Characterization of transient groundwater flow through a high arch dam foundation during reservoir impounding

AbstractEven though a large number of large-scale arch dams with height larger than 200 m have been built in the world, the transient groundwater flow behaviors and the seepage control effects in the dam foundations under difficult geological conditions are rarely reported. This paper presents a case study on the transient groundwater flow behaviors in the rock foundation of Jinping I double-curvature arch dam, the world's highest dam of this type to date that has been completed. Taking into account the geological settings at the site, an inverse modeling technique utilizing the time series measurements of both hydraulic head and discharge was adopted to back-calculate the permeability of the foundation rocks, which effectively improves the uniqueness and reliability of the inverse modeling results. The transient seepage flow in the dam foundation during the reservoir impounding was then modeled with a parabolic variational inequality (PVI) method. The distribution of pore water pressure, the amount of leakage, and the performance of the seepage control system in the dam foundation during the entire impounding process were finally illustrated with the numerical results

Experimental research on dynamic characteristics of a hybrid gas bearing-rotor system for high-speed permanent magnet machine

An experiment on the vibrational characteristics of a hybrid gas bearing-rotor system in a 45 kW high-speed permanent magnet machine test rig is conducted. Nonlinear methods of measurements and analyses, including bifurcation maps, frequency spectra, and axis orbits, are adopted to evaluate sub-synchronous vibration in rotor acceleration. The effects of bearing supply pressure and speed accelerating rates on the stability of the gas bearing-rotor system are determined. Experimental results show that half-speed whirling of the gas film is eliminated and the start of gas film whipping is delayed by using the appropriate bearing supply pressure plan, thereby improving stability. Meanwhile power frequency vibrational amplitude is the smallest during the acceleration process, including the critical speed, when the appropriate speed accelerating rates are employed

Context-I2W: Mapping Images to Context-dependent Words for Accurate Zero-Shot Composed Image Retrieval

Different from Composed Image Retrieval task that requires expensive labels for training task-specific models, Zero-Shot Composed Image Retrieval (ZS-CIR) involves diverse tasks with a broad range of visual content manipulation intent that could be related to domain, scene, object, and attribute. The key challenge for ZS-CIR tasks is to learn a more accurate image representation that has adaptive attention to the reference image for various manipulation descriptions. In this paper, we propose a novel context-dependent mapping network, named Context-I2W, for adaptively converting description-relevant Image information into a pseudo-word token composed of the description for accurate ZS-CIR. Specifically, an Intent View Selector first dynamically learns a rotation rule to map the identical image to a task-specific manipulation view. Then a Visual Target Extractor further captures local information covering the main targets in ZS-CIR tasks under the guidance of multiple learnable queries. The two complementary modules work together to map an image to a context-dependent pseudo-word token without extra supervision. Our model shows strong generalization ability on four ZS-CIR tasks, including domain conversion, object composition, object manipulation, and attribute manipulation. It obtains consistent and significant performance boosts ranging from 1.88% to 3.60% over the best methods and achieves new state-of-the-art results on ZS-CIR. Our code is available at https://github.com/Pter61/context_i2w

Identification of microRNA precursors based on random forest with network-level representation method of stem-loop structure

<p>Abstract</p> <p>Background</p> <p>MicroRNAs (miRNAs) play a key role in regulating various biological processes such as participating in the post-transcriptional pathway and affecting the stability and/or the translation of mRNA. Current methods have extracted feature information at different levels, among which the characteristic stem-loop structure makes the greatest contribution to the prediction of putative miRNA precursor (pre-miRNA). We find that none of these features alone is capable of identifying new pre-miRNA accurately.</p> <p>Results</p> <p>In the present work, a pre-miRNA stem-loop secondary structure is translated to a network, which provides a novel perspective for its structural analysis. Network parameters are used to construct prediction model, achieving an area under the receiver operating curves (AUC) value of 0.956. Moreover, by repeating the same method on two independent datasets, accuracies of 0.976 and 0.913 are achieved, respectively.</p> <p>Conclusions</p> <p>Network parameters effectively characterize pre-miRNA secondary structure, which improves our prediction model in both prediction ability and computation efficiency. Additionally, as a complement to feature extraction methods in previous studies, these multifaceted features can reflect natural properties of miRNAs and be used for comprehensive and systematic analysis on miRNA.</p

