The article deals with the subject matter related to the development of underwater works technologies. Nearly 15 years ago one of the authors of this study published a material in the monthly magazine of “Podwodny Świat” (The Underwater World) entitled “The Future of Underwater Technologies – the diver or the robot?” where he noted that the time of great changes in technologies aimed at researching the depths and conducting works under water has arrived. This new era mainly consists in the fact that on an increasing number of occasions the diver is replaced by an underwater robot. The presented material constitutes an attempt to provide an answer to the question whether the then posed thesis is still valid. In the article the authors discuss issues concerned with the development of techniques and technologies applied in the conquest of depths that leads them to the conclusion that the previously observed tendency of a double-tracked development of underwater technologies is gaining in strength, which causes that the works and exploration of bodies of water at great depths will be possible only with the use of unmanned techniques.
The determination of how efficiently filtration systems used for the production of breathing air used in hyperbaric environments are operating is significant both from theoretical and practical points of view. The quality of breathing air and the breathing mixes based on air is crucial with regard to divers' safety. Paradoxically, a change in regulations regarding quality requirements for breathing mixes has imposed the necessity to verify both the technical equipment and laboratory procedures used in their production and verification. The following material, which is a continuation of previous publications, presents results of the conducted research along with the evaluation of effectiveness of the filtration systems used by the Polish Navy.
This is the first part of the material concerned with the analysis of drive systems in remotely controlled unmanned underwater vehicles. The paper discusses the problem of classification of UUVs, mainly remotely controlled, with an indication of four different approaches to this issue. Moreover, the article discusses the nomenclature used in relation to various components of the discussed drive systems and thrusters, as well as indicates the functionality of such systems along with the advantages and disadvantages of the analysed design solutions. The method of analysis of drive systems, its methodology and the results will be the subject of a subsequent publication of the authors.
This is the first publication from a series of articles devoted to the issues of underwater exploration carried out for litigation purposes. The present paper suggests that an exploration strategy should be defined as: all actions that aim at creating and implementing a plan of exploration, conducted with the application of a defined exploration methodology - here understood to refer to the technical way the task is completed. Such an approach is taken in order to ensure the most adequate involvement of means and resources for the plan’s implementation. Since the choice of strategy affects many aspects that range from the technical to the environmental, this first part focuses on the location of the exploration and the anticipated conditions.
Determining the efficiency of breathing air purification for hyperbaric purposes with the use of filtration systems is of a crucial importance. However, when the Polish Navy took samples of breathing air from their own filtration plant for quality purposes, these were found to not meet the required standard. The identification of this problem imposed the need to undertake actions aimed at the elimination of the identified disruptions in the process of breathing air production, with the objective of assuring its proper quality. This study presents the results of the initial tests on the air supply sources utilised by the Polish Navy, which were carried out for the purpose of setting a proper direction of future works and implementing corrective measures in order to optimise the breathing air production process. The obtained test results will be used in a subsequent publication devoted to the assessment of the level of efficiency of air purification with the use of a multifaceted approach consisting in the utilisation of various types of air supply sources and different configurations of purification systems.
The material presents an analysis of the impact that the parameters of air hyperbaric exposure have on the time remaining to the beginning of the first ventilation, as calculated with two mathematical models. The research has been conducted in the form of simulations that take into account standard parameters of exposure. Differences between the analysed models have been indicated, and the influence of the changes of particular input values in the analysed models on the output values has been defined.
The article demonstrates use of underwater remotely operated vehicles during an underwater visual inspection of a sunken vessel. The presented tasks were carried out in the course of underwater works performed from a Polish navy rescue vessel on the fishing boat WŁA-127. The discussed examples include a visual inspection of the sunken vessel and the support offered to Polish Navy rescue divers as they carried out underwater works.
The article presents the general construction of an underwater vehicle manipulator along with a discussion of the materials used in their construction. The types of drive systems used by the manipulator have been characterised, distinguishing their advantages and disadvantages. The functions of the manipulator are specified in relation to the activities performed by it. Moreover, the paper discusses the manipulator's degrees of freedom with the specification of the formula for their calculation. The basic types of end effectors are presented as well as an outline of the classification of manipulators in relation to the tasks carried out.
Fu Qiang, Chen Ming, Wang Xiuli, Zhu Rongsheng, Zhang Guoyu and Yu Jianen
The micro air nucleus widely distributed in the ocean is a necessary condition for the cavitation of hydraulic machinery in seawater. In order to study the stability of air nucleus in seawater and cavitation inception, the computational domain of water molecules with air nucleus was studied using the method of molecular dynamics simulation, and the transient characteristics of air nucleus in liquid water were obtained. The key factors influencing nuclei stability were analyzed. The results showed that air nucleus with a certain mass could maintain the dynamic equilibrium in liquid water. The internal density of air nuclei had a critical value that allowed the nuclei to stably exist in water. The air nuclei mass was the decisive factor in its equilibrium volume in water, and the two were positively correlated. The internal density of air nuclei was negatively correlated with the nuclei radius when the nuclei was stable in water. Liquid surface tension was an important factor affecting the stability of the air nuclei. The larger the initial radius of nuclei, the smaller the water pressure, and the more likely the cavitation occurs.
The paper deals with the diffusion equation for pore water pressures with the source term, which is widely promoted in the marine engineering literature. It is shown that such an equation cannot be derived in a consistent way from the mass balance and the Darcy law. The shortcomings of the artificial source term are pointed out, including inconsistencies with experimental data. It is concluded that liquefaction and the preceding process of pore pressure generation and the weakening of the soil skeleton should be described by constitutive equations within the well-known framework of applied mechanics. Relevant references are provided