Faster Closure Research Articles

Bioactive Hydrogel Supplemented with Stromal Cell-Derived Extracellular Vesicles Enhance Wound Healing

Background/Objectives: Skin regeneration is a rapidly advancing field with significant implications for regenerative medicine, particularly in treating wounds and burns. This study explores the potential of hydrogels functionalized with fibroblast-derived extracellular vesicles (EVs) to enhance skin regeneration in vivo. Being immunoprivileged, EVs minimize immune rejection, offering an attractive alternative to whole-cell therapies by replicating fibroblasts’ key roles in tissue repair. Methods: To promote EVs’ versatility and effective application across different conditions, a lyophilization method with lyoprotectants was optimized. Then, EVs were used to functionalize a hydrogel to perform experiments on murine cutaneous wound models. Results: Gelatin methacrylate (GelMA) was selected as the polymeric hydrogel due to its biocompatibility, tunable mechanical properties, and ability to support wound healing. Mechanical tests confirmed GelMA’s strength and elasticity for this application. Fibroblast-derived EVs were characterized using Western blot, Transmission Electron Microscopy, and NanoSight analysis, proving their integrity, size distribution, and stability. miRNome profiling identified enriched biological pathways related to cell migration, differentiation, and angiogenesis, emphasizing the critical role of EV cargo in promoting wound repair. In a murine model, hydrogels loaded with fibroblast-derived EVs significantly accelerated wound healing compared to controls (mean wound area 0.62 mm2 and 4.4 mm2, respectively), with faster closure, enhanced epithelialization, increased vascularization, and reduced fibrosis. Notably, the lyoprotectants successfully preserved the EVs’ structure and bioactivity during freeze-drying, reducing EVs loss by 35% compared to the control group and underscoring the feasibility of this approach for long-term storage and clinical application. Conclusions: This study introduces a novel scalable and adaptable strategy for regenerative medicine by combining fibroblast-derived EVs with GelMA, optimizing EVs’ stability and functionality for enhanced wound healing in clinical settings, even in challenging contexts such as combat zones or large-scale natural disasters.

Transient Flow in Pressurized Pipes: A Comparative Study of Five Resolution Methods

Abstract This article solves, models, and simulates, by five different methods, the system of partial differential equations of hyperbolic type governing the transient flow in the case of a gravity pipe supplied from a reservoir and equipped with a valve at its extremity. To make this work smoother and more attractive when calculating hydraulic parameters in transient flow, we took into consideration the two valve closing laws most commonly used in practice and in case of fast and slow closing. The reliability and safety of operation of the pressure pipeline system (PPS) depends on protection systems against the harmful effects of transient flow. To be able to place the most suitable protection device where it is needed, we must use numerical methods to model and simulate such processes. To this end, we applied five methods to solve the transient flow equations and subsequently search for the method giving results with practical credibility. The results obtained show that the methods of MarcCormak and Alternative lead, in fast and slow closures, to very close values by giving more logical graphic representations to the phenomenon generated. The Lax-Friedrichs method can join them but with another appearance of the representation of pressures, and the method of characteristics neglects certain parameters such as the inclination of the pipe while the Richtmayer method should be avoided in its current form because of the error gap between it and the other methods, and the graphical representation of the results obtained, like the pressure over time, which does not give a logical interpretation of the phenomenon produced.

Impact of Aggregatibacter actinomycetemcomitans on epithelial repair

ABSTRACT: Normal wound healing occurs in four overlapping stages - hemostasis, inflammation, proliferation, and remodeling. In the oral cavity, these processes occur in an infectious environment. Among the pathogens found in the oral community, Aggregatibacter actinomycetemcomitans (Aa) constitutes a well-recognized periodontal pathogen responsible for expressing several virulence factors, which activate a host response. Aim: This study investigated whether Aa’s presence can interfere with oral keratinocyte tissue healing in an in vitro wound healing model. Methods: Two groups were defined: Group KO (n=5) and Group KO+Aa (n=5). The Aa (JP2 strains) were cultivated in anaerobiosis, and the total protein extract was obtained. The keratinocytes were cultivated with the medium of standard culture until their confluence. After confluence, plates were allocated to each group. With the pipette’s tip, a “scratch” was made in the middle of each well of the plate, and the cells were cultured at 37°C in a humidified atmosphere with 5% CO2. The cells received the stimulus according to groups, and, at times 0, 5, 10, 24, and 48 hours, the wound areas were visualized and standardly recorded using an inverted microscope. Results: When analyzing the timeframe, differences in wound measurements indicate a faster closure in the control group compared to the KO+Aa group, although not statistically significant. However, upon examining the wound closure measures, it was observed that the Aa protein extract significantly reduced wound closure at 10 and 48 hours (p<0.05), negatively impacting the keratinocyte’s behavior. Conclusion: In summary, it was demonstrated that the pathogen Aa can interfere with the re-epithelization in vitro.

