Metabolic-heat relation for aerobic yeast respiration and fermentation

A specially developed temperature control system on a laboratory scale fermenter enabled continuous measurement of the rate of heat production during undisturbed growth of microbial cultures. Apart from being correlated with oxygen uptake rate, the heat of fermentation was established as an additional indicator of metabolic activity. The ‘aerobic respiration’ energetic activity of Candida utilis, Candida lipolytica and Saccharomyces cerevisiae on different carbon substrates was investigated with cultures of the latter species being also studied under the ‘aerobic fermentation’ conditions induced by glucose catabolite repression.     

Microsomal and photochemical oxidation of aflatoxin B1

The UV irradiation (lambda = 362 nm) of aflatoxin B1 (AfB1) dissolved in water resulted in the formation of an oxidized product. The process was not inhibited by ionol, a routine inhibitor of the radical processes. The oxidized product was not found in the system where AfB1 was metabolized by the 3-methylcholanthrene-activated rat liver microsomes. It is suggested that the product is identical with 2,3-dihydrodiol of AfB1.     

New long-chain hydroxy acids fromGrevillea decora

In addition to the ω-5 olefinic acids found in otherGrevillea species, about 10% of the acyl groups ofG. decora seed oil contain a hydroxy group and an ω-5 double bond. The chainlengths of these acids are from C₂₂ to C₃₀, with the largest concentration at the C₂₆ and C₂₈ chainlengths. The hydroxy group is located on odd carbons from carbon-5 through carbon-13. These acids previously were unknown in nature. The most abundant of these are 7-hydroxy-cis-17-docosenoic, 7-hydroxy-cis-19-tetracosenoic, 9-hydroxy-cis-19-tetracosenoic, 9-hydroxy-cis-21-hexacosenoic, 11-hydroxy-cis-21-hexacosenoic, and 13-hydroxy-cis-23-octacosenoic acids. The oil also contains the largest known concentration of the unoxygenated C₂₆ and C₂₈ ω-5 monoenes.     

The concept of an endurance limit for adhesive joints

The effect of cyclic stressing on the strength of single lap adhesive joints has been studied and a considerable reduction in strength observed when the maximum stress exceeds about 40% of the ultimate tensile strength, but whether or not a true endurance limit exists is not proven. Fallacies are shown in some of the techniques which have been proposed for studying the fatigue behaviour of adhesive joints.     

Nonlinear circuit analysis using the method of harmonic balance—A review of the art. Part I. Introductory concepts

The harmonic balance method is a technique for the numerical solution of nonlinear analog circuits operating in a periodic, or quasi-periodic, steady-state regime. The method can be used to efficiently derive the continuous-wave response of numerous nonlinear microwave components including amplifiers, mixers, and oscillators. Its efficiency derives from imposing a predetermined steady-state form for the circuit response onto the nonlinear equations representing the network, and solving for the set of unknown coefficients in the response equation. Its attractiveness for nonlinear microwave applications results from its speed and ability to simply represent the dispersive, distributed elements that are common at high frequencies. The last decade has seen the development and application of harmonic balance techniques to model analog circuits, particularly microwave circuits. The first part of this paper reviews the fundamental achievements made during this time. The second part covers the extension of the method to quasi-periodic regimes, optimization analysis, and practical application. A critical assessment of the various types of harmonic balance techniques is given. The different sampling and Fourier transform methods are compared, and numerical speed and precision results are given enabling a quantitative analysis of the merits of the major variants of the harmonic balance technique. Examples of designs which have been modeled using the harmonic balance technique and built both in hybrid and MMIC form are presented.     

Neural network payload estimation for adaptive robot control

A concept is proposed for utilizing artificial neural networks to enhance the high-speed tracking accuracy of robotic manipulators. Tracking accuracy is a function of the controller's ability to compensate for disturbances produced by dynamical interactions between the links. A model-based control algorithm uses a nominal model of those dynamical interactions to reduce the disturbances. The problem is how to provide accurate dynamics information to the controller in the presence of payload uncertainty and modeling error. Neural network payload estimation uses a series of artificial neural networks to recognize the payload variation associated with a degradation in tracking performance. The network outputs are combined with a knowledge of nominal dynamics to produce a computationally efficient direct form of adaptive control. The concept is validated through experimentation and analysis on the first three links of a PUMA-560 manipulator. A multilayer perceptron architecture with two hidden layers is used. Integration of the principles of neural network pattern recognition and model-based control produces a tracking algorithm with enhanced robustness to incomplete dynamic information. Tracking efficacy and applicability to robust control algorithms are discussed.     

First experiences with the modelling and simulation package MIRACLES applied to a picture archiving and communication system (PACS) in a clinical environment

Since the construction of picture archiving and communication systems (PACS) appears to be extremely difficult, computer modelling and simulation are used as decision support tools. The package MIRACLES (Medical Image Representation, Archiving and Communication Learned from Extensive Simulation) has been developed at BAZIS in order to support the construction of simulation models of image information systems. This article discusses the application of MIRACLES to a prototypical PACS as being installed in a clinical environment. Attention is focussed to the required system analysis and difficulties which arose during the construction of the simulation model. The emphasis is on the presentation of the results of the simulation study, which show that simulation can be fruitfully used to predict, to analyse and to assist in solving performance problems. The simulation study confirmed assumptions and suppositions concerning both the system performance itself and strategies to improve the performance. The study also resulted in a number of concrete recommendations which might be useful for the set-up of the prototypical PACS.     

Simulation and optimization of tool-life in manufacturing centers

This paper presents the development of an optimization and a computer-simulation model to evaluate the process plans of a manufacturing center by analyzing the effect of tool failure on system performance. The GPSS/PC simulation program that is used in this study has been built with variables, functions and matrices so that many experiments could be conducted with the model. Sensitivity analysis is presented and the developed model has proven to be useful in determining optimum sequencing of parts for various operating policies.     

Neutron and capture γ-ray accumulation factors in engineering calculations of reactor shielding

Translated from Atomnaya Énergiya, Vol. 66, No. 5, pp. 321–324, May, 1989.     

Space asymptotic method for the study of neutron propagation

Space asymptotic theory is shown to be a suitable model for the study of pulsed experiments in neutron multiplying systems. After a short revisitation of the basic aspects of space asymptotic theory applied on the Laplace transformed one-group transport equation, the full solution is derived. It is shown how results are exact in representing localized pulse propagation in the first portion of the transient, until the boundary is reached by the neutron signal, since it propagates with a finite velocity. Approximate models are then derived starting from the exact formulation and the B_N method is used to account for anisotropy effects. Numerical results are presented for one-dimensional systems, discussing the physical phenomena and noting the distortions introduced by approximate models, which may then turn out to be inadequate for the simulation of realistic pulsed experiments situations.