降雨环境下车身表面水相分布特性

本文建立了汽车外流场空气动力学数值计算模型,结合Lagrangian discrete phase model和Eulerian wall film model两种方法模拟了水相的生成和发展过程。在此基础上,开展不同降雨强度、不同车速条件下的车身表面水相生成计算,研究影响水相分布变化的因素。研究结果表明:在一定的车速和降雨强度条件下,车身水相厚度逐渐增大,最终趋于稳定;当车速一定时,车头、前窗、后窗和侧窗区域水相厚度随降雨强度的增大而增大;当降雨强度一定时,车头、后窗和侧窗水相厚度随车速增大而增大,而前窗水相厚度随车速增大而减小。

不同熟制方式下调理鸡排蛋白质结构及水相分布的变化

为了探究熟制方式对调理鸡排蛋白质结构和水相分布的变化的影响,以预制的调理鸡排为研究对象,用三种不同的熟制方式(香煎熟制、鼓风烤制、普通烤制)进行熟制(生鸡排为对照),测定蛋白质二级结构,观察肌纤维微观结构并分析水分迁移情况。结果表明:蛋白质二级结构中酰胺I带变化量为9.64 cm^(-1)(普通烤制)、11.579 cm^(-1)(鼓风烤制)、13.49 cm^(-1)(香煎熟制);呈凝胶网状的蛋白质微观结构由疏松到紧密的大小为:普通烤制>鼓风烤制>香煎熟制;各组自由水峰面积P23分别为0.31%(生鸡排)、1.85%(普通烤制)、2.97%(鼓风烤制)、3.56%(香煎熟制);系水力大小为:普通烤制>鼓风烤制>香煎熟制。以上结果为明确不同熟制方式对调理鸡排食用品质的影响提供理论指导依据。

rwo-phase pore-fluid distribution in fractured media, acoustic wave velocity vs saturation

The acoustic wave velocity varies with fluid saturation and pore-fluid distribution. We use a P-wave source and the staggered grid finite-difference method, with second-order accuracy in time and eighth-order accuracy in space, to simulate the acoustic wave field in a fractured medium that is saturated with a two-phase pore fluid （gas ＆ water）. Further, we analyze the variation of acoustic wave velocity with saturation for different pore-fluid distribution modes. The numerical simulation method is simple and yields accurate results.

Variation of Thornthwaite Moisture Index in Hengduan Mountains, China

The Thornthwaite moisture index, an index of the supply of water （precipitation） in an area relative to the climatic demand for water （potential evapotranspiration）, was used to examine the spatial and temporal variation of drought and to verify the influence of environmental factors on the drought in the Hengduan Mountains, China. Results indicate that the Thornthwaite moisture index in the Hengduan Mountains had been increasing since 1960 with a rate of 0.1938/yr. Annual Thomthwaite moisture index in Hengduan Mountains was between -97.47 and 67.43 and the spatial heterogeneity was obvious in different seasons. Thomthwaite moisture index was high in the north and low in the south, and the monsoon rainfall had a significant impact on its spatial distribution. The tendency rate of Thomthwaite moisture index variation varied in different seasons, and the increasing trends in spring were greater than that in summer and autumn. However, the Thomthwaite moisture index decreased in winter. Thomthwaite moisture index increased greatly in the north and there was a small growth in the south of Hengduan Mountains. The increase of precipitation and decrease of evaporation lead to the increase of Thomthwaite moisture index. Thornthwaite moisture index has strong correlation with vegetation coverage. It can be seen that the correlation between Normalized Difference Vegetation Index （NDVI） and Thomthwaite moisture index was positive in spring and summer, but negative in autumn and winter. Correlation between Thornthwaite moisture index and relative soil relative moisture content was positive in spring, summer and autumn, but negative in winter. The typical mountainous terrain affect the distribu- tion of temperature, precipitation, wind speed and other meteorological factors in this region, and then affect the spatial distribution of Thomthwaite moisture index. The unique ridge-gorge terrain caused the continuity of water-heat distribution from the north to south, and the water-heat was stronger than that from the east to west part, and thus determined the spatial distribution of Thornthwaite mois- ture index. The drought in the Hengduan Mountains area is mainly due to the unstable South Asian monsoon rainfall time.

Relationship between zonal position of the North Atlantic Oscillation and Euro-Atlantic blocking events and its possible effect on the weather over Europe

The North Atlantic Oscillation(NAO) exhibited a marked eastward shift in the mid-1970 s. Observations show that the extreme weather events in Europe have emerged frequently in the past decades. In this paper, based upon the daily NAO index, we have calculated the frequency of in-situ NAO events in winter during 1950-2011 by defining the Eastern-type NAO(ENAO) and Western-type NAO(WNAO) events according to its position at the east(west) of 10°W. Then, the composites of the blocking frequency, temperature and precipitation anomalies for different types of NAO events are performed. Results show that the frequency of Euro-Atlantic blocking events is distributed along the northwest-southeast(southwest-northeast) direction for the negative(positive) phase. Two blocking action centers in Greenland and European continent are observed during the negative phase while one blocking action center over south Europe is seen for the positive phase. The action center of blocking events tends to shift eastward as the NAO is shifted toward the European continent. Moreover, the eastern-type negative phase(ENAO) events are followed by a sharp decline of surface air temperature over Europe(especially in central, east, and south Europe), which have a wider and stronger impact on the weather over European continent than the western-type negative phase(WNAO) events do. A double- branched structure of positive precipitation anomalies is seen for the negative phase event, besides strong positive precipitation anomalies over south Europe for ENAO event. The eastern-type and western-type positive phase(ENAO+ and WNAO+) can lead to warming over Europe. A single-branched positive precipitation anomaly dominant in central and north Europe is seen for positive phase events.