Pumping Stage Research Articles

Electric energy consumption (EEC) in groundwater-based drinking water supply systems: analysis and comparison of seven Italian case studies

ABSTRACT Drinking water and wastewater services depend on energy: electric energy consumption (EEC) of this sector amounts to 2–3% of global EEC. The attention of the scientific community and of water utilities about this topic is focused on energy optimization of wastewater treatment plants and pumping stages in drinking water supply systems (DWSSs). However, because of increasingly stringent regulations and because of more and more extended water-source pollution, the need for ‘unconventional’ drinking water treatment systems, which are very energy-intensive, will bring treatment to be a key factor in this scenario. Analyzing EEC in seven full-scale DWSSs, we wanted to control EEC in every single stage of the DWSS (withdrawal, drinking water treatment plant (DWTP) and distribution) and to identify opportunities for reducing energy consumption in DWSS, with a special focus on each drinking water treatment process. The most energy-intensive unconventional treatment turns out to be membrane filtration by reverse osmosis (for which specific consumption per cubic meter of pumped water is equal to 0.243 Wh/m3), whereas the most energy-intensive conventional treatment turns out to be air oxidation (specific EEC from 0.012 to 0.087 kWh/m3). The main strategies for energy conservation can be applied both in management and in the design phase.

Modeling Study of Enhanced Coal Seam Gas Extraction via N2 Injection Under Thermal-Hydraulic-Mechanical Interactions.

N2 injection into coal seams can effectively enhance the gas flow capacity in the late stage of pumping, thereby improving the recovery rate and recovery efficiency of low coalbed methane (CBM). To reveal the thermodynamic flow coupling relationship between the reservoir and the gas phase and its transportation mechanism in the process of thermal N2 injection, a mathematical coupling model of N2 injection that considers the deformation of the coal seam, fluid transportation, and temperature change was established. The influence of the seepage heat transfer effect of the coal seam under the effect of N2 injection on the CH4 extraction rate was investigated using this model. Results indicate that the action mechanism of N2 injection in coal seams includes increasing seepage, promoting flow, and displacing gases. A higher initial coal seam temperature results in a smaller thermal expansion and deformation of the coal skeleton during thermal N2 injection and less pronounced coal permeability increase. A larger initial coal seam permeability results in more favorable N2 diffusion, which strengthens the flow-promoting effect on CH4. The effect of gas injection pressure on CH4 recovery is greater than that of the gas injection temperature: High pressure promotes N2 seepage, carries CH4 flow, and increases the CH4 diffusion effect, whereas higher temperature promotes the desorption of adsorbed gas in the coal seam and improves the recovery rate.

Comparing different segments in shut-in pressure signals: new insights into frequency range and energy distribution

Water hammer diagnostics is an important fracturing diagnosis technique to evaluate fracture locations and other downhole events in fracturing. The evaluation results are obtained by analyzing shut-in water hammer pressure signal. The field-sampled water hammer signal is often disturbed by noise interference. Noise interference exists in various pumping stages during water hammer diagnostics, with significantly different frequency range and energy distribution. Clarifying the differences in frequency range and energy distribution between effective water hammer signals and noise is the basis of setting specific filtering parameters, including filtering frequency range and energy thresholds. Filtering specifically could separate the effective signal and noise, which is the key to ensuring the accuracy of water hammer diagnosis. As an emerging technique, there is a lack of research on the frequency range and energy distribution of effective signals in water hammer diagnostics. In this paper, the frequency range and energy distribution characteristics of field-sampled water hammer signals were clarified quantitatively and qualitatively for the first time by a newly proposed comprehensive water hammer segmentation-energy analysis method. The water hammer signals were preprocessed and divided into three segments, including pre-shut-in, water hammer oscillation, and leak-off segment. Then, the three segments were analyzed by energy analysis and correlation analysis. The results indicated that, one aspect, the frequency range of water hammer oscillation spans from 0 to 0.65 Hz, considered as effective water hammer signal. The pre-shut-in and leak-off segment ranges from 0 to 0.35 Hz and 0 to 0.2 Hz respectively. Meanwhile, odd harmonics were manifested in water hammer oscillation segment, with the harmonic frequencies ranging approximately from 0.07 to 0.75 Hz. Whereas integer harmonics were observed in pre-shut-in segment, ranging from 6 to 40 Hz. The other aspect, the energy distribution of water hammer signals was analyzed in different frequency ranges. In 0 − 1 Hz, an exponential decay was observed in all three segments. In 1 − 100 Hz, a periodical energy distribution was observed in pre-shut-in segment, an exponential decay was observed in water hammer oscillation, and an even energy distribution was observed in leak-off segment. In 100 − 500 Hz, an even energy distribution was observed in those three segments, yet the highest magnitude was noted in leak-off segment. In this study, the effective frequency range and energy distribution characteristics of the field-sampled water hammer signals in different segments were sufficiently elucidated quantitatively and qualitatively for the first time, laying the groundwork for optimizing the filtering parameters of the field filtering models and advancing the accuracy of identifying downhole event locations.

