Stagnant Area Research Articles

Spatial and Temporal Distribution and Risk Assessment of Heavy Metals in Surface Water of Changshou Lake Reservoir, Chongqing

To understand the water pollution status and environmental risks of Changshou Lake, the concentrations of heavy metals (Cr, Cu, Zn, As, Cd, and Pb) in the water were collected and analyzed during different seasons. The study investigated temporal and spatial variations, distribution characteristics, pollution levels, and health risks associated with heavy metals in Changshou Lake. The results showed that all six heavy metals were below than the Class Ⅰ standard of the Surface Water Environmental Quality Standard (GB 3838-2002), but recent years have witnessed an increasing trend, with Cu, As, and Pb showing a significant increase (P<0.05). The temporal and spatial distributions of these heavy metals were different. Temporally, Cr and Cd concentrations in surface water were higher in summer, As and Zn were higher in spring, and Pb and Cu were higher in autumn and winter. Spatially, the concentrations of Cr, As, Cu, Zn, and Pb showed higher concentrations in the southern outlet of the reservoir, the northwestern Longxi River inlet, and the central part of the reservoir, whereas Cd was higher in the northern stagnant area. The overall levels of heavy metals in the water body of Changshou Lake were low, with Cr and Cu slightly polluted, while other heavy metals were identified as having an insignificant pollution level. Drinking water was the primary exposure pathway to carcinogenic and non-carcinogenic heavy metals in surface water bodies. The health risk values of Cr and As in water bodies were high, ranging from 6.2×10-10 to 3.0×10-4 and 5.1×10-8 to 3.9×10-5, respectively. The corresponding contribution rates for children and adults to the total health risk were high, with Cr accounting for 87.18% and 87.20%, respectively, while As accounted for 12.73% and 12.71%, respectively. Therefore, it is crucial to prioritize environmental risks associated with Cr and Cu, as well as the health risks associated with Cr and As in Changshou Lake These findings provide a scientific foundation for water pollution control and environmental quality improvement in Changshou Lake, and rational development and utilization of water resources.

Rice-based integrated farming system improves the soil quality, bacterial community structure and system productivity under sub-humid tropical condition.

Rice-based integrated farming system improves the productivity and profitability by recycling resources efficiently. In the sub-humid tropics, rice production without sufficient nutrient replenishment often leads to soil health and fertility degradation. There has been very limited research on soil health and fertility after adopting a multi-enterprising rice-based integrated farming system (IFS), notably in the rice-fish-livestock and agroforestry system, when compared to a conventional farming system (CS). Therefore, the present study analyzed the dynamics of soil properties, soil bacterial community structure and their possible interaction mechanisms, as well as their effect on regulating soil quality and production in IFS, IFSw (water stagnant area of IFS) and CS. The results indicated that soil nutrient dynamics, bacterial diversity indices (Shannon index, Simpson index, Chao 1, ACE and Fisher index) and system productivity were higher in IFSw and IFS compared to CS. Moreover, relative operational taxonomic units of dominant bacterial genera (Chloroflexi, Acidobacteria, Verrucomicrobia, Planctomycetes, Cyanobacteria, Crenarchaeota and Gemmatimonadetes) were also higher in IFSw and IFS compared to CS. Mean soil quality index (SQI) was highest in IFSw (0.780 ± 0.201) followed by IFS (0.770 ± 0.080) and CS (0.595 ± 0.244). Moreover, rice equivalent yields (REY) and rice yields were well correlated with the higher levels of soil biological indices (SQIBiol) in IFS. Overall, our results revealed that rice-based IFS improved the soil health and fertility and ensuing crop productivity through positive interaction with soil bacterial communities and nutrient stoichiometry leading to agroecosystem sustainability.

