Dynamic response and limit analysis of buried gas pipeline under ground consolidation load

Currently, the significant dynamic plastic deformation of a buried gas pipeline frequently occurs due to the ground construction process that acts as a direct threat to the operation security of a buried gas transmission system. In this study, the pipe-soil interaction structure under a dynamic consolidation load, such as high energy dynamic compaction load, was considered as a non-conservative system in the work. Two parts of structure dissipation energy were introduced into the Lagrange function, and the elastoplastic dynamic equations of a non-conservative system based on the Hamilton Variation Principle (HVP) and the finite element (FE) theory were established. Implicit solution schemes were proposed based on the dynamic equations, and a steel weight-soil-buried pipeline finite element model was developed by performing a dynamic analysis in the LS-DYNA software with an explicit format. Vivid impact responses of an underground pipeline associated with the buried depth, wall thickness, and tamping energy were simulated. The plastic failure criterion of high toughness pipeline steel indicates that treated pipeline buried depth, wall thickness, and tamping energy corresponded to the generalized loads, and limit state of a specific case. So, they were recognized via the relationship of generalized load in relation to the total strain of pipelines. This was performed by using tangent intersection criteria, two elastic slope criteria, and zero curvature criteria. Additionally, the von Mises yield stress criterion was also applied as a traditional approach. The study potentially offers significant references on the quantitative pre-evaluation of a buried gas pipeline that poses as a threat due to the occurrence of third-party damage such as extreme strong ground interference

Loss of endothelial hypoxia inducible factor-prolyl hydroxylase 2 induces cardiac hypertrophy and fibrosis

BACKGROUND: Cardiac hypertrophy and fibrosis are common adaptive responses to injury and stress, eventually leading to heart failure. Hypoxia signaling is important to the (patho)physiological process of cardiac remodeling. However, the role of endothelial PHD2 (prolyl-4 hydroxylase 2)/hypoxia inducible factor (HIF) signaling in the pathogenesis of cardiac hypertrophy and heart failure remains elusive. METHODS AND RESULTS: Mice with Egln1Tie2Cre (Tie2-Cre-mediated deletion of Egln1 [encoding PHD2]) exhibited left ventricular hypertrophy evident by increased thickness of anterior and posterior wall and left ventricular mass, as well as cardiac fibrosis. Tamoxifen-induced endothelial Egln1 deletion in adult mice also induced left ventricular hypertrophy and fibrosis. Additionally, we observed a marked decrease of PHD2 expression in heart tissues and cardiovascular endothelial cells from patients with cardiomyopathy. Moreover, genetic ablation of Hif2a but not Hif1a in Egln1Tie2Cre mice normalized cardiac size and function. RNA sequencing analysis also demonstrated HIF-2α as a critical mediator of signaling related to cardiac hypertrophy and fibrosis. Pharmacological inhibition of HIF-2α attenuated cardiac hypertrophy and fibrosis in Egln1Tie2Cre mice. CONCLUSIONS: The present study defines for the first time an unexpected role of endothelial PHD2 deficiency in inducing cardiac hypertrophy and fibrosis in an HIF-2α– dependent manner. PHD2 was markedly decreased in cardiovascular endothelial cells in patients with cardiomyopathy. Thus, targeting PHD2/HIF-2α signaling may represent a novel therapeutic approach for the treatment of pathological cardiac hypertrophy and failure

Integrin β3 Mediates the Endothelial-to-Mesenchymal Transition via the Notch Pathway

Background/Aims: Neointimal hyperplasia is responsible for stenosis, which requires corrective vascular surgery, and is also a major morphological feature of many cardiovascular diseases. This hyperplasia involves the endothelial-to-mesenchymal transition (EndMT). We investigated whether integrin β3 can modulate the EndMT, as well as its underlying mechanism. Methods: Integrin β3 was overexpressed or knocked down in human umbilical vein endothelial cells (HUVECs). The expression of endothelial markers and mesenchymal markers was determined by real-time reverse transcription PCR (RT-PCR), immunofluorescence staining, and western blot analysis. Notch signaling pathway components were detected by real-time RT-PCR and western blot analysis. Cell mobility was evaluated by wound-healing, Transwell, and spreading assays. Fibroblast-specific protein 1 (FSP-1) promoter activity was determined by luciferase assay. Results: Transforming growth factor (TGF)-β1 treatment or integrin β3 overexpression significantly promoted the EndMT by downregulating VE-cadherin and CD31 and upregulating smooth muscle actin α and FSP-1 in HUVECs, and by enhancing cell migration. Knockdown of integrin β3 reversed these effects. Notch signaling was activated after TGF-β1 treatment of HUVECs. Knockdown of integrin β3 suppressed TGF-β1-induced Notch activation and expression of the Notch downstream target FSP-1. Conclusion: Integrin β3 may promote the EndMT in HUVECs through activation of the Notch signaling pathway