Enhanced harris hawks optimization based load frequency control of multi area microgrid based water treatment plant with consideration of 3DOF-(FO-PIDN)/(TIDN) controller

Municipal water supply system (WSS) consist of different pumping stages viz. intake, water treatment plant (WTP) and intermediate pumping station (IPS). Usually, the power supply for WSS is obtained through public power tapping sources. However, this often leads to load shedding and disruption of the water supply. This paper focuses on the concept, considering WSS as a multi-source multi-area microgrid scheme, this includes renewable energy sources (RES) such as solar, wind, etc. Moreover, the study incorporates a Battery Energy Storage System (BESS) and a Diesel Engine Generator (DEG) to provide power supply during peak demand at each pumping station. Frequency control is essential for optimizing system performance. This paper proposes Enhanced Harris Hawks Optimization Algorithm (EHHO) based PID controller for regulating the frequency in the multi-microgrid-based water supply system. The proposed controller is implemented in MATLAB simulation software, and its response is compared with other optimization methods such as Particle Swarm Optimization (PSO) and Grey Wolf Optimization (GWO). Moreover, implementation and comparison of higher degree order controller such as 3DOF-FOPIDN controller and 3DOF-TIDN controllers are tested under PSO method to observe the performance as well as robustness of the controller. The results indicate that the proposed controller provides better performance in controlling the load frequency deviation, thus improving the efficiency and reliability of the multi-microgrid system for consideration of municipal water supply.

Организация подачи (транспортировки) огнетушащих веществ на тушение пожаров способом перекачки

Purpose. For the first time ever the article comprehensively considers issues related to water supply (transportation) to the seat of extinguishing large scale fires over long distances. The authors pay special attention to the conditions determining the choice of pumping as a way of supplying water over long distances. Recommendations are given on the choice of water pumping method and its practical implementation at the fire scene. The calculation method of pump and hose systems implemented during pumping and the express method for determining pumping parameters for practical workers are presented. Methods. Based on extinguishing large scale fires data analysis, topical issues on extinguishing agents supply (transportation) by pumping method were identified, analytical calculations of pump-hose systems parameters implemented when pumping water to the seat of extinguishing large scale fires were made, taking into account tactical and technical characteristics of modern fire trucks. Findings. The proposed method (algorithm) allows converting analytical calculations into accurate calculation system (express method) using a spreadsheet or nomograph. For the first time ever the express calculation table shows the dependence of pumping parameters on the distance between the water source and fire source and the water flow rates supplied by fire pressure hoses. This table allows determining the need of water pumping supply to the fire scene and determining the number of pumping stages; number of fire pressure hoses for pumping; pressure on water tenders fire pumps operating in pumping. Express method provides calculation of water pumping parameters from pump to pump via one or two main hose lines. Research application field. Based on this study, the team of authors developed “Recommendations for applying fire departments tactical capabilities at extinguishing fires and conducting emergency rescue operations.” Conclusions. . Knowledge and application of conditions determining the choice of pumping as a method of supplying (transportation) water over long distances, recommendations for choosing a pumping water method, as well as the methodology for calculating hose systems parameters, the number of main fire trucks for supplying fire extinguishing agents to the fire scene by pumping will increase the level of tactical training of the fire chief. The proposed express method for determining the pumping parameters according to the nomograph allows the fire chief and other officials to reduce the time for making managerial decisions and organizing the supply (transportation) of water for fire extinguishment, as well as reduce the area of extinguishing fires and reduce economic and material damage from them.

