共查询到20条相似文献，搜索用时 20 毫秒
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Fuzzy logic controller (FLC) performance is greatly dependent on its inference rules. In most cases, the more rules being applied to an FLC, the accuracy of the control action is enhanced. Nevertheless, a large set of rules requires more computation time. As a result, an FLC implementation requires fast and high performance processors. This paper describes a simplified control scheme to design a fuzzy logic controller (FLC) for an underwater vehicle namely, deep submergence rescue vehicle (DSRV). The proposed method, known as the single input fuzzy logic controller (SIFLC), reduces the conventional two-input FLC (CFLC) to a single input FLC. The SIFLC offers significant reduction in rule inferences and simplifies the tuning process of control parameters. The performance of the proposed controller is validated via simulation by using the marine systems simulator (MSS) on the Matlab/Simulink® platform. During simulation, the DSRV is subjected to ocean wave disturbances. The results indicate that the SIFLC, Mamdani and Sugeno type CFLC give identical response to the same input sets. However, an SIFLC requires very minimum tuning effort and its execution time is in the orders of two magnitudes less than CFLC. 相似文献
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Prediction of wave parameters by using fuzzy logic approach 总被引：2，自引：0，他引：2
The purpose of this study is to investigate the relationship between wind speed, previous and current wave characteristics. It is expected that such a non-linear relationship includes some uncertainties. A fuzzy inference system employing fuzzy IF–THEN rules has an ability to deal with ill-defined and uncertain systems. Compared with traditional approaches, fuzzy logic is more efficient in linking the multiple inputs to a single output in a non-linear domain. In this paper, a sophisticated intelligent model, based on Takagi–Sugeno (TS) fuzzy modeling principles, was developed to predict the changes in wave characteristics such as significant wave height and zero up-crossing period due to the wind speed. Past measurements of significant wave height values and wind speed variables are used for training the adaptive model and it is then employed to predict the significant wave height amounts for future time intervals such as 1, 3, 6 and 12 h. The verification of the proposed model is achieved through the wave characteristics time series plots and various numerical error criterias. Also the model results were compared with classical Auto Regressive Moving Average with exogenous input (ARMAX) models. For the application of the proposed approach the offshore station located in the Pacific Ocean was used. 相似文献
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In this study, we propose a fuzzy approach in order to evaluate the maritime risk assessment applied to safety at sea and more particularly, the pollution prevention on the open sea. The work is based on the decision-making system, named MARISA, presented in Balmat et al. (2009). This system allowed defining a risk factor for each ship according to ship’s characteristics and weather conditions. In this novel paper, the proposed system takes into account the ship speed evolution and the ship position with respect to maritime shipping lanes is developed. To validate the method, we present an example of results with real data. 相似文献
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Jean-François Balmat Frédéric Lafont Robert Maifret Nathalie Pessel 《Ocean Engineering》2009,36(15-16):1278-1286
This paper presents a fuzzy approach for the MAritime RISk Assessment (MARISA) applied to safety at sea. The aim of this work is to define automatically an individual ship risk factor which could be used in a decision making system. To achieve this purpose, a modular and hierarchical structure using fuzzy logic has been developed. It allows us to obtain a fuzzy risk factor (FRF) composed of a static risk factor (SRF) and a dynamic risk factor (DRF). The static risk factor assessment takes into account several static data relative to the ship (age, flag, gross tonnage, number of companies, duration of detention and type). The dynamic risk factor is evaluated by considering the meteorological conditions (sea state, wind speed and visibility) and the moment of the day. Moreover, the MARISA graphic interface developed with the Labview software is presented. This interface allows several simulations to be carried out to validate the fuzzy method proposed. Simulation results are presented. 相似文献