A novel reopenable clip with sharp claw for complete closure of mucosal defects after colorectal endoscopic submucosal dissection.

The MANTIS Closure Device (MCD; Boston Scientific, Marlborough, Massachusetts, USA) is a reopenable clip with a sharp claw used for closure after endoscopic submucosal dissection (ESD). We evaluated the effectiveness of the MCD for fast and complete closure after colorectal ESD. Cases involving closure with the MCD after ESD of 20-60-mm colorectal lesions between April 2023 and January 2024 were reviewed. The primary end point was complete closure of the ESD defect with the MCD. Secondary end points included closure time, delayed bleeding, delayed perforation, and post-ESD coagulation syndrome (PECS). MCD application involved: 1) grasping the mucosa on the anal-side of the defect; 2) pushing the clip toward the oral-side mucosa and deploying it; 3) adding other reopenable clips for complete closure. 61 cases involving MCD were analyzed. Mean tumor size was 32.3 (SD 9.2) mm. Complete closure rate was 98.4% and mean closure time was 6.9 (SD 2.6) minutes. The mean number of MCDs and other clips used was 1.0 (SD 0.1) and 4.7 (SD 1.4), respectively. Rates of delayed bleeding, delayed perforation, and PECS were 0%, 0%, and 9.8%, respectively. Fast and complete closure after colorectal ESD was successfully achieved using the MCD.

High-speed aerial grasping using a soft drone with onboard perception

Contrary to the stunning feats observed in birds of prey, aerial manipulation and grasping with flying robots still lack versatility and agility. Conventional approaches using rigid manipulators require precise positioning and are subject to large reaction forces at grasp, which limit performance at high speeds. The few reported examples of high-speed aerial grasping rely on motion capture systems, or fail to generalize across environments and grasp targets. We describe the first example of a soft aerial manipulator equipped with a fully onboard perception pipeline, capable of robustly localizing and grasping visually and morphologically varied objects. The proposed system features a novel passively closed tendon-actuated soft gripper that enables fast closure at grasp, while compensating for position errors, complying to the target-object morphology, and dampening reaction forces. The system includes an onboard perception pipeline that combines a neural-network-based semantic keypoint detector, a state-of-the-art robust 3D object pose estimator, and a fixed-lag smoother to estimate the pose of known objects. The resulting pose estimate is passed to a minimum-snap trajectory planner, tracked by an adaptive controller that fully compensates for the added mass of the grasped object. Finally, a finite-element-based controller determines optimal gripper configurations for grasping. Experiments on three different targets confirm that our approach enables dynamic, high-speed, and versatile grasping, all of which are necessary capabilities for tasks such as rapid package delivery or emergency relief. We demonstrate fully onboard vision-based grasps of a variety of objects, in both indoor and outdoor environments, and up to speeds of 2.0 m/s—the fastest vision-based grasp reported in the literature. Finally, we take a major step in expanding the utility of our platform beyond stationary targets, by demonstrating motion-capture-based grasps of targets moving up to 0.3 m/s, with relative speeds up to 1.5 m/s.

Fast loop closure detection using probabilistic integration of pose and appearance similarity

Loop closure detection is a key technique for robots to minimize the accumulated localization and mapping errors after long-time explorations of simultaneous localization and mapping. However, the requirement for efficiency and accuracy performance for mobile robot applications is not well satisfied. In this article, we propose a fast and accurate loop closure detection method by exploiting both pose-based and appearance-based information in a probabilistic manner, inspired by the complementarity between the pose-based and the appearance-based information. Our approach formulates a probability framework combing the pose-based loop closure detection probability and the appearance-based loop closure detection probability. In the proposed framework, the pose-based loop closure detection model is firstly derived from the nonlinear optimization model of odometry. Then the appearance-based loop similarity and the pose-based loop similarity are combined into a joint framework to improve the loop closure detection performance. We implemented our approach using C++ and ROS and thoroughly tested it on the publicly available datasets. The experiments presented in this article suggest that the proposed method can achieve high efficiency and accuracy performance on loop closure detection.

