辐射交联聚乙烯热膨胀内衬管研究

研究了用高能电子束辐射交联线性低密度聚乙烯/高密度聚乙烯/低密度聚乙烯/乙烯-醋酸乙烯酯共聚物(LLDPE/HDPE/LDPE/EVA)管材的性能,包括辐照剂量与凝胶含量、力学性能以及熔融特性的关系等。结果表明,辐照剂量为96 kGy、凝胶率为56%时,拉伸强度最高;随着辐照剂量的增大熔点呈下降趋势。另外,研究结果还表明,定径拉伸法制造的热膨胀管牺牲更小的轴向变化就可以达到与自由拉伸法制造的热膨胀管相同的径向变化。     

Satellite‐derived estimates of evapotranspiration in the arid and semi –arid region of Mongolia

Estimating evapotranspiration (ET) is of the highest importance for understanding and eventually intervening in the water cycle of natural systems. ET is one of the major factors influencing climate change at local, regional and global levels. In this study, a surface energy balance method, which combines meteorological observations with spectral data derived from remote sensing measurements, was used to estimate the ET. The Surface Energy Balance Algorithm for Land (SEBAL) has been applied to Landsat+ETM and NOAA‐AVHRR sensors for the estimation of ET in Mongolia, a large arid and semi‐arid region with homogeneous surface conditions, on 10 August 1999. Actual ET was computed during satellite overpass and integrated for 24‐h on pixel‐by‐pixel basis for daily ET distribution. As a result, a daily ET map over the arid and semi‐arid region of Mongolia was analysed some observation data, such as radiations and surface temperature, was compared with estimated data.     

Physicochemical and catalytic properties of iron- and indium-containing zeolites

The influence of the preparation procedure of Fe- and In-containing zeolites on their physicochemical and catalytic properties in methanol conversion to hydrocarbons and the upgrading of the straight-run gasoline fraction of crude oil has been studied. The introduction of In and Fe into a zeolite increases the on-stream time of the catalysts in methanol conversion and increases their selectivity for the formation of alkenes and isoalkanes. Zeolites containing iron and indium nanopowders are the most effective catalysts for the manufacturing of high-octane gasolines from straight-run gasoline.     

东鞍山难选铁矿捕收剂的合成及工业应用

基于东鞍山入选铁矿石铁品位降低和组成变化,KS-Ⅰ捕收剂面临很大的挑战,难以满足炼铁工业的要求。设计和合成了一种KS-Ⅲ捕收剂,并应用于东鞍山烧结厂的浮选试验。与KS-Ⅰ浮选药剂相比,1号矿样铁精矿品位提高0.43个百分点、尾矿铁品位降低0.56个百分点以上、捕收剂的单位耗量减少6.89个百分点,铁的回收率提高0.31个百分点。     

Spatio-temporal Dynamics of Vegetation Phenology in the Mongolian Plateau during 1982~2011

Based on the third generation GIMMS NDVI time\|series datasets during 1982~2011,we extracted the start of growing season (SOS),end of growing season (EOS) and length of growing season (LOS) in the Mongolian Plateau using cumulative NDVI based logistic regression curves,change rate of curvature in NDVI logistic regression curves and change rate method of NDVI and further analyzed the spatio\|temporal changes of phenology.The results showed that the cumulative NDVI based logistic regression curves and change rate method of NDVI performed better predictions in SOS and EOS modeling,and the mean value of these two methods improved the extraction accuracy of phenology in the Mongolian Plateau.SOS in the Mongolian Plateau mostly started from the middle of April to the end of May and ended from the end of the September to the middle of the October.Most LOS ranged from 125 to 175 days.Spatially,the earlier SOS,later SOS and longer LOS occurred in the humid and sub\|humid area of the plateau,and later SOS,earlier EOS and shorter LOS occurred in arid and semi\|arid regions of the plateau.Temporally,during the 30\|year observation period,approximately,51.6% and 33.9% of the plateau experienced advanced and delayed SOS,respectively,and 21.2% and 12.4% of which are statistically significant;Approximately,35.6% and 49.8% of the study area experienced delayed EOS,respectively,and 8.2% and 12.0% of which are statistically significant;Accordingly,40.3% (17.8% are significant) and 44.8% (18.9% are significant) of the plateau showed shortening and lengthening of the LOS.     

