Time Shift Research Articles

A Six-Year (2014–2020) Statistical Correlation Study of VLF Terminator Time Shift with Earthquakes in Japan

In this study, we present a six-year (2014–2020) statistical analysis of VLF subionospheric propagation data at 19 VLF receivers from the VLF transmitter with call name JJI and frequency 22.2 kHz, all located in Japan. Moderate and strong earthquakes (EQs) (ML≥4.5 and depth ≤ 50 km) that occurred in the wider area around Japan during the same time period with the available VLF data are investigated. The terminator times’ (TT) shift in VLF amplitude data as a possible precursor of an EQ are statistically examined, focusing on the correlation with seismic activity. The concept of the effective EQ magnitude (Meff) is used in order to define the total EQ energy possibly affecting the midpoint of each path for each day. It is important to note that dates when geomagnetic storms or solar flares occurred as well as dates corresponding to the already known winter effect on TT statistics in the north–south direction were excluded. The cross-correlation between TT statistical anomalies and seismic activity, represented by Meff, was extracted. Maximum cross-correlation values were found for most of the cases prior to the subsequent seismic activity, indicating a link between the ionospheric anomalies and the subsequent seismicity. Finally, the wide temporal range of the cross-correlation maxima temporal locations is justified by the inhomogeneity of the lower ionosphere, coupled with the anisotropy of the preseismic effect of the impending seismicity, highlighting the complexity of the EQ preparation processes.

Increase of Reliability of Anomalies Detection on Images at Formation of Their Feature Vectors in Wavelet Bases

The method of detection of life rafts and lifeboats in the water area of seas and oceans after shipwrecks based on the recognition of anomalies in the processed images, which increases the probability of recognition of monitoring objects, is proposed. The approach to solving such a problem is substantiated. The formulation of the problem of object recognition from the perspective of binary classification in the detection of anomalies is presented. The analytical expression for the decision-making algorithm is obtained. The possibility of formalization of image matrices in the form of histograms of color (brightness) intensity distributions is considered. The contrast of the feature space on their basis is estimated. It is suggested that the contrast of feature spaces be increased due to the secondary processing of histograms of distributions in the basis of multiple-scale wavelet decomposition. The possibility of realization of wavelet transformations on the basis of Haar functions and Gauss wavelets of the 1st and 2nd orders is considered. The mechanism of formation of secondary feature vectors from three-dimensional wavelet transforms by averaging their coefficients along the time shift axis is substantiated. It is shown that at the same dimensionality of histograms of brightness distribution with newly formed feature vectors, the latter provide higher contrast of feature spaces. It is recommended to use a Gaussian wavelet of the 2nd order for the formalization of images in jpeg format, which provides, other things being equal, a greater magnitude of differences for images containing anomalies. An approach to probabilistic evaluation of the algorithm for automatic image recognition is developed. The analytical expression is obtained and its constituent elements are justified. Graphical dependences of the probability of correct detection (recognition) of anomalies, depending on the size in relation to the total area of the frame and the dispersion of the underlying background are given. The results of the experiment on image recognition with a lifeboat in the ocean water area are presented. The directions of further research are defined.

Detection of Traffic Anomalies Based on Their Frame Wavelet Transformations Processing

Relevance. The active transition to a massive digital infrastructure based on Internet of Things (IoT) technology has brought telecommunications networks to the level of dominant information resources. The one-time increase in the number of existing Internet services is inextricably linked to the growing variety of network anomalies on telecommunications equipment. In turn, existing methods of detecting network threats do not allow timely assessment of network traffic, which is characterized by a large number of parameters, and the detected anomalies from external interference do not have pronounced patterns. The purpose of the study is to increase the efficiency of detecting traffic anomalies based on the results of processing its frame wavelet transform. The scientific task is to develop scientific and methodological approaches that allow effective analysis and timely detection of anomalies in network traffic. A comparative review of search methods for detecting network traffic anomalies, algorithms for detecting uncontrolled anomalies, traffic analysis methods based on local emission factor, binary trees, optical emission spectroscopy. Decision. The results of the study of the possibility of detecting anomalies in the bitstream traffic based on the results of its multiple-variable transformation in the Haar wavelet basis are considered. The choice for further processing of the coefficients of the traffic decomposition matrix along the time shift variable is justified. It is proved that multiple-scale transformations not only increase the structural differences in traffic, but also open up the possibility of localization of anomalies that caused these differences. The scientific novelty of the work is determined by the author's approach to detecting network traffic anomalies during the transition from the direct representation of a signal in the form of its discrete samples to coefficients formed from the matrices of its wavelet transformations, and, as a result, increasing its contrast with other signals with a similar structure. Theoretical significance. The necessity and sufficiency of using wavelet coefficients instead of time samples of signals in the basis of the parent wavelet from the matrix of the generated frame is proved. The relationship between the Hurst indicators and the coefficients of the cross-correlation functions has been established. Practical significance. The results obtained in the work, in the future, can be used in the construction of models for evaluating network traffic in conditions of deliberate, as well as methods for searching and synthesizing effective methods of protection against them.

