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Takushima, Akira,Han, Hyung-Suk,Jung, Wei-Bong The Society of Air-Conditioning and Refrigerating 2009 International Journal of Air-Conditioning and Refr Vol.17 No.2
It is well known that a refrigerant-induced noise is caused by two-phase flow in the indoor unit of a heat pump air-conditioner. Especially when the flow pattern in a pipe is intermittent flow, the irregular noise occurs frequently. But it is very difficult to avoid this kind of the noise for the application of air-conditioner. Therefore, in this research, the flow patterns at two-phase flow state in a pipe of the indoor unit for the air-conditioner are researched using cycle simulator at typical cycle conditions. In order to find the relationship between refrigerant-induced noise and flow pattern, the noise patterns are investigated with respect to the estimated flow pattern from the various flow pattern maps. Base on the estimations of the flow patterns by those maps, the refrigerant-induced noise is evaluated as decreasing tube diameter, which can transit the flow pattern from slug to annular flow.
Measurements of Minute Unsteady Pressure on Three-Dimensional Fan with Arbitrary Axis Direction
Hirata, Katsuya,Fuchi, Takuya,Onishi, Yusuke,Takushima, Akira,Sato, Seiji,Funaki, Jiro Korean Society for Fluid machinery 2010 International journal of fluid machinery and syste Vol.3 No.1
The present study is a fundamental approach to develop the measuring technology for minute fluctuating pressures on the three-dimensional blade surfaces of the fan which rotates with an arbitrary rotation-axis direction. In this situation, we are required to correct the centrifugal-force effect, the gravitational-force effect and the other leading-error effects for accurate measurements of the minute pressures. The working fluid is air. A pressure transducer rotating with an arbitrary attitude is closely sealed by a twofold shroud system. The rotational motion with an arbitrary attitude is produced by fixing the pressure transducer to the cantilever which is connected to a motor-driven disc of 500mm in diameter and 5mm in thickness. As a result, we have quantitatively determined main governing effects upon the non-effective component of the pressure-transducer signal.
Effects of Reflection in RSOA-Based WDM PON Utilizing Remodulation Technique
Cho, Keun Yeong,Lee, Yong Jik,Choi, Hyeon Y.,Murakami, Ayako,Agata, Akira,Takushima, Yuichi,Chung, Yun C. IEEE 2009 Journal of Lightwave Technology Vol.27 No.10
<P> We investigate the effects of the discrete reflection on the performances of upstream and downstream signals in the wavelength-division-multiplexed passive optical network (WDM PON) implemented in a single-fiber loopback configuration using the reflective semiconductor optical amplifiers (RSOAs). We first analyze the optical beat interference (OBI) noise caused by the discrete reflection, and clarify the relation between the reflection tolerance and the network's operating conditions such as the RSOA gain, the link loss, and the location of the reflection point, etc. The results show that the impact of the reflection can be expressed by using the effective crosstalk level. We then measured the reflection tolerance of the RSOA-based WDM PON, in which the downstream signal operating at 1.25 Gb/s is remodulated by the RSOA at the subscriber's site for the transmission of 155-Mb/s upstream signal. The reflection tolerances are measured to be in the range of <TEX>$-42$</TEX> to <TEX>$- 35~\hbox{dB}$</TEX> for the downstream signals and <TEX>$-29$</TEX> to <TEX>$-19~\hbox{dB}$</TEX> for the upstream signals, depending on the RSOA gain. These small reflection tolerances are caused by the fact that the reflected light is re-amplified by the RSOA. We also show that the dependence of the reflection tolerance on the RSOA gain can be explained by using the effective crosstalk level. These results are used to evaluate the impacts of the unwanted discrete reflections on the RSOA-based WDM PON. </P>