Accurate Consideration Research Articles

Численное моделирование конвекции жидкого магния в аппарате восстановления титана с учетом эффективных граничных условий

We investigate the numerical problem of conjugate heat exchange between liquid magnesium, a steel retort, and the air-cooling zone of the titanium sponge reduction reactor furnace at the initial stages of production. The uneven distribution of heat fluxes on the side surface of the retort significantly affects the formation of convective turbulent flow inside the apparatus. The accurate consideration of thermal boundary conditions will make it possible to adequately solve the problem of heat and mass transfer in the reactor without using model representations of heat flows on the boundaries of the retort. The problem was solved in the axisymmetric nonstationary formulation using the k-ω SST turbulence model. In the numerical simulation, two conceptual solutions of the problem were implemented. The first one involves the end-to-end calculation in the framework of the coupled heat and mass transfer problem, with the calculations performed in all parts of the titanium reduction apparatus and thermal boundary conditions set on its outer boundaries. The second model relies on an effective thermal boundary condition that is applied to the outer boundary of the retort and excludes calculations in the cooling channel when investigating magnesium convection. The first model, due to its greater completeness, is more accurate, but requires considerable computational resources and time. The model with an effective thermal boundary condition, provided that the coefficients in it are selected appropriately, gives results qualitatively and quantitatively close to those obtained through end-to-end calculations. At the same time, such a model is more economical. The paper evaluates the possibility of applying an effective boundary condition. Convective flows of molten magnesium in the retort under different modes of blowing and heating have been studied. The influence of the radiation part of the heat flow on the formation of convective currents is shown.

Strategic priorities of the DRV and the US during the Second Indochina War

The article is devoted to the analysis of the strategic priorities of the DRV and the United States at the turning point and final stages of the Vietnam War. In the American army and historiography during the war and later an understanding of the origins of the Vietnamese strategy was not formed. First of all, the influence of Sun Tzu's treatise modernized by Ho Chi Minh was not taken into account. These approaches were creatively used by the Vietnamese command not only against the French, but also against the Americans during the war with the United States. Traditional Vietnamese strategic approaches created an effective counter-strategy against the American “search and destroy” strategy. Hanoi adopted a protracted war strategy for which the United States was unprepared. Accurate consideration of the advantages and disadvantages of both sides allowed Hanoi to seize the strategic initiative and implement a significant part of their schemes in an asymmetric war with a stronger enemy and finally achieve the withdrawal of American troops. In their struggle against the United States, the DRV skillfully and creatively used not only Soviet military equipment and the methods of its use in combat, but also the fundamental strategic principles of Sun Tzu, adapted to the conditions of modern warfare. After the Tet Offensive other strategic offensive operations followed again and again. From January 1968 to the spring of 1975, Hanoi carried out 5 major offensive operations in South Vietnam, which led to the defeat of the United States in the war.

Investigation and Classification of Chronic Wound Tissue images Using Random Forest Algorithm (RF)

The broad increase make use of digital cameras, by hand wound imaging has turn out to be common practice in experimental place. There is in malice of still a condition for a reasonable device for accurate wound curing consideration between dimensional facility and tissue categorization in a exacting simple to exploit technique We achieved the major unit of this plan by computing a 3-D model for wound dimensions using un calibrated revelation techniques. We highlight at this point on tissue classification from color and eminence region descriptors computed after unverified segmentation. As a result of perception distortions, unconstrained lighting provisions and viewpoints, wound assessments modify commonly in the middle of patient review. The majority significant separation of this article is to overcome this trouble by means of a multi inspection approach for tissue classification, relying on a 3-D model onto which tissue labels are mapped and categorization result merged. The investigational categorization tests communicate that improved repeatability and robustness are obtained and that metric assessment is attain through appropriate region and degree dimensions and wound chart origin. In this manuscript we proposed wound image segmentation, tissue classification in grouping with the Random Forest (RF). These methodology are helpful for classifying the rate of injured tissue in a segmented element and improved accuracy.

