接地电阻测量中应注意的几个问题

参照国家有关规范和标准的要求，对接地装置、接地电阻及其测量原理进行分析和总结，指出4102型和摇表式接地电阻仪测量接地电阻时电极的布置方法对测量结果的影响。     

Evaluation ofCitrullus colocynthis, a desert plant native in Israel, as a potential source of edible oil

Citrulus colocynthis(wild gourd) is a desert plant of the Cucurbitaceae, naturally adapted to arid environments. It was known in biblical times as a source of seed oil and its fruits were used as an efficient laxative. Accessions were collected in Israel and evaluated as a potential oil seed crop adapted to arid zones. It was found that its oil composition is similar to safflower oil, with a total of 80-85% unsaturated fatty acids. A potential yield of oil of 250-400 l ha⁻¹was calculated. The best yield was obtained during the first 4 weeks of the 10-week maturation period. Yield potential should be estimated under desert conditions in order to evaluate the plant's economic future as a crop suitable for an arid environment.     

Bianchi-II Rotating World

Dynamical and kinematic properties of Bianchi-II cosmological models with rotation and expansion are investigated. Exact solutions of Einstein field equations are obtained which describe the evolution of a rotating Universe. Exact solutions of null, timelike and spacelike geodesics are constructed. Two new cosmological tests for rotating universes are discussed: cosmological lens effect and cosmological mirror effect.     

Dynamical Properties of a Sample of Ellipticals

On the basis of Jeans equations we study some dynamical properties of a sample of E galaxies considered as oblate and prolate spheroids. Although the results emphasize the anisotropy as the dominant dynamical factor both for oblate and prolate configurations, the sample contains some oblate galaxies apparently isotropic consistent with full rotational support. Comparisons of the mass-to-luminosity ratios obtained from our models with ratios derived from recent evolutionary synthesis models do not seem to leave room for nonluminous matter within the ranges (of the order of one de Vaucouleurs' radius) of the kinematical observations. Such comparisons suggest that a flatter than the classical Salpeter IMF would lead to better agreement with the dynamical results obtained within the framework of our models.     

Isoseismals of the strongest Friuli aftershocks of September 1976

Summary Isoseismal maps of the three strongest Friuli aftershocks of September 1976 were compiled using the contributions from European countries within the shaken area. The characteristic features of the macroseismic fields are discussed.     

Some remarks on the development of sedimentary basins

A simple model for the development and evolution of sedimentary basins is proposed. The first event consists of a rapid stretching of continental lithosphere, which produces thinning and passive upwelling of hot asthenosphere. This stage is associated with block faulting and subsidence. The lithosphere then thickens by heat conduction to the surface, and further slow subsidence occurs which is not associated with faulting. The slow subsidence and the heat flow depend only on the amount of stretching, which can be estimated from these quantities and from the change in thickness of the continental crust caused by the extension. The model is therefore easily tested. Preliminary investigations of the Great Basin, the Aegean, the North Sea and the Michigan Basin suggest that the model can account for the major events in their evolution.     

The variation of temperature with time and hydrocarbon maturation in sedimentary basins formed by extension

When a sedimentary basin is formed by extension both the subsidence history and the temperature gradient can be calculated. Hence the time-temperature history of any stratum can be obtained. Three types of behaviour occur. The temperature of material which never reaches depths greater than about 4 km increases at all times. The time-temperature history of material which finally sinks to greater depths reaches a maximum during the subsidence history. The time at which this maximum occurs decreases as the depth increases. At greater depths the maximum temperature occurs at the time the basin is formed. The time-temperature history is then used to calculate Lopatin's maturation index for each stratum as a function of time, and the index plotted as a function of depth and time for different amounts of extension. The maximum temperature at a given depth, and hence Lopatin's index, is almost independent of the amount of extension when the age of the basin is greater than about 150 Ma. Similar calculations taking account of sediment compaction show the same behaviour, though the maturity of the material at a given depth is increased. Because both Lopatin's index and its calibration are empirical it is important to develop new maturation indices based on individual molecular reactions whose activation energies can be determined in the laboratory.     

On the automatic interpretation of direct current resistivity soundings

A method for the automatic inversion of resistivity soundings is presented. The procedure consists of two main stages. First, application of linear filters which transforms the apparent resistivity curve into the kernel function, and vice versa. In the second stage the first and second derivatives of the kernel function are calculated and used in a second-order modified Newton-Raphson iterative fitting procedure. The model obtained is optimal in the least squares sense. The method has been tried on some field examples and produced resistivity models which show a good agreement with the geological well logs.     

The orientation of the stress axes within sinking slabs

In principle it should be possible to obtain information about the orientation of the stress axes within a sinking slab from the first motions observed at a single suitably placed seismic station. This idea is tested on the Tonga-Fiji-Kermadec Arc, using the short-period vertical seismograms from Port Moresby, and the orientations so obtained agree with those derived from fault plane solutions.