CFD-DEM simulation of proppant pack stability during flowback in a rough fracture using supercritical CO2

The destabilization of proppant packs during flowback, leading to undesirable consequences such as choke points (fracture closure near the wellbore) and proppant production, is a critical concern in fracturing operations. Despite its significance, comprehensive investigations into proppant pack stability during flowback remain limited, particularly in supercritical CO2 (Sc-CO2) fracturing. This study addresses this gap by employing an experimentally validated coupled Computational Fluid Dynamics–Discrete Element Method (CFD–DEM) model, integrated with a heat transfer model, to analyze proppant pack stability in Sc-CO2 fracturing near the wellbore. An authentic proppant pack for flowback analysis is generated by simulating proppant pack development during the pumping stage and subsequent compression during the fracture closure stage in a synthetic rough fracture. The findings reveal that the flowback stage can be subdivided into three stages: translation-controlled, rolling-controlled, and stable. Proppant pack stability is intricately governed by factors such as fluid drag force, inter-particle contact force, and pre-flowback pack shape. Due to the reduced fluid drag force, the retained proppant ratios rise under varied conditions: from 47.6% to 95.7% with a decrease in flowback rate from 0.3 m/s to 0.1 m/s, from 50.0% to 67.8% with an increase in fluid temperature from 40 °C to 160 °C, and from 16.5% to 80.8% with an increase in proppant size from 0.4 mm to 0.8 mm. In comparison, due to the increased inter-particle contact force, the retained proppant ratio increases by 16.4% as the closure width increases from 0.15 mm to 0.3 mm. Additionally, a longer proppant pack with a front characterized by a higher inclination angle and curved zone exhibits higher stability during flowback. These insights significantly enhance the understanding of proppant pack stability during flowback, offering crucial guidance for designing Sc-CO2 fracturing processes.

Stochastic inversion for equivalent hydraulic fracture characterization using low-frequency distributed acoustic sensing data

Distributed fiber-optic sensing, a game-changing technology, has been successfully applied in monitoring hydraulic fracturing treatments. The cross-well fiber-optic strain/strain-rate responses are directly related to the fracture-propagation process and dynamic fracture geometry. Extracting the insightful information regarding hydraulic fractures requires robust interpretation workflows. In this paper, we aim to develop a stochastic inversion approach to characterize the dynamic equivalent fracture geometry and quantify the associated uncertainties using cross-well low-frequency distributed acoustic sensing (LF-DAS) measurements. A fast analytical forward solver based on the 3D displacement discontinuity method is developed to model the strain. The objective function is the sum-of-squares error between the modeled strain and the measured strain. We focus on an equivalent fracture geometry with a predefined length centered around the monitoring well, which is a reasonable assumption considering the spatial sensitivity of LF-DAS. Therefore, the model parameters reduce to fracture width and height of the equivalent fracture. We adopted the delayed rejection adaptive metropolis (DRAM) algorithm, an efficient Markov-chain Monte Carlo (MCMC)-based method, to perform the optimization. The efficiency and accuracy of the algorithm are tested using a synthetic case that has three monitoring wells at different locations. The mean values of fracture width and height are both close to the true values with negligible standard deviations for all the three monitoring wells. The algorithm performance is not sensitive to the initial guess and the predefined length needs to be large enough. Then, a field case with a single cluster from the HFTS-2 project is presented. The fracture width increases from about 0.5 mm to about 0.9 mm during the pumping stage and gradually decreases during the shut-in period. The fracture height changes during the pumping stage and stabilizes at about 150 m during the shut-in period, the trend of which is consistent with the LF-DAS signals from the offset vertical monitoring well. To the best of our knowledge, this is the first algorithm that can efficiently quantify the fracture width and height simultaneously. The results could provide novel insights on the characteristics of fracture geometry and significantly improve the understanding of complex fracture propagation processes in subsurface reservoirs.

