Security properties: two agents are sufficient

We consider an important family of cryptographic protocols and a class of security properties which encompasses secrecy and authentication. We show that it is always sufficient to consider a bounded number of agents b (b = 2 for secrecy properties for example): if there is an attack involving n agents, then there is an attack involving at most b agents.     

Direct Conversion of FM Magnetic Tape Data into Digital Form

A system is described for decoding frequency-modulated magnetic tape data directly into digital form suitable for input to a digital computer. Included in the system is a very precise method used to compensate for flutter errors. The bypassing of standard demodulation, filtering, and analog-to-digital conversion permits a significant improvement in signal-to-noise ratio. This type of system is most advantageous when reproducing data from magnetic decks whose signal-to-noise ratios cannot be reliably expected to remain at a satisfactory level. Using electrocardiograms, it has been demonstrated that a real gain in the detection of low-amplitude waveforms can be achieved with this system as compared to conventional reproducing.     

Development and application of a measure of students' college experiences.

Describes the College Experience Inventory (CEI), developed by the authors to assess student experiences during college. The CEI was administered to 743 university seniors at the end of their college careers. Analyses of the Ss' responses resulted in 12 CEI factors that were found to be significantly related to life-history data collected 4 yrs prior to the administration of the CEI. Subgroups of Ss based on life history were meaningfully differentiated by the CEI. Longitudinal patterns of experiences (paths) followed by Ss through their 4 yrs of college could be identified. Ss who selected one path to the exclusion of others were found to differ on selected academic criteria. Results indicate that the CEI has potential for use in student counseling and university placement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Oxidation of Na2SO4 coated Ni-20Cr-2ThO2

The Na₂SO₄-induced oxidation of Ni-20Cr-2ThO₂ has been studied at 900° and 1000°C in 150 torr O₂. A rapid weight-gain period, corresponding to NiO formation occurs after a short incubation period. The duration of the rapid weight gain stage persists for about 2 h and terminates with the development of a continuous Cr₂O₃ internal layer. Subsequent oxide formation is extremely slow, similar to that reported for normal oxidation of TD-NiCr. Formerly Formerly     

Zerstörungsfreie Prüfungen bei Betrieb und Instandhaltung von Chemieanlagen

Non-destructive testing in operation and maintenance of chemical plant . Non-destructive tests performed in chemical plant while it is in operation or standing idle are intended to give the plant operator the information on the state of the plant that is needed to ensure safety and availability. The scope of such tests and how often they are carried out depend on the condition of the plant and on the weaknesses that have been found in the course of time. The following are described as special examples of the versatile use of non-destructive test methods: (a) thermographic and ultrasonic checking of the condition of a rotary furnace; (b) observation of spherical ammonia containers to ensure early recognition of cracking; (c) detection of leaks in high pressure plant items having corrosion resistant linings; (d) metallography of structural element subjected to heavy loads for long periods at elevated temperatures; (e) wall thickness measurement of heat exchanger tubes; (f) on-site gamma radiation analysis of metallic materials with an portable RFA device.     

A general formula for the variance of Cohen's weighted kappa.

Suggests that J. Cohen's weighted kappa (see record 1969-00069-001) is actually a bilinear permutation statistic and the needed variance term can be obtained under the assumption that the contingency table categorizing the rater responses has fixed marginal frequencies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Untersuchungen zur Verhütung von Transportschäden bei anfälligen Tropenholzarten

Zusammenfassung Rundholzabschnitte junger B?ume von acht hellfarbigen, anf?lligen Holzarten wurden in Nigeria am F?llort mit zwei Holzschutzmitteln (Kombinationen eines ?ligen Insektizides mit einem Fungizid sowie einer insektizid und fungizid wirkenden Wasseremulsion) vorbeugend geschützt, nach Europa verschifft und nach ihrer Ankunft in Reinbek begutachtet. Die Proben wiesen sowohl auf der Oberfl?che als auch im Innern unterschiedliche Verf?rbungen auf, am st?rksten bei Ilomba, am geringsten bei Limba und Abachi. Die Verf?rbungen entstanden durch Pilze und durch anorganische Einflüsse. Ferner lag meist leichter Befall durch holzzerst?rende Pilze vor. Beide Schutzmitteltypen übten eine deutliche Schutzwirkung aus, die jedoch h?ufig auf eine dünne Randzone beschr?nkt blieb. Von Bedeutung waren w?hrend des Transportes aufgetretene Risse, durch die ein Befall des Holzinnern erm?glicht wurde. Sie traten am intensivsten bei Ilomba, am wenigsten bei Abachi, Alstonia und Okwen auf. Insektenbefall lag nicht vor, was u. a. auf die fortgeschrittene Jahreszeit zurückzuführen ist.—Aus den Ergebnissen werden Folgerungen für die Praxis gezogen.

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Investigations on the prevention of transport damages at susceptible tropical wood species

Summary Cuttings of young trees of eight light-coloured, susceptible wood species were treated prophylactically in Nigeria with two wood preservatives (I. various combinations of an oily insecticide and a fungicide, II. water emulsion with insecticides and fungicides in different concentration). They were shipped to Europe and evaluated after arrival. The samples showed discolourations to different extents both on the surface and inside; they were severe in Ilomba and less marked in Limba and Abachi. The discolourations were caused not only by fungi but also by inorganic influences. Furthermore, a slight attack by wood-destroying fungi could be observed in all species except Limba, Both preservatives had a distinct protective effect which, however, was restricted mainly to a small outer zone. Cracks which developed during the transport were important, since they enabled an attack and deterioration of the untreated inner parts. There were many cracks in Ilomba and only some in Abachi, Alstonia, and Okwen. Insect damage was not present which is due mainly to the late season. The results are discussed in relation to practical consequences.

     

Growth mechanisms of grain boundary allotriomorphs in Al-4Pct Cu at high homologous temperatures: Interfacial vs direct volume diffusion

The lengthening and thickening kinetics of θ allotriomorphs in Al-4 pet Cu were measured at 350°, 400°, and 450°C. Three different analyses all indicated that interfacial diffusion (i.e., a right angle collector plate mechanism) was the predominant growth mechanism at 350° and 400°C, but that volume diffusion directly to the growing allotriomorphs made a significant contribution to growth at 450°C. Using the data of this and previous investigations one may conclude that volume diffusion of solute directly to the allotriomorph does not contribute noticeably to growth belowT/T (solidus) = 0.78, plays a substantial but still a minority role atT/T (solidus) = 0.84 and 0.90 and becomes the major contributor atT/T (solidus) ≥ 0.91 when the matrix is fee.     

Beiträge zur Kinetik der Kieselsäurereduktion

Beschreibung einer Meβanordnung zur Erfassung des Einflusses veränderter Transportwege des Sauerstoffs im flüssigen Metall bei der Reduktion einer festen Oxidprobe. Untersuchung der Reduktionskinetik reiner fester Kieselsäure in kohlenstoffgesättigten Nickelschmelzen im Temperaturbereich von 1410 bis 1710°C. Aussagen über den geschwindigkeitsbestimmenden Schritt an Hand von Versuchen mit Siliziumgehalten der Schmelze von 0,01 bis 18,2Gew.-% und Gasdrücken von < 10^–2 bis 370 Torr. Vergleichsversuche zur Kieselsäurereduktion mit kohlenstoffgesättigten Eisen- und Kupferschmelzen. Erörterung zur Übertragbarkeit der Versuchsergebnisse auf Betriebsverfahren.     

Fleckenbildungen im Kernholz von Entandrophragma utile (Sipo/Utile)

Ohne Zusammenfassung