Swell Conditions Research Articles

Prediction of volatile composition of coal pyrolysis under various swelling and catalytic conditions based on recurrent neural network

Solvent swelling and catalyst have significant effects on the volatile release behavior during coal pyrolysis process, not only affecting the total amount, but also affecting the release trend when the temperature rises. An accurate quantification of this relationship can promote the efficient utilization of pyrolysis volatiles. This work adopts machine learning (ML) methods to construct prediction models for four primary volatiles (CO, CH4, aromatic and aliphatic hydrocarbons) during the pyrolysis of coal samples treated by different metal loading and solvent swelling, to predict the instantaneous volatile content at any time in the pyrolysis process. The deep learning models constructed by Recurrent neural networks (RNN) were compared with traditional machine learning methods of artificial neuron network (ANN), random forest (RF) and support vector machine (SVM), and realized an obvious preponderance on prediction performance for hole release curve. The best long short-term memory (LSTM) models achieve the average R2 of 0.978, 0.900, 0.950 and 0.936 for the release curve prediction of CO, CH4, aromatic and aliphatic volatile. Further adjustments shown that the reduction of sampling points on curves has little effect on the model’s performance, which makes it feasible to condense the models and decrease the dimensions of input. An easy signal processing of integral transformation had an obvious improvement on the predictive power of models, with a highest increase of R2 with 0.14 for aromatics predicting. All of these results provide a good method for real-time tracking of the conversion process.

A hydromechanical material model for compacted bentonite

This paper presents a new hydromechanical model, developed with the intention to be used for predicting the mechanical evolution of compacted bentonite components in repositories for spent nuclear fuel. The model is based on a thermodynamic relation for the chemical potential of the clay water, and uses empirical functions which are parametrized and calibrated with data on water retention properties at free swelling conditions, swelling pressure, and shear strength; the latter two are central for defining technical requirements for the bentonite buffer components. This results in a model which at its core incorporates all these properties, as well as the hysteresis behaviour. The validity of the model was investigated by analysing nine experimental test conditions, using COMSOL Multiphysics®, with a single set of parameter values. Model results were compared with experimental data for both saturated conditions (free swelling retention test; oedometer tests and triaxial compression tests) and for unsaturated conditions (swelling pressure build-up; swelling or shrinkage at constant load; compression at constant water or constant suction and unconfined compression tests). These comparisons gave a broad demonstration of the predictive capabilities of the model. Some limitation of the model regarding the representation of shrinkage, the shear strength at lower water contents, and the path dependence can nevertheless be noted.

OBSERVATION AND NUMERICAL MODELING OF A DUNE OVERWASH AND BREACHING EVENT

Sea level rise will significantly increase the need for building and upgrading coastal protection such as artificial coastal dunes or berms (Wong et al., 2014). Human constructed dunes are frequently deployed to limit wave runup and overtopping and mitigate damage from flooding events (e.g., Gallien et al., 2015). Although dune erosion modeling and validation on storm surge dominated beaches is common in the literature, only limited work considers energetic long period swell conditions typical of coastal California. In this study three morphological models are used to simulate dune erosion response to long period swell and compared to high resolution in-situ hydromorphological field observations.

Attaining consensus on a core dataset for upper limb lymphoedema using the Delphi method: A foundational step in creating a clinical support system.

Background: Lymphoedema is a condition of localised swelling caused by a compromised lymphatic system. The protein-rich fluid accumulating in the interstitial tissue can create inflammation and irreversible changes to the skin and underlying tissue. An array of methods has been used to assess and report these changes. Heterogeneity is evident in the clinic and in the literature for the domains assessed, outcomes and outcome measures selected, measurement protocols followed, methods of analysis, and descriptors used to report change. Objective: This study seeks consensus on the required items for inclusion in a core data set for upper limb lymphoedema to digitise the monitoring and reporting of upper limb lymphoedema. Methods: The breadth of outcomes and descriptors in common use were captured in prior studies by this research group. This list was refined by frequency and proposed to experts in the field (n = 70) through a two-round online modified Delphi study. These participants rated the importance of each item for inclusion in the dataset and identified outcomes or descriptors they felt were missing in Round 1. In Round 2, participants rated any new outcomes or descriptors proposed and preference for how numeric data is displayed. Results: The core dataset was confirmed on completion of Round 2. Interlimb difference as a percentage, and limb volume were preferred for graphed display over time; and descriptors for observed and palpated change narrowed from 42 to 20. Conclusion: This dataset provides the foundation to create a clinical support system for upper limb lymphoedema.

