Sensitive glasslike sol–gel materials suitable for environmental light sensors

New sol–gel based sensitive materials able to detect moderate doses of UV, Vis and near IR radiations have been designed, prepared and characterised. These glasslike detectors are respectively composed by four different sols of inorganic and hybrid organic–inorganic silica matrixes. The sols were prepared from alkoxide (TEOS) and alkylalkoxide (GLYMO) precursors with molar ratios 1:0, 1:1, 1:4 and 0:1, respectively. All the sols were doped with an organic photochromic dye (spiropyran). The detectors characterisation was carried out by means of exposures to natural light under different light intensities (100–3000 lx). The highest sensitivity against the light radiation was found for sols with molar ratio TEOS:GLYMO of 1:1. The time response of detectors is found at about 10 min and their life time is roughly 4 months at least. Moreover, the detectors show good optical reversibility. These sensitive glasslike materials have been designed to be applied for preservation of historical goods. They can detect and evaluate dangerous light doses for the proper conservation conditions of historical materials, which are sensitive or moderately sensitive against light radiation (<600 lx).     

水体中对氯苯酚的电化学降解研究

目的研究电化学氧化法对水体中的对氯苯酚的降解效果.方法以对氯苯酚溶液为模型污水,通过静态试验研究支持电解质浓度、初始质量浓度、外加电压、初始pH值、不同的反应体系等对电化学氧化降解对氯苯酚效果的影响.结果实验表明处理对氯苯酚污水的较佳条件是:外加电压为5V,电解质浓度为0.03 mol/L,初始pH值为2.9,极间距为15 mm.对氯苯酚的降解效率可达80%以上,初始pH值对对氯苯酚的降解效果影响较大.结论电化学氧化法能够有效降解模型污水中的对氯苯酚,加强传质可有效提高降解效率,较低的操作电压,有助于降低处理成本.     

逐段决定马尔可夫过程及其在风险中的应用

着重介绍了PDMP主要理论的研究进展．包括PDMP模型的一般化,PDMP生成元理论的推广,跳机制的状态空间跳测度刻画,微分公式的推广以及新结果在一类风险模型破产理论中的应用等．     

Banach空间中广义压缩映射的迭代逼近法

讨论了广义压缩映射的具误差的Ishikawa迭代和具误差的Mann迭代程序在实光滑Banach空间及任意Banach空间中的收剑性问题,得出的结论推广了以前同类问题的一些结果.     

如何提高数控线切割加工的稳定性

详细分析了在快走丝数控线切割机床操作过程中,电加工参数、机械参数、电极丝、切割方向、切割液、导电块等因素对线切割加工的影响,以及如何处理和排除这些故障,以提高线切割机床加工的稳定性,保证加工零件的表面质量、尺寸精度和加工效率。     

考虑粘性泥沙运动的黄河口二维水沙输移数学模型

为研究黄河口的水沙输移规律,采用基于无结构三角网格下的有限体积法建立了平面二维水沙数学模型.模型中分别采用不同方法处理粘性和非粘性沙的输移源项,并引入经验证的粘性沙输移源项改进公式.采用已有的概化水槽冲淤试验资料对模型进行了验证,然后应用于1982年6月至1983年5月期间黄河口水沙输移的数值模拟,计算得到的潮位过程及冲淤量与实测资料符合较好,结果表明模型能够较好地模拟考虑粘性沙运动的黄河口非均匀沙不平衡输移.最后比较了不同泥沙输移源项处理方式对模拟结果的影响,计算表明在黄河口水沙输移数值模拟中需要采用非均匀沙模型并同时考虑粘性和非粘性泥沙的输移.     

对称稳定过程的局部泛函重对数律

给出了对称稳定过程的局部泛函重对数律，并推广了布朗运动的结果，也为对称马氏过程局部泛函重对数律的研究作了点探索。     

房地产投资项目可行性报告中敏感性分析的自动化辅助系统的设计

本文提出了在房地产投资项目可行性分析报告中,进行敏感性分析的自动化辅助系统的设计方法,这一系统使用Excel软件和利用VBAForExcel语言编程,能使用户通过简单的操作步骤输入必要的参数,系统自动完成敏感性分析的全部工作．     

Ultrasonic Sealing of Flexible Packaging Films – Principle and Characteristics of an Alternative Sealing Method

The closure process for packaging is a key process. It ensures the protective function of packaging and assures the packaged goods a long life. In this context, efficient and reliable sealing processes are essential for the production of sustainable packages. In this paper, several characteristics of the ultrasonic sealing process will be discussed and accompanied by experimental results. The introduction provides an insight into the ultrasonic sealing process, its heating mechanisms and the process steps. A comparison is made with conduction sealing. Furthermore, basic principles of heating and energy dissipation are related to the influences of the sealing parameters on the seam strength. The experimental studies were carried out on typical packaging films, such as polyamide‐polyethylene laminates. The seam strength in ultrasonic sealing is compared with that in conductive sealing. A lower seam strength was found for ultrasonic sealing in all the tested films. Furthermore, the sealing behaviour of the packaging films contaminated with different kinds of foods was analysed for both sealing methods. Although the ultrasonic sealing method has marginal advantages for bulk materials such as wheat flour, conduction sealing was shown to be better for other products. A comparison of the energy consumption during the ultrasonic and conduction sealing verified the advantages of ultrasonic sealing. In particular for thick packaging films, the amount of energy required for bonding is significantly lower than for conduction sealing. In summary, this paper provides a survey of the characteristics of the ultrasonic sealing method in packaging applications – its advantages and limitations. Copyright © 2011 John Wiley & Sons, Ltd.     

The two-regime method for optimizing stochastic reaction–diffusion simulations

Spatial organization and noise play an important role in molecular systems biology. In recent years, a number of software packages have been developed for stochastic spatio-temporal simulation, ranging from detailed molecular-based approaches to less detailed compartment-based simulations. Compartment-based approaches yield quick and accurate mesoscopic results, but lack the level of detail that is characteristic of the computationally intensive molecular-based models. Often microscopic detail is only required in a small region (e.g. close to the cell membrane). Currently, the best way to achieve microscopic detail is to use a resource-intensive simulation over the whole domain. We develop the two-regime method (TRM) in which a molecular-based algorithm is used where desired and a compartment-based approach is used elsewhere. We present easy-to-implement coupling conditions which ensure that the TRM results have the same accuracy as a detailed molecular-based model in the whole simulation domain. Therefore, the TRM combines strengths of previously developed stochastic reaction–diffusion software to efficiently explore the behaviour of biological models. Illustrative examples and the mathematical justification of the TRM are also presented.