Development of a Gaussian process modeling application for the prediction of missile aerodynamic coefficients

Journal of Mechanical Science and Technology - During the process of missile development, repetitive or real-time calculation of the six-component aerodynamic coefficients is required. In general,...     

Influence of blade-tower interaction in upwind-type horizontal axis wind turbines on aerodynamics

The blade-tower interaction of upwind horizontal axis wind turbines has become important to aerodynamic loading as the systems become larger. However, there are not enough studies describing these phenomena. To investigate this interaction, we performed numerical simulations for uniform, yawed, wind shear flow conditions, and various tower cases using the nonlinear vortex correction method with time-marching free wake. At 5 m/s, the change in the normal force coefficient is approximately 10% of the average. The blade root region has a larger azimuth range of the interaction and a bigger change in aerodynamic loading. The blade-tower interaction decreases as the yaw error and wind shear exponent increases. The interaction due to tower radius variations is higher than that due to tower clearance variations. With regard to stochastic load, the blade-tower interaction may affect the total fatigue load at low wind speed and in a more unstable atmospheric condition.     

Cryptanalysis of block-wise stream ciphers suitable for the protection of multimedia and ubiquitous systems

In this paper we introduce a general framework of related-key attack on block-wise stream ciphers which are suitable for the protection of multimedia and ubiquitous systems. As a case study, we show how our cryptanalytic framework is applied to a block-wise stream cipher TWOPRIME: we construct various related-key differentials of TWOPRIME and use them to show that recovering related keys of TWOPRIME can be performed with a data complexity of 2¹⁴ known plaintext blocks and a time complexity of 2³² 8-bit table lookups. We expect that our general framework for a related-key attack would be useful tool for analyzing many of block-wise stream ciphers.     

Effect of noncondensable gas in a vertical tube condenser

An experimental study is performed to investigate the effects of noncondensable (NC) gas in the steam condensing system. A vertical condenser tube is submerged in a water pool where the heat from the condenser tube is removed by boiling heat transfer. The design of the test section is based on the passive condenser system in an advanced boiling water nuclear power reactor. Data are obtained for various process parameters, such as inlet steam flow rate, noncondensable gas concentration, and system pressure. Degradation of the condensing performance with increasing noncondensable gas is investigated. The condensation heat transfer coefficient and heat transfer rate decrease with noncondensable gas. The condensation heat transfer rate is enhanced by increasing the inlet steam flow rate and the pressure. The condensation heat transfer coefficient increases with the inlet steam flow rate, however, decreases with the system pressure. For the condenser submerged in a water pool with saturated condition, the strong primary pressure dependency is observed.     

Optimization of laminated composite structures under nonlinear dynamic loading using the equivalent static load method

Journal of Mechanical Science and Technology - As the application of composite materials increases, analysis and optimum design for various dynamic loads as well as static loads are required. In...     

Puffing of Rehmannia glutinosa enhances anti-oxidant capacity and down-regulates IL-6 production in RAW 264.7 cells

Food Science and Biotechnology - The roots of Rehmannia glutinosa (RG) have been widely used for medicinal purposes in Asia. The traditional processing of RG involves repetitive steaming and...     

Depth estimation from single monocular images using deep hybrid network

Multimedia Tools and Applications - Depth estimation is a significant task in the robotics vision. In this paper, we address the depth estimation from a single monocular image, which is a...     

A Study on Sputtered Bi-Te Thermoelectric Films with Various Compositions: Microstructure Evolution and the Effects on Thermoelectric and Electrical Properties

This study examined the sensitive effects of composition on the microstructure evolution and thermoelectric properties of sputtered Bi-Te films. Bi-Te films of various Te compositions (49 at.% to 60 at.%) were grown by cosputtering deposition and annealed at 200°C for different durations. We examined the microstructure of the films using x-ray diffraction (XRD) and transmission electron microscopy (TEM), and measured the electronic transport and thermoelectric properties. As the Te composition of the films changed from 49 at.% to 60 at.%, the phase of the as-sputtered film changed from the rhombohedral BiTe-type phase to the metastable rock-salt phase, which eventually transformed to the Bi₂Te₃-type phase upon annealing, instigating microstructure evolution. This phase transformation profoundly influenced the electrical and thermoelectric properties of the films.