A comparison of the local spiral structure from Gaia DR2 and VLBI maser parallaxes

Context. The Gaia mission has released the second data set (Gaia DR2), which contains parallaxes and proper motions for a large number of massive, young stars. Aims. We investigate the spiral structure in the solar neighborhood revealed by Gaia DR2 and compare it with that depicted by VLBI maser parallaxes. Methods. We examined three samples with different constraints on parallax uncertainty and distance errors and stellar spectral types: (1) all OB stars with parallax errors of less than 10%; (2) only O-type stars with 0.1 mas errors imposed and with parallax distance errors of less than 0.2 kpc; and (3) only O-type stars with 0.05 mas errors imposed and with parallax distance errors of less than 0.3 kpc. Results. In spite of the significant distance uncertainties for stars in DR2 beyond 1.4 kpc, the spiral structure in the solar neighborhood demonstrated by Gaia agrees well with that illustrated by VLBI maser results. The O-type stars available from DR2 extend the spiral arm models determined from VLBI maser parallaxes into the fourth Galactic quadrant, and suggest the existence of a new spur between the Local and Sagittarius arms.Comment: 4 pages, 3 figures, 1 table, accepted for publication in A&

All roads lead to the places of your interest: An on-demand, ride-sharing visitor transport service

Successful visitor transport within large tourist sites should balance visitor experience and operating costs. Inspired by the model of sharing economy, we design a “user-centered” intelligent visitor transport system to improve the efficiency and quality of experience of transport service in large tourist sites. The system’s core approach is a three-stage heuristic model based on Pareto optimality. Results of the proposed service indicate a drastic reduction of visitor delay time and an improvement in energy efficiency. The proposed scheduling schemes for organizers are more diversified and adaptable than the existing service

The cumulative effects of known susceptibility variants to predict primary biliary cirrhosis risk.

Multiple genetic variants influence the risk for development of primary biliary cirrhosis (PBC). To explore the cumulative effects of known susceptibility loci on risk, we utilized a weighted genetic risk score (wGRS) to evaluate whether genetic information can predict susceptibility. The wGRS was created using 26 known susceptibility loci and investigated in 1840 UK PBC and 5164 controls. Our data indicate that the wGRS was significantly different between PBC and controls (P=1.61E-142). Moreover, we assessed predictive performance of wGRS on disease status by calculating the area under the receiver operator characteristic curve. The area under curve for the purely genetic model was 0.72 and for gender plus genetic model was 0.82, with confidence limits substantially above random predictions. The risk of PBC using logistic regression was estimated after dividing individuals into quartiles. Individuals in the highest disclosed risk group demonstrated a substantially increased risk for PBC compared with the lowest risk group (odds ratio: 9.3, P=1.91E-084). Finally, we validated our findings in an analysis of an Italian PBC cohort. Our data suggested that the wGRS, utilizing genetic variants, was significantly associated with increased risk for PBC with consistent discriminant ability. Our study is a first step toward risk prediction for PBC

Experimental Study on Dynamic Welding of AgW60, CuW60 and Cu Contact Materials in Symmetrical and Asymmetric Pairing at 270VDC/200A

With the use of contact material simulating test device, experiments are conducted for the contact materials AgW60, CuW60 and Cu and their different pairing under the conditions of DC voltage and current 270VDC/200A and surrounding atmosphere of carbon dioxide and nitrogen. The welding resistance, average welding force and the relationship between welding force and the number of operations during welding were measured and analyzed. Experiments show that the anti-welding ability of the three materials in the symmetric pairing of carbon dioxide and nitrogen is ranked as AgW60>Cu>CuW60. The "intermediate effect" occurs in the anti-welding properties of the asymmetric pairing. The relationship between the number of operations required for each welding and the average average welding force is approximately an inverse proportional function

Research on gesture recognition based on support vector machine

In response to the problems of low recognition accuracy and large computation of traditional neural network algorithms, a gesture recognition detection model is designed by using human skin color features and SVM model with gesture classification recognition as the target. The method adopts bilateral filtering and other graphical processing to smooth the edges of the palm, detect and binarize the skin color of the region, and filter the binarized image to smooth the edges. The skin color space is transferred from the RCB space to the YUV space under which the gesture region is separated from the background, and morphological processing techniques are introduced in terms of gesture integrity to effectively fill the black hole region and remove the white dot region in the gesture picture, and directly edge the gesture picture. After obtaining the standardized image, the feature values are obtained. The experimental results show that the method improves the accuracy of gesture recognition compared with traditional algorithms

A hybrid classication algorithm based on svm, ann and knn for gesture recognition

A hybrid model based on SVM, ANN, KNN is proposed, which improves the accuracy compared to the traditional gesture recognition algorithm by combining it with the traditional gesture recognition algorithm

The influence of structural defects on intra-granular critical currents of bulk MgB2

Bulk MgB2 samples were prepared under different synthesis conditions and analyzed by scanning and transmission electron microscopy. The critical current densities were determined from the magnetization versus magnetic field curves of bulk and powder-dispersed-in-epoxy samples. Results show that through a slow cooling process, the oxygen dissolved in bulk MgB2 at high synthesis temperatures can segregate and form nanometer-sized coherent precipitates of Mg(B,O)2 in the MgB2 matrix. Magnetization measurements indicate that these precipitates act as effective flux pinning centers and therefore significantly improve the intra-grain critical current density and its field dependence.Comment: 4 pages, 4 figures, to be published in IEE Transactions in Applied Superconductivit