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Steam-assisted gravity oil drainage (SAGD flooding) is a cutting-edge technology for the development of oils which is gradually replacing steam huff and puff and is being used more and more widely. Low-permeability interlayers are generally developed in oil reservoirs in China, which may shield the migration of steam, oil and gas. Targeted acidizing fracturing was proposed to break through the low-permeability interlayers, and hence, the problem that the hindrance to the expansion of the steam chamber led to heat loss and seriously affected the development effect could be solved. A typical kind of well with SAGD flooding actually applied in China, Shuyi District of Liaohe Oilfield, was taken as the example for studying the optimization of crack parameters. Based on the study of reservoir sensitivity characteristics in this well, the formulations of working fluids for targeted acidizing fracturing were developed by optimizing the weight percentages of main acid solution and additives. The formula of '4% hydrochloric acid + 2% polyphosphoric acid + 5% fluoroboric acid + 4% acetic acid' could be used as the acidizing fracturing working fluid for typical blocks of the Shuyi District of Liaohe Oilfield, which can increase the permeability of the natural core by 40.19–57.06%. Studies on targeted acidizing fracturing are beneficial for enhancing the oil recovery of oil reservoirs. [ABSTRACT FROM AUTHOR]

• Theoretically formulated a hedging function consistent with the Budyko framework. • The derived function outperforms commonly-used rules. • The derived function depicts a general non-linear "supply–demand" relationship. Operating rules play an important role in enhancing the water utilization of reservoirs. Previous studies on hedging investigated the operating rules between water release (R) and available water (AW) based on minimizing the normalized shortage index, and applied the rules to optimization. However, seldom considered a realistic economic objective function to form a more general "supply–demand" relationship. To address this issue, this study formulated a theoretical function by a two-period reservoir operation model with the goal of minimizing the sum of economic loss from the current release and carryover storage targets. The derived function that guides the water supply was numerically validated to obtain the optimal time-varying hedging rules by non-dominated sorting genetic algorithm Ⅱ. The water-supply system of Dongwushi Reservoir in Hebei Province, China was selected as a case study. The results show that (1) The derived function depicts the relationship between "R-AW ratio" and "D-AW ratio", which is consistent with the Budyko "supply–demand" framework. (2) The optimized results using the derived Budyko hedging function outperform those using two-point hedging rule (TPH) and standard operating policy (SOP). (3) The derived function depicts a general non-linear "supply–demand" relationship rather than the linear one contained in commonly-used TPH. The derived function could be used for varied demands, indicating broader applications than TPH. [ABSTRACT FROM AUTHOR]

Reservoirs lined with concrete slabs are very common in the northern cold regions of China. Failures such as the rotation and the dislocation of concrete lining slabs are usually found in those ice-covered reservoirs each year in winter. In this study, the interaction processes between water, ice, and lining when water level changes in ice-covered reservoirs are evaluated based on the theory of beams on elastic foundation. In general, ice cover can generate a rotation effect (bending moment) on concrete lining slabs when water level changes in ice-covered reservoirs. Under such conditions, the bending moment at the ice edge increases with the increase of the ice cover width and thickness. Once the tensile stress at the interface between concrete slab and its base layer exceeds the tensile strength of the interface itself, the concrete slab separates from its base layer and the support condition of the ice cover changes from fix-supported to hinge-supported. Then the rotational failure of the concrete slab may occur due to the rotation effect acted by ice cover. The calculated rotation angle of the concrete lining slab is in agreement with the angle observed at a reservoir in northwest China. In addition, prevention measures such as concrete lining slabs with hydrophobic coating on the surface, concrete lining slabs with dark surface, anchoring concrete slabs to reservoir slope, and integral large-scale lining modules are proposed to mitigate such rotational lining failures in ice-covered reservoirs. The results can help to improve the performance and service life of reservoirs in cold environments. [ABSTRACT FROM AUTHOR]