Magnetohydrodynamic Analyses of a Miniature, Dual-Stage Electromagnetic Pump for Lead and Sodium In-Pile Test Loops

To support the development of Generation IV nuclear reactors, in-pile and out-of-pile test loops with miniature, submersible Direct-Current Electromagnetic Pumps (DC-EMPs) are used to investigate compatibility and corrosion issues of nuclear fuel and structure materials with flowing molten lead and alkali liquid metals. Owing to the absence of detailed experimental measurements and because of its simplicity and low computational cost, the Equivalent Circuit Model (ECM) is widely used to predict the pump characteristics. The simplifying assumptions in the ECM contribute to overpredicting the pump characteristics by >10%. To gain insight into the pump operation and assess the effect of various assumptions in ECM, not possible even experimentally, this work performed three-dimensional (3-D), Magneto-Hydro-Dynamic (MHD) analyses of a 66.8-mm-diameter, submersible, dual-stage DC-EMP, recently developed by the authors, for circulating molten Pb and liquid Na at up to 500°C. The solution of the coupled electromagnetism equations and the momentum and energy balance equations calculates the pump characteristics and provides 3-D images of the flow, electric current, and magnetic field strength distributions in the flow duct. The Grid Convergence Index (GCI) criterion confirmed the adequacy of the employed numerical mesh refinement and the results conversion. Results demonstrate strong dependence of the magnetic field strength distribution in the flow duct on the value and the distribution of the electric current but negligible effects of the fluid temperature on joule heating and pump characteristics. The Lorentz force highest densities occur at the entrance of the two pumping stages, and approximately 10.0% of the total force occurs in the fringe regions upstream and downstream of pumping stages. The MHD pump characteristics are in general agreement with, but consistently lower than, the ECM predictions. For molten lead and liquid sodium, the difference between the calculated characteristics increases with increased flow rate and input current, up to 12% and 14%, respectively.

О структуре гидравлических потерь при работе многоступенчатых лопастных насосов

The paper proposes methodology for assessing hydraulic resistance of the vane pump stages. The methodology makes it possible to reveal the hydraulic losses structure during liquid pumping and assess contribution of each type of these losses to the overall balance of the pumping stage energy consumption. Dependence of hydraulic losses on the width of the inter-vane flow channels is shown. Theoretical method was developed to predict the effect achieved by altering the vane design and production technology. Prospects of research, design, development and industrial production of the new type of multistage vane pumps with the oval-type stages are substantiated.

Studying the Transmission Behavior of Two-Phase Flow Oil-Water Mixing Using a Laboratory Multiple Porous Media Model

The formation and flow of emulsions in porous media are common to all technologies used to extract or process oil. In most cases, oil and water emulsions are formed in a porous medium due to oil spills near watery areas or soils containing water. This emulsion leads to a reaction between oil and water, which finds its way to the porous medium. The detailed flow mechanisms of emulsions through porous media are not well understood. In this study, the soil’s oil percentage variation was studied when sand was introduced or an emulsion, i.e., mixed with water, and two porous media, different in composition and physical properties, were used to find out their effect on oil transmission. The percentage of oil and water was calculated at several points at different distances and times. It was noted that the results differed in both mediums due to the difference in permeability, porosity, arrangement of soil particles, compaction process, and other physical properties. Liquids’ viscosity, density, and chemical composition clearly and significantly affect the results. The time for the oil to reach the last point in the pipe differed for both soils. If the time period in the experiment of pumping oil only in sandy soil took 6 hours and the washing process took 3 hours. In organic soil, the time period for the pollutant pumping stage took about 7 hours and the washing stage about 4 hours because the oil is transmitted in sandy soil is faster, but in the experiment of pumping oil and water together, the time period in the process of pumping oil and water together in sandy soil took 4 hours and the washing process 3 hours In organic soil, the period of pumping oil and water together took 5 hours, and the washing period 3 hours, because the percentage of oil was less than in the experiment of pumping oil only. In the soil, that is, if the period of pumping the pollutant increased for more than 15 hours, the oil may reach a distance of more than 4 meters in the soil. As for the washing process, when the oil is mixed with water, it gives better results when washing it than if the oil enters alone into the soil because the proportions of oil when it enters the soil together with the water, it is little and does not rise much, so it is easy to wash.

