Pumping-induced Well Hydraulics and Groundwater Budget in a Leaky Aquifer System with Vertical Heterogeneity in Aquitard Hydraulic Properties

In groundwater hydrology,aquitard heterogeneity is often less considered compared to aquifers,despite its significant impact on groundwater hydraulics and groundwater resources evaluation.A semi-analytical solution is derived for pumping-induced well hydraulics and groundwater budget with consideration of vertical heterogeneity in aquitard hydraulic conductivity(K)and specific storage(S_(s)).The proposed new solution is innovative in its partitioning of the aquitard into multiple homogeneous sub-layers to enable consideration of various forms of vertically heterogeneous K or S_(s).Two scenarios of analytical investigations are explored:one is the presence of aquitard interlayers with distinct K or S_(s) values,a common field-scale occurrence;another is an exponentially depth-decaying aquitard S_(s),a regional-scale phenomenon supported by statistical analysis.Analytical investigations reveal that a low-K interlayer can significantly increase aquifer drawdown and enhance aquifer/aquitard depletion;a high-S_(s) interlayer can noticeably reduce aquifer drawdown and increase aquitard depletion.Locations of low-K or high-S_(s) interlayers also significantly impact well hydraulics and groundwater budget.In the context of an exponentially depth-decaying aquitard S_(s),a larger decay exponent can enhance aquifer drawdown.When using current models with a vertically homogeneous aquitard,half the sum of the geometric and harmonic means of exponentially depth-decaying aquitard S_(s) should be used to calculate aquitard depletion and unconfined aquifer leakage.

Study on the interannual variability of the Kerama Gap transport and its relation to the Kuroshio/Ryukyu Current system

An analysis of a 68-year monthly hindcast output from an eddy-resolving ocean general circulation model reveals the relationship between the interannual variability of the Kerama Gap transport(KGT)and the Kuroshio/Ryukyu Current system.The study found a significant difference in the interannual variability of the upstream and downstream transports of the East China Sea-(ECS-)Kuroshio and the Ryukyu Current.The interannual variability of the KGT was found to be of paramount importance in causing the differences between the upstream and downstream ECS-Kuroshio.Additionally,it contributed approximately 37%to the variability of the Ryukyu Current.The interannual variability of the KGT was well described by a two-layer rotating hydraulic theory.It was dominated by its subsurface-intensified flow core,and the upper layer transport made a weaker negative contribution to the total KGT.The subsurface flow core was found to be mainly driven by the subsurface pressure head across the Kerama Gap,and the pressure head was further dominated by the subsurface density anomalies on the Pacific side.These density anomalies could be traced back to the eastern open ocean,and their propagation speed was estimated to be about 7.4 km/d,which is consistent with the speed of the local first-order baroclinic Rossby wave.When the negative(positive)density anomaly signal reached the southern region of the Kerama Gap,it triggered the increase(decrease)of the KGT towards the Pacific side and the formation of an anticyclonic(cyclonic)vortex by baroclinic adjustment.Meanwhile,there is an increase(decrease)in the upstream transport of the entire Kuroshio/Ryukyu Current system and an offshore flow that decreases(increases)the downstream Ryukyu Current.

Design and Sizing of an Ecological Wastewater Treatment System in a School Environment: A Case Study of Ndiebene Gandiol 1 School

The primary objective of this study was to design and size a sustainable sanitation solution for the Ndiebene Gandiol 1 school located in the eponymous commune in northern Senegal. Field investigations led to the collection of wastewater samples. Their analysis revealed specific pollutant loads, including loads of BOD5 3.6966 kgO2/day and COD of 12.8775 kgO2/day, which were central to the design phase. Following a rigorous assessment of the existing sanitation infrastructure, constructed wetland (CWs) emerged as the most appropriate ecological solution. This system, valued for its ability to effectively remove contaminants, was tailored to the specific needs of the site. Consequently, the final design of the filter extends over 217.16 m2, divided into two cells of 108.58 m2 each, with dimensions of 12.77 m in length and 8.5 m in width. The depth of the filtering medium is approximately 0.60 m, meeting the standards while ensuring maximized purification. Typha, an indigenous and prolific plant known for its purification abilities, was selected as the filtering agent. Concurrently, non-crushed gravel was chosen for its proven filtration capacity. This study is the result of a combination of scientific rigor and design expertise. It provides a holistic view of sanitation for Ndiebene Gandiol. The technical specifications and dimensions of the constructed wetland filter embody an approach that marries indepth analysis and practical application, all aimed at delivering an effective and long-lasting solution to the local sanitation challenges. By integrating precise scientific data with sanitation design expertise, this study delivers a holistic solution for Ndiebene Gandiol. The detailed dimensions and specifications of the constructed wetland filter reflect a methodology that combines meticulous analysis with practical adaptation, aiming to provide an effective and sustainable response to the challenges of rural and school sanitation in the northern region of Senegal.

