A new microsecond pulse-heating system to investigate thermophysical properties of solid and liquid metals

A new discharge system for resistive self-heating has been constructed for the measurement of accurate thermophysical properties. A constant-current pulse is used to heat metals over a time interval of 50 to 100 s, reaching temperatures up to the boiling point. New techniques have been developed to obtain sound speeds in the pulse-heated sample, emissivities, and vapor pressure. A new pyrometer allows the extension of the measured temperature range down to the melting point of copper.     

The effect of appraisers in estimating metabolic rate with the Edholm scale

A study was made of the appraisers' effect on the estimation of metabolic rate with the Edholm scale and a table of the ISO 7243 heat stress standard. The appraisers, five experienced and five inexperienced persons, estimated the metabolic rate of three different work tasks from videotapes. Analysis of variance indicated significant ( [Formula: see text] ) differences in the appraisers' recordings of the activities. The appraisers were grouped according to the similarity of the estimated values they gave. The groups thus contained both experienced and inexperienced appraisers, and it was not possible to classify the appraisers into experienced and inexperienced groups according to their earlier experience. The metabolic rates according to the Edholm scale were higher than according to the ISO 7243 table. The differences in metabolic rates given by the individual observers varied from 38 to 118 W/m(2). The variations in the estimation of metabolic rates were greater when the Edholm scale was used. This variation caused considerable variation also in the predicted mean vote, PMV index. It is recommended that the appraisers be selected carefully, because it is not possible to know whether a randomly selected appraiser is an 'average' or an 'extreme' appraiser without a test. Before conducting extensive field surveys where several appraisers estimate the metabolic rates, it would be useful to arrange training in order to calibrate the levels of the Edholm scale as well as ISO method among the appraisers because training clearly unified the estimation.     

High-resolution photoelastic pressure sensor using low-birefringence fiber

The effect of birefringence induced in a single-mode fiber by a lateral force has been applied to measure the absolute value of force or pressure with high resolution. A sensor configuration with an extended detecting surface has been investigated by means of calibrated weights. The sensor is sensitive to an incremental force of 2 x 10(-3) N, independently of the length of the fiber. The maximum force applied was 10 N/m of fiber length.     

High-temperature creep and structure investigation of nearly stoichiometric Fe3Si

Single crystals of nearly stoichiometric Fe₃Si were creep-deformed at temperatureT = 450 to 850° C and applied stress=40 to 250 MPa. While the temperature dependence of the steady-state creep rate of crystals with less than 25 at% Si can be described by an exponential function exp (–H _exp/kT), the Fe-26 at% Si samples show an exponential dependence only below 500° C and above 600° C. At intermediate temperatures the dependence is weak. It is suggested that in this intermediate range two phases exist. The experimental results are consistent with the assumption that the phase boundaries do not hinder dislocation movement, and that the disocation velocity in the two phases is different.     

Effect of post-mortem temperature on beef tenderness

Beef adductor muscles were incubated for 4 h post mortem at 10°C and for 4 h and 6 h post mortem at 30°C, 37°C and 42°C. Half of the muscles were cooked just after incubation and the other half was first stored for two days at 4°C and then cooked. Meat kept for 4 h or 6 h at 42°C and for 6 h at 37°C and cooked at once had a significantly (p<0·05) lower shear force than meat kept for 4 h at 37°C, 4 h at 30°C, 6 h at 30°C or 4 h at 10°C. The respective significant differences were also found when the meat was cooked two days after incubation. Organoleptic evaluation showed that meat incubated for 6 h at 37°C or for 4 h at 42°C was not significantly more tender than other samples. However, meat kept for 6 h at 42°C was more tender (p<0·5) than the other samples. After two days of storage, meat incubated for 6 h at 37°C and for 6 h at 42° was more tender (p<0·05) than meat kept for 6 h at 30°C. It was concluded that high temperature conditioning at 37°C or higher for 6 h (4 h at 42°C) just after slaughter makes meat more tender than conventional cooling systems.     

