A comparative study of the segmentation of weighted aggregation and multiresolution segmentation

Multiresolution segmentation (MRS) algorithm has been widely used to handle very-high-resolution (VHR) remote sensing images in the past decades. Unfortunately, segmentation quality is limited by the dependency of parameter selection on users’ experience and diverse images. Contrarily, the segmentation by weighted aggregation (SWA) can partly overcome the above limitations and produce an optimal segmentation for maximizing the homogeneity within segments and the heterogeneity across segments. However, SWA is solely tested and justified with digital photos in computer vision field instead of VHR images. This study aims at evaluating SWA performance on VHR imagery. First, multiscale spectral, shape, and texture features are defined to measure homogeneity of image objects for segmentation. Second, SWA is implemented to handle QuickBird, unmanned aerial vehicle (UAV), and GF-1 VHR images and further compared with MRS in eCognition software to demonstrate the applicability of SWA to diverse images in building, vegetation and water, forest stands, farmland, and mountain areas. Third, the results are fully evaluated with quantitative measurements on segmented objects and classification-based accuracy assessment on geographic information system vector data. The results indicate that SWA can produce higher quality segmentations, need fewer parameters and manual interventions, create fewer segmentation levels, incorporate more features, and obtain larger classification accuracy than MRS.     

水滑石类化合物的研究进展及其在PP中的应用进展

水滑石类化合物是一种重要的无机材料,因其特殊的晶体化学性质,有良好的热稳定性、阻燃性和离子交换性,广泛应用于化工、材料、环保和医药等领域。本文综述了水滑石类化合物的结构、性质、制备方法及其优缺点,水滑石在PP中的应用进展,以及水滑石作为PP阻燃剂的优异性能,并指出了今后的发展方向。     

中国气象局S2S数据归档中心设计及关键技术

中国气象局S2S（Sub-seasonal to Seasonal）数据归档中心建设是中国气象局承担世界气象组织（WMO）的世界天气研究计划（WWRP）和世界气候研究计划（WCRP）任务,由国家气象信息中心负责设计和实现。该文介绍了S2S数据归档中心建设中涉及的数据交换、数据检查及处理、数据归档存储及数据服务门户全流程系统设计和实现。针对各业务中心生产的S2S数据配置差异较大造成数据交换、同步较难这一问题,采用基于FTP（file transfer protocol）的数据推送和基于ECMWF（European Center for Medium-range Weather Forecasts）WebAPI主动数据下载相结合的方式,说明数据交换、同步方法和策略。由于S2S数据量巨大难以高效管理服务,已设计统一的数据组织形式和存储规则,实现根据数据检索条件解析获取数据存储位置,提供便捷的数据检索下载服务。自2015年11月15日中国气象局S2S数据门户系统对外开放,目前数据门户系统已有超过18个国家的300个用户注册并下载数据。     

Limits of warm and cold bioclimatic stress in different climatic regions

Summary Limits of warm and cold stress in different climatic regions are determined by means of temperature, wind speed and humidity for the period 1976–1985. These values are measured at 2 PM local time during July for warm stress and at 7 AM local time during January for cold stress. Hvar (20 m ASL) is used to represent maritime climate, Zavian on the top of Mount Velebit (1594 m ASL) and Skrad (668 m ASL) in Gorski Kotar are representative of mountainous climate, and Zagreb (128 m ASL) is representative of continental low-land climate. Values of a biometeorological Temperature-Wind Speed-Humidity (TWH)-index higher than the 98% value of the theoretical distribution fitted to empirical data represent above normal extreme conditions at a given location, and TWH values less than 2% value of the theoretical distribution represent below normal extreme conditions. For similar temperatures, it will be extremely above normal at the top of Mount Velebit (Zavian) whilst normal on the coast (Hvar), and similarly, it will be extremely below normal in Hvar but normal at Zavian.With 4 Figures     

An analysis of active close binaries (CB) based on photometric measurements

For the purpose of analysing light curves of active CB with an accretion disc being at the evolutional phase of an intensive matter exchange between the components a model for light-curve synthesis has been realized where the attention is given to systems like W Ser not sufficiently examined yet with regard that in them the accretion disc is formed around an ordinary star. In the paper one uses the elements presented in the first paper of this series. The model can successfully describe the essential characteristics of the observed light curves due to existence of an accretion disc and a hot spot, as well as those originated in the temperature distribution along the disc radius. The system components are considered in the framework of the nonsynchronous Roche model and the accretion disc of a constant thickness lies in the orbital plane around the star capturing the matter of the neighbouring component.The primary surrounded by the disc is situated relatively well within the Roche oval and its rotation can be significantly nonsynchronous. Near the Lagrange equilibrium pointL ₁ flows from the secondary (which fills the Roche limit) the gas stream nourishing the disc. In the zone where the stream touches the lateral side of the disc a hot spot is formed.The proposed model enables estimating of the basic orbital and physical parameters of active type W Ser CB (Djuraevi, 1991) on the basis of photometric measurements by applying the inverse-problem method.     

Orbital eccentricity study for the spherical component of our galaxy

An analysis of the data concerning high-velocity stars from Eggen's catalogue aimed at a determination of the approximate slope of the mass function for the spherical component of our Galaxy, and at estimating the local circular velocity, as well as the local rotation velocity, as by-products, has been performed. Our conclusions are that:

1. A linear dependence of the mass on the radius is very likely;
2. the value of the limiting radius is most likely equal to (40±10) kpc;
3. the two local velocities are approximately equal to each other, being both equal to (230±30) km s^?1;
4. the local escape velocity appears to be most likely equal to (520±30) km s^?1;
5. the total mass of a corona, obtained in this way, is (5±1)×10¹¹ M _⊙.

     

The chronostratigraphy of the latest Middle Pleistocene aeolian and alluvial activity on the Island of Hvar,eastern Adriatic,Croatia

Pleistocene aeolian sands and alluvial deposits can frequently be traced along the Mediterranean coast. Such deposits also exist along the eastern Adriatic coast and the nearby islands. Four stratigraphical sections of these deposits were studied on the Island of Hvar with the purpose of establishing a chronological framework of the aeolian–alluvial depositional system, using luminescence dating and magnetic susceptibility stratigraphy. Luminescence dating was applied on coarse‐grained feldspar and quartz grains separated from the sands. Both quartz optically stimulated luminescence (OSL) and feldspar post‐IR infrared stimulated luminescence (pIRIR) age estimates are in good agreement, with values ranging between 167±24 to 120±12 ka (OSL) and 179±18 to 131±18 ka (pIRIR measured at 290 °C) after a fading correction for the pIRIR signal. The results can be clearly correlated to around the end of oxygen isotope stage (OIS) 6 and the beginning of OSI 5, indicating that the aeolian accumulation of sands was a result of the Penultimate Glacial and climate fluctuations at the beginning of the Last Interglacial. Variations in magnetic susceptibility (MS) data can be interpreted alongside these dating results; several stronger peaks detected at the very end of the Penultimate Glacial and the initial stage of the Last Interglacial cycle most probably indicates more intensive pedogenesis resulting from a more favourable climate, probably because of climate changes. Breccias related to major bounding surfaces in association with evidence of soil formation and bioturbation could be the result of more favourable climate conditions and changes during the transition from OIS 6 to OIS 5 (Penultimate Glacial–Last Interglacial). These results are in agreement with similar data from the wider Mediterranean area.