The nearby M dwarf binary GJ65 AB, also known as BL Cet and UV Cet, is a unique benchmark for investigation of dynamo-driven activity of low-mass stars. Magnetic activity of GJ65 was repeatedly ...assessed by indirect means, such as studies of flares, photometric variability, X-ray, and radio emission. Here, we present a direct analysis of large-scale and local surface magnetic fields in both components. Interpreting high-resolution circular polarization spectra (sensitive to a large-scale field geometry) we uncovered a remarkable difference of the global stellar field topologies. Despite nearly identical masses and rotation rates, the secondary exhibits an axisymmetric, dipolar-like global field with an average strength of 1.3 kG while the primary has a much weaker, more complex, and non-axisymmetric 0.3 kG field. On the other hand, an analysis of the differential Zeeman intensification (sensitive to the total magnetic flux) shows the two stars having similar magnetic fluxes of 5.2 and 6.7 kG for GJ65 A and B, respectively, although there is evidence that the field strength distribution in GJ65 B is shifted toward a higher field strength compared to GJ65 A. Based on these complementary magnetic field diagnostic results, we suggest that the dissimilar radio and X-ray variability of GJ65 A and B is linked to their different global magnetic field topologies. However, this difference appears to be restricted to the upper atmospheric layers but does not encompass the bulk of the stars and has no influence on the fundamental stellar properties.
Globalization has added new dimensions to consumers’ decision-making. Consumer Ethnocentrism is among the critical variables affecting consumers’ decisions to purchase foreign products. Consumer ...Ethnocentrism research has gained momentum in the last few decades, and a copious amount of literature is available on this subject. This article presents an overview of Consumer Ethnocentrism literature and a compressive review of research work on the relationship between “Consumer Ethnocentrism” and “Product Evaluation” with critical insights from previous literature findings. There is a fractured opinion on the subject of whether Consumer Ethnocentrism leads to a lower quality evaluation of foreign products or whether consumer preference for the domestic product is purely out of a feeling that it is unfair to buy a foreign product. We also provided future research directions using TMC (Theory, Methodology, and Context) framework in line with earlier studies.
An overview over issues and findings in SiC power MOSFET reliability is given. The focus of this article is on threshold instabilities and the differences to Si power MOSFETs. Measurement techniques ...for the characterization of the threshold voltage instabilities are compared and discussed. Modeling of the threshold voltage instabilities based on capture-emission-time (CET) maps is a central topic. This modeling approach takes the complete gate bias/temperature history into account. It includes both gate stress polarities and is able to reproduce the short-term threshold variations during application-relevant 50-kHz bipolar ac-stress. In addition, the impact on circuit operation is discussed.
China's carbon emissions trading (CET) policy aims to force relevant enterprises to implement low‐carbon technology innovation and address environmental challenges through marketization means. ...However, how China's CET policy may affect enterprise technology innovation and whether this effect may differ in industries remain to be further investigated. Therefore, based on the panel data of listed enterprises covered by the CET policy in China during 2009–2017, this paper employs the difference‐in‐difference (DID) and DID‐based propensity score matching models to evaluate the effect of CET on technology innovation. The empirical results indicate that the effect of China's CET on the technology innovation of related enterprises is generally not significant during the sample period, but this effect presents evident industrial heterogeneity. Specifically, among the eight CET‐covered industries, the CET policy helps to improve technology innovation for power and aviation enterprises but not in the other six industries (i.e., steel, chemical, building material, petrochemical, nonferrous metals, and paper), which implies that China's CET policy still has great potential for promoting the technology innovation of related enterprises. In addition, the central findings remain robust when the system generalized method of moment and DID‐based coarsened exact matching models are applied to consider the influence of omitted variables, unobservable confounders, and different matching methods.
Magnetic fields of young solar twins Rosén, L.; Kochukhov, O.; Hackman, T. ...
Astronomy and astrophysics (Berlin),
09/2016, Letnik:
593
Journal Article
Recenzirano
Odprti dostop
Aims. The goal of this work is to study the magnetic fields of six young solar-analogue stars both individually, and collectively, to search for possible magnetic field trends with age. If such ...trends are found, they can be used to understand magnetism in the context of stellar evolution of solar-like stars and to understand the past of the Sun and the solar system. This is also important for the atmospheric evolution of the inner planets, Earth in particular. Methods. We used Stokes IV data from two different spectropolarimeters, NARVAL and HARPSpol. The least-squares deconvolution multi-line technique was used to increase the signal-to-noise ratio of the data. We then applied a modern Zeeman-Doppler imaging code in order to reconstruct the magnetic topology of all stars and the brightness distribution of one of our studied stars. Results. Our results show a significant decrease in the magnetic field strength and energy as the stellar age increases from 100 Myr to 250 Myr, while there is no significant age dependence of the mean magnetic field strength for stars with ages 250−650 Myr. The spread in the mean field strength between different stars is comparable to the scatter between different observations of individual stars. The meridional field component is weaker than the radial and azimuthal field components in 15 of the 16 magnetic maps. It turns out that 89−97% of the magnetic field energy is contained in l = 1 − 3. There is also no clear trend with age and distribution of field energy into poloidal/toroidal and axisymmetric/non-axisymmetric components within the sample. The two oldest stars in this study show an octupole component that is twice as strong as the quadrupole component. This is only seen in 1 of the 13 maps of the younger stars. One star, χ1 Ori, displays two field polarity switches during almost 5 yr of observations suggesting a magnetic cycle length of 2, 6, or 8 yr.
