Bed Level Research Articles

Influence of outlet keys slope on downstream bed topography in trapezoidal piano key weirs: An experimental investigation

Assessing scour depth downstream of piano key weirs (PKWs) is crucial for maintaining their structural integrity. The slope of the outlet keys significantly influences flow velocity and the associated risk of downstream scouring. This study experimentally investigates the impact of various factors on scour downstream of trapezoidal PKWs, specifically focusing on weir outlet keys slope (So), particle Froude number, sediment size, bed levels, and relative drop height. The research identifies three distinct stages of scouring. Notably, changes in So significantly affect the hydraulic flow over both the inlet and outlet keys. Reducing So by 57 % led to increases of approximately 32 %, 34 %, 49 %, and 54 % in relative maximum scour depth, distance from the weir, length, and volume of the scour hole, respectively, while relative weir toe scour decreased by about 31 %. Additionally, a decrease in So shifted the locations of the maximum scour depth and sediment ridge downstream, enhancing the symmetry of the scour hole. Increasing the particle Froude number and relative drop height, along with decreasing tailwater depth and sediment size, further intensified the scour hole and sediment ridge characteristics. This study provides critical insights for mitigating downstream scouring in PKWs through a comprehensive analysis of varying So. The proposed optimal value for So, along with newly developed design equations, offers practical guidance for engineers and water resource managers in enhancing the stability of hydraulic structures.

Changes in platelet transfusion thresholds utilized in the NICU since PlaNeT-2

Abstract Background Use of prophylactic platelet transfusions in the neonatal setting is a common practice due to concerns about bleeding despite evidence of a developmental mismatch with transfusion of adult platelets. The Platelets for Neonatal Transfusion-Study 2 (PlaNeT-2) published in January 2019 showed that using higher platelet thresholds (50 x 109/L) was associated with more adverse outcomes and no improvement in bleeding events compared to lower platelet thresholds (25 x 109/L). Following this trial, implementation of a lower threshold was provider dependent as there were no changes made to the neonatal intensive care unit (NICU) institutional policies. Our goal was to determine if there were any overall changes in individual clinical practice with thresholds used for platelet transfusions in our NICU and number of transfusions per patient. Methods Our center has a 52 bed level IV NICU that specializes in care for critical and/or preterm infants. We performed a retrospective review from 2017 to 2023 of patients admitted in the NICU who received platelet transfusion and had an available platelet count in the 12 hours prior to the transfusion. Results There were 272 platelet transfusions given to 107 unique NICU patients who had platelet counts available. There were 66 transfusions given to 32 patients pre-PlaNeT-2 (2017-2018) and 206 transfusions given to 75 patients post-PlaNeT-2 (2019-2023). The average platelet count pre-PLaNeT-2(2017 to 2018) was 43 x 109/L (SD±24 x 109/L) and post-PLaNeT-2 (2019 to 2023) was 36 x 109/L (SD±21 x 109/L, p=0.03). Prior to PLaNeT-2, 26% of platelet transfusions were for platelet counts ≤ 25 x 109/L and 35% were for platelet counts between 51 to 100x9/L. Post PLaNeT-2 the percentages changed to 35% and 21% respectively. The percentage of transfusions occurring for platelet counts between 26 to ≤50 x 109/L was 38% and 44%, respectively. The number of platelet transfusions per year did not decrease significantly after the PLaNeT-2 trial (average of 33/year versus 41/year, p=0.5). The number of transfusions per patient before and after PLaNeT-2 did not change (2.1 transfusions per patient versus 2.6 transfusions per patient, p=0.3). Conclusion Platelet thresholds utilized in our center decreased after the PLaNeT-2 trial with less transfusions occurring for platelet counts greater than 50 x 109/L. Although thresholds decreased, the number of transfusions per year and the number of transfusions per patient did not significantly change. Further studies are needed to understand changes in patient outcomes and platelet utilization in the NICU.

