Wave Measurements Research Articles

The effect of exercise on vascular health in chronic kidney disease: a systematic review and meta-analysis of randomized controlled trials.

Patients with chronic kidney disease (CKD) are at increased risk of cardiovascular disease. This increased risk cannot be fully explained by traditional risk factors such as hypertension. Endothelial dysfunction and arterial stiffness have been suggested as factors that explain some of the increased risk and are independently associated with important cardiovascular outcomes in patients with CKD. Studies in other disease populations have shown the positive effects of exercise on vascular dysfunction. The aim of this review was to determine whether exercise training interventions improve measures of vascular function and morphology in patients across the spectrum of CKD and which exercise training interventions are most efficacious. A systematic search of Medline, Embase, and the Cochrane Central Register identified 25 randomized controlled trials. Only randomized control trials using an exercise intervention with a nonexercising control group and at least one measure of vascular function or morphology were included. Participants were patients with nondialysis CKD or transplant patients or those requiring dialysis therapy. A systematic review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A meta-analysis was completed for pulse wave velocity, augmentation index, and measures of endothelium-dependent vasodilation. Data from 25 studies with 872 participants showed that exercise training reduced pulse wave velocity and augmentation index but had no effect on endothelium-dependent vasodilation. Subgroup analyses suggested that exercise interventions of at least moderate intensity were more likely to be effective. Limitations included the absence of observational studies or other interventions aimed at increasing habitual physical activity. Further studies are warranted to investigate which are the most effective exercise interventions.NEW & NOTEWORTHY A thorough systematic review and meta-analysis of the effects of exercise training on measures of vascular function in patients with chronic kidney disease, including arterial stiffness and endothelial function, were conducted. Subgroup analyses investigated how differences in exercise training, according to frequency, intensity, type, and timing, have an impact on the efficacy of the intervention.

MR Neurography and Quantitative Muscle MRI of Parsonage Turner Syndrome Involving the Long Thoracic Nerve.

Parsonage-Turner syndrome (PTS) is characterized by severe, acute upper extremity pain and subsequent paresis and most commonly involves the long thoracic nerve (LTN). While MR neurography (MRN) can detect LTN hourglass-like constrictions (HGCs), quantitative muscle MRI (qMRI) can quantify serratus anterior muscle (SAM) neurogenic changes. 1) To characterize qMRI findings in LTN-involved PTS. 2) To investigate associations between qMRI and clinical assessments of HGCs/electromyography (EMG). Prospective. 30 PTS subjects (25 M/5 F, mean/range age = 39/15-67 years) with LTN involvement who underwent bilateral chest wall qMRI and unilateral brachial plexus MRN. 3.0 Tesla/multiecho spin-echo T2-mapping, diffusion-weighted echo-planar-imaging, multiecho gradient echo. qMRI was performed to obtain T2, muscle diameter fat fraction (FF), and cross-sectional area of the SAM. Clinical reports of MRN and EMG were obtained; from MRN, the number of HGCs; from EMG, SAM measurements of motor unit recruitment levels, fibrillations, and positive sharp waves. qMRI/MRN were performed within 90 days of EMG. EMG was performed on average 185 days from symptom onset (all ≥2 weeks from symptom onset) and 5 days preceding MRI. Paired t-tests were used to compare qMRI measures in the affected SAM versus the contralateral, unaffected side (P < 0.05 deemed statistically significant). Kendall's tau was used to determine associations between qMRI against HGCs and EMG. Relative to the unaffected SAM, the affected SAM had increased T2 (50.42 ± 6.62 vs. 39.09 ± 4.23 msec) and FF (8.45 ± 9.69 vs. 4.03% ± 1.97%), and decreased muscle diameter (74.26 ± 21.54 vs. 88.73 ± 17.61 μm) and cross-sectional area (9.21 ± 3.75 vs. 16.77 ± 6.40 mm2). There were weak to negligible associations (tau = -0.229 to <0.001, P = 0.054-1.00) between individual qMRI biomarkers and clinical assessments of HGCs and EMG. qMRI changes in the SAM were observed in subjects with PTS involving the LTN. 2 TECHNICAL EFFICACY: Stage 1.