Investigation of liquid retention behavior in the flow field plate of large-size proton exchange membrane fuel cells: Effects of sub-distribution zone

For proton exchange membrane fuel cells (PEMFCs) featuring an active area exceeding 100 cm2, it is essential to incorporate a sub-distribution zone on both the inlet and outlet sides of the flow field plate to ensure optimal reactant distribution. However, the outlet sub-distribution zones improve liquid water removal resistance and cause cell performance degradation. This study quantitively described the water removal with time and velocity in a straight channel and evaluated the effects of sub-distribution zone for structural optimization. A three-dimensional (3D), two-phase model using the volume of fluid (VOF) method was used to investigate the dynamic liquid retention behaviors in channel with and without sub-distribution zone. The result shows that the liquid retention ratio varies exponentially with time and gas velocity under the liquid-gas shear stress. Meanwhile, it was found that the gas stagnant area created by barriers in the sub-distribution zone significantly enhances liquid retention. Therefore, this study compared the removal capacity in different sub-distribution zones and concluded that liquid removal can be accelerated by improving the breaking up and appropriately reducing the gas stagnant area. The proposed droplet-shaped barrier could serve as an effective water management method for large-size PEMFCs.

Barrier effect, blocking effect, and interference effect of electrohydrodynamic heat transfer enhancement in rectangular channels

This study investigates the heat transfer enhancement by electrohydrodynamic (EHD) in a rectangular channel with various geometric and operational parameters in a wide NEHD range of 0.4–5. Here, NEHD is a dimensionless number, describing the ratio of electrostatic, inertial, and viscous forces. Two working regimes in EHD are identified: inertial and electrostatic regimes. The results show that the barrier effect exists only in the inertial regime; however, the interference effect occurs in the electrostatic regime. The barrier effect relies heavily on NEHD rather than the dimensionless distance between electrodes l* and the dimensionless channel width H* because the thermal boundary layer cannot be disturbed sufficiently by a small electrostatic force; however, the interference effect depends on l* and H* rather than NEHD due to the stagnant area initiated only by a strong interaction between adjacent emitting electrodes. A new effect, the “blocking effect,” is found in the electrostatic regime. The mechanism of the blocking effect is different from that of the barrier and interference effects. The blocking effect is initiated by a giant vortex, which “blocks” the airflow flowing toward the downstream channel. The average Nusselt number of channels can be reduced by at least 8%, 13%, and 5% for the barrier, interference, and blocking effects, respectively. A working spectrum of EHD-induced heat transfer enhancement in a rectangular channel is provided under NEHD and channel area coupling conditions. We believe the spectrum can help in designing EHD-induced heat transfer enhancement because it provides theoretical guidance for avoiding the three effects.

Hydrodynamic and dissolved oxygen–biochemical oxygen demand transport characteristics at the river confluence in China's largest alluvial plain—A modeling study

AbstractThe Yellow River flows through multiple provinces in China, shaping the North China Plain, the largest alluvial plain in China. As the control node of basin ecological environment, the confluence of Weihe River and Yellow River is deemed as the gateway to North China Plain. In this study, a numerical simulation of the Weihe River–Yellow River confluence is conducted using a 2D hydrodynamic model and a coupled transport model for dissolved oxygen–biochemical oxygen demand. The results show that: (i) The typical flow field with multiple backflow areas is formed at the stagnant area where main stream and tributary converge and abrupt channel change area in different hydrological periods. The spur dike here mainly affects the velocity of the Weihe River outlet. (ii) There is an obvious concentration transition mixing zone downstream of the confluence, and the width of the mixing zone gradually linear increases with the direction of water flow. (iii) The self‐purification ability of the confluence is strongest in dry period, weaker in level period, and weakest in wet period. Water bodies have stronger self‐purification capacity on riverbanks than in the middle, and it is stronger in the upper reaches of Weihe River compared to Yellow River. Lower reaches also have a stronger self‐purification capacity than upper reaches. The study results can serve as a scientific reference for protecting the ecological environment of the Yellow River.

The Hydrodynamic Impact of the South-to-North Water Diversion Project on the Lower-reach Lake of Nansi Lake

In order to study the changes in hydrodynamic characteristics of the lower-reach lake of Nansi Lake, this paper established a two-dimensional hydrodynamic model of the lower-reach lake of Nansi Lake based on topography, like rainfall, evaporation, and wind field of the lower-reach lake of Nansi Lake, and carried out water level verification, which is representative and can reflect the process of water level and flow velocity changes of the lower-reach lake of Nansi Lake before and after the South-to-North Water Transfer. The model results show that, before the Nansi Lake was connected to water, the lake area of Zhaoyang Lake in the north was long and narrow and the water level was high. The overall flow velocity of Weishan Lake was low, and the stagnant water area and low flow velocity area accounted for a large proportion. After the opening of the southern four lakes, the high-water level area is concentrated in the wide Weishan Lake area, the water level in the Zhaoyang Lake area is reduced, and the changes between different water level gradients tend to be gentler, and the mobility of the water body is greatly improved.