Perfusion computer tomography of the kidneys. Research technique. Perfusion indicators in the norm: case-control

INTRODUCTION: Perfusion computed tomography (PCT) is a contrast research technique that allows one to assess blood flow in the cortical and medulla layers of the renal parenchyma at the level of the microcirculatory bed, the influence of additional renal vessels and stenoses of the renal arteries on hemodynamics in the renal parenchyma.OBJECTIVE: To optimize the technique of perfusion computed tomography of the kidneys. Determine the most informative indicators of perfusion in the renal parenchyma in the norm. Assess the relationship between perfusion parameters and the number of renal vessels, the presence of renal artery stenosis.MATERIALS AND METHODS: PCT was performed in 46 patients with no anamnestic and clinical laboratory data on kidney disease who were undergoing examination for other pathological conditions, including 35 patients aged from 20 to 90 years (average age — 63.1 years) without hemodynamically significant stenosis and 11 patients aged from 64 to 94 years (mean age 80.3 years) with renal artery stenosis of 50% or higher. Perfusion indices were calculated using maximum slope and deconvolution algorithms, kinetic curves were plotted on a time-density graph, and color parametric maps.RESULTS: A quantitative assessment of perfusion parameters in the cortical and medulla of the kidneys, a qualitative analysis of the state of its parenchyma on color parametric maps, and the shapes of kinetic curves on the time-density graph were analyzed. Changes in perfusion parameters were established depending on the age, number and condition of the renal vessels.DISCUSSION: In the renal cortical layer, there was a predominance of indicators of blood flow velocity (BF), blood flow volume (BV), the rate of increase in the density of the contrast agent (CM) in the tissue (MSI), capillary wall permeability (PS) and lower values of the average transit time of the contrast agent (MTT) and the time to reach the maximum contrast agent density in the tissue (TTP) in comparison with the medulla. On the color parametric maps BF, BV, MSI, the cortical layer was characterized by intense red coloring, the medulla — yellow-green, on the TTP map green and blue coloring of the layers was determined, respectively. In elderly patients, there was a decrease in BF, BV with a concomitant lengthening of TTP in the cortical layer without changes in coloring on color parametric maps. On the density-time graph, the kinetic curve of the cortical layer was characterized by the appearance of a peak 10 seconds after the onset of the peak value in the abdominal aorta with further continuation of the curve in the form of a plateau; the kinetic curve of the medulla was characterized by a gradual moderate rise in the curve from 15 seconds after the start of scanning without the formation of peaks values.CONCLUSION: PCT is an informative method for quantitative and qualitative assessment of perfusion in the renal parenchyma.

In-field assessment of bridge pier scour by means of Fiber Bragg Gratings: System and algorithms

BLESS (Bed LEvel Seeking System) is a sedimeter that measures riverbed level around bridge pier in water. It is based on Fiber Bragg Gratings and the working principle is based on the measurement of the different heat dissipation behaviour in the saturated soil compared to the flowing water. It is an innovative part of a complex monitoring system installed on a road bridge over the Po river (Italy). After two years of data storage, a comparison of two different methods to detect the riverbed level can be performed. One of them showed results in satisfactory agreement with those provided by a traditional reference device, i.e., an echo sounder. Furthermore, coupling the two different proposed bed level estimation methods allows deriving significant information about the health status of the sedimeter. The device is reliable enough to operate and survive in very harsh environments and it is ready for further engineering applications.

The impact of a storm on the microtidal flat in the Yellow River Delta

Strong hydrodynamic forces generated by storms are key in shaping coastal tidal flats. Most tidal flats achieve equilibrium by adapting to hydrodynamic conditions and sediment inputs. However, high-energy wave activity during storms disrupts this equilibrium, causing rapid and significant changes, particularly in tidal flats, especially in microtidal flats, which are characterized by low tidal ranges. In this study, we conducted an 11-d field campaign on a microtidal flat in the Yellow River Delta (YRD), capturing data during both stormy and calm weather conditions. We measured tidal currents, wave activity, suspended sediment concentrations and sediment grain sizes. The results demonstrated that the tidal flat maintained equilibrium under calm conditions, with minimal fluctuations in bed level (within ±2 mm). Contrastingly, severe erosion and sediment removal during the storm significantly altered the equilibrium of the area. The storm-induced high shear stresses, ranging from 1.02 to 1.48 , along with alongshore sediment transport, resulted in an elevation change of -10 mm. Furthermore, the subsequent bed level recovery was minimal and insufficient to offset the erosion. Compared to that of the mesotidal and macrotidal flats, post-storm recovery on microtidal flats was limited due to shorter inundation periods and weaker hydrodynamic forces. Therefore, frequent storms may lead to continuous shoreline retreat on microtidal coasts. Conclusively, the present findings underscore the significant impact of storm-induced erosion on the evolutionary processes of microtidal flats and suggest that greater attention should be given to protecting these areas during storms in the Yellow River Delta. The insights can guide the development of more effective coastal protection strategies, highlighting the need for enhanced measures to mitigate erosion and promote resilience in microtidal regions.