Mobilization of Heavy Metals in a Saline Confined Aquifer as a Consequence of Rainwater Injection: A Case Study in Southern Vietnam.

An artificial recharge test was performed in Ho Chi Minh City, Vietnam to see the geochemical response of a saline coastal plain aquifer to the injected rainwater. The results show that the rainwater injection can cause mobilization of heavy metals due to pyrite oxidation and this phenomenon can persist even after the full recovery of the injected water. In this study, a 30-m-deep well was installed in a confined aquifer. Pyrite framboids were observed in the sediment samples collected during the well drilling. A total of 400L rainwater was injected into the well for 70min. After waiting 63h, the well was extracted at a pump speed of 2.7L/min and the chemistry of the pumped groundwater was monitored for 10h. The groundwater showed geochemical features close to rainwater at the early stage of pumping and gradually changed to those of the background waters, especially, in electrical conductivity and Cl- concentration, as the pumping proceeded. However, the groundwater pumped in the later stage showed much increased concentrations in SO42-, total iron (FeT), AsT, Ni, Mn and Zn relative to the calculated mixing concentrations due to pyrite oxidation even though NO3-, the pyrite oxidant, already had disappeared. It was revealed from the geochemical modeling that the persistent pyrite oxidation was the result of the reaction with ferrihydrite, which precipitated in pores of the sediment by the injection of aerated water. We believe our study is a good example showing the importance of careful design of the artificial recharge systems to avoid or minimize the geochemical disturbance of aquifer.

A compact gas attenuator for the SwissFEL ATHOS beamline realized using additive manufacturing.

Gas attenuators are important devices providing accurate variation of photon intensity for soft X-ray beamlines. In the SwissFEL ATHOS beamline front-end the space is very limited and an innovative approach has been taken to provide attenuation of three orders of magnitude up to an energy of 1200 eV. Additive manufacturing of a differential pumping system vacuum manifold allowed a triple pumping stage to be realized in a space of less than half a meter. Measurements have shown that the response of the device is as expected from theoretical calculations.

Reactive transport modeling for the effect of pumping activities on the groundwater environment in muddy coasts

Intensive pumping activities threaten the coast groundwater environment and have a negative impact on aquifer systems. A comprehensive understanding of these effects is important for the management of coastal groundwater resources. However, this is challenging, particularly for coastal saline groundwater systems due to complex water–rock interactions. In this study, a coupled variable–density flow and hydrochemical reaction model was used to examine the effects of pumping activities on the groundwater environment on the southern coast of Laizhou Bay, China, which is a typical muddy coast. The model successfully captured the hydrodynamic and hydrochemical changes, and the water–rock interactions, during three different exploitation stages: (1) evaporation and water–rock interactions were the primary controls on groundwater evolution during the weakly pumped stage (before 1995); (2) the groundwater level began to decrease and saltwater intrusion was aggravated during the small pumping stage (1995–2005); and (3) significant hydrodynamic and hydrochemical changes occurred at the saline/freshwater transition and pumping zones during a period of intensive pumping (after 2005). Our findings revealed that water–rock interactions are the primary drivers of hydrochemical evolution at the saline/freshwater transition and seaward saline groundwater zone, whereas hydrodynamic changes are the main drivers in the pumping and deep saline–brine water zones. Furthermore, we discussed the effects of hydrodynamic variations and water–rock interactions on the aquifer matrix and identified that irreversible changes occurred mainly in the pumping zone and saline/freshwater transition. In conclusion, our study highlights the importance of considering both hydrodynamic and hydrogeochemical factors when managing coastal groundwater resources. By developing a better understanding of these complex interactions, we can minimize the negative impacts of pumping activities and preserve the long-term sustainability of coastal groundwater resources.

SmartLact8: A Bio-Inspired Robotic Breast Pump for Customized and Comfort Milk Expression.

