Effect of in-app components,medium, and screen size of electronic textbooks on reading performance,behavior, and perception

Although many app-based textbooks are available for students, reading have not been thoroughly outlined. This study aimed to understand how changes from paper to electronic textbooks have affected the academic reading task, investigate student users’ perceptions of in-app components and screen sizes, and identify issues affecting in-app components and task requirements. A mixed factorial design experiment was employed. Results showed that there were no significant changes in comprehension and time spent reading between print text and the iPad. Yet, student highlighting, notetaking, and reading behavior and perception significantly changed based on condition. In addition, students struggled to use in-app components and found them frustrating especially when accounting for sentence splitting. The findings presented can assist in understanding the changes in student reading behavior, which can be used to improve interface design of future e-textbooks.     

Owner’s Risk Allocation and Contractor’s Role Behavior in a Project: A Parallel-mediation Model

Risk allocation decisions are of critical importance in project management. The present study proposes an explanation for how risk allocation in a contract motivates a contractor to cooperate with a project owner. Theories of risk allocation and trust were used to motivate the research. Using a survey methodology, we collected data concerning 124 construction projects in China. We found that risk allocation influenced the contractor’s role behavior through the contractor’s feeling of being trusted but not the contractor’s trust in the owner. Feeling of being trusted partially mediated the effect of risk allocation on the contractor’s in-role (i.e., contractual) behavior and fully mediated the effect on extra-role behavior. The study introduces a social and psychological view of the impacts of risk allocation to the project and engineering management literature. We contribute to theory by arguing and demonstrating the mediating effect of trust on the relationship between risk allocation and contractor behavior. From a practical standpoint, we conclude that contractual risk allocation has a significant impact on building a trusting relationship between owners and contractors and that contractors who feel trusted perform both contractually mandated actions and actions external to the contract more diligently, resulting in the likelihood of improved outcomes for both parties.     

铌酸对酯化反应催化性能的研究

研究了新型固体酸催化剂铌酸对乙醇及异戊醇与乙酸酯化反应的催化性能、研究表明热处理温度对水洗法制备的铌酸催化剂的催化活性有显著影响,在350℃处理时活性达到极大值.与HZSM-5相比,铌酸催化剂不仅在乙醇和乙酸的气相酯化反应中表现出良好的催比性能,而且在异戊醇和乙醇的液相酯化反应中亦表现出较好的催化活性和稳定性.     

Automatically modeling, simulating and explaining physical systems

This paper presents an interactive framework for constructing models from high-level specifications of real physical systems, deriving low-level simulations from the constructed models and then generating explanations of the simulated behavior to help engineers interpret and control the real physical systems. To demonstrate our method, we show an example of modeling river networks, which are eco-environmental engineering systems, to provide a computer-based solution to problems of simulating and controlling concentrations of water quality constituents in river networks[1].     

一种用户行为分析的动态备份机制

目前大多数分布式存储系统采用静态备份机制保证系统的高可靠性,灵活性差,不适合系统规模及用户访问量不断变化的存储系统．因此提出一种基于用户行为分析的动态备份机制,通过分析用户行为获得相关信息来动态改变备份数量及确定备份位置,具有较强的灵活性,适合大规模的分布式存储系统;实现动态备份系统将其应用于已建立的科技信息数据中心．通过实验分析表明,该动态备份机制能提高系统的可靠性。     

消失模涂料对EPS裂解产物传输特性的影响

针对消失模铸造过程中EPS模样裂解产物，涂料性能对铸件质量的影响，介绍了一种消失模涂料对EPS裂解产物传输特性的测试仪器吸测试方法。讨论了消失模涂料厚度、涂层高温透气率、涂料组分对EPS裂解产物传输特性的影响。     

聚乙烯加工流变改性剂对LLDPE／HDPE流变性能的影响

本文介绍在ＬＬＤＰＥ（７０４７）／ＨＤＰＥ（６０９８）共混物（重量比为９０：１０）中加０．５％、１．０％、１．３％、１．５％、２％的聚乙烯加工流变改性剂，采ＸＬＹ－Ⅱ型毛细管流变仪测其流变性能。结果表明，加入ＱＬＹ树脂后，该本系的剪切速率增，表观粘度下降，活化降低，熔体乃属假塑性流体。     

The effect of hydrogen bonding on the phase behavior of poly(ethylene-co-acrylic acid)-ethylene-cosolvent mixtures at high pressures

Experimental cloud-point data to 260 °C and 2,500 bar are reported to demonstrate the impact of two cosolvents, acetone and methanol, on the phase behavior of polyethylene, poly(ethylene-co-2.4 mol% acrylic acid) (EAA_2.4), poly(ethylene-co-3.9 mol% acrylic acid) (EAA_3.9), poly(ethylene-co-6.9 mol% acrylic acid) (EAA_6.9), and poly(ethylene-co-9.2 mol% acrylic acid) (EAA_9.2) in ethylene. In pressure-temperature (P-T) space, the miscibility of EAA copolymers in ethylene decreases significantly with temperature and with increasing acrylic acid content of EAA due to self-association of the acrylic acid segments. Acetone and methanol, both dramatically enlarge the solubility of EAA copolymers due to the hydrogen bonding with acrylic acids in the EAA. At low concentrations, methanol is a better cosolvent than acetone. However, the impact of methanol diminishes rapidly with increasing methanol concentration once all the acrylic acids in the EAA are hydrogen bond with methanol molecules.     

聚苯硫醚／聚砜共混物的动态黏弹行为及相容性研究

研究了聚苯硫醚／聚砜熔融共混物的的加工流变行为以及共混物在不同温度下的动态黏弹响应；并对其相容性作出判断。结果表明，聚苯硫醚的加入显著改善了共混物的流动性，使其可在较低温度下成型；熔融态共混体系的相容性较差，固态条件下的相分离程度及损耗因子峰值大小依赖于组成变化。     

高浓色母粒的制备及流变行为研究

通过调控加工工艺及选择母粒配方，成功地制备出质量分数为70％的高浓白母粒。通过SEM观察发现，即使钛白粉质量分数高达70％．载体树脂仍可形成网状结构的连续相。测试母粒流变性能表明，高浓白母粒熔体仍为假塑性流体，流变行为稳定连续，且切力变稀的趋势较纯树脂更为明显；高浓白母粒与纯料共混时会出现等粘点，为色母粒的均匀着色提供了理论依据。制备出的高浓色母粒外观光洁，分散性能优良。