COMPARATIVE ANALYSIS OF COMPOSITE TIMBER-CONCRETE CEILING SYSTEMS

This paper compares two concepts of composite timber concrete ceilings and their uncoupled alternatives based on a parametric study by comparing the final deflections of individual variants and at the same time considering according to the ultimate limit state. It includes a comparison of coupled and uncoupled variants while maintaining the same boundary conditions as the load, the thickness of the ceiling structure and the load width. By considering other factors, we can achieve more optimal variant, thanks to more accurate consideration of the required boundary conditions such as the complexity of installation or fire resistance. The purpose of this paper is to simplify the optimal selection of the ceiling structure based on the suitability of the supporting structure.

Implementation of Exp-6 potential function in thermodynamic modeling of clathrate hydrates phase equilibria

Accurate modeling of clathrate hydrates phase behaviors is of significant importance to petroleum industry. It is well known that accurate consideration of the cavity force field can lead to more accurate predictions of incipient conditions of clathrate hydrates. Intermolecular repulsive force is the dominant force in cavity space that is a determinative factor in taking the guest–host interactions into account. As the result, further modifications in potential function part of van der Waals and Platteeuw (vdWP) solid solution theory could improve the model accuracy. In this study, the influence of repulsive force between guest–host molecules in hydrate cavities was investigated through replacing Kihara potential function by Exp-6 potential function. The vdWP model equations were derived based on new potential function. The pair potential parameters were regressed using equilibrium dissociation conditions data of simple hydrates of natural gas constituents. The determination performances of Kihara and Exp-6 potential functions were compared in aspects of incipient hydrate dissociation conditions and hydrate composition of binary hydrate formers and mixtures of natural gas systems. The results show a promising improvement in vdWP model in case of binary hydrate systems, while the accuracy of the model does not change dramatically in case of natural gas hydrate system. This is due to cancellation of changes in Gibbs energy of occupation for different guest species and the natural gas composition.

Assessing Sex, Gender Identity, Sexual Orientation, Race, Ethnicity, Socioeconomic Status, and Mental Health Concerns in Tobacco Use Disorder Treatment Research: Measurement Challenges and Recommendations From a Society for Research on Nicotine and Tobacco Pre-conference Workshop.

This paper reports on topics discussed at a Society for Research on Nicotine and Tobacco pre-conference workshop at the 2019 annual Society for Research on Nicotine and Tobacco meeting. The goal of the pre-conference workshop was to help develop a shared understanding of the importance of several tobacco-related priority groups in tobacco use disorder (TUD) treatment research and to highlight challenges in measurement related to these groups. The workshop focused on persons with minoritized sex, gender identity, and sexual orientation identities; persons with minoritized racial and ethnic backgrounds; persons with lower socioeconomic status (SES); and persons with mental health concerns. In addition to experiencing commercial tobacco-related health disparities, these groups are also underrepresented in tobacco research, including TUD treatment studies. Importantly, there is wide variation in how and whether researchers are identifying variation within these priority groups. Best practices for measuring and reporting sex, gender identity, sexual orientation, race, ethnicity, SES, and mental health concerns in TUD treatment research are needed. This paper provides information about measurement challenges when including these groups in TUD treatment research and specific recommendations about how to measure these groups and assess potential disparities in outcomes. The goal of this paper is to encourage TUD treatment researchers to use measurement best practices in these priority groups in an effort to conduct meaningful and equity-promoting research. Increasing the inclusion and visibility of these groups in TUD treatment research will help to move the field forward in decreasing tobacco-related health disparities. Implications: Tobacco-related disparities exist for a number of priority groups including, among others, women, individuals with minoritized sexual and gender identities, individuals with minoritized racial and ethnic backgrounds, individuals with lower SES, and individuals with mental health concerns. Research on TUD treatments for many of these subgroups is lacking. Accurate assessment and consideration of these subgroups will provide needed information about efficacious and effective TUD treatments, about potential mediators and moderators, and for accurately describing study samples, all critical elements for reducing tobacco-related disparities, and improving diversity, equity, and inclusion in TUD treatment research.

Effects of Constant versus Fluctuating Temperatures on Fitness Indicators of the Aphid Dysaphis plantaginea and the Parasitoid Aphidius matricariae.

