Parallel numerical simulation of impact crater with perfect matched layers

Impact craters are the primary geomorphic features on the surfaces of celestial bodies such as the Moon, and their formation has significant implications for the evolutionary history of the celestial body. The study of the impact crater formation process relies mainly on numerical simulation methods, with two-dimensional simulations capable of reproducing general patterns of impact processes while conserving computational resources. However, to mitigate the artificial reflections of shock waves at numerical boundaries, a common approach involves expanding the computational domain, greatly reducing the efficiency of numerical simulations. In this study, we developed a novel two-dimensional code SALEc-2D that employs the perfect matched layer (PML) method to suppress artificial reflections at numerical boundaries. This method enhances computational efficiency while ensuring reliable results. Additionally, we implemented MPI parallel algorithms in the new code to further improve computational efficiency. Simulations that would take over ten hours using the conventional iSALE-2D code can now be completed in less than half an hour using our code, SALEc-2D, on a standard computer. We anticipate that our code will find widespread application in numerical simulations of impact craters in the future.Comment: 17 pages, 8 figure

Chronology of the Basalt Units Surrounding Chang’e-4 Landing Area

The Chang’e-4 (CE-4) lunar probe, the first soft landing spacecraft on the far side of the Moon, successfully landed in the Von Kármán crater on 3 January 2019. Geological studies of the landing area have been conducted and more intensive studies will be carried out with the in situ measured data. The chronological study of the maria basalt surrounding the CE-4 landing area is significant to the related studies. Currently, the crater size-frequency distribution (CSFD) technique is the most popular method to derive absolute model ages (AMAs) of geological units where no returned sample is available, and it has been widely used in dating maria basalt on the lunar surface. In this research, we first make a mosaic with multi-orbital Chang’e-2 (CE-2) images as a base map. Coupled with the elevation data and FeO content, nine representative areas of basalt units surrounding the CE-4 landing area are outlined and their AMAs are derived. The dating results of the nine basalt units indicate that the basalts erupted from 3.42 to 2.28 Ga ago in this area, a period much longer than derived by previous studies. The derived chronology of the above basalt units establishes a foundation for geological analysis of the returned CE-4 data

Buserelin shortens the estrus-to-ovulation interval and improves the pregnancy outcomes in gilts treated with a fixed-time artificial insemination

Fixed-time artificial insemination (FTAI) is currently a standardized protocol for pig reproductive management. Efficient ovulation synchronization induced by GnRH analogs is critical for ensuring the pregnancy outcomes of FTAI. However, among the widely used GnRH analogs, the degree of synchronization and timing of ovulation remain unclear in gilts. In the present study, we focused on the estrus-to-ovulation interval, a key component in fertility management programs, and directly compared the follicular dynamics and timing of ovulation, and the subsequent pregnancy outcomes between two well-established GnRH analogs buserelin and gonadorelin. 224 prepubertal Large White gilts, randomly divided into three independent batches, were allotted to this study. The administration of PMSG was aligned with the FTAI protocol, with gonadorelin or buserelin injections administered upon detection of estrus onset in gilts. Ovarian ultrasonography was performed at the onset of estrus. Serum samples were collected for LH detection. Total piglets born, born alive, and other performance indicators were measured. Our results showed that buserelin-treated gilts exhibited an earlier ovulation, as well as a shorter estrus-to-ovulation interval and a centralized ovulation duration, with 81.5% ovulation occurring within 24–48 h after buserelin injection. Additionally, although the pregnancy rate and farrowing rate didn't differ between the two analogs, buserelin administration is beneficial for the number of total piglets and the piglet index. In conclusion, our data demonstrate that buserelin has advantages in centralizing induced ovulation and thus improving FTAI outcomes

Chronology of the Basalt Units Surrounding Chang’e-4 Landing Area

The Chang’e-4 (CE-4) lunar probe, the first soft landing spacecraft on the far side of the Moon, successfully landed in the Von Kármán crater on 3 January 2019. Geological studies of the landing area have been conducted and more intensive studies will be carried out with the in situ measured data. The chronological study of the maria basalt surrounding the CE-4 landing area is significant to the related studies. Currently, the crater size-frequency distribution (CSFD) technique is the most popular method to derive absolute model ages (AMAs) of geological units where no returned sample is available, and it has been widely used in dating maria basalt on the lunar surface. In this research, we first make a mosaic with multi-orbital Chang’e-2 (CE-2) images as a base map. Coupled with the elevation data and FeO content, nine representative areas of basalt units surrounding the CE-4 landing area are outlined and their AMAs are derived. The dating results of the nine basalt units indicate that the basalts erupted from 3.42 to 2.28 Ga ago in this area, a period much longer than derived by previous studies. The derived chronology of the above basalt units establishes a foundation for geological analysis of the returned CE-4 data

CE-4 PanCam DEM

A very high resolution DEM from CE-4 rover PanCam stereos images.</p

Advanced Research on Internal Combustion Engines and Engine Fuels

Internal combustion (IC) engines serve as power devices that are widely applied in the fields of transport, engineering machinery, stationary power generation, etc., and are evolving towards the goal of higher efficiency and lower environmental impacts. In this Editorial, the role of IC engines for future transport and energy systems is discussed, and research directions for advancing IC engine and fuel technologies are recommended. Finally, we introduce the 14 technical papers collected for this Special Issue, which cover a wide range of research topics, including diesel spray characteristics, combustion technologies for low- and zero-carbon fuels, advanced combustion mode, fuel additive effects, engine operation under extreme conditions and advanced materials and manufacturing processes