Approximate Stream Function wavemaker theory for highly non-linear waves in wave flumes

An approximate Stream Function wavemaker theory for highly non-linear regular waves in flumes is presented. This theory is based on an ad hoc unified wave-generation method that combines linear fully dispersive wavemaker theory and wave generation for non-linear shallow water waves. This is done by applying a dispersion correction to the paddle position obtained for non-linear long waves. The method is validated by a number of wave flume experiments while comparing with results of linear wavemaker theory, second-order wavemaker theory and Cnoidal wavemaker theory within its range of application.     

Wave modelling - The state of the art

This paper is the product of the wave modelling community and it tries to make a picture of the present situation in this branch of science, exploring the previous and the most recent results and looking ahead towards the solution of the problems we presently face. Both theory and applications are considered.The many faces of the subject imply separate discussions. This is reflected into the single sections, seven of them, each dealing with a specific topic, the whole providing a broad and solid overview of the present state of the art. After an introduction framing the problem and the approach we followed, we deal in sequence with the following subjects: (Section) 2, generation by wind; 3, nonlinear interactions in deep water; 4, white-capping dissipation; 5, nonlinear interactions in shallow water; 6, dissipation at the sea bottom; 7, wave propagation; 8, numerics. The two final sections, 9 and 10, summarize the present situation from a general point of view and try to look at the future developments.     

Transient response of harbours to long waves under resonance conditions

This paper presents the results of a study aimed at quantifying the time–response of harbour basins to long waves under resonance conditions. On the basis of numerical simulations reproducing long waves in the yacht harbour of Rome (Ostia, Italy), it shows that the results valid for periodic forcing waves, acting for an infinitely long time, as those provided by models based on elliptic equations like the Helmoltz and the mild-slope equations, can be misleading with respect to the more realistic ones that can be obtained using time-varying wave equations. Taking advantage of the similarity between the processes studied here and a simple one-dimensional resonator, a method is also proposed to roughly estimate a time–response parameter of each mode of the harbour, using results from steady-state numerical model results, commonly applied for studying harbour resonance in engineering practice. On the basis of further numerical simulations, aimed at reproducing schematic harbour layouts, the effect on resonance of the position of the entrance and of an outer harbour is studied. The results indicate that the effects of design solutions to reduce resonance, by placing the entrance at the middle of the harbour, or using the outer harbour as a resonator, can be correctly evaluated only when considering the time needed for the oscillations to fully develop.     

A note on nearshore wave features: Implications for wave generation

This paper analyses 10 years of wave data from the Mediterranean Spanish (Catalan) coast considering the mean wave climate and storm events from the standpoint of wind-wave momentum transfer and wave prediction. The data, registered by a buoy at about 12 km from the coastline, revealed two main groups of wave storms, with NW and E directions. NW storms correspond to a fetch-limited situation since the intense wind blows from land. Low-pressure centres located over the Mediterranean Sea produce easterly storms. Near the coast the eastern winds from the sea are replaced by NW winds coming from meteorological patterns over northern Spain and south-western France. Wave storms are classified and studied to obtain their main features (including spectral width, wave length, wave age and bimodality) and discussed in terms of wind-wave momentum transfer for operational wave predictions. Observations show a complex coastal wave climate. Fetch-limited storms presented smaller spectral widths while varying wind situations presented larger widths due to the presence of bimodal spectra. These wave features are highly relevant for wind–ocean momentum transfer and, thus, for current and wave predictions. The spectral width proved to be a good indicator of sea complexity and is thus applicable for improved wind drag estimations. A new drag coefficient formulation is proposed, based on existing wind dependent drag expressions, but including also spectral wave properties (a spectral width parameter) that highlights the characteristics of wind-wave generation under pre-existing swell. Such a formulation, once properly validated with field observations, is expected to improve wind-wave predictions.     

南堡凹陷古近系层序地层格架中烃源岩分布与生烃特征研究

南堡凹陷油气资源丰富,古近系主要分布有沙三段、沙一段和东三段三套有效烃源岩。在层序地层学研究的基础上,应用有机地球化学、有机岩石学和沉积有机相等研究手段和方法对东三段、沙一段和沙三段不同层序和同一层序不同体系域中烃源岩特征进行综合研究。结果表明,南堡地区烃源岩非均质性特征明显,烃源岩生烃的层位主要分布于SQ9、SQ5~SQ8、SQ2和SQ1的湖扩展体系域和早期高位体系域,SQ2为优质烃源岩段。造成这种非均质性的主要原因是不同体系域的沉积特征,这影响着烃源岩有机质类型和保存条件。     