High-precision wave height detection of triboelectric nanogenerator by using voltage waveforms and artificial neural network

As we known waves contain important information, however, to realizing high-precision quantification for ocean exploitation and utilization is challenging. In this paper, we proposed a neural network for wave height detection by training the voltage waveform of a triboelectric nanogenerator (TENG). First, we analyzed the voltage signal obtained using a TENG. Second, we proposed a lightweight artificial neural network model that achieves a minimal monitoring error of 0.049% at low amplitudes and yields better monitoring results than the linear model. The findings presented in this paper enable the measurement of water surface waves and eliminate the influence of external factors on sensor performance. Wave parameters can be obtained using neural networks, and this work provides a new strategy for computational and intelligent applications by using wave data.

Studying inner core and lower mantle structure with a combination of PKP and converted SKP and PKS waves

SUMMARYStructure of the inner core is often measured through traveltime differences between waves that enter the inner core (PKPdf) and waves that travel through the outer core only (PKPab and PKPbc). Here we extend the method to converted waves PKSdf and SKPdf and compare results to PKP wave measurements. PKSdf and SKPdf have a very similar path to PKPdf and if velocity variations are present in the inner core, all three wave types should experience them equally. Since traveltime deviations can be due to velocity changes (either isotropic or anisotropy) as well as wave path deviations born from heterogeneity, we simultaneously investigate wave path directions and traveltimes of PKP, SKP and PKS waves for several source-array combinations. One of the path geometries is the anomalous polar corridor from South Sandwich to Alaska, which has strong traveltimes anomalies for PKPdf relative to more normal equatorial path geometries. Here we use array methods and determine slowness, traveltime and backazimuth deviations and compare them to synthetic data. We find that path deviations from theoretical values are present in all wave types and paths, but also that large scatter exists. Although some of the path deviations can be explained by mislocation vectors and crustal variations, our measurements argue that mantle structure has to be considered when investigating inner core anisotropy. Our polar path data show similar traveltime residuals as previously published, but we also find slowness residuals for this path. Interestingly, SKPdf and PKSdf for the South Sandwich to Alaska path show traveltime residuals that are partly opposite to those for PKPdf, possibly due to an interaction with a localized ultra-low velocity zone where waves enter the core.

Particle filter-based damage prognosis using online feature fusion and selection

Damage prognosis generally resorts to damage quantification functions and evolution models to quantify the current damage state and to predict the future states and the remaining useful life (RUL). The former typically consists of a function describing the relationship between the damage state and a statistical feature extracted from the measured signals, thus the prognostic performance will strongly depend on the selection of a proper feature. Given the best feature may vary for different specimens or even at each time instant for the same specimen during damage progression, such selection is a challenging task but has received little investigation so far. In this context, this paper proposes a particle filter-based damage prognosis framework, which involves an online feature fusion and selection scheme. A prognostic model is considered for each feature, with a multivariate process equation, formulated using both a damage degradation function and a bias parameter, and a measurement equation linking the damage state and that feature considering a data-driven model and the bias. One PF is used to estimate the damage state, its evolution parameters, and the bias for each model. Then, at each step, the feature with the smallest estimated bias is selected as the best feature providing the most likely state vectors and is used to select the most likely samples of the damage state and growth parameters for predicting the RUL and for calculating the prior at the next step. The proposed prognostic framework is demonstrated by an experimental study, where an aluminum lug structure subject to fatigue crack growth is monitored by a Lamb wave measurement system.

The diagnostic performance of salivary gland ultrasound elastography in Sjögren's syndrome and sicca symptoms: a systematic review and meta-analysis.

To systematically evaluate the diagnostic performance of ultrasound elastography (USE) in distinguishing primary Sjögren's syndrome (pSS) from healthy/disease controls. We searched the PubMed, Embase, Web of Science, and Cochrane Library databases for published literature on USE for diagnosing pSS. Bivariate random effects models were used to calculate the pooled sensitivity and specificity of USE. To determine the factors influencing heterogeneity, meta-regression and subgroup analyses were performed to assess country, diagnostic criteria, imaging mechanisms, shear wave elastography techniques, measurement location, control group category, and patient age. Publication bias was assessed using the asymmetry of the Deeks funnel plot. Fifteen articles covering 816 patients and 735 control participants were included. USE showed a pooled sensitivity of 0.80 (95% CI: 0.71-0.87) and specificity of 0.87 (95% CI: 0.78-0.92). Meta-regression and subgroup analyses revealed that shear wave elastography techniques, measurement location, and patient age were significant factors that affected study heterogeneity (p < 0.05). Elastography performs better in diagnosing patients aged ≤ 51years compared to patients aged > 51years. There was no significant publication bias. USE demonstrates high accuracy in differentiating between pSS and healthy/disease control groups. Ultrasound elastography, as a non-invasive and cost-effective technique, can be used to distinguish primary Sjögren's syndrome from disease/healthy control groups by measuring the stiffness of salivary glands. • Ultrasound elastography is an acceptable technique for the diagnosis of primary Sjögren's syndrome. • The pooled sensitivity and specificity of ultrasound elastography for diagnosing primary Sjögren's syndrome were 0.80 and 0.87, respectively. • In patients aged ≤ 51years with primary Sjögren's syndrome, ultrasound elastography showed good diagnostic performance.

