P-wave Research Articles

In-line valve condition assessment by transient analysis

Negligently partially closed in-line valves in pipes cause undesirable minor head losses that reduce the carrying capacity and increase operating costs attributable to energy consumption. However, few obtained results of in-line valves condition assessment has been offered in the literature. The paper makes further investigations on the interaction between the valve and the transient pressure wave, which provides experimental data support and reference opinions for the transient wave detection of in-line valve status with practical applications. The position of the in-line valve is evaluated by a simple equation and the propagation of transient pressure wave was analyzed. The relevant equations are derived and correlation analysis was performed. Based on the pressure increase value, the head loss coefficient or valve opening degree can be determined, and feasible suggestions for detecting the valve opening degree using transient waves have been made. Under the selected experimental conditions, the absolute error between the calculated valve opening degree and the actual opening degree is below 0.06 (1 for fully open valve opening and 0 for fully closed valve opening), proving that the valve opening assessment method is effective. This paper demonstrates the application of transient wave technology in real-time monitoring and assessment of valve positions. Through this technology, the valve positions in water distribution systems can be optimized effectively, thereby reducing resistance losses, meeting varying water demands, avoiding unnecessary energy waste, and enhancing the overall energy efficiency of the water supply system.

Vascular function and skeletal fragility: a study of tonometry, brachial hemodynamics, and bone microarchitecture.

Osteoporosis and cardiovascular disease frequently occur together in older adults; however, a causal relationship between these 2 common conditions has not been established. By the time clinical cardiovascular disease develops, it is often too late to test whether vascular dysfunction developed before or after the onset of osteoporosis. Therefore, we assessed the association of vascular function, measured by tonometry and brachial hemodynamic testing, with bone density, microarchitecture, and strength, measured by HR-pQCT, in 1391 individuals in the Framingham Heart Study. We hypothesized that decreased vascular function (pulse wave velocity, primary pressure wave, brachial pulse pressure, baseline flow amplitude, and brachial flow velocity) contributes to deficits in bone density, microarchitecture and strength, particularly in cortical bone, which is less protected from excessive blood flow pulsatility than the trabecular compartment. We found that individuals with increased carotid-femoral pulse wave velocity had lower cortical volumetric bone mineral density (tibia: -0.21 [-0.26, -0.15] standardized beta [95% CI], radius: -0.20 [-0.26, -0.15]), lower cortical thickness (tibia: -0.09 [-0.15, -0.04], radius: -0.07 [-0.12, -0.01]) and increased cortical porosity (tibia: 0.20 [0.15, 0.25], radius: 0.21 [0.15, 0.27]). However, these associations did not persist after adjustment for age, sex, height, and weight. These results suggest that vascular dysfunction with aging may not be an etiologic mechanism that contributes to the co-occurrence of osteoporosis and cardiovascular disease in older adults. Further study employing longitudinal measures of HR-pQCT parameters is needed to fully elucidate the link between vascular function and bone health.

Age and Sex Differences in the Contribution of Mean Arterial Pressure to Pulse Pressure Before Middle Age.

A lower ability to buffer pulse pressure (PP) in the face of increasing mean arterial pressure (MAP) may underlie the disproportionate increase in systolic blood pressure (SBP) in women from young adulthood through middle-aged relative to men. To evaluate the contribution of MAP to the change in PP and pressure wave contour in men and women from young adulthood to middle age. Central pressure waveform was obtained from radial artery applanation tonometry in 312 hypertensive patients between 16 to 49 years (134 women, mean age 35 ± 9 years), 185 of whom were on antihypertensive treatment. Higher MAP levels (≥ 100 mmHg) were significantly associated with higher brachial and central SBP (P < 0.001), PP (P < 0.001), incident wave (P = 0.005), AP (P < 0.001), and PWV (P < 0.001) compared to lower MAP levels. The relationship between MAP and brachial PP (P < 0.001), central PP (P < 0.001), incident wave (P < 0.001), and AP (P < 0.01), but not PWV, strengthens with age. The age-related increase in the contribution of MAP to brachial PP (P < 0.001), central PP (P < 0.001), and incident wave (P < 0.001) was more prominent in women than in men beginning in the fourth decade. In multiple regression analyses, MAP remained a significantly stronger predictor of central PP and incident wave in women than in men, independent of age, heart rate, and antihypertensive treatment. In turn, age remained a significantly stronger predictor of central PP and incident wave in women than in men, independent of MAP, heart rate, and antihypertensive treatment. Women of reproductive age showed a steeper increase in PP with increasing MAP, despite comparable increases in arterial stiffness in both sexes. The difference was driven by a greater contribution of MAP to the forward component of the pressure wave in women.

