Rank-size distributions of Chinese cities: Macro and micro patterns

A large number of studies have been conducted to find a better fit for city rank-size distributions in different countries. Many theoretical curves have been proposed, but no consensus has been reached. This study argues for the importance of examining city rank-size distribution across different city size scales. In addition to focusing on macro patterns, this study examines the micro patterns of city rank-size distributions in China. A moving window method is developed to detect rank-size distributions of cities in different sizes incrementally. The results show that micro patterns of the actual city rank-size distributions in China are much more complex than those suggested by the three theoretical distributions examined(Pareto, quadratic, and q-exponential distributions). City size distributions present persistent discontinuities. Large cities are more evenly distributed than small cities and than that predicted by Zipf′s law. In addition, the trend is becoming more pronounced over time. Medium-sized cities became evenly distributed first and then unevenly distributed thereafter. The rank-size distributions of small cities are relatively consistent. While the three theoretical distributions examined in this study all have the ability to detect the overall dynamics of city rank-size distributions, the actual macro distribution may be composed of a combination of the three theoretical distributions.     

The Nature and Age of Plagioclasites in the Ultrabasic Rai-Iz Massif (Polar Urals)

Corundum-containing and corundum-free plagioclasites localized in chromite-bearing ultramafites of the Rai-Iz Massif were explored for the composition and age. The composition of rock-forming minerals was studied, and the geochemical characteristics of the rocks were ascertained. The isotope age of plagioclasites determined by zircons using the U–Pb mode with a SHRIMP II device was equal to 398 ± 3 Ma. The age found conformed to the boundary on most of the Rai-Iz Massif took place against the background of a starting powerful collision, which caused the formation of the chromium mineralization of a high-chromic type, as well as the separation of a series of essentially plagioclase rocks of ruby mineralization at the discharge zones of the vein series.     

Experimental study of the mechanical properties of expansive soil with added nanomaterials

The main purpose of this paper is to describe ways to improve the microstructure of expansive soil by adding nanomaterials. Mechanical tests were done to explore the changes in shear strength and compression index of expansive soil that was modified by adding different amounts of two kinds of nanomaterials (nano-alumina and nano-silica). The test results show that adding 1.2% nano-alumina and about 2% nano-silica to expansive soil provides the optimal compression index. The test results show that adding 1.2% nano-alumina and about 1.5% nano-silica to expansive soil provides the optimal unconfined compression stress. Scanning electron microscopy of the microstructure of expansive soil modified by nanomaterials provided a deeper understanding of the effects of nanomaterials on improving expansive soil.     

Depositional Environments and Paleogeographic Evolution during the Formation of Upper Paleozoic Terrigenous Rocks in Taimyr

Lithology and Mineral Resources - Upper Paleozoic sections in Taimyr comprise genetic rock complexes of different zones: deep-water shelf; offshore transition zone; shoals, deltas, and beaches of...     

Tectonic Position of the South Anyui Suture

Geotectonics - The South Anyui Fold System was formed at the end of the Early Cretaceous at the site of a closed oceanic basin as a result of the collision of the Chukotka microcontinent with the...     

Confusion Noise Sources in the Infrared Wavelength Range

Astronomy Reports - Within the framework of the model of the extragalactic background created earlier by the authors, the factors influencing the statistical properties of the confusion noise have...     

Resistance of Enzymes to Ionizing Radiation under Model Conditions of the Martian Regolith

Solar System Research - Ionizing radiation is one of the main factors that destroy biomolecules in extraterrestrial conditions. The effects of radiation depend on the conditions of the exposure...     

Spectroscopic Redshift Measurements for Galaxy Clusters from the Lockman Hole Survey with the eROSITA Telescope Onboard the SRG Observatory

Astronomy Letters - We present the first results of our program of optical observations for galaxy clusters from the Lockman Hole X-ray survey with the eROSITA telescope onboard the SRG space...     

Implementation of the Concept for Creating a Spacecraft Double-Launch System as a Part of the Upper Stages of the Fregat Family

Solar System Research - Abstract—Results of the implementation of a single concept for the development of the double launch system (SDZ) are presented, in particular the SDZ-La5 for the...