Summary This paper deals with the two-dimensional static punch problems in the presence of friction for a periodically layered half-space. Within the framework of the homogenized model of linear elasticity with microlocal parameters [8–11] the exact solutions of the considered problems are obtained. The case of the indentation of the composite body by a rigid rectangular punch has been discussed in detail.
Ebene Kontaktprobleme für ein periodisches elastisches Zweischichten-Komposit
Übersicht In dieser Arbeit wird das zweidimensionale statische Stempelproblem mit Reibung für einen periodisch geschichteten Halbraum betrachtet. Im Rahmen eines Homogenisierungsmodells der linearen Elastizitätstheorie mit mikropolaren Parametern werden die exakten Lösungen der betrachteten Probleme gewonnen. Im Detail wird das Eindringen eines rechteckigen starren Stempels behandelt.
The crystal structures, solid-state infrared patterns, and thermal properties of two polymorphs of 4-nitrosalicylanilide are presented. In both polymorphs, intramolecular hydrogen bonds are found between the phenol oxygen and the amide proton, and intermolecular hydrogen bonds are found between the amide carbonyl oxygen and the phenol proton. These hydrogen bond patterns are compared to those found in other known salicylamide derivatives and an analysis is given of the factors contributing to preferences for intra- or intermolecular hydrogen bonds in these structures. Crystal data: polymorph, orthorhombic,Pbca,a=11.003(4),b=27.959(7),c=7.622(5) Å,Z=4,V=2345(3) Å3, andR=0.038 (1351 reflections); polymorph, monoclinic,P21/a,a=28.36(1),b=11.64(1),c=7.293(8) Å,=90.68(6)°,Z=8,V=2408 Å3, andR=0.043 (2425 reflections). 相似文献
Creep resistance investigations of the Al-40 wt % Zn alloy at room temperature have been performed and revealed some creep compliance. Additions of Cu and Si decrease considerably the preliminary creep compliance in the alloy which then turn to be dimensionally stable and resistant to creep. Tensile test investigations performed at different deformation rates have not revealed the existance of the superplastic deformation mechanism.Presented at the 4th International Symposium on Plasticity of Metals and Alloys, September 711, 1987, Srni, Czechoslovakia. 相似文献
Motivated by the operator formulation of conformal field theory on Riemann surfaces, we study the properties of the infinite dimensional group of local biholomorphic transformations (conformal reparametrizations) of 1 and develop elements of its representation theory. 相似文献
Ion-selective electrode with cellulose triacetate membrane containing nonactin is employed for the potentiometric detection of ammonia produced in biocatalytic reaction in flow-injection system with enzyme reactor. The elimination of interferences occurring in the presence of alkali metal ions was achieved by covering a nonactin membrane with outer hydrophobic gas permeable membrane. The obtained flow-injection response to ammonia indicates a possibility of ammonia determination down to 10 microM ammonia. In the flow-injection system for urea determination 200 microl of 10-fold diluted blood serum sample was injected into carrier stream of distilled water merged with TRIS buffer, passed through the urease flow-through reactor and then after merging with NaOH stream delivered to the detector. It was found in several series of natural blood serum samples, that the correction for endogenous ammonia in such a determination is not indispensable. 相似文献
Comparison of Lyocell, modal and viscose fibers was performed by means of differential scanning calorimetry, thermogravimetry
and scanning electron microscopy. Thermal analysis was performed in air atmosphere. Samples were mercerized (21.3 g 100 mL-1)
or submitted to solar radiation (seven months). Solar degraded samples presents a higher thermal stability and are initially
less degraded. Furthermore, Lyocell fiber is the most stable under thermal degradation conditions. Heating produces a reduction
of the fiber diameter (about 50%).
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
Chiral α,ω-diesters react under high-pressure conditions (10 kbar) with α,ω-diamines to give chiral cyclic tetraamides of C2-symmetry. The complexation properties of tetraamides towards alkali metal cations (Li+, Na+, K+, Rb+ and Cs+) were estimated on the basis of ESI-MS spectra. 相似文献
A method is presented for the selective determination of the volatile selenium species dimethylselenide and dimethyldiselenide, using a commercially available purge-and-trap injection system coupled to capillary gas chromatography-microwave induced plasma-atomic emission spectrometry. The efficiency of the purging step was evaluated and the parameters affecting the purge and trap processes were optimized. The method was applied to the determination of volatile selenium compounds in lake water. Relative detection limits of 2ng/l for dimethylselenide and dimethyldiselenide, corresponding to an absolute detection limit of 10 pg, were achieved. 相似文献
In this paper, several methods of hydrophobization of cotton fabrics using the thio-ene click reaction were compared. Durable, superhydrophobic textiles were obtained in an easy way. Various variants of functionalized silsesquioxanes were used for the hydrophobization of fabrics. The synthesis of bifunctional silsesquioxanes (RSiMe2O)4(ViSiMe2O)4Si8O12 and (RSiMe2O)4(R’SiMe2O)4Si8O12 were performed via hydrothiolation of silsesquioxane derivative (ViSiMe2O)8Si8O12. Alkoxysilyl, alkyl and fluoroalkyl moieties were introduced as functional groups. Samples were prepared using four methods, differing in the modification method and the number of stages. During the research, fabrics were modified via (a) the dip-coating process, (b) carrying out thiol-ene click reactions directly on the surface of the fabric and (c) using both of these methods. The hydrophobicity of the fabric was evaluated by measuring the Water contact angle (WCA). The obtained samples were also examined using infrared analysis (FT-IR), Scanning electron microscope (SEM), and Elemental analysis (SEM–EDS). All analyses were performed before and after the washing process in order to verify the stability of the performed modifications.