Stability Of Estuarine Groyne During Overflowing Long-Period Primary Ship-Induced Waves Based On Laboratory Experiments

For the last two decades, significant damage to groyne structures has been observed in the German Elbe estuary. The main reason is the generation of primary ship-induced wave loading. The stern wave of the primary wave system appears as an overflowing over groyne, leading to damage at the crest and lee side of the structure due to the presence of high overflowing flow velocities (Melling et al., 2020). Therefore, overflowing flow velocities and damage were quantified by means of two different experimental setups; the flow experiments and the damage experiment. The flow experiment involved testing scaled physical models under continuous free-flow conditions. A Particle Image Velocimetry (PIV) setup was used to capture flow velocities at the crest and lee side slope. A dimensionless flow velocity equation is obtained for overflowing flow over groyne structures. The damage experiment assessed the impact of overflowing waves at the crest and lee side on one of the scaled physical models. Measurements were conducted via Structure from Motion principles (SfM) and the damage is expressed in damage parameters S for varying wave heights and freeboard levels. This parameter describes the damage by width-averaged eroded area made dimensionless by the squared nominal stone diameter. Furthermore, the assessment considered the determination of the damage limits (initiation, intermediate, and failure) of a groyne structure for these waves. The results revealed the relation between the wave height and the freeboard and damage. Furthermore, by regarding the flow velocity explicitly a more fundamental understanding, and more generally applicable design approach might be obtained. The insights gained from this research contribute to an enhanced understanding of groyne behaviour under overflowing long- period ship-induced waves. By highlighting the significance of the flow velocities for waves and freeboard levels, this study provides valuable information for optimizing the design and maintenance of estuarine groynes that are prone to these types of wave-induced loads.

Extension of interval between adjacent pulse delivery cycles to deal with myocardial ischemia by intravascular lithotripsy: case report

BackgroundIntravascular lithotripsy (IVL) represents a novel approach in the management of coronary calcification. This technique employs acoustic pressure waves, generated by a shockwave balloon, to effectively fracture both superficial and deep calcification in situ. The efficacy and safety of IVL have been convincingly demonstrated through the Disrupt CAD I-IV studies. While IVL is associated with the occurrence of atrial and ventricular arrhythmias, there is no evidence to indicate it causes myocardial ischemia.Case DescriptionA 71-year-old man was admitted presenting with chest pain. His previous coronary angiography revealed stenosis and calcification in the left anterior descending branch. An attempt to predilate the lesion using two Lacrosse non-slip element balloons was unsuccessful. Ventricular premature beats and transient ST-segment depression were captured during the utilization of IVL. The operator gradually extended the pulse emission interval across two consecutive cycles to mitigate myocardial ischemia. Notably, when the interval reached 30s, the patient had no chest pain or ST-segment changes. Subsequent images of intravascular ultrasound confirmed calcification ruptures. Therapeutic intervention included the placement of a stent and the application of a drug-coated balloon in the left anterior descending branch. A telephonic follow-up six months later indicated the patient had no discomfort.ConclusionsThis case underscores the effectiveness of gradually extending the pulse emission interval as a strategic complement to the clinical application of IVL. In certain clinical scenarios, it may become imperative to suspend the pulse delivery to improve myocardial blood supply.

