Fisheries regulation: A survey of the literature on uncertainty,compliance behavior and asymmetric information

Economists normally claim that a stock externality arises within fisheries because each individual fisherman does not take the effect on stock size into account when making harvest decisions. Due to the stock externality, it is commonly argued that fisheries regulation is necessary, but regulatory decisions are complicated by a tremendous amount of uncertainty and asymmetric information. This paper provides an overview of selected parts of the literature on the regulation of fisheries under uncertainty and asymmetric information, and possible areas for future research are identified. Specifically, three main topics are covered. First, the issue of choosing regulatory instruments under uncertainty is discussed. Second, compliance and enforcement problems caused by fisheries regulation are investigated. Third, alternatives to a traditional enforcement policy are presented.     

An experimental study on water entry of asymmetric wedges

The aim of the paper is to provide an experimental reference for investigation of asymmetric water entry of wedges. Parameters of the study include initial deadrise angle, inclination angle and impact speed. Initial deadrise angles of the wedges were 20° and 30° with inclination angles ranging from 0° to 15° in 5° increments. Wedges were freely fallen from three different heights. Time histories of impact pressure and body acceleration were recorded. Sampling rate of measurements were set to 25 KHz. Main configuration of each test including mass of the wedge and water level were kept unchanged during all experiments. Additionally, several calibration tests were conducted to assess the repeatability and accuracy of the recorded data. The experimental results are compared with different entry theories and other available experiments. The comparison shows a reasonable agreement and indicates that the inclination angle can dramatically affect the impact pressure experienced by the wedges. Finally, the results show that the traditional asymmetric theories are not appropriate for all inclination angles.     

Uncertainty in the analysis of speed and powering trials

Full-scale speed trials of a ship have been questioned for the uncertainty of speed and power measurements especially when the sea conditions differ from the ideal calm water conditions. Such uncertainty has been investigated by utilizing ITTC standard speed/powering trial analysis procedure through Monte Carlo simulations. A case study was conducted for a set of sea trials with 12 sister ships for which sea trial data were available for a range of displacement, water depth, water temperature, wind speed and wave height values. Precision errors were observed as the most influential error source for the whole speed range, even though their effects were more substantial at low speeds. Beaufort scale was observed as the most important elementary error source indicating the need for the best weather conditions for the most reliable sea trail predictions.     

Uncertainty in marine weather routing

Weather routing methods are essential for planning routes for commercial shipping and recreational craft. This paper provides a methodology for quantifying the significance of numerical error and performance model uncertainty on the predictions returned from a weather routing algorithm. The numerical error of the routing algorithm is estimated by solving the optimum path over different discretizations of the environment. The uncertainty associated with the performance model is linearly varied in order to quantify its significance. The methodology is applied to a sailing craft routing problem: the prediction of the voyaging time for an ethnographic voyaging canoe across long distance voyages in Polynesia. We find that the average numerical error is an order of magnitude smaller than the performance model uncertainty. These results illustrate the significance of considering the influence of numerical error and performance uncertainty when performing a weather routing study.     

ARABESQUE: An overview

This special issue reports the results of ARABESQUE, an UK-led, international programme of upper-ocean biogeochemistry in the Arabian Sea region, conducted during two contrasting seasons. The seasons studied were the waning of the southwest monsoon in August/September and the intermonsoon-northeast monsoon transition in November/December 1994. Biogeochemical studies were carried out along three transects in the Gulf of Oman and the Arabian Sea. The main ARABESQUE transect, 1590 km in length, lay orthogonal to the southern Oman coast and spanned a range of conditions that encompassed coastal seasonal upwelling through to oceanic aseasonal oligotrophy of the central Arabian Sea. Surface mixed-layer hydrography, PAR, wind speed and direction fields, and research results obtained during the two seasonal studies are summarised in this paper, which also serves as an introductory overview to ARABESQUE.     

