Search

To study the impact of faults on the enrichment and mobility of shale oil in the Gulong area, representative rock samples were selected in this paper. Based on geochemical data and chemical kinetics methods, coupled with shale oil enrichment and mobility analysis techniques, the shale oil generation quantity and in situ oil content were evaluated from the perspectives of shale oil generation and micro migration, and the mobility of shale oil was revealed. At the same time, the hydrocarbon expulsion efficiency (HEE) of shale was qualitatively and quantitatively characterized, combined with the development of faults. The research results indicate that the study area mainly develops organic-rich felsic (ORF)/organic-containing felsic (OCF) shale, their proportion in both wells exceeds 65%, and the resource amount is the largest in this type of lithofacies. The development of a fault controls the enrichment of shale oil, and the in situ oil content and oil saturation index (OSI) of the shale in well Y58, which is close to the fault, are significantly worse than those in well S2. Well Y58 has 9.52 mg/g and 424.83 mg/g TOC respectively, while well S2 has 11.34 mg/g and 488.73 mg/g TOC respectively. The fault enhanced the migration of shale oil, increasing the efficiency of oil expulsion. As a result, the components with weak polarity or small molecules, such as saturated hydrocarbons and low carbon number n-alkanes, are prone to migration, reducing the mobility of shale oil. [ABSTRACT FROM AUTHOR]

Plant height, as a crucial component of plant architecture, exerts a significant influence on rapeseed (Brassica napus L.) lodging resistance, photosynthetic efficiency, yield, and mechanized harvest level. A previous study identified dwarf rapeseed LSW2018. In this study, LSW2018 (dwarf parent (PD)) was crossed with 389 (high parent (PH)) to establish the F2 population, and 30 extremely dwarf (bulk–D) and high (bulk–H) plants in the F2 population were respectively selected to construct two bulked DNA pools. Whole–genome sequencing and variation analysis (BSA–seq) were performed on these four DNA pools (PD, PH, bulk–D, and bulk–H). The BSA–seq results revealed that the genomic region responsible for the dwarf trait spanned from 19.30 to 22.19 Mb on chromosome A03, with a length of 2.89 Mb. After fine mapping with simple sequence repeat (SSR) markers, the gene was narrowed to a 0.71 Mb interval. Within this region, a total of 113 genes were identified, 42 of which contained large–effect variants. According to reference genome annotation and qRT–PCR analysis, there are 17 differentially expressed genes in this region between high and dwarf individuals. This study preliminarily reveals the genetic basis of LSW2018 dwarfing and provides a theoretical foundation for the molecular marker–assisted breeding of dwarf rapeseed. [ABSTRACT FROM AUTHOR]

The application of the case teaching method in the equipment contract management course can overcome the limitation of the traditional teaching method which emphasizes the theory and ignores practice, and is conducive to improving the students’ comprehensive quality and the teachers’ scientific research ability and professional level. The paper mainly introduces the standards of the case selection and the classification of the teaching contents in the application of the case teaching method in the course of the equipment contract management, and puts forward some opinions on other problems that should be paid attention to in the current case teaching of the equipment contract management.

The Proterozoic oil in Gaosheng area of the Western Depression of Liaohe Basin has great potential and is an important exploration field. However, the study about control factors of Gaosheng reservoir needs to be improved. The source rocks are characterized by using geochemical techniques and the structural evolution history is restored by using 2D-Move software. The characteristics of reservoirs and caps are clarified, and the controlling factors of reservoir formation are summarized. The oil generation intensity of Es4 and Es3 is generally 5 χ 106-10 χ 106 t/km2, indicating that the oil source is sufficient. The sandstone reservoir has fracture and dissolution porosity, which provide storage space for oil accumulation. Faults and unconformities provide pathways for oil migration. The dense Fangshenpao and Mesozoic basalt is a good cap layer to preserve the reservoir, which effectively prevents the upward migration of oil. According to the comprehensive analysis of main controlling factors, the favorable exploration areas are pointed out. The research results are of great significance to guide the future oil and gas exploration in Liaohe Basin. [ABSTRACT FROM AUTHOR]

For the speed-tracking control of permanent magnet synchronous motor (PMSM) systems, fast dynamic response and high reference speed require a large transient current to provide sufficient electromagnetic torque. However, the excessive transient current may damage the drive circuit and threaten the system safety. Besides, it is also important to pay attention to the influence of multiple disturbances including system parameter uncertainties and unknown load torque variation. To solve these problems, we propose a nonlinear speed-tracking control approach for uncertain PMSM systems. More specifically, based on the cascade control structure and by introducing auxiliary smooth function, we first develop a nonlinear current-constrained controller (CCC) to guarantee the speed tracking, disturbance rejection, and overcurrent protection simultaneously. In order to improve the robustness of the desired performances, we further implement extended state observer (ESO) techniques to propose an ESO-based CCC (ESO-CCC). Finally, comparative experiments are implemented in a 5.5 kW PMSM platform to verify the performance of the proposed two controllers. [ABSTRACT FROM AUTHOR]

The effects of uniaxial tensile strain in the x direction (εx) on the mechanical properties of the Al6MgNb compound were explored by carrying out first-principles calculations based on the density functional theory (DFT). The calculation results showed that the Al6MgNb compound was stable in mechanics at a uniaxial tensile strain range of 0–12%. The shear modulus G, bulk modulus B and Young's modulus E of the Al6MgNb compound all decreased as the uniaxial tensile strain εx grew from 0 to 12%, exhibiting the negative sensitivities of elastic moduli to uniaxial tensile strain. The Poisson ratio ν of the Al6MgNb compound grew with the increase in uniaxial tensile strain εx from 0 to 7%, exhibiting the positive sensitivity of Poisson's ratio to uniaxial tensile strain, but it decreased as the uniaxial tensile strain εx increased from 7% to 12%, exhibiting its negative sensitivity to the uniaxial tensile strain. The Al6MgNb compound possesses the optimal toughness under a uniaxial tensile strain εx of 7% because of the largest value of ν. The Vickers hardness HV of the Al6MgNb compound decreased first and then remained stable with the growth in uniaxial tensile strain εx from 0 to 12%, exhibiting the significant negative sensitivity of the Vickers hardness to tensile uniaxial strain at a strain range of 0–7%. The ratio of the bulk modulus B to the elastic shear modulus G (i.e., B/G) increased first and then decreased with the growth in uniaxial tensile strain εx from 0 to 12%. The highest ductility is achieved for the Al6MgNb compound at a strain εx of 7% because of the largest value of B/G. The compression anisotropy percentage AB, shear anisotropy percentage AG and the universal anisotropy index AU of the Al6MgNb compound all increased as the uniaxial tensile strain εx increased from 0 to 12%, exhibiting the positive sensitivity of elastic anisotropy to the uniaxial tensile strain. Our study suggested that the mechanical properties of the Al6MgNb compound can be influenced and regulated by applying proper uniaxial tensile strain. These findings can provide a favorable reference to the study on mechanical performance of Al-Mg-based materials by means of strain modulation. [ABSTRACT FROM AUTHOR]