水产养殖学特色专业建设的目标定位与建设路径     

傅学丽  张健东 《广东海洋大学学报》2010,30(5)

水产养殖学特色专业的建设是一项系统工程。首先,水产养殖学特色专业建设要正视在水产养殖业发展和水产养殖教育发展过程中出现的矛盾;其次,要为水产养殖学特色专业的建设确定适当的目标;第三,通过对原有教学理念进行创新,对办学模式进行重新构建,对师资队伍进行调整,对教学管理机制进行改革的建设路径实现上述目标。  相似文献   

近断层强地震动场预测   总被引：6，自引：2，他引：4       下载免费PDF全文

王海云  谢礼立 《地球物理学报》2009,52(3):703-711

以1997年4月11日新疆伽师地震（M_w6.1）为例,详细介绍了近断层强地震动场的预测方法.首先,用有限断层震源建模方法建立了该次地震的震源模型;然后,基于动力学拐角频率的地震动随机模拟方法,模拟了该次地震仅有主震加速度记录、且位于巨厚土层上的三个台站的加速度时程,并用实际地震记录进行了验证.在此基础上,基于预测的近断层77个节点的加速度时程的峰值绘制了该次地震的加速度场.结果表明,上述方法模拟的加速度时程在0.5 Hz以上的高频段是可行的、实用的;预测的近断层加速度场具有非常明显的上盘效应.地表最大加速度的范围与断层面上最大凹凸体位置相对应,说明与断层面上凹凸体相对应的地面上的建（构）筑物将会遭受到较为严重的震害.  相似文献   

基于偏最小二乘通径模型的武汉市岩溶塌陷危险性预测          下载免费PDF全文

冯永 《地震工程学报》2008,30(2):128-131

目前对岩溶地面塌陷的研究仍主要在宏观和定性的水平上.偏最小二乘通径模型采用一系列一元或多元线性回归的迭代求解,无需对观测变量做特定的概论分布假设,对样本点容量的要求也十分宽松,不存在模型不可识别的问题,是一种实用和有效的线性统计建模方法.本文在分析武汉市岩溶塌陷影响因素的基础上,基于GIS技术,采用偏最小二乘通径模型对武汉市岩溶塌陷危险性进行了预测.结果表明利用该模型可以取得较好的预测结果,在工程实际应用中有一定的借鉴意义.  相似文献   

气象要素对大豆产量的影响分析   总被引：1，自引：0，他引：1       下载免费PDF全文

刘景利  杨扬  梁涛  史奎桥  张兵兵  张慧  许长华  宋敏  陆刚 《气象与环境学报》2013,29(5):136-139

基于2001-2009年大豆田间试验观测数据,利用相关和通径分析揭示了大豆不同发育期的气象因子和生物因子对大豆产量的影响。结果表明：不同发育期的气象要素对大豆产量影响效果不同,其中开花-结荚期的平均气温与大豆产量相关性最大,为0.90,其次为播种-出苗期的降水,相关系数为0.71,结荚-鼓粒期的相对湿度和日照时数,分枝期的生物量和开花期的叶面积对大豆产量具有一定影响（r>0.5）。通径分析显示具有显著直接作用的因子是开花期的叶面积,不同发育期的气温与降水主要通过对生物量和叶面积的间接作用来影响大豆产量,结荚-鼓粒期的相对湿度和日照时数对产量具有较大的直接作用。耦合气象因子与生物因子建立大豆产量回归模拟方程,能够较好解释大豆产量（R²=0.99）。  相似文献   

地震射线辛几何算法初探   总被引：32，自引：10，他引：22       下载免费PDF全文

高亮  李幼铭  陈旭荣  杨孔庆 《地球物理学报》2000,43(3):402-410

走时计算已广泛用于地震建模、成像及速度分析等诸方面．基于地震波场的Ｈａｍｉｌｔｏｎ力学性质,本文探索应用适于Ｈａｍｉｌｔｏｎ力学的计算方法──辛几何算法对地震射线 进行走时及路径的计算．利用辛几何算法和属于耗散算法的四阶 Ｒｕｎｇｅ－Ｋｕｔｔａ算法进行射线 路径和走时的计算对比,结果表明这两类算法数值精度相当,但辛几何算法的速度却快了３ 倍．本文还利用二阶Ｅｕｌｅｒ型辛差分格式对Ｍａｒｍｏｕｓｉ模型进行了射线追踪计算,结果显示所 得射线具有良好的光滑性和较强的阴影区穿透能力．  相似文献   

Petrology and geochemistry of South Mid-Atlantic Ridge (19°S) lava flows: Implications for magmatic processes and possible plume-ridge interactions     