Investigation Of The Influence Of The Turbine Wicket Gates Closure Law Pattern On The Water Hammer Effect During Turbine Off-Design Operation

Hydraulic transients are accelerated by the wicket gate closing in hydroelectric power plants. When the wicket gate is closed, there is a sudden change in velocity due to the closure. Therefore, a study has been carried out here, wherein water hammers on different hydropower components use optimum closure laws: Fast closure laws, slow closure laws, and instant load rejection. Hammer V10i software was used to investigate the phenomenon of pressure transient. The results show that the maximum transient pressure is strongly influenced by a very short closing time and was increased to 41.24% from the slow to the fast closure.
 Furthermore, the results from instant load rejections reveal that the transient pressure will be less than the fast and slow closure. So, the closing law selection can positively influence the entire hydropower plant system. Furthermore, the results show that there was a decrease in pressure near the turbine during the different load rejections, Fast closure, slow closure, and instant load rejection, where 57.7%, 15%, and 0.46%, respectively, and the decrease in turbine rotation speed were as 5.1%, 60%, and 24% respectively. Moreover, results reveal that maximum and minimum flow variation reached -29.75% and 41.2% during the fast closure.
 

Mutation in Arabidopsis mitochondrial Pentatricopeptide repeat 40 gene affects tolerance to water deficit

Main ConclusionThe Arabidopsis Pentatricopeptide repeat 40 (PPR40) insertion mutants have increased tolerance to water deficit compared to wild-type plants. Tolerance is likely the consequence of ABA hypersensitivity of the mutants.Plant growth and development depend on multiple environmental factors whose alterations can disrupt plant homeostasis and trigger complex molecular and physiological responses. Water deficit is one of the factors which can seriously restrict plant growth and viability. Mitochondria play an important role in cellular metabolism, energy production, and redox homeostasis. During drought and salinity stress, mitochondrial dysfunction can lead to ROS overproduction and oxidative stress, affecting plant growth and survival. Alternative oxidases (AOXs) and stabilization of mitochondrial electron transport chain help mitigate ROS damage. The mitochondrial Pentatricopeptide repeat 40 (PPR40) protein was implicated in stress regulation as ppr40 mutants were found to be hypersensitive to ABA and high salinity during germination. This study investigated the tolerance of the knockout ppr40-1 and knockdown ppr40-2 mutants to water deprivation. Our results show that these mutants display an enhanced tolerance to water deficit. The mutants had higher relative water content, reduced level of oxidative damage, and better photosynthetic parameters in water-limited conditions compared to wild-type plants. ppr40 mutants had considerable differences in metabolic profiles and expression of a number of stress-related genes, suggesting important metabolic reprogramming. Tolerance to water deficit was also manifested in higher survival rates and alleviated growth reduction when watering was suspended. Enhanced sensitivity to ABA and fast stomata closure was suggested to lead to improved capacity for water conservation in such environment. Overall, this study highlights the importance of mitochondrial functions and in particular PPR40 in plant responses to abiotic stress, particularly drought.

Learning fast, accurate, and stable closures of a kinetic theory of an active fluid

Learning fast, accurate, and stable closures of a kinetic theory of an active fluid

Numerical Simulation of Corrugated Steel Concrete Prefabricated Support Structure for Underground Engineering

The spray anchor system is commonly used for primary support in underground projects due to its advantages such as fast closure of excavation surfaces, tight connection with the surrounding rock, and high early strength. However, this system has several drawbacks, such as severe pollution, poor working conditions, long construction periods, and high labor costs. In response to the concepts of green construction and prefabrication, this study proposes an innovative composite structure consisting of corrugated steel plates and concrete, namely, corrugated steel–concrete (CSC), which is a prefabricated support structure for underground engineering. The proposed system involves on-site corrugated steel plates and concrete, and the concrete is poured into the corrugated steel plates without using shotcrete. This approach mitigates pollution and improves working conditions. After the introduction to the novel structural system, elaborate Abaqus numerical models are developed to investigate the mechanical performance considering full elastoplastic response until failure. The steel–concrete interfacial connections, as a major factor in composite structures, are carefully studied and discussed based on the delicate interfacial contact model. The deformations, stress distributions, and failure types are analyzed. A parametric analysis is also conducted to expand the efficient range. Theoretical analysis is further carried out, and design expressions are proposed, which are verified to be suitable for design considerations.