An Analysis Management by Mike 21 Modelling at Rolak 70 Retention Pool in Jombang Regency, East Java Province, Indonesia

Some areas in Indonesia have high level of sedimentation problems that able to cause flooding, and one apparent solution is to build a retention pool. Sedimentation is deposition of material into the reservoir or dam due to environmental damage or erosion occurs in the river basin area. Sedimentation becomes the main factor in constructing the Rolak 70 Retention Pool, as an important component in controlling floods on the Konto River when the water discharge exceeds the maximum limit. From geography perspective, the modelling location is in waters located between 112° 11′ 22.85″ South Latitude and 7° 38′ 42.23″ East Longitude. The model area has northern boundary at the tip of Rolak 70 pool, while western boundary at the outlet of Rolak 70 pool. The lowest water depth value is located in upstream area of Konto River at coordinates of 112°11’27.81″ South Latitude and 7°38’49.27″ East longitude. Weight of soil sample taken from the research site was ± 1000 grams at each point, and the result of sediment sample test performed at the Soil Mechanics Laboratory of Civil Engineering Department, Sultan Agung University, Semarang showed that the research area is dominated by sand, followed by mud and gravel. There were several tests conducted include grain size analysis, hydrometer analysis, and specific gravity analysis to determine the D50 of the sediment. In the study area, several sampling points were taken, started from upstream area of the river in front of Rolak 70 building to the Rolak 70 Retention Pool. For this purpose, a MIKE 21 software modelling was used to determine distribution and lines of sedimentation in the study area. As visible from changes found in bed level morphology that occurred in Rolak 70 Retention Pool by cross section extraction, it can be seen that the largest change occurred in analysis for line 1 and the smallest bed level changes occurred in the analysis for line 6. Then, the result revealed that sedimentation tends to occur at large locations in upstream area of Rolak 70 Retention Pool, while the smallest sedimentation potential will happen at the downstream area of Rolak 70 Retention Pool. These results can be caused by changes of speed from the river flow which tends to decrease towards the end of Rolak 70 Retention Pool. So, the river flow has no more energy to carry heavy amount of sediments originating from the upstream area of the Konto River. By the existence of this retention pool, the need for rice field irrigation will not be disturbed by sediment deposits. In addition, the Rolak 70 Retention Pool can be used as temporary storage for material from Mount Kelud eruption where these materials can be utilized as building material or other useful purposes.

Regime Shift to Hyperturbid Conditions in the Loire Estuary: Overview of Observations and Model Analysis of Physical Mechanisms

AbstractThe Loire estuary (France) was extensively deepened during the 20th century. Coincidentally, suspended sediment concentrations increased drastically from ∼0.1 g/l to ∼1–5 g/l at the surface and the estuarine turbidity maximum (ETM) moved upstream. In this study we, for the first time, brought together a century of observations of estuary bed level, tidal amplitude, and sediment concentration to demonstrate these large changes. Next, we analyzed a minimal set of physical mechanisms that explain the dramatic increase in sediment concentration. To this end, we used the iFlow model representing dynamic equilibrium conditions in the Loire. Novel in the model is that it dynamically resolves salt stratification and corresponding damping of turbulence. For conditions representing the year 2000, high sediment concentrations were found with satisfactory correspondence to observations. Low sediment concentrations were found when using the year 1900 bed level but keeping all other model parameters the same. Varying the bed level gradually between these two extremes, the equilibrium solution suddenly increases for intermediate bed level, constituting an abrupt regime shift. Robustness of this result was established in an extensive sensitivity study featuring 13,200 model experiments. The regime shift is enabled by a feedback between increasing sediment concentration, reducing turbulence due to sediment and salt stratification, and increasing sediment importing capacity of the estuary. The essential sediment importing mechanisms in this feedback are related to the tidal asymmetry and gravitational circulation. This is the first time gravitational circulation and salt stratification are shown to be important factors in a transition to hyperturbidity.

Biopsychosocial conditions of patients in the rheumatology department of a university hospital.