Modeling hyperthermia-based prostate cancer treatment in the presence of core-shell nanoparticles and large blood vessels under different ultrasound sonication patterns

The use of nanoparticles, as enhancing agents to transform ultrasound energy into heat for tumor destruction, is a promising approach to improve the efficacy of thermal-based cancer therapies. This study aimed to evaluate the effectiveness of core-shell type nanoparticles and the heat loss due to blood flow in large vessels under different patterns of ultrasound sonication in the hyperthermia-based treatment of the prostate cancer. For this purpose, the ultrasound attenuation coefficient in the prostate tumor embedded with nanoparticles was calculated using a scattering theory that was developed for core-shell type particles. Using the attenuation coefficient and the linear pressure wave equation, the acoustic power dissipated per unit volume of a three-dimensional (3D) model of the prostate tumor and its surrounding tissues was calculated. By simultaneous solving the bioheat, the convective energy, the continuity, the Navier-Stokes, and the thermal dose equations, the temperature and thermal dose distribution were computed in the model. The attenuation coefficient of the tumor showed a decreasing trend with increasing the thickness of the silica shell coating the magnetite or titania core. The capability of nanoparticles to enhance heat production in the medium was directly, and the blood flow heat loss was inversely, related to the degree of focus of the ultrasound beam. The thermal response of the tumor was influenced by its size and geometry, as well as the acoustic intensity. Titania nanoparticles were more efficient than the magnetite nanoparticles in ultrasound attenuation and heat production in the medium. Our findings can be useful in understanding the factors affecting the hyperthermia-based treatment of the prostate cancer using a combination of ultrasound and nanoparticles.

Ultrahigh energy efficiency from a supersonic underwater ultrasound source

The present work is dedicated to an experimental and theoretical study of an innovative underwater ultrasound source. The source works using a technique in which a pulsed power generator using the impedance mismatch of a long high-voltage coaxial cable generates a train of voltage impulses with a very high pulse repetition frequency of the order of a few MHz. Applying this train of voltage impulses to a pair of underwater electrodes generates a streamer-initiated breakdown of water and, subsequently, a plasma column connecting the electrodes over a very large inter-electrode gap of 55 mm. The interaction of the long plasma column thus formed with the surrounding water produces a rapidly expanding vapor bubble, an “instrument” producing a strong pressure wave with an overall energy efficiency of 24%, an order of magnitude higher than most underwater pressure sources reported in the literature.

A finite volume model for maintaining stationarity and reducing spurious oscillations in simulations of sewer system filling and emptying

This paper introduces a model for simulating the unsteady dynamics of sewer systems filling and emptying, offering greater accuracy and stability. This article presents two novel contributions: first, the HLLS scheme (Harten–Lax–van Leer + Source term) is adapted to ensure the preservation of stationary conditions not only in free surface flows, as originally conceived, but also in pressurized flows and mixed flow scenarios. Second, a new method is proposed for the treatment of open channel flow cells near pressurization or adjacent to pressurized cells to minimize spurious oscillations when utilizing the two-component pressure approach (TPA) model. To verify the new model's effectiveness, it was tested for various conditions against the outcomes of the Open Source Field Operation and Manipulation (OpenFOAM) computational fluid dynamics (CFD) model. Furthermore, to demonstrate the model's potential for simulating real systems, the model was applied to three sewer systems that closely resemble real-world conditions, each of which had been intentionally modified for confidentiality purposes. The results show that the improved model successfully maintains stationary conditions within a sloped pipe across various flow conditions, while also preventing spurious oscillations at mixed flow interfaces even when using a pressure wave speed of 1000 m s − 1 .

