Evolution of residual strain and strain energy in rocks under various types of uniaxial cyclic loading-unloading

In the process of roadway excavation, the rock mass around the roadway is often subjected to cyclic loads, and the rock mechanical properties and strain energy evolution under cyclic loads are obviously different from those under compression, so it is urgent to carry out research on rock mechanical properties and strain energy evolution under cyclic loads. This study aims to investigate the evolution of residual strain and strain energy in rocks under uniaxial cyclic loading-unloading experiments (UCLUE). Four types of rocks, namely coal, white sandstone, red sandstone, and granite, were subjected to uniaxial compression experiments (UCE) and various uniaxial cyclic loading-unloading experiments (UEACLUE). The findings are as follows: analysis of UEACLUE revealed a gradual decrease in residual strain with an increasing number of cycles, leading to its eventual disappearance. However, if the cyclic loading-unloading (CLU) was continued beyond this point, the rocks displayed a reappearance of residual strain. The number of cycles required to eliminate residual strain was found to be inversely proportional to the peak strength of the rocks, while directly proportional to the upper limit value of UCLUE. Among the different stages of the uniaxial cyclic loading and unloading test, the plastic stage of white sandstone exhibited the largest disparity in dissipated strain energy, followed by the plastic stage of red sandstone, with coal displaying the smallest difference. Analysis of dissipated strain energy in the four types of uniaxial cyclic loading and unloading tests revealed differences of 0.00348 mJ▪mm−3, 0.03488 mJ▪mm−3, 0.02763 mJ▪mm−3, and 0.01619 mJ▪mm−3 in the plastic stage for the respective rock types. Furthermore, examination of the input strain energy density (ISED) and dissipated strain energy density (DSED) during the CLU process showed a linear relationship between these variables. Additionally, the investigation of ISED and DSED in other types of UCLUE demonstrated adherence to the cyclic-linear dissipation law (CLDL). The study of mechanical properties and strain energy evolution under CLU is of positive significance for the development of rock fatigue damage and rock damage mechanics

Effects of length-to-diameter ratio and strain rate on strain energy accumulation and dissipation in sandstone

To investigate the influence of the length-to-diameter (L/D) ratio and strain rate on the evolution of strain energy of sandstone under uniaxial compression, experimental tests were conducted using the RMT-150B rock mechanics test system. Specifically, uniaxial compression experiments (UCE), uniaxial loading-unloading experiment(ULUE) and uniaxial cyclic loading-unloading experiments (UCLUE) were performed. The results show that: 1) Based on an investigation of the Kaiser effect in UCLUE, it is postulated that a small degree of loading-unloading has negligible impact on the storage of strain energy in rock masses. The hypothesis regarding the limited influence of loading-unloading on the elastic strain energy storage of rocks is confirmed through a comparative analysis between the elastic strain energy storage in UCLUE and ULUE. 2) By analyzing the ESED and ISED of sandstone under different L/D ratios and strain rates, it is found that it follows the linear energy storage law. The evolution of elastic strain energy is not affected by strain rate. Therefore, the UCLUE at any strain rate can analyze the elastic strain energy of uniaxial compression experiment with the same size at any strain rate, and provide a new method for strain energy analysis at different length-diameter ratios and strain rates. 3) When the stress of sandstone samples of equal size is equal, the smaller the strain rate, the longer the loading experiment of sandstone, the more time the friction development and interconnection of cracks in sandstone are, and the more dissipated strain energy and input strain energy are generated. 4) Smaller L/D ratios are associated with larger ESED and DSED values in sandstone. As the stress intensifies, the ESED and DSED of certain sandstones with larger L/D ratios experience a sharp increase when approaching the failure stress. Under equal stress levels, it is possible for sandstones with larger L/D ratios to exhibit higher ESED and DSED values compared to those with smaller L/D ratios

Distribution Channel Choice and Divisional Conflict in Remanufacturing Operations

We consider a firm consisting of two divisions, one responsible for designing and manufacturing new products and the other responsible for remanufacturing operations. The firm will sell these new and remanufactured products either directly to the consumer (direct selling) or through an independent retailer (indirect selling). Our study demonstrates that a firm’s organizational structure can affect its marketing decisions. Specifically, a decentralized firm with separate manufacturing and remanufacturing divisions can benefit from indirect selling with higher firm profit, supply chain profit, and total consumer demand than direct selling. Moreover, this structure also induces a remanufacturable product design. In contrast, a centralized firm in which the manufacturing and remanufacturing divisions are consolidated is intuitively better off by choosing direct selling than indirect selling. Furthermore, we show that, surprisingly, when the focal firm sells through an independent retailer, a decentralized internal structure can result in higher supply chain profit than a centralized internal structure. We further investigate the case of dual dedicated channels and conclude that, while direct selling of remanufactured products and indirect selling of new products can better induce a remanufacturable product design and higher supply chain profit, it is not in the best interest of the firm in terms of total sales and firm profit