Non-nested time series model selection, testing and application to exchange rate models

This dissertation considers choice criteria and test statistics for non-nested time series regression models that are stationary or non-stationary. The non-nestedness of models includes differences in linear parameter restrictions, and models are estimated by the IV method. The choice criterion proposed for non-nested stationary models is asymptotically valid in probability. This choice criterion is also asymptotically valid for non-nested non-stationary models, but only in distribution. Incorporating the correct linear constraints can enhance the selection of rival models. The test statistic proposed for non-nested stationary models has an asymptotically standard normal distribution. It includes many existing tests as special cases. When models are nonstationary, the test statistic has an asymptotically standard normal distribution only under the very restrictive conditions that the disturbance terms are serially uncorrelated and uncorrelated with the first difference of regressors and instrument variables. This implies that the existing tests which are our special cases cannot be applied generally to non-nested non-stationary models. We construct a test with a non-parametric modification when the conditions are violated. When the test is valid for both stationary and non-stationary models, the consistency and the asymptotic power of the test under the local null are analyzed. The test is consistent if the true model is not nested within the alternative model at the true value of the parameter. The asymptotic power against the local null is higher for nonstationary models than for stationary models. In the stationary case, the computation of the test statistic can be implemented using several restricted OLS regressions. Monte Carlo simulation demonstrates that the testing procedure with the non-parametric modification performs very well in large samples. The empirical test of major competing exchange rate models indicates that the monetary model with flexible prices and different domestic and foreign demand for money functions performs best

Non-nested time series model selection, testing and application to exchange rate models

This dissertation considers choice criteria and test statistics for non-nested time series regression models that are stationary or non-stationary. The non-nestedness of models includes differences in linear parameter restrictions, and models are estimated by the IV method. The choice criterion proposed for non-nested stationary models is asymptotically valid in probability. This choice criterion is also asymptotically valid for non-nested non-stationary models, but only in distribution. Incorporating the correct linear constraints can enhance the selection of rival models. The test statistic proposed for non-nested stationary models has an asymptotically standard normal distribution. It includes many existing tests as special cases. When models are nonstationary, the test statistic has an asymptotically standard normal distribution only under the very restrictive conditions that the disturbance terms are serially uncorrelated and uncorrelated with the first difference of regressors and instrument variables. This implies that the existing tests which are our special cases cannot be applied generally to non-nested non-stationary models. We construct a test with a non-parametric modification when the conditions are violated. When the test is valid for both stationary and non-stationary models, the consistency and the asymptotic power of the test under the local null are analyzed. The test is consistent if the true model is not nested within the alternative model at the true value of the parameter. The asymptotic power against the local null is higher for nonstationary models than for stationary models. In the stationary case, the computation of the test statistic can be implemented using several restricted OLS regressions. Monte Carlo simulation demonstrates that the testing procedure with the non-parametric modification performs very well in large samples. The empirical test of major competing exchange rate models indicates that the monetary model with flexible prices and different domestic and foreign demand for money functions performs best

The Policy Impact of Carbon Emission Trading on Building Enterprises’ Total Factor Productivity in China

Nearly 40 percent of worldwide energy and process-related CO2 emissions are produced by the construction sector. China’s construction industry is the largest in the world, with Chinese construction enterprises completing a total output value of RMB 26.39 trillion in 2020; these buildings contribute to about 20 percent of China’s overall carbon emissions and 20 percent of the global total emissions. There is an urgent need to prove whether construction enterprises are benefiting from the carbon trading policy. Compared to the traditional method, a double difference model can be used to highlight the consequences of different states of construction enterprises’ responses to carbon trading regimes. In this study, we examine the following results based on cross-sectional data collected from 2006 to 2021, from listed construction enterprises: (1) Existing carbon emission policies have had a significant impact on the improvement of construction enterprises’ total factor productivity. This improvement is more pronounced in large state-owned enterprises in particular. (2) Construction enterprises’ greater involvement in carbon trading income is most strongly influenced by their green innovation level. (3) Construction enterprises located in eastern and central China benefit significantly from carbon trading, but construction enterprises based in the west do not. The research result indicates that future incentive initiatives should pay more attention to western regions and privately owned building enterprises. The leading role of large state-owned building enterprises should be reinforced

