The polymer solution flow in porous media is a central research topic related to hydraulic fracturing measures, formation damage and fracture propagation. Influenced by molecular weights and ...concentrations, various flow patterns of polymer in pores are presented, resulting in different filtration loss. In this work, the effectiveness of various polymer solutions for filtration loss was assessed by utilizing the core flooding experiment firstly. The result shows that lesser filtration loss normally is inextricably linked to solutions with high molecular weight and concentration. Subsequently, the flow behaviors of polymer solutions investigated by designed micro pore-throat structure and micro-particle image velocimetry (μ-PIV) further confirmed the above result. It was found that the central convergent flow pattern benefiting from higher viscous force loss and less filtration loss was observed at high flow rates (0.5 mL/h), and higher molecular weight and concentration were more prone to convergent flow patterns. The viscosity force loss increases by about 4 times varying the molecular weight of polymer from 5 × 106 to 18 × 106 g/mol or the concentration from 0.05 to 0.3%. It interprets higher molecular weight and concentration in core studies and field observations with decreased filtration loss of HPAM. This work provides a theoretical foundation for the application of fracturing fluids as well as fresh perspectives on how to access the filtration loss of fracturing fluids.
Surveillance and monitoring systems generally employ a large number of cameras to capture people's activities in the environment. These activities are analyzed by hosts (human operators and/or ...computers) for threat detection. Threat detection is a target centric task in which the behavior of each target is analyzed separately, which requires a significant amount of human attention and is a computationally intensive task for automatic analysis. In order to meet the real-time requirements of surveillance, it is necessary to distribute the video processing load over multiple hosts. In general, cameras are statically assigned to the hosts; we show that this is not a desirable solution as the workload for a particular camera may vary over time depending on the number of targets in its view. In the future, this uneven distribution of workload will become more critical as the sensing infrastructures are being deployed on the cloud. In this paper, we model the camera workload as a function of the number of targets, and use that to dynamically assign video feeds to the hosts. Experimental results show that the proposed model successfully captures the variability of the workload, and that the dynamic workload assignment provides better results than a static assignment.
Hospital Acquired Pneumonia (HAP) is one of the most common complications and late causes of death in TBI patients. Targeted prevention and treatment of HAP are of great significance for improving ...the prognosis of TBI patients. In the previous clinical observation, we found that folic acid treatment for TBI patients has a good effect on preventing and treating HAP. We conducted this retrospective cohort study to demonstrate what we observed by selecting 293 TBI patients from two medical centers and analyzing their hospitalization data. The result showed that the incidence of HAP was significantly lower in TBI patients who received folic acid treatment (44.1% vs. 63.0%,
= 0.012). Multivariate logistic regression analysis showed that folic acid treatment was an independent protective factor for the occurrence of HAP in TBI patients (OR = 0.418,
= 0.031), especially in high-risk groups of HAP, such as the old (OR: 1.356 vs. 2.889), ICU (OR: 1.775 vs. 5.996) and severe TBI (OR: 0.975 vs. 5.424) patients. At the same time, cohort studies of HAP patients showed that folic acid also had a good effect on delaying the progression of HAP, such as reducing the chance of tracheotomy (26.1% vs. 50.8%,
= 0.041), and reduced the length of hospital stay (15 d vs. 19 d,
= 0.029) and ICU stay (5 d vs. 8 d,
= 0.046). Therefore, we believe that folic acid treatment in TBI patients has the potential for preventing and treating HAP, and it is worthy of further clinical research.
Abstract
The High-density Polyethylene/Ethylene Propylene Diene Monomer/Graphite Fluoride (HDPE/EPDM/GF) composites are prepared by dynamic vulcanization technology. The composites with sea-island ...structure which contributes to excellent mechanical properties can be easily recycled and re-thermoplasticized. A unique processing technology is designed to make graphite fluoride distributed on the phase interface of the material. The prepared phase interface with aggregated GF has very low interfacial energy, and this unique phase interface greatly improves the hydrophobicity of the material. The static WCA reaches 153° with a WSA 12° for composite containing 15 phr graphite fluoride. What’s more, the composite material has relatively good wear resistance, and when the surface of the composite material is damaged, the composite material can still maintain excellent hydrophobicity. Therefore, the superhydrophobic material prepared by this convenient method can be used for potential industrial application.