This paper provides insights into the effect of high thermal gradients and cooling rates on equiaxed grain nucleation and growth in conditions similar to those experienced during Additive ...Manufacturing (AM) processes. Bridgman type solidification is numerically simulated with columnar grains growing at a fixed pull rate under a user-imposed thermal gradient. Controlled inoculants of known nucleation undercooling were placed ahead of the growing columnar grains to allow quantitative analysis of nucleation events. At low thermal gradient and cooling rate only the inoculants with low nucleation undercooling were activated due to low melt undercooling driven by constitutional supercooling (CS). As the cooling rate is increased, for a given thermal gradient, a larger number of inoculants with higher nucleation undercoolings were activated. At higher cooling rates, thermal undercooling was generated by a lag in the growth rate of the solid-liquid (S–L) interface compared to the theoretical pull rate. Thus, thermal undercooling becomes dominant leading to the facilitation of nucleation on less potent substrates requiring higher undercooling. The results show a transition from solute-driven undercooling to cooling rate driven thermal undercooling which contributes to the undercooling that activates the nucleation events. Invoking the Interdependence model, it is also shown that the high cooling rate induced thermal undercooling reduces the size of the nucleation free zone substantially.
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•HCO3–/CO32– species leads to changed pH enhancing PMS mediated transformation.•PMS mediated processes are generally inhibited by I– due PMS consumption.•Cl– influences the observed transformation ...likely due to HOCl generation and reactions.•Br–/PMS induces varied degradation kinetics and mechanisms compared to PMS alone.•HA/phenol/pyridine/sorbate has minimal influence on PMS induced transformation.
The rapid and selective peroxymonosulfate (PMS) induced transformation of H1-antihistamines cetirizine (CET) and diphenhydramine (DPH) can be influenced by the presence of common organic and inorganic water constituents. Presence of HCO3– and/or CO32–, which often exhibit powerful inhibition on the advanced oxidation processes (AOPs), can enhance the PMS mediated transformation of CET/DPH. The observed promotion is demonstrated by the changed solution pH through detailed kinetic studies. The impact of halide ions is remarkable, with I– inhibiting the process through consumption of PMS, while Cl– increases slightly the transformation kinetics through the formation and subsequent reactions of HOCl. The CET/DPH degradation in the Br–/PMS system is influenced by the generation of reactive species such as HOBr which leads to different reaction pathways as compared to PMS alone. The results demonstrated the performance of PMS can be tailored through varying the experimental parameters. In addition, the presence of model organic constituents found in water, e.g., humic acid, phenol, pyridine or sorbate, has a minimal effect on the PMS mediated oxidation processes, highlighting the strong application potential of PMS in water treatment.
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Under the background of green certificate trading (GCT)‑carbon emission trading (CET) market, the application of P2P trading in regional integrated energy system (RIES) has not been fully explored, ...and it is urgent to design a reasonable prosumer P2P trading mechanism to adapt to the development of diversified electricity market. Therefore, this paper proposes a prosumer P2P cooperative trading model based on generalized Nash bargaining. Specifically, based on the differential modeling of various types of prosumers, this paper constructs a prosumer P2P cooperative trading model based on generalized Nash bargaining theory, and quantifies the bargaining power of prosumers through the contribution value of interactive operation. The GCT-CET collaborative mechanism is introduced to promote the consumption of distributed energy by transforming carbon quotas through green certificates. In addition, this paper designs a warm start and adaptive step alternating direction multiplier method decentralized algorithm (WAS-ADMM) to improve the solution efficiency and protect the trading privacy of prosumers. Through a case study, it analyzes the impact of prosumers' P2P cooperative trading on the consumption of distributed energy, prosumers' GCT-CET costs and comprehensive costs in the context of GCT and CET market. The simulation results show that the proposed trading model reduces the GCT-CET costs of the prosumers' alliance by about 24.98%.
•A P2P cooperative trading model of integrated energy is constructed based on GNB.•A GCT-CET collaborative mechanism is proposed to promote the consumption of renewable energy.•An improved decentralized algorithm based on WAS-ADMM is designed to solve the P2P trading model.
The high-resolution, dual channel, visible and near-infrared spectrograph CARMENES offers exciting opportunities for stellar and exoplanetary research on M dwarfs. In this work we address the ...challenge of reaching the highest radial velocity precision possible with a complex, actively cooled, cryogenic instrument, such as the near-infrared channel. We describe the performance of the instrument and the work flow used to derive precise Doppler measurements from the spectra. The capability of both CARMENES channels to detect small exoplanets is demonstrated with the example of the nearby M5.0 V star CD Cet (GJ 1057), around which we announce a super-Earth (4.0 ± 0.4
M
⊕
) companion on a 2.29 d orbit.
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