中地壳的地球化学动力学和矿石成因

笔者重点进行了大于300℃——在近临界区至超临界区条件下的硅酸盐矿物与水反应动力学实验。矿物(钠长石Ab、透辉石Di、阳起石Act和磁铁矿Mt)的溶解反应动力学实验是使用流体通过叠层反应器的开放体系在25～400℃和22MPa下完成的。实验发现矿物在300℃至400℃范围,在跨越水临界点时出现反应速率的涨落。各种多金属氧化物硅酸盐与水反应时,各个元素溶解到溶液里的释放速率一般不一样,常称为一致溶解作用。但是,在近300℃变为一致溶解作用。实验发现在22MPa时硅酸盐矿物的最大溶解反应速率多是在300℃,如硅的最大释放速率是在300℃。其余元素如Na、K、Mg、Ca、Fe、Al等释放速率在<300℃22MPa时都高于硅的释放速率,在>300℃时硅的释放速率要高于其它元素的释放速率。确切地说,金属与氧之间的键的性质决定了它们(金属氧化物)与水之间反应速率。在一般情况下,Na-Obr,Ca-Obr,Mg-Obr,Al-Obr和Si-Obr的键桥(br),它们之间相对地由具有离子键性质逐步变为具有极性键的性质。由常温常压到亚临界区(300～374℃22MPa),再到大于临界点374℃、22MPa进入超临界区,水的性质随温度、压力变化。水由容易溶解离子键逐渐变为容易打破极性键。笔者还研究了黑钨矿、锡石(玄武岩、花岗闪长岩)与水在250～400℃条件下的反应动力学过程,得出了相同的结果。实验均发现在跨越水临界点时矿物(或岩石)与水反应的动力学涨落。这些实验结果可以用于说明中地壳上部的水/岩相互作用的特征。发生于中地壳的水、岩相互作用大多是在300～450℃和20～50MPa条件下进行的。各地区的地壳厚度不一,中地壳温度压力并不完全相同。模拟中地壳条件下水/岩相互作用实验,目的主要是研究矿物(或岩石)在300～450℃条件下反应动力学过程。已有热液矿床矿物流体包体数据表明:有一批矿床的主要矿石形成于300～500℃,低于NaCl H2O溶液临界线的条件。中地壳的流体处于由亚临界态跨越临界态,进入超临界流体太的演化过程。这种流体的性质变化会引起水/岩相互作用的反应动力学涨落和矿石大量沉淀。     

Optimal design of two-dimensional wings in ground effect using multi-objective genetic algorithm

The shape optimization of the 2-dimensional wing in ground effect (WIG) has been performed by the integration of CFD (computational fluid dynamics) and MOGA (multi-objective genetic algorithm). Because of the trade-off between the aerodynamic forces and the height stability, it is difficult to satisfy the design requirements of efficiency and stability at the same time. In this study, the lift coefficient, the lift-drag ratio and the static height stability are chosen as the objective functions to obtain the optimal wing profiles of a WIG craft. An NACA0015 airfoil is used for the baseline model; the aerodynamic characteristics of the base model are compared with that of the optimal solutions. The profile of the airfoil is constructed by four Bezier curves with fourteen control points resulting in the eighteen coordinates, which are adopted as the design variables. The optimal solutions of the multi-objective optimization are not unique but a set of the non-dominated optima: the Pareto frontiers or a Pareto set. As the results of the multi-objective optimization, the forty Pareto optima, which include high-lift, high-efficiency, and more stable airfoils on the edge of the 3-dimensional objective space, are obtained at thirty evolutions of the generation.     

海冰爬坡和堆积行为的试验研究

对于浅海区采油平台等设施常采用斜坡式人工岛形式,虽然在一定程度上起到降低海冰对平台的作用,但是海冰沿着斜坡上爬至平台并形成堆积,同样也会对平台设施造成破坏,因此有必要对海冰堆积爬坡的关键参数进行研究。通过在冰排前进方向放置混凝土实体结构物模拟海冰堆积和爬坡过程,分析了模型冰爬坡和下滑角度、最大堆积高度等关键参数以及模型冰断裂长度的统计特性及其与变形模量的关系,试验结果表明水位越高,冰排越容易发生堆积爬坡。破碎的模型冰在结构物前堆积后,形成爬坡角和下滑角。爬坡角随着堆积体的增大而增大,下滑角则逐渐减小。堆积冰高度一定时,高度不再增加,在来冰方向会形成新的堆积。这种现象为浅海区海上结构物的防冰减灾提供了新思路。     

Parameter analysis for gate metal—oxide—semiconductor structures of ion-implanted 4H silicon carbide metal—semiconductor field-effect transistors

From the theoretical analysis of the thermionic emission model of current--voltage characteristics, this paper extracts the parameters for the gate Schottky contact of two ion-implanted 4H-SiC metal--semiconductor field-effect transistors (sample A and sample B for three and four times multiple ion-implantation channel region respectively) fabricated in the experiment, including the ideality factor, the series resistance, the zero-field barrier height, the interface oxide capacitance, the interface state density distribution, the neutral level of interface states and the fixed space charge density. The methods to improve the interface of the ion-implanted Schottky contact are given at last.     