Effects of lignite composition on reservoir structure, water–gas-bearing features and gas enrichment

The significant variation in production in different blocks has seriously restricted the large-scale breakthrough of China’s low-rank coalbed methane industry for a long time. This study describes in detail the effects of lignite composition on reservoir structure, gas-bearing characteristics, and methane enrichment in the Erlian Basin, thus providing a theoretical basis for accurate exploration of lignite methane. Homogenization of huminite-rich lignite results in the disappearance of cellular structure, closure of cell cavity, small pore size, and low proportion of macropore. The cell wall of inertinite-rich lignite is thin, the cell structure is well preserved, and many cellular pores are developed, providing abundant macropore space. The inertinite-rich lignite contains larger pores and throats, and the content of high coordination number pores is also more abundant. Reservoir characteristics further control the occurrence, migration, and preservation of methane. The inertinite bands provide good seepage space and channels for lignite. The inertinite-rich lignite has high permeability and a low proportion of adsorbed methane, so methane has high mobility in it. The huminite-rich lignite has an excellent “self-sealing” effect on the gas. Overall, huminite-rich lignite in the stagnant area and inertinite-rich lignite in the regional structural culmination are potential favorable positions for the enrichment of lignite methane. Moreover, the interbedded thick coal seam of huminite-rich lignite and inertinite-rich lignite can provide advantageous conditions for water infiltration and gas preservation, thus forming a complete combination of “source, reservoir, and cap rock” in the thick lignite itself.

Measured Rainfall Infiltration and the Infiltration Interface Effect on Double-Layer Loess Slope

It is of great theoretical and engineering significance to carry out field rainfall tests and research on double-layer soil slopes in loess areas. Based on the developed rainfall simulation system with slow-moving injection, field rainfall tests were carried out on a natural double-layer loess slope. The characteristics of volumetric water content were monitored, and the rainfall infiltration characteristics and infiltration effect at the interface of the soil layer were analyzed by numerical simulation. The results showed the fastest infiltration at the top platform of the slope, followed by that at the upper surface of the slope, and the slowest infiltration at the lower surface of the slope during rainfall. Under various rainfall intensities, the erosion of the upper silty loess slope was greater than that of the lower clay loess slope, and the erosion patterns were quite different at the end of rainfall. During the infiltration process in the double-layer loess slope, a stagnant transition area was formed near the interface of the soil layer. The equipotential line of water content in the stagnant transition area of the upper region was roughly parallel to the slope surface, and the equipotential line in the lower region was roughly parallel to the interface of the soil layer. With an increase in rainfall intensity, the upper transition area at the interface of the soil layer continued to extend from the slope surface inward, showing the interface infiltration effect that became increasingly significant with the intensification of rainfall. The infiltration effect at the soil layer interface could provide an evaluation basis for rainfall infiltration analyses of multi-layer soil slopes.

Optical measurement approach to analyse the tool-workpiece interacting flow of grinding processes

Investigations of the coolant flow within a running grinding machine are carried out to examine the flow behaviour of the coolant in interaction with the grinding wheel and the workpiece. The aim of the investigations is to understand the interaction between fluid, workpiece and tool, to eventually correlate flow dynamics with cooling efficiency. Flow measurements are obtained with Particle Image Velocimetry (PIV), utilising the visualisation of flow structures of the metal working fluid (MWF). Measurements without workpiece provide a fundamental understanding of the MWF-tool interaction, i.e. the flow deflection and entrainment of the MWF with the tool. A limitation of the MWF entrainment into the contact zone occurs for higher inflow velocities, indicating a maximum cooling capacity for inflow velocities around 80% of the circumferential velocity of the tool.To enable the investigation of the MWF-tool-workpiece interaction, an optical transparent workpiece is designed and implemented into the grinding machine. Flow measurements in the decreasing gap between the workpiece and the rotating grinding wheel reveal a deceleration stagnation of the flow before the beginning of the contact zone. As a result, the PIV-based measurements of the time-averaged MWF flow field in the running grinding machine provide the necessary data basis to understand the flow-based cooling mechanisms in grinding processes. For varying inflow velocities, a nearly constant position of the stagnant flow area is measured, confirming the shown results of a maximum useful flow rate.

