ASM: Adaptive Skinning Model for High-Quality 3D Face Modeling

The research fields of parametric face models and 3D face reconstruction have been extensively studied. However, a critical question remains unanswered: how to tailor the face model for specific reconstruction settings. We argue that reconstruction with multi-view uncalibrated images demands a new model with stronger capacity. Our study shifts attention from data-dependent 3D Morphable Models (3DMM) to an understudied human-designed skinning model. We propose Adaptive Skinning Model (ASM), which redefines the skinning model with more compact and fully tunable parameters. With extensive experiments, we demonstrate that ASM achieves significantly improved capacity than 3DMM, with the additional advantage of model size and easy implementation for new topology. We achieve state-of-the-art performance with ASM for multi-view reconstruction on the Florence MICC Coop benchmark. Our quantitative analysis demonstrates the importance of a high-capacity model for fully exploiting abundant information from multi-view input in reconstruction. Furthermore, our model with physical-semantic parameters can be directly utilized for real-world applications, such as in-game avatar creation. As a result, our work opens up new research directions for the parametric face models and facilitates future research on multi-view reconstruction

An 18.9-minute Blue Large-Amplitude Pulsator Crossing the 'Hertzsprung Gap' of Hot Subdwarfs

Blue large-amplitude pulsators (BLAPs) represent a new and rare class of hot pulsating stars with unusually large amplitudes and short periods. Up to now, only 24 confirmed BLAPs have been identified from more than one billion monitored stars, including a group with pulsation period longer than $\sim 20$ min (classical BLAPs, hereafter) and the other group with pulsation period below $\sim 8$ min. The evolutionary path that could give rise to such kinds of stellar configurations is unclear. Here we report on a comprehensive study of the peculiar BLAP discovered by the Tsinghua University - Ma Huateng Telescopes for Survey (TMTS), TMTS J035143.63+584504.2 (TMTS-BLAP-1). This new BLAP has an 18.9 min pulsation period and is similar to the BLAPs with a low surface gravity and an extended helium-enriched envelope, suggesting that it is a low-gravity BLAP at the shortest-period end. In particular, the long-term monitoring data reveal that this pulsating star has an unusually large rate of period change, P_dot/P=2.2e-6/yr. Such a significant and positive value challenges its origins from both helium-core pre-white-dwarfs and core helium-burning subdwarfs, but is consistent with that derived from shell helium-burning subdwarfs. The particular pulsation period and unusual rate of period change indicate that TMTS-BLAP-1 is at a short-lived (~10^6 yr) phase of shell-helium ignition before the stable shell-helium burning; in other words, TMTS-BLAP-1 is going through a "Hertzsprung gap" of hot subdwarfs.Comment: 26 pages, 12 figures, 4 tables, published on Nature Astronomy, URL: https://www.nature.com/articles/s41550-022-01783-

Newly formed dust within the circumstellar environment of SN Ia-CSM 2018evt

Dust associated with various stellar sources in galaxies at all cosmic epochs remains a controversial topic, particularly whether supernovae play an important role in dust production. We report evidence of dust formation in the cold, dense shell behind the ejecta–circumstellar medium (CSM) interaction in the Type Ia-CSM supernova (SN) 2018evt three years after the explosion, characterized by a rise in mid-infrared emission accompanied by an accelerated decline in the optical radiation of the SN. Such a dust-formation picture is also corroborated by the concurrent evolution of the profiles of the Hα emission line. Our model suggests enhanced CSM dust concentration at increasing distances from the SN as compared to what can be expected from the density profile of the mass loss from a steady stellar wind. By the time of the last mid-infrared observations at day +1,041, a total amount of 1.2 ± 0.2 × 10−2 M⊙ of new dust has been formed by SN 2018evt, making SN 2018evt one of the most prolific dust factories among supernovae with evidence of dust formation. The unprecedented witness of the intense production procedure of dust may shed light on the perceptions of dust formation in cosmic history

GPS/GLONASS Combined Precise Point Positioning with Receiver Clock Modeling

Research has demonstrated that receiver clock modeling can reduce the correlation coefficients among the parameters of receiver clock bias, station height and zenith tropospheric delay. This paper introduces the receiver clock modeling to GPS/GLONASS combined precise point positioning (PPP), aiming to better separate the receiver clock bias and station coordinates and therefore improve positioning accuracy. Firstly, the basic mathematic models including the GPS/GLONASS observation equations, stochastic model, and receiver clock model are briefly introduced. Then datasets from several IGS stations equipped with high-stability atomic clocks are used for kinematic PPP tests. To investigate the performance of PPP, including the positioning accuracy and convergence time, a week of (1–7 January 2014) GPS/GLONASS data retrieved from these IGS stations are processed with different schemes. The results indicate that the positioning accuracy as well as convergence time can benefit from the receiver clock modeling. This is particularly pronounced for the vertical component. Statistic RMSs show that the average improvement of three-dimensional positioning accuracy reaches up to 30%–40%. Sometimes, it even reaches over 60% for specific stations. Compared to the GPS-only PPP, solutions of the GPS/GLONASS combined PPP are much better no matter if the receiver clock offsets are modeled or not, indicating that the positioning accuracy and reliability are significantly improved with the additional GLONASS satellites in the case of insufficient number of GPS satellites or poor geometry conditions. In addition to the receiver clock modeling, the impacts of different inter-system timing bias (ISB) models are investigated. For the case of a sufficient number of satellites with fairly good geometry, the PPP performances are not seriously affected by the ISB model due to the low correlation between the ISB and the other parameters. However, the refinement of ISB model weakens the correlation between coordinates and ISB estimates and finally enhance the PPP performance in the case of poor observation conditions