The aim was to examine biopsychosocial conditions of patients hospitalized in the rheumatology department of a university hospital. Ninety-six patients (mean age: 53.14 ±16.83 years) receiving inpatient treatment at the rheumatology service of a university hospital were included. Chest circumference, manual muscle testing, general well-being (Visual Analogue Scale - VAS), the Fatigue Severity Scale, the Rivermead Mobility Index, the Beck Anxiety Inventory, and the Nottingham Health Profile were used for evaluation. The average number of days hospitalized was 15.57 ±15.11. Mean disease duration was 7.91 ±9.34 years. Respiratory rate per minute was 22.55 ±6.03. Chest circumference measurement at rest was 97.01 ±9.70 cm, inspiration was 99.71 ±9.67 cm, expiration was 94.10 ±13.91 cm. Quadriceps muscle strength (on a scale of 0-5) was 4.26 ±0.74 on the right and 4.16 ±0.76 on the left; biceps brachii muscle strength was 4.46 ±0.64 on the right and 4.39 ±0.78 on the left. The VAS score was 6.03 ±2.51; the Rivermead Mobility Index was 11.41 ±4.11; the Nottingham Health Profile total score was 39.18 ±22.44; the energy level sub-score was 52.89 ±37.06. History of previous hospitalization was found in 42 patients (43.8%). Five patients (5.2%) were at bed level, 4 patients (4.2%) were at sitting level, 7 patients (7.3%) were at standing level, and 80 patients (83.3%) were at walking level. Seventeen patients (17.7%) used assistive devices for mobilization. Sixty-one patients (63.5%) were fatigued, and 21 patients (21.9%) had moderate anxiety. Inspiratory capacity of patients hospitalized in rheumatology service is low. Their respiratory rate is higher than the normal value. Their mobility and energy levels are at average values while fatigue and anxiety levels need to be considered. In addition to pharmacological treatments, we recommend that patients hospitalized in rheumatology service be supported by appropriate exercises provided by physiotherapists.

The influence of collar parameters on local scour mechanism around the circular pier at the bend

Analysis of bridge failures due to scouring has been extensively studied by different researchers in recent years and as a result various methods of controlling local scour cavity have been given. Since most of the research in this field has been done on straight paths and also the complexity of the flow pattern in bends, studying the scouring pattern around the bridge piers located in the bends has become a necessity. Therefore, one of the main objectives of this study is to investigate the scouring around the circular piers which are protected by collars at the river bends. The performance of the collar significantly depends on its level around the pier, which has been studied in this study. The results showed that the optimal performance of this structure, in positions 60°, 90° and 120° at the level of 0.2 pier width under the bed with 3 mm thickness (0.06 of pier width) by approximately 68, 63 and 70% of the maximum pier scour depth was reduced compared with collarless pier, respectively. By analyzing the results of this research, it was observed that the optimum level range of collar around the pier at various bend angles is the initial bed level up to 0.4 times the pier width at the bottom of the incipient level of the bed. Moreover, getting closer to the plate placement level toward the initial bed elevation enhances the collar’s function in decreasing scouring.

Agitation dredging of silt and fine sand with Water Injection Dredging, Tiamat and Underwater Plough: a case study in the Port of Rotterdam

Abstract Purpose Agitation dredging has gained popularity as an environmentally friendly and cost-effective method for port maintenance. One of the advantages of agitation dredging is the ability to transport sediments out of the port area using natural currents. The effect of the different agitation methods on sediment and water properties has rarely been investigated in a single pilot project. This research aims to study the effects of agitation methods in silt and sand-dominated areas that are frequently maintained. Methods The effects of water injection dredging, (WID) underwater ploughing (UWP) and Tiamat on sediment properties are investigated in the Port of Rotterdam. In-situ measurements and laboratory measurements are carried out to determine changes in the bed level, the particle size distribution of the bed, the turbidity in the water column and the dispersion distance of the sediment plume due to agitation dredging. Results The results of the in-situ monitoring of the agitation pilots allow a comparison of the changes in sediment and water properties before, during and after agitation dredging. The production, advantages and limitations of the tested agitation dredging methods are discussed. Conclusion The in-situ measurements show that WID, Tiamat and UWP can be successfully used for the agitation of sediments and their removal from the silt and sand-dominated areas. The production of the tested agitation methods is higher for silty than sandy sediments. In general, the selection of the agitation equipment can be made based on environmental regulations, sediment properties and hydrodynamic conditions.

