The hydrological influence of black locust plantations in the loess area of northwest China

Black locust (Robina pseudoacacia) has become one of the most important shelter species in the loess area of northwest China. This paper summarizes recent research concerning its hydrological influence, including canopy interception, litter absorption capacity, its effect on rainfall kinetic energy, infiltration rates, surface runoff, soil moisture, and evapotranspiration, and its role in soil conservation. Several predictive models are listed. on the basis of existing results, optimum characteristics for an effective plantation are defined, and problems requiring further research are identified.     

水牛蹄型深海集矿机履齿设计及牵引性能研究

作为深海采矿系统的重要组成部分,深海集矿机的技术研究和开发一直是许多国家的难题。为了提高深海集矿机在稀软沉积物上的牵引性能,基于水牛蹄的曲面结构特征和特殊几何结构,设计了一款仿水牛蹄蹄型履齿。以该款履齿的结构参数为研究对象,通过对朗肯被动土压力理论的优化,得到了仿水牛蹄蹄型履齿的牵引力解析解,建立了对应的履齿仿生参数对履齿牵引力的影响公式。结合正交试验方法进行了不同形式履齿在沉积物上运动的单、多履齿剪切试验,将仿水牛蹄蹄型履齿与直型履齿、仿水牛蹄轮廓履齿（另一种仿生履齿）进行对比试验,并通过模型车试验验证了该款履齿的可行性。结果表明：3种履齿中,仿水牛蹄蹄型履齿提供的最大牵引力最高。研究可为进一步优化仿水牛蹄蹄型履齿结构参数和提高深海稀软底质机械的牵引性能提供参考依据。     

中国及其邻区周围板块作用力的研究

给出了如何根据观测的应力方向,利用平滑方法处理为在规则格点上均匀分布的数据的过程,并利用新编的中国及其邻区地震震源机制解推断的观测应力方向,反演了周围板块作用力的相对大小．结果表明,在周围三大板块中,以印度板块的作用力最大;其次是太平洋板块;而在菲律宾海板块边界上,作用力大小差异较大,其中又以与台湾相邻的边界段受力最大,琉球岛弧受力最小．     

Occurrence and Distribution of Organic Contaminants in the Aquatic System in Berlin.Part II: Substituted Phenols in Berlin Surface Water

In a surface water screening, 30 representative surface water samples collected from rivers, canals, and lakes in Berlin were investigated for the presence of 22 substituted phenols. The phenols selected include the 11 phenols considered as “priority pollutants” by the US Environmental Protection Agency (US-EPA). Surface water samples were extracted applying solid-phase extraction with styrenedivinylbenzene adsorbent. The recoveries, determined in spiking experiments, were between 80 % and 103 %. After derivatization with N-(tert-butyldimethylsilyl)-N-methyl-trifluoroacetamide (MTBSTFA) the samples were analyzed by capillary gas chromatography-mass spectrometry (GC-MS). Phenol, cresols, 2-ethylphenol, 2-chlorophenol, 4-chloro-3-methylphenol, pentachlorophenol, 2-nitrophenol, and 4-nitrophenol were detected in the surface water samples at concentrations between 0.02 μg/L and 7.8 μg/L, respectively. The distribution of these residues in the Berlin surface waters showed that the phenolic residues, with the exception of pentachlorophenol and 2-ethylphenol, do not originate primarily from municipal sewage treatment plants discharges. Some of the phenols are formed naturally or occur as ubiquitous anthropogenic contaminants in the aquatic system.     

青藏高原积雪的分布特征及其对地面反照率的影响

通过对１９８３年７月至１９９０年６月青藏高原主体５８个格点积雪资料进行ＥＯＦ分析发现，青藏高原主体积雪分布以西部兴都库什山脉。天山山脉以及南部喜马拉雅山脉为主；高原中部唐古拉山脉、北部昆仑山脉和东部巴颜喀拉山脉的积雪相对较少，青藏高原西部、南部的积雪变化与中部、北部和东部的积雪变化趋势存在反位相关系。另外，本文还对积雪对高原地面反照率的影响作了简单分析。     

