Evaluating along‐strike variation using thin‐bedded facies analysis,Upper Cretaceous Ferron Notom Delta,Utah

Thin‐bedded delta‐front and prodelta facies of the Upper Cretaceous Ferron Notom Delta Complex near Hanksville in southern Utah, USA, show significant along‐strike facies variability. Primary initiation processes that form these thin beds include surge‐type turbidity currents, hyperpycnal flows and storm surges. The relative proportion of sedimentary structures generated by each of these depositional processes/events has been calculated from a series of measured sedimentological sections within a single parasequence (PS6–1) which is exposed continuously along depositional strike. For each measured section, sedimentological data including grain size, lithology, bedding thickness, sedimentary structures and ichnological suites have been documented. Parasequence 6–1 shows a strong along‐strike variation with a wave‐dominated environment in the north, passing abruptly into a fluvial‐dominated area, then to an environment with varying degrees of fluvial and wave influence southward, and back to a wave‐dominated environment further to the south‐east. The lateral facies variations integrated with palaeocurrent data indicate that parasequence 6–1 is deposited as a storm‐dominated symmetrical delta with a large river‐dominated bayhead system linked to an updip fluvial feeder valley. This article indicates that it is practical to quantify the relative importance of depositional processes and determine the along‐strike variation within an ancient delta system using thin‐bedded facies analysis. The wide range of vertical stratification and grading sequences present in these event beds also allows construction of conceptual models of deposition from turbidity currents (i.e. surge‐type turbidity currents and hyperpycnal flows) and storm surges, and shows that there are significant interactions and linkages of these often paired processes.     

阿勒泰市强降水衍生泥石流灾害分析

调查分析阿勒泰市区泥石流灾情、引发的气象因素以及有利的环流形势.结果表明:阿勒泰市泥石流灾害以市区东北部发生频率高,为重灾区,阿勒泰市泥石流主要发生在6-8月的强雷雨时段;中小尺度强雷雨是引发阿勒泰市泥石流直接的动力因素,降水超过15 mm并伴有雷暴可作为阿勒泰市泥石流气象预警指标;阿勒泰市夏季中小尺度系统引发的短时强降水有两种天气尺度环流背景.     

Do bilateral trade relationships influence the distribution of CDM projects?

The use of the Clean Development Mechanism (CDM) is increasingly widespread in developing countries. However, CDM projects are still far from being an effective development activity due to the uneven distribution of these projects in a few relatively well-off economies. One potential cause of this imbalance is analysed in terms of the trade relationships between developed and developing countries. By applying a gravity model to a panel dataset, well-established export flows from developed economies towards developing countries are shown to explain why a large proportion of CDM projects are unevenly geographically distributed. This kind of lock-in effect regarding the CDM between developed and developing countries could be avoided by both enhancing the institutional framework in developing countries that host CDM projects and reinforcing compulsory rules for CDM destinations in the least-developed economies.     

空间碎片观测精度分析

文章分别用内符合精度和外符合精度两种精度指标对云南天文台SBG望远镜的观测数据进行判定，确定了其观测精度。得到高轨空间碎片的观测精度约为2″，和低轨空间碎片的观测精度约为7″，并对观测误差的来源作了一些初步的分析。     

Analysis of the Space Debris Impacts Risk on the International Space Station

Öpik's analytical expressions relate in a simple way the semimajor axis, eccentricity and inclination of the projectile orbit to the magnitude and direction of the relative velocity vector at impact on a given target on circular orbit. These interesting quantities, along with the impact probability of any given projectile, can be all represented on a suitable projection giving a comprehensive picture of the impact risk on the selected target. By means of this theory a complete analysis of the impact risk on the International Space Station (ISS) is performed. It is found that the large majority of the debris population is on orbits such that a correlation exists between their impact velocity on the ISS and the angle between the velocity vector of the impactor and that of the ISS. The impactor population also is separated in terms of nature of the projectiles, with most of the low-medium velocity ones being particles related to solid rocket motor slag condensates. On the other hand, the highest velocity projectiles are composed mainly by fragments of past in-orbit explosions.The flux of projectiles on the ISS has been calculated for the planned operative lifetime of the Station, by assuming a realistic scenario of the future debris environment evolution and the actual planned altitude profile for the ISS mission. There is a factor 2-3 variation of the flux due to the changing ISS altitude. The most dangerous part of the mission appears to be the central one, when the ISS will orbit at about 450 km above the Earth.     

Heating rate profiles in galaxy clusters

In recent years, evidence has accumulated suggesting that the gas in galaxy clusters is heated by non-gravitational processes. Here, we calculate the heating rates required to maintain a physically motivated mass flow rate, in a sample of seven galaxy clusters. We employ the spectroscopic mass deposition rates as an observational input along with temperature and density data for each cluster. On energetic grounds, we find that thermal conduction could provide the necessary heating for A2199, Perseus, A1795 and A478. However, the suppression factor of the classical Spitzer value is a different function of radius for each cluster. Based on the observations of plasma bubbles, we also calculate the duty cycles for each active galactic nucleus (AGN), in the absence of thermal conduction, which can provide the required energy input. With the exception of Hydra-A, it appears that each of the other AGNs in our sample requires duty cycles of roughly 10⁶–10⁷ yr to provide their steady-state heating requirements. If these duty cycles are unrealistic, this may imply that many galaxy clusters must be heated by very powerful Hydra-A type events interspersed between more frequent smaller scale outbursts. The suppression factors for the thermal conductivity required for combined heating by AGN and thermal conduction are generally acceptable. However, these suppression factors still require 'fine-tuning' of the thermal conductivity as a function of radius. As a consequence of this work, we present the AGN duty cycle as a cooling flow diagnostic.     

On viscosity, conduction and sound waves in the intracluster medium

Recent X-ray and optical observations of the Perseus cluster indicate that a combination of weak shocks at small radii  (≳20  kpc)  and viscous and conductive dissipation of sound waves at larger radii is responsible for heating the intracluster medium and can balance radiative cooling of cluster cores. We discuss this mechanism more generally and show how the specific heating and cooling rates vary with temperature and radius. It appears that this heating mechanism is most effective above  10⁷  K  , which allows for radiative cooling to proceed within normal galaxy formation but stifles the growth of very massive galaxies. The scaling of the wavelength of sound waves with cluster temperature and feedback in the system are investigated.     

Dynamics of Mass-Loaded Wind

The structure of a steady state, spherically symmetric flow with a distributed mass source and sink is examined in this paper: the source corresponds to the arrival of mass from vaporizing clouds and the sink, to the possible condensation of gas owing to a thermal instability. Depending on the efficiency of the mass source, three types of flow can exist: (a) supersonic or subsonic flows everywhere, and flows with (b) one or (c) two critical (sonic) points. Condensation of the gas shifts the critical point (if it exists) outward. External gravitation does not change the flow structure qualitatively, unlike in the case of flows without mass sources and sinks.__________Translated from Astrofizika, Vol. 48, No. 2, pp. 315–329 (May 2005).     

Early Holocene High Magnitude Debris Flow Events and Environmental Change as Illustrated by the Moxi Platform, Hengduan Mountains, SW China

Introduction Landscape evolution in glaciated high mountains environment in southwestern China is undergoing the coupled processes of monsoon- induced denudation and active tectonic. The debris fan development, in particular sediment transfer, is most int…