Preparation of High-Strength Al–Mg–Si/Al_2O_3 Composites with Lamellar Structures Using Freeze Casting and Pressureless Infiltration Techniques

Lamellar porous alumina scaffolds with the initial solid loadings of 20, 25, and 30 vol% were prepared by freeze casting using 5 lm alumina powders. With the addition of 3 wt% Mg O–Al2O3–Si O2 nanopowders in a eutectic composition as sintering aid, the maximum compressive strength of the sintered scaffolds reached(64 ± 2) MPa after sintering at 1,773 K for 2 h. The lamellar porous scaffolds were then filled with a molten Al–12Si–10 Mg alloy(in wt%)by pressureless infiltration at 1,223 K in a N2 atmosphere, yielding the shell-like structure of the composites. The compressive strength of the upper part composite with the initial 30 vol% solid loading reached(1,190 ± 50) MPa, which was about 3.5 times as large as that of the matrix alloy.     

基于端到端的蒙古语异形同音词声学建模方法

蒙古语声学模型的训练过程是模型学习发音数据与标注数据之间关系的一个过程.针对以音素为建模粒子的蒙古语声学模型建模,由于蒙古语词的发音与语义存在一对多映射现象,会造成解码出的蒙古语文本错误,进而导致蒙古语语音识别系统识别率降低的问题.对此,该文以端到端模型为基础,以蒙古语音素、字母为蒙古语声学模型建模粒子,设计了基于BL...     

Samarium‐Promoted Asymmetric Aldol–Tishchenko Reaction: Synthesis of Amino Acid‐Derived 4‐Amino‐1,3‐diols

A samarium‐mediated novel synthesis of enantiopure 4‐amino‐1,3‐diols is carried out through a samarium‐promoted aldol–Tishchenko reaction starting from chiral α′‐amino‐α‐chloro ketones (derived from natural α‐amino acids) and aldehydes. The process takes place with moderate levels of stereoselectivity and in high yields. A mechanism is proposed to explain these results while the absolute configuration and structure of the aldol–Tishchenko adducts were established by X‐ray analysis. This method has also been utilized for the synthesis of enigmols, 1‐deoxysphingoid base analogues.     

A tabu search algorithm for structural software testing

This paper presents a tabu search metaheuristic algorithm for the automatic generation of structural software tests. It is a novel work since tabu search is applied to the automation of the test generation task, whereas previous works have used other techniques such as genetic algorithms. The developed test generator has a cost function for intensifying the search and another for diversifying the search that is used when the intensification is not successful. It also combines the use of memory with a backtracking process to avoid getting stuck in local minima. Evaluation of the generator was performed using complex programs under test and large ranges for input variables. Results show that the developed generator is both effective and efficient.     

Automated test data generation using a scatter search approach

The techniques for the automatic generation of test cases try to efficiently find a small set of cases that allow a given adequacy criterion to be fulfilled, thus contributing to a reduction in the cost of software testing. In this paper we present and analyze two versions of an approach based on the scatter search metaheuristic technique for the automatic generation of software test cases using a branch coverage adequacy criterion. The first test case generator, called TCSS, uses a diversity property to extend the search of test cases to all branches of the program under test in order to generate test cases that cover these. The second, called TCSS-LS, is an extension of the previous test case generator which combines the diversity property with a local search method that allows the intensification of the search for test cases that cover the difficult branches. We present the results obtained by our generators and carry out a detailed comparison with many other generators, showing a good performance of our approach.