The economic opportunities and constraints of green growth

노트 : Asie.Visions is an electronic publication dedicated to Asia. With contributions by French and international experts, Asie.Visions deals with economic, strategic, and political issues. The collection aims to contribute to the global debate and to a better understanding of the regional issues at stake. It is published in French and/or in English and upholds Ifri’s standards of quality (editing and anonymous peerreview)

Study on correlation between cavitation and pressure fluctuation signal using high-speed camera system

This paper is presenting the correlation between the cavitation and the pressure fluctuation of a propeller. Cavitation images and pressure fluctuation signals were simultaneously acquired by a high-speed camera system connected to pressure sensors for the correlation analysis. The analysis is focusing on the growing and collapsing process of the cavitation and its corresponding patterns of pressure signals. Especially, the relationship between the shape variations of the pressure fluctuation signal and the variations of pressure amplitudes for both the first and second blade frequency components is also studied. From the analysis on the correlation between cavitation behaviors and pressure fluctuation signals, comprehensive explanations on the fundamental mechanisms of the pressure signal generation and on the moment of the peak creation in the pressure signals are found. The shape of overall pressure fluctuation signal on hull surface is affected by not only the effect of cavitation from a single blade but also the superposition of the pressure signals from two adjacent blades when the collapsing of the foregoing blade's cavity and the growing of the following blade's cavity are happening at the same time. In this manner, the overlapping phenomena cause the changes of combination of amplitude levels of each blade frequency.http://deepblue.lib.umich.edu/bitstream/2027.42/84231/1/CAV2009-final27.pd

A comparison of regression models for the ice loads measured during the ice tank test

To evaluate the time-domain positioning performance of arctic marine structures, it is necessary to generate an ice load appropriate for the current position and heading of the structure. The position and orientation angle of a floating body continuously change with time. Therefore, an ice load is required for any attitude in the time-domain simulation. In this study, we present a fundamental technique for analyzing ice loads in the frequency domain based on data measured at various angles in the ice-water tank experiment. We perform spectral analysis instead of general FFT to analyze the ice load, which has the characteristics of a random signal. To generate the necessary ice load in the time domain, we must first interpolate the measured data in the frequency domain. Using the Blackman-Tukey method, we estimate the spectrum for the measured data, then process the data to generate the training set required for machine learning. Based on the results, we perform regression analysis by applying four representative techniques, including linear regression, random forest, or neural network, and compare the results with MSE. The deep neural network method performed best, but we provide further discussion for each model

Recent advances in hydrogen storage technologies based on nanoporous carbon materials

AbstractHydrogen is a promising energy carrier that can potentially facilitate a transition from fossil fuels to sustainable energy sources without producing harmful by-products. Prior to realizing a hydrogen economy, however, viable hydrogen storage materials must be developed. Physical adsorption in porous solids provides an opportunity for hydrogen storage under low-stringency conditions. Physically adsorbed hydrogen molecules are weakly bound to a surface and, hence, are easily released. Among the various surface candidates, porous carbons appear to provide efficient hydrogen storage, with the advantages that porous carbon is relatively low-cost to produce and is easily prepared. In this review, we summarize the preparation methods, pore characteristics, and hydrogen storage capacities of representative nanoporous carbons, including activated carbons, zeolite-templated carbon, and carbide-derived carbon. We focus particularly on a series of nanoporous carbons developed recently: metal–organic framework-derived carbons, which exhibit promising properties for use in hydrogen storage applications

Experimental Verification of Modal Identification of a High-rise Building Using Independent Component Analysis

Abstract Independent component analysis is one of the linear transformation methods based the techniques for separating blind sources from the output signals of the system. Recently, the method has been analytically applied to the identification of mode shapes and modal responses from the output signal of structures. This study aims to experimentally validate the blind source separation using ICA method and propose a novel method for identification of the modal parameters from the decomposed modal responses. The result of the experimental testing on the three-story steel scale model shows that the mode shapes obtained by ICA method are in good agreement with those by the analytical and peak-picking method in the frequency domain. Based on the robust mathematical model, ICA can calculate the natural frequency and damping ratio effectively using the probability distribution function of the instantaneous natural frequency determined by Hilbert transform of the decomposed modal responses and the change in the output covariance. Finally, the validity of the proposed method paves the way for more effective output-only modal identification for assessment of existing steel-concrete buildings

Spin-wave propagation in the presence of inhomogeneous Dzyaloshinskii-Moriya interactions

We theoretically investigate spin-wave propagation through a magnetic metamaterial with spatially modulated Dzyaloshinskii-Moriya interaction. We establish an effective Schrodinger equation for spin waves and derive boundary conditions for spin waves passing through the boundary between two regions having different Dzyaloshinskii-Moriya interactions. Based on these boundary conditions, we find that the spin wave can be amplified at the boundary and the spin-wave band gap is tunable either by an external magnetic field or the strength of Dzyaloshinskii-Moriya interaction, which offers a spin-wave analog of the field-effect transistor in traditional electronics.112sciescopu

Analysis of Building Energy Savings Potential for Metal Panel Curtain Wall Building by Reducing Thermal Bridges at Joints Between Panels

AbstractTo achieve national greenhouse gas reduction in the building sector, heating and cooling energy in buildings should be reduced. The government has strengthened regulations on insulation performance for building energy savings. However, the building envelope has various thermal bridges. In particular, a metal panel curtain wall comprises a number of thermal bridges at joints between the panels and the fixing units, thus degrading the overall thermal performance. To reduce building energy, it is necessary to reduce thermal bridges in building envelopes. This study aims to analyze the energy saving potential achieved by reducing thermal bridges. For this, the insulation performance and building energy needs of the existing and alternative metal panel curtain wall were evaluated. The alternative metal panel curtain wall that uses plastic molds at joints between panels and the thermally-broken brackets was suggested to reduce heat loss through thermal bridges. As results, the effective U-value of the alternative metal panel curtain wall was reduced by 72% compared with the existing metal panel curtain wall. In addition, annual heating energy needs of the alternative metal panel curtain wall building was reduced by 26%, and annual total energy needs was reduced by 6% because annual cooling energy needs of it slightly increased compared with the existing metal panel curtain wall. In conclusion, the alternative metal panel curtain wall considerably influenced the savings in building energy needs by reducing thermal bridges