A comprehensive computer-aided system for an early-stage diagnosis and classification of diabetic macular edema

Diabetic macular edema (DME) is a condition of retinal swelling due to the accumulation of leaked plasma in the extracellular space in the retina, known as the macula. DME is a chronic progressive retinal disorder that likely results in permanent complete blindness. The early signs of DME are not discernible by merely suspecting the fundus picture with the naked eye. Therefore, a computer-assisted diagnostic system could aid ophthalmologists in screening, diagnosing, and treating DME. This study proposes an efficient and complete model for early diagnosis and staging of DME. To overcome the challenges in precise localization of fovea, blood vessel network extraction, and accurate lesion segmentation, improved image relative subtraction, Gabor wavelet filter, and novel advanced fuzzy c-means clustering algorithms are introduced, respectively. Finally, the Bayesian classifier using the Gaussian function with expectation maximization is used for DME grading. The accurate optic disc and fovea localization, exudates’ segmentation, and classification improved the overall system’s performance. The proposed model achieves an average accuracy of 96.17%, 98.60%, 97.85%, and 98.80% for optic disc detection, fovea localization, exudates segmentation, and DME classification, respectively. The performance of the proposed model compared to the competitive studies illustrates the superiority of the suggested methodology.

Effect of sea states on the wind velocity fluctuations near the surface under near-neutral conditions

This study examines the effect of sea states on wind velocity fluctuations in the longitudinal direction near the sea surface under near-neutral stratification, characterized by inverse wave age. The analysis is based on wind and wave data collected from a discus buoy measurement off the coast of Taiwan in the Taiwan Strait. It is observed that wind waves and swells modify the overlying turbulence structure differently. In particular, wind-swell coupling results in greater variations and values of the scaled velocity standard deviation and turbulence intensity with increasing wind speed, as well as a more pronounced peak in the scaled wind velocity spectrum compared to pure wind sea conditions. The spectral shapes averaged for pure wind sea and swell conditions are described by a plateau followed by a wave-induced peak in the intermediate-frequency range. These features suggest that near-surface turbulence is driven by eddy impingement on the sea surface, associated with wave-induced fluctuations in the lower part of the eddy surface layer. The study has practical applications in evaluating the wind loads on offshore structures, particularly in the context of offshore wind energy development.

Comparative Performance of Radar, Laser, and Waverider Buoy Measurements of Ocean Waves. Part II: Time-Domain Analysis

Abstract Accurate measurements of ocean waves underpin efficient offshore operations and optimal offshore structure design, helping to ensure the offshore industry can operate both safely and economically. Popular instruments used by the offshore industry are the Rosemount WaveRadar (Radar) and the Waverider Buoy. The Optech Laser has been used at some locations for specific studies. Recent reports indicate systematic differences of order 10% among the wave measurements made by these instruments. This paper examines the relative performance of these instruments based upon various time-domain comparisons, including results from a quality control (QC) procedure, capabilities of measuring the wave surface profile (skewness), and crest heights for varying wind sea and swell conditions. The QC check provides good-quality data that can be further investigated with an assurance of error-free data, suggesting that the Waverider produces the best-quality data with the lowest failure rate compared to the Laser and Radar. A significant number of the Waverider surface elevation records have negative skewness, particularly at higher sea states, affecting its crest height measurements, which are lower than those from the Laser and Radar. Additionally, the significant wave height (H1/3) estimates of the Radar are lower than the Laser and Waverider, but its zero-crossing wave periods (TZ), on average, are longer than the Laser and the Waverider. The significant heights (H1/3) of Laser and Waverider are in good agreement for all three datasets, but the Waverider’s zero-crossing wave period (TZ) estimates are significantly longer than the Laser.