Enhancing rice resilience to drought by applying biochar–compost mixture in low-fertile sandy soil

BackgroundClimate change alters modern drought episode patterns by making them longer, more frequent and more severe, in particular in arid and semi-arid agroecosystems. Amending soil properties and enhancing its fertility is a needed sustainable strategy for mitigating drought’s damaging effects on crop production and food security. Here, we planned to investigate the potential benefits of biochar–compost mixture (B×C) as a biochar-based fertilizer (BCF) in enhancing the drought tolerance of rice plants cultivated in low-fertile sandy soil.ResultsUnder drought stress, rice plants cultivated in unamended soil (no B×C) exhibited severely wilted, rolled and discolored shoots. Furthermore, the shoot dry biomass reduction ratio was 73.3% compared to 44.2 and 27.6% for plants treated with 5 and 15% B×C, respectively. Root anatomical and architectural traits were significantly less impaired in B×C plants and reflected better performance under drought compared to no B×C plants. During the induced drought episode, soil moisture content was enhanced by 2.5-fold through adding B×C, compared to unamended soil, thereby reducing the negative impact of drought stress. Moreover, the less drought-stressed rice plants (B×C-treated) rapidly recovered after rewatering and displayed the unwinding of previously rolled leaves and reproduced panicles. On the other hand, no B×C plants failed to recover and eventually perished completely. The expression profiles of several drought responsive genes suggest that leaves of more stressed rice plants (no B×C) significantly accumulated more cytosolic free calcium (OsCML3) and apoplastic H2O2 (OsOXO4) which eventually may trigger fast and prolonged stomatal closure (OsSRO1c). In addition, more drought-stressed plants (no B×C) may over-produce the reactive oxygen species (ROS) superoxide anion molecules (OsRbohB), the negative situation that has been further complicated by a possible reduction in the activity of the antioxidative enzyme SOD (OsSOD), and thus more lipid peroxidation (3.5-fold increase MDA) in drought-stressed (no B×C) plant shoots compared to B×C plants.ConclusionIt is suggested that soil amendment B×C (biochar–compost mixture) could promote drought stress tolerance in rice plants by retaining more soil moisture content, thereby mitigating the negative effects of drought stress, such as the over-production of ROS in leaves, and thus eventually facilitating recovery after rewatering.

Procedural Promotion of Wound Healing by Graphene-Barium Titanate Nanosystem with White Light Irradiation.

Wound healing is a continuous and complex process that comprises multiple phases including hemostasis, inflammation, multiplication (proliferation) and remodeling. Although a variety of nanomaterials have been developed to control infection and accelerate wound healing, most of them can only promote one phase but not multiple phases, resulting in lower efficient healing. Although various formulations such as nitric oxide releasing wound dressings were developed for dual action, the nanostructure synthesis and the encapsulation process were complex. Here, we report on the design of graphene-barium titanate nanosystem to procedural promote the wound healing process. The antibacterial effect was assessed in Gram-negative Escherichia coli bacteria (E. coli) and Gram-positive Staphylococcus aureus bacteria (S. aureus), the cell proliferation and migration experiment was investigated in mouse embryonic fibroblast (NIH-3T3) cells, and the wound healing effect was analyzed in female BALB/c mice with infected skin wound on the back. Results showed that graphene-barium titanate nanosystem could generate abundant ROS to kill both E. coli and S. aureus. The growth curves, bacterial viability, colony number formation and scanning electron microscopy (SEM) images of E. coli and S. aureus all confirmed the antibacterial effect. Cell Counting Kit-8 (CCK-8) assay displayed that GBT possesses great biocompatibility. EdU assay showed that GBT plus white light irradiation significantly promoted the proliferation and migration of NIH-3T3 cells. Scratch assay found that GBT could achieve a fast scratch closure compared to the control. In vivo wound healing effect indicates that GBT can accelerate wound repair procedure. GBT nanocomposite is capable of programmatically accelerating wound healing through multiple stages, including production of a large amount of ROS after white light exposure to effectively kill E. coli and S. aureus to prevent wound infection and as a scaffold to accelerate fibroblast proliferation and migration to the wound to accelerate wound healing.