Design and Test of Closed Hydraulic Transmission System of 4WD High-clearance Wheeled Sprayer

In conjunction with the working characteristics of the high-clearance wheeled sprayer and the benefits of the closed hydraulic system,a series of reasonable working parameters should be established,and a hydraulic system that fulfills the requisite specifications should be designed.The AMESim software model is employed to construct a closed hydraulic transmission system,and the simulation analysis is then performed according to the data of hydraulic components.According to analysis results,the prototype can be optimized and upgraded,and a verification test is further carried out.The test results demonstrate that the designed closed hydraulic transmission system meets the actual working requirements of the high-clearance wheeled sprayer and provides a stable experimental platform for intelligent control of agricultural machinery.

Ecological Wastewater Treatment System in a School Environment Using a Horizontal Flow Biological Reactor: The Case of Typha

The overarching goal of this study is to offer an effective and sustainable solution to the challenges of sanitation in rural and school settings in the northern region of Senegal. The study explores a wastewater treatment approach based on phytoremediation, with a particular focus on the use of horizontally-flowing reed bed filters. Furthermore, it aims to adapt and optimize these systems for the specific needs of Senegal, focusing on wastewater in school environments. Thus, we constructed a horizontally-flowing reed bed filter, planted with Typha, at the Ndiébène Gandiol school in Senegal. We will investigate the efficiency of wastewater treatment by this horizontally-flowing reed bed filter, emphasizing the role of the plant used: Typha. The filter is described in detail, specifying its dimensions, its composition of flint gravel, and the choice of plants, namely Typha. The experimental protocol is detailed, describing the sampling at the entrance and exit of the filter to evaluate water quality. The parameters analyzed include Chemical Oxygen Demand (COD), Biochemical Oxygen Demand over 5 days (BOD5), suspended solids, ammonium, nitrates, phosphates, pH, conductivity, and fecal coliforms. The results indicate a significant improvement in water quality after treatment. COD, BOD5, suspended solids, and fecal coliforms are greatly reduced, thus demonstrating the efficacy of the Typha filter. However, nitrate concentrations remain relatively stable, suggesting room for improvement in their elimination. A perspective of reuse of the treated water is considered, showing that the effluents from the planted filter meet Senegalese and international standards for irrigation. The findings suggest that these waters could be used for a variety of crops, thereby reducing the pressure on freshwater resources. In conclusion, the Typha-based filtration system shows promising results for improving water quality in this region of Senegal. However, adjustments are necessary for more effective nitrate removal. This study paves the way for sustainable use of treated wastewater for irrigation, thus contributing to food security and the preservation of water resources.

Ecological Wastewater Treatment System Using a Horizontal Flow Biological Reactor: The Case of Vetiver