Simple SummaryLike all organisms, insects encounter temperatures that fluctuate on different time scales: within a day, between days, or throughout the seasons. However, most studies on the impact of temperature on insect physiology, behavior, morphology, or ecology have focused on constant temperatures tested in the laboratory. In our study, we wanted to know if fluctuating temperatures during the day (7–17 °C, average 12 °C) can affect insects differently compared to a constant temperature of 12 °C. We used, as a model, the apple aphid Dysaphis plantaginea, a major threat to apple orchards worldwide, and its parasitoid Aphidius matricariae, which is used in biological control. We found that many traits—but not all—were affected. In particular, the fluctuating thermal regime reduced the development time of aphids and parasitoids, improved the rate of parasitism, and tended (albeit slightly) to increase the longevity of both species. In contrast, we did not find strong effects on morphological traits. Our results can be used to better predict how these agronomically important insects behave in orchards, how ecologically-relevant fluctuating temperatures affect host–parasitoid relationships, and ultimately what the implications are in the context of climate change and biological control.Testing fluctuating rather than constant temperatures is likely to produce more realistic datasets, as they are ecologically more similar to what arthropods experience in nature. In this study, we evaluated the impact of three constant thermal regimes (7, 12, and 17 °C) and one fluctuating thermal regime (7–17 °C with a mean of 12 °C) on fitness indicators in the rosy apple aphid Dysaphis plantaginea, a major pest of apple orchards, and the parasitoid Aphidius matricariae, one of its natural enemies used in mass release biological control strategies. For some—but not all—traits, the fluctuating 7–17 °C regime was beneficial to insects compared to the constant 12 °C regime. Both aphid and parasitoid development times were shortened under the fluctuating regime, and there was a clear trend towards an increased longevity under the fluctuating regime. The fecundity, mass, and size were affected by the mean temperature, but only the mass of aphids was higher at 7–17 °C than at a constant 12 °C. Parasitism rates, but not emergence rates, were higher under the fluctuating regime than under the constant 12 °C regime. Results are discussed within the framework of insect thermal ecology and Jensen’s inequality. We conclude that incorporating thermal fluctuations in ecological studies could allow for the more accurate consideration of how temperature affects host–parasitoid interactions and insect responses to temperature change over time.

Evaluation of Radar/Optical Based Vegetation Descriptors in Water Cloud Model for Soil Moisture Retrieval

The accurate consideration of vegetation descriptors in water cloud model (WCM) is necessary for precise SM retrieval. Most of the vegetation descriptors are sourced from optical remote sensors. The acquisitions from optical sensors are largely hampered by bad weather conditions. For all-weather monitoring, Synthetic Aperture Radar (SAR) based vegetation descriptors are needed to identify and evaluate their performance for SM retrieval. The present study evaluates the various sources/combinations of SAR based vegetation descriptors in WCM to identify the better alternatives of optical-based vegetation descriptors. The performance of three radar-based vegetation descriptors, namely VH polarized backscattering coefficients, depolarization ratio and radar vegetation index (RVI) along with the one optical-based vegetation descriptor, namely leaf area index (LAI) from MODIS were utilized in WCM. The WCM for each vegetation descriptor has been performed using Sentinel-1 VV polarized backscattering coefficients and in-situ SM. The in-situ SM measurements were carried out in the fields around Varanasi District in India during the winter season sown with the wheat crop. The correlations coefficient (r), root mean square error (RMSE) and bias were used to evaluate the performances of vegetation descriptors in WCM for SM retrieval. The study showed that the depolarization ratio is the best for SM retrieval with accuracy of 0.096 m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> followed by RVI, cross-polarized and LAI with 0.100 m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> , 0.124 m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> and 0.124 m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> , respectively. Thus, the depolarization ratio can be used for the retrieval of SM using Sentinel-1 VV polarized backscattering coefficients over the wheat crop.