Study of the Vibration Isolation Properties of a Pneumatic Suspension System for the Seat of a Working Machine with Adjustable Stiffness

This paper presents a study of the vibration isolation properties of pneumatic suspension systems for work machinery seats, with a particular focus on adjustable stiffness. It highlights the contribution that semi-active seat suspension systems make to vibration reduction, ultimately leading to improved passenger comfort levels and increased safety for vehicle users. The primary objectives of the research were twofold: firstly, to identify the key parameters of the apneumatic vibration isolation system; and secondly, to evaluate its performance in improving vibration damping. This entailed the development of a mathematical model that would foreground the movement through simulations based on different initial pressures, thus enabling the accurate prediction of real-life scenarios concerning the vibration-damping characteristics of the seating system, taking into account the different design options available for working machine technology applied at the test bed level, of which the pneumatic isolator is an integral component. In the cognitive process, the verification and validation of the formulated theoretical model play an important role. This approach enables the behaviour of the actual system to be inferred from the results of simulation studies, thus allowing the design of an appropriate vibration control system. By simulating different air bellow pressures, the characteristics of the seat suspension system can be assessed. This study provides valuable insights into optimising the vibration-damping capability of the air suspension system.

Discrete element analysis of the dynamic behavior of ballast track-subgrade system under train dynamic load

To study the dynamic response law of the ballast track-subgrade coupling system under the action of train dynamic load, considering the real shape of ballast particles, a refined discrete element model of the rail-sleeper-ballast bed-subgrade coupling system was established. The established model can realistically simulate the coupling mechanism between irregular ballast particles, between track panel and ballast bed, and between ballast bed and subgrade under train dynamic load. The validity of the established model is verified using on-site measurement results. This study, from a microscopic perspective, focuses on particle contact forces, vibrations, and frictional energy consumption in the rail-sleeper-ballast bed-subgrade coupling system under train dynamic load and investigates the influence of train speed and axle weight. Results show that an increase in train speed and axle weight enhances the number and probability distribution of strong force chains between ballast particles, increasing the risk of particle breakage and deterioration. The influence range and depth in the ballast bed-subgrade system increase with the train's speed and axle weight. Due to the granular nature of the ballast bed, the vibration acceleration distribution of ballast particles under train dynamic loads is relatively random. Overall, the vibration level of the ballast bed increases with train speed and axle weight. The frictional energy consumption of ballast particles rapidly grows as the train's bogie load passes, and the effect of train axle weight on the frictional energy consumption of ballast particles is more significant than the train's speed.

Evaluating the comprehensive flood impact assessment on the head reach of the Chiniot dam project

The major sources of surface water available to Pakistan are perennial flows of the River Indus and its tributaries i.e. Jhelum and Chenab Rivers. The creation of a reservoir of 0.9 MAF Capacity will cause the water level to rise and reduction in flow velocity on the Chenab River upstream of Chiniot Bridge. Consequently, it will cause sediment deposition which would further increase the water level due to the raised river bed level by deposited sediments. To study this storage, the reservoir has been modelled in HEC-RAS software to assess pre-dam and post-dam scenarios to simulate different conditions of river flow for water surface profile and sediment delta modelling of the reservoir reach, using historical daily water and sediment flows (1985–2022). The results of flood routing showed that the reservoir has attenuated the peak flood volume with safe releases at downstream side with proper operation of spillway gates. The average sediment inflow in the reservoir is worked out to be 38.4 metric tons. The results of sediment modelling and reservoir flood management indicated that after every 05 years of normal reservoir operation, reservoir flushing is recommended. Without sediment flushing, the river bed would be further raised beyond 189.0 m due to incoming sediment, resulting in further rise of water level up to 192.8 m which is the existing crest level of upstream training works of Talibwala Motorway Bridge.

Port Accessibility Depends on Cascading Interactions between Fleets, Policies, Infrastructure, and Hydrodynamics

Reducing waiting times is crucial for ports to be efficient and competitive. Important causes of waiting times are cascading interactions between realistic hydrodynamics, accessibility policies, vessel-priority rules, and detailed berth availability. The main challenges are determining the cause of waiting and finding rational solutions to reduce waiting time. In this study, we focus on the role of the design depth of a channel on the waiting times. We quantify the performance of channel depth for a representative fleet rather than the common approach of a single normative design vessel. The study relies on a mesoscale agent-based discrete-event model that can take processed Automatic Identification System and hydrodynamic data as its main input. The presented method’s validity is assessed by hindcasting one year of observed anchorage area laytimes for a liquid bulk terminal in the Port of Rotterdam. The hindcast demonstrates that the method predicts the causes of 73.4% of the non-excessive laytimes of vessels, thereby correctly modelling 60.7% of the vessels-of-call. Following a recent deepening of the access channel, cascading waiting times due to tidal restrictions were found to be limited. Nonetheless, the importance of our approach is demonstrated by testing alternative maintained bed level designs, revealing the method’s potential to support rational decision-making in coastal zones.

