ABSTRACT We study the relationship between stellar mass, star formation rate (SFR), ionization state, and gas-phase metallicity for a sample of 41 normal star-forming galaxies at 3 z 3.7. The ...gas-phase oxygen abundance, ionization parameter, and electron density of ionized gas are derived from rest-frame optical strong emission lines measured on near-infrared spectra obtained with Keck/Multi-Object Spectrograph for Infra-Red Exploration. We remove the effect of these strong emission lines in the broadband fluxes to compute stellar masses via spectral energy distribution fitting, while the SFR is derived from the dust-corrected ultraviolet luminosity. The ionization parameter is weakly correlated with the specific SFR, but otherwise the ionization parameter and electron density do not correlate with other global galaxy properties such as stellar mass, SFR, and metallicity. The mass-metallicity relation (MZR) at z 3.3 shows lower metallicity by 0.7 dex than that at z = 0 at the same stellar mass. Our sample shows an offset by 0.3 dex from the locally defined mass-metallicity-SFR relation, indicating that simply extrapolating such a relation to higher redshift may predict an incorrect evolution of MZR. Furthermore, within the uncertainties we find no SFR-metallicity correlation, suggesting a less important role of SFR in controlling the metallicity at high redshift. We finally investigate the redshift evolution of the MZR by using the model by Lilly et al., finding that the observed evolution from z = 0 to z 3.3 can be accounted for by the model assuming a weak redshift evolution of the star formation efficiency.
We study the relationship between stellar mass, star formation rate (SFR),ionization state, and gas-phase metallicity for a sample of 41 normal star-forming galaxies at \(3 \lesssim z \lesssim 3.7\). ...The gas-phase oxygen abundance, ionization parameter, and electron density of ionized gas are derived from rest-frame optical strong emission lines measured on near-infrared spectra obtained with Keck/MOSFIRE. We remove the effect of these strong emission lines in the broad-band fluxes to compute stellar masses via spectral energy distribution fitting, while the SFR is derived from the dust-corrected ultraviolet luminosity. The ionization parameter is weakly correlated with the specific SFR, but otherwise the ionization parameter and electron density do not correlate with other global galaxy properties such as stellar mass, SFR, and metallicity. The mass-metallicity relation (MZR) at \(z\simeq3.3\) shows lower metallicity by \(\simeq 0.7\) dex than that at \(z=0\) at the same stellar mass. Our sample shows an offset by \(\simeq 0.3\) dex from the locally defined mass-metallicity-SFR relation, indicating that simply extrapolating such relation to higher redshift may predict an incorrect evolution of MZR. Furthermore, within the uncertainties we find no SFR-metallicity correlation, suggesting a less important role of SFR in controlling the metallicity at high redshift. We finally investigate the redshift evolution of the MZR by using the model by Lilly et al. (2013), finding that the observed evolution from \(z=0\) to \(z\simeq3.3\) can be accounted for by the model assuming a weak redshift evolution of the star formation efficiency.
H2 and NH3 detection with low power consumption was demonstrated by integrated chemiresistive Pt and PtRh nanosheet sensors on glass substrates. The self-heating effects realized low power and local ...heating of metal nanosheet sensors, enabling the integration of sensors with different operating temperatures. Based on different resistance changes in Pt and PtRh nanosheets toward H2 and NH3, the concentration of each gas was detected from a gas mixture by consuming around 1-mW power. For decreasing the power consumption and further integration of sensors, sensor scaling and pulsed operations were numerically and experimentally studied. In addition to good connectivity of metal nanosheet sensors to large-scale integration (LSI) circuits, improvements of the power consumption by sensor scaling were proven. The pulsed operations required for integrated sensor arrays maintained a sensor response, or a resistance change, of approximately 60%, even when the power consumption was reduced by 20%.
This paper proposes a high-accuracy readout system with a high-efficient DC-DC converter. Thanks to a switching DC-DC converter with high conversion efficiency, the power loss in a regulator can be ...reduced. In the proposed system, sampling is performed using a synchronization signal generated from the switching regulator to avoid deterioration of readout accuracy caused by the ripple noise of the switching converter. Since the proposed technique does not require a large capacitor for ripple reduction, the wake-up time can be reduced, which is suitable for IoT devices operating intermittently. A prototype system developed in this work has achieved a reduction in sensor resistance readout variation to 0.006% while maintaining a high-speed wake-up.
This paper presents a coin-cell powered small size wireless sensor node with a sensor bridge biased by an energy-efficient DC-DC converter. To reduce the switching noise of the DC-DC converter, a ...Wheatstone bridge with differentially balanced in wide resistance range is used. Circuit parameters, such as bridge resistances and amplifier offset are automatically set to the optimal values in the startup sequence. Proposed sensor interface achieved power reduction by 57.3% and intermittent operation further reduces the power consumption by 78.6% from which uses LDO. The developed tiny wireless sensor node with a nanoscale gas sensor device successfully demonstrated 100ppm hydrogen gas detection.
Ppm-level hydrogen and ammonia in air were recognized by low-power, integrated sensors consisting of catalytic metal nanosheets. Thermal energy necessary for catalytic reactions were given by Joule ...heating not by external heaters. The ther-mal-aware design of sensors reduces the power consumption to 0.14 mW. The low-power and small-area properties enable large-scale, on-chip integration of molecular sensors, which will be useful in IoT era. A sensor array was successfully connected to a platform with wireless connectivity.
Ppm-level hydrogen and ammonia in air were recognized by low-power, integrated sensors consisting of catalytic metal nanosheets. Thermal energy necessary for catalytic reactions were given by Joule ...heating not by external heaters. The thermal-aware design of sensors reduces the power consumption to 0.14 mW. The low-power and small-area properties enable large-scale, on-chip integration of molecular sensors, which will be useful in IoT era. A sensor array was successfully connected to a platform with wireless connectivity.
Engineering data warehouse has been developed in order to integrate and exchange data through lifecycle of process plants. Based on a common information model, CAD data translators from 2D drawings ...and 3D models were built and their browsers have been also built. In order to adopt every task in the plant related work with its design data, such as process and instrumentation 2D drawings, a continuous refining system for drawing data has been built. With this system, a mechanism for keeping data consistency between actual project data and design data has been considered.
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