实验室盐度计校准结果的不确定度分析

文中分析了实验室盐度计校准不确定度来源项,按不确定度的评定方法,以实例形式分析评定了校准结果的不确定度。     

Expert systems: An overview

"Expert systems" is a phrase that is widely used in today's literature to describe a technology that provides for emulating human reasoning processes in a computer. This paper attempts to clarify what the phrase expert systems means and briefly describes the underlying technology that is used to implement expert systems.     

Cheniers in China: An overview

In various regions along the east and southeast coast of China and on the outer shelf of the East China Sea, series of cheniers have been found and studied. Their geomorphological and sedimentological features have been described and the main conditions for their formation established.

The development of cheniers in China can be divided into three periods: 24,000-15,000 yrs B.P., 7000-5000 yrs B.P. and 5000 yrs B.P. onwards. These periods have been based on ¹⁴C datings of 80 shell samples. The chenier groups of the three periods are distributed throughout various geomorphological locations.

Using the geomorphological locations of the cheniers in combination with their age of formation, the palaeopositions of the Chinese coastline in the various periods since 24,000 yrs B.P. are described. The history of the position of the east coast of China, including the features attesting to sealevel changes during this era, is briefly discussed.     

Uncertainty in predictions of oil spill trajectories in open sea

A method is introduced to calculate and to account for the uncertainties in the predictions of oil spill trajectories using a classic oil spill model. The method considers the output of the oil spill model as a function of random variables, which are the input parameters, and calculates the standard deviation of the output results which gives a measure of the uncertainty of the model given the uncertainties of the input parameters.Instead of a single trajectory that is calculated by the oil spill model using the mean values of the parameters, a band of trajectories can be defined when various simulations are done taking into account the uncertainties of the input parameters. This band of trajectories defines envelopes of the trajectories that are likely to be followed by the spill given the uncertainties of the input.The method is applied to an oil spill that occurred in open sea near Madeira Islands, in the Atlantic Ocean, in December 1989. The simulations allow the understanding of how a change in the wind direction drove the spill towards the Islands.The envelope of likely trajectories that is obtained with the uncertainty modelling shows a band of trajectories that is in better agreement with the observations than the single trajectory simulated by the oil spill model, based on mean parameters.     

Uncertainty of full-scale manoeuvring trial results estimated using a simulation model

This paper describes how to estimate the uncertainty of manoeuvring sea trial results without performing repeated tests using only a simulation model. The approach is based on the Monte Carlo method of uncertainty propagation. Moreover, the global sensitivity analysis procedure based on variance decomposition is described. As an example, the method is applied to estimate the uncertainty of 10°/10° zigzag overshoot angles and a 20° turning circle advance and tactical diameter for a small research vessel. The estimated uncertainty is compared with corresponding experimental uncertainty assessed from repeated tests. The method can be useful for validation studies and other studies that involve the uncertainty of sea trial results.     

海洋沉积物中铜含量测量不确定度评定 ——电热板加热消解法与微波消解法的比对

电热板加热消解法和微波消解法是目前海洋沉积物样品消解的常用方法。为了比较这两种处理方法对检测结果准确性的影响程度,文章依据《测量不确定度的评定与表示》技术规定中的相关要求对海洋沉积物中铜含量测定过程中采取的两种消解方法进行了不确定度评定与对比,建立了模型,并对各不确定度分量进行分析和量化,计算出两种消解方法测量沉积物中铜含量的相对合成不确定度分别为0.06721和0.04033,扩展不确定度分别为4.0mg/kg和2.4mg/kg。通过比较两种消解方法对测定结果不确定度的贡献,发现微波消解法明显优于电热板加热法。     