The effects of cognitive behavioural therapy on depression and quality of life in patients with maintenance haemodialysis: a systematic review

Depression is highly prevalent among Haemodialysis (HD) patients and is known to results in a series of adverse outcomes and poor quality of life (QoL). Although cognitive behavioural therapy (CBT) has been shown to improve depressive symptoms and QoL in other chronic illness, there is uncertainty in terms of the effectiveness of CBT in HD patients with depression or depressive symptoms. All randomised controlled trials relevant to the topic were retrieved from the following databases: CINHAL, MEDLINE, PubMed, PsycINFO and CENTRAL. The grey literature, specific journals, reference lists of included studies and trials registers website were also searched. Data was extracted or calculated from included studies that had measured depression and quality of life using valid and reliable tools -this included mean differences or standardised mean differences and 95% confidence intervals. The Cochrane risk of bias tool was used to identify the methodological quality of the included studies. Six RCTs were included with varying methodological quality. Meta-analysis was undertaken for 3 studies that employed the CBT versus usual care. All studies showed that the depressive symptoms significantly improved after the CBT. Furthermore, CBT was more effective than usual care (MD = - 5.28, 95%CI - 7.9 to - 2.65, P = 0.37) and counselling (MD = - 2.39, 95%CI - 3.49 to - 1.29), while less effective than sertraline (MD = 2.2, 95%CI 0.43 to 3.97) in alleviating depressive symptoms. Additionally, the CBT seems to have a beneficial effect in improving QoL when compared with usual care, while no significant difference was found in QoL score when compared CBT with sertraline. CBT may improve depressive symptoms and QoL in HD patients with comorbid depressive symptoms. However, more rigorous studies are needed in this field due to the small quantity and varied methodological quality in the identified studies

Synergistically enhance confined diffusion by continuum intersecting channels in zeolites

In separation and catalysis applications, adsorption and diffusion are normally considered mutually exclusive. That is, rapid diffusion is generally accompanied by weak adsorption and vice versa. In this work, we analyze the anomalous loading-dependent mechanism of p-xylene diffusion in a newly developed zeolite called SCM-15. The obtained results demonstrate that the unique system of “continuum intersecting channels” (i.e., channels made of fused cavities) plays a key role in the diffusion process for the molecule-selective pathways. At low pressure, the presence of strong adsorption sites and intersections that provide space for molecule rotation facilitates the diffusion of p-xylene along the Z direction. Upon increasing the molecular uptake, the adsorbates move faster along the X direction because of the effect of continuum intersections in reducing the diffusion barriers and thus maintaining the large diffusion coefficient of the diffusing compound. This mechanism synergistically improves the diffusion in zeolites with continuum intersecting channels.This work was supported by the National Natural Science Foundation of China (nos. 22032005, 21902180, 21802164, 21991092, 21991090, 22002174, and 91645112), the Natural Science Foundation of Hubei Province of China (2018CFA009), the Key Research Program of Frontier Sciences (CAS no. QYZDB-SSW-SLH026), Sinopec Corp. (417012-4), and the CAS Interdisciplinary Innovation Team (grant no. JCTD-2018-10). G.S. thanks the MICINN of Spain for funding through projects RTI2018-101784-B-I00, RTI2018-101033-B-I00, and SEV-2016-0683

Thermal resistance effect on anomalous diffusion of molecules under confinement

Diffusion is generally faster at higher temperatures. Here, a counterintuitive behavior is observed in that the movement of long-chain molecules slows as the temperature increases under confinement. This report confirms that this anomalous diffusion is caused by the “thermal resistance effect,” in which the diffusion resistance of linear-chain molecules is equivalent to that with branched-chain configurations at high temperature. It then restrains the molecular transportation in the nanoscale channels, as further confirmed by zero length column experiments. This work enriches our understanding of the anomalous diffusion family and provides fundamental insights into the mechanism inside confined systems.This work is supported by the National NaturalScience Foundation of China (22032005, 21902180, 21802164, 21991092,21991090, 22002174 and 91645112), and the Natural Science Foundation ofHubei Province of China (2018CFA009), the Key Research Program of FrontierSciences, Chinese Academy of Sciences (QYZDB-SSW-SLH026), and SinopecCorp. (417012-4). We are grateful to the Shenzhen Cloud Computing Centerfor their support in computing facilities.Peer reviewe