Global Dynamics of Bird Migration: Trends, Mechanisms and Conservation Challenges

Global bird migration is a complex phenomenon influenced by a multitude of factors, including climate change, habitat loss, and human activities. This paper explores the trends in migratory patterns observed over recent decades, highlighting shifts in timing, routes, and species distributions Bird migrations are behavioural occurrences, exemplifying intricate spatiotemporal tactics to optimise living expenses while enhancing fitness. Birds express a range of migratory patterns, from highly predictable obligate migration, to less predictable nomadic and fugitive migrations. Despite significant advancements in bird migration studies, still certain essential gaps remain. Due to technological advancement, bird migration studies have uncovered significant insights into the behavioural, cognitive, physiological, and evolutionary underpinnings. The seasonal variability of bird populations presents an intriguing phenomenon for avid observers to discern their origins, migratory routes, and return patterns. Among the remarkable migrations executed by several species of fish, animals, and insects, birds exemplify the highest degree of mobility among all living forms on Earth. This paper gives reasons for all Bird migration strategies with a view toward the preservation of Bird ecosystems and assurance of Environmental sustainability.

АНАЛИЗ ПРОИЗВОДИТЕЛЬНОСТИ ХМЕЛЕСУШИЛКИ С ЧАСТИЧНОЙ РЕКУПЕРАЦИЕЙ ТЕПЛОВОЙ ЭНЕРГИИ

Drying is an integral part of the technological process of commercial hop production. Depending on the production volume and the level of automation of the process, there are several ways to dry hop cones, including convective, microwave and sublimation. At the same time, dryers have different ratios of quality and productivity. Reducing energy costs for drying hops is an important area in the development of hop growing. In this regard, modernization and analysis of the productivity of hop dryers is a pressing issue in the current conditions of rising production costs. The aim of the research is to analyze the productivity of the MXS-25 hop dryer, modernized by installing a heat pump in the air circulation circuit and having adjustable heat recovery. The air temperature in the drying chamber was successfully controlled in the range of 60 ± 2 ° C. The preheating time required to achieve the air temperature was approximately 0.5 hours, which corresponds to approximately 5% of the total hop drying time. Comparison of the measured and calculated energy consumption values showed that the experimental values were in the range of 10.2 kWh to 11.5 kWh, averaging approximately 10.85 kWh during the experiment. Accordingly, the calculated values were in the range of 8.9 kWh and 10.2 kWh, averaging 9.55 kWh. A series of experiments comparing the drying performance using partial recovery showed that with an increase in the ambient temperature to 24 °C, the maximum relative moisture separation rate reached 6.23 kg/(kWh) with a bypass ratio of 0.86, which was higher than that of 5.54 kg/(kWh) for drying with full recovery. The partial heat recovery system is superior to the full recovery system in terms of energy efficiency and increased hop drying performance.

Efficiency of infrared pyrometer and infrared thermography for assessing body surface temperature in hair sheep

The objectives of this study were: (i) to verify and compare the coat surface temperature (CST) of regions of interest (ROI) measured through infrared pyrometer (IRP) and thermography (IRT) under two environmental conditions, to evaluate (ii) reliability and (iii) sensitivity of the two infrared equipments to the environmental effect. Twenty hair ewes (Ovis aries), multiparous, non-lactating, non-pregnant, with body weight 59.38 ± 6.23 kg and body score condition ranging from 2.5 to 4.5 were evaluated. All CST, in both infrared methods, were higher (P < 0.001) in the afternoon (2 to 3 p.m.), with the exception of eyes surface temperature (TSEY) from IRT, which was higher (P < 0.001) in the morning (8 to 9 a.m.). Regarding the infrared methods at different times (twice a day, morning and afternoon), of the day, CST values for all ROIs were significantly higher (P < 0.001) in thermography, regardless of the time shift, except for ear pinna surface temperature (TSE) and rectum surface temperature (TSR), which showed no significant difference (P > 0.05) between the infrared methods during the morning shift. The thermal environment significantly influences (P < 0.001) the surface temperature of various anatomical regions in both infrared methods. The correlation coefficients between IRT and IRP were moderate. The IRT is more sensitive to the thermal environment, as it presented higher canonical coefficients in the environmental variables. Among surface temperatures, eye surface temperature is the most influenced by variables in the thermal environment, especially THI. All three methods (digital thermometer-DT, IRT and IRP) showed >80 % of the data variation in the first two components. Using the DT, we observed an association between vaginal temperature (VT) and RT with air temperature (AT) and temperature humidity index (THI), which was similar to the infrared thermography pattern, in which all ROIs were highly correlated with AT and THI. The opposite was observed in the pyrometer, in which an association between eye temperature and RH and lower factor loadings of the other ROIs with AT and THI in the first component was observed. In conclusion, while IRP and IRT showed similar performance in the morning, IRT proved to be more accurate in the afternoon, demonstrating a higher success rate in classifying the group of origin. Therefore, it is concluded that IRT is more reliable than IRP in detecting surface temperature changes under high temperatures.