A Review of Evapotranspiration Measurement Models, Techniques and Methods for Open and Closed Agricultural Field Applications

Detailed knowledge of energy and mass fluxes between land and the atmosphere are necessary to monitor the climate of the land and effectively exploit it in growing agricultural commodities. One of the important surface land fluxes is evapotranspiration, which combines the process of evaporation from the soil and that of transpiration from plants, describing the movement of water vapour from the land to the atmosphere. Accurately estimating evapotranspiration in agricultural systems is of high importance for efficient use of water resources and precise irrigation scheduling operations that will lead to improved water use efficiency. This paper reviews the major mechanistic and empirical models for estimating evapotranspiration including the Penman–Monteith, Stanghellini, Priestly–Taylor, and Hargreaves and Samani models. Moreover, the major differences between the models and their underlined assumptions are discussed. The application of these models is also reviewed for both open and closed field mediums and limitations of each model are highlighted. The main parameters affecting evapotranspiration rates in greenhouse settings including aerodynamic resistance, stomatal resistance and intercepted radiation are thoroughly discussed for accurate measurement and consideration in evapotranspiration models. Moreover, this review discusses direct evapotranspiration measurements systems such as eddy covariance and gas exchange systems. Other direct measurements appertaining to specific parameters such as leaf area index and surface leaf temperature and indirect measurements such as remote sensing are also presented, which can be integrated into evapotranspiration models for adaptation depending on climate and physiological characteristics of the growing medium. This review offers important directions for the estimation of evapotranspiration rates depending on the agricultural setting and the available climatological and physiological data, in addition to experimentally based adaptation processes for ET models. It also discusses how accurate evapotranspiration measurements can optimise the energy, water and food nexus.

On-off cycling model featured with pattern recognition of air-to-water heat pumps

The air-to-water heat pump (AWHP) works frequently under partial load and suffers frequent on–off cycles in practical application. The concomitant efficiency degradation can be up to 25%, while the existing simulation work of the AWHP heating system lacks full and accurate consideration of the cycling losses. Based on the field-trial data driving and verification, an artificial neural network (ANN) model featured with pattern recognition is established to simulate the on–off transient response of AWHP, by introducing two time stamps into the source data to distinguish the power consumption and the heating capacity are in whether the start-up stage or the steady state respectively, and then training ANNs severally with different datasets. The system model is further developed in combination with the heat balance among the building heating load, the terminal heat release rate and the AWHP heat supply rate. The Mean Absolute Percentage Error within the start-up stage and the overall period could be controlled no more than 11% and 6% respectively. This study provides a reliable platform for cycling losses analysis and control strategy optimization. A variable hysteresis control algorithm of supply water temperature was conducted. By enlarging the control dead band, the on–off cycles could be reduced by 75.2%, the system coefficient of performance could be raised from 1.82 to 2.09 (increased by 14.6%) and the system power consumption could be reduced from 80.5kWh/d to 60.2kWh/d (decreased by 18.9%).

Flexural buckling resistance of rectangular welded box section columns

AbstractApplication of high strength steel (HSS – S420 and higher steel grades) is growing nowadays in the civil engineering praxis due to the numerous advantages compared to the normal strength steel (NSS – S235‐S355). The accurate consideration of the flexural buckling resistance of HSS structures is highly important in the design. Higher yield strength indicates the applicability of smaller cross‐sections, which might be more sensitive for stability problems. The purpose of the current study is (1) to investigate the flexural buckling behaviour of HSS welded rectangular box section columns and (2) to propose a reliable column buckling curve.Residual stress in steel structural elements have significant influence on the flexural buckling behaviour of welded box section columns. This phenomenon causes that hot‐rolled, cold‐formed and welded sections have different flexural buckling behaviour and resistance. Previous research results of the authors proved that different buckling curves can be used for HSS or NSS welded square box section columns. Research is continued and extended to the investigation of rectangular box sections, which significantly increase the applicability of the design proposals. The buckling resistances for NSS and HSS rectangular welded box section columns are determined by using deterministic numerical simulation technique for a wide range of relative slenderness and steel grades. Based on the simulation results buckling curves are proposed for all the analysed steel grades and aspect ratios.