Comparative Performance Study of DVR Using Adaptive LMS Filtering-Based Algorithms

In the distribution system, voltage sags and swell have adverse effects on sensitive and critical loads. Dynamic Voltage Restorer (DVR) play a vital role to mitigate voltage sags and swell through its organized control when connected in series with the system. Various conventional control schemes have been reported for the control of DVR. The performance of DVR with these schemes has been successful in the mitigation of voltage sags/swell, but drawbacks, such as undershoot, and overshoot during sag dynamics are observed in the regulated load terminal voltage. These drawbacks may cause malfunctioning of the equipment connected and hence their elimination is indispensable. With this inspiration, a novel Adaline filter-based adaptive control scheme using learning-rate parameter-based Least-Mean-Square algorithm has been proposed. This scheme has the capability to overcome the drawbacks with the conventional control schemes thus improving the performance of DVR. In this paper, the performance of DVR using proposed algorithm is compared with that using synchronous reference frame (SRF)-based conventional control scheme. The performance is studied and validated through simulation results under different voltage sag and swell conditions in MATLAB software using Sim Power System toolboxes.

Water and soil particle movement in unsaturated bentonite with constrained and free swelling boundaries

Bentonite is considered a barrier material in the geological disposal of high-level radioactive waste. Depending on the construction method, it is necessary to know what the behavior of the bentonite barrier will be in the wetting process during the absorption of underground water under different boundary conditions. In this study, water and soil particle movement during the wetting process of a compacted bentonite under constrained and free swelling conditions was studied experimentally and numerically. For the constrained swelling boundary condition, in which the swelling deformation was fully constrained, the distributions of the gravimetric water content (w) were measured for specimens with different dry densities (ρd), and then the water diffusivity (Dw) was obtained. It was found that Dw showed a slightly decreasing trend with an increase in ρd, while the numerical simulations showed that the difference in Dw induced by ρd was minor in terms of the evolving degree of saturation in the tested range. For the free swelling boundary condition, the distributions of w and ρd were measured for specimens with an initial ρd of 1.6 Mg/m3. To obtain Dw and the soil particle diffusivity (Ds), an existing theoretical framework, to which new concrete calculation equations had been added, was presented. Then, the performance of the framework was examined by numerical simulations to illustrate the water and soil particle movement under conditions similar to those of the experiment. It was found that the framework can describe the experimental results well, but that the accuracy of the results largely depends on the accuracy of the experimental data.

A Novel Prairie Dog-Based Meta-Heuristic Optimization Algorithm for Improved Control, Better Transient Response, and Power Quality Enhancement of Hybrid Microgrids.

The growing demand for electricity driven by population growth and industrialization is met by integrating hybrid renewable energy sources (HRESs) into the grid. HRES integration improves reliability, reduces losses, and addresses power quality issues for safe and effective microgrid (MG) operation, requiring efficient controllers. In this regard, this article proposes a prairie dog optimization (PDO) algorithm for the photovoltaic (PV)-, fuel cell (FC)-, and battery-based HRESs designed in MATLAB/Simulink architecture. The proposed PDO method optimally tunes the proportional integral (PI) controller gain parameters to achieve effective compensation of load demand and mitigation of PQ problems. The MG system has been applied to various intentional PQ issues such as swell, unbalanced load, oscillatory transient, and notch conditions to study the response of the proposed PDO controller. For evaluating the efficacy of the proposed PDO algorithm, the simulation results obtained are compared with those of earlier popular methodologies utilized in the current literature such as bee colony optimization (BCO), thermal exchange optimization, and PI techniques. A detailed analysis of the results found emphasizes the efficiency, robustness, and potential of the suggested PDO controller in significantly improving the overall system operation by minimizing the THD, improving the control of active and reactive power, enhancing the power factor, lowering the voltage deviation, and keeping the terminal voltage, DC-link voltage, grid voltage, and grid current almost constant in the event of PQ fault occurrence. As a result, the proposed PDO method paves the way for real-time employment in the MG system.