Supervised Deep Learning for Detecting and Locating Passive Seismic Events Recorded with DAS: A Case Study

Exploring shallow mineral resources requires acquiring denser seismic data, for which Distributed Acoustic Sensing is an effective enabler and relevant to mining operations monitoring. Passive seismic can be of interest in characterizing the subsurface; however, dealing with large amounts of data pushes against the limits of existing computational systems and algorithms, especially for continuous monitoring. Hence, more than ever, novel data analysis methods are needed. In this article, we investigate using synthetic seismic data, paired with real noise recordings, as part of a supervised deep-learning neural network methodology to detect and locate induced seismic sources and explore their potential use to reconstruct subsurface properties. Challenges of this methodology were identified and addressed in the context of induced seismicity applications. Data acquisition and modelling were discussed, preparation workflows were implemented, and the method was demonstrated on synthetic data and tested on relevant seismic monitoring field dataset from the Otway CO2 injection site. Conducted tests confirmed the effects of time shifts, signal-to-noise ratios, and geometry mismatches on the performance of trained models. Those promising results showed the method’s applicability and paved the way for potential application to more field data, such as seismic while drilling.

Orexinergic modulation of chronic jet lag-induced deficits in mouse cognitive flexibility.

Cognitive flexibility and working memory are important executive functions mediated by the prefrontal cortex and can be impaired by circadian rhythm disturbances such as chronic jet lag (CJL) or shift work. In the present study, we used mice to investigate whether (1) simulated CJL impairs cognitive flexibility, (2) the orexin system is involved in such impairment, and (3) nasal administration of orexin A is able to reverse CJL-induced deficits in cognitive flexibility and working memory. Mice were exposed to either standard light-dark conditions or simulated CJL consisting of series of advance time shifts. Experiment (1) investigated the effects of a mild CJL protocol on cognitive flexibility using the attentional set shifting task. Experiment (2) used a stronger CJL protocol and examined CJL effects on the orexin system utilizing c-Fos and orexin immunohistochemistry. Experiment (3) tested whether nasal orexin application can rescue CJL-induced deficits in cognitive flexibility and working memory, the latter by measuring spontaneous alternation in the Y-maze. The present data show that CJL (1) impairs cognitive flexibility and (2) reduces the activity of orexin neurons in the lateral hypothalamus. (3) Nasal administration of orexin A rescued CJL-induced deficits in working memory and cognitive flexibility. These findings suggest that executive function impairments by circadian rhythm disturbances such as CJL are caused by dysregulation of orexinergic input to the prefrontal cortex. Compensation of decreased orexinergic input by nasal administration of orexin A could be a potential therapy for CJL- or shift work-induced human deficits in executive functions.

Optimizing crop monitoring: mapping cultivation stages and types with sentinel-1/2 and random forest algorithm

ABSTRACT Crop-type mapping is essential for agricultural monitoring, improving crop yield models, and supporting sustainable land management. Studying crop phenology, which includes the timing from germination to maturity, is equally important for precise agricultural practices. However, maps detailing crop phenology are scarce. This study addresses this gap by mapping both crop types and cultivation time, offering valuable insights for agriculture applications. The research integrates Sentinel-1/2 data, NDVI phenology curves, and machine learning (ML) algorithms through Google Earth Engine to map crops in El-Behera Governorate, Egypt. By stratifying the region into different soil types, it accounts for various agro-environmental conditions. Field visits in July 2022 provided crop-type information, and Sentinel-2 NDVI curves were used to determine cultivation time. The random forest (RF) classifier, known for its accuracy, was employed, achieving an overall accuracy (OA) of 97.4% for crop type and 95.6% for cultivation time, with high Kappa coefficients. Feature importance analysis highlighted the significance of specific spectral bands, particularly in the Red Edge region, for classification accuracy. Hyperparameter tuning across different zones demonstrated the need for customized tuning. This study enhances understanding of agro-environmental variability’s impact on crop classification and shows the potential of the RF algorithm in advancing crop mapping, suggesting further studies on how shifts in cultivation time could affect crop yield.