Fourier modal method for moiré lattices

In recent years twisted bi-layers of 2D materials became very popular in the field due to the possibility to totally change their electronic properties by simple rotation. At the same time, in the wide field of photonic crystals, this idea still remains almost untouched, and only some particular problems were considered. One of the reasons is the computational difficulty of the accurate consideration of Moir\'e superlattices that appear due to the superimposition of misaligned lattices. Indeed, the unit cell of the complex lattice is typically much larger than the original crystals and requires much more computational resources for the computations. Here, we propose a careful adaptation of the Fourier modal method in the form of the scattering matrices for the description of twisted 1D gratings' stacks. Our approach allows us to consider sublattices in close vicinity to each other and account for their interaction via the near-field. In the developed numerical scheme, we utilize the fact that each sublattice is only 1D-periodic and therefore simpler than the resulting 2D superlattice, as well as the fact that even a small gap between the lattices filters out high Fourier harmonics due to their evanescent origin. This accelerates the computations from 1 up to 3 and more orders of magnitude for typical structures depending on the number of harmonics. This paves the way for rigorous study of almost any photonic crystals of the proposed geometry and demonstration of specific Moir\'e-associated effects.

The effect of landscape and human settlement on the genetic differentiation and presence of Paragonimus species in Mesoamerica

Foodborne diseases are a neglected research area, and despite the existence of many tools for diagnosis and genetic studies, very little is known about the effect of the landscape on the genetic diversity and presence of parasites. One of these foodborne disease is paragonimiasis, caused by trematodes of the genus Paragonimus, which is responsible for a high number of infections in humans and wild animals. The main Paragonimus sp reported in Mesoamerica is Paragonimus mexicanus, yet there are doubts about its correct identification as a unique species throughout the region. This, together with a lack of detailed knowledge about their ecology, evolution and differentiation, may complicate the implementation of control strategies across the Mesoamerican region. We had the goal of delimiting the species of P. mexicanus found throughout Mesoamerica and determining the effect of landscape and geology on the diversity and presence of the parasite. We found support for the delimitation of five genetic groups. The genetic differentiation among these groups was positively affected by elevation and the isolation of river basins, while the parasite’s presence was affected negatively only by the presence of human settlements. These results suggest that areas with lower elevation, connected rivers basins, and an absence of human settlements have low genetic differentiation and high P. mexicanus presence, which may increase the risk of Paragonimus infection. These demonstrate the importance of accurate species delimitation and consideration of the effect of landscape on Paragonimus in the proposal of adequate control strategies. However, other landscape variables cannot be discarded, including temperature, rainfall regime, and spatial scale (local, landscape and regional). These additional variables were not explored here, and should be considered in future studies.

Modelling Exposure by Spraying Activities-Status and Future Needs.

Spray applications enable a uniform distribution of substances on surfaces in a highly efficient manner, and thus can be found at workplaces as well as in consumer environments. A systematic literature review on modelling exposure by spraying activities has been conducted and status and further needs have been discussed with experts at a symposium. This review summarizes the current knowledge about models and their level of conservatism and accuracy. We found that extraction of relevant information on model performance for spraying from published studies and interpretation of model accuracy proved to be challenging, as the studies often accounted for only a small part of potential spray applications. To achieve a better quality of exposure estimates in the future, more systematic evaluation of models is beneficial, taking into account a representative variety of spray equipment and application patterns. Model predictions could be improved by more accurate consideration of variation in spray equipment. Inter-model harmonization with regard to spray input parameters and appropriate grouping of spray exposure situations is recommended. From a user perspective, a platform or database with information on different spraying equipment and techniques and agreed standard parameters for specific spraying scenarios from different regulations may be useful.

The Medial Orbitofrontal Cortex–Basolateral Amygdala Circuit Regulates the Influence of Reward Cues on Adaptive Behavior and Choice

