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971.
The subject of measuring the performance of registries has been a topic of policy discussions in recent years at the regional level due to the recasting of the European Union (EU) port state control (PSC) directive which introduces incentives for flags which perform better. Since the current method used in the EU region entails some shortcomings, it has therefore been the subject of substantial scrutiny. Furthermore, the International Maritime Organization (IMO) developed a set of performance indicators which however lacks the ability to measure compliance as set out in one of its strategic directions towards fostering global compliance. This article develops a methodology to measure flag state performance which can be applied on the regional or global level and to other areas of legislative interest (e.g. recognized organizations, Document of Compliance Companies). The proposed methodology overcomes some of the shortcomings of the present method and presents a more refined, less biased approach of measuring performance. To demonstrate its usefulness, it is applied to a sample of 207,821 observations for a 3-year time frame and compared to the current method. 相似文献
972.
Study of A Geo-Acoustic Model of Gas-Bearing Sediment and Its Application in Sediment with Low Acoustic Veloctiy 总被引:2,自引:0,他引:2
A new geo-acoustic model for gas-bearing sediment is proposed based on the work of Dvorkin and Prasad, and Biot theory. Only five geophysical parameters: sediment mineral composition, free gas saturation, tortuosity (also known as the structure factor), permeability, and porosity, are considered in the model. A benefit of this model is that we need only five parameters instead of ten parameters in the Biot's formulas for acoustic velocity and attenuation calculation. Here the model is demonstrated with the in-situ experimental data collected from the Hangzhou Bay, China. The results of this study suggest that free gas content in sediment is the most critical condition resulting in a low acoustic velocity (compressional wave). The respective contributions of the other four parameters in the model are also discussed. 相似文献
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975.
Albert K. Chong Peter Milburn Richard Newsham-West Marieketer Voert 《The Photogrammetric Record》2009,24(127):264-279
Close range photogrammetry has been recognised as an essential tool for the capture of high-accuracy spatial data for medical applications, in particular work involving dynamic human body parts such as limbs. Offline and online photogrammetric systems are readily available for a number of common applications. However, off-the-shelf systems are not always appropriate because of project site conditions. To achieve high measurement accuracy in a field environment, a modified field camera calibration technique was introduced. The technique is particularly important where each camera is limited to one captured image during calibration, as the camera and the calibration testfield are in fixed positions. In this paper a custom-built imaging system designed for the study of the human spine in an outdoor environment is introduced. The discussion addresses: (1) imaging system design; (2) modified field calibration techniques; and (3) a case study on human spines. Two field camera calibration techniques were evaluated, both of which improved the accuracy of the prototype system, the use of a detachable target board offering the best results. This modified camera calibration procedure has improved the 3D measurement accuracy from 1·25 ± 0·3 mm to 0·43 ± 0·1 mm. The improvement is at a level achievable in the laboratory. The technique is considered to provide accurate and reliable anthropometric landmark measurement at low cost. This was evaluated in a clinical setting where diurnal changes in spine length and contour were measured in a cohort of 30 university students. The capability of the technique to measure sagittal and frontal angular changes provides a novel way of examining changes in spine shape. 相似文献
976.
J. Feltens 《Journal of Geodesy》2009,83(2):129-137
The vector-based algorithm to transform Cartesian (X, Y, Z ) into geodetic coordinates (, λ, h) presented by Feltens (J Geod, 2007, doi:) has been extended for triaxial ellipsoids. The extended algorithm is again based on simple formulae and has successfully
been tested for the Earth and other celestial bodies and for a wide range of positive and negative ellipsoidal heights. 相似文献
977.
In collocation applications, the prior covariance matrices or weight matrices between the signals and the observations should
be consistent to their uncertainties; otherwise, the solution of collocation will be distorted. To balance the covariance
matrices of the signals and the observations, a new adaptive collocation estimator is thus derived in which the corresponding
adaptive factor is constructed by the ratio of the variance components of the signals and the observations. A maximum likelihood
estimator of the variance components is thus derived based on the collocation functional model and stochastic model. A simplified
Helmert type estimator of the variance components for the collocation is also introduced and compared to the derived maximum
likelihood type estimator. Reasonable and consistent covariance matrices of the signals and the observations are arrived through
the adjustment of the adaptive factor. The new adaptive collocation with related adaptive factor constructed by the derived
variance components is applied in a transformation between the geodetic height derived by GPS and orthometric height. It is
shown that the adaptive collocation is not only simple in calculation but also effective in balancing the contribution of
observations and the signals in the collocation model. 相似文献
978.
介绍了广州市轨道交通线路竣工验收测量的技术方案,论述了验收测量的相关技术,提供了轨道交通线路竣工验收测量的借鉴。 相似文献
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980.
对GPS—RTK技术应用于城市1:500数字地形测量实验方法进行了研究,探索GPS-RTK技术辅以全站仪进行图根控制测量、数字地形测量的数据采集模式,改变传统的等级导线控制测量下进行图根测量与测图的经典模式。通过GPS—RTK技术阶段性测量数据检测,控制成果的可靠性,形成满足数字地形图测图需要的作业方法。 相似文献