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251.
Creep of two Ni-AI alloys containing 4.8 and 7.0 wt pct Al was studied in the temperature range 873 to 1073 K and stress range
30 to 400 MPa. The former alloy represents the solid solution of aluminum in nickel, the latter a solid solution strengthened
by NI3AI particles.
As to its creep behavior the solid solution alloy belongs to the Class n of solid solu-tions,i.e. the creep controlling mechanism is the same as in pure nickel. From the analy-sis of an effective stress dependence of steady
state creep rate it follows that the mo-tion of jogged screw dislocations can be considered as the most probable creep control-ling
mechanism.
The apparent activation energy of creep in the two phase alloy increases with tempera-ture. This effect is caused by changes
in the volume fraction of second phase particles and by the onset of climb around particles at high temperatures. At lower
temperatures particles are cut by dislocation pairs. 相似文献
252.
K. Čulik H.A. Maurer Th. Ottmann K. Ruohonen A. Salomaa 《Theoretical computer science》1978,6(2):143-173
It is shown that if two PD0L forms F1 and F2 are form equivalent, i.e., generate the same family of languages, then the PD0L sequences E(F1) and E(F2) are isomorphic, provided one of the sequences contains a word of length greater than one. This result leads to a simple algorithm of deciding the form equivalence of two PD0L forms F1 and F2. Moreover, we obtain the rather surprising result that F1 and F2 are form equivalent if and only if they are sequence equivalent, i.e., generate the same family of PD0L sequences (excluding again the trivial case that F1 and F2 generate only words of length one). 相似文献
253.
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256.
Conductivity measurements on amorphous Ge films in the frequency range 20 Hz–26 GHz are described. Above 100 MHz the frequency dependence of the conductivity at room temperature satisfied the power law σ∝ωs with s=0.45-0.7. No saturation of the conductivity was observed. When the Ge films were doped with 0.1–1 at. % Sb the conductivity was frequency independent up to 26 GHz. A.c. hopping conduction seems to be compatible with the experimental results. 相似文献
257.
258.
Leona Buňková František Buňka Gabriela Mantlová Andrea Čablová Ivo Sedláček Pavel Švec Vendula Pachlová Stanislav Kráčmar 《Food microbiology》2010
The aim of the work was to describe the development of selected biogenic amines (histamine, tyramine, putrescine and cadaverine) in 4 layers of Dutch-type cheese (Edam-cheese) depending on 3 ripening/storage regimes during a 98-day period. Biogenic amines were analysed by means of ion-exchange chromatography. A further goal was to identify microbial sources of biogenic amines in the material analysed. Phenotype characterization and repetitive sequence-based PCR fingerprinting were used to identify the isolated bacteria. The highest content of tyramine, putrescine and cadaverine was determined in cheeses stored in a ripening cellar at a temperature of 10 °C during the whole observation period. Lower biogenic amines content was determined in samples which were moved into a cold storage device (5 °C) after 38 days of storage in a ripening cellar (10 °C). The lowest concentrations of biogenic amines were detected in cheeses which were moved into a cold storage device (5 °C) after 23 days of storage in a ripening cellar (10 °C). During the 98-day period, histamine was not detected in any of the regimes. Within the cheeses analysed, non-starter lactic acid bacteria Lactobacillus curvatus, Lactobacillus casei/paracasei and Lactobacillus plantarum were detected as the main producers of the biogenic amines tested. In starter bacteria Lactococcus lactis subsp. lactis and Lactococcus lactis subsp. cremoris the decarboxylase activity tested was not detected. 相似文献
259.
Vázquez-Araújo L Chambers E Adhikari K Carbonell-Barrachina ÁA 《Journal of food science》2010,75(7):S398-S404
The quality parameters of 1 commercial pomegranate juice mixed with 5 different concentrations of blueberry, blackberry, or raspberry juices were studied. The pH, total soluble solids content, titratable acidity, and total phenolic content were determined. To understand the aroma differences of the juices, solid phase microextraction-gas chromatography-mass spectrometry was used to determine the volatile compounds present in the mixtures. A consumer study also was carried out to relate consumer ratings to the instrumental data and to determine acceptance and possible modifications of the designed juices. Four juices received the highest scores in overall consumer liking: pomegranate/blueberry juice with 20% and 50% of blueberry, pomegranate/blackberry with 10% of blackberry, and pomegranate/raspberry with 10% of raspberry. The main characteristics in these juices were: a high maturity index (from 13.9 to 16.5), low acidity (0.79 to 1.09 g citric acid 100 per milliliter juice), and the presence of aromatic compounds typical in blueberries such as 6-methyl-5-hepten-2-one, α-terpineol, and E-nerol. The total phenolic content was significantly higher in the pomegranate/blackberry 90%/10% sample, raising around 3500 mg gallic acid equivalents per liter, and could be a positive determinant for consumers interested in purchasing healthful products. PRACTICAL APPLICATION: The data presented in this article will help the juice industry, in the United States and elsewhere, to understand the consumer's preferences for pomegranate blended juices. Pomegranate juices have high antioxidant content, which makes these juices more desirable for the health-conscious consumer of today. 相似文献
260.
E. Moyano-Ávila L. Orozco-Barbosa F. J. Quiles 《Journal of Signal Processing Systems》2009,55(1-3):267-279
In this paper, we introduce and evaluate the parallel implementations of two video sequences decorrelation algorithms having been developed based on the non-alternating three-dimensional wavelet transform (3D-WT) and the temporal-window method. The proposed algorithms have been proven to outperform the classic 3D-WT algorithm in terms of a better coding efficiency and lower computational requirements while enabling a lossless coding and a top-quality reconstruction: the two most highly relevant features to medical imaging applications. The parallel implementations of the algorithms are developed and tested on a shared memory system, a SGI Origin 3800 supercomputer, making use of a message-passing paradigm. We evaluate and analyze the performance of the implementations in terms of the response time and speed-up factor by varying the number of processors and various video coding parameters. The key point enabling the development of highly efficient implementations rely on a workload distribution strategy supplemented by the use of parallel I/O primitives, for better exploiting the inherent features of the application and computing platform. Two sets of I/O primitives are tested and evaluated: the ones provided by the C compiler and the ones belonging to the MPI/IO library. 相似文献