Turbine fatigue load prediction from field measurements of waves and turbulence

The interest in this work is understanding the conditions which contribute to the cyclic loading experienced by a tidal turbine. Tidal turbines are placed in locations with high flow speeds in order to extract maximum kinetic energy. These flow speeds combined with other environmental factors can lead to a complex operating conditions. When assessing turbine loading across a site, most models use ambient flow conditions, with very few codes including the impact of waves with currents. Previous studies have analysed the influence of wave conditions from measurements on the loading, through a consideration of the turbine not operating. Although tidal conditions are bi-directional, wave conditions do vary with direction and this combination will be investigated in this study.&#x0D; Full-scale site data was gathered at Le Raz Blanchard, a potential tidal site as part of the Interreg funded TIGER project. The focus in this study is on data gathered which provides both wave and current conditions over a period of 45 days. Loading on the turbine components is assessed through an efficient blade element momentum theory method, which is combined with a synthetic turbulence model to provide a time-varying onset flow. This work determines the impact of the measured waves, and the way in which they are analysed on the turbulence characteristics in the onset flow, specifically the interaction of waves with current and influence on the loading experienced on the turbine.

Applications of remote sensing and near-surface geophysical methods for the investigations of a morainic ridge susceptible to landslide. A case study from the high lands of the Himalayas, Pakistan

Numerous factors are necessary to comprehensively comprehend the complex phenomenon of landslides and, ultimately, facilitate effective measures for their protection and management. This paper investigates the case history of the Maicher landslide in the Nagar District (Northern Pakistan) by using a multidisciplinary combined technique approach based on conventional geophysical measurements and modern remote sensing techniques. The first technique is to identify the rate of deformations with real-time landslide monitoring sensors and satellite images. Care is devoted to data acquisition and processing using the ad-hoc methodology to minimize errors and ensure high reliability. For the second technique (electrical resistivity tomography, surface waves measurements, and ground-penetrating radar), convenient methods for landslide characterization are used and herein presented. The combination of information taken from the different techniques allows the results to be validated by conventional and modern approaches and enhances the accuracy of each method. The results suggest that shear surface planes at a depth of 35–40 m have developed over time. The analysis also provided information on controlling factors and possible expansion of the different slope sections. This work highlighted that geophysical parameters (shear wave velocity Vs, dielectric constant ε, and resistivity value ρ) could provide reliable qualitative and quantitative information about the shallow layer, bedrock contacts, possible sliding surface and subsurface water saturation, and seepage system of a landslide. The geophysical results reflect an overview of the geological model and are effective in terms of the slope stabilization process.

Assessing wave-turbulence separation from ADCP measurements with artifical flow data

Accurate assessment of marine currents is critical for meaningful planning of tidal stream energy deployments. Methods for assessing mean flow speed are well-established, but the issue of assessing phenomena that vary over much shorter time scales than the semidiurnal tide (principally turbulence and waves) is not as settled. This is in part due to the limitations of the standard instruments used for surveying currents at potential tidal stream sites i.e., acoustic Doppler current profilers (ADCPs). Because ADCPs use multiple acoustic beams to sample single components of velocity at widely-separated spatial locations, a reliable analysis of the mean flow can be obtained by a suitable average over measurements from all beams: this approach works well for determining mean flow properties, but is less well-suited for the smaller and faster variations associated with waves and turbulence. In particular, conventional analysis approaches such as the variance method do not meaningfully distinguish between wave-driven and turbulence-driven velocity variations.&#x0D; An important consequence of this is that ADCP estimates of turbulent kinetic energy (TKE) are biased high because the TKE calculation method includes wave-driven velocity fluctuations as well as those caused by turbulence. Previous work by the authors has successfully applied a mixed spectral-statistical filter to ADCP estimates of TKE from a tidal stream test site; this filter showed good performance in distinguishing between true TKE and pseudo-TKE due to wave action. However, for field data it is only possible to assess the filter’s performance with respect to wave properties: this is because independent measurements of wave properties can be obtained from a surface buoy, but there is no alternative instrumentation that can yield independent measurements of turbulence.&#x0D; The study presented here addresses this shortcoming by generating an artificial flowfield with known turbulence and wave properties, sampling with a virtual ADCP, and applying the spectral-statistical filter to the results. In this way it is shown that the combined filter improves the separation of waves and turbulence over the individual filters by an even greater degree when assessed against turbulence data rather than against independent wave measurements. The study discusses the effects of different artificial turbulence generation schemes, specifically contrasting the spectral or Sandia method with the synthetic eddy method; it also discusses the tuning of spectral filter parameters for optimum separation of wave and turbulence effects.

