[en] We study the non-equilibrium quantum dynamics of attractive Fermi gases in one- and two-dimensional optical lattice. We use the dynamic Bogoliubov–de Gennes (DBdG) method and time-evolving block decimation (TEBD) to investigate the expansion dynamics, which can be implemented by suddenly removing the harmonic trap. The evolutions of density and superfluid order parameters have been calculated. We find that for the noninteracting case, the expansion rate is linear with hopping amplitude, which is a ballistic expansion result. And the interaction damps the expansion rate exponentially both in one and two dimensions and makes it deviate from the ballistic expansion. - Highlights: • We use DBdG method and TEBD to investigate the expansion dynamics in optical lattice. • We calculate the evolution of density and superfluid order parameters. • We find a ballistic expansion result for non-interacting case. • We find interaction damps the expansion rate exponentially

[en] In this article we present an exploratory lattice QCD calculation of the neutrinoless double beta decay $\mathrm{\pi <!--\; ??\; -->}\mathrm{\pi <!--\; ??\; -->}\to <!--\; ???\; -->ee$. Under the mechanism of light-neutrino exchange, the decay amplitude involves significant long-distance contributions. The calculation reported here, with pion masses $m_{\mathrm{\pi <!--\; ??\; -->}}=420$ and 140 MeV, demonstrates that the decay amplitude can be computed from first principles using lattice methods. At unphysical and physical pion masses, we obtain that amplitudes are $24\mathrm{\%<!--\; \%\; -->}$ and $9\mathrm{\%<!--\; \%\; -->}$ smaller than the predication from leading order chiral perturbation theory. Our findings provide the lattice QCD inputs and constraints for effective field theory. A follow-on calculation with fully controlled systematic errors will be possible with adequate computational resources.

[en] The analysis, optimization, design and operation of cascades for isotope separation involve computations of cascades. In analytical analysis of cascades, using virtual components is a very useful analysis method. For complicated cases of cascades, numerical analysis has to be employed. However, bound up to the conventional idea that the concentration of a virtual component should be vanishingly small, virtual component is not yet applied to numerical computations. Here a method of introducing the method of using virtual components to numerical computations is elucidated, and its application to a few types of cascades is explained and tested by means of numerical experiments. The results show that the concentration of a virtual component is not restrained at all by the 'vanishingly small' idea. For the same requirements on cascades, the cascades obtained do not depend on the concentrations of virtual components. (authors)

[en] Fracture characteristics of a TIG welded joint and heat-treated materials of JN1, which is an austenitic stainless steel recently developed for use as a cryogenic structural material, were evaluated by the small punch (SP) testing method using miniaturized specimens at 77 K and 4 K. The area under the load-displacement curve up to the maximum load was defined as the SP energy to evaluate the fracture characteristics of the materials in SP tests. Fracture surfaces were also observed using a scanning electron microscope. Solution-treated JN1 steel showed ductile fracture behavior with a high SP energy value even at 4 K, and serrations were observed in the load-displacement curve at 4 K. In the weld metal and fusion line specimens of the TIG welded joint, serrations also occurred at 4 K, but the fusion line specimens showed lower SP energy values than weld metal and solution-treated JN1 steel at 77 K and 4 K. In addition, the fusion line specimens showed pop-in behavior at 4 K, that is, cracks approximately 0.1-1mm long were induced by pop-in in the vicinity of the fusion line at the early stage of loading. JN1 materials heat-treated under the conditions of 650degC-5h and 700degC-1h showed similar fracture characteristics to those of the fusion line specimens at 77 K and 4 K except for the cracks induced by pop-in. With increasing temperature and time of heat treatment, SP energy decreased significantly, and the fracture surface showed a transition from ductile dimple to brittle intergranular cracking. It is shown that the SP testing method is useful for evaluating the fracture behaviors of microscopic regions such as the fusion lines of welds at cryogenic temperatures. (author)