Effect of Swelling Soil on Load Carrying Capacity of a Single Pile

Expansive soils are recognized by their swelling potential upon wetting due to the existence of some clay minerals such as montmorillonite. An effective solution was found to avoid the danger of such soils by using piles. A single pile embedded in an elasto-plastic expansive soil has been analyzed by using one of the available software which is ABAQUS to investigate the effect of applied loads on pile’s top and investigate the effect of swelling soils on load carrying capacity of the pile. The result shows that as the pile is axially loaded at its top, the axial force along the pile gradually changes from (tension) to (compression) and the pile tends to move downward. The applied load needed to initiate pile’s settlement depends on pile’s embedment depth and the depth of active zone. The ultimate carrying capacity of a single pile for no swelling conditions is greater than that of with swelling conditions.

Swelling behavior of divalent and monovalent Indian bentonites in isochoric and free swelling conditions

Swelling behavior of divalent and monovalent Indian bentonites in isochoric and free swelling conditions

Power Quality Enhancement in Solar PV and Battery Integrated UPQC Grid Connected System

This paper discusses a distributed generation system consisting of grid-connected solar PV and a battery-integrated Unified Power Quality Conditioner (UPQC). Embedded in the PV array, the UPQC consists of a series and shunt converter connected back through a common DC link. In this system, power quality problems of clean energy, such as harmonics, voltage drops, ripples, are compensated by injecting active energy into the power grid. The shunt converter is controlled to maintain a constant DC link voltage and harmonic compensation of the load current. The main voltage problem is compensated by a series converter that injects the voltage during sag and swell. The advantages of integrating renewable energy sources and enhancing power quality are brought together in this system. The performance of the system is analyzed during voltage sag, swell condition and under unbalance condition for nonlinear load along with power flow analysis through the enhancement of dc bus voltage. Finally, the simulation results are shown for the estimation of dynamic performance of PV, battery integrated UPQC system during unbalanced condition

Uncovering the relationship between optic atrophy-1 protein and mitochondria function

Mitochondria, known as the powerhouse of the cell, also participate in the regulation of ion homeostasis, redox status, cell growth and differentiation, lipid metabolism, and cell death. The inner mitochondrial membrane (IMM) plays a crucial role in the regulation of mitochondrial metabolism and function. The dynamin-related GTPase optic atrophy-1 (OPA1) localized in the IMM is responsible for mitochondria fusion. In addition, OPA1 has been shown to play an important role in maintaining the structural integrity and functional activity of mitochondrial cristae. We have recently shown that mitochondrial swelling stimulates enzymatic cleavage of OPA1 by OMA1, a zinc metallopeptidase, which converts long-OPA1 (L-OPA1) to short-OPA1 (S-OPA1). Cleavage of L-OPA1 was suggested to diminish mitochondrial fusion and bioenergetics leading to cell death. The role of OPA1 cleavage and OMA1 activation under diverse swelling conditions has not yet been elucidated. In this study, we investigated the role of OPA1 cleavage under various mitochondrial swelling conditions in the presence and absence of Myls22 (an OPA1 inhibitor), and TPEN (a zinc-chelator and OMA1 inhibitor). Cardiac mitochondria were isolated from Sprague Dawley rats and their function was assessed under Ca2+-induced mitochondrial swelling with oxoglutarate and malate (OM) with/without ADP. Our dose-dependent experiments revealed that Myls22 and TPEN exert the maximum effect at 50 and 5 μM, respectively. Next, we found that the maximum respiration rate (state 3) of mitochondria for complex I is diminished by both inhibitors. However, neither Myls22 nor TPEN prevented alterations in mitochondrial respiration rates, swelling, membrane potential, and calcium retention capacity induced by Ca2+. Finally, we evaluated the protein expression of L-OPA1 via western blot and found more OPA1 cleavage under state 3 compared to state 2 respiration rate suggesting the regulatory role of S-OPA1 in mitochondrial respiration. Thus, our data demonstrate that although mitochondrial swelling stimulates L-OPA cleavage associated with mitochondrial dysfunction, inhibition of OPA1 cleavage/OMA1 activity by Mysl22/TPEN is ineffective in ameliorating the effects of Ca2+-induced mitochondria swelling. This study was supported by the National Science Foundation (Grant 2006477). This is the full abstract presented at the American Physiology Summit 2023 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.

Automated solid-phase synthesis of metabolically stabilized triazolo-peptidomimetics.