[Display omitted] • Integrated design of green and grey infrastructure with real-time control rules. • System failures were considered while optimizing the renovation scheme. • More investment does not necessarily increase system resilience to failures. • Resilience to failures significantly increased while maintaining other objectives. The mutual benefits of real-time control and green and grey infrastructure for urban drainage system (UDS) renovations have drawn great attention. However, risks emerged due to equipment and structural failures, and no studies considered such failures while optimizing the renovation scheme. To address this issue, this study proposed a multi-criteria optimization method for the integrated design of green and grey infrastructure with real-time control rules, where the economic cost and system performance under normal and exceptional conditions were optimized simultaneously. Failure probabilities of equipment and structure were quantified using homogeneous Poisson process models, and failure losses were estimated with the aid of a machine learning-based surrogate model. This approach was tested with a combined UDS in China. Results indicate that: (1) More investment does not necessarily increase system resilience to failures. Equipment and structural failures can significantly lower the effectiveness of grey infrastructure and real-time control. Therefore, solutions with more investments in grey infrastructure, which indicate higher costs, experience greater failure losses. (2) System resilience to failures can be significantly improved while maintaining other objectives when compared with the traditional design scheme. The proposed method allows for a new perspective in addition to the cost-and-resilience two-objectives design of UDS renovations, especially for systems threatened by various failures. [ABSTRACT FROM AUTHOR]

• A trade-driven model of "Hydropower for Rice" cooperation was established. • "Hydropower for Rice" cooperation is feasible. • Dominant factors are rice trade of downstream countries and China's reservoir operation. There have been intense conflicts over water resources between upstream and downstream countries in the Lancang-Mekong River Basin (LMRB) over the past years, primarily due to the trade-off relationship between hydropower and rice production. Great potential for transboundary cooperation has been shown, such as China's emergency water release in 2016 to alleviate downstream severe drought. However, there is still a lack of systematic cooperation pattern. To address this issue, the study proposes a trade-driven model of "Hydropower for Rice" cooperation, and then derives three key political factors including price weight, export rate, and terminal water level of reservoirs. Our results show that (1) The hydropower and rice production under the trade-driven model can approximate the centralized model, and the "Hydropower for Rice" cooperation is feasible. (2) For downstream countries, rice is the main product, and the rice production and economic benefit can be increased with a higher price weight or export rate. Compared to Thailand and Cambodia, Vietnam needs to engage in deeper trade with China. (3) For upstream China, hydropower is the main product, and the economic benefit of riparian countries can be increased with higher export rates. The discharge in the dry season is increased, which is driven by the trade of rice. Additionally, China's initiative to reduce the terminal water level of reservoir Nuozhadu has the potential to further increase rice production in downstream countries. This study indicates that the transboundary cooperation in LMRB requires joint efforts of upstream and downstream countries. [ABSTRACT FROM AUTHOR]

Quantifying the uncertainty of stormwater inflow is critical for improving the resilience of urban drainage systems (UDSs). However, the high computational complexity and time consumption obstruct the implementation of uncertainty-addressing methods for real-time control of UDSs. To address this issue, this study developed a machine learning-based surrogate model (MLSM) that maintains high-fidelity descriptions of drainage dynamics and meanwhile diminishes the computational complexity. With stormwater inflow and controls as inputs and system overflow as the output, MLSM is able to fast evaluate system performance, and therefore stochastic optimization becomes feasible. Thus, a real-time control strategy was built by combining MLSM with the stochastic model predictive control. This strategy used stochastic stormwater inflow scenarios as input and aimed to minimize the expected overflow under all scenarios. An ensemble of stormwater inflow scenarios was generated by assuming the forecast errors follow normal distributions. To downsize the ensemble, representative scenarios with their probabilities were selected using the simultaneous backward reduction method. The proposed control strategy was applied to a combined UDS of China. Results are as follows. (1) MLSM fit well with the original high-fidelity urban drainage model, while the computational time was reduced by 99.1%. (2) The proposed strategy consistently outperformed the classical deterministic model predictive control in both magnitude and duration dimensions of system resilience, when the consumed time compatible is with the real-time operation. It is indicated that the proposed control strategy could be used to inform the real-time operation of complex UDSs and thus enhance system resilience to uncertainty. • Machine learning-based surrogate model (MLSM) replaced high-fidelity process model. • Stochastic model predictive control (MPC) became feasible with MLSM. • MLSM reduced computational time significantly without compromising MPC efficacy. • Stochastic MPC based on MLSM achieved more resilience than deterministic one. [ABSTRACT FROM AUTHOR]