海洋专题制图标准的发展与展望

海洋专题制图标准是规范海洋专题图制作、建立读图者一致认知, 以及实现海洋信息共享的基础。随着我国海洋科 学调查的逐步深入及大量制图成果的涌现, 制图标准化工作越来越受到重视。本文从定义与描述 、获取与处理 、检测与测 试 、成果与服务等 4 个方面梳理了国内外海洋制图标准的发展状况。结果表明： (1) 海洋专题地图的标准化尚待提高, 尤 其是与陆地基本比例尺地形图 、地质图 、航海图标准化相比, 发展较为缓慢; (2) 908 专项及全球变化与海气相互作用专 项在海洋制图标准方面的大力建设, 使得海洋专题要素分类 、表示方法 、图件类型和图面整饰等趋于成熟和一致; (3) 当 前海洋专题制图标准多以定义描述类的图式图例为主, 缺乏处理与分析、表达与管理、检查与评价、输出与共享等全链条的 标准支撑。今后, 除海洋调查、信息化之外海洋制图应加大其他领域如海洋生态、规划、灾害等海洋制图标准的编制, 注重 多要素、多维度、多时序海洋现象和规律的制图表达, 深化地图要素设计认知等方面的研究。     

Effect of bed roughness on turbulent boundary layer and net sediment transport under asymmetric waves

This paper presents an investigation of the roughness effects in the turbulent boundary layer for asymmetric waves by using the baseline (BSL) k–ω model. This model is validated by a set of the experimental data with different wave non-linearity index, N_i (namely, N_i = 0.67, N_i = 0.60 and N_i = 0.58). It is further used to simulate asymmetric wave velocity flows with several values of the roughness parameter (a_m/k_s) which increase gradually, namely from a_m/k_s = 35 to a_m/k_s = 963. The effect of the roughness tends to increase the turbulent kinetic energy and to decrease the mean velocity distribution in the inner boundary layer, whereas in the outer boundary layer, the roughness alters the turbulent kinetic energy and the mean velocity distribution is relatively unaffected. A new simple calculation method of bottom shear stress based on incorporating velocity and acceleration terms is proposed and applied into the calculation of the rate of bed-load transport induced by asymmetric waves. And further, the effect of bed roughness on the bottom shear stress and bed-load sediment transport under asymmetric waves is examined with the turbulent model, the newly proposed method, and the existing calculation method. It is found that the higher roughness elements increase the magnitude of bottom shear stress along a wave cycle and consequently, the potential net sediment transport rate. Moreover, the wave non-linearity also shows a big impact on the bottom shear stress and the net sediment transport.     

Quantitative estimation of petroleum prospect outcome probabilities: an overview of procedures

Estimation of prospect outcome probabilities in numerical form should be a central objective for petroleum geologists. Most numerical estimates of outcome probabilities represent subjective guesses. While the effectiveness of subjective procedures is difficult to gauge, several postmortem analyses suggest that subjective procedures are ineffective. Objective procedures for estimating outcome probabilities should yield much improved estimates. Objective procedures require that geological, geophysical and production data be organized so that geological and geophysical characteristics of prospects interpreted before they were drilled can be compared systematically with outcomes of prospects after they have been drilled. An example application that involves well data and an example application that involves seismic data demonstrate that objective procedures are simple in principle, but require organization of information in a form suitable for computation of frequencies, on which objective estimates of probabilities can be based.     

Liner shipping and information exchange—a European perspective

The European Commission (EC) is currently reviewing Council Regulation 4056/86, which includes the proposal by the European Liner Affairs Association (ELAA) to put in place a regulatory instrument for an information exchange system. The White Paper of the EC, issued in 2004, which provides a comprehensive discussion of the key issues including the ELAA proposal, is examined. The implications of the removal of Regulation 4056/86 and the application of this information exchange instrument in its place are studied. Arising from the protection afforded by antitrust immunity for nearly 100 years owners appear to have developed a fear of the unknown regarding an unregulated environment.     