Adaptive reward-related decision making requires accurate prospective consideration of the specific outcome of each option and its current desirability. Often this information must be inferred based on the presence of predictive environmental events. The basolateral amygdala (BLA) and medial orbitofrontal cortex (mOFC) are two key nodes in the circuitry supporting such outcome expectations, but very little is known about the function of direct connections between these regions. Here, in male rats, we first anatomically confirmed the existence of bidirectional, direct projections between the mOFC and BLA and found that BLA projections to mOFC are largely distinct from those to lateral OFC (lOFC). Next, using pathway-specific chemogenetic inhibition and the outcome-selective Pavlovian-to-instrumental transfer and devaluation tests, we interrogated the function of the bidirectional mOFC-BLA connections in reward-directed behavior. We found evidence that the mOFC→BLA pathway mediates the use of environmental cues to understand which specific reward is predicted, information needed to infer which action to choose, and how desirable that reward is to ensure adaptive responses to the cue. By contrast, the BLA→mOFC pathway is not needed to use the identity of an expected reward to guide choice but does mediate adaptive responses to cues based on the current desirability of the reward they predict. These functions differ from those we previously identified for the lOFC-BLA circuit. Collectively, the data reveal the mOFC-BLA circuit as critical for the cue-dependent reward outcome expectations that influence adaptive behavior and decision making.SIGNIFICANCE STATEMENT To make good decisions we evaluate how advantageous a particular course of action would be. This requires understanding what rewarding outcomes can be expected and how desirable they currently are. Such prospective considerations are critical for adaptive decision making but disrupted in many psychiatric diseases. Here, we reveal that direct connections between the medial orbitofrontal cortex and basolateral amygdala mediate these functions. These findings are especially important in light of evidence of dysfunction in this circuit in substance use disorder and mental illnesses marked by poor decision making.

Conformational analysis of tannic acid: Environment effects in electronic and reactivity properties.

Polyphenols are natural molecules of crucial importance in many applications, of which tannic acid (TA) is one of the most abundant and established. Most high-value applications require precise control of TA interactions with the system of interest. However, the molecular structure of TA is still not comprehended at the atomic level, of which all electronic and reactivity properties depend. Here, we combine an enhanced sampling global optimization method with density functional theory (DFT)-based calculations to explore the conformational space of TA assisted by unsupervised machine learning visualization and then investigate its lowest energy conformers. We study the external environment's effect on the TA structure and properties. We find that vacuum favors compact structures by stabilizing peripheral atoms' weak interactions, while in water, the molecule adopts more open conformations. The frontier molecular orbitals of the conformers with the lowest harmonic vibrational free energy have a HOMO-LUMO energy gap of 2.21 (3.27) eV, increasing to 2.82 (3.88) eV in water, at the DFT generalized gradient approximation (and hybrid) level of theory. Structural differences also change the distribution of potential reactive sites. We establish the fundamental importance of accurate structural consideration in determining TA and related polyphenol interactions in relevant technological applications.

International marketing as an effective tool of increasing enterprise competitiveness

The main features of international marketing as a tool to increase the competitiveness of the enterprise are considered in the article.&#x0D; Crisis phenomena of today's economy, long reforms of national production, the formation of a new information society and the emergence of information processes in the economy have led to the fact that future economic growth becomes possible only if the introduction and coordination of modern marketing and management tools for fuller implementation of foreign economic relations of the state, accurate consideration of production needs for domestic and foreign sales, coordination of export opportunities and import needs, providing for the production of competitive products, strengthening the impact on the international division of labor, international specialization and internationalization of production and, consequently, improving foreign economic activity .&#x0D; Thus, the development of marketing of international production and the movement of entrepreneurial capital cause uneven growth of economic potential of individual countries and regions. The transfer of production to certain countries leads to the fact that the shares of different groups of countries in the location of world industry do not coincide. Competition between TNCs distorts the system of international relations between the world economy.&#x0D; International marketing of exports and imports are two barter transactions, through which each country is organically connected with the external environment. These are components of the reproduction process, which must pass through foreign trade in order to ensure the stable creation, distribution and consumption of national GDP. The effect of international marketing of barter transactions or another country can get based on the scale of production. Foreign trade may not necessarily be mutually beneficial for all actors in the world market. Reproductive openness of the country when using international marketing depends on the availability of natural resources in the country - energy resources, raw materials for industry, food for the population. The level of reproductive openness of the state is higher, the higher the level of its technical and economic development and the smaller the value of its GDP and the availability of its own natural resources.