COASTAL WAVE OVERTOPPING: NEW NOWCAST AND MONITORING TECHNOLOGIES

It is projected that global mean sea level could rise up to 1 m this century with a strong regional pattern. It is estimated that 20percent of England’s coastal defenses could fail under just half this rise. Ambitious climate mitigation and adaptation plans may protect 400,000 – 500,000 people, but flood and coastal erosion risks cannot be fully eliminated. Building coastal climate resilience requires accurate wave overtopping prediction tools and nowcast information to prepare for and respond to coastal hazards. In Dawlish, SW England, a new monitoring system to measure concurrent beach level and wave overtopping conditions over a 1-year period was installed. The system obtains in-situ measurements of the inland wave overtopping distribution across a public walkway and railway line, and issues near real-time overtopping data to the British Oceanographic Data Centre, making it accessible online within 15 minutes of detection. This public web service also ingests near-real time wave and water level data from existing national coastal monitoring networks, providing a full dataset to validate and calibrate an operational wave, water-level and overtopping forecast system. Using these data, the numerical forecasts have been refined by incorporating recent beach levels to reduce the uncertainty in the wave overtopping predictions due to seasonal variability in the beach level at the toe of the sea wall.

Contributed Session II: Detecting subclinical keratoconus by mapping corneal biomechanics using wave-based optical coherence elastography.

The detection of subclinical keratoconus in human corneas remains a challenging task. It is hypothesized that the focal reduction in biomechanical properties of the cornea would be the primary initiating event of keratoconus before changes in topography and pachymetry are manifested. We propose to use an air-couple ultrasonic optical coherence elastography system to map the elasticity of the corneas of 15 patients with a clinical diagnosis of keratoconus (KC) in one eye, and subclinical keratoconus (SK) in the fellow eye. The fully non-contact system excites the corneal apex to produce Lamb wave propagation and measures wave speed and average corneal thickness along 16 semi-meridians. Measurements in 30 human healthy subjects (control group: CG, N = 60 corneas) defined a baseline of normal biomechanics in two biomarkers: Spatial Anisotropy of Wave Speed (SAWS < 0.207), and the Speed-Thickness Index (STI > 0). SAWS was significantly higher in KC (0.353, p < 0.001) and SK (0.249, p < 0.001) corneas when compared to the CG. Moreover, STI maps show abnormal elasticity in SK (STI = -1.22) and KC (STI = -0.375) compared to the CG. Our results show important biomechanical differences in SAWS and STI between normal, subclinical, and advanced stages of keratoconus, suggesting those as potential biomarkers to identify "at-risk" corneas before changes in topography and pachymetry become evident.

Development of an ultrasonic wave measurement device based on Fiber Bragg Gratings in optical fibers: application to Guided Wave Structural Health Monitoring

Optical fiber transducers such as Fiber Bragg Gratings (FBG) are promising solutions for guided waves Structural Health Monitoring (SHM) due to their low intrusivity and their ability to cope with harsh environments (extreme temperatures, radiations, explosive atmospheres…). We present here a solution enabling measurements under varying environmental and operational conditions, which is mandatory for many applications in SHM, the low complexity of the solution ensuring good integration capacities. The effect of the length of the FBG was also studied to enable the optimization of the system sensitivity.

