黄海区虾拖网网囊网目选择性研究   总被引：1，自引：0，他引：1  

唐衍力  孙国微  杨炳忠  赵同阳  黄六一  梁振林 《中国海洋大学学报(自然科学版)》2010,40(10)

在黄海区的山东近海,采用套网法对网目尺寸为30,33和40 mm的虾拖网网囊进行了选择性试验。使用Lo-gistic曲线作为选择性模型,求得不同网目尺寸的网囊对鹰爪虾(Trachypenaeus curvirostris)的体长选择性曲线,并运用极大似然法对渔获数据进行处理,同时估算选择性参数。结果表明,在网目尺寸为30,33和40 mm时主捕虾类鹰爪虾的选择体长L50分别为59.8,60.1和63.2 mm,选择范围SR分别为14.4,16.0和22.9 mm,选择性参数随网目尺寸的增加呈线性增大。鹰爪虾的选择体长L50与网囊网目尺寸m的线性回归方程为L50=0.353m+48.944,R2=0.956。根据试验结果并结合历史资料,认为目前33 mm的网囊网目尺寸对于保护鹰爪虾类资源是比较合适的。  相似文献   

Correlation Between Total Lightning Activity and Precipitation Particle Characteristics Observed from 34 Thunderstorms     

ZHENG Dong  MENG Qing  ZHANG Yijun  DAI Jianhu  ZHONG Min 《Acta Meteorologica Sinica》2010,24(6):776-788

A total of 34 thunderstorms around Shanghai and Wuhan of China are analyzed in order to determine the relationship between total lightning activity and precipitation particle characteristics.Precipitation particle concentration data are obtained from the 2A12 product of TRMM/TMI(Tropical Rainfall Measuring Mission/TRMM Microwave Image) and lightning activity data are from the TRMM/LIS(Lightning Imaging Sensor) and SAFIR3000(Surveillance et Alerte Founder par Interferometric Radioelectirque).On a spatial ...  相似文献   

Effects of Initial Stresses in Tailored Pulse Loading Method     

Wang Jingtao  Lin Jiqing  Sun Shangxin  Dong Chengquan 《岩土力学》1988,9(3):1-10

Based on the mechanism study of new well stimulation method—tailored pulse loading method, the effects of initial stresses in this method is further studied. The effects of initial stresses on the propagation velocities and directions of the cracks around a hole, especially on the energy dissipation in crack extension, are obtained through theoretical analysis, dynamic photo elasticity tests, high speed photography. And large coal specimen tests. These results provide a theoretical foundation for the practical applications of the tailored pulse loading method.  相似文献   

徐湾—石头岗花岗闪长岩体对围岩的热影响     

朱雄飞  茆德俊  肖深耀  董传万 《吉林大学学报(地球科学版)》1989,(4)

对徐海—石头岗花岗闪长岩体围岩中黑云母及有机质变质程度的研究发现:距岩体580m范围内的接触带岩石皆具有角岩化现象。黑云母含量受原岩成分影响,其鳞片粒径与岩体距离密切有关。围岩中镜质组反射率,(R_(mas))值与岩体距离之间有十分明显的规律。  相似文献   

Tectonodynamic Adjustment of Crustal Materials in the Middle-Lower Reaches of the Yangtze River1     

Dong Shuwen 《《地质学报》英文版》1989,2(4):325-342

Abstract Under the tectonodynamic process, crustal materials tend to experience two modes of adjustment: (1) structural (physical) adjustment, manifested by folding, faulting, uplifting, downwarping, etc.? (2) compositional adjustment, represented by element migration, concentration and dispersion, crystalline and dynamic differentiation of crystals, metamorphism, etc. (Yang Kaiqing, 1986; Yang Kaiqing et al., 1986). The dynamic adjustment of crustal materials in the middle- lower reaches of the Yangtze mainly occurred in the Mesozoic under the conditions of intense collision between the North China (Dabie) massif and the Yangtze massif. The structural adjustment refers to various types of deformation within the two massifs and the intensive shortening of the stratigraphic cover of the Yangtze massif, whereas the compositional adjustment implies the structural remelting of the basement and the ore- and rock- forming processes in the two massifs.  相似文献   

应用Bayes算法估计核函数误差对大气温度廓线反演的影响   总被引：2，自引：2，他引：2  

黎光清  董超华 《大气科学》1988,12(1):36-41

核函数的误差(简称KFE)是引起反演方程数值解不稳定的根本原因之一,也是物理反演法用于TOVS资料业务处理的基本障碍。本文基于Bayes算法和考虑KFE的适当统计假定,导出了估计KFE效应的方法。使用NOAA-7气象卫星测值,依据NFSDIS透过率资料算出的核函数,以及两年二月气候资料计算的协方差矩阵等数据,按此方法估计了KFE效应对温度廓线反演精度的影响,并对KFE引起反演解中的系统偏差和随机误差分量也作了定量计算,揭示出了系统偏差在非适定问题解中的主导作用。  相似文献   