Wave Pressures Acting On The Pavement Behind The Sloping Revetment

A physical experiment was performed to seek an empirical equation predicting the wave force acting on the upper surface of the pavement behind the revetment parapet due to wave overtopping as well as the uplift force acting on the underlayer of the pavement induced by the wave pressure passing through the core layers of the revetment. The experiment was carried out by installing pressure transducers along the upside and downside of the pavement with different configuration of the parapet, water depth, relative freeboard, and armor layer thickness. Then, the wave pressure and force on the pavement was analyzed under various incoming wave conditions. Based on the analysis results, major parameters affecting the wave forces were identified and an empirical equation for evaluating the forces on the pavement is suggested.

Assessing pressure wave components for aortic stiffness monitoring through spectral regression learning.

The ageing process notably induces structural changes in the arterial system, primarily manifesting as increased aortic stiffness, a precursor to cardiovascular events. While wave separation analysis is a robust tool for decomposing the components of blood pressure waveform, its relationship with cardiovascular events, such as aortic stiffening, is incompletely understood. Furthermore, its applicability has been limited due to the need for concurrent measurements of pressure and flow. Our aim in this study addresses this gap by introducing a spectral regression learning method for pressure-only wave separation analysis. Leveraging data from the Framingham Heart Study (2640 individuals, 55% women), we evaluate the accuracy of pressure-only estimates, their interchangeability with a reference method based on ultrasound-derived flow waves, and their association with carotid-femoral pulse wave velocity (PWV). Method-derived estimates are strongly correlated with the reference ones for forward wave amplitude ( ), backward wave amplitude ( ), and reflection index ( ) and moderately correlated with a time delay between forward and backward waves ( ). The proposed pressure-only method shows interchangeability with the reference method through covariate analysis. Adjusting for age, sex, body size, mean blood pressure, and heart rate, the results suggest that both pressure-only and pressure-flow evaluations of wave separation parameters yield similar model performances for predicting carotid-femoral PWV, with forward wave amplitude being the only significant factor (P < 0.001; 95% confidence interval, 0.056-0.097). We propose an interchangeable pressure-only wave separation analysis method and demonstrate its clinical applicability in capturing aortic stiffening. The proposed method provides a valuable non-invasive tool for assessing cardiovascular health.

Wave Pressure on the Lateral Surface of Piles Depending on the Relative Open Area of the Piled Breakwater

Wave Pressure on the Lateral Surface of Piles Depending on the Relative Open Area of the Piled Breakwater

Frequency shift of parametric sound by face-to-face pair of sources in relative motion.

This paper reports an acoustic phenomenon regarding a parametric sound source (also referred to as a parametric array): a secondary sound wave is generated from the nonlinear interaction of multiple primary sound waves with varied frequency components, particularly when two relatively moving sound sources face each other. It was found that the frequency of the secondary wave fluctuated according to the source movement and provided a theoretical explanation for this phenomenon. It is experimentally demonstrated that this frequency shift was approximately proportional to the velocity of the moving source toward the fixed source and to the driving frequency of the moving source. This phenomenon has much in common with the Doppler's effect, but its unique property is that the frequency shift depends on neither the observation position nor the source velocity toward the observer. These sound generation principles enable measurement of the velocity of slowly moving sound sources while maintaining a low-modulation frequency band and a short measurement time. This phenomenon can potentially be applied to an alternative approach for acoustic noncontact velocimetry of moving objects.

Interstage transmission and differential analysis of pressure fluctuations in multistage centrifugal pump-as-turbine