Improved Memetic Algorithm for Multi-depot Multi-objective Capacitated Arc Routing Problem

The capacitated arc routing problem (CARP) is a challenging vehicle routing problem with numerous real-world applications. In this paper, an extended version of CARP, the multi-depot multi-objective capacitated arc routing problem (MDMOCARP) is proposed to tackle practical requirements. Firstly, the critical edge decision mechanism and the critical edge random allocation mechanism are proposed to optimize edges between depots. Secondly, a novel adaptive probability of local search with fitness is proposed to improve the Decomposition-Based Memetic Algorithm for Multi-Objective CARP (D-MAENS). Compared with the D-MAENS algorithm, experimental results on MD-CARP instances show that the improved memetic algorithm (IMA) has performed significantly better than D-MAENS on convergence and diversity in the metric IGD and the metric HV

Improved Memetic Algorithm for Multi-depot Multi-objective Capacitated Arc Routing Problem

The capacitated arc routing problem (CARP) is a challenging vehicle routing problem with numerous real-world applications. In this paper, an extended version of CARP, the multi-depot multi-objective capacitated arc routing problem (MDMOCARP) is proposed to tackle practical requirements. Firstly, the critical edge decision mechanism and the critical edge random allocation mechanism are proposed to optimize edges between depots. Secondly, a novel adaptive probability of local search with fitness is proposed to improve the Decomposition-Based Memetic Algorithm for Multi-Objective CARP (D-MAENS). Compared with the D-MAENS algorithm, experimental results on MD-CARP instances show that the improved memetic algorithm (IMA) has performed significantly better than D-MAENS on convergence and diversity in the metric IGD and the metric HV

High-performance Atomic Clock Modeling and Its Application in Precise Point Positioning

Presently, many IGS tracking stations have been equipped with high performance atomic clocks. In this paper, the modified Allan variance method is used to analyze the time-domain characterization of random noise of receiver clocks from different IGS tracking stations. Then, we not only evaluate the short-term stability of different types of receiver clock and the feasibility of clock modeling, but also take advantage of the observational data of Active Hydrogen Maser from IGS station in order to constrain random variation of receiver clock offset by implementing short-term clock modeling in precise point positioning(PPP) algorithm and improve positioning performance of PPP. The experiment results show that the method of clock modeling reduces the correlation between the height component, the zenith path delay and receiver clock offset parameter, the accuracy of height component can be improved by 50%. The proposed method can improve the PPP performance in crustal deformation monitoring, LEO satellite orbit determination, GNSS methodology and many other high precise GNSS geoscience fields when a high-performance atomic clock is deployed

Melatonin supplementation to the freezing medium enhances post-thaw sperm quality and fertility of giant grouper (Epinephelus lanceolatus)

Giant grouper (Epinephelus lanceolatus) is not only favored in the international live reef-fish trade but also a promising species for mariculture in coastal communities throughout Asia. Sperm cryopreservation contributes to the extensive utilization of artificial insemination in grouper aquaculture industry. Inevitable damage during the process of freezing can negatively affect post-thaw sperm quality and fertility, thus hindering its routine application in practice. Melatonin is an antioxidant that can protect sperm from the adverse effects of cryopreservation in a variety of species. This study was aimed to assess the effect of melatonin addition on post-thaw sperm function of giant grouper. Semen samples were cryopreserved with freezing medium containing different final concentrations of melatonin (1, 2 and 4 μM) and the control group (without melatonin). After thawing, multiple sperm functional parameters were evaluated. Generally, a positive effect on cryopreservation was observed for all doses of melatonin. Melatonin treatment at 1 and 2 μM seemed to be efficient in preventing sperm cryodamage, which yielded significantly higher total motility, progressive motility, mitochondrial membrane potential (P < 0.05) and improved velocity (VCL, VAP, VSL) compared to controls. Lower apoptotic-like changes were detected at 2 μM treatment. Samples frozen with melatonin also contributed to greater sperm viability and lesser DNA damage. Although not statistically different from control, a reduction in intracellular ROS was found under the melatonin treatments. Moreover, melatonin supplementation improved the fertility of frozen-thawed sperm, which increased significantly the hatching rate under a limited sperm/egg ratio (10,000:1). Hence, our study suggests inclusion of melatonin to semen extender can improve the post-thaw quality of cryopreserved giant grouper spermatozoa, the recommended concentration of melatonin is 1–2 μM in the cryomedium