Retrieval of balanced fields: an optimal control method   总被引：1，自引：0，他引：1  

FRANÇOIS-XAVIER LE DIMET  MOHAMED OUBERDOUS 《地球，A辑:动力气象学与海洋学》1993,45(5):449-461

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Lateglacial landform associations at Jæren (SW Norway) and their glaci-dynamic implications     

STÅLE RAUNHOLM  HANS PETTER SEJRUP  EILIV LARSEN 《Boreas: An International Journal of Quaternary Research》2003,32(3):462-475

The Jæren lowland is located on the southwestern coast of Norway between a mountainous region in the east and the offshore Norwegian Channel in the west. During the Last Glacial Maximum, Jæren was in an intermediate position between an ice stream following the Norwegian Channel northwards, and westward flowing inland ice. The dynamic behaviour of the inland ice and the interaction with the ice stream are examined by means of geomorphological analysis of digital terrain models and sedimentological investigations. SW-trending drumlins were formed at Jæren below tributary ice from the inland, feeding into the Norwegian Channel Ice Stream. The presence of Rogen moraine in the central part of Jæren indicates a frozen substratum prior to their formation, and this suggests a transition to cold-based ice between the tributaries. The deglaciation of the Norwegian Channel at about 15 ka BP resulted in an unstable ice front for the inland ice sheet. The formation of Rogen moraine may be explained by a dynamic advance resulting in extensional flow and fracturing of the frozen substratum between the tributaries. The dynamic advance was followed by an early deglaciation of the coastal areas as evidenced by shallow marine sediments. Deformation of the shallow marine sand indicates a glacial readvance through the valleys formerly acting as tributaries to the ice stream.  相似文献   

辽宁沿海经济带工业环境效率分析   总被引：10，自引：3，他引：7  

佟连军  宋亚楠  韩瑞玲  李名升 《地理科学》2012,(3):294-300

环境效率是生态效率的重要组成部分。基于环境效率对于指导区域经济与环境协调发展的重要意义,以重工业基地辽宁沿海经济带为例作环境效率研究,应用数据包络分析(DEA)和随机前沿分析(SFA)测算辽宁沿海经济带2001~2009年工业环境效率和产出弹性。在此基础上利用Tobit模型构建多元线性回归,分析工业环境效率的关键影响因素。结果表明:2001~2009年辽宁沿海经济带工业环境效率有大幅提高,但与理想状况仍有一定差距。其中大连的工业经济增长主要依靠劳动力推动,对环境成本的依赖正在减小,丹东、营口和葫芦岛3市的工业增长需要牺牲更多的环境成本。重工业化、资本密集化和高新技术化不利于工业环境效率提高,经济发展水平的提高则极大地促进了工业环境效率的提高。所有制结构、生产规模、外商投资和环境管理力度等因素因其作用的两面性,对工业环境效率无有效影响。  相似文献   

利用窄线宽激光测量锶原子束速率分布     

赵亚楠  吴慧  常宏  张首刚 《时间频率学报》2009,32(1):1-5

利用多普勒频移效应,通过线宽2MHz窄线宽激光与锶原子束在大角度作用下的荧光信号分析,测量了锶原子束速率分布。比较和分析表明,理论结果与实验结果符合较好。  相似文献   

Valence state partitioning of V between pyroxene‐melt: Effects of pyroxene and melt composition,and direct determination of V valence states by XANES. Application to Martian basalt QUE 94201 composition     

J. M. KARNER  J. J. PAPIKE  S. R. SUTTON  C. K. SHEARER  P. BURGER  G. McKAY  L. LE 《Meteoritics & planetary science》2008,43(8):1275-1285

Abstract— Experiments on a Martian basalt composition show that D_v augite/melt is greater than D_v pigeonite/melt in samples equilibrated under the same fO₂ conditions. This increase is due to the increased availability of elements for coupled substitution with the V³⁺ or V⁴⁺ ions, namely A1 and Na. For this bulk composition, both A1 and Na are higher in concentration in augite compared with pigeonite; therefore more V can enter augite than pigeonite. Direct valence state determination by XANES shows that the V³⁺ and V⁴⁺ are the main V species in the melt at fO₂ conditions of IW‐1 to IW+3.5, whereas pyroxene grains at IW‐1, IW, and IW+1 contain mostly V³⁺. This confirms the idea that V³⁺ is more compatible in pyroxene than V⁴⁺. The XANES data also indicates that a small percentage of V²⁺ may exist in melt and pyroxene at IW‐1. The similar valence of V in glass and pyroxene at IW‐1 suggests that V²⁺ and V³⁺ may have similar compatibilities in pyroxene.  相似文献   

