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31.
Timber bridges – Long term monitoring results of moisture diffusion in the load carrying cross‐sections Timber road bridges have been built worldwide for centuries. The high performance of wood is approved through many constructions. However, there are still doubts about using wood by the planning engineer, which reduce the number of realized projects. The moisture induced stresses in cross‐sections according to the varied ambient climate are mainly investigated under laboratory conditions. The results show that the moisture content changes differently over the cross‐section and leads to moisture induced stresses. The discussion about methods for the assessment of the moisture induced stresses in timber bridge cross‐ections is continuing. Results observed in the long term monitoring of seven timber bridges provide first guidelines for practitioners. For all constructions, the moisture content was measured regarding the ambient micro climate. As result, the influences according to the ambient micro climate are not insignificant. Positive is that the directly measured moisture content is less compared to the equilibrium moisture content calculated from the data of a close by meteorological station. The analysis of the moisture gradient over the cross‐section allows the definition of an active or passive zone. 相似文献
32.
A.S. Budiman C.S. Hau-Riege W.C. Baek C. Lor A. Huang H.S. Kim G. Neubauer J. Pak P.R. Besser W.D. Nix 《Journal of Electronic Materials》2010,39(11):2483-2488
While Black’s equation for electromigration (EM) in interconnects with n = 1 is rigorously based on the principles of electrotransport, n > 1 is more commonly observed empirically. This deviation is usually attributed to Joule heating. An alternative explanation
is suggested by the recent discovery of EM plasticity. To examine this possibility, we have retested samples that had been
previously subjected to a predamaging phase of high temperature and current densities to determine whether the loss of median
time to failure (MTF) is retained. We find that the predamaged samples exhibit MTFs that are permanently reduced, which is
a characteristic of EM plasticity. 相似文献
33.
Dietary rapeseed/canola‐oil supplementation reduces serum lipids and liver enzymes and alters postprandial inflammatory responses in adipose tissue compared to olive‐oil supplementation in obese men 下载免费PDF全文
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Dr. Anne Hänchen Dr. Saskia Rausch Benjamin Landmann Dr. Luigi Toti Antje Nusser Prof. Dr. Roderich D. Süssmuth 《Chembiochem : a European journal of chemical biology》2013,14(5):625-632
The antibiotic feglymycin is a linear 13‐mer peptide synthesized by the bacterium Streptomyces sp. DSM 11171. It mainly consists of the nonproteinogenic amino acids 4‐hydroxyphenylglycine and 3,5‐dihydroxyphenylglycine. An alanine scan of feglymycin was performed by solution‐phase peptide synthesis in order to assess the significance of individual amino acid side chains for biological activity. Hence, 13 peptides were synthesized from di‐ and tripeptide building blocks, and subsequently tested for antibacterial activity against Staphylococcus aureus strains. Furthermore we tested the inhibition of peptidoglycan biosynthesis enzymes MurA and MurC, which are inhibited by feglymycin. Whereas the antibacterial activity is significantly based on the three amino acids D ‐Hpg1, L ‐Hpg5, and L ‐Phe12, the inhibitory activity against MurA and MurC depends mainly on L ‐Asp13. The difference in the position dependence for antibacterial activity and enzyme inhibition suggests multiple molecular targets in the modes of action of feglymycin. 相似文献
36.
A standard problem in intensity modulated radiation therapy is the representation of a given intensity matrix, i.e. a matrix
of nonnegative integers, as a nonnegative linear combination of special 0-1-matrices, called segments. These segments can
be practically realized by multileaf collimators. One important aim is the minimization of the sum of the coefficients of
the linear combination, i.e. the delivery time. In this article, we study the question how much the delivery time can be reduced
if some small deviation from the given intensity matrix is allowed. We characterize the optimal solutions for one-row matrices
and show that the approximation can be carried out in an iterative way. The structural characterization yields a fast algorithm
that minimizes the delivery time and then also the deviation. Moreover, algorithms for the general case together with numerical
results are presented. 相似文献
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Jürgen Rödel Alain B.N. Kounga Marion Weissenberger-Eibl Daniel Koch Antje Bierwisch Wolfgang Rossner Michael J. Hoffmann Robert Danzer Gerhard Schneider 《Journal of the European Ceramic Society》2009,29(9):1549-1560
A roadmap for advanced ceramics for the period from 2010 to 2025 has been developed to provide guidelines for future investments for policy makers, scientists and industry alike. Based on questionnaires, interviews and a final workshop with well-balanced participation of members from industry and academia three roadmaps on application fields and two roadmaps on scientific areas have been developed and contrasted. The three application fields selected are: (i) electronics, information and communication; (ii) energy and environment; (iii) mechanical engineering and the two scientific fields are: (a) structural and functional properties; (b) process technology. Within these fields the tremendous growth opportunities for ceramics as an enabling technology are highlighted and manifold suggestions for future development are provided. 相似文献
39.
Patrizio Neff Antje Sydow Christian Wieners 《International journal for numerical methods in engineering》2009,77(3):414-436
We investigate a representative model of continuum infinitesimal gradient plasticity. The formulation is an extension of classical rate‐independent infinitesimal plasticity based on the additive decomposition of the symmetric strain tensor into elastic and plastic parts. It is assumed that dislocation processes contribute to the storage of energy in the material whereby the curl of the plastic distortion appears in the thermodynamic potential and leads to an additional nonlocal backstress tensor. The formulation is cast into a numerical framework by a saddle point approximation of the corresponding minimization problem in each incremental loading step. This allows one to reformulate the (nonlocal) dissipation inequality to a point‐wise flow rule and yields a solution scheme, which is a direct extension of the standard approach in classical plasticity. Our numerical results show the regularizing effects of the additional physically motivated terms. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
40.
The chemical composition of alinite was investigated in the system CaO--- SiO2---Al2O3---MgO---CaCl2. Solid solution was observed. The formula should be written as Ca10Mg1−x/2□x/2[(SiO4)3+x(AlO4)1−x/O2Cl] with 0.352 (chloride not combined with alinite) which is present after synthesis influences the hydration. Calorimetric and SEM investigations lead to the following equation: . 相似文献