Pumps as turbines (PATs) are used in petroleum and chemical industries to recover high-pressure residual energy. Multistage PATs allow for a wider energy recovery interval and wider range of applications. However, because multistage centrifugal pumps were not originally designed for turbine conditions, complex pressure fluctuations occur, impacting the stable operation and performance of multistage PAT. Pressure fluctuation is essentially a wave, and by analogy with the wave intensity definition, pressure fluctuations were quantified using the pressure wave energy flow density, and the pressure fluctuation patterns at different stages were investigated. The findings reveal significant differences in the intensity of pressure fluctuations at different locations within the multistage PAT. Specifically, the pressure fluctuation intensity is significantly higher from the second to the final stage, compared to the first stage. The difference in inlet flow conditions is the main reason for this difference in pressure fluctuations between stages. The inlet inflow from the second to the final stage is subject to rotational effects that exacerbate the difference in pressure fluctuation intensity between stages. Pressure fluctuations are found to be negatively related to the distance from the source of fluctuations and positively related to the flow state. Different flow conditions and interaction regions of the impeller affect the distribution of pressure fluctuation intensity and the distribution of pressure fluctuation energy across different frequency domains within the guide vanes. The main source of fluctuations in the shaft frequency and four times the shaft frequency is the impeller inlet interaction region, whereas the fluctuations in the blade passing frequency originate from the impeller outlet interaction region. This paper provides a reference for improving the stable operation of multistage PATs.

Central and peripheral cardiovascular responses after acute dietary nitrate supplementation in post-menopausal women

The transition to menopause is accompanied by augmented cardiovascular disease risk, partially attributed to reduced nitric oxide (NO) bioavailability. Despite a lower arterial stiffness than men, postmenopausal women are susceptible to increased aortic pulsatile hemodynamic load because of greater pressure wave reflection and vascular dysfunction. Increasing bioavailable NO with dietary nitrate has shown promise to reduce aortic (aSBP) and brachial (bSBP) systolic pressure healthy postmenopausal women. However, there are limited reports comparing hypertensive (HTN) and normotensive (NTN) postmenopausal women regarding wave separation analysis and vascular function following dietary nitrate supplementation. This study investigated if acute dietary nitrate supplementation would improve aortic hemodynamics, wave reflection characteristics, vascular stiffness, and vasodilatory function. We hypothesized that dietary nitrate would lower pulse wave velocity in hypertensives, lower aortic and brachial blood pressures and forward and backward wave magnitude and increase microvascular, but not macrovascular function in both groups. Fourteen postmenopausal women (n=7 HTN; n=7 NTN) participated in a two-day randomized crossover study design with dietary nitrate (nitrate rich, NR) or a placebo control (NP). Central and peripheral hemodynamics and carotid-femoral pulse wave velocity (cfPWV) were performed with a SphygmoCOR Excel, simultaneous resting macro- and- microvascular function was assessed using flow-mediated vasodilation (FMD) and post occlusive reactive hyperemia (PORH) using near-infrared spectroscopy. aSBP was reduced significantly following NR supplement within groups (HTN: NP 126±2 NR 120±1mmHg) and NTN group (NP 110± 1 NR 104±3mmHg p&lt;0.05). Forward pulse height HTN (NP 29±1.4 NR 26.3±1.4mmHg) NTN (NP 25.6±0.9 NR 24±2.7mmHg) and reflected pulse height HTN (NP 18.2±0.08 NR 17.2±0.4mmHg) NTN (NP 17.7±0.2 NR 15.7±1.07mmHg) were not different. cfPWV was faster in the HTN group and slowed with a NR supplement (HTN: NP 8.2±0.29 NR 7.4±0.31m/s; NTN NP 7.1±0.23 NR 6.6±0.62m/s p&lt;0.05). A significant interaction for %FMD was found (HTN: NP 7.3±0.8 NR 6.2±0.8%; NTN NP 6.6±0.7 NR 9.4±0.7%). Further, we found no difference in the NIRS derived microvascular function measurements (HTN: NP 1.9±0.2 NR 1.7±0.3%/s; NTN NP 1.6±0.1 NR 1.4±0.2%/s p&gt;0.05). These data indicate that dietary nitrate consumption led to a substantial reduction in aortic hemodynamics and reduced pulse wave velocity regardless of hypertension status. Interestingly, macrovascular, but not microvascular vasodilatory function was improved in the NTN women only. Dietary nitrate supplementation appears to have differential effects when considering HTN and NTN postmenopausal women. Supported with funds from The University of Wisconsin-La Crosse RSEL graduate grant. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Numerical study of the behavior of a near-wall bubble under the influence of an acoustic wave