Unexpected CRISPR off-target mutation pattern in vivo are not typically germline-like [preprint]

A computationally evolutionary investigation was performed to re-analyze the WGS data of the two studies published in Nature Methods (2015, 2017) with opposite conclusions on CRISPR off-target mutations. Our analysis concluded that the so-called unexpected SNVs pattern obtained by the study of Schaefer et al. are not typically germline-like. Some of unusual and unidentified mutations may arise, but the real reasons remain to be explored. Based on the available data and a direct comparison of the two studies, we presented two possible reasons and future re-analysis directions that may contribute to such different conclusions. To characterize the authentic CRISPR-mediated mutations, we are required to have appropriate controls to rule out other sources of mutations, which will be needed for benchmarking of targeting safety of CRISPR-based gene therapy

L’argumentation sur la titulature impériale dans la dynastie Ming au prisme de la « Théorie généralisée de l’argumentation »

Le recours à la « Théorie généralisée de l’argumentation » cherche à dégager les règles et les structures de l’argumentation dans la controverse dite du « Grand Rituel » autour de la titulature impériale. Notre analyse montre que le Proposant et l’Opposant adhèrent tous deux à l’ancien système politique et aux traditions culturelles anciennes et se réfèrent aux classiques et à des événements historiques du passé afin de défendre leurs thèses. L’argumentation concernant cette question est démontrée via ces règles. En résumé, cet article montre que : 1) la Théorie généralisée de l’argumentation et sa méthode acceptent le pluralisme culturel (culture dominante incluse) ; 2) il est possible de décrire et d’évaluer des arguments en recourant à une interprétation socio-culturelle.By using the Generalized Argumentation Theory, this paper tries to reveal the rules and structures of the argumentation about the imperial title issue in the Great Ritual Controversy. Our analysis shows that both the protagonist and the antagonist follow ancient Chinese political system and cultural traditions, and appeal to ancient classics and historical events in order to defend their claims. With these rules, the argumentation about the issue is demonstrated. Finally, this paper shows that: 1) Generalized Argumentation Theory and its methods are tolerant of cultural pluralism (including mainstream culture); 2) it is feasible to describe and evaluate arguments through socio-cultural interpretation

A Survey of Deep Learning-Based Object Detection

Object detection is one of the most important and challenging branches of computer vision, which has been widely applied in peoples life, such as monitoring security, autonomous driving and so on, with the purpose of locating instances of semantic objects of a certain class. With the rapid development of deep learning networks for detection tasks, the performance of object detectors has been greatly improved. In order to understand the main development status of object detection pipeline, thoroughly and deeply, in this survey, we first analyze the methods of existing typical detection models and describe the benchmark datasets. Afterwards and primarily, we provide a comprehensive overview of a variety of object detection methods in a systematic manner, covering the one-stage and two-stage detectors. Moreover, we list the traditional and new applications. Some representative branches of object detection are analyzed as well. Finally, we discuss the architecture of exploiting these object detection methods to build an effective and efficient system and point out a set of development trends to better follow the state-of-the-art algorithms and further research.Comment: 30 pages,12 figure

A Wide-Bandwidth Monopolar Patch Antenna with Dual-Ring Couplers

A new center-fed circular patch antenna with two coupled annular rings is presented. When the two annular rings are coupled properly, a wide band from 5.45 GHz to 7.16 GHz is achieved with a monopole-like radiation pattern. Measured results show that the antenna with a low profile of 0.027 wavelengths (at 5.45 GHz) has a bandwidth of 27.1% and a measured maximum gain of 6 dBi. The radiation pattern is omnidirectional and remains relatively stable within the operating band

Evolution of the class C GPCR Venus flytrap modules involved positive selected functional divergence

