Using Visual MODFLOW Model to Assess the Efficiency of Subsurface Barrier Wall for Groundwater Flow Regulation and Reduction of Saline Intrution

Barrier walls effectively store water,regulate underground flows,improve exploitable reserves and prevent saltwater intrusion.The effectiveness of the underground barrier wall depends not only on the hydrogeological structure,the technical parameters of the wall but also on the layout scheme of the exploitation well system.The results showed that in natural conditions,the ground water level upstream of the barrier wall rose in the presence of a barrier wall.In wells located downstream of high barrier walls,the water level decreased.The amount of underground current flowing into the sea decreased,the annual average value of the whole region decreased was 316 m3/day and night.In presence of a wall,both the water level and the amount of evaporation increased.The average increase in evaporation volume during the calculation period of ten thousand days with walls was 4.114 m3/d.So in presence of a wall,the amount of water that can be exploited increases by the total amount of evaporation plus the decrease in discharge to the sea and is equal to 4,424 m3/d.In the exploitation condition,if the water level in the presence of wall is kept as low as in the absence of wall,the exploitation flow will increase to about 4,400 m3/day and night.From the calculated water level values when there is a wall and without a wall,we can see that if the exploitation flow in presence of a wall and in the absence of wall is the same,the water level drop at the calculated observation wells upstream of the wall will decrease from 0.21 m to 3.97 m.The condition of effective exploitation of the wall depends on the mining scheme.The exploitation scheme is reasonable,the exploitation flow of the wells does not exceed the allowable flow so as not to cause the drying of the aquifer at the location of the well.The upstream area of the wall reflects quite clearly as the Total dissolved solids content in observation wells upstream of the wall at the end of the calculation time is significantly reduced compared to that without the wall,ranging from 69 mg/L to 5,629 mg/L.In the presence of a wall,the water level of observation wells upstream of the wall is higher than that of without a wall from 0.10 m to 0.74 m.

Hierarchical Task Planning for Power Line Flow Regulation

The complexity and uncertainty in power systems cause great challenges to controlling power grids.As a popular data-driven technique,deep reinforcement learning(DRL)attracts attention in the control of power grids.However,DRL has some inherent drawbacks in terms of data efficiency and explainability.This paper presents a novel hierarchical task planning(HTP)approach,bridging planning and DRL,to the task of power line flow regulation.First,we introduce a threelevel task hierarchy to model the task and model the sequence of task units on each level as a task planning-Markov decision processes(TP-MDPs).Second,we model the task as a sequential decision-making problem and introduce a higher planner and a lower planner in HTP to handle different levels of task units.In addition,we introduce a two-layer knowledge graph that can update dynamically during the planning procedure to assist HTP.Experimental results conducted on the IEEE 118-bus and IEEE 300-bus systems demonstrate our HTP approach outperforms proximal policy optimization,a state-of-the-art deep reinforcement learning(DRL)approach,improving efficiency by 26.16%and 6.86%on both systems.

Design and Verification for Dual⁃mode CDFS and High⁃Load Compressor with a Large Flow Regulation Range

This paper presents the design and verification of the dual-mode core driven fan stage(CDFS)and high-load compressor with a large flow regulation range.In view of the characteristics of large flow regulation range of the two modes and high average stage load coefficient,this paper investigates the design technology of the dual-mode high-efficiency compressor with a large flow regulation range and high-load compressor with an average stage load coefficient of 0.504.Building upon this research,the design of the dual-mode CDFS and four-stage compressor is completed,and three-dimensional numerical simulation of the two modes is carried out.Finally,performance experiment is conducted to verify the result of three-dimensional numerical simulation.The experiment results show that the compressor performance is improved for the whole working conditions by using the new design method,which realizes the complete fusion design of the CDFS and high-pressure compressor(HPC).The matching mechanism of stage characteristics of single and double bypass modes and the variation rule of different adjustment angles on performance are studied comprehensively.Furthermore,it effectively reduces the length and weight of compressor,and breaks through the key technologies such as high-load compressor with the average load factor of 0.504.These findings provide valuable data and a methodological foundation for the development of the next generation aeroengine.

