Practices on rockburst prevention and control in headrace tunnels of Jinping II hydropower station

AbstractRockburst problems induced by high in-situ stresses were prominent during construction of the headrace tunnels of Jinping II hydropower station. The rockbursts occurred in various forms, and it is necessary to take pertinent measures for integrated prevention and control of rockbursts. In view of the rockburst characteristics during tunnel construction of Jinping II hydropower station, the engineering geological conditions were presented, and the features, mechanisms and forms of rockbursts observed during construction were analyzed in detail. A large number of scientific researches, experiments and applications were conducted. Multiple measures were adopted to prevent and control rockbursts, including the prediction and early warning measures, stress relief by blasting in advance, optimized blasting design and optimized tunnel support in the tunnel sections prone to strong rockbursts. The effectiveness of these prevention and control measures was evaluated. Experiences have been accumulated through a great number of helpful explorations and practices for rockburst prevention and control. A comprehensive rockburst prevention and control system has been gradually established

AlignDet: Aligning Pre-training and Fine-tuning in Object Detection

The paradigm of large-scale pre-training followed by downstream fine-tuning has been widely employed in various object detection algorithms. In this paper, we reveal discrepancies in data, model, and task between the pre-training and fine-tuning procedure in existing practices, which implicitly limit the detector's performance, generalization ability, and convergence speed. To this end, we propose AlignDet, a unified pre-training framework that can be adapted to various existing detectors to alleviate the discrepancies. AlignDet decouples the pre-training process into two stages, i.e., image-domain and box-domain pre-training. The image-domain pre-training optimizes the detection backbone to capture holistic visual abstraction, and box-domain pre-training learns instance-level semantics and task-aware concepts to initialize the parts out of the backbone. By incorporating the self-supervised pre-trained backbones, we can pre-train all modules for various detectors in an unsupervised paradigm. As depicted in Figure 1, extensive experiments demonstrate that AlignDet can achieve significant improvements across diverse protocols, such as detection algorithm, model backbone, data setting, and training schedule. For example, AlignDet improves FCOS by 5.3 mAP, RetinaNet by 2.1 mAP, Faster R-CNN by 3.3 mAP, and DETR by 2.3 mAP under fewer epochs.Comment: Accepted by ICCV 2023. Code and Models are publicly available. Project Page: https://liming-ai.github.io/AlignDe

The perinatal period should be considered in neonatal acute respiratory distress syndrome: comparison of the Montreux definition vs. the second pediatric acute lung injury consensus conference definition

BackgroundThe recently developed Montreux definition for neonatal acute respiratory distress syndrome (ARDS) partially differs from the Second Pediatric Acute Lung Injury Consensus Conference (PALICC-2) definition. Here, we compare the Montreux and PALICC-2 definitions regarding morbidity, mortality, and prognosis of neonatal cases of ARDS in order to evaluate which definition is more appropriate for newborns.MethodsNeonates admitted to our neonatal intensive care unit between 1 January 2018 and 30 September 2019 who met the Montreux or PALICC-2 definition of neonatal ARDS were retrospectively analyzed (n = 472). One comparison was made between application of the Montreux and PALICC-2 definitions to neonates outside the perinatal period (> 7 d after birth). A second comparison was made between a diagnosis of neonatal ARDS within (≤ 7 d of birth) and outside (> 7 d after birth) the perinatal period using the Montreux definition.ResultsNo significant differences in morbidity, mortality, severity, therapies, or prognosis were observed between neonates in the extra perinatal group according to the Montreux and PALICC-2 definitions. However, epidemiology, clinical course, and prognosis of neonatal ARDS within the perinatal period did differ from those outside the perinatal period according to the Montreux definition.ConclusionNeonates with ARDS within the perinatal period have unique triggers, epidemiology, clinical course, and prognosis, yet a similar pathobiology pattern, to neonates at other ages. Therefore, it may be essential to consider the perinatal period when defining neonatal ARDS

Low-mass dark matter search results from full exposure of PandaX-I experiment

We report the results of a weakly-interacting massive particle (WIMP) dark matter search using the full 80.1\;live-day exposure of the first stage of the PandaX experiment (PandaX-I) located in the China Jin-Ping Underground Laboratory. The PandaX-I detector has been optimized for detecting low-mass WIMPs, achieving a photon detection efficiency of 9.6\%. With a fiducial liquid xenon target mass of 54.0\,kg, no significant excess event were found above the expected background. A profile likelihood analysis confirms our earlier finding that the PandaX-I data disfavor all positive low-mass WIMP signals reported in the literature under standard assumptions. A stringent bound on the low mass WIMP is set at WIMP mass below 10\,GeV/c$^2$, demonstrating that liquid xenon detectors can be competitive for low-mass WIMP searches.Comment: v3 as accepted by PRD. Minor update in the text in response to referee comments. Separating Fig. 11(a) and (b) into Fig. 11 and Fig. 12. Legend tweak in Fig. 9(b) and 9(c) as suggested by referee, as well as a missing legend for CRESST-II legend in Fig. 12 (now Fig. 13). Same version as submitted to PR

The Research Value of Biphasic Registration Quantitative Computed Tomography Emphysema Index in the Evaluation of Mild to Moderate COPD

Objective: To find the optimal quantitative index of emphysema by comparing and analyzing the quantitative indexes of emphysema in patients with mild to moderate chronic obstruction pulmonary disease (COPD) via registered biphasic quantitative computed tomography (QCT). Methods: We retrospectively collected 55 healthy controls, 21 Global Initiative for Chronic Obstructive Pulmonary Disease (GOLD) 1 case, and 31 GOLD 2 cases in our hospital. We imported the CT raw DICOM data into the "Digital Lung" analysis platform and measured the LAA-950% at the end of deep inspiration and the LAA-910% at the end of deep expiration. The expiratory and inspiratory CT images were registered. Then, the percentage of emphysema area (PRMEmph%), the percentage of functional small airway disease area (PRMfSAD%), and the percentage of the normal area (PRMNormal%) were calculated according to the threshold method. Pulmonary function indicators included FVC, FEV1%, and FEV1/FVC. Differences in general data, CT quantitative indexes, and pulmonary function between groups were assessed using the independent sample t-test, Mann–Whitney U test, or chi-square test, and the correlation was analyzed using Spearman correlation. The receiver operating characteristic (ROC) curve was drawn to analyze the diagnostic performance of CT quantitative parameters for emphysema in patients with mild to moderate COPD. Results: There were significant differences in sex, smoking index, FEV1%, FEV1/FVC, inspiratory phase LAA%-950, expiratory phase LAA%-910, PRMEmph%, PRMfSAD%, and PRMNormal% between the mild to moderate COPD patients and normal control groups. The inspiratory phase LAA%-950 was negatively correlated with FEV1/FVC, the expiratory phase LAA%-910 and PRMEmph% were negatively correlated with FVC, FEV1%, and FEV1/FVC. ROC curve analysis results showed that the areas under the curve of inspiration phase LAA%-950, expiratory phase LAA%-910, and PRMEmph% were 0.742, 0.861, and 0.876, respectively. Among them, the area under the curve of the PRMEmph% index was the largest, with a corresponding critical value of 9.84%, a sensitivity of 76.90%, and a specificity of 94.50%. Conclusion: Quantitative CT emphysema index LAA%-950 in the inspiratory phase, LAA%-910 in the expiratory phase, and PRMEmph% in biphasic can objectively evaluate emphysema in patients with mild to moderate COPD, among which PRMEmph% is the best evaluation index