<p>Abstract</p> <p>Background</p> <p>Class C G protein-coupled receptors (GPCRs) represent a distinct group of the GPCR family, which structurally possess a characteristically distinct extracellular domain inclusive of the Venus flytrap module (VFTM). The VFTMs of the class C GPCRs is responsible for ligand recognition and binding, and share sequence similarity with bacterial periplasmic amino acid binding proteins (PBPs). An extensive phylogenetic investigation of the VFTMs was conducted by analyzing for functional divergence and testing for positive selection for five typical groups of the class C GPCRs. The altered selective constraints were determined to identify the sites that had undergone functional divergence via positive selection. In order to structurally demonstrate the pattern changes during the evolutionary process, three-dimensional (3D) structures of the GPCR VFTMs were modelled and reconstructed from ancestral VFTMs.</p> <p>Results</p> <p>Our results show that the altered selective constraints in the VFTMs of class C GPCRs are statistically significant. This implies that functional divergence played a key role in characterizing the functions of the VFTMs after gene duplication events. Meanwhile, positive selection is involved in the evolutionary process and drove the functional divergence of the VFTMs. Our results also reveal that three continuous duplication events occurred in order to shape the evolutionary topology of class C GPCRs. The five groups of the class C GPCRs have essentially different sites involved in functional divergence, which would have shaped the specific structures and functions of the VFTMs.</p> <p>Conclusion</p> <p>Taken together, our results show that functional divergence involved positive selection and is partially responsible for the evolutionary patterns of the class C GPCR VFTMs. The sites involved in functional divergence will provide more clues and candidates for further research on structural-function relationships of these modules as well as shedding light on the activation mechanism of the class C GPCRs.</p

Evolutionary conservation of nested MIR159 structural microRNA genes and their promoter characterization in Arabidopsis thaliana

MicroRNAs (miRNAs) are endogenous small RNAs, that are vital for gene expression regulation in eukaryotes. Whenever a pri-miRNA precursor includes another miRNA precursor, and both of these precursors may generate independent, non-overlapping mature miRNAs, we named them nested miRNAs. However, the extent of nested miR159 structural evolutionary conservation and its promoter characterization remains unknown. In this study, the sequence alignment and phylogenetic analysis reveal that the MIR159 family is ancient, and its nested miR159 structures are evolutionary conserved in different plant species. The overexpression of ath-MIR159a, including the 1.2 kb downstream region, has no effect on rescuing the mir159ab phenotype. The promoter truncation results revealed that the 1.0 kb promoter of ath-MIR159a is sufficient for rescuing the mir159ab phenotype. The cis-regulatory elements in the ath-miR159a promoters indicated functions related to different phytohormones, abiotic stresses, and transcriptional activation. While the MybSt1 motif-containing region is not responsible for activating the regulation of the miR159a promoter. The qRT-PCR results showed that overexpression of ath-MIR159a led to high expression levels of miR159a.1–5 and miR159a.1–3 and complemented the growth defect of mir159ab via downregulation of MYB33 and MYB65. Furthermore, continuously higher expression of the miR159a.2 duplex in transgenic lines with the curly leaf phenotype indicates that miR159a.2 is functional in Arabidopsis and suggests that it is possible for a miRNA precursor to encode several regulatory small RNAs in plants. Taken together, our study demonstrates that the nested miR159 structure is evolutionary conserved and miRNA-mediated gene regulation is more complex than previously thought

Anisotropy and energy evolution mechanism of rock mass under true triaxial loading-unloading

In the process of underground excavation, the surrounding rock is in a very complex stress environment, especially under the influence of its anisotropy, the occurrence of dynamic disaster is hidden. In this paper, the loading and unloading tests of sandstone in different principal stress directions were carried out by using the true triaxial unloading disturbed rock test system. The mechanical properties and failure characteristics of true triaxial under different principal stresses were studied, the energy evolution mechanism in other directions induced by loading and unloading of different principal stresses was analyzed. Results showed that under the influence of rock mass secondary stress anisotropy, during the cyclic loading and unloading process of the first principal stress, the strain in other directions shows opposite deformation. The volumetric strain compresses first and then expands, and the final volumetric strain shows a macroscopic phenomenon of expansion. When the third principal stress of high confining pressure rock mass is unloaded, the first principal stress produces a compression deformation, while the second and third principal stresses produce an expansion deformation. The deformation of the second principal stress is less than that of the third principal stress, and the deformation in unloading direction changes from linear elastic state to elastic-plastic nonlinear state. The accumulated energy of rock mass is a great difference between the first principal stress unloading and the third principal stress unloading. The energy variation characteristics of unloading in the dominant direction determine the energy accumulation and release law in the other two induced directions. The limit stored energy of the third principal stress unloading rock decreases, and the second principal stress accelerates the rock failure with the increase of the first principal stress, which verifies that the rock is easier to be destroyed by unloading than by loading. The higher the unloading rate of the third principal stress, the higher the energy released and the lower the dissipated energy, and the lower the energy density and total accumulated energy density in the unloading direction of rock mass. The main cause of dynamic accidents is the accumulation and release of energy in rock mass. The secondary anisotropy of rock mass has a great influence on the ultimate stored energy of rock mass. The study on the influence characteristics of three-dimensional loading and unloading secondary stress on the ultimate stored energy of rock mass provides a reference for preventing rock burst