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A fuzzy logic controller for ship path control in restricted waters is developed and evaluated. The controller uses inputs of heading, yaw rate, and lateral offset from the nominal track to produce a commanded rudder angle. Input variable fuzzification, fuzzy associative memory rules, and output set defuzzification are described. Two maneuvering situations are evaluated: track keeping along a specified path where linearized regulator control is valid; and larger maneuvers onto a specified path where nonlinear modeling and control are required. For the track keeping assessment, the controller is benchmarked against a conventional linear quadratic Gaussian (LQG) optimal controller and Kalman filter control system. The Kalman filter is used to produce the input state variable estimates for the fuzzy controller as well. An initial startup transient and regulator control performance with an external hydrodynamic disturbance are evaluated using linear model simulations of a crude oil tanker. A fully nonlinear maneuvering model for a smaller product tanker is used to assess the larger maneuvers 相似文献
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Real-time wave forecasting using genetic programming 总被引：4，自引：0，他引：4
The forecasting of ocean waves on real-time or online basis is necessary while carrying out any operational activity in the ocean. In order to obtain forecasts that are station-specific a time-series-based approach like stochastic modeling or artificial neural network was attempted by some investigators in the past. This paper presents an application of a relatively new soft computing tool called genetic programming for this purpose. Genetic programming is an extension of genetic algorithm and it is suited to explore dependency between input and output data sets. The wave rider buoy measurements available at two locations in the Gulf of Mexico are analyzed. The forecasts of significant wave heights are made over lead times of 3, 6, 12 and 24 h. The sample size belonged to a period of 15 years and it included an extensive testing period of 5 years. The forecasts made by the approach of genetic programming indicated that it can be regarded as a promising tool for future applications to ocean predictions. 相似文献
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Study on the uncertainty of the available time under ship fire based on Monte Carlo sampling method 总被引：1，自引：0，他引：1
Available safety egress time under ship fire(SFAT) is critical to ship fire safety assessment,design and emergency rescue.Although it is available to determine SFAT by using fire models such as the two-zone fire model CFAST and the field model FDS,none of these models can address the uncertainties involved in the input parameters.To solve this problem,current study presents a framework of uncertainty analysis for SFAT.Firstly,a deterministic model estimating SFAT is built.The uncertainties of the input parameters are regarded as random variables with the given probability distribution functions.Subsequently,the deterministic SFAT model is employed to couple with a Monte Carlo sampling method to investigate the uncertainties of the SFAT.The Spearman’s rank-order correlation coefficient(SRCC) is used to examine the sensitivity of each input uncertainty parameter on SFAT.To illustrate the proposed approach in detail,a case study is performed.Based on the proposed approach,probability density function and cumulative density function of SFAT are obtained.Furthermore,sensitivity analysis with regard to SFAT is also conducted.The results give a high-negative correlation of SFAT and the fire growth coefficient whereas the effect of other parameters is so weak that they can be neglected. 相似文献
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We propose a basic ship design knowledge-model for information storage and retrieval using a knowledge-based engineering (KBE) system and develop a semantic inquiry function that allows users to use the retrieved information immediately. Our aim is to merge the repetitive access and calculating tasks and data such as the principal dimensions required during the basic ship design process into a single database, so that this information remains available for future construction projects. However, the concept of linking a design knowledge base and inference engine requires the combining of ship design information with the KBE system. This research enhances the flexibility, extension, and operation of the inference mechanism of the KBE design methodology through the establishment of a user interface, knowledge base, and inference engine. The design information is managed a document-based approach, which requires the conversion of the original documents into the XML (eXtensible Markup Language) format, and compiles rules for the basic design process. This system uses the KBE method attempts to reduce the double workload of design and modeling at the commencement of a new project with the document-generating integration work. 相似文献
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海洋平台磁流变阻尼器控制技术研究 总被引：3，自引：0，他引：3
