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"Flushing"
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A Novel In-Seam Borehole Discontinuous Hydraulic Flushing Technology in the Driving Face of Soft Coal Seams: Enhanced Gas Extraction Mechanism and Field Application
Soft coal seams are characterized by high gas content, high tectonic stress, low strength, and low permeability; thus, gas extraction from soft coal seams is rather difficult, and outburst accidents commonly occur in their driving face. To enhance gas extraction and thus prevent outburst disasters, a novel in-seam borehole discontinuous hydraulic flushing (ISBDHF) technology was proposed in this work. By adopting a multiphysical coupling model and a new FLAC3D and COMSOL Multiphysics combined numerical solving method, we first analyzed the enhanced gas extraction mechanism of hydraulic flushing using the numerical simulation method. After that, this new technology was applied in the Xinjing coal mine, and its application results were systematically investigated. The numerical simulation results showed that the generation of new fractures in the plastic failure zone caused by hydraulic flushing could not only increase the coal permeability by 2–3 orders of magnitude, but also decrease its gas sorption time from 1 day to several minutes due to the decrease in matrix size. Therefore, hydraulic flushing enhances gas extraction by the combined effect of increasing permeability and increasing diffusion. Moreover, nearby flushing cavities may interact with each other under multicavity conditions, further improving the permeability-increasing and diffusion-increasing effects. After adopting ISBDHF technology in the Xinjing coal mine, the borehole number and gas extraction period in the driving face decreased by 73.5 and 77.8%, respectively, while the gas extraction rate increased from 28.20 to 34.35%, which improved the coal roadway excavation speed by 1.37 times.
Journal Article
Local flushing timescales in the flow separation zone of a T-shaped open-channel confluence
To acquire knowledge of the surface storage effects in the flow separation zone of a T-shaped open-channel confluence, independent Large Eddy Simulations are performed of the flushing with fresh water of a downstream branch which is initially uniformly contaminated by a passive scalar. Based on the ensemble averaged concentration, the spatial distributions of the local flushing lag and the local flushing time are determined. The flushing lag is much smaller than the flushing time, except in the maximum velocity zone, where both timescales are of the same small magnitude. For the local flushing time, the separation zone shear layer forms a transition between the high values in the flow separation zone and the low values in the maximum velocity zone. Inside the separation zone, the highest flushing times occur in a small zone near the downstream junction corner. Delineations in the time-averaged velocity field of the separation zone or its proxies, the recirculation zone and the reverse flow zone, are also assessed as pragmatic means to find the zone with the highest local flushing times. Finally, a regional flushing time and a residence time distribution were also determined on the basis of performed simulations.
Journal Article
Effect of alcohol consumption on risk of hypertension based on alcohol-related facial flushing response: From the health examinees study
Alcohol consumption is a significant public health concern in Korea, with many individuals engaging in risky drinking behaviors. This study aims to analyze the association between facial flushing responses and the progression of hypertension in Korean adults, stratified by gender, using a large-scale prospective cohort study.
This study included 39,868 participants (10,868 males and 29,000 females) from the health examinees cohort. Participants were divided into two groups according to their weekly drinking patterns (moderate and heavy) and facial flushing responses (non-flusher and flusher) for statistical analysis. A multivariate Cox proportional hazards regression model was used to calculate hazard ratios and 95% confidence intervals between flushing response after alcohol consumption and hypertension risk.
In males, the flusher group with a moderate alcohol intake pattern had a decreased risk of incident hypertension compared with non-flushers. In females, the flusher group had relatively higher risk of pre-hypertension and hypertension compared to the non-flusher group.
The association between facial flushing and hypertension varies depending on the level of alcohol consumption and should be considered in relation to gender differences. Further research is needed to understand the relationship between facial flushing response and the risk of hypertension based on alcohol consumption levels.
•Alcohol consumption is a significant public health concern in Korea, with many individuals engaging in risky drinking behaviors.•In males, the flusher group with a moderate alcohol intake pattern had a decreased risk of incident hypertension compared with non-flushers.•The association between facial flushing and hypertension varies depending on the level of alcohol consumption and should be considered in relation to gender differences.