Flow Regulation and Heat Transfer Characteristics in a Novel Turbine Shroud with Internal Asymmetric Throttle Chamber

Flow and heat transfer of a novel turbine shroud with throttle chamber under two kinds of orifice arrangements were numerically studied. The original shroud model composed of the impingement holes, film holes and jet channel. The two modified models have identical geometrical spacing except for the number and location of the orifices in the upper plate of the throttle chamber added in the jet channel. Different pressure values were set at the outlets of different row film holes simulating the mainstream favorable pressure gradient. The ratios of inlet total pressures of impingement holes to outlet static pressures of the third row film holes ranged from 1.6 to 3.6. The Nusselt number distributions were validated by the experimental data. The main target of this study was to quantify the impact of the throttle chamber on the flow regulation and internal heat transfer characteristics. The flow factor, relative mass flow rate, the Nusselt number and the heat transfer factors on the target walls were presented. It is found that the mass flow rate distributions in the film hole rows become more reasonable by the modification of location and number of the orifices on the throttle chamber. The throttle chamber decreases the heat transfer on the target walls.

Influence of cardiac nerve status on cardiovascular regulation and cardioprotection

Neural elements of the intrinsic cardiac nervous system transduce sensory inputs from the heart, blood vessels and other organs to ensure adequate cardiac function on a beat-to-beat basis. This inter-organ crosstalk is critical for normal function of the heart and other organs; derangements within the nervous system hierarchy contribute to pathogenesis of organ dysfunction. The role of intact cardiac nerves in development of, as well as protection against, ischemic injury is of current interest since it may involve recruitment of intrinsic cardiac ganglia. For instance, ischemic conditioning, a novel protection strategy against organ injury, and in particular remote conditioning, is likely mediated by activation of neural pathways or by endogenous cytoprotective bloodborne substances that stimulate different signalling pathways. This discovery reinforces the concept that inter-organ communication, and maintenance thereof, is key. As such, greater understanding of mechanisms and elucidation of treatment strategies is imperative to improve clinical outcomes particularly in patients with comorbidities. For instance, autonomic imbalance between sympathetic and parasympathetic nervous system regulation can initiate cardiovascular autonomic neuropathy that compromises cardiac stability and function. Neuromodulation therapies that directly target the intrinsic cardiac nervous system or other elements of the nervous system hierarchy are currently being investigated for treatment of different maladies in animal and human studies.

Mid-Term Preliminary Results for Safety and Patency of the Occlutech Atrial Flow Regulator in an Animal Model

Objective:The Atrial Flow Regulator(AFR)is a double disc device made of self-expanding Nitinol wire mesh,structured around a central lumen.Once deployed via the transfemoral route,the device stents the atrial septum leaving a preselected fixed diameter atrial communication.We sought to evaluate the mid-term performance of the AFR by implanting the device in 5 healthy porcine hearts to assess safety and patency of the device fenestration over a period of 150 days.Method:Five AFR devices were implanted in 5 female Yucatan adult minipigs.The animals were survived to 150 days with periodic assessments at days+3,+30,+60,+90,+120,and+150.These assessments consisted of transesophageal echocardiography and fluoroscopic evaluation.The animals were sacrificed at day+150.Histological and pathological assessments were carried out to characterize neointimal tissue growth,inflammation,thrombus formation,endothelial coverage,endothelial maturity,and the presence of any luminal thrombus.Result:There were no unscheduled deaths.Patency was maintained in all 5 animals across the 150-day study.There was no statistically significant difference in the lumen diameter over the study duration.Neointimal growth was mild to moderate in all specimens and occurred mostly on the surfaces of the device in direct contact with the atrial septum.There was no evidence of any significant inflammatory response on routine blood work or by imaging or histological assessment.Scanning electron microscope(SEM)examination showed nearly complete surface coverage with endothelial tissue.The animals were in a healthy condition for the duration of the study with no attributable pathology and no adverse effects noted on distant organs in any of the 5 animals.Conclusion:As a continuation of our earlier work,this 150-day midterm animal study provides important safety and feasibility information.Our preliminary results show that the AFR is both safe and effective in maintaining a sustainable atrial level communication for the duration of the study.

