Using a steady state Reynolds Averaged Navier–Stokes solver, a numerical study of the ship-to-ship interaction during a lightering operation is presented. Since the Froude number is very low, the ...double model approximation is adopted and sinkage and trim neglected. At the first stage, five different combinations of water depth, speed, and ship-to-ship distance in the transverse and longitudinal directions are used as benchmark test cases. The wave pattern, pressure distribution and forces and moments acting on the two hulls are predicted. A good correspondence between the measured and computed waves is noted, indicating that the pressure on the free surface is well predicted. Assuming that the pressure is accurate also on the hull, the variation in forces and moments between the cases is explained. Comparisons with measured data and with similar computations carried out elsewhere are made. It is seen that the present results correspond better with other computations than with the data. In the second stage, a set of systematic computations is carried out to study the ship-to-ship interaction in shallow water. The forces and moments, as well as the sinkage and trim on the hulls with varying relative longitudinal or transverse position are predicted and explained.
•We investigate ship-to-ship interaction in shallow water by numerical tools.•Numerical tools are validated using measured data and other computations.•Numerical results offer physical explanations of ship-to-ship interaction.•Systematic investigations provide general knowledge of interaction effects.
Accurate resistance performance evaluation is essential to predict the minimum propulsion horsepower required for ships in real sea. Therefore, in this paper, the added resistance performance of ...K-Supramax in various wave conditions was calculated using CFD (Computational Fluid Dynamics). First, to compare the resistance performance according to the DOF (Degree of Freedom), the added resistance performance in the head regular wave was investigated and compared with the experiment. The 2DOF and 6DOF results in the head regular wave had no significant differences. Second, to compare the resistance performance among various wave conditions, the effect of the heading angle was analyzed by comparing resistance and motion RAOs (Response Amplitude Operators) in bow quartering sea conditions using 6DOF. The added resistance showed the highest value near the resonance frequency of 170°. As the heading angle increased, the added resistance tended to decrease, regardless of the wavelength ratio. Also, the added resistance performance in irregular waves was investigated with reference to the adverse conditions. The spectral method, which linearly superimposes regular wave results, and the added resistance generated during irregular waves directly through CFD were compared. The resistance in irregular waves increased by approximately 92% for the spectral method and by approximately 72% for the direct irregular wave calculation compared to the resistance in calm water. In addition, the PSD (Power Spectral Density) of resistance and the distribution of motion RAOs obtained from direct irregular wave calculations were investigated.
We consider a situation, when braking is the only way to avoid obstruction of an automotive vehicle or a railroad train with a suddenly detected steadfast obstacle blocking the path. The velocity at ...the moment of the impact is viewed as a natural and a suitable criterion of the severity of the impact and, hence, of the very likelihood of the accident. Assuming that this velocity is distributed in accordance with the Rayleigh law, it is shown that the corresponding available sight distance (ASD) treated as a non-random function of the random impact velocity follows the exponential distribution. The variability (uncertainty) of the ASD measurements by the navigation system's Radar(s) and/or Lidar(s) is assessed assuming that these measurements are normally distributed random variables. It is determined that the accuracy of these measurements, when the actual ASD is short and because of that the expected level of the impact velocity and, hence, the probability of the obstruction, are significant, is as important as the actual, objective, measurement independent ASD. The obtained information can be useful when choosing, developing and employing Radars and/or Lidars as effective navigation devices in various vehicular human-system-integration/interaction (HSI) technologies. This is true not only for the particular automotive or railroad situations in question, but also in other areas of vehicular engineering, such as, say, aerospace (e.g., when landing on Mars or on the Moon) or in maritime engineering (e.g., when encountering an obstacle, like another vessel or an iceberg, or when establishing an adequate under-keel clearance for large tankers navigated in shallow waters).
Dark Days at Noon provides a broad history of wildfire in North America, from pre-European contact to the present. Edward Struzik sheds light on what may happen in the future if we do not learn to ...live with fire as Indigenous people once did, so that we may learn from how we managed fire in the past and apply those lessons in the future.
