Showing papers by "University of New South Wales published in 1974"

Exact and Invariant Second-Moment Code Format

Abstract: A fundamental analysis of the meaning of second-moment reliability in multivariate problems is presented. The format described is entirely derived from one basic assumption concerning the measurement of reliability. All formulations are exact, and approximations involving the assumption of small variance are only introduced to simplify practical equations. The format is fully invariant under any change of formulation of the failure criteria consistent with the laws of algebra and mechanics.

Laser Interaction and Related Plasma Phenomena

Abstract: Report on the Thirteenth International Conference held at the Naval Postgraduate School, Monterey, California, United States of America, 13-18 April 1997.

The salt relations of marine and halophilic species of the unicellular green alga, Dunaliella. The role of glycerol as a compatible solute.

Abstract: 1. Comparisons were made of the effects of salt on the exponential growth rates of two unicellular algae,Dunaliella tertiolecta (marine) andDunaliella viridis (halophilic). 2. The algae contained glycerol in amounts which varied directly with the salt concentration of the growth media. The highest measured glycerol content ofD. tertiolecta was approximately equivalent to 1.4 molal and occurred in algae grown in 1.36 M sodium chloride. The highest glycerol content measured inD. viridis was approximately equivalent to 4.4 molal and occurred in algae grown in 4.25 M sodium chloride. Lower concentrations of free glucose, which varied inversely with extracellular salt concentration, were also detected. 3. It is inferred that Na+ is effectively excluded from the two algae. There was some evidence of a moderate uptake of K+. 4. Comparisons were made of erude preparations of the glucose-6-phosphate dehydrogenase and an NADP-specific glycerol dehydrogenase from each species and of the effects of salt and glycerol on the activities of these enzymes. It is concluded that the different salt tolerances of the two algae cannot be explained by generalized differences between their enzyme proteins. 5. Although intracellular glycerol must necessarily contribute to the osmotic status of the algae, its primary function in influencing their salt relations is considered to be that of a compatible solute, whereby glycerol maintains enzyme activity under conditions of high extracellular salt concentration and hence low (thermodynamic) water activity.

Using the Finite Element Method to Determine Temperature Distributions in Orthogonal Machining

Abstract: Temperature distributions for typical cases of orthogonal machining with a continuous chip were obtained numerically by solving the steady two-dimensional energy equation using the finite element method. The distribution of heat sources in both the primary and secondary zones was calculated from the strain-rate and flow stress distributions. Strain, strain-rate and velocity distributions were calculated from deformed grid patterns obtained from quick-stop experiments. Flow stress was considered as a function of strain, strain-rate and temperature. The chip, workpiece and tool (actual shape and size) were treated as one system and material properties such as density, specific heat and thermal conductivity were considered as functions of temperature.

Optimal Control of a Prey-Predator System*

Abstract: The purpose of this contribution is to illustrate the use of optimal control theory to obtain optimal strategies for the control of a prey-predator system. Two types of control variables are used. One control variable is the rate of release of predators or preys which are bred in laboratories. The other type of control variable is the rate of application of an insecticide. An interesting and unexpected result is that it is feasible to control a pest by means of an insecticide that destroys only the predators but leaves the pests unharmed. This is because the prey-predator system is a dynamical system. The level of the control variable and the timing of its application can be manipulated to produce desired responses from the dynamical system. Another interesting result is that the system can be controlled by releasing pests which have been bred in laboratories. These results may be useful in formulating an integrated control scheme for the management of a pest.

Oriented Nucleation in Low-Carbon Steels

Abstract: The preferred orientations in hot-rolled, cold-rolled (70 % reduction), and annealed low-carbon steels (capped and aluminium-killed grades) have been investigated. Particular attention has been paid to the factors that control texture formation during annealing.

Microbial Water Relations: Features of the Intracellular Composition of Sugar-Tolerant Yeasts