《地学前缘(英文版)》2020,11(6):1953-1973

The South Mid-Atlantic Ridge (SMAR) 19°S segment, approximately located along the line of Saint Helena volcanic chain (created by Saint Helena mantle plume), is an ideal place to investigate the issue whether the ridge-hotpot interaction process affected the whole MAR. In this study, we present major and trace elemental compositions and Sr-Nd-Pb isotopic ratios of twenty fresh lava samples concentrated in a relatively small area in the SMAR 19°S segment. Major oxides compositions show that all samples are tholeiite. Low contents of compatible trace elements (e.g., Ni ​= ​239–594 ​ppm and Cr ​= ​456–1010 ​ppm) and low Fe/Mn (54–67) and Ce/Yb (0.65–1.5) ratios of these lavas show that their parental magmas are partially melted by a spinel lherzolite mantle source. Using software PRIMELT3, this study obtained mantle potential temperatures (T_p) beneath the segment of 1321–1348 ​°C, which is lower relative to those ridges influenced by mantle plumes. The asthenospheric mantle beneath the SMAR 19°S segment starts melting at a depth of ~63 ​km and ceases melting at ~43 ​km with a final melting temperature of ~1265 ​°C. The extent of partial melting is up to 16%–17.6% with an average adiabatic decompression value of 2.6%/kbar. The correlations of major oxides (CaO/Al₂O₃) and trace elements (Cr, Co, V) with MgO and Zr show that the parental magma experienced olivine and plagioclase fractional crystallization during its ascent to the surface.⁸⁷Sr/⁸⁶Sr (0.702398–0.702996), ¹⁴³Nd/¹⁴⁴Nd (0.513017–0.513177) and ²⁰⁶Pb/²⁰⁴Pb (18.444–19.477) ratios of these lavas indicate the mantle source beneath the SMAR 19°S segment is composed of a three-component mixture of depleted MORB mantle, PREMA mantle, and HIMU mantle materials. The simple, binary mixing results among components from plume-free SMAR MORB, Saint Helena plume and Tristan plume show that asthenospheric mantle beneath the SMAR 19°S segment may be polluted by both Saint Helena and Tristan plume enriched materials. The abovementioned mantle potential temperatures, together with the low Saint Helena (<10%) and Tristan (<5%) components remaining in the asthenospheric mantle at present, show that the physically ridge-hotspot interactions at SMAR 19°S segment may have ceased. However, the trace element and Sr-Nd-Pb isotopically binary mixing calculation results imply that these lavas tapped some enriched pockets left when Saint Helena and/or Tristan plume were once on the SMAR during earlier Atlantic rifted history.  相似文献   

Deformation analysis of shallow penetration in clay     

C. Sagaseta  A. J. Whittle  M. Santagata 《国际地质力学数值与分析法杂志》1997,21(10):687-719

A new method of analysis is described for estimating the deformations and strains caused by shallow undrained penetration of piles and caissons in clay. The formulation combines previous analyses for steady, deep penetration, with methods used to compute soil deformations due to near-surface ground loss, and is referred to as the Shallow Strain Path Method (SSPM). Complete analytical solutions for the velocity and strain rates are given for a planar wall, an axisymmetric, closed-ended pile and unplugged, open-ended pile geometries. In these examples, the analyses consider a single source penetrating through the soil at a constant rate, generating a family of penetrometers with rounded tips, referred to as simple wall, pile and tube geometries. Soil deformations and strains are obtained by integrating the velocity and strain rates along the particle paths. The transition from shallow to deep penetration is analysed in detail. Shallow penetration causes heave at the ground surface, while settlements occur only in a thin veneer of material adjacent to the shaft and in a bulb-shaped region around the tip. The size of this region increases with the embedment depth. Deformations inside an open-ended pile/caisson are affected significantly by details of the simple tube wall geometry. © 1997 by John Wiley & Sons, Ltd.  相似文献   

硫酸盐型盐湖盐田泻利盐矿硫酸镁浸取结晶工艺条件研究          下载免费PDF全文

侯殿保  杨海云  陈育刚  李海民 《盐湖研究》2020,28(2):71-78

本研究利用盐田高硫酸镁混盐矿—泻利盐矿和提钾老卤为原料,通过中温溶浸、冷却结晶的方法制取工业级硫酸镁。盐田高硫酸镁混盐矿热溶浸取最佳配矿条件,泻利盐矿:提钾老卤:淡水=1∶1.8∶0.8,溶浸温度(55±5)℃,溶浸时间1～2 h;将热滤液分别进行自然蒸发和冷冻结晶处理,得到的粗品经水洗均可达到工业级硫酸镁产品标准,采用冷冻结晶法收率较高,达到80.25%。  相似文献   

基于生态文明理念的围填海工程生态化建设重点路径研究     

张翠萍  张绍丽  贾后磊  李珊  王平  张晓浩 《海洋湖沼通报》2019,(2):53-58

本文分析论述了围填海工程生态化建设的必要性和可行性。结合实际调研案例相关工作,提出围填海工程生态化建设的原则,以及生态化过程中海洋生态文明建设落地的重点路径,包括尽量保留原有水系与原始海岸、进行生态化海堤建设、填海前沿生境修复和公众亲海空间打造等四种主要措施。为保障生态化建设措施落实到位和生态建设预期效果,给出了两个建议,一是应将生态文明理念贯穿工程全过程;二是尽快建立生态建设技术规范体系。  相似文献   

基于SVM的气候持续法在热带气旋路径预报中的应用试验   总被引：2，自引：1，他引：1  

吕庆平  罗坚  朱坤  任景鹏 《海洋预报》2009,26(1)

本文利用气候持续性因子,分别采用支持向量机法、神经网络法及最小二乘回归法建立西北太平洋地区12、24、36、48h热带气旋路径预报模型.通过1997～2002年的试报.支持向量机法明显优干回归方法和神经网络法,12h的预报水平分别提高了4.97%和2.75%,而且随着预报时效的延长,这种优势越来越明显,4Sh的预报水平提高了11.92%和7.88%.  相似文献