Investigating mixing patterns of suspended sediment in a river confluence using high-resolution hyperspectral imagery

In a river confluence, the fluvial process is complex because of the merging of different flows from rivers with distinct morphologies. However, the mixing of suspended sediment in river confluences has been inadequately investigated owing to the low resolution of conventional techniques for measuring suspended sediment. In this study, we investigated the mixing of suspended sediment at the confluence of the Hwang and Nakdong Rivers in South Korea by analyzing the spectral characteristics of suspended sediment from high-resolution hyperspectral data. We retrieved the suspended sediment concentration (SSC) from high-resolution hyperspectral imagery using the conversion technique, which is a cluster-based machine learning regression with optical variability. Hyperspectral clustering was first applied to classify the water regions of the main river (Nakdong) and its tributary (Hwang). The clustering result at a near-field after the confluence point was strongly related to the mixing degree of flow and sediments from two different rivers. Through segmentation, regressors with hyperspectral clusters enabled accurate SSC measurement. In particular, they precisely retrieved the concentrations adjacent to the mixing layer, even when the relationship between the spectral data and suspended sediment concentrations of the main river and tributary was substantially different. Using a detailed SSC map, we compared two cases of mixing patterns by calculating the variation in sediment concentration along the downstream river confluence. We found that the mixing pattern was different because of the flow velocity and a large sandbar near the stagnant area even though river discharge was similar for both cases. In the slow mixing case, the sandbar caused a velocity-deficit with a wake that reduced the variance of SSC due to the irregular flow near the mixing layer. In this case, dual counter-rotating secondary flow cells also limited mixing across the post-confluence reach. However, when the wake and dual counter-rotating secondary flows weakened due to the erosion of the sandbar and lower flow velocity, the transverse mixing coefficient increased by approximately 40 % compared to the slow mixing case. This study demonstrated that the hyperspectral approach can be used to investigate the mixing of suspended sediment in greater detail in complex river systems, as it provides high-resolution information that conventional measurement methods cannot explore.

Effects of ellipsoidal and regular hexahedral particles on the performance of the waste heat recovery equipment in a methanol reforming hydrogen production system

Hydrogen production from methanol has attracted attention due to its wide range of raw material sources and mature technology. Using waste heat of industrial high temperature solid particles like blast slag and steel slag etc. To provide vaporization heat and reaction heat for the reaction between methanol and water is an emerging technology for hydrogen production from methanol, which can save additional thermal energy resources. Herein, the performances of equipment that uses the waste heat of ellipsoidal and regular hexahedral particles to provide a heat source for methanol to hydrogen were explored by the DEM-CFD method. Compared with spherical particles of the same equivalent diameter, ellipsoidal and regular hexahedral particles have poor fluidity in the stagnant area, and the empty area is enlarged and irregular in shape. The average velocity peaks of the ellipsoidal and regular hexahedron particles are larger than those of spherical particles, and the overall mean velocity fluctuation of ellipsoidal particles is similar to that of spherical particles while the regular hexahedron particles' is larger. The average temperature drop rate of the ellipsoidal and regular hexahedral particles is slower than that of spherical particles, the uniformity of temperature distribution is worse than that of spherical particles. The ellipsoidal and regular hexahedral particles’ average effective heat transfer coefficient is smaller than that of spherical particles, and the heat transfer effect is weaker than that of spherical particles. The effective heat transfer coefficient of ellipsoidal particles is 2.95 W/(m−2∙K−1) lower than that of spherical particles and the effective heat transfer coefficient of hexahedral particles is 6.09 W/(m−2∙K−1) lower than that of spherical particles. Therefore, compared with the spherical particles of the same equivalent diameter, ellipsoidal and regular hexahedral particles produce less hydrogen.