A joint distribution of significant wave height and characteristic surf parameter

The paper provides a joint distribution of significant wave height and characteristic surf parameter. The characteristic surf parameter is given by the ratio between the slope of a beach or a structure and the square root of the characteristic wave steepness in deep water defined in terms of the significant wave height and the spectral peak period. The characteristic surf parameter is used to characterize surf zone processes and is relevant for e.g. wave run-up on beaches and coastal structures. The paper presents statistical properties of the wave parameters as well as an example of results corresponding to typical field conditions.     

钦州湾潮流深槽的成因与稳定性探讨

据钦州湾2007年1—2月的实测潮流,结合径流、潮汐等资料,经水动力和港湾地形综合分析揭示:钦州湾的潮流深槽是潮流作用于葫芦形复式港湾的必然产物,是在内湾纳潮蓄能、湾颈狭道强流、颈口岛礁分流喷射冲刷而成的。通过对潮流流路和强度的分析,对潮流深槽的稳定性进行了探讨;进而通过湾颈流速-内湾纳潮关系计算,给出了潮流深槽稳定的临界条件。     

利用相关逼近法建立定位与姿态数据的同步模型

根据海道测量精密测量的需求,对姿态与定位数据融合的同步方法进行了研究。通过GPS大地高数据和升沉数据,建立了一种基于相关逼近原理的定位与姿态数据同步模型。该模型能够确定定位与姿态数据的相对延时,实现两类数据在同一时间基准下的同步。实例计算表明,定位与姿态数据的相对延迟时间已成为两类数据融合应用中必须考虑的因素。由同步模型解算后,GPS大地高数据与总升沉数据体现了更好的一致性,由此也验证了模型的有效性。     

利用TOPEX卫星高度计资料分析台湾岛周边海域巨浪和大风特征

卫星高度计实现了对全球性或区域性的海洋参量的实时监测,TOPEX卫星高度计提供了迄今为止时间序列最长、数据质量最高的全球海面风速和有效波高的同步观测资料。利用TOPEX卫星高度计资料,分析了有效波高4m以上的巨浪在台湾岛周边海域的时空分布特征,结果表明台湾岛周边海域巨浪的分布具有明显的季节特征。每年平均有效波高最大值大多数出现在夏季,春季是1a中有效波高最小的季节,而秋季和冬季是巨浪出现频率最高的季节。波高大于6m的巨浪大都出现在台湾岛东部及东北部海域,在南部海域出现较少。     

A traversing system to measure bottom boundary layer hydraulic properties

This study describes a new convenient and robust system developed to measure benthic boundary layer properties, with emphasis placed on the determination of bed shear stress and roughness height distribution within estuarine systems by using velocity measurements. This system consisted of a remotely operated motorised traverser that allowed a single ADV to collect data between 0 and 1 m above the bed. As a case study, we applied the proposed traversing system to investigate bottom boundary layer (BBL) hydraulic properties within Coombabah Creek, Queensland, Australia. Four commonly-employed techniques: (1) Log-Profile (LP); (2) Reynolds stress (RS); (3) Turbulent Kinetic Energy (TKE); and (4) Inertial Dissipation (ID) used to estimate bed shear stresses from velocity measurements were compared. Bed shear stresses estimated with these four methods agreed reasonably well; of these, the LP method was found to be most useful and reliable. Additionally, the LP method permits the calculation of roughness height, which the other three methods do not. An average value of bed shear stress of 0.46 N/m², roughness height of 4.3 mm, and drag coefficient of 0.0054 were observed within Coombabah Creek. Results are consistent with that reported for several other silty bed estuaries.     

Estimation of the wave-related ripple characteristics and induced bed shear stress

A large data set on ripples was collected and examined. A set of new formulas for the prediction of the ripple characteristics is proposed with an emphasis on the disappearance of the ripples. The ripple wavelength was observed to be proportional to the bottom wave excursion but also to be a function of the grain-related Shields parameter and wave period parameter introduced by Mogridge et al. (1994). The ripple steepness was found to be nearly constant for orbital ripples, and with a sharp decrease for suborbital ripples. Two empirical functions are added including the effects of the critical Shields parameters (inception of transport and inception of sheet flow), i.e. giving the boundaries for the ripple existence's domain. The proposed formulas yield better prediction capabilities compared to the previously published formulas, especially when ripples are washed out. The effect of the ripple characteristics on the roughness height and the calculation of the bed shear stress is also discussed. It appeared that the bed shear stress calculation is more sensitive to the empirical coefficient a_r introduced in the estimation of the ripple-induced roughness height or to the limits of existence of the ripples than the ripple characteristics themselves.