复杂理论视阈下动态课堂场域的控制与自主研究

文章从复杂理论的角度分析了课堂教学过程是一个复杂的动态适应过程,是教师和学生之间的"复杂对话".从而指出课堂教学的动态性和复杂性,要求教师在课堂场域把握教学过程的复杂性、实现目标与教学模式的匹配、拥有必要的理解力和课堂管理技能,帮助学生实现自主学习,并最终实现课堂教学过程的最优化.     

基于MRIO与SNA的中国水资源空间转移网络分析

基于2002年、2007年和2012年的多区域投入产出表的相关数据,利用多区域投入产出(MRIO)模型和社会网络分析法(SNA)分析了中国水资源流动网络的空间关联性和结构特征。结果表明:网络中的链接数量没有随水足迹贸易值的增加而增加,链接路径上的流量不断增加,网络的韧性不够,空间关联渠道有待拓展,存在一定的等级差异,稳定性需要加强;网络中一些省份链接的增加,会削弱其他省份的链接数目,这种可塑性特征有利于在全国范围内合理配置水资源;将网络划分为4个板块,板块间的溢出关系主要是以板块内部为主,且少数板块之间没有任何的溢出关系。     

一种改进的嵌入式电子地图空间索引

空间索引在嵌入式设备中有广泛的应用,按照不同的空间映射方式,可以分为不同的索引方法,如二叉树索引、网格索引、四叉树索引和R树索引及其变种,指出了各种空间索引的利弊和适用环境.目前嵌入式系统中硬件资源不足,人们对其功能的需求却在不断的增加,因此如何快速的检索到需要的空间数据以满足相应的功能成为了一个亟需的问题.根据各个索引方法优势以及其相关的使用环境,提出了一种四叉树和R*-树相结合的空间索引—QR*-树索引,此空间索引虽然在存储空间上比R*树略有增加,但是在插入、删除、查找等操作中的性能远远优于R*-树,非常适合作为嵌入式系统的数据库空间索引,最后在S3C2440平台上验证了其有效性.     

动态网络中行业因素与股市波动性研究

股票市场的波动性一直是金融领域的一个研究重点,行业因素对股市波动性的影响也是投资者关注的一个焦点.从复杂网络视角出发,以行业内股票相关性强弱(RIL)为指标实证研究了行业因素与股票波动性之间的联系.研究发现不同行业的RIL指标有不同的参考标准,于是对原有的RIL指标进行了改进得到新指标RIL*.在以沪深300样本股为例的实证研究中发现采矿业、金融业和房地产业内的股票受行业因素影响最强.研究还发现股票网络结构变化和股市波动性之间存在联系,当行业因素影响急剧降低时,行业内的股票走势会猛烈上升或下降.     

众筹筹资模式发展浅析

依据众筹相关法律完善程度可把众筹的发展划分为雏形、快速发展和逐步成熟三个阶段。众筹包括捐赠、回报、股权和债券等常见模式。发展众筹一方面可以降低创业者的融资门槛,另一方面可激发草根的创新热情。然而,众筹项目知识产权保护欠缺、我国法律对股权众筹的限制、人们对众筹认识不足等一系列问题严重阻碍了众筹的发展。为了解决这些问题,众筹平台应积极与政府相关部门交流沟通,完善法律法规,利用社交媒体扩大众筹的影响力,并加强风险管控。     

Deformation transition of intact coal induced by gas injection

Gas migration in coal bed is a multiple-physical process, of which not only includes gas desorption/diffusion through coal matrix and gas Darcy flow through the cleat system, but also results in deform...     

大学英语课堂教学中合作学习有效性探讨

合作学习已经越来越多的被大学教师引入到英语教学中。文章探讨了合作学习中遇到的问题,分析合作学习受阻的原因,提出解决问题的对策。     

磁场中双量子位Heisenberg模型的纠缠与量子相变

以双量子位Heisenberg模型为例,讨论了磁场方向对纠缠的影响。结果表明：一定温度下,保持磁场的大小不变,仅改变其方向,不仅能获得最大纠缠,还产生了量子相变。     

Degradability and biocompatibility of bioglass/poly(amino acid) composites with different surface bioactivity as bone repair materials

Bioglass (BG) possesses excellent bioactivity and has been widely used in the manufacture of biomaterials. In this study, a composite with different surface bioactivity was fabricated via in situ melting polymerization by incorporating BG and poly(amino acid) (PAA) at a suitable ratio. The structure of the composite was characterized by Fourier transform infrared spectroscopy and XRD. The compressive strength of the BG/PAA composites was 139 MPa (BG:PAA = 30:70). The BG/PAA composites were degradable, and higher BG in composite showed higher weight loss after 4 weeks of incubation in simulated body fluid. In addition, the BG/PAA composite maintained adequate residual compressive strength during the degradation period. The SEM results showed the differences in surface bioactivities of the composites directly, and 30BG/PAA composite showed thicker apatite layer and higher Ca/p than 15BG/PAA. in vitro MG-63 cell culture experiments showed that the composite was noncytotoxic and thus allows cells to adhere, proliferate, and differentiate. This indicates that the composite has good biocompatibility. The implantations in the bone defects of rabbits for 4 and 12 weeks were studied. The composites had good biocompatibility and were capable of guiding new bone formation without causing any inflammation. The composite may be successfully used in the development of bone implants.     

Weathering modification of acrylic emulsion by introducing UV absorbing groups

A new kind of UV-absorbing silicon-fluorinated acrylic emulsion was prepared by emulsion polymerization with 4-allyloxy-2-hydroxybenzophenone, 3-methacryloxypropyltrimethoxysilane (MPS) and hexafluorobutyl methacrylate (HFMA) as functional monomers. The emulsion and its coating were characterized by transmission electron microscope, Fourier transform infrared spectrum (FTIR), X-ray photoelectron spectroscopy, ultraviolet absorption spectrum,thermo-gravimetric analysis, water contact angle (CA), and artificial accelerated aging test. The results indicated that the emulsion with core-shell structure was synthesized and showed prominent absorption peaks at 320 and 350 nm. The water CA of the coating was increased from 70.2° to 86.7° because of the incorporated HFMAs and MPSs. Both of the initial and final decomposition temperatures of the coating were increased by more than 20°C compared with those of the unmodified coating. After 10 days of accelerated aging, the color difference (ΔE) and rate of loss of gloss (ΔG) were only 2.78% and 5.22%, while those of the unmodified coating were as high as 22.94% and 78.57%, respectively. Because of the UV absorbers were incorporated by chemical reaction, the new coating had a more durable and effective anti-ultraviolet performance compared with the coatings the UV absorbers were introduced by physical blending.