An overview of SAX99: acoustic measurements

A high-frequency acoustic experiment was performed at a site 2 km from shore on the Florida Panhandle near Fort Walton Beach in water of 18-19 m depth. The goal of the experiment was, for high-frequency acoustic fields (mostly In the 10-300-kHz range), to quantify backscattering from the seafloor sediment, penetration into the sediment, and propagation within the sediment. In addition, spheres and other objects were used to gather data on acoustic detection of buried objects. The high-frequency acoustic interaction with the medium sand sediment was investigated at grazing angles both above and below the critical angle of about 30°. Detailed characterizations of the upper seafloor physical properties were made to aid in quantifying the acoustic interaction with the seafloor. Biological processes within the seabed and the water column were also investigated with the goal of understanding their impact on acoustic properties. This paper summarizes the topics that motivated the experiment, outlines the scope of the measurements done, and presents preliminary acoustics results     

Global trade in fish and fishery products: An overview

Global trade in fishery products plays a significant role in shaping the harvesting and use of fish, and therefore will be an important part of a transition to sustainable fisheries. This article provides an overview of global trade flows in fish and fishery products as well as future trends affecting the sector. It then moves on to review trade policy measures applied in major producing and importing countries, including tariff, non-tariff measures, and fisheries subsidies. It ends with an overview of recent developments in international frameworks governing trade in fish and fishery products at the global, regional and national levels.     

The link between tectonics and sedimentation in asymmetric extensional basins: Inferences from the study of the Sarajevo-Zenica Basin

The coupled tectonic and depositional history of extensional basins is usually described in terms of stratigraphic sequences linked with the activity of normal faults. This depositional-kinematic interplay is less understood in basins bounded by major extensional detachments or normal fault systems associated with significant exhumation of footwalls. Of particular interest is the link between tectonics and sedimentation during the migration of normal faulting in time and space across the basin. One area where such coupled depositional-kinematic history can be optimally studied is the Late Oligocene - Miocene Sarajevo-Zenica Basin, located in the Dinarides Mountains of Bosnia and Herzegovina. This intra-montane basin recorded Oligocene – Pliocene sedimentation in an endemic and isolated lake environment. We use field kinematic and sedimentological mapping in outcrops correlated with existing local and regional studies to derive a high-resolution evolutionary model of the basin. The novel results demonstrate a close correlation between moments of normal faulting and high-order sedimentological cycles, while the overall extensional basin was filled by a largely uni-directional sediment supply from the neighbouring mountain chain. The migration in time and space of listric NE-dipping normal faults was associated with a gradual shift of the sedimentological environment. Transgressive-regressive cycles reflect sequential displacements on normal faults and their footwall exhumation, defining a new sedimentological model for such basins. This Early - Middle Miocene extension affected the central part of the Dinarides and was associated with the larger opening of the neighbouring Pannonian Basin. The extension was preceded and followed by two phases of contraction. The Oligocene - Early Miocene thrusting took place during the final stages of the Dinarides collision, while the post-Middle Miocene contraction is correlated with the regional indentation of the Adriatic continental unit. This latter phase inverted the extensional basin by reactivating the inherited basal listric detachment.     

Experimentally-based investigation of effects of wave interference on the wave resistance of asymmetric di-hulls

Significant reduction of steady-state resistance of a di-hull system with certain hull configurations (relative stagger and separation between the hulls) occurs because of interference effects between the two sets of ship-generated waves. The far-field wave interference and the resulting wave-resistance reduction of an asymmetric di-hull system, consisting of two distinct Series 60 hull models with various hull configurations are studied. The initial search for optimal configurations of the maximum prospective resistance reduction is conducted by an existing di-hull thin-ship computation. These theoretical results are then compared to the ones acquired by towing-tank measurements and those given by a semi-experimental approach. The latter approach obtains the wave resistance by combining experimental “wave-cut” data and analytical expressions developed for such a di-hull system. Experimental uncertainties are briefly discussed. Results of this study show that a considerable amount of wave-resistance reduction is indeed possible for the investigated hull configurations. However, beyond the far-field interference of the waves, near-field interactions of the two hulls are found to have non-negligible influence on the total resistance performance of the di-hull system.