&lt;b&gt;Requirements and Transition of Onboard Reactors&lt;/b&gt;

Nakamura, Takayuki

doi:10.2219/rtriqr.62.3_179

Cited by 3 publications

(5 citation statements)

References 2 publications

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“…The results of microtremor data processing using the HVSR method in the Kalibening District, Banjarnegara obtained values f 0 and A 0 , whose distributions are shown in Figure 3. The type and soil thickness influence the value of the f 0, which is connected by the equation 𝑓𝑓 𝑜𝑜 = 𝑉𝑉 𝑠𝑠 4ℎ � where Vs is the S wave velocity, and h is the sediment thickness [9]. The softer and thicker the soil layer in a location, the lower the value of f 0 and vice versa.…”

Section: Resultsmentioning

confidence: 99%

“…This study used the HVSR method to map earthquake-prone areas in Kalibening District, Banjarnegara. The basic concept of the HVSR method is based on the observations of Nakamura and Saito on earthquake recording data in Japan and Mexico [9]. They found that the magnitude of the horizontal to vertical ratio spectrum in soft rock (Hs/Vs) has almost the same value as the ratio of the horizontal component of the soft rock to hard basement (Hs/Hb) spectrum, which is the value of the amplification factor.…”

Section: Methodsmentioning

confidence: 99%

“…Figure 2 shows the HVSR curve plot for station 7. The values of A 0 and f 0 from each station are then used to calculate the value of the seismic vulnerability index (K g ) using the equation formulated by Nakamura [9]:…”

Section: Methodsmentioning

confidence: 99%

“…One of the efforts that can be made to minimize the risk of damage due to earthquakes is to study the characteristics of the soil dynamics and create a hazard vulnerability map based on the value of the seismic vulnerability index (K g ) developed by Nakamura using the Horizontal to Vertical Spectrum Ratio (HVSR) method. [9]. This method has been widely applied worldwide to map areas prone to earthquake disasters [10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

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Analysis of Soil Dynamics and Seismic Vulnerability in Kalibening District, Banjarnegara Using the HVSR Method

Saputra

Rosid

Fachruddin

et al. 2022

J. Phys.: Conf. Ser.

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On April 18, 2018, an earthquake with a magnitude of 4.4 Mw struck the Kalibening district, Banjarnegara. The observations on the damage distribution caused by the earthquake showed something unique: the areas that suffered severe damage were concentrated in villages on hills. This observation may indicate a site-effect phenomenon due to local geological conditions. In this study, we carry out microtremor measurements at 30 stations. The measurement area includes areas that have suffered damage due to the 2018 earthquake and also with minimum damage. We analyze the microtremor observation to estimate the site’s characteristics and map the seismic vulnerability based on predominant frequency (f0 ) and amplification factor (A0 ) using the Horizontal to vertical spectrum ratio (HVSR) method. The results show that the predominant frequency in the Kalibening district area is 0.4 – 3.7 Hz, while the amplification factor is 2.5 – 10.7. The Kalibening Basin has a low f0 (<2.5 Hz) and A0 (<4), which indicates that the Kalibening Basin has a thick and soft soil type but low-density contrast. Areas with a high degree of damage have dominant frequency values in the range of 1.5 – 2.3 Hz and amplification of 5.1 – 9.2. These results suggest that the location has a high-density contrast and thick sediment, causing significant amplification. The seismic vulnerability index (Kg) values are in the range of 3.6 - 46.74. The area around the Kalibening Basin has a low Kg value, While the damaged areas have a moderate to high seismic vulnerability index.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Analysis of Soil Dynamics and Seismic Vulnerability in Kalibening District, Banjarnegara Using the HVSR Method

Saputra

Rosid

Fachruddin

et al. 2022

J. Phys.: Conf. Ser.

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“…Moreover, an interface with the feeding system should be considered. Although an ironcore inductor is useful in terms of size and weight for general applications, air-core inductors are preferred for DC electric railcars for protection coordination between the electric railcar and DC feeding system [17].…”

Section: Introductionmentioning

confidence: 99%

Determination of the Optimal Number of Phases of a Multiphase Bidirectional Chopper Considering AC Loss in Inductor

Nakamura

Murakami

2023

IEEE Access

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This study focuses on the loss of inductors in a multiphase bidirectional chopper, which is a DC-DC conversion system. The current at the inductors in a multiphase bidirectional chopper consists of a DC current equivalent to the load current and an AC current called ripple current. The discussion regarding the effect of the increased number of phases should include the loss due to the ripple current, which is caused by semiconductor switching. Therefore, this study clarifies the loss due to the ripple current from an experiment with an increase in temperature. From the extraction of AC loss from the total loss, it is demonstrated that the loss due to the ripple current is equivalent to the no-load loss in the multiphase bidirectional chopper. When the number of phases increases, the load loss decreases whereas the no-load loss increases. This relationship indicates that an optimal number of phases exist according to the load current. This study deduces an analytical solution for the optimal number of phases and applies the methodology for determining the optimal number of phases to an actual onboard bidirectional chopper for an onboard energy storage system and traction system as an example. The optimal number of phases differs depending on the application.

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Frequency Characteristics of Power Transformer for Isolated DC-DC Converter

Nakamura

Murkami

2022

IEEE Access

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The operational frequency of a transformer is an important factor in the configuration of an isolated DC-DC converter. However, discussions regarding this frequency are inadequate. This study focuses on the frequency characteristics of the transformer. The authors obtained the frequency characteristics of the impedance and the loss of the transformer to explain its fundamental attributes. When the transformer is employed for a power electronic transformer (PET), the waveform of voltage is rectangular. The loss under this waveform was obtained to observe its characteristics. Further, the issues with the isolated DC-DC converter are explained. The natural frequency, composed of leakage-inductance and equivalent-parallelcapacitance, determines the performance of the isolated DC-DC converter. When the operational frequency of the isolated DC-DC converter is below its natural frequency, the loss increases under no-load or light-load conditions. This increase in the loss is caused by the current, which contains the natural frequency of the transformer due to the ringing.

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<b>Requirements and Transition of Onboard Reactors</b>

Cited by 3 publications

References 2 publications

Analysis of Soil Dynamics and Seismic Vulnerability in Kalibening District, Banjarnegara Using the HVSR Method

Analysis of Soil Dynamics and Seismic Vulnerability in Kalibening District, Banjarnegara Using the HVSR Method

Determination of the Optimal Number of Phases of a Multiphase Bidirectional Chopper Considering AC Loss in Inductor

Frequency Characteristics of Power Transformer for Isolated DC-DC Converter

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