Petrogenesis of the Eocene Highly Fractionated Granite Porphyry with REE Tetrad Effect: An Example from Western Yunnan, Southeastern Tibetan Plateau

Highly fractionated granites are widely distributed in the crust and provide unique windows into magmatic evolution. This study reports petrography, zircon U–Pb ages, trace elemental, and Hf isotopic, as well as whole-rock elemental and Nd isotopic data of highly fractionated granite porphyries from the Shiguanshan area in western Yunnan, southeastern Tibet. The granite porphyries were formed at 34.0 ± 0.3 Ma in a post-collisional setting. They are strongly peraluminous (A/CNK = 1.95–2.80), have high SiO2 content (SiO2 = 78.16–79.13 wt.%) and zircon saturation temperatures (803–829 °C, average 819 °C), and low MgO, with pronounced enrichment in Pb, U, Th, and Rb, and depletion in Ti, Eu, P, Sr, and Ba, and belong to highly fractionated A-type granites. These rocks define linear trends on Harker diagrams and display similar enriched whole-rock Nd isotopic (εNd(t) = −12.8 to −12.3) and zircon Hf isotopic (εHf(t) = −10.4 to −8.8) compositions compared to the published data of coeval mantle-derived syenite porphyries, which can be attributed to fractional crystallization processes. A quantitative model suggests that the Shiguanshan granite porphyries likely formed through the fractionation process of a mineral assemblage consisting of plagioclase, K-feldspar, biotite, and amphibole (in a ratio of 40:30:25:5), with fractionation degrees of 50%–55%. The magmatic textures and zircons, decoupling between the REE tetrad effect and fractionation of twin-elements, along with the modeling result of Rayleigh fractionation, suggest that the REE tetrad effect in the Shiguanshan granite porphyries may be caused by fractionation of accessory minerals. Our data, along with regional observations, propose that the generation of these granite porphyries is possibly related to lithospheric removal following the Indo–Asia collision

Laterally Driven Resonant Pressure Sensor with Etched Silicon Dual Diaphragms and Combined Beams

A novel structure of the resonant pressure sensor is presented in this paper, which tactfully employs intercoupling between dual pressure-sensing diaphragms and a laterally driven resonant strain gauge. After the resonant pressure sensor principle is introduced, the coupling mechanism of the diaphragms and resonator is analyzed and the frequency equation of the resonator based on the triangle geometry theory is developed for this new coupling structure. The finite element (FE) simulation results match the theoretical analysis over the full scale of the device. This pressure sensor was first fabricated by dry/wet etching and thermal silicon bonding, followed by vacuum-packaging using anodic bonding technology. The test maximum error of the fabricated sensor is 0.0310%F.S. (full scale) in the range of 30 to 190 kPa, its pressure sensitivity is negative and exceeding 8 Hz/kPa, and its Q-factor reaches 20,000 after wafer vacuum-packaging. A novel resonant pressure sensor with high accuracy is presented in this paper

Investigation of Unsteady Pressure Pulsations of Reactor Coolant Pump Passage under Flow Coast-down

In order to obtain the pressure pulsations of a reactor coolant pump during flow coast-down conditions, the time-domain characteristics of the flow passage under different times of flow coast-down were calculated by numerical calculation. Because the unsteady pressure pulsation signals in the RCP under flow coast-down are non-stationary and some phenomena may only occur in a short time, this paper analyzed them with the wavelet transform. The results show that the pressure fluctuation varies dramatically with the flow coast-down process and the variation rate of the pressure fluctuation coefficient can reach more than 60%. With the development of flow coast-down, there is a strong correlation between the pressure pulsation and number of impeller blades. The main frequency of the pressure pulsation gradually changes from high-frequency pulsation to low-frequency pulsation, and the regularity of the pressure pulsation is quickly destroyed, while the change in pressure pulsation regularity of the guide vane passage is more gentle than that of the impeller and pressurized water chamber. The change in wavelet intensity at the impeller outlet, guide vane inlet, and left side of the pressurized water chamber is more intense than at other areas