Implementation of a coupled plastic damage distinct lattice spring model for dynamic crack propagation in geomaterials

This paper studies dynamic crack propagation by employing the distinct lattice spring model (DLSM) and 3‐dimensional (3D) printing technique. A damage‐plasticity model was developed and implemented in a 2D DLSM. Applicability of the damage‐plasticity DLSM was verified against analytical elastic solutions and experimental results for crack propagation. As a physical analogy, dynamic fracturing tests were conducted on 3D printed specimens using the split Hopkinson pressure bar. The dynamic stress intensity factors were recorded, and crack paths were captured by a high‐speed camera. A parametric study was conducted to find the influences of the parameters on cracking behaviors, including initial and peak fracture toughness, crack speed, and crack patterns. Finally, selection of parameters for the damage‐plasticity model was determined through the comparison of numerical predictions and the experimentally observed cracking features.     

A machine learning approach for predicting computational intensity and domain decomposition in parallel geoprocessing

ABSTRACT

High performance computing is required for fast geoprocessing of geospatial big data. Using spatial domains to represent computational intensity (CIT) and domain decomposition for parallelism are prominent strategies when designing parallel geoprocessing applications. Traditional domain decomposition is limited in evaluating the computational intensity, which often results in load imbalance and poor parallel performance. From the data science perspective, machine learning from Artificial Intelligence (AI) shows promise for better CIT evaluation. This paper proposes a machine learning approach for predicting computational intensity, followed by an optimized domain decomposition, which divides the spatial domain into balanced subdivisions based on the predicted CIT to achieve better parallel performance. The approach provides a reference framework on how various machine learning methods including feature selection and model training can be used in predicting computational intensity and optimizing parallel geoprocessing against different cases. Some comparative experiments between the approach and traditional methods were performed using the two cases, DEM generation from point clouds and spatial intersection on vector data. The results not only demonstrate the advantage of the approach, but also provide hints on how traditional GIS computation can be improved by the AI machine learning.     

Fast genetic mapping in barley: case studies of cuticle mutants using RNA-sequencing

Barley(Hordeum vulgare L.) is one of the earliest domesticated crop species and ranked as the fourth largest cereal production worldwide. Forward genetic studies in barley have greatly advanced plant genetics during the last century; however, most genes are identified by the conventional mapping method. Array genotyping and exome-capture sequencing have also been successfully used to target the causal mutation in barley populations, but these techniques are not widely adopted because of associated costs and partly due to the huge genome size of barley. This review summarizes three mapping cases of barley cuticle mutants in our laboratory with the help of RNA-sequencing. The causal mutations have been successfully identified for two of them and the target genes are located in the pericentromeric regions. Detailed information on the mapping-by-sequencing, mapping-and-sequencing, and RNA-sequencing assisted linkage mapping are presented and some limitations and challenges on the mapping assisted by RNA sequencing are also discussed. The alternative and elegant methods presented in this review may greatly accelerate forward genetics of barley mapping, especially for laboratories without large funding.     

Discovery of 13 New Variable Stars in the Field of the Open Cluster NGC 2168 （M35）

A wide-field time-series CCD photometric survey of variable stars in the field of the open cluster NGC 2168 was carried out using the BATC Schmidt telescope. In total 13 new variable stars are discovered with three W UMa systems, one EA type and two EB type eclipsing binaries (one of them could be a W UMa system), and seven pulsating stars including three candidates of δScuti stars.     

Cytoplasmic regionalization in starfish oocyte occurrence and localization of cytoplasmic determinants responsible for the formation of archenteron and primary mesenchyme in starfish (asterias amurensis) oocytes

Starfish oocytes with intact germinal vesicles (GVs) were cut along desired planes with glass needles or ligated using silk thread loops into two parts and allowed to mature in vitro, and inseminated. The experimental results showed that (1) only the parts with GVs or partial GV contents (PGVCs) cleaved, those without any GV materials did not; but nucleated and non-nucleated fragments cut from mature eggs were able to divide; (2) the development of animal parts of oocytes containing GVs or PGVCs was like that of animal fragments of matured oocytes with female pronuclei; most of them gave rise to permanent blastulae, and just a few formed ectodermal vesicles with a little primary mesenchyme; (3) a large part of vegetal fragments with GVs or PGVCs, and the vegetal parts of mature eggs without female pronuclei developed into small but normal embryos; (4) the fragments containing GVs or PGVCs obtained from the oocytes along a plane parallel to the animal-vegetal (A-V) axis developed as normally as the halves (with or without female pronuclei) severed from mature eggs along the same axis. Based on the data above, it was concluded that (1) the non-chromatin materials in the oocyte GVs are indispensable for successful fertilization and cleavage of starfish eggs; (2) some factor (s) located asymmetrically in the vegetal hemispheres of starfish oocytes is (are) responsible for formation of the archenteron and primary mesenchyme. It is evident from the above findings that the oocyte cytoplasm of the starfish had already regionalized before the GV break-down. Contribution No. 1722 from the Institute of Oceanology, Academia Sinica     

Evolution of Electric Currents Associated with Two M-Class Flares

Using one-minute cadence vector magnetograms from Big Bear Solar Observatory (BBSO), we analyze the temporal behavior of derived longitudinal electric currents associated with two flares on July 26, 2002. One of the events is an M1.0 flare which occurred in active region NOAA 10044, while the other is an M8.7 flare in the adjacent region 10039. Rapid changes of magnetic fields in the form of flux emergence are found to be associated with both of these events. However, the temporal behavior of electric currents are very different. For the M1.0 flare, the longitudinal electric current density drops rapidly near the flaring neutral line; while for the M8.7 flare, the current density rapidly increases, confirming the picture of the current-carrying flux emergence. We offer a possible explanation for such a difference: magnetic reconnection at different heights for the two events, near the photosphere for the M1.0 flare, and higher up for the M8.7 flare.     

The formation and stability of the configuration of the planetary system HD 126611

Recent Doppler velocity measurements have revealed the existence of two planets orbiting the star HD 12661 on medium-eccentricity orbits. The inner planet has a period of 263.6 d and a mass of 2.3 Jupiter masses, and the outer planet has a period of 1444.5d and a mass of 1.57 Jupiter masses. The stability of this system requires the two planets to be in a state of mean-motion orbit resonances. By numerical method we have studied the orbit migration and stability of the system in its early ages under the action of the proto-stellar disk, and calculated the probabilities of the planets being captured into the mean -motion resonances during their migrations. It is found that at present the two planets are probably situated at the edge of the 11:2 mean-motion resonance and are in chaotic motions. This result may be helpful to clarify the arguments on the present configuration. Besides, it is indicated that very probably, after the formation of the system, the gaseous disk has almost disappeared before the planets migrated to the present configuration.     

浙西北江山─绍兴断裂带构造演化特征

江山—绍兴断裂带是中国南方最重要的构造带之一。它是江南陆块与华夏陆块神功运动形成的碰撞拼贴带。它表现出明显的多期变形、构造叠加的特征：神功运动形成近东西向平卧褶皱；印支运动沿断裂带有向北西强烈的推覆挤压。断裂带不同时期的活动反映了不同特征的构造环境，形成不同的构造变形特征，并对两侧的地质历史具有明显的控制作用。     

江汉盆地钻孔测井资料确定地应力最大水平主压应力方向

利用钻孔测井资料并运用地层倾角测量信息分析法，给出了江汉盆地地应力最大水平主压应力方向为ＮＥ６０～６５°