基于时间Petri网的制造过程模型研究

分析了时间Petri网的激发规则、托肯可用时间和抑制弧等特性,以及制造过程中随机故障的特征。提出不同的时间关联方式对应的多种建模方法,考虑不同的故障发现模式、不同的作业处理策略,建立相应的单机制造过程模型。在此基础上采用模块化和层次化方法可以构建复杂制造过程的时间着色Petri网模型,并可以转换成仿真模型,进一步分析随机机器故障对制造过程性能的影响。

基于.NET的开放网格服务基础结构研究

本文首先介绍了OGSI的基本概念，接着讨论了Web服务与OGSI 的关系。最后阐述了一个依托.NET技术实现的OGSI原型率统并介绍一些现有的开发工具。

基于.NET的企业应用框架

介绍了.NET框架的基本概念、特点及优势。接着讨论了企业分层应用模型的分层原则、分层方法、层设计原则和交互模式。根据企业分层应用模型提出了一个典型的三层企业服务应用方案， 阐述了如何依托.NET技术实现该企业分层应用模型。

面向复杂制造过程质量的模糊Petri网预测及诊断方法研究

在复杂制造过程中，存在质量异常预测及诊断能力弱、智能化程度低、效率低等问题。如何针对制造过程质量问题特点采用合适的预测与诊断方法，满足日益提高的过程自动化水平的要求，是该领域研究人员面临重要的亟待解决的问题。 由于模糊Petri网是模糊集理论与Petri网理论有机结合的一种网络理论，其突出优势在于知识表示、推理和处理模糊信息的能力; 目前，尽管模糊Petri网已有成功的应用案例，但仍存在某些不足，需不断地改进与完善。因此，对模糊Petri网理论方法的研究，有利于提高其知识表示能力、模糊动态推理能力、推理结果可靠性与准确性等，对模糊Petri网理论的广泛应用具有推动作用。 本文以制造过程质量问题的预测与诊断为研究和应用背景，对模糊Petri网预测与诊断方法的研究为主线，以研发的系统为辅助分析工具，重点从方法的层面上对模糊Petri网理论进行了研究和探讨。旨在进一步完善模糊Petri网相关理论，并应用于制造过程质量问题的解决，提高过程的质量监控能力、事故预防能力、缩短故障原因查找周期、提高定位准确性及可靠性奠定方法基础。 针对制造过程质量预测与诊断问题特点，在广泛阅读相关文献并深入探索的基础上，对模糊Petri网理论方法进行了较深入的研究和探讨，重点解决了以下问题： 1）模糊Petri网自动建模方法：对模糊Petri网理论研究的基础和前提是建立模糊Petri网模型。为解决当前模糊Petri网建模效率低、工作量大、易出错等问题，本文提出了模糊Petri网的自动建模方法。该方法的提出，易于保证知识库与模型库更新的同步和一致，提高了建模效率，避免了建模的人为失误。 2) 模糊Petri网参数确定：模型建立后，为实现可靠有效地推理，需进行相关参数的确定。提出了确定模糊Petri网的初始库所token的方法。通过模糊统计的方法来获得模糊token，减少确定token时的主观臆断性和不一致性，为物理量与模糊token的实时转换提供了技术支持。由于构建符合客观实际的、连续的隶属函数是确定模糊token的前提条件，本文提出采用最小二乘拟合来构造模糊隶属函数方法。该方法简单，拟合能力强，人工干预少。由于变迁阈值影响推理的正确性及可靠性，这里对阈值设定进行了初步探讨。阈值设定越高，预测及诊断的漏报率越高；反之，误报率越高。给出了阈值设定的总代价计算式，阈值选择的目标是使总代价最小。 在建立了模糊Petri网模型、确定了相关参数后，便可对异常事件进行预测及诊断推理。 3）模糊Petri网预测方法：对预测模式进行了分类与定义，便于对不同模式下进行预测分析。提出了改进的FPN四种基本推理模型，通过禁止弧的引入，避免了激发过的变迁反复被激发，减少不必要的计算，实现了推理与模型结构的一致性。从而提高了推理效率和基于规则系统的响应能力。 4）模糊Petri网诊断方法：给出了一种模糊Petri网诊断推理方法。该方法充分利用模糊Petri网自身的结构与数学特性这一突出优势，实现了并行推理。以矢量计算方式获得中间库所能力，取代了常规的搜索方式，提高了推理效率。通过引入人机交互的处理策略，减少了模糊Petri网的复杂性及规模。指出在实践中，推理方法的效率、成本及实际的应用效果， 在重要性方面，要远大于方法自身的运算效率。 5）模糊着色Petri网推理方法：在建模复杂大型系统时，为解决模糊Petri网存在模型空间过大，模型数据结构松散等问题，提出了FCPN并行推理方法及FPR与FCPN模型转换算法。提出的FCPN与现有方法的主要区别在以下方面：首先，算法实现变迁的单次激发，避免推理激发变迁的重复计算。其次，某个使能变迁前集库所中token在该变迁激发后并不移除，符合实际推理情况。此外，通过输入/输出关联矩阵计算迭代，实现了并行推理。 最后，以一典型制造过程—埋弧自动焊接过程质量问题的预测和诊断为例，来说明模糊Petri网方法的实际应用。通过系统的实现，验证了相应方法是可行的。通过模糊Petri网的预测及诊断推理，便于实现质量异常的分析、预警、处理、过程控制及数字化管理，为生产策略的调整、纠正措施的采取提供了决策依据，加快了系统响应速度。 本文研究工作重点围绕模糊Petri网理论方法展开，虽以制造过程质量问题的预测与诊断为研究和应用背景，但并不局限于该领域，是属于具有一般性的共性方法。因此，所开展的方法研究工作具有良好的科研价值和广泛的应用前景。