Abstract: Several factors contributed to differences in intracellular composition between sugar-tolerant (osmophilic) and nontolerant species of yeast. One such factor was the difference in accumulation of those nonelectrolytes whose uptake was not dominated by vigorous metabolism. In such cases (lactose and glycerol), the sugar-tolerant species had a much lower capacity for the solute than did the nontolerant species. Sucrose uptake was consistently different between all sugar-tolerant strains on the one hand and all nontolerant strains on the other. The difference was attributable in part to metabolism of sucrose by the nontolerant yeasts. The major difference between the two types of yeast, however, was the presence of one or more polyhydric alcohols at high concentrations within each of the sugar-tolerant strains but none of the nontolerant strains. In most cases the major polyol was arabitol. The solute concentration (and, hence, water availability) of the growth medium affected both the amount of arabitol produced by Saccharomyces rouxii and the proportion retained by the yeast after brief washing with water at 0 C. When the yeast was suspended in a buffer at 30 C, the polyol leaked out at a slow, constant, reproducible rate. The polyene antibiotic amphotericin B caused rapid release of polyol by the yeast, the rate being proportional to amphotericin concentration. Contact of the yeast with glucose (1 mM) caused an extremely rapid ejection of polyol which lasted less than 40 s. Some implications of these results are discussed, as is the role of the polyol as a compatible solute in determining the water relations of the yeast.

Transmissible plasmid coding for the degradation of benzoate and m-toluate in Pseudomonas arvilla mt-2.

Abstract: Pseudomonas arvilla mt-2 (ATCC 23073) has been shown to harbour a transmissible plasmid which codes for the degradation of benzoate and m -toluate. Plasmid-borne genetic information codes for the conversion of these compounds to catechol then the assimilation of catechol via the meta cleavage pathway.

Interaction of water waves with two closely spaced vertical obstacles

Abstract: Two-dimensional waves are incident upon a pair of vertical flat plates intersecting the free surface in a fluid of infinite depth. An asymptotic theory is developed for the resulting wave reflexion and transmission, assuming that the separation between the plates is small. The fluid motion between the plates is a uniform vertical oscillation, matched to the outer wave field by a local flow at the opening beneath the plates. It is shown that the reflexion and transmission coefficients undergo rapid changes, ranging from complete reflexion to complete transmission, in the vicinity of a critical wavenumber where the fluid column between the obstacles is resonant.

Insoluble phosphorus usage by Eucalyptus

Abstract: Eucalyptus gummifera shows a marked growth response to insoluble phosphates (AlPO4, FePO4). An hypothesis of the mechanism of phosphorus nutrition involving the interaction of root exudates, micro-organisms, aluminium ions and uptake mechanisms is presented. The hypothesis is suggested as an adaptive mechanism of E. gummifera for survival in its habitats on very impoverished soils which commonly have phosphorus content as the chief factor limiting growth. E. gummifera (Gaertn.), Hochr. is commonly found in ridge-top habitats which contain very impoverished soils. The most deficient nutrient element in these habitats is phosphorus 3. In an attempt to determine the form of phosphorus used by E. gummifera, the following experiment was carried out.

Pulmonary venous admixture during one-lung anaesthesia. The effect of inhaled oxygen tension and respiration rate.

Abstract: Previous studies during one-lung anaesthesia have demonstrated low arterial oxygen tension’,’ and the pulmonary venous admixture (shunt) was estimated from assumed values for the arterial-venous oxygen content difference,334 which however, were larger than those actually found under halothane anae~thesia .~ This resulted in an underestimate of the shunt. The present study was undertaken to measure the shunt under clinical conditions and to determine what effect varying the inhaled oxygen tension and respiration rate had on the shunt, arterial oxygen tcnsion and content.

A Study of the Drilling Process

Abstract: Drilling is a complex three dimensional cutting process yet it is possible to simulate the action of a two flute twist drill with two dimensional models provided consideration is given to the influence of the feed velocity on the cutting geometry at the drill point. Two models of chip formation and an indentation model are developed to simulate the action of the drill point. From these models equations are derived for the prediction of total torque and thrust given the cutting conditions, drill geometry, and an empirical factor which is related to the work material. Computed values of torque and thrust are shown to compare favorably with those obtained from drilling tests on an 0.45 percent C steel. The shape and magnitude of the wear zone about the chisel edge is estimated and it is shown that the observed finite thrust force as the feed rate approaches zero can be attributed to the “cutting” action of the chisel edge.

A Study of the Mechanics of Flapping Wings

Abstract: A method for the analysis of flapping-wing flight using lifting-line theory and actuator disc theory is proposed for the prediction of aerodynamic loads, propulsive efficiencies and optimum lift distributions.

Separation of the Electronic and Lattice Thermal Conductivities in Bismuth Crystals

Abstract: The thermal conductivity of pure bismuth in a very high magnetic field has a contribution from the transverse thermomagnetic effects that is not negligible compared with the lattice contribution. It is demonstrated, however, that the lattice component in the binary direction can be determined accurately from measurements of the total thermal conductivity with a high magnetic field in the bisectrix and trigonal directions. Such measurements have shown that the lattice conductivity of bismuth is strictly inversely proportional to the absolute temperature in the range 35 to 140 K, and have allowed the electronic contribution to be evaluated.