Confronted with the challenge of wastewater management, particularly in the school environment of Senegal, our study set out to achieve multiple objectives. Following field surveys, laboratory analyses of wastewater samples were carried out, revealing a significant pollutant load. In the community of Gandiol, near Saint-Louis (Senegal), the school of Ndiebene Gandiol 1 faces significant sanitation challenges. Our study aimed to address this issue by using a constructed filter composed of two filtering bed cells measuring 12 × 8.5 m, preceded by a septic tank. We particularly focused on the influence of Vetiver;a plant chosen for its purification potential. Our analyses showed remarkable efficiency of the filter. Elimination rates reached 95% for 5-Day Biochemical Oxygen Demand (BOD5), 91% for Chemical Oxygen Demand (COD), and 92% for SS, far exceeding the Senegalese standards set at 50 mg/L, 200 mg/L, and 40 mg/L, respectively. Furthermore, the concentration of fecal coliforms was reduced to 176 FCU/100mL, well below the Senegalese threshold of 2000 FCU/100mL and close to the World Health Organization’s (WHO) recommendation of 1000 FCU/100mL. However, despite these promising results, some parameters, particularly the concentration of certain pollutants, approached the thresholds defined by European legislation. For example, for Suspended Solids (SS), the post-treatment level of 3 mg/L was well below the Senegalese standard but edged close to the European minimum of 10 mg/L. In conclusion, the Vetiver filter demonstrated a remarkable ability to treat school wastewater, offering high pollutant elimination percentages. These results suggest significant opportunities for the reuse of treated water, potentially in areas such as irrigation, though some adjustments may be necessary to meet the strictest standards such as those of the European union (EU).

Leaf hydraulics coordinated with leaf economics and leaf size in mangrove species along a salinity gradient

Independence among leaf economics,leaf hydraulics and leaf size confers plants great capability in adapting to heterogeneous environments.However,it remains unclear whether the independence of the leaf traits revealed across species still holds within species,especially under stressed conditions.Here,a suite of traits in these dimensions were measured in leaves and roots of a typical mangrove species,Ceriops tagal,which grows in habitats with a similar sunny and hot environment but different soil salinity in southern China.Compared with C.tagal under low soil salinity,C.tagal under high soil salinity had lower photosynthetic capacity,as indicated directly by a lower leaf nitrogen concentration and higher water use efficiency,and indirectly by a higher investment in defense function and thinner palisade tissue;had lower water transport capacity,as evidenced by thinner leaf minor veins and thinner root vessels;and also had much smaller single leaf area.Leaf economics,hydraulics and leaf size of the mangrove species appear to be coordinated as one trait dimension,which likely stemmed from covariation of soil water and nutrient availability along the salinity gradient.The intraspecific leaf trait relationship under a stressful environment is insightful for our understanding of plant adaption to the multifarious environments.

Adjacent mode resonance of a hydraulic pipe system consisting of parallel pipes coupled at middle points

The coupling vibration of a hydraulic pipe system consisting of two pipes is studied.The pipes are installed in parallel and fixed at their ends,and are restrained by clips to one bracket at their middle points.The pipe subjected to the basement excitation at the left end is named as the active pipe,while the pipe without excitation is called the passive pipe.The clips between the two pipes are the bridge for the vibration energy.The adjacent natural frequencies will enhance the vibration coupling.The governing equation of the coupled system is deduced by the generalized Hamilton principle,and is discretized to the modal space.The modal correction is used during the discretization.The investigation on the natural characters indicates that the adjacent natural frequencies can be adjusted by the stiffness of the two clips and bracket.The harmonic balance method(HBM)is used to study the responses in the adjacent natural frequency region.The results show that the vibration energy transmits from the active pipe to the passive pipe swimmingly via the clips together with a flexible bracket,while the locations of them are not node points.The adjacent natural frequencies may arouse wide resonance curves with two peaks for both pipes.The stiffness of the clip and bracket can release the vibration coupling.It is suggested that the stiffness of the clip on the passive pipe should be weak and the bracket should be strong enough.In this way,the vibration energy is reflected by the almost rigid bracket,and is hard to transfer to the passive pipe via a soft clip.The best choice is to set the clips at the pipe node points.The current work gives some suggestions for weakening the coupled vibration during the dynamic design of a coupled hydraulic pipe system.

Backstepping Sliding Mode Control Based on Extended State Observer for Hydraulic Servo System

Hydraulic servo system plays an important role in industrial fields due to the advantages of high response,small size-to-power ratio and large driving force.However,inherent nonlinear behaviors and modeling uncertainties are the main obstacles for hydraulic servo system to achieve high tracking perfor-mance.To deal with these difficulties,this paper presents a backstepping sliding mode controller to improve the dynamic tracking performance and anti-interfer-ence ability.For this purpose,the nonlinear dynamic model is firstly established,where the nonlinear behaviors and modeling uncertainties are lumped as one term.Then,the extended state observer is introduced to estimate the lumped distur-bance.The system stability is proved by using the Lyapunov stability theorem.Finally,comparative simulation and experimental are conducted on a hydraulic servo system platform to verify the efficiency of the proposed control scheme.