According to the 2018 National Immunization Survey conducted by the Center for Disease Control and Prevention (CDC), 83.9% of the breastfeeding mothers in the United States have used a breast pump at least once. However, the majority of existing products use a vacuum-only mechanism to extract milk. This causes common breast injuries such as nipple soreness, breast-tissue damage, and lactation complications after pumping. The objective of this work was to develop a bio-inspired breast pump prototype, named as SmartLac8, that can mimic infant suckling patterns. The input vacuum pressure pattern and compression forces are inspired from term infants' natural oral suckling dynamics captured in prior clinical experiments. Open-loop input-output data are used to perform system identification for two different pumping stages that facilitates controller design for closed-loop stability and control. A physical breast pump prototype with soft pneumatic actuators and custom piezoelectric sensors was successfully developed, calibrated, and tested in dry lab experiments. Compression and vacuum pressure dynamics were successfully coordinated to mimic the infant's feeding mechanism. Experimental data on sucking frequency and pressure on the breast phantom were consistent with clinical findings.

Analysis of the interaction between surface water and groundwater using gaseous tracers in a dynamic test at a riverbank filtration intake

AbstractWe discuss a study designed to elucidate the genesis and inflow conditions at riverbank filtration wells located on a mountain river. This article seeks to identify the most important drivers of spatio‐temporal dynamics of water flow in the hyporheic exchange zone, in natural conditions and conditions disturbed by the water abstraction. In our study we try to contribute to further understanding the dynamics of groundwater mixing with river water in the hyporheic exchange zone. We focus on understanding river/aquifer interactions at the scale of reach of an intake, especially the unidirectional water flows induced by water abstraction. To understand these issues, a two‐day field hydrogeological experiment was conducted based on a pumping test of increasing intensity. At each pumping stage, groundwater and river samples were collected to determine the concentration of noble gases, CFCs, SF6, stable isotope content, and the chemical composition of the water. The study results indicate a short pressure propagation time (of the order of several hours) between the intake and the river, which already results in the inflow of water from the river–aquifer mixing zone at low rates of water abstraction by the intake. As pumping rates increase, the conditions of mixing and inflow of water to individual wells stabilize or approach stabilized conditions in less than 1–2 days. The share of river water in the water flux flowing into the intake does not exceed 12%, whereas the ratio of river water to groundwater in the mixing zone is estimated at 1 to 7 or more. The range of the river‐aquifer mixing zone may reach up to 170 m from the river and this range can be identified with a good approximation as coinciding with the range of the zone of hyporheic exchange in the study area.

Simulation Study on the Environmental Impact of Rare Earth Ore Development on Groundwater in Hilly Areas: A Case Study in Nuodong, China

Mineral extraction can significantly affect the groundwater flow and hydrochemical environment. However, for hilly areas, significant ground elevation changes and complex geological conditions make it difficult to accurately analyze and predict the impact of mineral mining. This study takes the Nuodong rare earth mining area as an example. Based on field investigations and experiments, GOCAD software (version 2022) was used to establish a geological model in combination with GMS numerical simulation software, which was used to build a groundwater flow model and a solute transport model. The flow model in the hilly area indicated that the absolute error between the simulated and measured water levels of each observation well is 0.554 m. The solute-transport model showed that the maximum pollutant concentration of ammonia-nitrogen (NH3-N) in the liquid injection area, stream area, and village area monitoring wells reaches 139.15, 27.9, and <0.5 mg/L, respectively. During the mining period, streams in the area are affected by NH3-N, which threatens the safety of the water for mine area residents. To control pollutant transport, two stages of pumping were adopted to reduce NH3-N concentrations in groundwater. After adopting the first stage, the peak concentration of the stream area monitoring wells decreased significantly, with the maximum peak concentration decreasing from 27.9 mg/L to 5.51 mg/L. Based on the results of the first stage of the pump-out treatment, a second stage was adopted. The model results showed that the peak concentration of NH3-N pollutants discharged into the stream is less than 0.5 mg/L. The results provide a theoretical basis and reference for groundwater monitoring and pollution control after mining in this area.

