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31.
利用河北省及邻近区域73个气象站1961—2009年逐年降水资料,同期NCEP/NCAR再分析资料,NOAA太平洋海温等资料,分析了河北省干旱的时空变化特征,并应用奇异值分解、合成分析等方法,研究了河北省典型旱涝年份与同期太平洋海温场和环流场的异常特征.结果表明:河北省旱涝异常的空间型分布主要有2种,这些空间型的时间变化除了具有明显的年际变化外,还存在显著的年代际变化.SVD(奇异值分解)分析揭示的河北省旱涝和海气异常的关系表明,当赤道东太平洋年平均海温异常偏低,北太平洋海盆中部年平均海温异常偏高的年份,河北省大部分地区容易偏涝,反之,易干旱.典型干旱年,500hPa平均高度场上贝加尔湖西南部以及极地500 hPa年平均高度场为正异常,阿留申地区南部为负异常;亚洲中高纬地区环流从西到东呈现-+-的环流异常纬向分布.而典型雨涝年500 hPa平均高度场上贝加尔湖西南部以及极地500hPa年平均高度场为负异常,阿留申地区南部为正异常;亚洲中高纬地区环流从西到东呈现-+的环流异常纬向分布. 相似文献
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随着信息化技术在武器上的不断应用和发展,发射场试验能力与武器系统对发射场的要求之间形成了严重的矛盾。为解决这些矛盾,提出了基于HLA网络的数字化发射场建设方案,并对数字化发射场的特点、功能、作用、优点等进行了论述。通过对数字化发射场的组成及体系结构的论证,指出了建设数字化发射场所需要的关键技术。同时,针对数字化发射场的运作模式,提出了未来的研究方向。 相似文献
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The influence of submerged entry nozzle clogging on the behavior of molten steel in continuously cast slab molds was studied using commercial code CFX4.3. The results indicate that clogging at the top part of the nozzle port not only increases the velocity of molten steel, but also enhances the wall shear stress, F number and heat flux. This clogging has the greatest effect on the behavior of molten steel. However, clogging at the top 1/3 of the nozzle only increases the velocity of molten steel and has little influence. Clogging at the bottom of the nozzle almost has no influence. 相似文献
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翻斗式自记流量计从工作原理的角度看,属于容积式流量计的一种,但从应用范围看,又与目前各种形式的容积式流量计均有所不同。目前传统的容积式流量计主要应用于有压管道情况,而翻斗式自记流量计主要应用于各种无压、低水头、小流量的地表和地下径流的监测。本文针对水文科学中有关无压、低水头、小流量的地表和地下径流的监测手段较为落后的局面,在分析翻斗式自记流量计基本构成、工作原理及可应用领域的基础上,重点对其制作工艺和应注意的问题进行了详细介绍与说明,旨意能够起到抛砖引玉的作用,提高我国水文监测的水平。 相似文献
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The problem of measuring exterior ballistic feature points is always difficult to solve and it is essentiale on exterior ballistic measurement. By analysis of radar reflection characteristics and non-stationary echo signals of exterior ballistic feature points, the echo data of exterior ballistic feature points is measured by using the continuous wave radar. The parameters of feature points are extracted by the empirical mode decomposition method (EMD) of Hilbert-Huang transform (HHT) spectrum analysis technique. The radar echo signal model and EMD extraction model are established to analyze the exterior ballistic mutation point detection and EMD extraction method of aliasing echo signal. Typical feature point parameters of exterior ballistic in rocket flight tests are carried out and the effectiveness of the method is verified. A new method of measuring the parameters of exterior ballistic feature point is therefore presented. 相似文献
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Novel microspheres (CPs) composited by rigid and flexible polymers are synthesized and embedded in the supporting membranes to enhance both the skin–substrate adhesion and compaction resistance of the thin‐film composite (TFC) nanofiltration membranes. The CPs are in situ formed in the casting solution after the rigid poly(p‐phenylene terephthamide) (PPTA) is produced in the flexible poly(m‐phenylene isophthalamide) (PMIA) solution. Then the PPTA/PMIA in situ blending membranes are prepared by using the NIPs method, and the TFC NF membranes are fabricated via interfacial polymerization on them. The CPs are characterized via polarizing microscopy and TEM. The surface morphology and chemical composition of the blended membranes are characterized by using FESEM, AFM, FTIR, and WCA, respectively. As the results show, the supporting membrane with higher PPTA content exhibits higher permeability, thermal stability, and compaction resistance. Moreover, the adhesion strength between the TFC functional layer and the supporting membrane is improved significantly. It is proposed that this improvement can be attributed to the CPs that are exposed on the top surface of the supporting membrane, which leads to a great enhancement because of the anchoring effect between the functional layer and the CPs. 相似文献
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Yiting Zhou Wanjun Yang Guanghong Zhou Xinglian Xu Zhigang Zhang Muhammad Ijaz Ahmad Chunbao Li 《International Journal of Food Science & Technology》2017,52(12):2684-2694
To investigate the effect of long‐term storage on in vitro protein digestion of the retort‐pouched pork belly. The products were stored at 25 °C for 0, 30, 60 and 120 days and digested with pepsin and trypsin at each time point. SDS‐PAGE and LC‐MS‐MS were applied to separate and identify proteins and their digested products. In vitro protein digestibility decreased from 47.7% after 60‐day storage to 25.4% after 120‐day storage for the samples digested by pepsin, and from 63.9% to 45.7% for the samples digested by pepsin and trypsin at corresponding time points. LC‐MS‐MS demonstrated changes in peptide composition and abundance with storage time. Long‐term storage could deteriorate nutritive values of meat products by reducing digestible protein content. 相似文献