羌北-昌都地块那益雄组火山岩锆石U-Pb年代学及地球化学特征     

张锦  程鑫  高扬  李玉玉  朱亚林  周亚楠  吴汉宁 《岩石矿物学杂志》2019,38(1):77-89

本文对青藏高原羌北-昌都地块阿布日阿加措地区的晚二叠世那益雄组火山岩进行了年代学和地球化学研究。该火山岩主要由玄武岩、安山玄武岩、安山岩、流纹岩、凝灰岩组成,具有碱性玄武岩到酸性熔岩的特征。锆石U-Pb年代学研究表明该火山岩的形成时代为251. 1±4. 8～249. 6±1. 3 Ma之间。地球化学分析结果表明,该地区的流纹岩具有高的Si O2(74. 85%～77. 55%)和Na2O+K2O(5. 40%～6. 61%)含量,较低的MgO、K2O和Ca O含量,Al2O3含量低且稳定,里特曼指数平均为1. 15,小于3. 3。安山岩Si O2含量55. 13%～56. 28%,Na2O+K2O含量4. 13%～6. 15%,里特曼指数平均为2. 20,小于3. 3,属于钙碱性安山岩。碱性玄武岩Si O2含量51. 49%,Na2O+K2O含量6. 34%,里特曼指数为4. 73,属于碱性系列。稀土元素配分曲线为富集LREE的右倾型。另外,富集大离子亲石元素(LILE) Th、U,亏损高场强元素(HFSE) Nb、Ta等特征,均说明羌北-昌都地块阿布日阿加措地区的火山岩形成于陆缘岛弧环境。  相似文献   

微生物诱导碳酸盐沉积改善裂隙岩石防渗性能和强度的试验研究     

邓红卫  罗益林  邓畯仁  伍礼杰  张亚南  彭述权 《岩土力学》2019,(9):3542-3548,3558

微生物诱导碳酸盐沉积(MICP)技术主要利用微生物生命活动与环境反应形成的碳酸盐来修复岩土体。为了研究该技术改善含裂隙岩石防渗性能和强度的效果,利用巴氏芽孢杆菌开展了裂隙黄砂岩的修复试验,并对修复后的裂隙黄砂岩进行了无侧限抗压、核磁共振和电镜扫描(SEM)等测试,分析了巴氏芽孢杆菌对裂隙黄砂岩的修复效果和修复机制。研究表明:巴氏芽孢杆菌对裂隙黄砂岩具有较好的修复效果;修复时间越长,巴氏芽孢杆菌的修复效果越好。修复42d后,裂隙黄砂岩的孔隙率下降36.41%,防渗性能提升94.62%,抗压强度增加30.52%。巴氏芽孢杆菌具有较好修复效果原因在于,其诱导产生的碳酸钙能够胶结填充物与试样,大幅降低试样的孔隙率,改善其内部孔隙结构的均质性。  相似文献   

平顶山城区碳环境演变时间序列分析     

宋亚男 《测绘与空间地理信息》2017,(4)

大气中日益上升的温室气体浓度,已导致温室效应日益增强,从而引发一系列不利的环境与生态后果,并会对世界粮食生产、水资源利用等关系人类生存发展的方面产生重要影响。1994~2014年是平顶山城市化进程不断加快和经济社会高速发展的时期,土地利用、人口、能源消耗和城市植被等影响碳源、碳汇的主要方面也都发生了重大的变化。将1994~2014年河南省平顶山市城区的碳平衡变化情况作为研究对象,计算出碳平衡主要影响因素各自的变化情况并加以分析,得出有关平顶山城区碳环境演变的结论。最后,为促进平顶山城区的碳源碳汇平衡,提出实现城市快速发展过程中低碳效应策略。  相似文献   

Partially Fused Granite Blocks from Mt. Elephant, Victoria, Australia     

LE MAITRE  R. W. 《Journal of Petrology》1974,15(2):403-412

Petrological and chemical evidence is presented to show thatsmall patches of brown glass found in blocks of granite eruptedin basaltic scoria at Mt. Elephant are the result of the partialfusion of biotite and quartz. The glass has moderate SiO₂ (63–66per cent), high AI₂O₃ (17.5–19 per cent), high FeO (3.8–5.2per cent) and very high K₂O (7.0–7.8 per cent) relativeto Na₂O (3.3–3.7 per cent) and is similar in compositionto many high K alkali syenites and trachytes.  相似文献   

考虑流固耦合效应的单桩式海上风电机组结构响应模拟     

乐可定  郁冶  赵兰浩  牟凯龙 《海洋工程》2023,41(5):37-47

针对海上风电整机系统,建立了一体化流固耦合分析方法。在模拟过程中,采用浸入边界法解决风机叶片旋转引起的静动干涉问题,利用改进的守恒式 level set（简称 ICLS）方法捕捉海浪自由面,并使用交错迭代法求解流固耦合方程。通过构建 “风机—塔架—基础”一体化流固耦合数值模拟方法,能够在一次仿真计算中实现海上风电整机系统的全过程数值模拟,准确求解多荷载耦合作用下“风机—塔架—基础”的整体结构动力响应。以某单桩式海上风电工程为例,验证了本方法能够实现对海上风电整体系统的一体化分析。  相似文献