Supporting primary students' learning of fraction conceptual knowledge through digital games

With the advent of mobile technologies, well-designed fraction apps can be used to help children gain fraction knowledge, a challenging topic for both teachers and students. The present pilot study adopted a quasi-experimental design to investigate whether children can learn fraction concepts equally well if half of the lesson time (20 min) is replaced with game-based learning. Keeping the total lesson time (40 min) identical, the control group (N = 33) received traditional instruction, and the experimental group (N = 32) was presented with a blended learning approach spending half of the class time (20 min) playing tablet-based fraction games, where each of the learners had their own tablet. The results suggested that in the posttest, the experimental group achieved similar learning gains to the control group and appear to have achieved better performance in the transfer test than the control group. This paper also discusses the efficiency of game-based learning, the mechanism of how fraction games might enhance learning, and the potential of integrating game-based learning in educational settings.     

Characteristic of polysaccharides from Flammulina velutipes in vitro digestion under salivary,simulated gastric and small intestinal conditions and fermentation by human gut microbiota

In this study, in vitro digestion and fermentation of Flammulina velutipes -derived polysaccharides (FVP) were investigated. It was found that FVP mainly consisted of 48.45% glucose, 15.40% mannose, 14.60% xylose, 11.80% fucose and 9.90% galactose. The -human saliva, simulated gastric and small intestinal juices conditions did not break down the FVP. Based on in vitro fermentation tests, FVP modulated the composition of gut microbiota by elevating the amounts of Bifidobacteriaceae and Bacteroidaceae and reducing the numbers of genera Lachnospiraceae and Enterococcaceae. Meanwhile, FVP affected the synthesis of short-chain fatty acids derived from gut microbiota.     

Adaptive compensation of persistent actuator failures of nonlinear systems

In this article, adaptive compensation designs are developed for nonlinear systems with uncertainties from the system functions and persistent actuator failures of characterizations that (i) some unknown system inputs are stuck at some unknown fixed or varying values at unknown time instants and (ii) the failure pattern always switches from one to another and the switching does not stop. Such a controlled plant is described by an uncertain time-varying nonlinear system, and some robust adaptive feedback linearization based failure compensation results are studied for closed-loop system stabilization and bounded output tracking for some specific conditions. To improve the tracking performance in the presence of persistent actuator failures, a new adaptive control scheme is developed, using the failure indicator function which contains the failure pattern and failure time in the formulation. Detailed stability and tracking performance are shown. Simulation results are shown to verify the effectiveness of the proposed adaptive actuator failure compensation method.     

双膦胺镍-甲基铝氧烷体系催化苯乙烯聚合

研究了具有新型结构的双膦胺镍配合物N,N-双(二苯膦基)-对甲氧基苯胺二氯化镍-甲基铝氧烷(PNP-N i-MAO)催化体系对苯乙烯聚合的催化性能,考察了聚合温度、n(A l)∶n(PNP-N i)、PNP-N i的浓度和苯乙烯的浓度对催化活性、苯乙烯转化率、聚苯乙烯相对分子质量及其分布的影响,并用核磁共振和凝胶色谱对聚苯乙烯的结构进行了表征。实验结果表明,在聚合温度25℃、聚合时间1h、n(A l)∶n(PNP-N i)=300、c(苯乙烯)=2.3m ol/L、c(PNP-N i)=0.4mm ol/L、甲苯为溶剂的适宜条件下,苯乙烯的转化率可达95%以上,催化活性达到5×105g/(m ol.h)左右。核磁共振和凝胶色谱表征结果显示,所得聚苯乙烯为无规结构,重均相对分子质量约为1×104,相对分子质量分布Mw/Mn约为2。     

真空铸造高强度C/Mg复合材料

本文介绍用真空铸造法制造抗拉强度超过1000MPa的高强度C/Mg复合材料。将T300纤维经C-Si-O梯度涂层处理后单向排布于型腔内,在真空下注入ZM-5合金液,凝固后即得C/Mg复合材料零件或试样。试样的抗拉强度在纤维体积分数为0.35时达1050MPa。本文讨论C-Si-O梯度涂层对获得高强度复合材料的作用。     

On loop transformations for generalized cycle shrinking

This paper describes several loop transformation techniques for extracting parallelism from nested loop structures. Nested loops can then be scheduled to run in parallel so that execution time is minimized. One technique is called selective cycle shrinking, and the other is called true dependence cycle shrinking. It is shown how selective shrinking is related to linear scheduling of nested loops and how true dependence shrinking is related to conflict-free mappings of higher dimensional algorithms into lower dimensional processor arrays. Methods are proposed in this paper to find the selective and true dependence shrinkings with minimum total execution time by applying the techniques of finding optimal linear schedules and optimal and conflict-free mappings proposed by W. Shang and A.B. Fortes     

砂砾岩储集层含油性解释方法

LJ地区砂砾岩地层具有岩石结构复杂，储集层非均质性强，稠油和稀油并存的特点，利用测井资料解释含油性难度很大，以地层测试资料为依据，综合利用多种测井信息，提取反映含油性变化的测井特征参数；应用测井参数交会法和测井相分析法建立有效，快速识别稠油，油层和水层的标准，测井相分析法消除了用测井单参数和两参数交会解释含油性存在的多解性，提高子解释结果的成功率，用编制的解释软件处理了LJ地区58口井的资料，解释结果与试油资料对比吻合程度较高，为砂岩储层含油性解释提供了一种有效，快速的方法，为该区先导性试验提供了可靠的依据。