二维磁性材料与自旋系统研究进展

自旋系统是一类基于电子自旋工作的器件,具有高速、低功耗等优点,其中磁存储器被认为是下一代存储器的领跑者之一。二维材料有着天然的界面性能优势,接近微缩极限的尺寸特点,以及二维结构带来的物理特性,在自旋系统中有望得到广泛运用。本文概述了二维材料在自旋领域的最新研究进展,介绍了一些常见的二维磁性材料,讨论了基于二维材料的二维自旋器件,以及回顾了基于二维材料的磁性调控,最后总结了这一领域仍然面临的挑战,并对未来发展进行了展望。     

中国大中型气田天然气的运聚特征

中国重点盆地大中型气田天然气的运聚具有多种途径和方式,归纳起来具有如下特点:区域构造运动是造成天然气运移的决定性控制因素;流体势决定天然气运移的方向和聚集的场所。在断陷盆地中,天然气以垂向和阶梯状运移为主;在克拉通、前陆斜坡和大型坳陷盆地中,天然气以侧向运移为主,垂向运移也起重要作用。断裂和不整合面是天然气运移的主要通道;异常压力是高压盆地天然气运移的主要动力,地热对热盆天然气的运移具有一定的影响;盆地的上倾方向和古隆起是天然气运移的指向区。     

Completion and stimulation trends in North American unconventional plays and resulting impact on well productivity

过去十年,非常规油气勘探开发在全球范围内大幅扩张。水平钻井和多级水力压裂技术也在不断地发展和创新,使得超长水平井成为可能。同时,因为压裂强度不断增加,作业者可以最大限度地提高储层接触面积和对储层的改造体积 （SRV）。然而,完井优化方面的挑战仍然存在,作业者持续不断地尝试和试验各种完井与增产参数组合,以确保非常规油气藏开发的经济可行性。优选最佳的完井与增产参数组合是一项非常关键的任务,应结合油气田的具体储层特征进行优化。本文总结了2014—2020年间北美9个主要非常规油气藏的压裂增产趋势,包括Marcellus, Haynesville, Barnett, Utica, Bone Spring, Bakken, Wolfcamp Midland, Eagle Ford, Scoop/Stack。分析了各油气田几个关键的完井和增产参数的整体趋势,同时还评估了单个参数（如水平段压裂长度、支撑剂强度、段间距等）对井产能的影响。然后对比分析相应的初始井产量（90 天平均初始产量）,评估各个参数对产能的影响,从而确定每个完井参数的最佳范围,以实现产能最优化。     

高应力动压巷道围岩冲击破坏机理与防治技术研究

以宝积山煤矿705工作面沿空侧回风平巷为工程背景,采用现场调研、理论分析、电镜扫描、数值模拟和现场工业性试验等相结合的研究方法,对水射流钻割冲孔防治冲击地压技术进行了研究。结果表明:水射流以基本段射流对孔壁的钻割为主,冲孔后孔壁周围塑性区内煤体裂隙十分发育;冲孔期间钻头沿钻孔轴向连续式运动,所形成的柱体状冲孔空间能够实现对煤体的卸让压增透效果,煤体内会重新形成应力峰值并呈“内低外高”的“双峰值”应力曲线;冲孔直径为420 mm、两相邻钻孔之间中心距为5 m、冲孔段长度取10 m时卸让压增透效果最佳。现场工业性试验期间,电磁辐射和瓦斯流量衰减监测数据验证了该冲孔防冲技术的有效可行性。     

宜昌磷矿岩体移动分析的Fuzzy数学方法

针对宜昌磷矿地下开采岩体移动变形问题 ,利用Fuzzy数学理论建立了相应的数学模型。该数学模型和分析方法不仅适用于分析高陡山区复杂地形条件下 ,同时也适用于分析水平地表下开采地表移动变形问题。所建立的数学模型可充分考虑地表地形 ,尤其对分析地表自然坡度α≥ 3 0°的情形仍可充分顾及地表地貌影响 ,反映出地表高差变化影响。同时 ,还就山区开采自然坡稳定问题给出了理论模型     

Effects of land use and changes in cover on the transformation and transportation of iron:A case study of the Sanjiang Plain,Northeast China

Wetland reclamation has been ongoing in the Sanjiang Plain since the mid-1950s,which has resulted in major changes in wetlands and the agriculture ecosystem in the region that have influenced the iron output to the Sea of Okhotsk and limited the primary productivity in the North Pacific Ocean.This study was conducted to investigate the chemical forms of iron in different aquatic environments(agricultural water including groundwater,paddy water,and canal water;wetland water including marsh water,marsh stream...     

云南省磷矿资源开发面临的问题及建议

云南省乡镇和个体小矿泛滥 ,资源浪费大 ,环境破坏严重 ,磷矿石市场混乱。建议走可持续发展之路 ,建立健全综合管理体系 ,加大探矿找矿力度 ,加强中低品位磷矿石的选矿研究 ,全面推进矿山化工。     

Classroom logistics: Integrating digital and non-digital resources

This response to Dillenbourg's postulations on Orchestration analyses the relationship between classroom logistics and learning. It is necessary to detail the precise actions that the teacher must perform in order to apply the proposed strategies for the integration of digital and non-digital resources. It is not about teacher training; it is about giving teachers the tools to structure their classes and empower them beyond the training process. Every aspect of the class should be specified, leaving what finally will be performed to the teacher. We conclude that an adequate orchestration helps to guide the teacher through the work to be performed in the classroom, allowing a shift from an instructor-centered arrangement, in which the teacher radiates knowledge before a passive class of students, to one where the students actively participate, with the teacher acting as a mediator.     

Designing a powerful learning environment to promote durable conceptual change

The purpose of this study was to investigate the long-term effectiveness of a three-dimensional (3D) computer modeling supported predict–observe–explain (POE) strategy on pre-service science teachers' understanding of lunar concepts. Thirty-three preservice teachers participated in the study. A questionnaire was used to assess participants' understanding of the phases of the Moon and eclipses before, after, and 22 months after the instruction. Semi-structured interviews were conducted with six participants before and after the instruction. The results demonstrated that few participants had a scientific understanding about the targeted lunar concepts before the instruction. However, the majority of the participants had a scientific understanding after the instruction indicating that the instructional intervention was quite effective in facilitating conceptual change. The results also demonstrated that twenty-two months after the instruction most participants maintained their scientific conceptual understanding suggesting that the powerful learning environment designed for this study was effective in promoting a durable conceptual change.     

甘肃工业项目现状、问题与对策分析

本文在对甘肃省工业项目的总体情况进行分析的基础上,对全省工业发展过程中,项目工作存在的主要问题进行了探讨,从项目应把握的基本原则、关系、重点工作、服务意识、推进机制等方面提出了一些加快推动项目的思路和措施。