Current Issue : January - March Volume : 2020 Issue Number : 1 Articles : 5 Articles
Interest in hybrid propulsion systems that can be used on small vessels has increased\nsignificantly in recent years. They can replace inefficient and environmentally burdensome\nconventional systems based on diesel engines. Hybrid propulsion has many advantages such as\nhigh energy efficiency and virtually noiseless operation, and therefore it fits well with the current\ntrends of â??green shippingâ? and â??zero emissionâ?. The aim of the research conducted was to examine\nand analyse the varied energy demand of a small inland ferry with electric propulsion depending\non the navigation strategy. The work included tests carried out on a model of the vessel.\nConventional resistance tests involving towing the model at a constant speed proved to be of no use\nfor the unit, which, during a short voyage, moves with variable speeds and manoeuvres. Therefore,\natypical and unique tests were performed to determine the energy consumption during the\nacceleration of the unit and the parameters of navigation with the propulsion turned off. The work\nresulted in calculated forecasts of energy consumption by the ship depending on the adopted\ncruising style and a proposal of the most energy-efficient way to cross the shipping route connecting\nthe two banks of the Motlawa River in the city of Gdansk....
With the rapid development of inertial technology, the rotational inertial system has been widely used for high-accuracy\nnavigation. In addition, the single-axis rotational inertial navigation system is one of the most popular navigation systems due\nto its low cost. However, the fact which cannot be ignored is that although single axis rotational inertial navigation system can\nrestrain divergence of attitude error, it cannot eliminate velocity error, which is mainly caused by the gyro misalignment and\nscale factor error related to rotational axis. A novel calibration method established on filter has been proposed. Position,\nvelocity, and attitude are chosen to be the state variables. In order to estimate the gyro errors related to rotational axis, these\nerrors must be included in the state equation. Correspondingly, zero velocity and rate of turntable are chosen to be measured.\nSimulation has been carried out to verify the correctness of the theory, and the real test has been performed to further\ndemonstrate the validity of the method. By compensating the main error estimated by filter, it can be found that the accumulated\nerrors in velocity and attitude are decreased. So, the precision of navigation is greatly improved with the\nproposed method....
Icing of wires is a product of rain, fog, and freezing rain, and is a common\nmeteorological disaster in winter in Guizhou Province of China. It is extremely\nharmful to facilities such as power transmission and communication\nlines, and has caused huge economic loss up to 48.9566 billion dollars a year.\nBased on the meteorological records of Guizhou from 1967, we analyze the\nmeteorological characteristics during the icing of wires, and obtain the temperature,\nwind speed and direction conditions of the ice accident. The icing of\nwires is carried out by supercooling raindrops, freezing of the clouds, freezing\nand spreading on the wires. Different types of supercooled raindrops and\ncloud freezing and freezing processes will form different types of ice accretion;\nwind direction and wind speed will affect the growth of ice accretion by\nchanging the speed of sub-cooling raindrops and cloud falling. The weight of\nrain-type ice accretion is between 24 and 152 g, and the weight of smog-type\nice is between 40 - 76 g. The average ice density of these two places can be\ncalculated to be 0.2 - 0.5 g/cm3. The longer the icing of wires, the higher the\nice disaster rate....
To achieve privacy protection in the k-anonymity algorithm, replacing the starting positions of k users with the center of the\ncloaked area results in the route from the starting position to the center of the cloaked area probably nonlinear, which will bring\nout the inconvenience for the user. This paper proposes a new anonymous server framework, on which we add the function of\nelectronic map and navigation compared to the original one based on the framework of k-anonymity for LBS. In addition to the\noriginal tasks including computing the center of cloaked area O and the actual query result ri corresponding to the query qi, the\nanonymous server with the new architecture will plan the actual path ..........................
We report the results of optical spectroscopic monitoring observations of a T\nTauri star, V409 Tau. A previous photometric study indicated that this star\nexperienced dimming events due to the obscuration of light from the central\nstar with a distorted circumstellar disk.......................
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