合肥盆地烃源岩有机质热演化历史分析

利用镜质体反射率资料及其定量恢复的合肥盆地的古地温结合伊利石结晶度测定系统研究了盆地石炭-二叠系以来的热演化史,在此基础上分析了石炭-二叠系、下侏罗系、中上侏罗系、白垩系、古近系的烃源岩有机质的热演化程度及热演化史,结果表明合肥盆地C-P系呈现为高成熟阶段,并在下侏罗统沉积之后开始进入生油门限,在上侏罗统沉积后地温曾达245℃,而在白垩纪中期(朱巷组沉积后)最大古地温度达到过305℃指示进入了过成熟阶段。下侏罗统防虎山组Ro值和伊利石结晶度也显示了较高的热演化程度,在中侏罗统沉积后开始进入生油门限,在早白垩世朱巷组沉积后达到了最高的热演化程度,最大古地温达260℃。中-上侏罗统随着下白垩统朱巷组的沉积而进入生油门限,在下白垩统沉积之后达到了最大的古地温度,分别为225℃、230℃,指示开始进入过成熟阶段,朱巷组最大埋藏温度出现在早白垩世末,达到了110～120℃,指示进入了成熟期。在上覆古近系沉积后曾达到最大古地温(110～160℃),显示进入了成熟阶段。古近系定远组未进入成熟阶段,最大古地温出现在定远组沉积之后,但小于50℃。     

The geochemical characteristics and oil-source rock correlation of oilshow from the Majiashan profile,Chaoxian County,South of Anhui Province

In the future time the exploration of marine oil and gas will be one of the significant domains in China. In this paper the biomarker assemblage characteristics of oilshow in the Nanlinghu Formation of the Majiashan profile, which is located in Chaoxian County, south of Anhui Province, are described in the light of gas chromatography/mass spectrometric （GCMS） analysis on the qualitative and quantitative basis. Based on the investigation of the biomarker assemblage characteristics of possible source rocks developed in the area studied, a conclusion is drawn that the oilshow was generated from the Nanlinghu Formation source rocks （abbreviated as Tin）, instead of the Qixia Formation source rocks （abbreviated as P1q）. It is pointed out that the Tin is of strong potential for future oil exploration, and therefore much attention should be paid to it.     

地测空间信息系统功能在地质勘探报告中的应用简介

地测空间信息系统(CGIS)在地质勘探部门、矿山地测部门实现了自动化处理地测图形,即钻孔柱状图、煤层结构综合柱状、煤岩层对比图、封孔结构图、地质实测剖面图、地质剖面图及各类等值线图等图件,并可自动形成各类报告、生产报表,改变以往手工绘制图件,可节省大量的人力、物力、财力。     

旅游研究中的代际理论及其应用述评

旅游消费行为和偏好等旅游市场研究是旅游理论发展与操作实践的核心内容,而代际研究能很好地解释游客的旅游消费行为。文章通过对代际理论发展及其在旅游研究中应用的相关文献进行详细梳理和分析,从代际理论内涵、代际划分和代际理论在旅游研究中的应用3方面综述了国内外代际理论在旅游研究中应用的最新研究进展。发现国外从代际理论视角研究游客旅游消费行为,既注重代际之间差异的横向对比,又重视同个代不同时段的纵向分析,还关注年龄、代群、周期性外部事件等对游客旅游活动的影响,其研究广度和深度不断拓展增强,科学的实证分析也为旅游开发管理提供了有益的理论指导。而国内相关的研究还未广泛展开,既无法进行深入、系统的理论分析,又缺乏严谨、科学的实证探索。因此,当前中国在应用代际理论研究游客旅游消费行为时,应明确中国代际划分、辨析旅游消费行为,开展代际理论与区域差异耦合研究,拓展代际理论在旅游研究中的时空尺度。     

国土审计空间辅助系统的实现

针对传统国土审计方法无法快速发现土地违法利用的问题,该文建立了基于审计方法模型的国土审计空间辅助系统。该系统由数据展示、数据交换、影像自动识别提取、审计模型分析等模块组成;利用该系统对耕地保护、土地开发、违法建筑等审计方向建立模型并分析应用,并对遥感影像分类识别算法与动态生成图层应用关键技术进行探讨。该系统已应用在浙江省的市县国土专项审计、省土地出让金收支审计项目中,完成了高准确度的基本农田范围内疑似违法用地提取与按需生成空间范围图层,为国土审计工作提供了从二维展示到空间分析提取等多样管理与决策手段,提升了国土审计监督能力。