Dynamic Simulation and Test Verifcation of Hydraulic Automatic Tensioner for an Engine Timing Chain Drive System

As a fundamental component of an automobile engine’s timing chain drive system, the hydraulic automatic tensioner signifcantly enhances fuel economy while minimizing system vibrations and noise. However, there is a noticeable lack of research on automatic hydraulic tensioners. This study presents a comprehensive calculation approach for the principal parameters of a hydraulic automatic tensioner. An efective method, grounded in hydraulics and multibody dynamics, was introduced for estimating the dynamic response of such a tensioner. The simulation model developed for the hydraulic tensioner is characterized by its rapid dynamic response, consistent operation, and high accuracy. The dynamic behavior of the tensioner was analyzed under varying boundary conditions, using sinusoidal signal excitation. It was observed that the maximum damping force increases with a decreasing leakage gap. Conversely, an increase in oil temperature or air content leads to a decrease in the maximum damping force. The reaction forces derived from these calculations align well with experimental results. This calculation and simulation approach ofers considerable value for the design of innovative hydraulic tensioners. It not only streamlines the design phase, minimizes the number of trials, and reduces product costs, but also provides robust insights for evaluating the performance of hydraulic tensioners.

The role of temperature‐enhanced fault closure in promoting postinjection pressure diffusion and seismicity in enhanced geothermal systems

Post shut‐in seismic events in enhanced geothermal systems(EGSs)occur predominantly at the outer rim of the co‐injection seismic cloud.The concept of postinjection fracture and fault closure near the injection well has been proposed and validated as a mechanism for enhancing post shut‐in pressure diffusion that promotes seismic hazard.This phenomenon is primarily attributed to the poro‐elastic closure of fractures resulting from the reduction of wellbore pressure after injection termination.However,the thermal effects in EGSs,mainly including heat transfer and thermal stress,may not be trivial and their role in postinjection fault closure and pressure evolution needs to be explored.In this study,we performed numerical simulations to analyze the relative importance of poro‐elasticity,heat transfer,and thermo‐elasticity in promoting postinjection fault closure and pressure diffusion.The numerical model wasfirst validated against analytical solutions in terms offluid pressure diffusion and against heatedflow‐through experiments in terms of thermal processes.We then quantified and distinguished the contribution of each individual mechanism by comparing four different shut‐in scenarios simulated under different coupled conditions.Our results highlight the importance of poro‐elastic fault closure in promoting postinjection pressure buildup and seismicity,and suggest that heat transfer can further augment the fault closure‐induced pressure increase and thus potentially intensify the postinjection seismic hazard,with minimal contribution from thermo‐elasticity.

基于ADAMS/Hydraulics的连续阀口流量数学模型的建立

阀口流量计算模型是ADAMS/Hydraulics中建立各种液压元件最基本的数学模型。为得到连续的阀口压力流量曲线 ,对层流流量系数Cdl采用多项式拟合的方法 ,建立了ADAMS/Hydraulics中使用的阀口流量计算模型 ,为用户正确定义液压元件的各种参数提供理论依据。

ADAMS／Hydraulics模块的研究与应用

简要介绍了ADAMS及其Hydraulics模块,给出了使用ADAMS/Hydraulics模块遇到的问题和注意事项,并进行了实例应用,得出利用ADAMS/Hydraulics可以在同一界面下对机械系统和液压系统进行实时的协同仿真。

基于ADAMS/Hydraulics模块的液压离合器液压系统仿真

简要介绍ADAMS及其Hydraulics模块的特点,利用ADAMS/Hydraulics模块建立液压离合器模型,同时对液压离合器的液压系统进行仿真研究。结果表明,液压离合器在液压缸的驱动下,可以完成工作过程中的主要动作,工作安全可靠,液压缸运行平稳,无较大冲击,为液压离合器液压系统的进一步研究及优化提供参考。