The use of 1,4-disubstituted 1,2,3-triazoles as trans-amide bond surrogates has become an important tool for the synthesis of metabolically stabilized peptidomimetics. These heterocyclic bioisosters are generally incorporated into the peptide backbone by applying a diazo-transfer reaction followed by CuAAC (click chemistry) with an α-amino alkyne. Even though the manual synthesis of backbone-modified triazolo-peptidomimetics has been reported by us and others, no procedure has yet been described for an automated synthesis using peptide synthesizers. In order to efficiently adapt these reactions to an automated setup, different conditions were explored, putting special emphasis on the required long-term stability of both the diazo-transfer reagent and the Cu(I) catalyst in solution. ISA·HCl is the reagent of choice to accomplish the diazo-transfer reaction; however, it was found instable in DMF, the most commonly used solvent for SPPS. Thus, an aqueous solution of ISA·HCl was used to prevent its degradation over time, and the composition in the final diazo-transfer reaction was adjusted to preserve suitable swelling conditions of the resins applied. The CuAAC reaction was performed without difficulties using [Cu (CH3 CN)4 ]PF6 as a catalyst and TBTA as a stabilizer to prevent oxidation to Cu(II). The optimized automated two-step procedure was applied to the synthesis of structurally diverse triazolo-peptidomimetics to demonstrate the versatility of the developed methodology. Under the optimized conditions, five triazolo-peptidomimetics (8-5 amino acid residues) were synthesized efficiently using two different resins. Analysis of the crude products by HPLC-MS revealed moderate to good purities of the desired triazolo-peptidomimetics (70-85%). The synthesis time ranged between 9 and 12.5h.

A self-similar description of the wave fields generated by tropical cyclones

Today, advanced operational wave models, e.g. WAM, SWAN or WAVEWATCH-III, provide very accurate solutions. Nevertheless, under extreme weather conditions, surface wave predictions can remain challenging. Indeed, for relatively small-scale tropical cyclones (TCs), rapidly evolving in time and space, and possibly not always well sampled with observing systems, extreme winds may not be properly described, and generated wave systems correctly predicted. In that context, Kudryavtsev et al. (2021b) recently proposed a simplified framework to rapidly assess evolving wave fields under typical TC conditions. Using self-similar functions, termed Tropical Cyclone-Wave Geophysical Model Function (TCW GMF), the proposed methodology and initial results demonstrate robustness and efficiency : 2D functions, assimilating a small number of parameters (maximum wind speed, cyclone radius and translation velocity), provide first-guess estimates of surface wave heights, wave lengths and directions within the intense TC core region. Following this strategy, an improved TCW GMF version is proposed to also cover the TC far zone, providing both wind wave information and outrunning swell conditions. This new version more particularly accounts for the wave field sensitivity to the shape of the wind profile. The procedure follows three main steps: (1) estimation of the characteristics of pure wind waves using self-similar matrices; (2) determination of the contour limiting the transition between wind waves to swell regime using empirically-derived universal functions; (3) derivation of analytical functions to describe the swell parameters using initial parameters estimated at this transition contour. Wind waves and swell systems are further superposed to describe the wave parameters for mixed-sea conditions. In this study, IBTrACS are used to initialize the TC’s wind profiles, coordinates and translation velocities. The proposed methodology is then tested using a large altimeter database. More than 700 altimeter measurements crossing different TCs during 2020–2022 years are used, demonstrating overall convincing agreements between first-guess estimates and satellite data.

Hybrid control mechanism-based DVR for mitigation of voltage sag and swell in solar PV-based IEEE 33 bus system

<p><span lang="EN-US">The power quality issues are raised due to sag/swell, which affects the overall performance of the grid-connected system. This study introduces the hybrid control mechanism based on a dynamic voltage restorer (DVR) to mitigate the sag and swell issues in the solar PV-based IEEE 33 bus system. The hybrid controller improves the dynamic performance and boosts the overall efficiency of the DVR system. The proposed work is also used to address the distribution system's voltage quality issues with minimal energy drawn out from the utility grid and effectively use solar energy. The sag and swell are introduced at the grid side and compensated at the load side by injecting DVR voltage. The proportional-integral (PI) controller followed by the fuzzy logic controller (FLC) is used to create the hybrid control mechanism for DVR. In this work, the solar PV system with DVR system is connected to the 29<sup>th </sup>location in the IEEE 33 bus system for performance realization. The hybrid control mechanism-based DVR provides 1.06% and 1.05% total harmonic distortion (THD) at sag and swell conditions for load voltage. The proposed work meets the IEEE 519 standards in terms of THD calculation. The proposed design compares with existing work and shows better THD reduction for load voltages.</span></p>