基于多体分析的浅水FPSO和水下软钢臂系泊系统运动特性研究

基于多体动力分析方法进行FPSO和水下软钢臂系泊系统的运动特性研究。相较于非线性弹簧模拟软钢臂系泊系统或者其他近似模拟方法,多体分析方法可以充分考虑系泊系统具体结构形式及其动力项对FPSO运动性能的影响,更好的预报系统运动响应和系泊力。本文将FPSO和水下钢臂结构模拟成2个具有6自由度的独立结构,两者用系泊链组进行连接。基于三维势流理论应用汇源分布法,首先在频域内进行FPSO的水动力参数分析,进而在时域内对系统进行耦合动力分析。本文重点讨论系泊系统黏性力和二阶波浪力对系统响应的影响,计算结果发现系泊系统黏性力对系泊力有一定影响,而在浅水条件下二阶波浪力的计算对准确预报系统运动及系泊力非常重要。     

“暖池”表层对大气局地强迫的响应特征

利用湍流动能垂直混合模式和ＴＯＧＡ－ＣＯＡＲＥ加强观测期的观测资料,对“暖池”上混合层的垂直混合过程进行数值试验和数值模拟,分析表层温度、盐度的变化特征。结果表明：ＴＫＥ模式可以较好地模拟混层,尤其是表层温度、盐度对大气局地强迫的响应;太阳辐射是热源,感热、潜热通量等会造成“暖池”上混合层的温度降低,“暖池”对大气释放热量;降水有利于“淡水盖”形成和维持,从则使层结稳定,ＳＳＴ升高。但在气温低于海     

基于恒速压汞技术研究页岩气储层孔隙结构:以湘西北地区五峰组页岩为例

页岩气储层孔隙结构是页岩气富集成藏、储层评价和优选有利区的关键参数,区分孔隙和喉道是表征页岩气储层孔隙结构的关键。本文选择4块具有不同渗透率的湘西北地区奥陶系五峰组页岩为研究对象,基于恒速压汞实验讨论孔隙和喉道的大小、分布特征及其相互关系以及与渗透率的联系。结果表明:具有不同渗透率的页岩样品表现为较为相近的孔径分布特征但差异较大的喉道分布特征。页岩样品渗透率的大小与孔隙半径没有明显相关关系;喉道大小及其分布特征是控制低渗储层孔隙结构的关键要素之一。渗透率较低页岩样品的喉道以喉道半径小且集中分布为特征,而渗透率较大页岩样品的喉道以喉道半径大呈分散分布但主要以大喉道为特征。喉道特征是研究页岩气储层储集空间和吸附能力的重要部分,在以后对页岩气的勘探开发中应特别注意及重视。     

不同因素对排水沟渠水平冻胀力的影响

多年冻土地区的排水沟渠经常遭受水平冻胀力的破坏,严重影响构筑物的服役性能。根据青藏高原多年冻土区路基坡脚U型槽排水沟渠的现场试验,并通过数值计算与理论分析,分析了结构埋深、粗颗粒换填范围以及结构形式对其温度场和水平冻胀力的影响。结果表明：改变工况,对土体温度场分布的形状影响较小,仅对其大小有一定影响。不同工况下水平冻胀力均沿深度非均匀分布,最大水平冻胀力主要出现在结构中部,而其上部和下部较小,结构侧壁在1/2至1/3处易发生冻胀破坏。梯形结构所受的水平冻胀力较U型结构增大13%～15%左右,但其分布形式基本相同。因此,U型结构在降低水平冻胀力方面优于梯形结构。随着换填范围增大,排水沟渠的水平冻胀力最大值逐渐减小;对于埋深1.7 m的排水沟渠来说,其侧边的0～2.8 m是影响水平冻胀力的主要换填宽度范围,而当换填宽度超过2.8 m后,水平冻胀力几乎不再降低。     

Spectral Analysis of Nonlinear Drag Forces

The spectral properties of nonlinear drag forces of random waves on vertical circular cylinders are analyzed in this paper by means of nonlinear spectral analysis. The analysis provides basic parameters for estimation of the characteristic drag forces. Numerical computation is also performed for the investigation of the effects of nonlinearity of the drag forces.The results indicate that the wave drag forces calculated by linear wave theory are larger than those calculated by the third order Stokes wave theory for given waves. The difference between them increases with wave height. The wave drag forces calculated by use of hnear approximation are about 5% smaller than their actual values when measured in the peak values of spectral densities. This will result in a safety problem for the design of offshore structures. Therefore, the nonlinear effect of wave drag forces should be taken into comidemtion in design and application of important offshore structures.