Scour at the rear side of rubble mound revetments due to random wave overtopping: Laboratory experiments

This study presents the physical model experiments on the wave overtopping induced bed level changes at an unprotected rear side of a rubble mound revetment with a crown wall. In the experiments, the wave conditions, the backfill material size, and the backfill depth (vertical distance from the crest level to the rear side bed level) are varied. Two mobility parameters, namely the densimetric overtopping discharge and the relative fall velocity, are introduced to represent the initiation of motion and suspension of the backfill material, respectively. The temporal evolution of scour depth at the rear side is related to the mobility parameter, the number of waves and the backfill depth utilizing regression analyses. The effect of the backfill depth on the scour is found very limited for the available data set. However, the time scale of the scour is found to be related with the backfill depth only. For the present data set, it varied within a range of 1500–16000 number of waves approximately, with an average of 5600 waves. An equilibrium scour profile is reached 3 to 4 times the time scale. The geometry of the scour profile is expressed in terms of the scour depth, based on the equilibrium scour profile data.

Experimental study and numerical simulation of the impact of under-sleeper pads on the dynamic and static mechanical behavior of heavy-haul railway ballast track

AbstractLaying the under-sleeper pad (USP) is one of the effective measures commonly used to delay ballast degradation and reduce maintenance workload. To explore the impact of application of the USP on the dynamic and static mechanical behavior of the ballast track in the heavy-haul railway system, numerical simulation models of the ballast bed with USP and without USP are presented in this paper by using the discrete element method (DEM)—multi-flexible body dynamic (MFBD) coupling analysis method. The ballast bed support stiffness test and dynamic displacement tests were carried out on the actual operation of a heavy-haul railway line to verify the validity of the models. The results show that using the USP results in a 43.01% reduction in the ballast bed support stiffness and achieves a more uniform distribution of track loads on the sleepers. It effectively reduces the load borne by the sleeper directly under the wheel load, with a 7.89% reduction in the pressure on the sleeper. Furthermore, the laying of the USP changes the lateral resistance sharing ratio of the ballast bed, significantly reducing the stress level of the ballast bed under train loads, with an average stress reduction of 42.19 kPa. It also reduces the plastic displacement of ballast particles and lowers the peak value of rotational angular velocity by about 50% to 70%, which is conducive to slowing down ballast bed settlement deformation and reducing maintenance costs. In summary, laying the USP has a potential value in enhancing the stability and extending the lifespan of the ballast bed in heavy-haul railway systems.

Semicircular Coastal Defence Structures: Impact of Gap Spacing on Shoreline Dynamics during Storm Events

Coastal erosion poses significant challenges to shoreline management, exacerbated by rising sea levels and changing climate patterns. This study investigates the influence of gap spacing between semicircular coastal defence structures on shoreline dynamics during storm events. The innovative design of these structures aims to induce a drift reversal of prevalent sediment transport while avoiding interruption of alongshore sediment drift, thus protecting the beach. Three different gap spacings, ranging from 152 m to 304 m, were analysed using the XBeach numerical model, focusing on storm morphodynamic behaviour. Methodologically, hydrodynamic and morphodynamic analyses were conducted to understand variations in significant wave heights adjacent to the structures, in accretion and erosion volumes, and changes in bed level under storm conditions. The study aims to elucidate the complex interaction between engineered coastal protection solutions and natural coastal processes, providing practical insights for coastal management practices. Results indicate that installing semicircular coastal defence structures influences sediment dynamics during storm events, effectively protecting stretches of the coast at risk. Optimal gap spacing between structures is crucial to mitigating coastal erosion and enhancing sediment accumulation, offering a sustainable shoreline protection approach. The findings underscore the importance of balanced location selection to optimize protection benefits while minimizing adverse morphological effects. Overall, this research contributes to advancing knowledge of hydro-morphological phenomena essential for effective coastal engineering and informs the design and implementation of more sustainable coastal protection strategies in the face of increasing coastal erosion and sea level rise challenges.