A Study on the Occurrence Characteristics of Harmful Blue-Green Algae in Stagnant Rivers Using Machine Learning

Several changes have occurred in the river environment of Nakdong river due to the construction of multifunctional weirs as part of the Four Major Rivers Project. This river currently exhibits characteristics that are similar to those of a stagnant water area in which the river depth increases and the flow velocity decreases. Consequently, blue-green algae are frequently observed. Toxic substances secreted by blue-green algae are harmful to aquatic ecosystems and the human body; therefore, ensuring the stability of the water quality of Nakdong river is of utmost importance. Various factors are associated with the occurrence of blue-green algae. Therefore, the causal relationship between these causative factors must be identified. In this study, we investigated factors influencing algal growth, such as water quality, hydraulics, and weather, and algal occurrence patterns by site were analyzed. Recent studies have used data mining and machine-learning techniques in algal management to quantitatively identify the characteristics of blue-green algae. In machine learning, the prediction results differ depending on the selection of parameters, which are an important aspect in the management of blue-green algae with complex causes. In this study, we quantitatively analyzed the conditions for the occurrence of cyanobacteria according to the influencing factors using decision trees and random forests, which are machine-learning techniques, along with an analysis of the major complex factors influencing the occurrence of blue-green algae in the Nakdong river weirs. Considering the water quality and hydraulic factors, we analyzed the characteristics of algal generation in each weir at different hydraulic volume times. In addition, we investigated the possibility of improving the accuracy of cyanobacterial prediction according to the learning factors. Through these analyses, we attempted to study the characteristics of blue-green algae in stagnant rivers.

Differences in accumulation patterns of low-rank coalbed methane in China under the control of the first coalification jump

The considerable variations in coalbed methane (CBM) production in different low-rank basins have attracted widespread attention. Moreover, the occurrence of the “first coalification jump” (FCJ) has increased the uncertainty in the accumulation law. Following systematic sample collections of different ranks and lithotypes, the variation of material composition, methane source, reservoir properties, occurrence state, and enrichment rule under FCJ control was studied. Low-rank CBM is mainly obtained from microbial gases abundantly found in lignite and subbituminous coal. The microbial methane of lignite and sub-bituminous coal accounted for about 86.46% and 77.83%, respectively. As its maturity increases, thermogenic gas can provide a supplement to methane in subbituminous coal. Lignite has a low degree of coalification and retains a large amount of primary plant tissue structure. It is characterized by high porosity and a high proportion of macropores. The low adsorption capacity and high porosity result in a substantially higher proportion of free gas in lignite reservoirs than in subbituminous coal reservoirs. The free gases in lignite reservoirs have stronger mobility and are easily enriched in the structural culmination. Owing to coalification, the subbituminous coal’s porosity is considerably reduced. Thus, micropores and transition pores dominate subbituminous coal. The methane adsorbed in subbituminous coal is primarily concentrated in the stagnant area in the syncline and mixed “thermogenic/microbial” genetic areas. It is difficult to use a unified model to explain the gas distribution. Therefore, taking typical types of basins (foreland, craton, and fault subsidence basins) as examples, we summarize the differences in low-rank CBM enrichment patterns under FCJ control and provide a basis for detailed exploration and efficient development of CBM.

Numerical simulation of inherent boric mixing phenomenon inside reactor annular down-comer

The inherent boric mixing phenomenon inside the reactor down-comer was numerically investigated by this paper. The boric tracer distribution was compared with the experimental data, and the renormalization group model (RNG) was considered as the most suitable turbulence model. When the boric solution entered the down-comer through the inlet, it dispersed radially in the disk shape and spread along the annulus. As the injection arrived at the position of 120°, the transverse velocity decayed and the vertical velocity increased significantly. Subsequently, the injection tended to fall vertically into the lower space. Two flow stagnant zones were discovered, which were unfavorable for the homogeneous mixing. The down-comer was divided into the first mixture zone, the second mixture zone and the ambient water zone. The mass fraction of the first zone was homogeneously distributed, and the mass fraction gradient of the second zone was quite large. The injection accumulated in the upper space of the down-comer when the inlet Reynolds number was 2272. As the Reynolds number was increased to 13632, the injection entered the lower space by the disk-shaped scattering flow. The flow stagnant area was compressed when the thickness of the down-comer was reduced. According to the coefficient of variation analysis, increasing the inlet Reynolds number and decreasing the down-comer thickness were beneficial to the inherent boric mixing.

