8,325 research outputs found
Influence of some metals on the rate of corrosion and deposition of titanium in molten salt baths
2. The purpose of this investigation. The substances obtained by corrosion of titanium in fused salts, if leached with water and dried, are composed of three kinds of products, namely of black, gray and yellowish ones. The black product was identified by X-ray diffraction as titanium-oxygen alloy with 9-10% by weight oxygen which later was used as coating material instead of the titanium sheet for deposition experiments described previously. The yellowish product was identified as rutile. The grayish product was also rutile but containing some titanium powder. Of these three products only the black one possessed the ability to deposit itself upon other metals, forming a titanium diffusion layer. The absolute amount of the corrosion products increased with time of beating and temperature. Since the thickness of titanium diffusion layers depends on the concentration of pyrosols, actually dispersions, in the fused salt the first aim of this research was to collect more information about these dispersions. Thus, the corrosion rates of titanium in fused salts in presence of other metal chlorides were studied in detail because it was suspected that some metal chlorides might increase these rates. The second aim was to investigate the effects on the formation of titanium coatings by precoating the base metal with other metals. Corrosion tests, to check the quality of the coatings were also made --Introduction, pages 3-4
Asymmetric sequential Landau-Zener dynamics of Bose condensed atoms in a cavity
We explore the asymmetric sequential Landau-Zener (LZ) dynamics in an
ensemble of interacting Bose condensed two-level atoms coupled with a cavity
field. Assuming the couplings between all atoms and the cavity field are
identical, the interplay between atom-atom interaction and detuning may lead to
a series of LZ transitions. Unlike the conventional sequential LZ transitions,
which are symmetric to the zero detuning, the LZ transitions of Bose condensed
atoms in a cavity field are asymmetric and sensitively depend on the photon
number distribution of the cavity. In LZ processes involving single excitation
numbers, both the variance of the relative atom number and the step slope of
the sequential population ladder are asymmetric, and the asymmetry become more
significant for smaller excitation numbers. Furthermore, in LZ processes
involving multiple excitation numbers, there may appear asymmetric population
ladders with decreasing step heights. During a dynamical LZ process, due to the
atom-cavity coupling, the cavity field shows dynamical collapse and revivals.
In comparison with the symmetric LZ transitions in a classical field, the
asymmetric LZ transitions in a cavity field originate from the
photon-number-dependent Rabi frequency. The asymmetric sequential LZ dynamics
of Bose condensed atoms in a cavity field may open up a new way to explore the
fundamental many-body physics in coupled atom-photon systems.Comment: 14 pages, 6 figure
Velocity distribution and 3D turbulence characteristic analysis for flow over water-worked rough bed
YesTo reproduce the natural flow topography in a laboratory environment, it is crucial to recapture its bed condition in order to ensure the accurate representation. Water-worked bed represents a state-of-the-art experimentally formed bed to imitate the natural-formed channel in most rivers or natural streams. Recently, this technique has been intensively studied through experimental and computational approaches; however, its actual influence towards the near-bed flow as compared to experimentally prepared rough bed in well-packed bedform order are still yet to be investigated deeply. This experimental study systematically investigated and compared the differences in velocity distribution and three-dimensional (3D) turbulence characteristics, including turbulence intensities and Reynolds stresses, between uniform smooth bed, laboratory-prepared rough bed and water-worked bed open channel flows. The flow comparisons were concentrated at near-bed region where clear flow behaviour change can be observed. Through these comparisons, the study inspected the characteristics of water-worked bedform thoroughly, in order to inform future experimental research that tries to reproduce natural stream behaviours.the Major State Basic Research Development Grant No. 2013CB036402 from Tsinghua University. The support from the Major State Basic Research Development Program (973 program) of China is also greatly appreciated. We also acknowledge the National Key Research and Development Project from the Ministry of Science and Technology during the Thirteenth Five-year Plan Period (Grant No. 2017YFC0403600) and the Science and Technology Projects State Grid Corporation of China (Grant No. 52283014000T)
The effect of hidden color channels on nucleon-nucleon interaction in quark model
In the framework of constituent quark model, the effect of hidden color
channels on the nucleon-nucleon () interaction is studied. By adjusting the
color confinement strength between the hidden color channels and color singlet
channels and/or between the hidden color channels and hidden color channels,
the experimental data of to partial-wave phase shifts of
scattering can be fitted well. The results show that the hidden color channel
coupling might be important in producing the intermediate-range attraction of
interaction. The deuteron properties and dibaryon candidates have also
been studied with this model.Comment: 11 pages, 9 figure
Object Discovery From a Single Unlabeled Image by Mining Frequent Itemset With Multi-scale Features
TThe goal of our work is to discover dominant objects in a very general
setting where only a single unlabeled image is given. This is far more
challenge than typical co-localization or weakly-supervised localization tasks.
To tackle this problem, we propose a simple but effective pattern mining-based
method, called Object Location Mining (OLM), which exploits the advantages of
data mining and feature representation of pre-trained convolutional neural
networks (CNNs). Specifically, we first convert the feature maps from a
pre-trained CNN model into a set of transactions, and then discovers frequent
patterns from transaction database through pattern mining techniques. We
observe that those discovered patterns, i.e., co-occurrence highlighted
regions, typically hold appearance and spatial consistency. Motivated by this
observation, we can easily discover and localize possible objects by merging
relevant meaningful patterns. Extensive experiments on a variety of benchmarks
demonstrate that OLM achieves competitive localization performance compared
with the state-of-the-art methods. We also evaluate our approach compared with
unsupervised saliency detection methods and achieves competitive results on
seven benchmark datasets. Moreover, we conduct experiments on fine-grained
classification to show that our proposed method can locate the entire object
and parts accurately, which can benefit to improving the classification results
significantly
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