MAXIMUM MOMENTUM FLUX FOR STABILITY ANALYSIS OF MODEL AND PROTOTYPE BREAKWATERS

None of the established formulae for breakwater armour stone stability, Hudson (1958) or van der Meer (1987), explicitly account for the water depth at the toe of the structure. More recently, Hughes (2004), Melby and Hughes (2004), Melby and Kobayashi (2011) have developed equations for stability and runup utilising the concept of wave momentum flux which explicitly accounts for the water depth of the wave probe(s) in close proximity to the structure. The equations are adapted to three forms; namely (1) linear, (2) extended-linear and (3) non-linear. In the paper linearity is assessed by using the Ursell number at each probe depth. Also, due to the placement of probes at various depths in MHL’s 2D wave flume it is possible to correlate the linearity of the wave measurement for the same time series and subsequently test the appropriateness of the momentum flux equation applied for assessment of stability and runup. The stability and runup data from 43 2D physical model tests where stability was previously assessed using van der Meer’s and Hudson’s equations are assessed using the momentum flux equations and an evaluation of the results has been made. It was found that the estimation of notional permeability and selection of the use of the plunging or surging formulae was critical to obtaining a closer match between measurement and prediction. The equations were also utilised in conjunction with numerical models to evaluate the armour size for repair of two breakwater heads in South Camden Haven and Bellambi. The maximum momentum flux equations were found to perform satisfactorily at these locations where the Ursell numbers were found to be high and the waves non-linear.

ON THE PROBABILITY OF UNIDIRECTIONAL NONLINEAR EXTREME WAVES IN THE PRESENCE OF WAVE REFLECTION

Extreme waves are known to appear in different water depth regimes, and their focusing mechanisms have been intensively studied over the last decades. This experimental study aims to improve understanding of rogue wave statistics when wave reflections are at play. A series of unidirectional JONSWAP wave trains have been generated in a wave flume while varying the water depth and beach inclination slope. The data collected near the beach installation suggests a general decrease in extreme wave probability with the increase of the beach inclination, thus, with the increase of wave reflection. In deep-water, the numerical simulations based on the coupled nonlinear Schrodinger equation, which accounts for the presence of reflective waves, show a very good agreement with the experimental data. The irregular wave measurements in the presence of wave reflection indicate that the decrease in probability of exceedance, which correlates with the decrease in the value of kurtosis, is due to the weakening of third-order effects. When the water depth is decreased to a finite depth regime, we can observe an increase of extreme events, which we attribute to the change of the wave breaking threshold. However, no substantial rogue waves have been observed below the dimensionless depth kh value of 1.36. Then again, nonlinear effects always remain relevant and at play in all cases considered.

Probing the Foreshock Wave Boundary With Single Spacecraft Techniques

AbstractIn space physics, wave measurements typically use a small number of datapoints due to limited available spacecraft. Common single‐spacecraft wave vector analysis techniques built around these limitations are widely used, even in regions where the wave amplitude profile may have a strong spatial dependence. We show that in these gradient regions, the divergence‐free condition of the magnetic field requires a local modification to the plane of polarization that is incorrectly interpreted by single‐spacecraft techniques. We explore the consequences of this result in the Earth's ion foreshock using both Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon’s Interaction with the Sun spacecraft data and a 2.5‐D hybrid Vlasov simulation conducted using the Vlasiator code. The observed foreshock ultralow frequency waves have a finite extent in the direction perpendicular to the Interplanetary Magnetic Field, and incorrect application of standard minimum variance techniques at the boundary yields a false wave vector orientation that may be used as a novel edge detection method. This method may be particularly useful for analysis of the ion foreshock at other planets where only a single spacecraft is available. More broadly, our results stand as a cautionary tale for wave analysis in other space physics contexts where the wave geometry is less clear.

Physical Model Experiment for Estimating Wave Overtopping on a Vertical Seawall under Regular Wave Conditions for On-Site Measurements

Apart from implementing hardware solutions like raising the crest freeboard of coastal structures to efficiently counter wave-overtopping, there is a simultaneous requirement for software-driven disaster mitigation strategies. These tactics involve the swift and accurate dissemination of wave-overtopping information to the inland regions of coastal zones, enabling the regulation of evacuation procedures and movement. In this study, a method was proposed to estimate wave-overtopping by utilizing the temporal variation of wave heights exceeding the structure’s crown level, with the aim of developing an on-site wave measurement system for providing wave-overtopping information in the field. Laboratory model experiments were conducted on vertical seawall structures to measure wave-overtopping volumes and wave runup heights under different wave conditions and structural freeboard variations. By assuming that the velocity of water inundation on the top of the structure during wave-overtopping events is equivalent to the long-wave velocity, an overtopping discharge coefficient was introduced. This coefficient was utilized to estimate the rate of wave-overtopping based on the temporal changes in wave runup heights measured at the top of the structure. Upon reasonably calculating the overtopping discharge coefficient, it was verified that the estimation of wave-overtopping could be achieved solely based on the wave runup heights.