Effect of Impeller Trimming on the Energy Efficiency of the Counter-Rotating Pumping Stage

Developing ways to increase centrifugal pumps’ pressure and power characteristics is a critical problem in up-to-date engineering. There are many ways to resolve it, but each has advantages and flaws. The presented article aimed to ensure higher energy efficiency indicators by using a counter-rotating pumping stage with trimming. During the research, the comprehensive approach was based on CFD modeling and the Moore–Penrose pseudoinverse approach for overestimated systems. According to the obtained data, pumps with a counter-rotating stage allowed the pressure head to be significantly increased compared with the standard design of the flow part. Notably, for pumping units CPS 180/1900 with a basic stage, the pressure head of 127 m was reached. However, when using a counter-rotating stage, the pressure head could be increased up to 270 m, which was 2.1 times higher. Therefore, to ensure unchanged characteristics when using centrifugal pumps with the counter-rotating stage, the weight and size indicators can be significantly reduced compared to the traditional design scheme. The proposed numerical and analytical approaches allow estimating the highest pressure and energy characteristics values.

Absolute photon power measurements at the European XFEL instruments

The average photon flux is one of the main parameters of any photon source. At the European XFEL (EuXFEL), this is continuously monitored in the tunnels by X-ray Gas Monitors (XGMs) [1-3]. However, to measure the absolute value of the X-ray flux at the sample location in the scientific end-stations, in general a smaller device is required since the XGMs and their associated differential pumping stages are very space demanding. Therefore, a miniature solid-state room-temperature calorimeter based on a design by AIST, Japan [4-8] was commissioned with beam at the Spectroscopy and Coherent Scattering (SCS) instrument where it could be located directly downstream of an XGM. This allowed for validation of the gas-based measurements with a solid-state physics method with an independent absolute calibration. The calorimeter was then applied at the High Energy Density (HED) instrument to characterize the beamline transmission and to calibrate a commercial laser power meter (LPM) [9] as a secondary relative monitor for X-ray measurements. This contribution describes the technical parameters and capabilities of the calorimeter and LPM and presents the measurements taken at SCS and HED.

Mud pumping in high-speed railway: in-situ soil core test and full-scale model testing

Mud pumping induced by moving train loads on rainwater-intruded roadbed causes intensive track vibrations and threatens safety of high-speed trains. In this paper, a vehicle–track–subgrade finite element model was established to analyze the dynamic responses of a ballastless track, and results showed that the concrete base and roadbed were detached because of the whipping effect arising from the rainwater intrusion channel. An in-situ soil core test showed that the intruded rainwater accumulated in roadbed to form standing water and saturated the roadbed. The flapping action of the concrete base caused by the whipping effect led to mud formation mixed with fine particles and rainwater, which migrated upward under the pore-water pressure (PWP) gradient. Mud pumping resulted from continuous particle migration in the saturated roadbed under moving train loads: under normal roadbed condition, coarse and fine particles were uniformly distributed in the roadbed; in early period of mud pumping, fine particles migrated downward to bottom of the roadbed because of the rainwater infiltration flow; in middle stage of mud pumping, fine particles migrated upward and gathered at the roadbed surface under PWP gradient; in later period of mud pumping, fine particles were entrained and removed with the dissipation of excess PWP. Moreover, a full-scale physical model was established to reproduce mud pumping, and polyurethane injection remediation against mud pumping was validated on this physical model. The remediation method was applied to an in-situ mud pumping. The deviation of the vertical track profile reduced remarkably and remained at a low level within half a year, showing a good long-term service performance of the polyurethane remediated roadbed.

Improved Evaluation of BBR and Collisional Frequency Shifts of NIM-Sr2 with 7.2 × 10−18 Total Uncertainty

NIM-Sr2 optical lattice clock has been developed on the Changping campus of National Institute of Metrology (NIM). Considering the limitations in NIM-Sr1, several improved parts have been designed including a differential pumping stage in the vacuum system, a permanent magnet Zeeman slower, water-cooled anti-Helmholtz coils, an extended viewport for Zeeman slower, etc. A clock laser with a short-time stability better than 3 × 10−16 is realized based on a self-designed 30-cm-long ultra-low expansion cavity. The systematic frequency shift has been evaluated to an uncertainty of 7.2 × 10−18, with the uncertainty of BBR shift and the collisional frequency shift being an order of magnitude lower than the last evaluation of NIM-Sr1.