Optimisation of the Thin-Walled Composite Structures in Terms of Critical Buckling Force

The paper presents the optimisation of thin-walled composite structures on a representative sample of a thin-walled column made of carbon laminate with a channel section-type profile. The optimisation consisted of determining the configuration of laminate layers for which the tested structure has the greatest resistance to the loss of stability. The optimisation of the layer configuration was performed using two methods. The first method, divided into two stages to reduce the time, was to determine the optimum arrangement angle in each laminate layer using finite element methods (FEM). The second method employed artificial neural networks for predicting critical buckling force values and the creation of an optimisation tool. Artificial neural networks were combined into groups of networks, thereby improving the quality of the obtained results and simplifying the obtained neural networks. The results from computations were verified against the results obtained from the experiment. The optimisation was performed using ABAQUS® and STATISTICA® software.

Wireless power transfer using multiple-transmitters for high stability for position

The aim of this study is to optimize the system in the wireless power supply using multiple transmitters by algebraically analyzing the effects of both a circuit parameters and an axis displacement, etc. In addition to these analyses, the other aim is designing, producing and evaluating wireless charger with high stability for position. In the proposed method, we analyzed the situation in which three transmitters are used as power sources. It is turned out that the optimum arrangement of three transmitters is equilateral triangular from Biot-Savart law and circuit equation. In the experiment, transmitted power is measured when the receiver is moved on the vertical plane in regard to central axis of coils. It is confirmed that 4~4.5mW is transmitted at the face-to-face of transmitters and 2.4mW is transmitted at the center of transmitters.

Optimum Arrangement Design of Mastic Ropes for Membrane-Type LNG Tanks Considering the Flatness of Thermal Insulation Panel and Production Cost

Thermal insulation panels are installed on the inner walls of liquefied natural gas (LNG) tanks of an LNG carrier to maintain the cryogenic temperature. Mastic ropes are used to attach thermal insulation panels to the inner walls and to fill the gap between the walls and panels. Because the inner walls of the LNG tanks can be corrugated owing to production errors, a large amount of mastic ropes are required to maintain the flatness of the thermal insulation panels. Therefore, in this study, an optimization method is proposed to minimize the total amount of mastic ropes for satisfying the flatness criterion of thermal insulation panels. For this purpose, an optimization problem is mathematically formulated. An objective function is used to minimize the total amount of mastic ropes considering constraints to flatten the thermal insulation panels. This function is applied to the design of membrane-type LNG tanks to verify the effectiveness and feasibility of the proposed method. Consequently, we confirm that the proposed method can provide a more effective arrangement design of mastic ropes compared with manual design.

Ballistic performance of multi-metal systems

Ballistic resistance enhancement of armours and structures has been a prominent area of research over the years. Monolithic metallic plates have been the preferred choice for armours against high-velocity projectiles. High-strength steel is a popular choice for such systems. However, the high areal density deters in accommodating such systems in practical applications which require lightweight products. On the contrary, multi-metallic systems produced by the combination of low-density materials with similar or superior ballistic resistance as their monolithic counterparts have become attractive candidates in defence applications. However, only a limited number of comprehensive studies on the ballistic performance of multi-metal multi-layered targets are available in the literature. Moreover, these studies have drawn contradictory conclusions on the optimum arrangement of different layers and materials within the systems. In addition, existing knowledge in this area is scattered in the literature and there is a need to collate them to enhance the development of multi-metal multi-layered ballistic-resistant plate systems in order to be optimised for ballistic-related armour. This article aims to provide a comprehensive review of the effect of different metals, thickness, fracture mechanisms, feasibility of the connection types and the order of the metallic plates within targets on the ballistic performance.

Optimum arrangement of two-stage plug and concentrate recycling RO systems using thermodynamic and exergy analysis

Purpose This paper aims to determine the optimum arrangement of a reverse osmosis system in two methods of plug and concentrate recycling. Design/methodology/approach To compare the optimum conditions of these two methods, a seawater reverse osmosis system was considered to produce fresh water at a rate of 4,000 m3/d for Mahyarkala city, located in north of Iran, for a period of 20 years. Using genetic algorithms and two-objective optimization method, the reverse osmosis system was designed. Findings The results showed that exergy efficiency in optimum condition for concentrate recycling and plug methods was 82.6 and 92.4 per cent, respectively. The optimizations results showed that concentrate recycling method, despite a 36 per cent reduction in the initial cost and a 2 per cent increase in maintenance expenses, provides 6 per cent higher recovery and 19.7 per cent less permeate concentration than two-stage plug method. Originality/value Optimization parameters include feed water pressure, the rate of water return from the brine for concentrate recycling system, type of SW membrane, feedwater flow rate and numbers of elements in each pressure vessel (PV). These parameters were also compared to each other in terms of recovery (R) and freshwater unit production cost. In addition, the exergy of all elements was analyzed by selecting the optimal mode of each system.