In this paper, we present an RFID based human and Unmanned Aerial Vehicle (UAV) Interaction system, termed RFHUI, to provide an intuitive and easy-to-operate method to navigate a UAV in an indoor ...environment. It relies on the passive Radio-Frequency IDentification (RFID) technology to precisely track the pose of a handheld controller, and then transfer the pose information to navigate the UAV. A prototype of the handheld controller is created by attaching three or more Ultra High Frequency (UHF) RFID tags to a board. A Commercial Off-The-Shelf (COTS) RFID reader with multiple antennas is deployed to collect the observations of the tags. First, the precise positions of all the tags can be obtained by our proposed method, which leverages a Bayesian filter and Channel State Information (CSI) phase measurements collected from the RFID reader. Second, we introduce a Singular Value Decomposition (SVD) based approach to obtain a 6-DoF (Degrees of Freedom) pose of the controller from estimated positions of the tags. Furthermore, the pose of the controller can be precisely tracked in a real-time manner, while the user moves the controller. Finally, control commands will be generated from the controller's pose and sent to the UAV for navigation. The performance of the RFHUI is evaluated by several experiments. The results show that it provides precise poses with 0.045 m mean error in position and 2.5∘ mean error in orientation for the controller, and enables the controller to precisely and intuitively navigate the UAV in an indoor environment.
Circular RNAs (circRNAs) have emerged as important roles in various inflammatory processes of rheumatic diseases. However, their expression profiles and influences in the pathogenesis of ankylosing ...spondylitis (AS) remain unclear. In this study, we revealed the differential expression profiles of circRNAs in peripheral blood mononuclear cells (PBMCs) in AS by circRNA sequencing. We screened the differentially expressed circRNAs in AS and verified that hsa_circ_0000652 was upregulated and had potential to be a biomarker of progression. Functionally, hsa_circ_0000652 promoted proliferation and cytokine production in macrophages and inhibited apoptosis. Through dual-luciferase assays and RNA pull-down assays, we demonstrated that hsa_circ_0000652 acted as a competing endogenous RNA (ceRNA) by binding with hsa-miR-1179 and regulated OX40L, which is characterized as a co-stimulatory molecule and found to be upregulated in AS patients. As a result, hsa_circ_0000652 aggravated the inflammation in the coculture system containing CD4
T cells and macrophages via OX40/OX40L interaction. Our findings suggest that hsa_circ_0000652 was upregulated in AS patients and may serve as a pro-inflammatory factor in macrophages and a positive regulator of OX40/OX40L by sponging hsa-miR-1179.
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•Carbon spheres (CSs) supported NZVI were innovatively synthesized via liquid phase reduction method.•NZVI/CSs composite exhibited enhanced dispersion and activity.•The degradation ...mechanism of MNZ by NZVI/CSs was investigated with a revised kinetic model.•Micro galvanic cells between NZVI and CSs were essential for MNZ adsorption and reduction.
For the first time, carbon spheres-supported nanoscale zero-valent iron (NZVI/CSs) were successfully synthesized as functionalized composite via liquid phase reduction method and adopted for removal of a typical antibiotic, metronidazole (MNZ), from wastewater. The resultant composite (NZVI/CSs) exhibit higher reactivity, excellent stability, enhanced dispersion, and improved longevity over the reaction course due to the presence of the charged carboxyl groups and hydroxyl groups on the surfaces of CSs. The results show that 94.18% of MNZ was removed using NZVI/CSs after 6min, while only 36.45% and 8.78% of MNZ were removed using NZVI and CSs, respectively. The galvanic cell system between NZVI and CSs was essential for enhancing MNZ reduction in aqueous solution. Furthermore, the new findings include kinetics for MNZ removal by NZVI/CSs composite could be well expressed by a revised two-parameter pseudo-first-order model. Finally, the possible degradation mechanism was proposed, which was based on the analysis of degraded products by high performance liquid chromatography–mass spectrometry (HPLC–MS). Different important factors impacting on MNZ removal (including mass ratio of NZVI to CSs, initial concentration, pH value and solution temperature) were investigated as well. Overall, this study provides a promising alternative material and environmental pollution management option for antibiotic wastewater treatment.