Comparison of Direct and Indirect Arterial Pressure Measurements in Hospitalised Patients

Abstract: Summary: Direct and indirect arterial pressures were compared in 30 patients by one observer in a “blind” manner. Arterial pressures were raised and/or lowered in six patients. Two cuff sizes were used (22.5× 12.5 cm and 27.5 × 11.00 cm) and skin fold thickness and arm circumference were noted. Differences as great as 25 mm Hg were noted between directly measured and indirectly measured diastolic pressure, and disappearance of Korotkov sounds was found to be more accurate than muffling as a criterion of diastolic pressure. Systolic pressure was measured much more accurately than the diastolic and was recommended as the pressure to be used as a guide to diagnosis and treatment of hypertension. No significant difference in accuracy was noted between the two cuffs. Mean difference between direct and indirect readings were systolic—3.13mm Hg diastolic muffling 17.92 mm Hg and diastolic disappearance 6.70 mm Hg. Direct pressure recording was found to be simple and painless to the patient and its more frequent use is advocated especially where there is any suspicion as to accuracy of indirect pressure.

Cleavage step deformation in brittle solids

Abstract: The nature and origin of sub-surface deformation associated with steps on cleavage surfaces of brittle solids is investigated. The geometrical configuration of step formation during cleavage is first discussed in terms of an interaction between crack segments propagating on adjacent planes. Observations of cleavage surfaces, using optical microscopy, scanning electron microscopy, and X-ray topography, are then described. It is concluded that the cleavage steps form primarily according to a mechanism in which adjacent crack segments first overlap to produce a connecting cleavage sliver, and subsequently join at one end (sometimes both ends) of the sliver to complete the separation of the cleavage halves. The slivers close in imperfect registry with the underlying parent material, thereby leaving a residual gap or dislocation network beneath the undercut steps. This mechanism is in accord with previous observations of step-associated deformation, hitherto taken as evidence of local plasticity.

Reactive Hyperemia in the Dog Heart: Effects of Temporarily Restricting Arterial Inflow and of Coronary Occlusions Lasting One and Two Cardiac Cycles

Abstract: With electromagnetic flow transducers and pneumatic cuff occluders on the circumflex branch of the left coronary artery in conscious and in anesthetized dogs, we examined the effects of both a temporary reduction in postocclusion hyperemia and one- and two-cardiac cycle occlusions of the artery on the size and the duration of the hyperemic response. After release of 8-second occlusions, flow was prevented from rising to more than 10-20% above the preocclusion value for the expected duration of the hyperemia. Peripheral coronary arterial pressure measurements established that this maneuver produced a pressure gradient. Temporary restriction of arterial inflow markedly reduced the percent repayment of the flow deficit from 618 ± 34± to 213 ± 17% (mean ± SE) and moderately prolonged the duration of the response from 95 ± 4 seconds to 129 ± 5 seconds (P < 0.0005 for both). In conscious dogs, the mean percent repayment after a one-cycle (0.7-second) occlusion was 227%. Much larger and longer-lasting responses ...

Comparative morphometrics of the acrosomes of the sperms of “externally” and “internally” fertilizing sperms of the shipworms (teredinidae, bivalvia, mollusca)

Abstract: A comparison among the sperm of eight species of teredos, four of which fertilize the eggs in the mantle cavity and four of which do not, revealed that externally fertilizing sperm have larger acrosomes and longer acrosomal rods than do internally fertilizing sperm.

Hysteresis of long-run equilibrium from realistic adjustment costs

Abstract: Publisher Summary This chapter discusses the hysteresis of long-run equilibrium from realistic adjustment costs. Much of the economic literature concerns problems of adjustment. Sometimes the adjustment process is assumed to be costless and of infinite speed. Sometimes the lag-structure plays a crucial role. Partly as an outgrowth of the lagged adjustment literature, the speed of adjustment has been assumed to be consciously chosen by firms and households in the light of the cost of adjustment. It is currently known that many traditional propositions concerning the behavior of individual firms must be either abandoned or substantially revised when costs of adjustment are allowed for. The chapter discusses the possibility of inter-industrial wage and marginal productivity differences and of the hysteresis of long-run equilibrium. Hysteresis depends on the non-differentiability at the origin of the cost-of-adjustment functions but does not depend on the special absolute value form.