Cavitation evolution and flow field characteristics of transient flows with multi-point water-column separations in undulating pipeline

Transient flows with water-flow-induced multi-point cavitation inside an undulating pipeline are investigated experimentally under conditions of fast valve closure for three typical test cases by using high-precision pressure transducers, high-speed photography and particle image velocimetry (PIV) techniques. For low initial velocity condition, the transient pressure at the monitoring point (PT1) downstream the valve quickly decreases to the cavitation pressure and fluctuates near it. The leading-edge velocity of the dispersed bubble-like cavitation group first increases with its occurrence and then accelerates and reaches an extreme value before decreasing to zero due to the viscous force and the decrease of water flow inertia, and finally the water flows upstream in reverse, i.e. the leading-edge accelerates and collapses behind the valve. At the same time, the transient pressure rises sharply to maximum 81.86 m due to the return of the compression wave and then decreases sharply to cavitation again because of the switch of the pressure waves. Then, the second cavitation intensity is weak and the corresponding pattern is fog-like, and finally decreases gradually with a cyclic period of about 0.38 s. The transient pressure at the monitoring point (PT2) at the peak of the undulating pipeline also maintains at the cavitation pressure corresponding to the big bubble occurrence moment in addition to its fluctuation near the cavitation pressure including first and second cavitation. Its maximum pressure is 72.16 m and the corresponding cavitation pattern is small and bigger bubbles at different cavitation stages. For middle initial velocity, the typical pattern of the corresponding cavitation is the large cavity with free surface at PT2, the corresponding higher maximum pressures are 102.36 m at PT1 and 84.81 m at PT2. The evolution process of the cavity including bubble mergence, morphological deformation, motion and collapse is analysed based on the broken wave and hydraulic dynamic theories. For high initial velocity, larger cavities occur both downstream the valve and at the peak point of undulating pipeline, and thus the corresponding higher maximum pressures due to larger cavity collapse are 140.56 m at PT1 and 127.98 m at PT2. In particular, complete water column separation with transparent large cavity occur downstream the valve.

Flexible Organic Electronic Ion Pump for Flow-Free Phytohormone Delivery into Vasculature of Intact Plants.

Plant vasculature transports molecules that play a crucial role in plant signaling including systemic responses and acclimation to diverse environmental conditions. Targeted controlled delivery of molecules to the vascular tissue can be a biomimetic way to induce long distance responses, providing a new tool for the fundamental studies and engineering of stress-tolerant plants. Here, a flexible organic electronic ion pump, an electrophoretic delivery device, for controlled delivery of phytohormones directly in plant vascular tissue isdeveloped. The c-OEIP is based on polyimide-coated glass capillaries that significantly enhance the mechanical robustness of these microscale devices while being minimally disruptive for the plant. The polyelectrolyte channel is based on low-cost and commercially available precursors that can be photocured with blue light, establishing much cheaper and safer system than the state-of-the-art. To trigger OEIP-induced plant response, the phytohormone abscisic acid (ABA) in the petiole of intact Arabidopsis plantsis delivered. ABA is one of the main phytohormones involved in plant stress responses and induces stomata closure under drought conditions to reduce water loss and prevent wilting. The OEIP-mediated ABA delivery triggered fast and long-lasting stomata closure far away from the delivery point demonstrating systemic vascular transport of the delivered ABA, verified delivering deuterium-labeled ABA.

DYSCALCULIA, a Venus flytrap mutant without the ability to count action potentials

The Venus flytrap Dionaea muscipula estimates prey nutrient content by counting trigger hair contacts initiating action potentials (APs) and calcium waves traveling all over the trap.1,2,3 A first AP is associated with a subcritical rise in cytosolic calcium concentration, but when the second AP arrives in time, calcium levels pass the threshold required for fast trap closure. Consequently, memory function and decision-making are timed via a calcium clock.3,4 For higher numbers of APs elicited by the struggling prey, the Ca2+ clock connects to the networks governed by the touch hormone jasmonic acid (JA), which initiates slow, hermetic trap sealing and mining of the animal food stock.5 Two distinct phases of trap closure can be distinguished within Dionaea's hunting cycle: (1) very fast trap snapping requiring two APs and crossing of a critical cytosolic Ca2+ level and (2) JA-dependent slow trap sealing and prey processing induced by more than five APs. The Dionaea mutant DYSC is still able to fire touch-induced APs but does not snap close its traps and fails to enter the hunting cycle after prolonged mechanostimulation. Transcriptomic analyses revealed that upon trigger hair touch/AP stimulation, activation of calcium signaling is largely suppressed in DYSC traps. The observation that external JA application restored hunting cycle progression together with the DYSC phenotype and its transcriptional landscape indicates that DYSC cannot properly read, count, and decode touch/AP-induced calcium signals that are key in prey capture and processing.

