Asteroseismology of the δ\delta Scuti star HD 50844

Aims. We aim to probe the internal structure and investigate more detailed information of the $\delta$ Scuti star HD 50844 with asteroseismology. Methods. We analyse the observed frequencies of the $\delta$ Scuti star HD 50844 obtained by Balona (2014), and search for possible multiplets based on the rotational splitting law of g-mode. We tried to disentangle the frequency spectra of HD 50844 by means of the rotational splitting only. We then compare them with theoretical pulsation modes, which correspond to stellar evolutionary models with various sets of initial metallicity and stellar mass, to find the best-fitting model. Results. There are three multiplets including two complete triplets and one incomplete quintuplet, in which mode identifications for spherical harmonic degree $l$ and azimuthal number $m$ are unique. The corresponding rotational period of HD 50844 is found to be 2.44$^{+0.13}_{-0.08}$ days. The physical parameters of HD 50844 are well limited in a small region by three modes identified as nonradial ones ($f_{11}$, $f_{22}$, and $f_{29}$) and by the fundamental radial mode ($f_{4}$). Our results show that the three nonradial modes ($f_{11}$, $f_{22}$, and $f_{29}$) are all mixed modes, which mainly represent the property of the helium core. The fundamental radial mode ($f_{4}$) mainly represents the property of the stellar envelope. In order to fit these four pulsation modes, both the helium core and the stellar envelope must be matched to the actual structure of HD 50844. Finally, the mass of the helium core of HD 50844 is estimated to be 0.173 $\pm$ 0.004 $M_{\odot}$ for the first time. The physical parameters of HD 50844 are determined to be $M=$ 1.81 $\pm$ 0.01 $M_{\odot}$, $Z=$ 0.008 $\pm$ 0.001. $T_{\rm eff}=$ 7508 $\pm$ 125 K, log$g=$ 3.658 $\pm$ 0.004, $R=$ 3.300 $\pm$ 0.023 $R_{\odot}$, $L=$ 30.98 $\pm$ 2.39 $L_{\odot}$.Comment: 11 pages, 7 figures, 6 tables, accepted for publication in A&

Calibration of shielded microwave probes using bulk dielectrics

A stripline-type near-field microwave probe is microfabricated for microwave impedance microscopy. Unlike the poorly shielded coplanar probe that senses the sample tens of microns away, the stripline structure removes the stray fields from the cantilever body and localizes the interaction only around the focused-ion beam deposited Pt tip. The approaching curve of an oscillating tip toward bulk dielectrics can be quantitatively simulated and fitted to the finite-element analysis result. The peak signal of the approaching curve is a measure of the sample dielectric constant and can be used to study unknown bulk materials.Comment: 10 pages, 3 figure

Rail accessibility on property value: Zuoying Station

Problem/Purpose: Accessibility to transport infrastructure is one of the factors that affects property value. A number of researchers have found positive and negative effects on how improvement in public transportation has on property value (Chau and Ng, 1998). In Taiwan, little research has been carried out in this area. This research seeks to contribute to the understanding of the effect of rail accessibility on property value. Specifically, this study investigates the impact on property value located in close proximity to Zuoying station in Taiwan. Hedonic price theory is used and 5,478 data sets including property transaction prices, house or unit size; distances to the rail station, amenities, parklands and main roads were used for the testing. Before and after the commencement of the rail systems has also been considered in this study. Design/methodology/approach: Hedonic analysis is a well-established technique that is applied in this study. Findings: The estimation results suggest that accessibility to train station is one of the important factors affecting property values. It is found that the shorter distance and easier access the rail station, the higher the property values. Research limitations/implications (if applicable): This research has considered the elements of before and after the opening of the Taiwan High Speed Rail (THSR) and Kaohsiung Mass Rapid Transit (KMRT). However, a comparison study on the effects of before and after the completed rail development is not included in this study. Takeaway for practice (if applicable) Originality/value: No study has been conducted in the past on Zuoying station in the area of rail accessibility and property values. This is the only rail station in southern Taiwan where three railway systems converge. The investment of new transport infrastructure has positive impact on the land values in the locality and the economic and social aspects of the built environment