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1.
The potential of ozone for disinfection of ships’ ballast water was investigated using Bacillus subtilis spores as an indicator. The effects of pH, presence of iron, and bacterial strain on disinfection efficacy in seawater, under simulated ballast conditions, were investigated. Ozone dosages of 9 mg/L (pH 7) and 14 mg/L (pH 8.2) and 24 h contact achieved a 4-log inactivation with the various oxidant residuals formed. Iron surface at a ratio to water of 9 m2/m3 impaired the oxidant residuals and the disinfection of spores. Different strains of B. subtilis resulted in different CT values. Ozone does not seem to be a good choice for the control of spore-forming organisms in ballast water, but may be suitable for the control of other species. 相似文献
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深浅水中KVLCC船体横荡运动水动力数值计算 总被引:1,自引:0,他引:1
通过求解非定常RANS方程,选取SST k-ω湍流模型,采用全六面体网格进行离散,在忽略自由面兴波影响的情况下,对KVLCC1裸船体在深水和浅水中的PMM试验纯横荡运动粘性流场进行了数值模拟,计算了作用在船体上的水动力和力矩;通过将计算结果与现有的试验数据对比,验证了该文方法的有效性.在此基础上,根据水动力和力矩计算结果,计算得到了船舶横荡运动线性水动力导数. 相似文献
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分析铺排船液压系统的特点。基于Visual Basic开发了上位机监控系统,将液压系统的工作状态实时呈现在上位机上,对该软件的程序设计做了说明。该监控系统对于提高铺排作业效率,提升系统的稳定性有重要意义。 相似文献
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《Displays》2023
Ship surveillance plays an important role in ensuring the safety of maritime transportation and navigation. Due to the influence of factors such as waves and special weather, the existing detection methods still cannot balance the accuracy, speed and the parameters of the model in the changeable and complex marine environment. To solve this problem, this paper proposes an improved real-time method based on YOLOv5, which has few parameters and achieves high detection accuracy with little memory and computation cost. Collaborative Attention (CA) mechanism is added to the network structure, which enables the model to more accurately locate and identify target regions. We also design a Spatial Pyramid Pooling module (SPP) and a weighted pyramid network called Bidirectional Feature Pyramid Network (BiFPN) based on the characteristics of the ships to better fuse feature information. Transformer encoder is introduced to capture long-distance dependencies and preserve global and local features to the greatest extent. Furthermore, the ability of our proposed structure to localize objects at each stage is improved through integrating the output of multiple modules. The experimental results show that, the comprehensive performance of this method is better than the existing technology in ship detection on different evaluation criteria. 相似文献
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Kwang Hee Ko Taezoon Park Kyong-Hwan Kim Yonghwan Kim Dong Ho Yoon 《Computer aided design》2011,(8):848-862
In this paper, a panel generation system for analyzing seakeeping performance of a ship is developed. Given a set of offset data representing the ship hull, the system first creates a surface model of the ship. From the surface model, the wetted part of the ship is obtained by computing the intersection between the water surface and the hull, which is then processed to generate quadrilateral panels for the hull and the water surface. The system is designed to handle various kinds of ships such as ships with a mono-skeg, a twin-skeg and/or a bulbous bow in either an automatic or an interactive manner. Moreover, it can generate input panels for three different seakeeping analysis methods. Examples are provided to demonstrate the capabilities of the system. 相似文献
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In this article, efficient computational models for ship motions are presented. These models are used to simulate ship movements
in real time. Compared with traditional approaches, our method possesses the ability to cope with different ship shapes, engines,
and sea conditions without the loss of efficiency. Based on our models, we create a ship motion simulation system for both
entertainment and educational applications. Our system assists users to learn the motions of a ship encountering waves, currents,
and winds. Users can adjust engine powers, rudders, and other ship facilities via a graphical user interface to create their
own ship models. They can also change the environment by altering wave frequencies, wave amplitudes, wave directions, currents,
and winds. Therefore, numerous combinations of ships and the environment are generated and the learning becomes more amusing.
In our system, a ship is treated as a rigid body floating on the sea surface. Its motions compose of 6 degrees of freedom:
pitch, heave, roll, surge, sway, and yaw. These motions are divided into two categories. The first three movements are induced
by sea waves, and the last three ones are caused by propellers, rudders, currents, and winds. Based on Newton’s laws and other
basic physics motion models, we deduce algorithms to compute the magnitudes of the motions. Our methods can be carried out
in real time and possess high fidelity. According to ship theory, the net effects of external forces on the ship hull depend
on the ship shape. Therefore, the behaviors of the ship are influenced by its shape. To enhance our physics models, we classify
ships into three basic types. They are flat ships, thin ships, and slender ships. Each type of ship is associated with some
predefined parameters to specify their characteristics. Users can tune ship behaviors by varying the parameters even though
they have only a little knowledge of ship theory. 相似文献
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