在线教学的实践与反思*——以有机化学课程为例

以有机化学课程在线教学开展情况为背景,通过与传统教学模式对比,分析了在线教学的优势与不足。在此基础上,将笔者所在课程组开展在线教学以来在教学内容重构、教学环节设计、考核方式改革等方面的探索与尝试进行了总结与分享。     

Cross‐linking and properties of rubber magnetic composites cured with different curing systems

Rubber magnetic composites were prepared by incorporation of strontium ferrite into rubber compounds based on acrylonitrile butadiene rubber and ethylene propylene diene monomer rubber. The sulfur, peroxide, and mixed sulfur/peroxide curing systems were introduced as cross‐linking agents for rubber matrices. The aim was to investigate the influence of curing system composition on curing process and cross‐link density of composite materials. Then, static and dynamic mechanical properties and thermal and magnetic characteristics were investigated in relation to the cross‐link density of rubber magnetic composites and structure of the formed cross‐links. The changes of dynamical and physicomechanical properties were in close correlation with the change of cross‐link density, whereas the tensile strength of magnetic composites showed increasing trend with increasing amount of peroxide in mixed curing systems. On the other hand, thermal conductivity and magnetic characteristics were found not to be dependent on the curing system composition.     

带有二元连接函数的半参数模型

提出了一种新的带有二元连接函数的广义半参数模型,即二元连接模型(简称为BLM).使用轮廓似然方法估计模型的参数和非参数部分,并给出了计算算法.证明了所得的未知参数的估计量为n~(1/2)-相合,渐近正态且具有渐近最小方差,给出了实际数据分析和模拟研究,最终采用局部功效方法来检验非参数部分的线性性.     

Preparation of Molecule‐Responsive Microsized Hydrogels via Photopolymerization for Smart Microchannel Microvalves

Microdevices designed for practical environmental pollution monitoring need to detect specific pollutants such as dioxins. Bisphenol A (BPA) has been widely used as a monomer for the synthesis of polycarbonate and epoxy resins. However, the recent discovery of its high potential ability to disrupt human endocrine systems has made the development of smart systems and microdevices for its detection and removal necessary. Molecule‐responsive microsized hydrogels with β‐cycrodextrin (β‐CD) as ligands are prepared by photopolymerization using a fluorescence microscope. The molecule‐responsive micro‐hydrogels show ultra‐quick shrinkage in response to target BPA. Furthermore, the flow rate of a microchannel is autonomously regulated by the molecule‐responsive shrinking of their hydrogels as smart microvalves.

     

An ensemble learning framework for potential miRNA-disease association prediction with positive-unlabeled data

To explore the pathogenic mechanisms of MicroRNA (miRNA) on diverse diseases, many researchers have concentrated on discovering the potential associations between miRNA and disease using machine learning methods. However, the prediction accuracy of supervised machine learning methods is limited by lacking of experimentally-validated uncorrelated miRNA-disease pairs. Without these negative samples, training a highly accurate model is much more difficult. Different from traditional miRNA-disease prediction models using randomly selected unknown samples as negative training samples, we propose an ensemble learning framework to solve this positive-unlabeled (PU) learning problem. The framework incorporates two steps, i.e., a novel semi-supervised Kmeans (SS-Kmeans) to extract reliable negative samples from unknown miRNA-disease pairs and subagging method to generate diverse training sample sets to make full use of those reliable negative samples for ensemble learning. Combined with effective random vector functional link (RVFL) network as prediction model, the proposed framework showed superior prediction accuracy comparing with other popular approaches. A case study on lung and gastric neoplasms further confirms the framework’s efficacy at identifying miRNA disease associations.     

Numeral eddy current sensor modelling based on genetic neural network

This paper presents a method used to the numeral eddy current sensor modelling based on the genetic neural network to settle its nonlinear problem. The principle and algorithms of genetic neural network are introduced. In this method, the nonlinear model parameters of the numeral eddy current sensor are optimized by genetic neural network （GNN） according to measurement data. So the method remains both the global searching ability of genetic algorithm and the good local searching ability of neural network. The nonlinear model has the advantages of strong robustness, on-line modelling and high precision. The maximum nonlinearity error can be reduced to 0.037% by using GNN. However, the maximum nonlinearity error is 0.075% using the least square method.     

Dynamic rating of European football teams

^** Formerly Knorr-Held. Email: held{at}stat.uni-muenchen.de In this paper we apply and extend recently proposed methodsfor the dynamic analysis of pairwise comparison data to Europeanfootball teams. Our statistical model is based on the cumulativelogistic link model with time-changing parameters for the strengthof each team. We jointly analyse the results from the five topEuropean leagues from 1996 to 2001 and all international matchesbetween teams from these leagues. We introduce weights for internationalmatches and also allow for a different size of the home teamadvantage in the different leagues. We suggest that the resultsfrom such an analysis may be taken as an alternative to theUEFA coefficient, which is currently used to determine the numberof teams from each league to take part in the European footballcontests.     

The Volume of Hyperbolic Alternating Link Complements

If a hyperbolic link has a prime alternating diagram D, thenwe show that the link complement's volume can be estimated directlyfrom D. We define a very elementary invariant of the diagramD, its twist number t(D), and show that the volume lies betweenv₃(t(D) – 2)/2 and v₃(10t(D) – 10), where v₃ isthe volume of a regular hyperbolic ideal 3-simplex. As a consequence,the set of all hyperbolic alternating and augmented alternatinglink complements is a closed subset of the space of all completefinite-volume hyperbolic 3-manifolds, in the geometric topology.2000 Mathematics Subject Classification 57M25, 57N10.     

On Spectrum Congestion and Capacity of Radio Links

This paper addresses the operation of radio links under mutual interference conditions, an important problem in spectrum management and radio link design. It introduces the capacity loss and isolation index as measures of effective use of radio links and radio frequency spectrum resources.     

Locating the two-median of a tree network with continuous link demands

Typical formulations of thep-median problem on a network assume discrete nodal demands. However, for many problems, demands are better represented by continuous functions along the links, in addition to nodal demands. For such problems, optimal server locations need not occur at nodes, so that algorithms of the kind developed for the discrete demand case can not be used. In this paper we show how the 2-median of a tree network with continuous link demands can be found using an algorithm based on sequential location and allocation. We show that the algorithm will converge to a local minimum and then present a procedure for finding the global minimum solution.