Journal Article
The Effects of Dripline Layout on Performance of Automatic Flushing Valve
【Objective】 The functions of drip-irrigation systems depend on many factors and in this paper, we investigated the performance of the automatic flushing valve as impacted by layout of dripline. 【Method】 The experiment compared four flushing valves which were manufactured by 3D printing. They were then fixed at the end of the 0.5 m Φ16PE pipe (C1), a 48 m dripline (C2), and two 48 m long driplines connected in parallel (C3), respectively. The changes in flushing duration (FD), flushing water volume (FQ), flushing velocity (FV) and the minimum inlet pressure of the driplines required for the flushing valve automatic closing (H1min) under different layouts were measured and compared. 【Result】 The flushing velocity of the single dripline in C2 and C3 decreased from 0.82~1.03 m/s to 0.34~0.66 m/s, and the difference between the dripline inlet pressure H1 and flushing valve inlet pressure H2 was in the range of 0.114~0.132 MPa and 0.047~0.088 MPa, respectively. Compared with C2, C1 and C3 reduced H1min by 74.8% and 40.4% on average, respectively. When FD or FQ was the same, H1 required for the four flushing valves varied in the order of C2 > C3 > C1. When H2 < 0.05 MPa, FD decreased by 999.75 s/MPa on average, while when H2 > 0.05 MPa, FD decreased slowly by 164.7 s/MPa on average. Regardless of the dripline layouts, FD and FQ are quadratic functions of H2. 【Conclusion】 The FD and FQ are related to H2, and independent of the dripline layouts. When H2 > 0.05 MPa, FD changes steadily and the flushing effect is uniform. Fixing the flushing valve at the end of multiple driplines in parallel reduces the system pressure for automatic closing of the flushing valve. However, further work is needed to test if the flushing performance meets the requirements in the field.
Journal Article
Numerical simulation study on gas drainage by interval hydraulic flushing in coal seam working face
In order to solve the problem of difficult gas extraction in coal mine, a method of gas extraction from coal seam by interval hydraulic flushing is put forward. Based on the coal seam gas occurrence conditions of 7609 working face in Wuyang Coal Mine, the numerical simulation research on gas drainage by ordinary drilling and hydraulic flushing drilling was carried out by using COMSOL numerical simulation software. The results show that with the increase of hydraulic flushing coal quantity, the effective gas drainage radius also increases. The effective extraction radius of ordinary drilling is 0.5 m, and the effective extraction radius is 1.0 m, 1.2 m and 1.3 m respectively when the coal flushing quantity is 0.5t/m, 1.0t/m and 1.5t/m. As multiple boreholes are drained at the same time, the boreholes will affect each other, which will reduce the gas pressure and increase the effective drainage radius, the spacing between boreholes can be greater than twice the effective drainage radius of a single borehole when arranging boreholes. And the smaller the flushing interval, the more uniform the gas pressure reduction area. According to the numerical simulation results, the ordinary drilling and 1.0t/m interval hydraulic flushing test were carried out in the field. Through observation and analysis, the gas concentration of the interval hydraulic flushing drilling module was increased by 31.2% and the drainage purity was increased by 5.77 times compared with the ordinary drilling module. It shows that the interval hydraulic flushing drilling can effectively improve the gas drainage effect.
Journal Article
Genetic influences on alcohol flushing in East Asian populations
Background
Although it is known that variation in the
aldehyde dehydrogenase 2
(
ALDH2
) gene family influences the East Asian alcohol flushing response, knowledge about other genetic variants that affect flushing symptoms is limited.
Methods
We performed a genome-wide association study meta-analysis and heritability analysis of alcohol flushing in 15,105 males of East Asian ancestry (Koreans and Chinese) to identify genetic associations with alcohol flushing. We also evaluated whether self-reported flushing can be used as an instrumental variable for alcohol intake.
