VITAMIN C AND β-CAROTENE IN FRESH AND FROZEN GREEN BEANS AND BROCCOLI IN A SIMULATED SYSTEM

The reduced ascorbic acid and β-carotene contents of “retail market-fresh” (RMF) and “fresh-frozen” (FF) green beans and broccoli in a simulated handling system were determined. Changes in ascorbic acid content in the two vegetables during a retail market period and frozen storage followed different patterns. In green beans, ascorbic acid content decreased during refrigerated storage for up to 7 days, but in broccoli there was a significant increase. Blanching resulted in a loss of approximately 40% of the ascorbic acid in broccoli. Ascorbic acid content of FF green beans stored at-20C for 16 weeks was approximately twice that in RMF green beans, but in FF broccoli stored under the same conditions it was only about half that of RMF broccoli. β-carotene content of green beans and broccoli did not change during either the retail market simulation of frozen storage and did not differ from that of fresh.     

4He films on graphite studied by neutron scattering

The properties of ⁴He films adsorbed on graphite have been studied by neutron scattering. In particular excitations of the commensurate phase of the monolayer are discussed. The first two adsorbed layers are solid and the next ones stay liquid. At the boundaries of the superfluid film excitations could be studied. Also the phonons, maxon and rotons of the film are investigated. An explanation of the lower density of the very thin films compared to bulk ⁴He is given.Presented by H. J. Lauter.     

An investigation into the performance and cost effectiveness of thermosyphon solar water heaters

In this paper, the TRNSYS Simulation Program is used to investigate the monthly and annual solar fraction of a Thermosyphon Solar Water Heater and to evaluate its economic viability in terms of its life cycle savings over a conventional water heating system. The results of the simulation indicate that the yearly solar contribution of the system ranges from 63% for a high hot water consumption profile to 89% for a low consumption pattern. The payback period of the system is as low as 3 years when compared to electric water heating systems. As long as the competitor is diesel oil, the payback period increases to 7–9 years, depending on the hot water consumption profile used.     

A theoretical and photoelastic contact stress analysis relevant to orthopaedic knee prostheses

This study is based on a theoretical and photoelastic static contact stress analysis, relevant to the design of the plastic tibial plateau in an orthopaedic knee prosthesis. It involves the review of existing theoretical analyses concerned with the contact mechanics of layered elastic systems and, where possible, the validation of any relevant findings using two dimensional photoelasticity. Significant findings include the identification of a general minimum recommendable design thickness for the plastic tibial plateau, the endorsement of using the Hertzian contact theory to predict contact stress levels in the tibial plateau of certain knee implants and the slight improvement in contact conditions in the plastic when the plateau is perfectly bonded to its supporting metal tray.     

The symmetric ellipsoid failure surface for the transversely isotropic body

Summary A realistic criterion in the 3D-principal stress space for describing failure of transversely isotropic bodies taking also into account the strength differential effect was shown to be the elliptic paraboloid failure surface (EPFS) [5]. The criterion, however, stipulates that in the compression-compression-compression octant these materials may sustain very high loadings. In order to remedy this ambiguous definition of failure in this zone for the compression strong materials or in the domain of the tension-tension octant for the tension strog materials an improved version of the EPFS was introduced in this paper. Based on the same principles as the EPFS a symmetric ellipsoid failure surface is defined whose symmetry axis is parallel to the hydrostatic axis, which is also passing through the three pairs of failure strengths in tension and compression along each of the principal stress axes.Since the symmetric ellipsoid failure criterion is a versatile one, based on the same hypotheses derived from assertions and long experrimental evidence as the EPFS, thus succeding to interrelate failure with the basic concepts and principles of mechanics, it constitutes a powerful and reliable general type of criterion. It was shown that extensive experimental evidence corroborates the results derived from this criterion along the basic intersections of this failure surface.     

Computation of laminar flow in mixed turbulent convection and its influence on heat transfer

Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 62, No. 3, pp. 366–372, March, 1992.     

Measurement of synchronous machine rotor angle from analysis ofzero sequence harmonic components of machine terminal voltage

Generator rotor angle measurement is useful in identification of electric machine parameters in the d and q axes and as an indicator of stability of the operating condition. Rotor angle measurements with the appropriate bandwidth are also very useful in observation of rotor torsional oscillations both for monitoring and protection against undamped torsional modes, and for use in control schemes designed to damp torsional oscillations. A method of measurement of synchronous machine rotor angle from an analysis of the phase angle of zero sequence harmonic components of terminal voltage is presented     

Ultralow-Dielectric-Constant foams by crystallisation from supercritical solution: Application to advanced electronic packaging

Accurate moulding of polymer foams of density 0.02–0.3 g cm^?3 has been achieved by crystallising polyethylene and ethylene/methlacrylate copolymers from dry supercritical solutions. Adherent thick films can be sealed to electronic substrates and are proposed as insulating layers for interconnections on multichip modules and other high-speed electronic devices. The dielectric constant achieved for films of several-mil thickness is between 1.05 and 1.3 and can be tailored along with the physical properties of the film by adjusting the density and composition of the copolymer. Planarisation or complex patterning is possible by detailing the mould.     

All-optical photonic switches using integrated inverted asymmetricFabry-Perot modulators and heterojunction phototransistors

InGaAs/GaAs(100) multiple-quantum-well-based inverted cavity asymmetric Fabry-Perot modulators are vertically integrated with GaAs/AlGaAs heterojunction phototransistors to yield all-optical photonic switches. The photonic switches using `normally on' modulator pixels exhibit an output on-off ratio of 12:1 with internal optical gain of 4 dB. The photonic switches using `normally off' modulator pixels yield similar contrast and gain, but exhibit intrinsic bistable behavior. The inverted cavity modulators employed permit utilizing the transparency of the GaAs substrate at the operating wavelength and offer advantages for fabricating large arrays for optical signal processing