In the conditions of port activities, the object of protection is the natural environment, primarily water and aquatic biological resources, as the most sensitive to external influences. The issues ...of environmental risk assessment are considered as measures for the protection of water resources in the face of an increase in cargo flows of a large seaport. Firstly, the risk of accidents during sea bunkering operations, and secondly, the environmental risk (the risk of introducing bioinvasions with ballast water) during deballasting of sea vessels. The general scheme for assessing environmental risk in relation to the components of the natural environment is considered. The number of bunkering operations in a large seaport has been calculated (2200 - 2500 per year in recent years). On the basis of statistical data, the frequency of accidents with oil spills during bunkering operations was found. Its numerical value was 2.9 · 10-4 1 a year per one operation. The volume of deballasting of individual sea terminals and the entire port has been determined - 55 million m3 per year. Basins for primary ballast intake for tankers and dry-cargo ships have been determined for ship entries to the loading port in 2020. This makes it possible to rank the discharged ballast according to the level of environmental risk (risk of bioinvasions), which is determined by the basin of its primary intake and/or transit time.
Driving heavy vehicles with dangerous cargo involves various work environments that can significantly impact road safety. This research aims to study the impact of oil and gas tanker drivers’ work ...environment on driving performance to identify and address any issues that may affect their ability to carry out their jobs effectively. To achieve this, a quantitative approach was employed using a questionnaire survey adapted from the literature review. The data collected from a sample of drivers of oil- and gas-heavy vehicles were analyzed using structural equation modelling. The study’s findings reveal a significant association between the drivers’ work environment and driving performance, represented by a path coefficient of β = 0.237. These results highlight the substantial contribution of the work environment to driving performance, with an effect of 63%. Consequently, the study emphasizes the importance of considering the work environment as a potential factor when assessing and enhancing tanker drivers’ driving abilities during oil and gas transportation.
Modeling the effects of leakage in the transport of hazardous liquids is a highly topical issue, not only in the field of environmental engineering. This article’s introduction presents relevant ...information and statistical sources, analyzes selected scientific and professional publications, and characterizes the results of selected research projects. The applied approaches, methods, and results of our research specify the processes of developing and testing a theoretical model of spreading the impacts of leakage of hazardous liquids on biological components of the environment. The proposed model for predicting the environmental impacts of hazardous liquid (HL) leakage during transport is a crucial risk management tool in the planning of transport of dangerous goods. It also enables the creation of comprehensive information systems that monitor the transport unit in real-time, indicate the presence of significant habitats along the transport route, and draw attention to possible threats, in particular to the health and lives of people and the environment. The main result of the presented research is the application of a computational model for determining the parameters of the dangerous zone in case of HL leakage and its graphical plotting along the transport route, estimating the probability of impacting the selected place by leaking HL. The model application results are presented in the form of calculated frequency of impacting the set of points in the vicinity of the HL transport route. Defined standardized frequencies of HL infiltration above a specified limit in liters per square meter in the event of leakage of the entire volume of HL from a road tanker (leaked volume of 30 m3) form the basic set of information for creating relevant risk maps near busy traffic routes and subsequent selection of ecologically and spatially optimal routes.
In this work, the possible benefits obtained due to the implementation of evaporative emissions control measures, originating from vehicle fueling processes, on ozone concentrations are verified. The ...measures studied are: (1) control at the moment when the tank trucks supply the fuel to the gas stations (Stage 1); (2) control at the moment when the vehicles are refueled at the gas stations, through a device installed in the pumps (Stage 2); (3) same as the previous control, but through a device installed in the vehicles (ORVR). The effects of these procedures were analyzed using numerical modeling with the VEIN and WRF/Chem models for a base case in 2018 and different emission scenarios, both in 2018 and 2031. The results obtained for 2018 show that the implementation of Stages 1 and 2 would reduce HCNM emissions by 47.96%, with a consequent reduction of 19.9% in the average concentrations of tropospheric ozone. For 2031, the greatest reductions in ozone concentrations were obtained with the scenario without ORVR, and with Stage 1 and Stage 2 (64.65% reduction in HCNM emissions and 31.93% in ozone), followed by the scenario with ORVR and with Stage 1 and Stage 2 (64.39% reduction in HCNM emissions and 32.98% in ozone concentrations).
The paper focuses on analysis of the effect of various surveys and inspections on the psychophysical behaviour of the crew. After analysing the scope and the extent of each regime, the authors ...identified more than 60% of surveys overlapping each other. Furthermore, the results of the survey conducted among seafarers indicate that the present method of carrying out ship surveys and inspections have a negative effect on the psychophysical condition of the crew. Therefore, a new method of tanker inspections has been proposed in order to reduce the psychophysical strain of the crew. The proposed method would minimise the annual duration of the inspections up to 30% and improve inspection time coordination without compromising quality and safety of the ships.
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