AB042.Pericytes on microvessels lead to vascular dysfunction during retinal ischemia

Background:Pericytes are contractile cells that wrap along the walls of capillaries.In the brain,pericytes play a crucial role in the regulation of capillary diameter and vascular blood flow in response to metabolic demand.During ischemia,it has been suggested that pericytes may constrict capillaries,and that pericytes remain constricted after reperfusion thus resulting in impaired blood flow.Methods:Here,we used a mouse model of retinal ischemia based on ligation of the central retinal artery to characterize the role of pericytes on capillary constriction.Ischemia was induced in transgenic mice carrying the NG2 promoter driving red fluorescent protein expression to selectively visualize pericytes(line NG2:DsRed).Changes in retinal capillary diameter at 1 hr after ischemia were measured ex vivo in whole-mounted retinas from ischemic and control eyes(n=4-6/group)using a stereological approach.Vessels and pericytes were three-dimensionally reconstructed using IMARIS(Bitplane).Furthermore,we used a novel and minimally invasive two-photon microscopy approach that allowed live imaging of microvasculature changes in the retina.Results:Our data show a generalized reduction in capillary diameter in ischemic retinas relative to sham-operated controls in all vascular plexus(ischemia:4.7±0.2μm,control:5.2±0.2µm,student’s t-test,P<0.001).Analysis of the number of capillary constrictions at pericyte locations,visualized in NG2:DsRed mice,demonstrated a substantial increase in ischemic retinas relative to the physiological capillary diameter reductions observed in controls(ischemia:1,038±277 constrictions at pericyte locations,control:60±36 constrictions at pericyte locations,student’s t-test,P<0.01).Live imaging using two-photon microscopy confirmed robust capillary constriction at the level of pericytes on retinal capillaries during ischemia(n=6-8/group).Conclusions:Collectively,our data demonstrate that ischemia promotes rapid pericyte constriction on retinal capillaries causing major microvascular dysfunction in this tissue.To identify the molecular mechanisms underlying the pathological response of pericytes during ischemia,we are currently carrying out experiments in mice and zebrafish to modulate signaling pathways involved in calcium dynamics leading to contractility in these cells.

On the Blood Pressure in the Cardiovascular System

Background: Hemodynamics is a practical and complicated theoretical problem. The aim of this paper is to analyze the characteristics of blood pressure in the cardiovascular system changing with the mechanical parameters of blood vessels and the storage of some visceral organs. Method: The fluid network model was used for the study. The cardiovascular system was modeled as a system consisting of 20 segments of vessels. The main controlling parameters were determined first by using dimensional analysis. Then the responses of blood pressure of each segment of vessels were analyzed by changing the controlling parameters. Results: The parameters of the blood vessel of brain have the least influence on the pressures of other parts. The pressures of the system of blood vessels will decrease if some blood is stored in the liver or the abdominal vein system. Vice versa. The effects of regulation of blood on the variation of blood pressure are larger than the other controlling parameters. Conclusions: The controlling parameters of the abdominal aorta and ascending aorta affect greatly the blood pressure of each vessel.

THE FLOW CONTROL IN PIPELINE SYSTEM

An automatic control technique for the flow regulation in pipeline systems is developed in the paper. The improvement for the previous work is the use of an optimal observer that reduces greatly the time of changing now states and the adaptability for the regulation of frictioness now. By first order Taylor-expanding the frictioness flow equations of motion and continuity at equilibrium states, a set of linear equations are obtained then, the linear quadratic design technique in automatic control theory is used to control the now states. In order to avoid measuring all states, an optimal state estimator is constructed. A pipeline system is taken as example. The regulation results are satisfactory. If the changes of discharges are within 20%, the method developed in this paper is effective for valve-motion synthesis in real pipeline systems.

Non-isolated stacked bidirectional soft-switching DC-DC converter with PWM plus phase-shift control scheme

In this paper, a non-isolated stacked bidirectional DC-DC converter with zero-voltage-switching(ZVS) is introduced for the high step-up/step-down conversion systems. The extremely narrow turn-on and/or turn-off duty cycle existing in the conventional bidirectional buck-boost converters can be extended due to the stacked module configuration for large voltage conversion ratio applications. Furthermore, the switch voltage stress is halved because of the series connection of half bridge modules. The PWM plus phase-shift control strategy is employed, where the duty cycle is adopted to regulate the voltages between the input and output sides and the phaseshift angle is applied to achieve the power flow regulation.This decoupled control scheme can not only realize seamless bidirectional transition operation, but also achieve adaptive voltage balance for the power switches. In addition, ZVS soft-switching operation for all active switches is realized to minimize the switching losses. Finally, a prototype of 1 kW operating at 100 kHz is built and tested to demonstrate the effectiveness of the proposed converter and the control strategy.