Destratification of a Eutrophic Reservoir in South Korea Using a Novel Convectional Water Circulation System (CWCS)

Replication of natural mixing through artificial water circulation techniques, such as convectional water circulation systems (CWCS), can break thermal stratification in stagnant water and suppress algal blooms. Here, the field performance of a novel CWCS was evaluated in a eutrophic reservoir (Shingal reservoir, South Korea) for three seasons between September 2016 and September 2018. The CWCS was deployed in a corner of stagnated water in the reservoir. The changes in water temperature and dissolved oxygen (DO) concentrations at different water depths were examined at the deployment site and two control sites within the stagnant area during the 2016 and 2017 seasons. In 2018, the performance of the CWCS in replicating natural mixing was assessed by monitoring water temperature changes at different depths at the CWCS unit deployment site and a comparison site with natural water flow. The differences in water temperature and DO concentrations between the epilimnion and the hypolimnion were significantly smaller at the deployment site than at the control sites, demonstrating the effectiveness of the CWCS in vertical and horizontal mixing as well as in oxygen transfer. The findings of the field study revealed that the CWCS effectively induced natural-like mixing without disturbing the hypolimnion.

Alpine glacier surface velocity measurement from UAV imagery – examining the effect of image resolution on the accuracy of results

The reliability and validity of the Glacier Surface Velocity (GSV) measurement results based on remote sensing datasets depends on the quality and spatial resolution of the image used. The typical pixel size of space-borne satellite imagery is often larger than the annual and inter-annual displacement of small alpine debris-covered glaciers. In addition, the pixel size of medium resolution satellite images (10–30 m), limits the size of a feature that can be matched. This is even more of an issue for glaciers located in arid and semi-arid environments (e.g. glaciers in Iran and high mountains of Asia) where flow velocities are not exceeding a few metres per year. Consequently, high-resolution data such as Unmanned Aerial Vehicle (UAV) images are required to calculate the surface velocity of such glaciers. However, the optimal resolution of UAV images is one of the most important challenges in GSV measurement. This paper explores the influence of UAV image resolution on the quality of GSV results. Analysis was carried out at 19 different resolutions of UAV images from 10 to 100 cm with a 5 cm bin over a debris-covered glacier, in Iran. COSI-Corr algorithm was used to perform the image correlation. To evaluate the accuracy of obtained results, manual digitisation was performed and the differences between manual GSV and frequency cross-correlator were assessed for all data sets. Moreover, displacement calculated for a stagnant off-glacier area was evaluated. While the quality of the results of the images between 10 and 30 cm is substantially the same, the obtained results indicate that the best result of GSV was not obtained using the finest image resolution. Results revealed that the highest correspondence between the measured GSV and manual digitisation was obtained in a 30 cm spatial resolution image. In addition, the 30 cm image resolution shows the minimum uncertainty over the off-glacier static area. Obtained results revealed that using too fine resolution images will lead to computational redundancy, while no improvement is observed in the accuracy of GSV results.

Stagnation Zone Near A Corner In Viscoplastic Fluid Flow

Abstract The shape, size and location of the stagnation zone between flat non-parallel walls that make up the corner of a tube with non-circular cross section through which a phase change material of the Bingham plastic type flows is investigated. We show that the stagnant area is bounded by a convex meniscus whose size depends on the degree of plasticity and the vertex angle. The maximum and minimum energy dissipation occurs at the wall and at the bisectrix, respectively. The stagnant zone can be altogether avoided by modifying the shape of the wall in the corner area. A new design of the cross section of the tube that allows reducing or eliminating this area to optimize the mass transport is developed. Two optimal solutions, a vertex with a straight cut and a concavely curved vertex, are proposed.