Results
We identified variants in the region of
ALDH2
strongly associated with alcohol flushing, replicating previous studies conducted in East Asian populations. Additionally, we identified variants in the alcohol dehydrogenase 1B (
ADH1B
) gene region associated with alcohol flushing. Several novel variants were identified after adjustment for the lead variants (
ALDH2
-rs671 and
ADH1B
-rs1229984), which need to be confirmed in larger studies. The estimated SNP-heritability on the liability scale was 13% (S.E. = 4%) for flushing, but the heritability estimate decreased to 6% (S.E. = 4%) when the effects of the lead variants were controlled for. Genetic instrumentation of higher alcohol intake using these variants recapitulated known associations of alcohol intake with hypertension. Using self-reported alcohol flushing as an instrument gave a similar association pattern of higher alcohol intake and cardiovascular disease-related traits (e.g. stroke).
Conclusion
This study confirms that
ALDH2
-rs671 and
ADH1B
-rs1229984 are associated with alcohol flushing in East Asian populations. Our findings also suggest that self-reported alcohol flushing can be used as an instrumental variable in future studies of alcohol consumption.
Journal Article
The hydrodynamics of Lizard Island lagoon, Great Barrier Reef
Hydrodynamic processes are a major driver for marine systems, linking marine organisms with their environment. However, a lack of hydrodynamic data at an ecologically relevant spatial resolution has stymied our understanding of reef function, as exemplified by Lizard Island on the Great Barrier Reef. To address this gap, 23 to 27 Marotte HS current meters were deployed over three periods, collecting 15 months of current velocity data. Combining these data with wind and tide datasets, we provide a preliminary description of the circulation in the Lizard Island lagoon, examining wind and tide influence, and flushing time. During south-easterly trade winds, flood tides flow through the Lagoon Entrance, while wind-induced waves cross the Bird-South crest, driving a north-westerly flow through Loomis Channel and across the western lagoon. Ebb tides flow east–south-east through the Lagoon Entrance and south-west through the Palfrey-South channel. Tides contribute a mean of 20.4% to the overall current speed, particularly in deeper sites with less reef interference, while shallow sites were more influenced by wind. Lizard Island lagoon flushing times ranged from a few hours to 10 days; longer during periods with low wind speeds. Hindcast flushing times during the 2016 coral bleaching event (following 8 Degree Heating Weeks) were approximately 22 h, suggesting that flushing time likely had minimal influence on bleaching. Our analyses provide initial insights into the circulation of the Lizard Island system and aid understanding of the potential relationships between reef organisms and their physical environment, bridging the gap between ecology and hydrodynamics.
Journal Article
Numerical study of effects of flushing gate height and sediment bed properties on cleaning efficiency in a simplified self-cleaning device
Sediment accumulation in combined sewers can induce blockage and odor problems. Among various cleaning methods, using self-cleaning device-generated flushing waves has been thought to be an effective solution. In this study, a series of numerical tests were conducted using CFD software to investigate the cleaning efficiency of deposited sediment particles based on a simplified self-cleaning device. The CFD model was validated by the experimental and numerical results in the literature. The effects of several parameters including the flushing gate height, sediment bed thickness, sediment bed length, and sediment bed position on cleaning efficiency were discussed. A relative accumulative transport rate was defined to analyze the cleaning efficiency. Results showed that the lowest height of the flushing gate had the best effects on sediment removal. The flushing waves generated from the sudden opening of the flushing gate were capable of cleaning sediment deposits in the given initial sediment bed thickness, length, and position. The required time duration for cleaning the sediment deposit completely increased about 6, 3, and 3 times when the sediment bed thickness, sediment bed length, and distance between the flushing gate and sediment bed increased 10, 4, and 7 times, respectively.
Journal Article
The Alcohol Flushing Response: An Unrecognized Risk Factor for Esophageal Cancer from Alcohol Consumption
Philip Brooks and colleagues discuss evidence linking the alcohol flushing response (predominantly due to ALDH2 deficiency) with a much higher risk of esophageal cancer from alcohol consumption.
Journal Article