Analysis of autocatalytic networks in biology

Autocatalytic networks, in particular the glycolytic pathway, constitute an important part of the cell metabolism. Changes in the concentration of metabolites and catalyzing enzymes during the lifetime of the cell can lead to perturbations from its nominal operating condition. We investigate the effects of such perturbations on stability properties, e.g., the extent of regions of attraction, of a particular family of autocatalytic network models. Numerical experiments demonstrate that systems that are robust with respect to perturbations in the parameter space have an easily “verifiable” (in terms of proof complexity) region of attraction properties. Motivated by the computational complexity of optimization-based formulations, we take a compositional approach and exploit a natural decomposition of the system, induced by the underlying biological structure, into a feedback interconnection of two input–output subsystems: a small subsystem with complicating nonlinearities and a large subsystem with simple dynamics. This decomposition simplifies the analysis of large pathways by assembling region of attraction certificates based on the input–output properties of the subsystems. It enables numerical as well as analytical construction of block-diagonal Lyapunov functions for a large family of autocatalytic pathways.     

QSAR结合人工神经网络方法研究取代芳烃分子结构与Na-K-ATP酶活性

运用函数连接型神经网络研究 3 8种取代芳烃化合物的分子结构—毒性的定量构效关系 (QSAR) ,计算结果与MLR计算结果比较 ,前者比后者好。与实验结果的线性拟合相关系数 ,FLN所得结果为 0 9561～ 0 9996,MLR所得结果为 0 869～ 0 965。     

多值属性关联规则的理论基础

关联规则的研究主要集中在发现高效的算法,而该文基于形式概念分析讨论了多值属性关联规则发现的框架,指出最大频繁项目集由最大频繁闭合项目集唯一确定。     

仿真可信性的研究综述

从概念性研究、技术方法和工程应用等三个方面综述了仿真可信性研究的发展。．     

一个双重优化的IP-DiffServ定量QoS管理实现机制*

提出了IP-DiffServ 定量QoS 实现机制, 它通过在网络层实施业务量工程实现了业务类选择路由的优化, 通过在业务层实施业务计划实现了用户业务选择业务类的优化。它不但可以在DiffServ 机制下给用户业务应用提供定量QoS 保证, 而且可以提高网络资源的使用效率以及提高用户业务和选择路由的性能价格比。实验结果很好地证明了该机制的优点。     

Biases in quantitative judgements

This article illustrates the biases that can occur in making quantitative judgements. The mechanisms that produce the biases are described. Ways are suggested to avoid some of the biase, but it is not possible to avoid them all.     

Quantitative characterization of nanoprecipitates in irradiated low-alloy steels: advances in the application of FEG-STEM quantitative microanalysis to real materials

The characterization of the solute-enriched features (clusters or nanoprecipitates in irradiated low-alloy steels) requires extremely high spatial and elemental resolution, previously necessitating analysis using atom probe field-ion microscopy. In this investigation, field-emission gun-scanning transmission electron microscope (FEG-STEM) quantitative energy dispersive X-ray (EDX) microanalysis (spectrum imaging) has been applied to the characterization of the irradiation-induced nanoprecipitates in a low-alloy forging steel. Refinements in the EDX data have been possible via the application of multivariate statistical analysis (MSA) to the spectrum images, resulting in significantly reduced noise in the images. Most importantly, MSA permitted the clear identification of other elements in these Ni-enriched nanoprecipitates—including Mn and Cu. The processed X-ray spectrum images also provided direct evidence of the preferential formation of these irradiation-induced features along pre-existing dislocations within the steel, as well as the formation of intragranular nanoprecipitates. This research has provided the first direct X-ray spectrum images of irradiation-induced nanoprecipitates in high Ni A508 Gr4N forging steel, and has demonstrated the significant improvements attainable though the application of MSA techniques to the spectrum images. These results independently confirmed the analyses of the Ni-enriched nanoprecipitates previously conducted by 3D-APFIM, with the performance of the FEG-STEM/EDX technique shown to be comparable to that of the 3D-APFIM technique.     

ITO粉的Rietveld全谱图拟合定量相分析

对ITO粉样品用Rietveld全谱图拟合法进行了定量相分析，该样品由立方晶型的In2O3和少量的四方晶系的SnO2所组成。In2O3和SnO2质量百分含量分别为94．23％和5．77％。结果表明，用Rietveld法进行了定量相分析是非常有效和准确的。     

参数自调整模糊控制器在中央空调控制系统中的应用

针对典型的非线性、时变、滞后系统——中央空调温度控制过程，在分析量化因子和比例因子对系统性能影响的基础上，本文提出了参数自调整模糊控制算法。仿真表明，参数自适应控制器的控制性能优于常规模糊控制器。     

Using group communication to monitor web-based group learning

Abstract  In a web group-learning environment, students must communicate with other group members on the Internet to accomplish group projects and share knowledge. Communication is likely to affect performance and so analysing the relationship between communicative relationships and group performance may help teachers to monitor groups effectively. Certain tasks are necessary to perform such an analysis — recording group communication, extracting communication relationships and determining the relationship between group communication and group performance. This study developed a method for determining relationships and rules for predicting performance to enable teachers to take act appropriately according to the predicted performance of the group. Four group performance indicators are considered — average grades within a group, project grade, frequency of resource-sharing and drop-out rate. Experimental results are presented, concerning the application of the methodology to a web class of 706 students, divided into 70 groups. The experimental results show that group communication patterns significantly affect group performance.