Computergestützte Frühwarn- und Entscheidungssysteme

Zusammenfassung Die massive Bedrohung durch Nuklearwaffen, die den Supermächten die Möglichkeit zur Auslöschung allen Lebens auf der Erde geben, erfordert eine Entscheidungsfindung oftmals innerhalb weniger Minuten. Dies hat beide Seiten zum Aufbau von Frühwarn- und Entscheidungssystemen (FWES) veranlaßt, durch deren Einsatz ein atomarer Angriff noch innerhalb der Raketenflugzeit erkannt werden soll. In diesem FWES spielt die Verarbeitung und Weiterleitung von Informationen durch den Computer eine kriegsentscheidende Rolle: Die Informatik ist zu einer der wichtigsten Grundlagenwissenschaften in der Rüstungsforschung geworden. Dieser Artikel gibt eine Übersicht über die Funktionsweise computergestützter FWES und zeigt Fehlerquellen auf, die es möglich und sogar wahrscheinlich machen, daß eine Verkettung unglücklicher Umstände zu einem Nuklearkrieg aus Versehen führen kann.

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Liste der Abkürzungen ANMCC Alternate National Military Command Center - BMWES Ballistic Missile Early Warning System - CSS Communication System Segment - EMP Elektromagnetischer Puls - FWES Frühwarn- und Entscheidungssystem - ICBM Intercontinental Ballistic Missile - JCS Joint Chief of Staff - NCS NORAD Computer System - NMCC National Military Command Center - NORAD North American Aerospace Defense Command Center - PAC Pacific Command - PARCS Perimeter Acquisition Radar Attack Characterization System - SAC Strategic Air Command - SCC Space Computational Center - SLBM Submarine-launched Ballistic Missiles - WWMCCS World Wide Military Command and Control System     

Method for characterization of triacylglycerols and fat-soluble vitamins in edible oils and fats by supercritical fluid chromatography

This study demonstrates the usefulness of capillary supercritical fluid chromatography (SFC) for the characterization of triacylglycerols of edible oils and fats. Triacylglycerols were separated according to the acyl carbon number and the degree of unsaturation on a 25% cyanopropyl/25% phenyl/50% methylpolysiloxane stationary phase. Valuable information concerning the triacylglycerol composition of berry oils was obtained, despite the overlapping of certain triacylglycerol peaks. Simultaneous analysis of fat-soluble vitamins and triacylglycerols is not practical by capillary SFC with flame-ionization detection because of the low concentration of naturally-occurring fat-soluble vitamins in edible oils. Therefore, higher loading of the sample, which led to overloading of triacylglycerols, was required to get reasonable peaks for fat-soluble vitamins. The method was applied to the characterization of triacylglycerols and tocopherols in sea buckthorn pulp and seed oil, and cloudberry seed oil without any sample purification prior to SFC. In addition, the stationary phase proved useful for separating the more complex mixtures of triacylglycerols found in milk fat and in fish oil.     

Activity and Selectivity of a Nanostructured CuO/ZrO2 Catalyst in the Steam Reforming of Methanol

Steam reforming of methanol for production of hydrogen can be carried out over copper based catalyst. In the work presented here, the catalytic properties of a CuO/ZrO₂ catalyst (8.5wt%) synthesised by a templating technique were investigated with respect to activity, long term stability, CO formation, and response to oxygen addition to the feed. The results were obtained using a fixed bed reactor and compared to a commercial methanol synthesis catalyst CuO/ZnO/Al₂O₃. It is shown that, depending on the time on stream, the temporary addition of oxygen to the feed has a beneficial effect on the activity of the CuO/ZrO₂ catalyst. After activation, the CuO/ZrO₂ catalyst is found to be more active (per copper mass) than the CuO/ZnO/Al₂O₃ system, more stable during time on stream (measured up to 250h), and to produce less CO. Structural characterisation by means of X-ray powder diffraction (XRD) and X-ray absorption spectroscopy (XAS) reveals that the catalyst (as prepared) consists of crystalline, tetragonal zirconia with small domain sizes (about 60Å) and small/disordered crystallites of CuO.     

Electrolytical fission at mercury cathodes of an NO single bond in ethers derived from 1-hydroxybenzo(d)-1,2,3-triazoles

The single NO bond in various ethers derived from 1-hydroxybenzo(d)-1,2,3-triazoles is reduced at mercury cathodes in a 2-electron process giving rise to the non-substituted benzotriazole and a corresponding primary alcohol. Controlled-potential electrolysis actually resulted in isolating the products of the above type eg benzotriazole and 2-piperidinoethanol. Cathodic reduction of non-substituted benzotriazole in acid media proceeds evidently via a chemical reaction between benzotriazole and hydrogen obtained by the catalytic reduction of hydrogen ions at the mercury electrode.