Experimental investigation of temporal evaluations of scouring downstream of culvert

The investigation of bed topography downstream of culverts is very important. Since bed topography goes through extreme changes through time, this study investigated the temporal evaluations of bed topography. Also, the bed level downstream of culverts, as one of effective parameters in topography in different time spans, was investigated. One of the most important findings of the study is that with increasing the experiment time and approaching the equilibrium moment, the change percentage of the maximum scour depth decreased. Also with changes to and decrease in the bed level downstream of the culvert, the change percentage of the depth scour decreased. Another salient finding of this study was that the maximum scour over the beginning durations of the tests in case of equal downstream level and culvert bed level was approximately equal to the maximum scour in cases where the downstream bed level differed from the culvert bed level by 0.067 and 0.13 times the culvert mouth width.

Microvascular dysfunction associated with reduced nailfold capillary density in patients with ischemia with no obstructive coronary artery disease

Abstract Funding Acknowledgements None. Introduction The impairment of microvascular function present in coronary microcirculation with chronic angina without obstructive coronary arteries. There are insufficient data in the literature regarding possible generalized microangiopathy in this population. Aim The aim of this study is to demonstrate whether patients with Angina with No Obstructive Coronary Artery Disease (ANOCA) compared to individuals without coronary microvascular dysfunction (CMD) are characterized by a different level of nailfold capillaroscopy abnormalities. Methods We examined 18 participants without CMD - non-CMD group [9 female, 50%, mean age: 54.4±8.1 years) and 26 patients with ANOCA - CMD group (22 female, 84,6%, mean age : 53.2±10.7 years). Functional coronary angiography was performed for the assessment of coronary microcirculation in all patients. Coronary flow reserve (CFR) and index of microvascular resistance (IMR) were measured in the left anterior descending coronary artery using a temperature/pressure sensor-tipped guidewire. In addition, the assessment of skin microcirculation was performed by capillaroscopy, a non-invasive technique to evaluate small vessels of the microcirculation in the nailfold, using stereomicroscope in all patients. Results In CMD group, mean CFR and IMR were 1.34±0.6 and 44.8±28, respectively. Out of the 26 MVD patients with abnormal CFR, 7 of them (27%) had a normal value of IMR, indicating functional microvascular dysfunction. On the other hand, 18 patients (69%) had an abnormal IMR, indicating structural microvascular dysfunction. Capillary density in patients with MVD was significantly decreased compared to the control group (7.6±2.2 vs 10.9±1.8 vessels/mm, p=0.04). The difference in capillary density between the two groups was statistically significant after adjustment for multiple comparisons (p<0.05). No significant difference was found in body mass index, renal function, medical history of dyslipidemia, diabetes mellitus and smoking status between the two groups (p<0.05). Conclusion Nailfold capillary density was reduced in ANOCA patients compared to control group. These data may provide new insights regarding possible generalized microangiopathy in CMD patients. These results suggest that there is an association between microcirculatory impairment at both heart and peripheral vascular bed level.

Observation Of Ocean Wave Based On Binocular Vision In The Swash Zone Of Yazhou Bay

Due to climate change, extreme weather events frequently occur. This can increase the probability of typhoon, resulting in storm surge more frequently. Meanwhile, the severe movement of ocean wave is generated. Ocean wave on the coastal zone can results in retreat of the coastlines and erosion for the beach. The research on the ocean wave in storm surge process based on field observation is not only able to provide the basic data for the validation of numerical model of storm surges but also significant to prevent the loss of beaches resources in the extreme climate condition. The previous studies of swash zone using video technology concentrated on experimental scale (De Vries et al., 2011), and the research parameters mostly focused on bed and water level (Wanek et al., 2006), while there is a lack of the research of ocean wave parameters. The binocular vision observation system, which mainly consists of two cameras, has been a powerful technical support in acquiring 3D information of ocean wave. Compared with the measurement of manual, radar (Harry et al., 2018) and satellite remote, the binocular vision method is not only hardly affected by weather condition, but also can acquire the continuous image data. In addition, two cameras with high resolution can obtain high precision measurement results. This study aims at obtaining the wave height of the swash zone in storm surge process.