Stainless-steel-net-supported zeolite NaA membrane with high permeance and high permselectivity for oxygen over nitrogen

A stainless-steel net is used to support a zeolite NaA membrane synthesized using a 'seeded-growth' method. The zeolite and stainless-steel net are tightly integrated (see Figure), showing large-scale order and high mechanical stability. High oxygen permeance and high permselectivity for O-2 over N-2 (about 7) is demonstrated.

The Net and the Self: Colliding Views of Individuality and Nationhood in the Pre-Devolutionary plays of Mark Jenkins and Ed Thomas

Owen, Roger, 'The Net and the Self: Colliding Views of Individuality and Nationhood in the Pre-Devolutionary plays of Mark Jenkins and Ed Thomas', In: 'Cool Britannia: British Political Drama in the 1990s', Rebecca D'Mont? and Graham Saunders (eds), (Basingstoke: Palgrave Macmillan), pp.158-175, 2007 RAE2008

Dafydd ap Gwilym.net

Edwards, Huw, et al., Golygiad newydd o 33 o gerddi Dafydd ap Gwilym, a chyfraniad 9,830 o eiriau i'r rhagymadrodd ar 'Y Cyd-destun llenyddol' (2007)

D. Antonii Gomezii, in Academia Salmanticensi Juris Civilis Primarii Professoris, Variae resolutiones juris civilis, communis, et regii : tomis tribus distinctae : quorum I Ultimarum Voluntatum, II Contractuum, III Delictorum, materias continet

Editio novissima cui praeter Annotationes Emanuelis Suarez a Ribeira, accesserunt Illustrationes, sive Additiones Joannis de Ayllon Laynez in fine cujusque Capitis appositae, cum Indice Generali.

Interaction strengths and net effects in food web models

Understanding how dynamic ecological communities respond to anthropogenic drivers of change such as habitat loss and fragmentation, climate change and the introduction of alien species requires that there is a theoretical framework able to predict community dynamics. At present there is a lack of empirical data that can be used to inform and test predictive models, which means that much of our knowledge regarding the response of ecological communities to perturbations is obtained from theoretical analyses and simulations. This thesis is composed of two strands of research: an empirical experiment conducted to inform the scaling of intraspecific and interspecific interaction strengths in a three species food chain and a series of theoretical analyses on the changes to equilibrium biomass abundances following press perturbations. The empirical experiment is a consequence of the difficulties faced when parameterising the intraspecific interaction strengths in a Lotka-Volterra model. A modification of the dynamic index is used alongside the original dynamic index to estimate intraspecific interactions and interspecific interaction strengths in a three species food. The theoretical analyses focused on the effect of press perturbations to focal species on the equilibrium biomass densities of all species in the community; these perturbations allow for the quantification of a species total net effect. It was found that there is a strong and consistent positive relationship between a species body size and its total net effect for a set of 97 synthetic food webs and also for the Ythan Estuary and Tuesday Lake food webs (empirically described food webs). It is shown that ecological constraints (due to allometric scaling) on the magnitude of entries in the community matrix cause the patterns observed in the inverse community matrix and thus explain the relationship between a species body mass and its total net effect in a community.

Hydraulic redistribution of soil water by roots affects whole-stand evapotranspiration and net ecosystem carbon exchange.

*Hydraulic redistribution (HR) of water via roots from moist to drier portions of the soil occurs in many ecosystems, potentially influencing both water use and carbon assimilation. *By measuring soil water content, sap flow and eddy covariance, we investigated the temporal variability of HR in a loblolly pine (Pinus taeda) plantation during months of normal and below-normal precipitation, and examined its effects on tree transpiration, ecosystem water use and carbon exchange. *The occurrence of HR was explained by courses of reverse flow through roots. As the drought progressed, HR maintained soil moisture above 0.15 cm(3) cm(-3) and increased transpiration by 30-50%. HR accounted for 15-25% of measured total site water depletion seasonally, peaking at 1.05 mm d(-1). The understory species depended on water redistributed by the deep-rooted overstory pine trees for their early summer water supply. Modeling carbon flux showed that in the absence of HR, gross ecosystem productivity and net ecosystem exchange could be reduced by 750 and 400 g C m(-2) yr(-1), respectively. *Hydraulic redistribution mitigated the effects of soil drying on understory and stand evapotranspiration and had important implications for net primary productivity by maintaining this whole ecosystem as a carbon sink.

Drawing the net: internet identification, internet use, and the image of internet users

Theory and research suggest that Internet identification may account for some of the gender divide in Internet use. Internet identification is a type of domain identification, and is inherently bound with images of those who use the Internet, a domain traditionally conceived as masculine. Combining the “draw an Internet user” test with an Internet identification scale, this study tests two hypotheses: participants drawing gender-concordant images will (i) identify with and (ii) use the Internet more than those drawing gender-discordant images. Participants were 371 students (121 males, 250 females) from three universities in the United Kingdom and Australia. The need to challenge masculinized images of the Internet is discussed.