为了更有效地减小海洋平台动力响应,采用基于模糊控制算法的磁流变阻尼器对海洋平台的振动进行控制.以海洋平台位移响应误差和误差变化为输入变量,以最优控制力为输出变量,优化设计出模糊控制器.考虑实际磁流变阻尼器输出控制力上限存在限制,采用半主动控制算法计算接近于最优控制力的半主动控制力.以一固定式海洋平台为算例研究磁流变阻尼器的振动控制效果及其模糊性,仿真结果表明模糊磁流变控制器对于平台的振动可以实现非常有效的控制,且控制效果对结构阻尼和环境的不确定性具有较好的模糊性. 相似文献
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Fuzzy Optimum Model of Semi-Structural Decision for Lectotype Optimization of Offshore Platforms 总被引：8，自引：0，他引：8
In the process of concept design of offshore platforms, it is necessary to select the best from feasible alternatives through comparison and filter. The criterion set, used to evaluate and select the satisfying alternative, consists of many qualitative and quantitative factors. Therefore, the selection is a problem of multicriteria and semi- structural decision- making. Different from traditional methods in semi- structural decision- making, a new framework and methodology is presented in this paper for evaluation of offshore platform alternatives. First, the criterion set is established for the evaluation of alternatives. Next, the approach is studied to construct the relative membership degree matrix, in which both qualitative and quantitative factors are consistent with the uniform calculating standard. And then a new weight-assessing method is developed for calculation of the weights based on the relative membership degree matrix. Finally, a multi-hierarchy fuzzy optimum model is adopted to select t 相似文献
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Nusret Demir Bülent Bayram Dursun Zafer Şeker Selen Oy Abdülkadir İnce Salih Bozkurt 《Marine Geodesy》2019,42(2):166-185
Noise and an abnormal distributed-image histogram is the main challenge of using SAR data. From this point of view, this study’s authors motivated the non-use of user-defined input parameters. To achieve this purpose, a fuzzy approach was proposed to extract shoreline from SENTINEL-1A data. The parameters in the processing of the SENTINEL-1A image were generated automatically with LIDAR-intensity-derived object-based segmentation results. The LIDAR-intensity image was segmented with the Mean-shift method. The corresponding result was used to estimate the input parameters for fuzzy clustering of the SENTINEL-1A image. Fuzzy segmentation was proposed, due to the expected large number of values regarding water and land classes except for the pixels along the shoreline. The memberships for land and water classes were separately computed. In the proposed approach, the results from LIDAR and SENTINEL-1A dataset are promising, with differences below 1 pixel (10?m) by evaluation with the used reference vector data. 相似文献
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It is difficult to compute far-field waves in a relative large area by using one wave generation model when a large calculation domain is needed because of large dimensions of the waterway and long distance of the required computing points. Variation of waterway bathymetry and nonlinearity in the far field cannot be included in a ship fixed process either. A coupled method combining a wave generation model and wave propagation model is then used in this paper to simulate the wash waves generated by the passing ship. A NURBS-based higher order panel method is adopted as the stationary wave generation model; a wave spectrum method and Boussinesq-type equation wave model are used as the wave propagation model for the constant water depth condition and variable water depth condition, respectively. The waves calculated by the NURBS-based higher order panel method in the near field are used as the input for the wave spectrum method and the Boussinesq-type equation wave model to obtain the far-field waves. With this approach it is possible to simulate the ship wash waves including the effects of water depth and waterway bathymetry. Parts of the calculated results are validated experimentally, and the agreement is demonstrated. The effects of ship wash waves on the moored ship are discussed by using a diffraction theory method. The results indicate that the prediction of the ship induced waves by coupling models is feasible. 相似文献
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1 .IntroductionAshiptravelingatseaundergoesundesirablewave inducedmotions ,namely ,surge ,sway ,heav ing ,rolling ,pitchingandyaw .Thesemotionsoftencauseproblemstothecrew ,theonboardequip mentand ,intheworstcase ,thesafetyofthevessel.Tominimizethewave inducedshipmotions ,controlsystemsmaybeapplied .Theaccuratemodelingofshipmotionsisthereforeveryimportantforshipdesignanddesignofmotioncontrolsystems .Manyresearchershavedevelopedshipmotionpredictionmethodsbasedonthepotentialflowtheo ries (Dong ,… 相似文献
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混凝土强度评定的准确性对结构物的安全性评价具有很大的影响。为了充分利用钻芯法和回弹法这2种常用混凝土测强方法的特点,建立自适应模糊神经推理系统模型来综合评定结构的混凝土强度。将回弹值的常用对数和碳化深度值作为模型的输入,钻芯值的常用对数作为模型的输出。模型参数采用混合算法确定。其中,条件参数采用梯度下降法来调整;结论参数采用最小二乘法来调整。该模型可以有效地映射出训练数据之间复杂的非线性关系。通过对已有的钻芯、回弹试验数据的对比计算,自适应模糊神经推理系统方法的强度预测精度高于常规的回归方法。 相似文献