Variations in OsSPL10 confer drought tolerance by directly regulating OsNAC2 expression and ROS production in rice.

Drought is a major factor restricting the production of rice (Oryza sativa L.). The identification of natural variants for drought stress-related genes is an important step toward developing genetically improved rice varieties. Here, we characterized a member of the SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) family, OsSPL10, as a transcription factor involved in the regulation of drought tolerance in rice. OsSPL10 appears to play a vital role in drought tolerance by controlling reactive oxygen species (ROS) production and stomatal movements. Haplotype and allele frequency analyses of OsSPL10 indicated that most upland rice and improved lowland rice varieties harbor the OsSPL10Hap1 allele, whereas the OsSPL10Hap2 allele was mainly present in lowland and landrace rice varieties. Importantly, we demonstrated that the varieties with the OsSPL10Hap1 allele showed low expression levels of OsSPL10 and its downstream gene, OsNAC2, which decreases the expression of OsAP37 and increases the expression of OsCOX11, thus preventing ROS accumulation and programmed cell death (PCD). Furthermore, the knockdown or knockout of OsSPL10 induced fast stomatal closure and prevented water loss, thereby improving drought tolerance in rice. Based on these observations, we propose that OsSPL10 confers drought tolerance by regulating OsNAC2 expression and that OsSPL10Hap1 could be a valuable haplotype for the genetic improvement of drought tolerance in rice.

Modified pericostal suture technique to reduce postoperative pain and provide optimum anatomic restoration after conversion of minimally invasive thoracic surgery to thoracotomy.

Minimally invasive thoracic techniques often need to be converted to open thoracotomy. Thoracotomy is associated with severe postoperative pain in 50% of the patients, and this situation can be maintained for a prolonged period. Many efforts have been made to avoid this complication. We propose an easy and fast thoracotomy closure technique to avoid nerve entrapment at the time of chest closure suitable for cases of conversion to thoracotomy after a minimally invasive attempt. The proposed method effectively avoids interference with the intercostal nerve, which remains intact and restores the anatomy of the intercostal space. Efforts to decrease postoperative pain are vital. Thoracic surgeons are the principal health professionals able to deal with operative factors and postoperative pain management. We believe that the use of this easy and fast technique can facilitate excellent anatomic repositioning of the ribs alongside nerve sparing.

Corrigendum for “Fast and incremental loop closure detection with deep features and proximity graphs”

Corrigendum for “Fast and incremental loop closure detection with deep features and proximity graphs”

Consumption Change‐Induced Transients in a Water Distribution Network: Laboratory Tests in a Looped System

AbstractAt the Water Engineering Laboratory of the University of Perugia, Italy, a wide experimental program has been carried out in a polymeric pipe network with two 100 × 100 m square loops. The aim of this program is to analyze the dynamic response of the system to transients caused by a change in water consumption. To emphasize such a response, transients are generated by the complete and fast closure of an end‐user, located at the downstream end of a service line. During tests, the combined effect of simultaneous consumers, whose consumption is varied both deterministically and stochastically, has been analyzed. The tests allow examining the propagation of the generated pressure waves within the network for different water consumption variations and end‐user locations. The lessons learnt from the experimental results may help the water utility managers to identify the reasons for the higher frequency of occurrence and severity of faults in some specific portions of water distribution networks apparently “similar” to others where damages are less frequent and severe.

A Quick Survey of the Most Vulnerable Areas of a Water Distribution Network Due to Transients Generated in a Service Line: A Lagrangian Model Based on Laboratory Tests

This paper analyses the propagation and mechanisms of interaction of a pressure wave in a looped water distribution network by means of laboratory and numerical tests. Transients are generated by the complete and fast closure of a valve, simulating an end-user maneuver, located at the downstream end section of a service line. The adequate length of the service line allows capturing each single pressure wave inserted into the network. The executed tests and successive analysis by means of a Lagrangian model (LM) highlight the effect of the network topology and the location of the transient generation point but in a more expeditious way with respect to the use of a complete transient model. The most excited part of the system is the one in close proximity of the end-user and then the corresponding service line. Within the network, pressure waves accumulate in the areas with the smallest diameter pipes. By means of the refined LM—which is able to capture the pressure extreme values occurring in the first phases of the transient—the vulnerability maps of the network are provided. Such maps identify the nodes subjected to the most severe pressure waves in terms of both frequency and amplitude. The exposure level to transients of each node is synthesized by the value of the vulnerability index proposed in this paper.