Magnetostructural Transformation and Magnetoresponsive Properties of MnNiGe1-xSnx Alloys

The martensitic and magnetic phase transformations in MnNiGe1-xSnx (0 \leq x \leq 0.200) alloys were investigated using X-ray diffraction (XRD), differential thermal analysis (DTA) and magnetization measurements. Results indicate that the increasing Sn substitution in MnNiGe1-xSnx results in (i) decrease of martensitic transformation temperature from 460 to 100 K and (ii) conversion of AFM spiral to antiparallel AFM strcuture in martensite. Based on these, the remarkable magnetic-field-induced PM/spiral-AFM and FM/AFM magnetostructural transformations and, large positive and negative magnetocaloric effects are obtained. The magnetoresponsive effects of MnNiGe1-xSnx alloys are enhanced by Sn substitution. A structural and magnetic phase diagram of MnNiGe1-xSnx alloys has been proposed.Comment: 3 pages and 4 figure

A Model-Driven Method for Quality Reviews Detection: An Ensemble Model of Feature Selection

With the rapid growth of e-commerce and user-generated content online, the increasing product online reviews have significant influence on both buyers and sellers. However, among the thousands of online reviews, only the reviews of high-quality matters to the market, thus quality reviews detection rises in response to the requirement of retrieving authentic feedbacks from consumers. In this paper, a state-of-the-art ensemble model, gradient boosting decision trees (GBDT), is applied to select useful features for quality evaluation of online reviews. Firstly, four types of features are extracted based on information adoption theory. Then, the GBDT model is adopted to select useful features for quality reviews detection. At last, comparative experiments are conducted through online reviews of searching goods, based on two baseline models such as Decision Tree and Logistic Regression, and the results show that GBDT model achieves a better performance in detecting reviews of high-quality. This research indicates that product attributes, reviewer characteristics and objectiveness of reviews are key ingredients in high quality reviews

Control of laser-plasma instabilities by non-collinear polychromatic light

Normal broadband lasers with collinear polychromatic components have immense potential for mitigating laser plasma instabilities (LPIs). However, the projection complexity of collinear polychromatic light (CPL) is a significant challenge owing to the demand for a large bandwidth and beamlet number. Here, we propose a theoretical LPI model and optical design for non-collinear polychromatic light (NCPL), which has a small angle $\sim4^\circ$ and large frequency difference $\sim$1\% between the double-color beamlets. LPI models of the NCPL demonstrate a decoupling threshold for the shared daughter waves under a multibeam configuration. Compared with the CPL, the wavevector couplings are further reduced by the introduced angle. Therefore, both the growth rate and saturation level of LPIs are greatly reduced by using the NCPL. The two- and three-dimensional simulation results indicate that the NCPL reduces the absolute and convective decoupling thresholds of the CPL and is sufficient to effectively mitigate the reflectivity, hot-electron generation, and intensity of cross-beam energy transfer. An optical design for the efficient generation of ultraviolet NCPL has been presented based on the unsaturated optical parametric amplification and non-collinear sum-frequency generation

Microscopic remaining oil distribution and quantitative analysis of polymer flooding based on CT scanning

  To investigate the distribution characteristics of remaining oil after polymer flooding, the core samples of different stages of water flooding and polymer flooding were scanned and imaged based on CT scanning technology. The oil, water and rock were divided into three phases by image analysis method, and the corresponding digital cores were constructed. Through the qualitative and quantitative analysis of the two-dimensional image and three-dimensional structure at the same position, the quantitative characterization of the micro-residual oil distribution in different displacement stages is finally realized. The results show that, the polymer flooding can significantly improve the sweep efficiency, which can increase the oil recovery by 11.45% compared with water flooding. The remaining oil in the pore is mainly network and multiple, and mainly network distribution at the stage of water flooding. After adding polymer, the proportion of multiple remaining oil increases significantly and becomes the main occurrence state of remaining oil. Affected by Jamin effect, multiple residual oil in the pore is difficult to be recovered because it cannot pass through the throat. The radius of this part of remaining oil is usually 1.34-1.5 times that of the throat radius.Cited as: Wang, X., Yin, H., Zhao, X., Li, B., Yang, Y. Microscopic remaining oil distribution and quantitative analysis of polymer flooding based on CT scanning. Advances in Geo-Energy Research, 2019, 3(4): 448-456, doi:10.26804/ager.2019.04.1