[en] Numerical reproducibility and stability of large scale scientific simulations, especially climate modeling, on distributed memory parallel computers are becoming critical issues. In particular, global summation of distributed arrays is most susceptible to rounding errors, and their propagation and accumulation cause uncertainty in final simulation results. We analyzed several accurate summation methods and found that two methods are particularly effective to improve (ensure) reproducibility and stability - Kahan's self-compensated summation and Bailey's double-double precision summation. We provide an MPI operator MPI(underscore)SUMMDD to work with MPI collective operations to ensure a scalable implementation on a large number of processors. The final methods are particularly simple to adopt in practical codes

[en] The cation-mixed layered Mn_xFe_1-xPS₃ (0≤x≤1) compounds are synthesized from the corresponding elements at 700 deg. C. These compounds are characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), magnetic susceptibility measurements and Moessbauer spectroscopy. The magnetic measurements show that the antiferromagnetic interaction is retained in the mixed phases, but the magnetic order is weakened due to manganese ions and iron ions are diluted by each other in the mixed phases. Moessbauer spectra show that Fe²⁺ ions and Fe⁰⁺ are co-existent in the mixed phases when 0.1≤x≤0.6. The manganese ions and iron ions form their zigzagging chains, respectively, and a few of the same chains form a group, while manganese ion chain groups and iron ion chain groups are diluted by each other. In the interface between different groups, strong distortions take place in the FeS₆ and MnS₆ octahedra, and some electron transformations occur from the 3d band electrons in manganese ions to 4s or 3d bands of the iron ions

[en] ⁵⁷Fe Moessbauer spectroscopy, X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), and differential thermal analysis (DTA) have been used to investigate the thermal decomposition behavior of iron oxychloride. Upon heating of FeOCl in air for a long time, the compound is decomposed around 376 deg. C and turns into Fe₂O₃ and FeCl₃

[en] Two 115 in. long copper ultrahigh vacuum (UHV) chambers for the Cornell Electron Storage Ring (CESR) interaction region were fabricated. These chambers are a part of the phase-III upgrade project for the CESR storage ring. They incorporate several novel features including a remotely engaging differentially pumped Viton O ring sealed UHV flange, two rf shielded bellows joints, and inner stepped masking for synchrotron radiation. The fabrication of these chambers incorporates multistage electron beam welding to maintain the strict tolerance required for installation through superconducting and permanent quadrupole magnets. Before final welding, a series of electron beam welding setup tests were done to work out a welding procedure for optimizing the welding parameters and avoiding contamination in the weld zone. In this article we will describe the design, fabrication, welding, leak checking, and final UHV performance testing of these chambers

[en] Arbitrary sparse array could extend the array aperture. And the position of sparse array elements has little constraint. But, the manifold ambiguity of sparse array will cause ambiguity angle estimation. In order to avoid manifold ambiguity in Multiple Input Multiple Output (MIMO) radar with sparse array, a new solving ambiguity method is proposed based on sliding the array. By employing reduced multiple signal classical algorithm(RE-MUSIC), the true direction of departure (DOD) and direction of arrival (DOA) are obtained. The main idea of the proposed method is that get DODs and DOAs separately by RE-MUSIC algorithm. When transmitter exists the ambiguity, we compare the RE-MUSIC spectrum of pre-sliding transmitting array with the RE-MUSIC spectrum of post-sliding transmitting array to obtain the true DODs. Then we obtain the true DOAs by the RE-MUSIC spectrum of receiving array. It is similar to receiver exists the ambiguity. Simulation results verify the validity of the proposed method. (paper)

[en] Based on the variational principle, a continuum theory of surface elasticity and new boundary conditions for quasicrystals is proposed. The effect of the residual surface stress on a decagonal quasicrystal that is weakened by a nanoscale elliptical hole is considered. The explicit expressions for the hoop stress along the edge of the hole are obtained using the Stroh formalism. The results show that the residual surface stress and the shape of the hole have a significant effect on the elastic state around the hole. (condensed matter: structural, mechanical, and thermal properties)

[en] The Long Baseline Neutrino Experiment (LBNE) will utilize a neutrino beamline facility located at Fermilab. The facility is designed to aim a beam of neutrinos toward a detector placed at the Deep Underground Science and Engineering Laboratory (DUSEL) in South Dakota. The neutrinos are produced in a three-step process. First, protons from the Main Injector hit a solid target and produce mesons. Then, the charged mesons are focused by a set of focusing horns into the decay pipe, towards the far detector. Finally, the mesons that enter the decay pipe decay into neutrinos. The parameters of the facility were determined by an amalgam of the physics goals, the Monte Carlo modeling of the facility, and the experience gained by operating the NuMI facility at Fermilab. The initial beam power is expected to be ∼700 kW, however some of the parameters were chosen to be able to deal with a beam power of 2.3 MW.

[en] We consider the Q − Φ criticality of RN-AdS black hole in four-dimensional spacetime. Especially, by employing the fractional derivative we reanalyze the order of phase transition at the critical point. By means of this fine-grained classification of phase transition, it is found that at the critical point it is a 4/3-order, but not the second-order phase transition. This result is the same as that obtained in a previous work on the basis of P − V criticality. (paper)

[en] The electromagnetic properties of unidirectional SiC fibre composites can be efficiently tailored by adjusting the properties of the composite’s constituents making these composites potential microwave absorbers. In this study, the microwave absorbing properties of unidirectional SiC fibre composites were investigated based on the electromagnetic properties of the constituents at frequencies ranging from 8 to 18 GHz. The composite was composed of two types of SiC fibres that individually exhibit relatively high and low electrical conductivity. The matrix together with the low-conductivity SiC fibres were characterized by effective permittivity and conductivity which provided a theoretical calculation of the microwave reflectivity. The theoretical calculation was based on formulas about anisotropic unidirectional composites and was compared to the results obtained from numerical simulations. There was good agreement in the results obtained from both methods. It was found that the intensity of microwave absorption of the composite was dependent primarily on the properties of the high-conductivity SiC fibres. The absorption band appeared to be dependent on the effective permittivity of the matrix and the low-conductivity SiC fibres and the conductivity of the high-conductivity SiC fibres. (paper)

[en] The electronic configuration of antimony in Ba(Sb_0.5In_0.5)O₃ prepared by hydrothermal synthesis method has been studied by XRD and Moessbauer spectroscopy. Based on the evaluation of Moessbauer spectroscopy and considering also the XRD result, the single-phase perovskite crystals are obtained, the covalent bonding of Sb(V) to the neighbouring oxygen reflects on some hybridized orbital behaviour. (authors)