Soil salinization has become a major environmental factor severely threatening global food security. The application of porous minerals could significantly ameliorate soil fertility and promote plant ...productivity under salt stress conditions. However, the effects of porous minerals on improving the salt resistance of grain crops in coastal saline soils is not fully studied. In this work, the shoot growth and grain yield of wheat plants grown in coastal saline fields, respectively amended with the four naturally available porous minerals, diatomite, montmorillonite, bentonite and zeolite, were assessed. The application of porous minerals, especially zeolite, significantly improved the biomass and grain yield of wheat plants under saline conditions, as demonstrated by the augmented plant fresh mass (14.8~61.2%) and increased seed size (3.8~58.8%) and number (1.4~57.5%). Soil property analyses exhibited that porous-mineral amendment decreased soil sodium content and sodium absorption ratio, and increased soil nutrients in both the rhizosphere and nonrhizosphere of wheat plants. Further quantitative-PCR and 16S high-throughput sequencing analysis revealed that porous-mineral application also remarkably increased the abundance of bacterial 16S rRNA (0.8~102.4%) and fungal 18S rRNA (89.2~209.6%), and altered the composition of the soil microbial community in the rhizosphere of wheat. Our findings suggest that zeolite could be used as an ideal salt soil amendment, and the changes in soil properties and microorganisms caused by the application of porous minerals like zeolite improved the salt resistance of wheat plants in coastal saline land, leading to increased shoot growth and seed production.
The direct shear test is implemented in this paper for infilled joints under constant normal stiffness (CNS) condition with the finite difference software FLAC3D. The CNS condition was performed ...based on a servoprogram developed by FISH language. The effects of initial normal stress, undulating angle, and infilled ratio on the shear failure mode of infilled joints under CNS are revealed based on numerical simulation. It is found that the shear strength of infilled joints will grow along with the increase of the undulating angle and the decrease of the infilled ratio. The numerical analysis method is also able to quantify the effect of multiple factors (initial normal stress and infilled ratio) on shear properties of infilled joints. The model shows a good agreement with the experimental results available in the literatures. Therefore, this study proposed and verified a numerical analysis method capable of studying the effects of normal stress, undulating angles, and infilled ratio on the shear behavior of infilled rock joints.
The all-electric subsea gate valve actuator is one of the critical components of the all-electric subsea production control system. To bridge the gap of the low-power holding mechanism in the ...all-electric subsea gate valve actuator of the subsea production system, minimize the power consumption and cable number for control and improve the open-position keeping performance of all-electric subsea gate valve actuator, this paper proposed a novel low-power holding mechanism for the all-electric subsea gate valve actuator which can be applied to all-electric subsea gate valve actuators with various valve sizes and process pressure ratings. The proposed low-power holding mechanism uses an electromagnet as a driving element, combines the spiral transmission and the cam-like transmission, and only requires a holding force of approximately 2–7% of the maximum load of the closing spring to keep the valve open. The proposed low-power holding mechanism converts the axial force of the closing spring into the circumferential force, which substantially reduces the output force required for the driving element of the low-power holding mechanism and the number of the actuator’s control cables. Analytic models are created for the lockable maximum load of the closing spring and the permissible stroke of the locking tab with regard to the design variables. The parameter effects and the corresponding sensitivities are discussed by numerical analysis. The design parameters and the lockable maximum load of the closing spring of the low-power holding mechanism are obtained.
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