The SHARC framework for data quality in Web archiving

Web archives preserve the history of born-digital content and offer great potential for sociologists, business analysts, and legal experts on intellectual property and compliance issues. Data quality is crucial for these purposes. Ideally, crawlers should gather coherent captures of entire Web sites, but the politeness etiquette and completeness requirement mandate very slow, long-duration crawling while Web sites undergo changes. This paper presents the SHARC framework for assessing the data quality in Web archives and for tuning capturing strategies toward better quality with given resources. We define data quality measures, characterize their properties, and develop a suite of quality-conscious scheduling strategies for archive crawling. Our framework includes single-visit and visit?Crevisit crawls. Single-visit crawls download every page of a site exactly once in an order that aims to minimize the ??blur?? in capturing the site. Visit?Crevisit strategies revisit pages after their initial downloads to check for intermediate changes. The revisiting order aims to maximize the ??coherence?? of the site capture(number pages that did not change during the capture). The quality notions of blur and coherence are formalized in the paper. Blur is a stochastic notion that reflects the expected number of page changes that a time-travel access to a site capture would accidentally see, instead of the ideal view of a instantaneously captured, ??sharp?? site. Coherence is a deterministic quality measure that counts the number of unchanged and thus coherently captured pages in a site snapshot. Strategies that aim to either minimize blur or maximize coherence are based on prior knowledge of or predictions for the change rates of individual pages. Our framework includes fairly accurate classifiers for change predictions. All strategies are fully implemented in a testbed and shown to be effective by experiments with both synthetically generated sites and a periodic crawl series for different Web sites.     

On some weight functions admitting (0, 2) quadrature formulae with a high algebraic degree of precision

The purpose of this paper is to find a class of weight functions μ for which there exist quadrature formulae of the form (1) $$\int_{ - 1}^1 {\mu (x) f(x) dx \approx \sum\limits_{k = 1}^n {(a_k f(x_k ) + b_k f''(x_k ))} }$$ , which are precise for every polynomial of degree 2n.     

Synthesis and structure of large single crystalline silver hexagonal microplates suitable for micromachining

We report a simple one-step synthesis method of large single crystalline Ag (111) hexagonal microplates with sharp edges and a size of up to tens of microns. Single silver crystals were produced by reduction silver nitrate aqueous solution with 4-(methylamino)phenol sulfate. Scanning and transmission electron microscopy, energy-dispersive X-ray spectroscopy, selected area electron diffraction and optical microscopy techniques were combined to characterize the crystals. It is shown that the microplates can be easily dispersed and transferred as single objects onto different substrates and subsequently used as a high quality plasmonic starting material for micromachining of future nanocomponents, using modern top-down techniques like focused-ion beam milling and gas injection deposition.     

绿色能源与绿色工业(英文)

<正>A New AUsing the Modified Four Point Probe (Mo4PP) as a Tool for Monitoring Processing of Solar Cell Wafers 1 Modified Four Point Probe The aim of this report is to present and justify a new tool (Mo4PP) for Monitoring processing of solar cells.     

Catalytic activity of Fe/AC, obtained by impregnation of activated carbon in aqueous and non-aqueous media, to neutralize NO

The influence of the nature of the impregnating solutions media (aqueous or non-aqueous) on the forming of active phases is investigated in case of preparing iron catalysts, supported on activated carbon with respect to their catalytic activity in the reaction of NO reduction by CO. The catalysts are characterized by chemical analysis (AAS), BET surface area, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), magnetic susceptibility, and Mössbauer spectroscopy (MS). The catalytic investigations and TPD are carried out in a flow apparatus. Three peculiarities are observed with respect to this influence—the ratio between the separate iron species in different oxidation state of Fe species, which build up the catalytic active complexes (CAC), common participation of superficial groups of the carbon support and Fe components of the impregnating solutions as well as different dispersion of the active phase on the surface of the samples. As a result the highest catalytic activity was observed with the sample, obtained by impregnation with an aqueous solution, while with the other samples, obtained from organic solutions, the catalytic activity decreases in the order of: Methanol > Ethyl Ether > Acetone. It was assumed that the different catalytic activities are connected most probably with the process of forming of CAC during the process of preparation of the samples.     

Screening of elemental impurities in commercial detonation nanodiamond using sector field inductively coupled plasma-mass spectrometry

The quantitation of 55 elemental impurities in 15 commercial samples of detonation nanodiamond (DND), micron-sized diamond of high pressure/high temperature synthesis and detonation synthesis soot (DS) was achieved using a direct sector field ICP-MS analytical method. A set of 23 elements contributing more than 99.8 mass % of all impurities was selected and used as markers for the evaluation of DND purity. Obtained data were evaluated to identify important information on possible sources of nanodiamond contamination during purification, disaggregation, solubilisation or stabilisation of suspensions. Distinctive groups of elements (including Cr, Mn and S; Mo, W, V and Ti; Na, B and Si; Ca and Mg) occurring at elevated levels in DND can be readily visualised using radar plots, and can be related to the detonation synthesis (construction materials of explosion chamber, admixture in coolant, detonator type) and/or purification processes (type of oxidation process and reagents). The contaminant profile for each respective DND can be also considered as a fingerprint, characteristic for every producer and technology used. Results obtained also highlight how DND can be considered as effective collectors of various inorganic impurities from chemical reagents, glassware, sonotrode and other materials used during processing, including disaggregation and stabilisation of suspensions.     

Modeling participatory learning as a control mechanism

We discuss the participatory learning model originally introduced by Yager [IEEE Trans. Syst. Man Cybern. SMC-20 , 1229–1234 (1990)]. We analyze the learning mechanism as a stable control strategy. We show how the learning mechanism used in participatory learning can be expressed in the form of a fuzzy rule base. We use this rule base formulation to provide new learning rules. We modify the Widrow-Hoff rule to include a participatory learning mechanism. © 1993 John Wiley & Sons, Inc.     

互联网的业务融合及可信度研究

互联网融合多种业务过程中面临服务质量、信息安全和网络可信度等问题带来的挑战。实行实名制,层次结构,测量、监控与审计,流量规划和准入控制,地址空间扩充,网络可信度综合评价是有效的治理措施。从驻地网开始治理,使得每一个驻地网都有良好的品质,可为互联网提供良好的服务创造条件。     

Mechanochemical Synthesis and Characterization of Nanocrystalline Copper-Cobalt Ferrites

Nanocrystalline copper-cobalt ferrites with composition Cu_(1-x)Co_xFe_2O_4,where x = 0.2 and 0.8,were synthesized by mechanochemical treatment of co-precipitated precursors.The ferrite powders were characterized by XRD and Mossbauer spectroscopy.Results proved obtaining of spinel ferrites with crystallite size smaller than 10 nm.Increasing of crystallite size of samples with increasing of mechanochemical treatment duration was established,too.Catalytic properties of obtained ferrites were tested in reactions of oxidation of CO,methanol and dimethyl ether.High catalytic activity of nanocrystalline copper-cobalt ferrites toward CO and CH_3OH(about 100% conversions of CO and CH_3OH at 160 ℃)and moderate activity toward(CH_3)_2O oxidation were established.The results obtained revealed that the Co/Cu atomic ratio is an important factor determinant the behavior of catalysts toward methanol and DME oxidation.