Aging Mongolian pine plantations face high risks of drought-induced growth decline:evidence from both individual tree and forest stand measurements

Discerning vulnerability differences among different aged trees to drought-driven growth decline or to mortality is critical to implement age-specific countermeasures for forest management in water-limited areas.An important species for afforestation in dry environments of northern China,Mongolian pine(Pinus sylvestris var.mongolica Litv.)has recently exhibited growth decline and dieback on many sites,particularly pronounced in old-growth plantations.However,changes in response to drought stress by this species with age as well as the underlying mechanisms are poorly understood.In this study,tree-ring data and remotely sensed vegetation data were combined to investigate variations in growth at individual tree and stand scales for young(9-13 years)and aging(35-52 years)plantations of Mongolian pine in a water-limited area of northern China.A recent decline in tree-ring width in the older plantation also had lower values in satellited-derived normalized difference vegetation indices and normalized difference water indices relative to the younger plantations.In addition,all measured growth-related metrics were strongly correlated with the self-calibrating Palmer drought severity index during the growing season in the older plantation.Sensitivity of growth to drought of the older plantation might be attributed to more severe hydraulic limitations,as reflected by their lower sapwood-and leaf-specific hydraulic conductivities.Our study presents a comprehensive view on changes of growth with age by integrating multiple methods and provides an explanation from the perspective of plant hydraulics for growth decline with age.The results indicate that old-growth Mongolian pine plantations in water-limited environments may face increased growth declines under the context of climate warming and drying.

Hydraulic properties and drought response of a tropical bamboo (Cephalostachyum pergracile)

Bamboo plants are an essential component of tropical ecosystems,yet their vulnerability to climate extremes,such as drought,is poorly understood due to limited knowledge of their hydraulic properties.Cephalostachyum pergracile,a commonly used tropical bamboo species,exhibited a substantially higher mortality rate than other co-occurring bamboos during a severe drought event in 2019,but the underlying mechanisms remain unclear.This study investigated the leaf and stem hydraulic traits related to drought responses,including leaf-stem embolism resistance(P50leaf;P50stem) estimated using optical and X-ray microtomography methods,leaf pressure-volume and water-releasing curves.Additionally,we investigated the seasonal water potentials,native embolism level(PLC) and xylem water source using stable isotope.We found that C.pergracile exhibited strong resistance to embolism,showing low P50leaf,P50stem,and turgor loss point,despite its rapid leaf water loss.Interestingly,its leaves displayed greater resistance to embolism than its stem,suggesting a lack of effective hydraulic vulnerability segmentation(HVS) to protect the stem from excessive xylem tension.During the dry season,approximately 49% of the water was absorbed from the upper 20-cm-deep soil layer.Consequently,significant diurnal variation in leaf water potentials and an increase in midday PLC from 5.87±2.33% in the wet season to 12.87±4.09%in the dry season were observed.In summary,this study demonstrated that the rapid leaf water loss,high reliance on surface water,and a lack of effective HVS in C.pergracile accelerated water depletion and increased xylem embolism even in the typical dry season,which may explain its high mortality rate during extreme drought events in 2019.

Stress tensor determination by modified hydraulic tests on pre-existing fractures:Method and stress constraints

The hydraulic testing of pre-existing fractures(HTPF)is one of the most promising in situ stress measurement methods,particularly for three-dimensional stress tensor determination.However,the stress tensor determination based on the HTPF method requires at least six tests or a minimum of 14-15 tests(under different conditions)for reliable results.In this study,we modified the HTPF method by considering the shear stress on each pre-existing fracture,which increased the number of equations for the stress tensor determination and decreased the number of tests required.Different shear stresses were attributed to different fractures by random sampling;therefore,the stress tensors were obtained by searching for the optimal solution using the least squares criterion based on the Monte Carlo method.Thereafter,we constrained the stress tensor based on the tensile strength criterion,compressive strength criterion,and vertical stress constraints.The inverted stress tensors were presented and analyzed based on the tensorial nature of the stress using the Euclidean mean stress tensor.Two stress-measurement campaigns in Weifang(Shandong Province,China)and Mercantour road tunnel(France)were implemented to highlight the validity and efficiency of the modified HTPF(M-HTPF)method.The results showed that the M-HTPF method can be applied for stress tensor inversion using only three to four tests on pre-existing fractures,neglecting the stress gradient.The inversion results were confined to relatively small distribution dispersions and were significantly reliable and stable due to the shear stresses on the fractures and the stress constraints employed.The M-HTPF method is highly feasible and efficient for complete stress tensor determination in a single borehole.