Acoustic cavitation has been applied to many ultrasonic fields, but its characteristics are not fully understood, especially near the wall. To analyze the dynamics of a near-wall acoustic bubble, an acoustic pressure wave boundary condition is developed in the OpenFOAM platform. We first conducted the model’s validation with an experiment to prove its accuracy. The bubble’s radius increases when the bubble is excited by the lower-pressure wave, and it decreases under the higher-pressure wave. When the bubble collapses, its pressure and temperature will reach the maximum value. In accordance with the non-dimensional distance, the dynamics of the acoustic-driven bubble are classified into three types, i.e., the liquid jet not touching the nearby wall, the liquid jet touching the wall, and no obvious liquid jet. The maximum value of pressure and temperature increases with the dimensionless distance decreasing if the dimensionless distance is small. However, there is no variation of these peak values with dimensionless distance if the dimensionless distance is large.

The simulation and experiments of a high frequency single stage pulse tube cryocooler with two cooled thermal sinks

In the application of infrared detectors, pulse tube cryocoolers are required to provide cooling power at different temperature ranges simultaneously with light weight and compact construction. In this paper, a single stage pulse tube cryocooler was designed to provide cooling power at different temperature ranges with an extra cooled thermal sink placed in the middle of the regenerator. The axial distribution of volume flow and pressure wave of cryocooler with middle heat exchanger and without middle heat exchanger were compared theoretically. To verify the simulation results, a series of experiments were carried out. As a result, the cooling power of cryocoolers with middle heat exchanger was decreased at 80 K, and 0.5 W @ 88.5 K & 0.5 W @ 195.8 K of cooling power was obtained simultaneously at 45 W input power.

No sex differences in the cardiac responses during high altitude sojourn to 4300 m

Ascent to high altitude reduces oxygen availability and provokes compensatory cardiovascular responses. Females may exhibit attenuated hypoxic ventilatory responses compared to males, which could subsequently exaggerate the cardiovascular response to high altitude among females. The purpose of this study was to examine sex differences in cardiac responses during high altitude sojourn in young, healthy males and females. We hypothesized that females would exhibit a greater reduction in arterial oxygen saturation, and greater cardiac dysfunction compared to males. 17 healthy adults (8 males, 24±4 yrs, BMI 25.7±3.1 kg/m2; 9 females, 23±4 yrs, BMI 24.5±3.0 kg/m2) underwent cardiac assessment via echocardiography at 1400 m and after an 8-day ascent to 4300 m. Left ventricular (LV) systolic function was assessed via ejection fraction and fractional shortening. Diastolic function was assessed as the ratio between early and late mitral filling velocities (E:A ratio). The subendocardial viability ratio (SEVR) was derived from carotid tonometry, and carotid pressure waves were integrated with echocardiography derived measures of left ventricular ejection to estimate a left ventricular pressure-volume loop and calculate stroke work. Ascent from 1400 m to 4300 m resulted in reduced end-tidal CO2 (-Δ8±3 [males], -Δ8±2 mmHg [females], p&lt;0.001), oxygen saturation (-Δ11±3 [males], -Δ11±5 % [females], p&lt;0.001), and LV fractional shortening (-Δ7.9±7.5% [males] -Δ1.0±6.4 % [females], p=0.028) in both groups. Despite greater stroke work among males (p=0.002), high altitude-induced changes were not statistically different compared to females (+Δ35±184 [males], +Δ3±113 mL/mmHg [females]). Changes in LV ejection fraction (-Δ1.9±14.4 [males], -Δ1.5±18.7 % [females]) mitral E:A (-Δ0.33±0.53 [males], -Δ0.09±0.64 au [females]), and SEVR (-Δ0.06±0.33 [males], +Δ0.15±0.20 au [females]) from 1400 to 4300 m were not statistically different between sexes. Ascent from 1400 to 4300 m decreased end-tidal CO2, arterial oxygen saturation, and select metrics of LV systolic function (e.g., fractional shortening), but LV diastolic function, stroke work, and SEVR was preserved in both males and females. We observed no apparent sex differences in the effects of 8-day sojourn to 4300 m on arterial oxygen saturation, or cardiac systolic and diastolic function. Additional research is necessary to confirm these results in the context of longer-term altitude exposure and acclimatization, and in older populations (middle-aged and older adults). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Evaluating wave force and interface fluid velocity distribution at the vicinity of a breakwater by considering consolidation of porous media