The medical grid including hospitals at all levels is a new hierarchical diagnosis and treatment system. It is assumed to provide health services for residents in a certain area, allowing free referral of patients, so as to effectively utilize medical resources. Therefore, from the perspective of the government, the key issue is how to divide the medical grid in a robust and balanced manner. In this paper, various deterministic factors, such as hospital level, location and department, as well as uncertain factors, including patient distribution or population density, are considered in decision-making. To solve this problem, a dual-clustering algorithm based on K-means and K-medoids (DCKK) is developed with local search methods to minimize the average patient waiting and travelling time. The experimental results show that DCKK algorithm can generate better and more robust grid partition solutions than the existing mainstream algorithms in different scenarios. In addition, the rules between the number of medical grids and the number of patients, as well as the hospital sharing between medical grids, are also studied. Finally, a real medical grid partition case of Ji'nan, China, with forty hospitals in four urban areas, is studied, and five medical grids are recommended. • Develop a robust dual-clustering algorithm associated with six local search methods for medical grid partition. • Patient referral can improve the utilization of medical resources and shorten the patients' waiting and travelling time. • Investigate the law between the number of medical grids and the number of patients. • The sharing and marginal hospitals from different grids can significantly reduce patient waiting and travelling time. [ABSTRACT FROM AUTHOR]

• Temporal sensitivity for hydrological processes enhances identifiability of process structure. • Quickflow and soil evaporation are more easily identified than infiltration, baseflow, and snow balance. • The model identified by sensitivity-weighted MAE outperforms that by MAE without sensitivity-weights. Structure identifiability of hydrological processes refers to the ability to select appropriate mathematical representation from multiple structural options. Although the influence of hydrological processes on model behavior varies in time, this temporal relative influence has not been used to identify process structures. In this work, a framework is proposed to investigate the impacts of temporal relative influence of hydrological processes on structure identification. The framework consists of four elements: (1) a blended model, where hydrological process options and parameter values are regarded as integer and continuous decision variables, respectively, is built based on the flexible modeling framework Raven; (2) the temporal sensitivities of each process are derived by using Sobol' sensitivity analysis on a moving window; (3) performance metrics with and without sensitivity-weights, which are derived from the temporal sensitivities, are used to identify process structures, respectively; and (4) models identified by these two methods are compared to evaluate performance. A synthetic experiment is designed to validate the proposed framework. Three case studies are carried out in the Tongtianhe, Xunhe, and Wudinghe basins in China. Results are summarized as follows: (1) sensitivity-weighted performance metrics improve the identifiability of process structures by considering the temporal relative influence of hydrological processes on model behavior; (2) quickflow and soil evaporation processes are the two most identifiable processes, followed by infiltration, baseflow, and snow balance processes; and (3) the model identified by sensitivity-weighted performance metrics is more efficient than that selected by the performance metric without sensitivity-weights. It is recommended that the temporal sensitivity of hydrological processes be used to identify model structures based on flexible modeling frameworks. [ABSTRACT FROM AUTHOR]