Unraveling the hydraulic properties of loess for landslide prediction:A study on variations in loess landslides in Lanzhou,Dingxi,and Tianshui,China

Loess has distinctive characteristics,leading to frequent landslide disasters and posing serious threats to the lives and properties of local re sidents.The involvement of water repre sents a critical factor in inducing loess landslides.This study focuses on three neighboring cities sequentially situated on the Loess Plateau along the direction of aeolian deposition of loess,namely Lanzhou,Dingxi,and Tianshui,which are densely populated and prone to landslide disasters.The variations in hydraulic properties,including water retention capacity and permeability,are investigated through Soil Water Characteristic Curve(SWCC)test and hydraulic conductivity test.The experimental findings revealed that Tianshui loess exhibited the highest water retention capacity,followed by Dingxi loess,while Lanzhou loess demonstrated the lowest water retention capacity.Contrastingly,the results for the saturated permeability coefficient were found to be the opposite:Tianshui loess showed the lowest permeability,whereas Lanzhou loess displayed the highest permeability.These results are supported and analyzed by scanning electron microscopy(SEM)observation.In addition,the water retention capacity is mathematically expressed using the van Genuchten model and extended to predict unsaturated hydraulic properties of loess.The experimental results exhibit a strong accordance with one another and align with the regional distribution patterns of disasters.

Spatiotemporal variations of sand hydraulic conductivity by microbial application methods

The spatiotemporal distributions of microbes in soil by different methods could affect the efficacy of the microbes to reduce the soil hydraulic conductivity.In this study,the specimens of bio-mediated sands were prepared using three different methods,i.e.injecting,mixing,and pouring a given microbial so-lution onto compacted sand specimens.The hydraulic conductivity was measured by constant-head tests,while any soil microstructural changes due to addition of the microbes were observed by scan-ning electron microscope(SEM)and mercury intrusion porosimetry(MIP)tests.The amount of dextran concentration produced by microbes in each type of specimen was quantified by a refractometer.Results show that dextran production increased exponentially after 5-7 d of microbial settling with the supply of culture medium.The injection and mixing methods resulted in a similar amount and uniform dis-tribution of dextran in the specimens.The pouring method,however,produced a nonuniform distri-bution,with a higher concentration near the specimen surface.As the supply of culture medium discontinued,the dextran content near the surface produced by the pouring method decreased dramatically due to high competition for nutrients with foreign colonies.Average dextran concentration was negatively and correlated with hydraulic conductivity of bio-mediated soils exponentially,due to the clogging of large soil pores by dextran.The hydraulic conductivity of the injection and mixing cases did not change significantly when the supply of culture medium was absent.

Experimental Investigation on Vertical Hydraulic Transport of Ores in Deepsea Mining

Deepsea mining has been proposed since the 1960s to alleviate the lack of resources on land.Vertical hydraulic transport of collected ores from the seabed to the sea surface is considered the most promising method for industrial applications.In the present study,an indoor model test of the vertical hydraulic transport of particles was conducted.A noncontact optical method has been proposed to measure the local characteristics of the particles inside a vertical pipe,including the local concentration and particle velocity.The hydraulic gradient of ore transport was evaluated with various particle size distributions,particle densities,feeding concentrations and mixture flow velocities.During transport,the local concentration is larger than the feeding concentration,whereas the particle velocity is less than the mixture velocity.The qualitative effects of the local concentration and local fluid velocity on the particle velocity and slip velocity were investigated.The local fluid velocity contributes significantly to particle velocity and slip velocity,whereas the effect of the local concentration is marginal.A higher feeding concentration and mixture flow velocity result in an increased hydraulic gradient.The effect of the particle size gradation is slight,whereas the particle density plays a crucial role in the transport.