教育网站个性化推荐系统中的一种用户兴趣模型的建立

用户兴趣模型用于描述用户的个人信息、专业背景、偏好倾向和历史行为等,通过这些信息,系统可以发现和预测用户的信息需求,从而对用户进行个性化的信息推荐服务.用户兴趣模型是影响推荐系统服务效率的重要因素,因此针对用户兴趣进行建模是个性化推荐系统实现中要重点考虑的问题之一.本文从教育网站用户对象特点出发,提出了将用户兴趣分为固定兴趣与临时兴趣相结合的动态模型.     

Performance evaluation of lateral flow immuno assay test kits for quantification of deoxynivalenol in wheat

Lateral flow immuno assay test kits for determining the presence of deoxynivalenol (DON) in grain provide relatively simple, cheap and quick detection means, but are only useful if they provide reliable and accurate results. This study aimed to evaluate the performance of four different lateral flow immune assay test kits, being Reveal Q+ DON (Neogen), Donsensor (Unisensor), RidaQuick DON (R-Biopharm AG), and RosaFast DON (Charm Sciences Inc.). The performance was evaluated based on accuracy, repeatability, and toxin recovery of the test kits using three types of wheat sample material. These included samples spiked at three different DON concentrations, reference material with a DON concentration of 900 μg/kg, and naturally contaminated samples with a wide range of DON concentrations.Results revealed that, in general, Reveal Q+ and Donsensor were the most accurate methods, whereas the performances of RidaQuick and RosaFast were much lower. Mean toxin recovery and repeatability of Reveal Q+ and Donsensor complied with EC requirements for analytical methods used for official control of DON in foodstuffs. Reveal Q+ and Donsensor also showed high accuracy. RidaQuick and RosaFast showed lower performance, in particular recovery of RidaQuick was lowest. However, laboratory procedures for the latter two test kits were easier to follow. In particular, RidaQuick has the easiest testing procedure and can be applied on-site without technical skills. Future research could focus on a more in-depth evaluation of the performance of Reveal Q+ and Donsensor, also including evaluation of between laboratory reproducibility.     

工程岩体设计分类及模糊综合评价方法

为了更准确、客观地反映岩体分类,直接地说明岩体对于目标工程的分类等级,本文在原有工程岩体分类的基础上,加入了工程建筑活动因素及相应的评价标准。并使用了模糊综合评价方法,建立了工程岩体设计分类方法,通过实际应用检验,得到了较好的效果,分类结果符合岩体分类要求,反映了岩体的真实状态。     

构建三层技术架构的数字化教学资源体系

随着高校数字化教学资源建设的不断发展与完善,数字化资源呈现多元性和分散性,数据类型离散性也越来越大.由于高校资源建设存在一定程度上的重叠,导致出现重复投资问题.为优化资源建设,以适应高校图书馆21世纪发展的需要,渠道丰富的教学资源建设必须重组、优化和整合.为此,根据教学资源的数据特点和存储特性,提出了教学资源海量存储的设计方案和三层技术架构的整合模型,并介绍了深圳职业技术学院典型工程案例.     

The Visceral City and the Theatre of Fear

Over the last decade in India, intensive urbanisation, with the aid of the mass media, has unleashed a new culture of fear. Widespread access to TV, text messaging and the Internet have heightened and played upon individuals' anxieties. Ravi Sundaram describes how in Delhi, in particular, the media provided the catalyst for ‘mass hysteria’ and ‘psychosis’ during the summer of 2002. Copyright © 2007 John Wiley & Sons, Ltd.     

混凝土温度跟踪养护仪的研制及应用

对混凝土试样实施温度跟踪养护,可以模拟混凝土在某种保温环境中,在自身水化热的影响下,其水化产物、体积稳定性和力学性能的变化规律.基于虚拟仪器的思想,研制了混凝土温度跟踪养护仪.试验结果表明:该温度跟踪养护仪可依据设定的温度变化历程很好地完成对混凝土试样的养护,同时,相对于恒温(T=20℃)条件下养护的混凝土试样,对混凝土试样实施温度跟踪养护可提高其抗压、抗折强度和弹性模量.     

聚丙烯腈纤维对引气混凝土抗冻性的影响

采用快速冻融法,以质量变化和相对动弹性模量作为混凝土抗冻性能的评定指标,研究了聚丙烯腈纤维在三个体积掺量0.07%、0.1%、0.13%时对C30、C45和C60引气混凝土抗冻性的影响,其中引气混凝土含气量为4%.结果表明掺加聚丙烯腈纤维的引气混凝土的冻融破坏形态为表面剥落破坏,纤维混凝土在冻融作用下的内部损伤减轻.掺加聚丙烯腈纤维的C30、C45引气混凝土的抗冻性得到了很大的改善,纤维体积掺量为0.1%时,抗冻性最好;但聚丙烯腈纤维对高强度等级的C60引气混凝土的抗冻性提高幅度不明显.     

子结构质量对MSCS的控制效果分析

建立了随机脉动风载下巨-子型有控结构(MSCS)的动力方程;基于复模态理论,推导了MSCS在随机风载激励下的协方差函数、位移及加速度响应功率谱和均方响应表达式;讨论了子结构质量对MSCS控制效果的影响。     

氧化镁膨胀剂及其在大体积混凝土中的应用

现行的混凝土外加剂规范中,未列入MgO膨胀剂。试验研究和工程实践证明,在大体积混凝土中掺入适量的MgO膨胀剂,混凝土具有良好的力学性能和延迟微膨胀特性。充分利用这种特性,可以补偿混凝土的收缩变形,提高混凝土自身的抗裂能力,从而达到简化大体积混凝土温控措施、加快施工进度和节省工程投资的目的。为促进MgO膨胀剂的推广应用,建议将MgO膨胀剂列入我国混凝土外加剂类规范中。     

大体积混凝土基础冬期施工的温度裂缝控制

针对大体积混凝土早期温度裂缝产生的机理,结合大体积混凝土冬期施工的特点提出了混凝土早期裂缝的控制措施,从而使混凝土基础底板的早期温度裂缝得以有效控制。