Aeolian sand is sometimes used as geomaterial in cold regions of China. This paper tries to investigate the unfrozen water, matric suction of aeolian sand, which is related to its thermal and mechanical properties. The pF-meter matric suction sensor coupled with 5TM moisture content sensor that can operate in the subfreezing environment was used to measure the moisture content and matric suction of aeolian sand under different conditions. Combined with thermal resistor temperature probe, the relationship between unfrozen water and temperature is analyzed. The results indicate a significant phenomenon of latent heat absorption and release at freezing and thawing points. In addition, the phenomenon of the supercooling was observed with a value of −1.96 °C during stepwise temperature change. Most water in the sand freezes at freezing point 0 °C under rapid and stepwise temperature change. There is approximately 3% of unfrozen water content retained when the sand temperature drops to −15 °C. The soil matric suction increases very slowly at the stable freezing stage. These results provide the theoretical support for future research on the moisture migration mechanism and engineering application of aeolian sand in cold regions. • Matric suction and unfrozen water of aeolian sand were studied. • Most water in aeolian sand freezes at freezing point 0 °C. • Significant supercooling effect was observed under the rapid freezing process. • Matric suction shows dramatic change at freezing and thawing points. [ABSTRACT FROM AUTHOR]

Purpose: The Fremantle back awareness questionnaire (FreBAQ) was recently developed as simple and quick tool to assess back-specific body perception in Low back pain (LBP) patients. The aim of the present study was to translate and cross-culturally adapt the Fremantle back awareness questionnaire (FreBAQ) into a Simplified Chinese version (FreBAQ-C), and evaluate the reliability and validity of the FreBAQ-C in patients with non-specific Chronic Low back pain (CLBP)., Methods: The FreBAQ was translated into Chinese according to established methods. Internal consistency was assessed according to Cronbach's alpha. Test-retest reliability was estimated by Intraclass correlation coefficient (ICC). Construct validity was evaluated by correlations between the FreBAQ-C and Visual analogue scale (VAS), Roland-Morris disability questionnaire (RDQ), Pain catastrophizing scale (PCS), Tampa scale for kinesiophobia (TSK) as well as Hospital anxiety and depression scale (HADS)., Results: A total of 105 participants (38 males and 67 females) were included in this study with the mean age of 54.1 ± 15.6 years, mean duration of LBP of 6.8 ± 4.6 years. The FreBAQ-C total scores were well distributed, with no floor or ceiling effects. Internal consistency was excellent (Cronbach's alpha = 0.833). ICC of test-retest reliability was good (0.897, 95% confidence interval: 0.852-0.929). The limits of agreement (LOA) ranged from - 5.8 to 6.3. The Standard error of measurement (SEM) and Minimum detectable change (MDC) were 2.16 and 5.99. Construct validity was confirmed by significant correlation of The FreBAQ-C and VAS during motion (r = 0.274, p = 0.005) and rest (r = 0.243, p = 0.012), RDQ (r = 0.377, p < 0.001), PCS (r = 0.439, p < 0.001), and TSK(r = 0.311, p = 0.001)., Conclusions: The FreBAQ-C was demonstrated to have acceptable reliability and validity for patients with non-specific CLBP in Chinese mainland. It will allow evaluating body preception of the back in the Chinese population with CLBP., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The Chinese space station will be built around 2020. As a national space laboratory, it will offer unique opportunities for studying the physiological effects of weightlessness and the efficacy of the countermeasures against such effects. In this paper, we described the development of countermeasure systems in the Chinese space program. To emphasize the need of the Chinese space program to implement its own program for developing countermeasures, we reviewed the literature on the negative physiological effects of weightlessness, the challenges of completing missions, the development of countermeasure devices, the establishment of countermeasure programs, and the efficacy of the countermeasure techniques in American and Russian manned spaceflights. In addition, a brief overview was provided on the Chinese research and development on countermeasures to discuss the current status and goals of the development of countermeasures against physiological problems associated with weightlessness.

Cerebrotendinous xanthomatosis (CTX) is an autosomal recessive, lipid storage disorder which is extremely rare in the Chinese population. It is characterized by progressive neurologic dysfunction and enlargement of tendon xanthomas, and is often accompanied with neuropsychiatric symptoms. Few reports are available regarding depression and antidepressant medication in CTX patients. Here, we report a Chinese case of CTX associated with fluoxetine-responsive major depression., (Copyright © 2012 Elsevier Inc. All rights reserved.)