Semi–cyclic Holey Group Divisible Designs and Applications to Sampling Designs and Optical Orthogonal Codes

We consider the existence problem for a semi‐cyclic holey group divisible design of type with block size 3, which is denoted by a 3‐SCHGDD of type . When t is odd and or t is doubly even and , the existence problem is completely solved; when t is singly even, many infinite families are obtained. Applications of our results to two‐dimensional balanced sampling plans and optimal two‐dimensional optical orthogonal codes are also discussed.     

A Doubling Construction for 3‐Uniform Friendship Hypergraphs with the Universal Pairs Property

In this note, we present a simple doubling construction for 3‐uniform friendship hypergraphs which generalizes the cubeconstructed hypergraphs from another study (L. Jørgensen and A. Sillasen, J Combin Designs (2014)). As a by‐product, we build point‐transitive 3‐uniform friendship hypergraphs of sizes and for all .     

Large Deviations of the Finite Cluster Shape for Two-Dimensional Percolation in the Hausdorff and L1 Metric

We consider supercritical two-dimensional Bernoulli percolation. Conditionally on the event that the open cluster C containing the origin is finite, we prove that: the laws of C/N satisfy a large deviations principle with respect to the Hausdorff metric; let f(N) be a function from to such that f(N)/ln N+ and f(N)/N0 as N goes to the laws of {x ² : d(x, C)f(N)}/N satisfy a large deviations principle with respect to the L ¹ metric associated to the planer Lebesgue measure. We link the second large deviations principle with the Wulff construction.     

Effect of Doping on Rutile TiO2 Surface Stability and Crystal Shapes

Transition-metal-(TM-)doped TiO₂ has been considered as promising electrode material for the oxygen evolution reaction (OER). OER activity is expected to depend on the coordination of the surface atoms. In this study, we theoretically investigate the stability of low-index surfaces of TM-doped rutile, (110), (100), (101) and (001), with 50 % of the Ti atoms substituted by Sc, Y, V, Nb or Ta. For Sc and Y, we also consider models with O vacancies providing the most stable oxidation state of Sc and Y. Surface energies are calculated with DFT(+U). Based on the Gibbs-Wulff theorem, the shape of the single crystals is predicted. It is observed that p-doping leads to spontaneous oxygen loss and O vacancies cause surface reconstruction. The Wulff shapes of n-doped TiO₂ have smaller contributions of the (110) facet and, for Nb and Ta, larger contributions of other facets. Given the higher coordinative unsaturation of the TM atoms in the latter, a higher catalytic activity is expected.     

基于新工科内涵的环境化学课程建设*

为了提高环境类人才实践与创新能力,重构了符合新工科理念的环境化学“素养、能力、知识”一体化课程目标;基于科研反哺课程内容增补了新工科元素“环境计算化学——化学品构效关系;基于线上线下混合式构建了“三三三”教学模式,进行了多元化过程考核方式探索,教学设计强化了学生的能力培养与价值塑造。课程建设实践表明,学生的学习获得感与其课堂参与度呈现正相关,基于身边老师的科研反哺和前沿拓展,更能激发学生的应用挑战兴趣,促进提升实践能力和创新能力。环境化学课程实现了全方位新工科内涵式建设,以期为环境工程专业的新工科升级改造提供借鉴。     

基于结构化认识和解决物质转化问题的思维模型建构*——以“氢氧化钠变质的实验探究”为例

以探究氢氧化钠变质为依托点,融合酸、碱、盐相关知识,在复习知识的同时,将结构化认识和解决物质转化问题的思维方法贯穿于课堂实验探究始终,帮助学生从“概念理解-模型建构-学习活动-真实问题-模型评价”5个维度,体验模型认知的具体过程。利用实验探究的手段解决学生的认知冲突,修正和完善模型,实现结构化认识和解决物质转化问题的思维模型建构,提升化学学科核心素养。     

化学类通识教育公选课的“三知三性”改革与实践——以“微量元素与人体健康”为例*

以综合性大学开设的化学类通识教育公共选修课“微量元素与人体健康”为例,应用“三知三性”的教学理念对课程进行改革与实践,将化学知识、医药卫生知识、人文历史知识进行有机融合,同时实现课程思政性、科普性、趣味性的协调统一,为大学化学与健康系列通识教育公选课的课程建设提供有效的新方法与新思路。     

OBTL模式下化学实验室安全课程的建设与探索*

结合本校化学实验室安全教育现状和OBTL教学模式特点,对“化学实验室安全”进行课程建设和探索,将成果导向理念贯穿建设全过程,根据预期学习成果反向设计教学目标、教学内容、教学方法和教学评价。在整个教学活动中,形成教师引导、学生为主体的学习共同体,并通过多元、多策略的教学活动和教学评价确保学习成果的实现。课程的建设和探索将有望进一步提高实验室人员的安全素养,为化学实验室安全提供主动防御的知识和能力保障,同时为同类高校化学化工类专业安全教育提供一种参考。     

基于模型建构解决酸碱滴定曲线解题思维障碍*

学生在解决酸碱滴定曲线情境问题时常常存在各种思维障碍,基于模型建构及其应用,有助于解决学生酸碱滴定曲线解题思维障碍。剖析例题内在结构要素,聚焦电解质溶液滴定曲线命题关注的5个点,即起始点、等料点、等量点、中性点、恰好点。从“五点”出发,进行解题思维模型的建构,指引学生解题思维的发散与收敛等。精选试题情境为载体,将建构的模型思维应用于酸碱滴定曲线相关问题的解决,助力于真实情境中思维的启发、精准切入与生成等。实践过程中提升学生的模型认知核心素养,提升学生的化学学科思维品质。     

Explicit constructions for perfect hash families

Let k, v, t be integers such that k ≥ v ≥ t ≥ 2. A perfect hash family (N; k, v, t) can be defined as an N × k array with entries from a set of v symbols such that every N × t subarray contains at least one row having distinct symbols. Perfect hash families have been studied by over 20 years and they find a wide range of applications in computer sciences and in cryptography. In this paper we focus on explicit constructions for perfect hash families using combinatorial methods. We present many recursive constructions which result in a large number of improved parameters for perfect hash families. The paper also includes extensive tables for parameters with t = 3, 4, 5, 6 of newly constructed perfect hash families.