The author proposed "vertically movable tension leg mooring system" in the previous paper for the purpose that an offshore floating body subject to comparatively large static horizontal loads for its scale is moored so that the occupied plane area of the mooring system may become as small as possible. And its static mooring characteristics were discussed with model calculations to demonstrate the advantages compared with the conventional tension leg mooring or the catenary mooring. In this paper, the response of the floating body and the mooring system to waves is studied to investigate the dynamic effect of the massive template hung from the floating body in the proposed system. As a result, it is demonstrated that the dynamic effect of the mooring system on the wave exciting motions of the floating body is quite small when the system is properly designed. And it is found that the tension fluctuation could generate the slack and taut repetition in the windward side mooring chain which connects the sea floor anchor and the template hung from the floating body. Finally, some guidelines to reduce such phenomenon are shown based on the parametric case study.
In this research, the numerical analysis method which can predict the residual stress distribution after tempering with sufficient accuracy was established. First, residual stress distribution of the cylinders test material after quenching and tempering was measured. Next, the creep test was done using the material after quenching, and the formula which predicts the creep strain of each material was clarified. Finally, comparison and examination of the experimental and numerical analysis value of the residual stress distribution after tempering was performed using the formula which predicts creep strain drawn from the experiment. By using the linear expansion coefficient, the yield stress of heating and cooling process of tempering, and the formula which predicts the creep strain, the residual stress distribution after tempering can be predicted with sufficient accuracy by numerical analysis. Moreover, reduction of the stress by tempering has the great influence by the fall of yield stress and creep strain, and the influence of strain resulting from a deposit of the carbide which arises in the heating process of tempering hardly affects residual stress distribution.
In this paper, we have an aim developing the next-generation-type airship for resolving airworthiness problems especially for mooring condition. For this purpose, we propose the TORUS-TYPE AIRSHIP. The torus-type airship will have the advanced characteristics of airworthiness especially at mooring condition, and have advanced maneuverability especially for movement of any direction(forward, backward, left, right, rotation), but some instability at flight condition are considered.At first, we designed a simplified torus-type airship model, and carried out towing experiments about aerodynamic characteristics of the model in upper water space of our huge towing tank instead of carrying out experiments in a wind tunnel. By introducing torus-type airship, we will be able to minimize the mooring area, reduce the maximum mooring forces, and in the result prevent the body damage at mooring. In the second, we developed a 3D Flight-simulation program using the data from the experiment. By using the numerical simulation, we can evaluate the performance of the torus-type airship from various viewpoints including mooring.
Automatic designing of piping layout is challenging since it is composed of several numerical and/or combinational optimization problems, e.g., routing problems of pipes including branches, and arrangement problems of equipments. This paper presents a new approach based on a simple idea that the branches of pipes are considered to be a variety of equipment. Accordingly, the pipe routing problems are fairly simplified by removing the branches, and it derives a lot of efficient algorithms to solve the pipe arrangement problems. One is a multi-objective genetic algorithm (MOGA) in which the gene represents both the locations of the equipments and the arrangement of the pipes. And a new simple and efficient crossover operation which appropriately merges two different piping layouts (but of course the PID is the same) is proposed. In order to provide a fairly good initial population for the MOGA, a new heuristics making use of self-organization techniques to arrange equipments is proposed. The efficiency of the proposed approach is demonstrated through two experiments, one is a designing problem including five valves, one pump, and five branches, and the other includes seven valves, one pump, and six branches. The objective of the optimization in the experiments is to minimize the length of the pipes, the number of elbows, and the valve operability cost. The algorithms are programmed using Java language. Although the automatic arrangement system used in the experiments is academic, the concept of the proposed approach will be accepted in practical systems.
