[en] In this work the authors study the multiphase flow soft-sensing problem based on a previously established framework. There are three functional modules in this framework, namely, a transient well flow model that describes the response of certain physical variables in a well, for instance, temperature, velocity and pressure, to the flow rates entering and leaving the well zones; a Markov jump process that is designed to capture the potential abrupt changes in the flow rates; and an estimation method that is adopted to estimate the underlying flow rates based on the measurements from the physical sensors installed in the well. In the previous studies, the variances of the flow rates in the Markov jump process are chosen manually. To fill this gap, in the current work two automatic approaches are proposed in order to optimize the variance estimation. Through a numerical example, we show that, when the estimation framework is used in conjunction with these two proposed variance-estimation approaches, it can achieve reasonable performance in terms of matching both the measurements of the physical sensors and the true underlying flow rates. (paper)

[en] Objective: To investigate functional connectivity changes in Parkinson disease in the resting brain using functional magnetic resonance imaging. Methods: Nine patients with Parkinson disease and eight age-matched healthy volunteers were entered into the study. The bilateral globus pallidus were chosen as seed points, the functional MR data acquired in the resting state were processed to investigate functional connectivity in PD patients and the results were compared with those of the controls. Results: In age-matched healthy controls, there are regions which had functional connectivity with bilateral globus pallidus, including bilateral temporal poles, bilateral hippocampus, bilateral thalami, posterior cingulate cortex, right middle occipital gyms and right superior parietal gyms. In PD patients, brain regions including bilateral cerebellum, left hippocampus, bilateral superior temporal gyri, left inferior frontal gyrus, left middle frontal gyrus, left precentral gyrus, left inferior parietal gyrus and left superior parietal gyrus, had functional connectivity with bilateral globus pallidus. Compared to healthy controls, increased functional connectivity in bilateral cerebellum, bilateral temporal lobes, left frontal lobe and left parietal lobe, and decreased functional connectivity in bilateral thalami were observed in PD patients. Conclusion: Abnormal changes of brain functional connectivity exists in Parkinson's disease in the resting state. (authors)

[en] Microstructure evolution during homogenization of a low-alloying τ-type Mg-Zn-Al magnesium alloy with a nominal composition of Mg-7% Zn-3% Al was investigated in this paper, using optical microscopy, scanning electron microscopy, X-ray diffraction, differential scanning calorimetry analysis and quantitative image analysis. A anneal treatment following rapid cooling to ambient temperature from homogenization isothermal temperature was adopted to assess the homogenization degree in respect to microchemical distribution. The results show that shorter holding time results in so-called in situ precipitation phenomena, which is attributed to the insufficient diffusion of the element Zn and Al from solute-rich grain boundary region to inner side of grain during homogenization. A homogenization treatment at 325 deg. C for at least 50 h is just enough allowing complete homogenization for such alloy, in point of both morphology and microchemistry of the microstructure, which is deemed to be a key precondition for the optimum combined properties through proper thermal-mechanical treatment

[en] This paper proposes a new approach to problems of data assimilation, also known as history matching, of oilfield production data by adjustment of the location and sharpness of patterns of geological facies. Traditionally, this problem has been addressed using gradient based approaches with a level set parameterization of the geology. Gradient-based methods are robust, but computationally demanding with real-world reservoir problems and insufficient for reservoir management uncertainty assessment. Recently, the ensemble filter approach has been used to tackle this problem because of its high efficiency from the standpoint of implementation, computational cost, and performance. Incorporation of level set parameterization in this approach could further deal with the lack of differentiability with respect to facies type, but its practical implementation is based on some assumptions that are not easily satisfied in real problems. In this work, we propose to describe the geometry of the permeability field using B-spline curves. This transforms history matching of the discrete facies type to the estimation of continuous B-spline control points. As filtering scheme, we use the ensemble square-root filter (EnSRF). The efficacy of the EnSRF with the B-spline parameterization is investigated through three numerical experiments, in which the reservoir contains a curved channel, a disconnected channel or a 2-dimensional closed feature. It is found that the application of the proposed method to the problem of adjusting facies edges to match production data is relatively straightforward and provides statistical estimates of the distribution of geological facies and of the state of the reservoir.

[en] BTO/CMZFO composite ceramics with different molar ratios (the molar of BTO to that of CMZFO) (3:1, 2:1, 1:1, 1:2, 1:3) were prepared by conventional solid state reaction method. Effects of molar ratio on the dielectric, magnetic properties and coupling effect were investigated. The results indicate that the ceramics show bi-phase composite structure, without any obvious impurities can be found. The grain size can be categorized into two types, one is BTO with the grain size of 2–3 μm while the other one is CMZFO with the size less than 0.5 μm. The dielectric constant of all the composites is less than 500 in the frequency range from 20 to 2 MHz, and it decreases with decreasing the molar ratio while the dielectric loss shows the opposite behavior. The frequency stability of dielectric constant decreases with the addition of CMZFO due to the increased relaxation polarization. The dielectric constant and loss present non-monotonic dependence on the molar ratio, one or more relaxation peaks can be found. With the reduction of molar ratio, the height of the relaxation peak decreases and the position of the relaxation peak shifts to lower temperature. The remnant polarization (P_r) range is from 2 to 7.5 μC/cm², it decreases first and then increases with the molar ratio, this non-monotonic transition can be attributed to the combined action of ferroelectric phase and leakage current. The magnetization decreases and then increases with the diminution of molar ratio, the largest remnant magnetization (M_r) of the composites is 31.52 emu/g when the ratio is 1:3. The largest effective magnetization of CMZFO component in the composite is 84.855 emu/g for the specimen with the molar ratio 2:1, which is due to the strongest interface interaction between the two phases compared with other samples. The coupling coefficient increases rapidly and then decreases slowly with the applied magnetic field, and the maximum coupling coefficient is near 1.2 mV/cmOe, which is obtained at about 2 kOe in the sample with the molar ratio 1:3.

[en] Co_0.5Ni_0.5Fe₂O₄(CNFO) were prepared by chemical coprecipitation method and the particles were tuned by varying annealing temperature (400, 500, 600, 700 and 800 °C), and on this basis, CNFO/Ba_0.85Sr_0.15TiO₃ (BST) composites were prepared by sol–gel method. Effects of CNFO particle size on the microstructure, dielectric and multiferroic properties were systematically investigated and discussed. The results confirm pure CNFO and BST phases, without any obvious impurity phases. The particle size of CNFO is in the range of 20–50 nm, and all the composites show relatively uniform grain size except some pores presented on the surface. The dielectric constant and loss decrease with the particle size as a whole, while the permittivity shows strong dependence of the measuring frequency due to the relaxation polarization mechanism, of which the relaxation peak decreases and shifts to high temperature range with the frequency. The polarization increases with the testing voltage but decreases with the test frequency increasing, the remnant polarization decreases with the increase of particles size, the highest value is 2.2 μC/cm², obtained at 100 Hz for the sample with the smallest particle size. The maximal remnant magnetization is 11.2 emu/g, which is also obtained when the particle size is the smallest due to its strongest interface interaction. The ME coefficient decreases with increasing the particles size and the maximum ME coefficient is about 13.2 mV/(cm Oe). These results provide valuable information for improving the magnetoelectric properties of composites by tuning the particles size.