Previous studies have successfully simulated the interaction between wave and porous media using volume-averaged Reynolds-averaged Navier-Stokes (VARANS) equations. However, the consolidation of porous media subject to wave loading affects the progressing wave, which is crucial to computation of wave force and wave-porous media interface fluid velocity. Research on this aspect is scarce. This study adopted the u -p approximation for Biot dynamic consolidation theory to quantify the consolidation of porous media. The continuity condition on the interfaces between the wave and porous seabed was considered to achieve their interaction. Coupling algorithms of wave and porous seabed were validated against experimental measurements in the literature. An engineering case of wave traveling over a breakwater was examined, and computation results of wave pressures and interface fluid velocities at the vicinity of a breakwater by VARANS equations and wave-porous seabed coupling algorithm of this study were compared to explore the influence of the consolidation effect on the progressing wave.

Armor Damage On Groins Under Ship Wave Attack Using Field Data

The severity of damages to riverine structures, such as groynes or revetments, across German estuaries has increased in the past years due to the increase in the ship-induced loads. However, few studies can be found in the literature focused on the damage of rock slopes under ship wave attack. In this study, the field data of a rock-armored groyne (lateral slope 1/4 and rocks with nominal diameter Dn50»12.6cm and high density ρs=3.7t/m3) tracked for a year by Melling et al. (2020) is analyzed; the field campaign began after the structure was rebuilt and finished when the structure already presented severe damage. During this field campaign, the incident ship-induced primary waves and water levels were recorded, and laser scans of the groyne armor were taken. Using those field laser scans, damage curves along the life of the structure were derived. Also, ship data from the AIS was retrieved. Then, each increment of the damage (increment of the dimensionless eroded area, ΔSe) was related to a ship-wave event and a passing ship. The most significant variable to describe ΔSe was found to be the primary wave height Hp, while the best explanatory variables for Hp were the partial blockage factor, the ship length and width and the relative velocity of the ship. The shape of the dependence between these variables is also analyzed by pairs using copula space. A clear tail dependence is observed between several pairs. For instance, the pair ΔSe and Hp presents upper tail dependence, meaning that the high values of ΔSe and Hp are more correlated than the smaller ones. This implies that models more complex than Gaussian copula, which is commonly used in Coastal Engineering applications, might be needed to model the probabilistic dependence between the variables.

Quenching of Disk-Shaped Components in Aqueous Polymer Solutions

Abstract In addition to various advantages over oil quenching, quenching in aqueous polymer solutions can also have disadvantages. Under certain conditions, “explosive” phenomena can occur when quenching steel components in such solutions, leading to pressure waves and vibrations in the quenching tank, which can even destroy the weld seams of the tank in the long term. After these processes were analyzed in the past when quenching cylindrical shafts, the processes occurring with horizontally charged disks have now been investigated. The main difference between these two geometries lies in the size of the lower disk end face, which significantly impedes the outflow of evaporated portions of the aqueous polymer solutions and thus has a pronounced influence on the cooling behavior of disk-shaped components. The investigations to be presented here were carried out in a laboratory quenching tank. The type and concentration of the polymer, the flow type and the diameter of the inner bore of the disks were varied. Temperature and conductivity were measured and audio and video recordings were made to characterize the resulting cooling processes. Selected quenching variants are presented in detail in the article. Furthermore, key figures for characterizing the various cooling variants are compared and discussed.