On the solar oblateness: The combined effect of a pole-equator difference in effective temperature and mechanical heating

With the help of a model atmosphere of the Sun we evaluate the pole-equator difference in flux (as measured by Dicke and Goldenberg) assuming the following type of pole-equator temperature difference (T=T _e –T _p ): (a) T 2K for > ₀ (₀ 0.05); (b) T 10K for < ₀.The small T at all optical depths given by (a) could, for example, be due to a pole-equator difference in effective temperatures. At small optical depths a difference in mechanical heating could give rise to the larger temperature difference given by (b). We compare the results of our calculations with Dicke and Goldenberg's observations.The National Center for Atmospheric Research is sponsored by the National Science Foundation.     

Explicit formula for the geoid-quasigeoid separation

The explicit formula for the geoid-to-quasigeoid correction is derived in this paper. On comparing the geoidal height and height anomaly, this correction is found to be a function of the mean value of gravity disturbance along the plumbline within the topography. To evaluate the mean gravity disturbance, the gravity field of the Earth is decomposed into components generated by masses within the geoid, topography and atmosphere. Newton’s integration is then used for the computation of topography-and atmosphere-generated components of the mean gravity, while the combined solution for the downward continuation of gravity anomalies and Stokes’ boundary-value problem is utilized in computing the component of mean gravity disturbance generated by mass irregularities within the geoid. On application of this explicit formulism a theoretical accuracy of a few millimetres can be achieved in evaluation of the geoid-to-quasigeoid correction. However, the real accuracy could be lower due to deficiencies within the numerical methods and to errors within the input data (digital terrain and density models and gravity observations).     

Response of rocks to impact loading by bars with pointed ends

SummaryResponse of Rocks to Impact Loading by Bars with Pointed Ends An experimental investigation was undertaken to study the response of three rocks — shale, limestone and diorite — to dynamic loading modelling hammer drilling. A long transmission rod subjected to pendulum impact at its distal end transmitted stress waves to six different heads whose tips consisted of 60°, 90°, and 120° cones or wedges in initial contact with the rock surface. Force and linear penetration histories monitored near the interface were found to be in good agreement with predicted values based on strain measurements at the center and distal end of the transmission bar and use of a one-dimensional theory of elastic wave propagation. The dynamic indentation measurements were also found to be in good agreement witha posteriori determination of the crater depth.Effects of multiple wave reflections and repeated impact on the contact force and rock deformation were determined as a function of the input energy. It was found that an optimum value of this energy exists for most efficient penetration for each of the heads utilized. Dynamic force-penetration curves were compared with corresponding static values obtained from an Instron testing machine. The force history resulting from the impact of a commercial pick-ax suspended in a pendulum arrangement was measured for both the conical and wedge-shaped tips of the device.

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ZusammenfassungDas Verhalten von Gesteinen unter stoartiger Belastung mittels gespitzter Stäbe Es wurde eine experimentelle Untersuchung des Verhaltens dreier Gesteine, nämlich grüner Tonschiefer, Kalkstein und Diorit, unter stoßartiger Belastung, die als Modell der Wirkung eines Bohrhammers dienen soll, durchgeführt. Ein langer Stab war vorne mit einer Spitze in Keil- oder Kegelform mit einem Öffnungswinkel von 60°, 90° oder 120° versehen, welche bei Versuchsbeginn gerade die Probe berührte. Am anderen Ende wurde der Stab von einem fallenden Pendel getroffen. Der zeitliche Verlauf der Kraft und der Eindringung, die in der Nähe der Spitze des Stabes gemessen wurde, stimmte gut mit jenen Werten überein, die auf Grund von Dehnungsmessungen in der Mitte und am Stoßpunkt mittels einer eindimensionalen Theorie der Wellenfortpflanzung errechnet wurden. Die dynamischen Tiefenmessungen des Kraters ergaben auch eine gute Übereinstimmung mit den Werten, die nach dem Experiment bestimmt wurden.Die Wirkung von mehreren Wellenreflexionen und wiederholtem Stoß auf die Kontaktkraft und die Gesteinsdeformation wurde als Funktion der Anfangsenergie bestimmt. Es zeigte sich, daß es für jede verwendete Spitzenform einen optimalen Energiebetrag gibt, bei dem die günstigste Eindringung erfolgt. Dynamische Kraft-Eindringungskurven werden verglichen mit den entsprechenden statischen Werten, die mittels einer Instron-Testapparatur gemessen wurden. Überdies wurde der Kraftverlauf an Keil- und Kegelende einer Spitzhacke, die als Pendel auf eine Steinprobe aufschlug, gemessen.