El Nino/Southern oscillation signals in the global tropical ocean     

Fu Congbin  Dong Dongfeng  Ralph Slutz  Joseph Fletcher 《大气科学进展》1988,5(1):35-46

The monthly mean sea surface temperature data of 6 areas are used to study the El Nino/Southern Oscillation signals in the global tropical ocean. These areas are in the 5oN-5oS latitude zone at 1) eastern Pacific (110o-l40oW), 2) western Atlantic (30o-50oW), 3) eastern Atlantic (10oW-10oE), 4) western Indian Ocean (30o-50oE), 5) central Indian Ocean (70o-90oE) and 6) far western Pacific (120o-140oE), and the data cover the 120-month period of December 1968 to November 1978.A power spectrum analysts shows that the characteristic time of the El Nino/Southern Oscillation (about 3-4 years) appears not only in the eastern Pacific but also in other areas of the tropics except for the western Pa-cific, where the spectrum is of white noise. The amplitude of oscillation in the eastern Pacific is about 4 times larger than the others, making the El Nino/Southern Oscillation signal the strongest in this area. According to a cross-spectrum analysis, there is no time lag between the variation in the central Indian Ocean and that in the eastern Pacific. These two areas oscillate simultaneously and comprise the main feature of the El Nino/ Southern Oscillation. Other tropical areas are related with time lags, as shown by correlation and coherence calculations.It should be noted that the sea surface temperature in the eastern Pacific oscillates in phase with that in the Indian Ocean, while the pressure oscillations in these two areas are out of phase with each other, according to the Southern Oscillation definition. It is suggested that the Southern Oscillation cannot be explained simply by the sea surface temperature anomalies.Variations in the far western equatorial Pacific do not have the time scale of the El Nino/Southern Oscilla-tion, perhaps because it is a buffer zone between the monsoon system and the trade wind system.  相似文献   

云南新平县双沟蛇绿岩稀土元素地球化学研究   总被引：5，自引：0，他引：5       下载免费PDF全文

黄忠祥  韩松  董金泉  贾秀勤  张旗  赵大升 《岩石矿物学杂志》1993,12(3):205-212

双沟蛇绿岩中,变质橄榄岩的REE分布型式为LREE富集型,可能是富大离子亲石元素(LILE)组分交代造成的。地幔岩部分熔融生成的初始熔体LREE亏损,而辉绿岩和玄武岩则存在LREE亏损和富集两种型式,前者相当于N-MORB,后者相当于E-MORB。推测前者来源于亏损的软流圈地幔,而后者的地幔源区经历过一次富集LREE和LILE的事件。双沟蛇绿岩的REE特征暗示它可能形成于弧后盆地。  相似文献   

钙钛矿型结构亚硝酸盐和氰化物的分子体积          下载免费PDF全文

董麒  叶大年 《地质科学》1993,28(1):44-51

绝大部分的亚硝酸盐和氰化物属于钙钛矿型结构,但有部分化合物为“反”钙钛矿型结构,充填空洞A位的阳离子的拓扑体积为0。阴离子团NO₂^-和CN^-的拓扑体积都近乎常数,分别为41.73ų和40.03ų,标准方差σ_n-1=1.516和σ_n-1=1.25。由此,进一步证明了原来的一套离子拓扑体积数值的普适性。“反”钙钛矿型结构中A位阳离子的平均半径r_A>1.00Å时,三价阳离子会产生扩容效应,其扩容系数大约是其本身拓扑体积的2倍;正钙钛矿型结构中,当A位是由半径较大的Cs⁺充填时,Cs⁺也会产生扩容效应,其扩容系数约为24ų。氰化物中结晶水分子的拓扑体积近乎常数,为24ų或0。  相似文献   

贝勒库都克锡矿带地质特征与成因     

毕承思  沈湘元  徐庆生  明奎海  孙惠礼  张春山 《地球学报》1993,14(3):51-66

贝勒库都克锡矿带是我国新发现北方地区第一条独立锡矿带．由与S型黑云母花岗岩有关的石英脉型锡矿及与A型花岗岩伴生的锡矿床和砂锡矿组成其成矿系列。成矿时代属海西晚期。准噶尔与野马泉两地块相撞焊接．于碰撞褶皱带形成区域造山期花岗岩．热量聚集熔化产生改造型含矿花岗岩株，局部拉张产生含矿A型花岗岩，二者经碱质交代-酸性淋滤成矿作用，使锡活化迁移集中富集而形成有关锡矿床。  相似文献