arc- length . An approximate expansion method for the accumulated and expected arc-length is used to ensure the convergence at given load levels in large range of applications. Numerical results show that the improved arc-length method has well adaptability and higher efficiency in the post-buckling analysis of plates and sheik structures for tracing whole load-deflection path and obtaining the convergence values at any specified load levels. 相似文献
74.
IntroductionSincethespecialsuperiorityofartificialneuralnetworkstechnologyinvariousengineeringtechniquesfields,suchasoptimization ,associativememories,patternrecognition ,signalprocessingandautomaticcontrol,therehasbeenincreasinginterestintheinvestigati… 相似文献
75.
Walter Eberhard Steger 《Macromolecular Symposia》1988,18(1):77-92
The mechanism of RAMAN scattering depends on molecular polarizability changes and therefore this method is especially useful for the study of non-polar bonds. This is shown by reviewing some analytical applications. Knowledge on polymer structure was especially promoted by studies of the lowest-frequency bending modes, of correlation splittings in case of crystallinity, and by measurements on depolarization of the laser light. RAMAN spectroscopy has possibilities for in-situ and multi-method measurements. Newer developments serving the polymer sciences are surface enhanced RAMAN scattering and the RAMAN spectroscopy of electroconducting polymers. 相似文献
76.
Eberhard Neumann Elvira Boldt Barbara Rauer Hendrik Wolf Hai Won Chang 《Macromolecular Symposia》1988,17(1):1-16
The nicotinic acetylcholine receptor (nAcChR) of the electric organ of Torpedo californica fish exhibits a pronounced hysteresis loop in the high affinity binding of the neurotransmitter acetylcholine (AcCh). When increasing amounts of AcCh are added (pulse mode) an extremely long-lived, metastable conformer distribution is obtained (lower hysteresis branch) between low affinity AcCh binding states (Rl) and high (Rh) and very high (Rvh) affinity states. Dialysis conditions always lead to the equilibrium binding curve (upper hysteresis branch; K̄A = 5 × 10−9M, 4°C; one A bound to the R-monomer of Mr ≈ 290 000). Cyclic, pulse mode addition and dilution of AcCh results in scanning loops within the main hysteresis. The kinetic analysis of the changes in free and bound AcCh during the open-system conditions of dialysis, that releases the metastability, shows that the AcCh (A) binding proceeds along an induced-fit pathway according to A+Rh ⇋ ARn ⇋ ARvh. The rate constant of the step ARh → ARvh is k2 = 6 × 10−3s−1 and that of the reverse step is k−2 = 3 × 10−4s−1. Direct binding of A to free Rvh can be excluded. Therefore, the state Rvh does not preexist, it is induced and only stable, as ARvh, by bound AcCh. The metastability can be described in terms of long-lived ARvh ·R1 hybrid dimers. Physiologically, the metastable hybrid may be viewed as a saving device: the functionally important, channel-active R1 conformer is, at low AcCh-concentrations [A] < 1μM, prevented to convert to the desensitized states Rh and ARvh. Furtheron, AcCh enhances the phosphorylation of phosphatidyl inositol and the auto-phosphorylation of the receptor. If the AcCh binding hysteresis causes a phosphorylation hysteresis the desensitized nAcChR may serve as a memory molecule of the transsynaptic information signalling of the neurotransmission. 相似文献
77.
Eberhard H. Lehmann Werner Wagner 《Applied Physics A: Materials Science & Processing》2010,99(3):627-634
Neutron imaging as a method for non-destructive studies takes advantage of the alternative contrast mechanism of neutrons
compared to X-rays: most of the light elements feature high contrast, whereas heavy elements are relatively transparent to
neutrons. In the previous decade, the neutron imaging technique has made substantial progress in well-tailored and well-equipped
beam lines, in improvements of the image recording quality and efficiency by new and modern imaging techniques, and in modern
image processing tools. 相似文献
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80.
Eberhard Siebert 《Probability Theory and Related Fields》1979,46(3):247-258
Summary In the theory of functional analytic comparison of statistical experiments (started by L. LeCam) one can characterize equivalence classes of experiments by conical measures (in the sense of G. Choquet). We begin with a short proof of the (known) fact that any conical measure with normed resultant belongs to an experiment class. Then we are concerned with the special case of dominated experiments which are characterized by the extendability of their conical measures to finite concrete measures. These results are in close connection with a paper of E.N. Torgersen (Mixtures and products of dominated experiments. Ann. Statist. 5, 44–64 (1977)).After this we study class properties of experiments which are expressible in terms of their conical measures. Simple examples are domination, existence of bounded densities and compactness. It follows the investigation of a more profound class property which we call extremality and which generalizes the concept of an experiment with a sufficient and boundedly complete subalgebra. Finally we prove that the extreme points of the compact convex set of conical measures with normed resultant are just the conical measures of the extremal experiments. 相似文献