[en] Q235b carbon steel, main material of early alkaline radioactive liquid waste tank, can be contaminated by ⁹⁰Sr and ¹³⁷Cs. In this work, batch contamination experiments were conducted to simulate contamination of steel. The results indicated that Fe₃O₄, main corrosion product, fell off to form sludges. Furthermore, Sr existed mainly in form of SrCO₃ in oxide layer and sludge, and the corrosion made Sr enter into corrosion defects. While Cs was more limited to surface, mainly in form of CsNO₃ on the surface of oxide layer and sludge. The findings of this work will facilitate the development of efficient decontamination techniques. (author)

[en] A MWPC readout system is designed for a high trigger rate fixed target experiment E871 in Fermilib in US. The system is pipeline structured which includes signal latch, derandomize FIFO, encoder and buffers, and has the dead time less then 0.47 μs. The system is composed of two daisy-chained crates in which there are multiple FEM modules and their interface FEMI. 128 channels of the wire signals are received and processed by each FEM. Fore reducing the readout time, the daisy-chain circuit is used readout the relatively sparse data. The operations are accomplished by the hardware. A series of events are processed in different stages at the same time and is continuously passed through the MWPC readout system. The system has been fully tested. 10⁹ fake events were received and processed without fault at 250 kHz trigger rate

[en] Geological surface modeling is typically based on seismic data, well data, and models of regional geology. However, structural interpretation of these data is error-prone, especially in the absence of structural morphology information, Existing geological surface models suffer from high levels of uncertainty, which exposes oil and gas exploration and development to additional risk. In this paper, we achieve a reconstruction of the uncertainties associated with a geological surface using chance-constrained programming based on multi-source data. We also quantified the uncertainty of the modeling data and added a disturbance term to the objective function. Finally, we verified the applicability of the method using both synthetic and real fault data. We found that the reconstructed geological models met geological rules and reduced the reconstruction uncertainty.

[en] Grouping objects into clusters based on the similarities or weights between them is one of the most important problems in science and engineering. In this work, by extending message-passing algorithms and spectral algorithms proposed for an unweighted community detection problem, we develop a non-parametric method based on statistical physics, by mapping the problem to the Potts model at the critical temperature of spin-glass transition and applying belief propagation to solve the marginals corresponding to the Boltzmann distribution. Our algorithm is robust to over-fitting and gives a principled way to determine whether there are significant clusters in the data and how many clusters there are. We apply our method to different clustering tasks. In the community detection problem in weighted and directed networks, we show that our algorithm significantly outperforms existing algorithms. In the clustering problem, where the data were generated by mixture models in the sparse regime, we show that our method works all the way down to the theoretical limit of detectability and gives accuracy very close to that of the optimal Bayesian inference. In the semi-supervised clustering problem, our method only needs several labels to work perfectly in classic datasets. Finally, we further develop Thouless–Anderson–Palmer equations which heavily reduce the computation complexity in dense networks but give almost the same performance as belief propagation. (paper: interdisciplinary statistical mechanics)

[en] A thermal emitter composed of a frequency-selective surface metamaterial layer and a hexagonal boron nitride-encapsulated graphene filament is demonstrated. The broadband thermal emission of the metamaterial (consisting of ring resonators) was tailored into two discrete bands, and the measured reflection and emission spectra agreed well with the simulation results. The high modulation frequencies that can be obtained in these devices, coupled with their operation in air, confirm their feasibility for use in applications such as gas sensing. .

[en] Although there are many primary carbides in the cutting edge of knives made of high-carbon martensitic steel, the effect of primary carbides on the sharpness of knives has not been clarified. In this paper, the evolution of primary carbides during the production process of 8Cr13MoV steel was presented. The effect of size and amount of primary carbides on the sharpness of knives was studied via employing rolling forging and diffusion annealing process, respectively. Results indicated that primary carbides easily fell off from cutting edge during cutting process, which would decrease the wear resistance of knives. The refinement of primary carbides could not only improve the wear resistance of cutting edge, but also weaken the fluctuation of sharpness during the service process of knives. By decreasing the amount of primary carbides, the wear resistance of knives would increase effectively, which improved the cutting performance effectively. Reducing the amount of primary carbides and refining the primary carbides in cutting edge were both effective ways to improve the sharpness of knives.