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排序方式: 共有595条查询结果,搜索用时 15 毫秒
71.
Online social networks (OSN) are technology-enabled relationship tools in which a user creates a profile, connects to other individuals, and shares user-generated content with them. One of the many features OSN offer is the ability to post messages in the form of product and service recommendations. Although word-of-mouth research has examined this type of personal communication to intentionally influence consumer decisions, limited understanding exists regarding when a user acts upon a recommendation received from one of their contacts. In this study, we draw on relationship theories and research on trust to analyze the impact relationship characteristics and behaviors of the OSN contacts have on trust in the recommendation that subsequently leads a user to act on this OSN contact’s recommendation. The results of a survey of 116 OSN users showed that closeness, excessive posting behavior, and past recommendation experience have a positive impact on trust and intention to act on the recommendation. One characteristic of the relationships, that is, similarity, however, does not affect recommendation trust in the context of OSN. The findings enhance our understanding of relationships and their defining characteristics in OSN. The results also provide insights into how companies might leverage OSN in their marketing efforts. 相似文献
72.
Johanna Senatore 《Computer aided design》2008,40(5):595-603
This article introduces a method to estimate geometric error during flank milling of a ruled surface. The various positioning schemes developed by researchers are intended to reduce this geometric error in order to mill with larger sized milling cutters while respecting the tolerance interval. There are two trends in positioning: either positioning is simple and right from the start it is easy to determine design of the maximum allowed milling cutter radius, or positioning is complex and determination of the maximum milling cutter dimensions can only be conducted after digital calculations of the error. It will then be necessary to choose another milling cutter radius and recommence the positioning procedure and error calculation in order to validate the tool. In the present study, a method to estimate error in the scope of complex positioning is presented. The aim is to be capable of choosing a maximum cutting tool radius that respects the tolerance interval. 相似文献
73.
Johanna Nellen Kai Driessen Martin Neuhäußer Erika Ábrahám Benedikt Wolters 《Information Systems Frontiers》2016,18(5):927-952
In this paper we address the safety analysis of chemical plants controlled by programmable logic controllers (PLCs). We consider a specification of the control program of the PLCs, extended with the specification of the dynamic plant behavior. The resulting hybrid models can be transformed to hybrid automata, for which advanced techniques for reachability analysis exist. However, the hybrid automata models are often too large to be analyzed. We propose two counterexample-guided abstraction refinement (CEGAR) approaches to keep the size of the hybrid models moderate. 相似文献
74.
Fabian
Prasser Johanna Eicher Helmut Spengler Raffael Bild Klaus A. Kuhn 《Software》2020,50(7):1277-1304
The race for innovation has turned into a race for data. Rapid developments of new technologies, especially in the field of artificial intelligence, are accompanied by new ways of accessing, integrating, and analyzing sensitive personal data. Examples include financial transactions, social network activities, location traces, and medical records. As a consequence, adequate and careful privacy management has become a significant challenge. New data protection regulations, for example in the EU and China, are direct responses to these developments. Data anonymization is an important building block of data protection concepts, as it allows to reduce privacy risks by altering data. The development of anonymization tools involves significant challenges, however. For instance, the effectiveness of different anonymization techniques depends on context, and thus tools need to support a large set of methods to ensure that the usefulness of data is not overly affected by risk-reducing transformations. In spite of these requirements, existing solutions typically only support a small set of methods. In this work, we describe how we have extended an open source data anonymization tool to support almost arbitrary combinations of a wide range of techniques in a scalable manner. We then review the spectrum of methods supported and discuss their compatibility within the novel framework. The results of an extensive experimental comparison show that our approach outperforms related solutions in terms of scalability and output data quality—while supporting a much broader range of techniques. Finally, we discuss practical experiences with ARX and present remaining issues and challenges ahead. 相似文献
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Concepcion Romero & Johanna Bakker 《International Journal of Food Science & Technology》2000,35(1):129-140
Summary It was found that the reaction between malvidin 3-glucoside and added pyruvic acid (PA), leading to the formation of vitisin A in model wine solutions, was not prevented by the addition of either acetaldehyde (A) or several organic acids. The acylated forms of vitisin A (3-acetylvitisin A and 3- p -coumarylvitisin A) were formed through the interaction of malvidin 3-acetylglucoside and malvidin 3- p -coumarylglucoside. Disappearance of the three main anthocyanins (malvidin 3-glucoside, malvidin 3-acetylglucoside and malvidin 3- p- coumarylglucoside) from the model wine with time followed first order kinetics. Acetaldehyde had the effect of increasing the total amount of these losses but producing smaller amounts of vitisin A. During ageing model solutions developed some browness. The brownest solution was obtained without A and a reduced rate of browning was found in the presence of A. This latter result can be explained by the assumption of a superimposition of a blueing effect upon reactions of A with anthocyanins. In the presence of PA the formation of vitisin A compounds gave an intermediate colour, contributing a reddish hue to the solution. A good correlation (r2 = 0.96) between the percentage of vitisin A, of the total anthocyanins and the hue angle was observed. The addition of large amounts of organic acids that are normally found in wine into the model solutions did not lead to the formation of new anthocyanins. The linear loss of PA in all model systems indicates that a first order reaction occurs and 35.35 times more PA than total anthocyanin was lost to form the new compounds. 相似文献
77.
Menno A. van der Meer Joamms E. Robbers Johanna E. van der Wal 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1987,185(6):461-467
Summary Booth's method for the spectrophotometric determination ofß-carotene gives reliable results, but the extraction method is very laborious and tedious. Removal of the acetone from the extract and elution of the acetone-free extract on the adsorption column also require much time and attention. The authors describe the modifications made to these three parts of Booth's method for the determination of carotene. The simultaneous application of Booth's original method and of the modified method to samples of carrots, five leafy vegetables and four brassicas gave, in general, corresponding results. With brassicas a tendency was observed for the modified method to yield lower carotene contents. Using the modified method, with pureß-carotene added to samples of carrots and spinach, the authors found recoveries of 98%–100% and 86%–88% respectively.
Modifikationen der spektrophotometrischenß-Carotin-Bestimmung nach Booth in Gemüse
Zusammenfassung Die Ergebnisse der spektrophotometrischenß-Carotin-Bestimmung nach Booth sind zuverlässig, aber die damit verbundene Extraktionsmethode ist arbeitsintensiv und strapaziös. Auch das Entfernen von Aceton aus dem Extrakt und das Eluieren des acetonfreien Extrakts auf der Säule erfordert viel Zeit und Aufmerksamkeit. Die Autoren beschreiben die von ihnen angebrachten Modifikationen dieserß-Carotin-Bestimmung in den drei Stufen. Die gleichzeitige Anwendung der ursprünglichen Methode nach Booth und deren Modifikation brachte bei Karotten, fünf Blattgemüsen und vier Kohlarten im allgemeinen ähnliche Ergebnisse. Bei den Kohlarten war die Tendenz zu beobachten, daß mit der modifizierten Methode dieß-Carotingehalte etwas niedriger waren. Die modifizierte Methode hatte eine Rückgewinnungsquote von 98–100% bzw. 86–88% bei einem Zusatz von reinemß-Carotin zu Karotten- und Spinatproben.相似文献
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