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RésuméReponses de certaines roches aux chocs exercés par des barres à extremités pointues Des expériences ont èté entreprises pour étudier la reponse de trois roches — schiste vert, calcaire, diorite — aux percussions exercées par un modèle de marteau perforateur. Un pendule ballistique heurte l'extremité libre d'une longue barre, à travers laquelle des ondes de contrainte se propagent et atteignent à l'autre extrémité une tête constitutée suivant les cas par une cône ou un dièdre d'angle 60°, 90° ou 120°, en contact avec la roche à l'instant initial. Les résultats obtenus en ce qui concerne l'évolution de la rorce et l'évolution de la pénétration lineaire sont en bon accord avec les valeurs prédites par le théorie unidimensionelle de la propagation des ondes élastiques, à partir des constrainte mesurées au centre et à l'extremité libre de la barre. Les mesures de la pénétration pendant l'experiénce sont également en bon accord avec la détermination à postériori de la profondeur des cratères.L'effet des réflexions multiples des ondes et l'effet de la répétition des impacts sur la force de contact et sur la déformation de la roche sont déterminés en fonction de l'énergie d'impact. Pour chacune des têtes utilisées on a trouvé qu'il existe une énergie optimale, c'est à dire une energie permettant d'obtenir la meilleure pénétration. Les courbes représentant la pénétration dynamique en fonction de la force sont comparées aux courbes correspondant en cas statique, obtenus par une machine d'Instron. L'évolution de la force résultant de l'impact d'une pioche ordinaire a èté mesurée pour des têtes constituées soit par des cônes soit par des dièdres.

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With 27 Figures     

Geothermal gas equilibria

Comparison of theoretical and analytical equilibrium constants based on the reactions CH₄ + 2H₂O = CO₂ + 4H₂, 2NH₃ = N₂ + 3H₂ and iron(II)-aluminium-silicate + 2H₂S = FeS₂ + H₂ + aluminium-silicate, shows that the composition of fluids discharged from geothermal areas in New Zealand (Wairakei, Kawerau, Broadlands) reflects close to complete attainment of chemical equilibrium within the system H₂O, CO₂, H₂S, NH₃, H₂, N₂ and CH₄. Under conditions prevailing in explored geothermal systems in New Zealand, the minerals graphite (elemental carbon), anhydrite, pyrrhotite, magnetite do not appear to take part in the overall equilibrium system. The three physical parameters required to evaluate geothermal gas reactions are temperature, pressure and vapor-liquid ratios within the gas equilibration zone.     

Boundary-layer diffusion modelling: The Gaussian plume approach versus the spectral solution

The equation of turbulent diffusion is solved for a vertical area source within the planetary boundary layer. The traditional Gaussian-plume approach is compared with the spectral solution of the diffusion equation used together with the barotropic boundary-layer model of Lettau and Dabberdt (1970). The results of the numerical computations are presented and the differences between the solutions are discussed.     

The role of zinc-xanthate precipitation in sphalerite flotation

Flotation of sphalerite with ethyl, propyl, butyl, amyl, and hexyl xanthate is presented as a function of pH and concentration. Surface species have been identified with infrared spectroscopy and correlated with flotation and electrophoretic results. Flotation is postulated to be controlled by the formation and adsorption of bulk precipitated zinc xanthate on the alkyl chains of chemisorbed collector species.