Finite Element Modeling and Simulation of a Submerged Wave Energy Converter System for Application to Oceanic Islands in Tropical Atlantic

The development of efficient and sustainable marine energy converter systems is a great challenge, especially in remote areas such as oceanic islands. This work proposes a numerical modeling methodology to assess the mechanical behavior of a wave energy converter (WEC) to be applied outside Fernando de Noronha Island (Pernambuco, Brazil). First, oceanographic data collected in situ were analyzed to determine different sea state scenarios in the region. The Airy theory and second-order Stokes’ theory were used to obtain the velocity profiles for the maximum and operational swells. These profiles were then implemented in a flow model developed in COMSOL Multiphysics software (Burlington, MA, USA) to calculate the wave distributions of pressure on the WEC structure. Finally, wave pressure distributions obtained from simulations were implemented in a static analysis of the system by the finite element method using SolidWorks (France). The results highlighted the most critical system inclination and the parts of the WEC structure more likely to be damaged under extreme swell conditions. The 0° inclination was the most critical situation, leading to the exceeding of the elastic limits of some parts of the WEC structure. The methodology developed in this work showed to be efficient to study and propose project improvement for the strength of the WEC system.

Application of Dynamic Voltage Restorer through HHO Algorithm for Safe and Sustainable Operation of Electrical Distribution System

The voltage dynamic recovers steady-state, transient, and dynamic responses by protecting electrical equipment against unbalances, swells, and voltage sags and provides safe operation. The existing control structures were successful in restoring steady voltage. However, the intrinsic oscillations fail to account for those that may occur while quitting the system and introducing the DVR. The work describes a simple control system for dealing with dynamic, steady-state, and transient responses and intrinsic fluctuations that provides safety and sustainability as well. This suggested control system uses an upstream disturbance detection signal as the feed-forward. The feed-forward term is accomplished by the closed loop for the feedback of the controlling signal, which decreases transient changes and enhances system response. The HHO algorithm, the most recent metaheuristic optimisation algorithm, is utilised. Using MATLAB-Simulink, the system is simulated. Performance analysis of the proposed HHO algorithm is evaluated under different SWELL and SAG conditions.

Emergency referrals to a paediatric dental A&E service in London: where do we stand post-pandemic?

Introduction The paediatric dentistry department at St Thomas’ Hospital transformed its walk-in emergency service to an urgent dental centre during the COVID-19 pandemic, accepting referrals via the NHS 111 service. There are conflicting ethical duties for tertiary care clinicians managing paediatric dental patients. This study measured the current activity levels of the dental emergency service at St Thomas’ Hospital, the appropriateness of NHS 111 referrals, the proportion of referrals accepted for care and the outcomes of those accepted referrals. Methods A retrospective service evaluation was undertaken including 125 patients referred by the NHS 111 service to the dental emergency clinic at St Thomas’ Hospital between 1 September and 29 October 2021. Results Half (50%) of the patients seen were aged between 0 and 5 years. A quarter (24%) of referrals were true dental emergencies. Patients were referred for isolated dental pain (58%), facial swelling (25%), trauma (13%), broken fillings (3%) and other conditions (2%). Three-quarters (74%) were accepted for treatment. Most accepted patients were added to waiting lists for treatment under general anaesthesia (66%), local anaesthesia (5%) or inhalation sedation (4%). Two-thirds of accepted patients (67%) were not registered with a dentist while over three-quarters of rejected patients (79%) had their own dentist in primary care. Conclusions Following the pandemic, paediatric dental emergency services continue to be overwhelmed by children requiring non-urgent dental care. Solutions to deteriorating patient access are crucial, ensuring that provision of care remains ethical and that those who require urgent dental care are prioritised.