Applied Mechanics and Materials Vols. 752-753

Abstract: Reservoir performance can be understood from system type curves. The type curve gives vivid information about maximum pressure drops, magnitude of near wellbore effects, reservoir fluid and wellbore properties needed to ascertain the strength of available drive mechanism, maximum withdrawal rates and remaining fluid in real time. This paper investigates the effects of reservoir area extent on the performance of a reservoir, subject to active bottom water, when it is completed with a vertical well. Type curves of dimensionless pressures and dimensionless pressure derivatives were produced for various dimensionless values of area extent of the reservoir. These type curves were developed from solutions to flow equations using relevant source and Green’s functions. From the results, it can be observed that the larger the reservoir area extent, the larger the dimensionless pressure drop, the longer the time it takes to attain steady state. This is validated from the pressure derivative curve, which shows that reservoirs with large area extent are characterized by longer period of radial flow and subsequently delay in the attainment of steady state, thus prolonging the arrival of bottom water.

Abstract: Apartment buildings are constructed using box frame structures that integrate slabs and wall frames, and vibrations can easily travel through these integrated box frame structures. On the other hand, such a framed structure generates fewer gaps between structural elements, assuring a superior insulation performance of airborne sound compared to wooden houses. Vertically installed equipment running through different floor levels can serve as a transmission route for airborne sound of specific frequency bands. In this study, we sought to develop technical methods to improve the inter-floor airborne sound insulation performance. To this end, we measured the sound insulation performance of floor structures and intensity levels in noise penetration areas. The sound insulation performance of the living room floor structure was measured to exceed 51 dB, which was superior to that of the restroom floor by 2–7 dB. Intensity measurements identified the central and corner areas of the living room as high-level noise areas.

Abstract: Impact sound reduction under various conditions for a total of eight different types of Floor cosverings currently used in South Korea. The results of floor impact sound within the test building under bare slab conditions indicated a high reduction rate for lightweight impact sound, but poor reduction during heavyweight impact sound testing (Bang Machine, Impact Ball). However, a reduction was identified in the mid-high frequency range (315 Hz–3150 Hz) for the lightweight impact sound, as was a reduction of approximately 2 dB–3 dB at specific frequency ranges, depending on the thickness of the floor coverings, for the heavyweight impact sound on the Ondol structure.

Abstract: Numerical modeling of honeycomb structures is too tedious and time consuming. The homogenization of these structures enables to obtain an equivalent homogeneous solid and its elastic stiffness thus to make very efficient simulations. In the present study, the skin effect is taken into consideration for the in-plane shear and torsion problems, in which the two skins are much more rigid than the honeycomb core. An analytic homogenization method, using trigonometric function series and based on the membrane plate theories, is proposed to study the influence of the honeycomb height on these properties, and the upper and lower bounds of the equivalent elastic stiffness of their curves are analyzed. A numerical H-model is established for the in-plane shear and torsion problems.

Abstract: Nowadays, the strategic value of the stratospheric airship attracts more and more attention of the countries. Based on the analysis of the working performance of the stratospheric airship, a cooling system of the electronic equipment is designed and its performance throughout the flight altitude is investigated. The results show that the single cooling system based on cold plate cannot fulfill the cooling task in the extreme hot day and a parallel cooling system as a bench should be designed .meanwhile, the temperature of the cold plate is gradually decreased and then gradually rose with the altitude. The lowest temperature in the process is-35.95°C which would has effect on the performance of the cold plate. Therefore , electrical heating system and frequency regulating speed ventilator are proposed in the above cooling system which is responsible for the electronic equipment at the optimum temperature .

Abstract: Research of devices for heat recovery is currently focused on increasing the temperature and heat efficiency of plate heat exchangers. The goal of optimization is not only to increase the heat transfer or even moisture but also reduce the pressure loss and possibly material costs. This study deals with a plate heat exchanger with wall shaped by intermittent ridges. We used software fluent and user defined deforming to deform computational mesh and create various heat exchange walls with different number of ridges and different number of set-offs. The intention of the set-offs is to discompose boundary layer inside channels created by ridges, mix the temperature field and thus intensify the heat transfer. We used previously formulated objective function, which is a linear combination of efficiency and pressure loss, and a simple local method to optimize the heat exchanger for required pressure loss. It was found that the objective function surface is monotone and unimodal, but is not smooth. The global optimums were identified and it was shown that the optimal wall shape has no set-off for low pressure losses. The optimal count of ridges and optimal count of set-offs rise with higher required pressure loss. It was proved that the suggested objective function is suitable for optimization of a counterflow plate heat exchanger, but use of a global optimization method would be beneficial.

Abstract: By analyzing the key technologies of pressure relief valve and comparing the advantages and disadvantages of existing products, liquid sealing automatic micro-pressure relief valve is designed with the properties of adjustable opening pressure, fast response rate, good sealing performance and long life, etc. Also, a reasonable mathematical model of liquid sealing automatic micro-pressure relief valve is developed, and the pressure relief valve’s opening pressure, reset pressure, relief rate and other key performance parameters is obtained. This work wil be helpful for the design and research of automatic micro-pressure relief valves used in mine rescue cabin.

Abstract: River pollution has been a well-known worldwide issue and the impacts of polluted rivers are greatly affecting the health well-being of people worldwide. Meanwhile water treatment plants (WTP) have increasing energy cost. However, an abundance of hydraulic energy is stored in the flowing river water. The hydraulic energy can be harvested to be converted into mechanical energy to operate the WTP. This paper is focused on explaining an efficient and green method to harvest hydraulic energy to reduce the energy cost incurred by the usage of motorized equipment in conventional WTP. This product has dual purpose with dual benefit of restoring the quality of river water quality as well as harvesting readily available hydraulic energy to reduce energy cost.

Abstract: A modeling through sensitivity analysis is one of the promising methods to investigate the dynamic characteristics of complex mechanical parts. This study aimed to investigate the effect of sensitivity based on mass and stiffness modification in automobile crankshaft as a function of natural frequency. Verification for the crankshaft model that is used in the experiment and simulation was done and both results showed good agreement and small errors percentage. The modification was also done by reducing the different percentage of crankshaft’s mass and stiffness. Partial differential analysis was used in the sensitivity analysis in order to figure out the natural frequency after every set of modification. According to the results, we also found that there were changes of sensitivity value by changes in mass value but the stiffness value remains unchanged. However, there is no significant effect of stiffness reduction on vibration was found in this research.

Abstract: Cooling rate plays an important role in thin wall ductile iron solidification, due to their thickness. Casting simulation is use as a tool to estimate the cooling rate. In the other hand, every microstructure has its own cooling rate. This paper explores the similarity of solidification mechanism between simulation and graphite characteristics. Three types of casting design simulated and produced. Solidification mechanism is analyzed based on cooling rate sequence and trend line matching. Temperature gradient and thermocouple function represent simulation while graphite characteristic represent experiment. The result shows that similarity in solidification mechanism is not found between simulation with experiment due to lack of parameters in both sides.