One-dimensional regional shear velocity structure from joint inversion of fundamental mode group velocity dispersion measurements of Love and Rayleigh waves: application to the Uttarakhand Himalaya

One-dimensional regional shear velocity structure from joint inversion of fundamental mode group velocity dispersion measurements of Love and Rayleigh waves: application to the Uttarakhand Himalaya

The Use of Quantitative Electroencephalography (QEEG) to Assess Post-COVID-19 Concentration Disorders in Professional Pilots: An Initial Concept.

Announced by WHO in 2020, the global COVID-19 pandemic caused by SARS-CoV-2 has affected many people, leading to serious health consequences. These consequences are observed in the daily lives of infected patients as various dysfunctions and limitations. More and more people are suffering post-COVID-19 complications that interfere with or completely prevent them from working or even functioning independently on a daily basis. The aim of our study was to demonstrate that innovative quantitative electroencephalography (QEEG) can be used to assess cognitive function disorders reported after the COVID-19 pandemic. It is worth noting that no similar study has been conducted to date in a group of pilots. The QEEG method we used is currently one of the basic neurological examinations, enabling easy observation of post-COVID-19 changes in the nervous system. With the innovativeness of this technique, our study shows that the use of quantitative electroencephalography can be a precursor in identifying complications associated with cognitive function disorders after COVID-19. Our study was conducted on twelve 26-year-old pilots. All participants had attended the same flight academy and had contracted SARS-CoV-2 infection. The pilots began to suspect COVID-19 infection when they developed typical symptoms such as loss of smell and taste, respiratory problems, and rapid fatigue. Quantitative electroencephalography (QEEG), which is one of the most innovative forms of diagnostics, was used to diagnose the patients. Comparison of the results between the study and control groups showed significantly higher values of all measurements of alpha, theta, and beta2 waves in the study group. In the case of the sensorimotor rhythm (SMR), the measurement results were significantly higher in the control group compared to the study group. Our study, conducted on pilots who had recovered from COVID-19, showed changes in the amplitudes of brain waves associated with relaxation and concentration. The results confirmed the issues reported by pilots as evidenced by the increased amplitudes of alfa, theta, and beta2 waves. It should be emphasized that the modern diagnostic method (QEEG) presented here has significant importance in the medical diagnosis of various symptoms and observation of treatment effects in individuals who have contracted the SARS-CoV-2 virus. The present study demonstrated an innovative approach to the diagnosis of neurological complications after COVID-19.

Baseline Measurements of Waves and Currents along the Coast of Oman

The coast of Oman is undergoing huge coastal developments in order to realize Oman Vision 2040, covering all the strategic sectors. Historical data of coastal hydrodynamic parameters is scarce, even though its importance for properly designed coastal structures is recognized. In the present study, Acoustic Doppler Current Profilers (ADCP) were deployed at eleven locations along the coast of Oman. These locations were selected based on their strategic importance for the country. The duration of the deployments were between 60 and 265 days. The measured data of the waves and currents were collected and analyzed using equipment-specific software and Excel. The significant wave heights can reach 2 m along the whole coast of Oman. The southern coast is dominated by swells. The maximum to significant wave height ratio is approximately 1.5, which is less than the value of 2 obtained using the Rayleigh distribution. The coastal currents are stronger along the southern coast than those along the northern coast. The range of current magnitude is between 0.02 m/s and 0.8 m/s. This baseline study will help the public authorities in establishing permanent hydrodynamic measurement stations along the coast of Oman. Moreover, these measurements will serve the practicing engineers in designing coastal structures along the coast of Oman.

Evaluating vessel technical performance index using physics-based and data-driven approach

Ship's performance and its emissions are affected by several factors like operational state, weather, and maintenance condition. Rating ships with performance indices, such as AER, is not really helpful as these factors are affected by the ship's technical and operational condition, obscuring the benefits of energy-saving technologies and improved maintenance condition. To promote energy-efficient ships and reduce emissions, DNV proposed a simple and intuitive Vessel Technical Index (VTI) which is expected to represent the change in technical performance of ships over time. This paper presents two different schemes to estimate VTI, namely, physics-based and data-driven approaches, to validate their applicability as well as compare their performance. The results are based on the measured in-service data from a bulk carrier, equipped with advanced sensors for speed and wave measurements. Although the VTI values from the data-driven approach are slightly overestimated, the mean trend of VTI over time, representing the change in performance of the ship, is quite comparable. The uncertainty in the results is reduced almost by half using the measured wave spectrum for physics-based VTI, whereas the data-driven approach creates an opportunity for ship performance monitoring without the need for speed-through-water measurements, which are considered unreliable for most ships.