Benefits of the Adaptive Algorithm for Retracking Altimeter Nadir Echoes: Results From Simulations and CFOSAT/SWIM Observations

The accuracy of sea surface parameters retrieved from altimeter missions is predominantly governed by the choice of the so-called “retracking” algorithm, i.e., the model and inversion method implemented to obtain the surface parameters from the backscattered waveform. For continuity reasons, the choice of space agencies is usually to apply the same retracker from one satellite mission to the other to ensure long-time homogeneous series. In this article, taking the opportunity of a new configuration of the nadir pointing measurements onboard the recently launched China France Oceanography Satellite (CFOSAT) with the Surface Waves Investigation and Monitoring (SWIM) instrument (Hauser <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">et al.,</i> 2020), the retracking method was upgraded, by implementing a novel algorithm, called “Adaptive” retracker. It combines the improvements brought by Poisson <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">et al.,</i> (2018) for the estimation of surface parameters from peaked waveforms over sea ice, improvements in the way the instrumental characteristics are considered in the model (mispointing, point target response) and a more accurate consideration of speckle statistics. In this article, we first show from simulations carried out in the instrumental configuration of SWIM that the Adaptive algorithm has better accuracy and performance than the classical MLE4 algorithm. Then, the geophysical parameters obtained with real data from SWIM are analyzed with comparisons to reference data sets (model and products from altimeters). We show that this new algorithm has several benefits with respect to the classical MLE4 method: no need of lookup tables to correct biases, significant noise reduction on all geophysical variables especially the significant wave height, and performance of inversion over a large set of echo shapes, resulting from standard oceanic scenes as well as highly specular conditions such as over bloom or sea ice.

Environmental lumping for efficient fatigue assessment of large-diameter monopile wind turbines

Fatigue damage is one of the governing factors for the design of offshore wind turbines. However, the full fatigue assessment is a time-consuming task. During the design process, the site-specific environmental parameters are usually condensed by a lumping process to reduce the computational effort. Preservation of fatigue damage during lumping requires an accurate consideration of the met-ocean climate and the dynamic response of the structure. Two lumping methods (time-domain and frequency-domain) have been evaluated for a monopile-based 10 MW offshore wind turbine, both based on damage-equivalent contour lines. Fatigue damage from lumped load cases was compared to full long-term fatigue assessment. The lumping methods had an accuracy of 94–98% for the total long-term fatigue damage and 90% for individual wind speed classes, for aligned wind and waves. Fatigue damage was preserved with the same accuracy levels for the whole support structure. A significant reduction of computational time (93%) was achieved compared to a full long-term fatigue assessment. For the cases with 30° and 60° wind-wave misalignment, there was a mean underestimation of approximately 10%. Variations in penetration depth did not affect the selection of the lumped sea-state parameters. This work presents a straightforward method for the selection of damage-equivalent lumped load cases, which can adequately preserve long-term fatigue damage throughout the support structure, providing considerable reduction of computational effort.

Coherent 2D electronic spectroscopy with complete characterization of excitation pulses during all scanning steps.

Coherent two-dimensional (2D) electronic spectroscopy has become a standard tool in ultrafast science. Thus it is relevant to consider the accuracy of data considering both experimental imperfections and theoretical assumptions about idealized conditions. It is already known that chirped excitation pulses can affect 2D line shapes. In the present work, we demonstrate performance-efficient, automated characterization of the full electric field of each individual multipulse sequence employed during a 2D scanning procedure. Using Fourier-transform spectral interferometry, we analyze how the temporal intensity and phase profile varies from scanning step to scanning step and extract relevant pulse-sequence parameters. This takes into account both random and systematic variations during the scan that may be caused, for example, by femtosecond pulse-shaping artifacts. Using the characterized fields, we simulate and compare 2D spectra obtained with idealized and real shapes obtained from an LCD-based pulse shaper. Exemplarily, we consider fluorescence of a molecular dimer and multiphoton photoemission of a plasmonic nanoslit. The deviations from pulse-shaper artifacts in our specific case do not distort strongly the population-based multidimensional data. The characterization procedure is applicable to other pulses-shaping technologies or excitation geometries, including also pump-probe geometry with multipulse excitation and coherent detection, and allows for accurate consideration of realistic optical excitation fields at all inter-pulse time-delays.