Flow velocities of the debris-covered Miyar Glacier, western Himalaya, India

ABSTRACT Spatiotemporal surface velocity measurements of the alpine valley type debris-covered Miyar Glacier of the Chandrabhaga (Chenab) basin, western Himalaya, were assessed based on the cross-correlation of Landsat images spanning nearly three decades (1992-2019). Long-term (1950-2015) temperature and precipitation trends were evaluated using Asian Precipitation Highly Resolved Observational Data Integration Towards Evaluation (APHRODITE) datasets. The mean velocity (1992-2019) of the Miyar Glacier is ∼29 m/yr, with spatial patterns revealing that the debris-covered tongue is nearly stagnant (∼5 m/yr) compared to the debris-free up-glacier zone (∼35 m/yr). The transition zone from clean to debris-covered ice in the mid-ablation area shows the highest long-term mean velocities of ∼60 m/yr during the observation period, likely resulting from a steep surface gradient and greater ice thickness than the other regions of this glacier. The slow-moving and nearly stagnant debris-covered area reveals the highest amount of surface lowering due to the expansion of supraglacial ponds. Miyar Glacier experiences summer speed-up of ∼67–80% in seasonal velocity compared to winter, interpreted as a result from enhanced basal sliding during summer months due to warmer temperatures inputting more meltwater into the subsurface drainage system. Inter-annual velocity variations are greatest in the upper glacier, with higher velocities observed more frequently in recent decades. Future work should aim to elucidate the causes of this pattern, considering the overall rising air temperature trend in the western Himalaya.

ТЕОРЕТИЧЕСКОЕ ОПИСАНИЕ ПРОЦЕССА ПОДОГРЕВА ГАЗОВОЗДУШНОЙ СМЕСИ В КОРПУСЕ ГОРЕЛКИ С ТЕПЛОВЫМ РАССЕКАТЕЛЕМ

The main thermal processes occurring during the operation of a gas burner device for household use are considered. One of the important functions performed by the gas burner device is the preparation of fuel for subsequent combustion. The efficiency and quality of the combustion process directly depends on the temperature of the gas-air mixture. Since an increase in the temperature of the mixture contributes to the intensification of the combustion process, when designing gas burner devices, it is useful to determine the temperature of the gas-air mixture inside the burner body. We have proposed a solution that makes it possible to increase the efficiency of the gas burner device by intensifying the preheating from the thermal divider to the gas-air mixture inside the body of the gas burner. It has been established that the placement of the thermal divider in the central part on the inner side of the cover allows one to reduce the stagnant zone area when the flow of the gas-air mixture moves, and the conical shape of the thermal divider provides minimal resistance to the movement of the gas-air mixture flow inside the gas burner, in addition, the side surface of the thermal divider additionally increases the area heat transfer. An expression is obtained for calculating the average temperature of the gas-air mixture at the outlet from the firing holes of the gas burner.

Distribution Characteristics of C-N-S Microorganism Genes in Different Hydraulic Zones of High-Rank Coal Reservoirs in Southern Qinshui Basin.

Microbial decomposition of carbon and biogenic methane in coal is one of the most important issues in CBM exploration. Using metagenomic technologies, the microbial C–N–S functional genes in different hydraulic zones of high-rank coal reservoirs were systematically studied, demonstrating the high sensitivity of this ecosystem to hydrodynamic conditions. The results show that the hydrodynamic strength of coal reservoir #3 in the Shizhuangnan block gradually weakened from east to west, forming a transitional feature from a runoff area to a stagnant area. Compared with runoff areas, stagnant areas have higher reservoir pressure, gas content, and ion concentrations. The relative abundance of genes associated with C, N, and S cycling increased from the runoff area to the stagnant area, including cellulose-degrading genes (e.g., cellulose 1,4-beta-cellobiosidase), methane metabolism genes (e.g., mcr, fwd, mtd, mer, and mtr), N-cycling genes (e.g., nifDKH, amoB, narGHI, napAB, nirK, norC, and nosZ), and S-cycling genes (e.g., dsrAB, sir, cysN, sat, aprAB, and PAPSS). This indicates that the stagnant zone had a more active microbial C–N–S cycle. The machine learning model shows that these significantly different genes could be used as effective indices to distinguish runoff and stagnant areas. Carbon and hydrogen isotopes indicate that methane in the study area was thermally generated. Methanogens compete with anaerobic heterotrophic bacteria to metabolize limited substrates, resulting in a low abundance of methanogens. In addition, the existence of methane-oxidizing bacteria suggests that biogenic methane was consumed by methanotrophic bacteria, which is the main reason why biogenic methane in the study area was not effectively preserved. In addition, weakened hydrodynamic conditions increased genes involved in nutrient cycling, including organic matter decomposition, methanogenesis, denitrification, and sulfate reduction, which contributed to the increase in CO2 and consumption of sulfate and nitrate from runoff areas to stagnant areas.