A review of climate change impacts on migration patterns of marine vertebrates in Arctic and Subarctic ecosystems

Climate change is impacting marine ecosystems throughout the circumpolar Arctic, altering seasonal habitats and the food bases for fishes, seabirds, and marine mammals. Arctic and Subarctic regions provide resources for resident species and for species that migrate to the north from more southerly regions. Changes in northerly latitudes thus impact endemic as well as non-endemic animals. Herein, we review what is known about climate-driven changes in the migration patterns of Arctic and Subarctic marine vertebrates, including: 1) Arctic residents with seasonal movements – those fishes, seabirds, and marine mammals that complete their entire life cycle within the Arctic but exhibit seasonal movements; 2) Breeding migrants – many seabirds enter the Arctic to breed and subsequently migrate south in the fall; and 3) Summer visitors for feeding – certain species of boreal fishes, seabirds and marine mammals arrive during the northern summer to feed on abundant prey though they breed elsewhere. Migratory movements are often driven by the timing and extent of sea ice, which defines suitable habitat for some animals and limits access to open water and prey for others. Longer open-water seasons, warmer ocean temperatures, and stronger winds have resulted in earlier production blooms in spring and often, extended open-ocean plankton blooms into late summer, resulting in altered prey types and distributions. A common thread among taxa is that shifts in distribution and timing of migrating animals indicate they are traveling farther north, or shifting longitudinally, and migrations are occurring over longer seasonal time frames. Species performing multiple lifetime migrations or long-distance migrants may need to adjust migration timing or routing iteratively to match changes in marine productivity. Altered animal distributions or phenology, and reduced sea ice, affects access to animals that are critical nutritional, economical, and cultural components of Indigenous people’s lives in the Arctic. Ongoing changes challenge the resilience and adaptability of Arctic people and ecosystems, and will require adaptive research and management approaches.

Rapid QC-MS: Interactive Dashboard for Synchronous Mass Spectrometry Data Acquisition Quality Control.

Consistently collecting high-quality liquid chromatography-coupled tandem mass spectrometry (LC-MS/MS) data is a time-consuming hurdle for untargeted workflows. Analytical controls such as internal and biological standards are commonly included in high-throughput workflows, helping researchers recognize low-integrity specimens regardless of their biological source. However, evaluating these standards as data are collected has remained a considerable bottleneck─in both person-hours and accuracy. Here we present Rapid QC-MS, an automated, interactive dashboard for assessing LC-MS/MS data quality. Minutes after a new data file is written, a browser-viewable dashboard is updated with quality control results spanning multiple performance dimensions such as instrument sensitivity, in-run retention time shifts, and mass accuracy drift. Rapid QC-MS provides interactive visualizations that help users recognize acute deviations in these performance metrics, as well as gradual drifts over periods of hours, days, months, or years. Rapid QC-MS is open-source, simple to install, and highly configurable. By integrating open-source Python libraries and widely used MS analysis software, it can adapt to any LC-MS/MS workflow. Rapid QC-MS runs locally and offers optional remote quality control by syncing with Google Drive. Furthermore, Rapid QC-MS can operate in a semiautonomous fashion, alerting users to specimens with potentially poor analytical integrity via frequently used messaging applications. Initially developed for integration with Thermo Orbitrap workflows, Rapid QC-MS offers a fast, straightforward approach to help users collect high-quality untargeted LC-MS/MS data by eliminating many of the most time-consuming steps in manual data curation. Download for free: https://github.com/czbiohub-sf/Rapid-QC-MS.

A GPU Algorithm for Solving the Positions of New Pulsars

Timing newly discovered pulsars requires gradually building up a timing model that connects observations taken days to months apart. This sometimes can be challenging when our initial knowledge of the pulsar’s position is arcminutes off from its true position. Such a position error leads to significant arrival time shifts as a result of the Earth’s orbital motion. Traditional down-hill fitting timing algorithms become ineffective when our model predicts the wrong pulse rotations for our next observation. For some pulsars whose model prediction is not too far off, the correct rotation number could be found by trial-and-error methods. For the remaining challenging pulsars, a more generalized method is called for. This paper proposes a GPU-based algorithm that could exhaustively search a large area of trail positions for probable timing solutions. This could help find phase-connected timing solutions for new pulsars using brute force.

Rapidly Screening the Correlation between the Rotational Mobility and the Hydrogen Bonding Strength of Confined Water.

Automated Deuterium Relaxation-Ordered SpectroscopY in solution (ADROSYS), an automated two-dimensional deuterium NMR methodology, discriminates between D2O populations (as well as deuterium-labeled alcohol groups) whose properties differ as a result of being confined inside nanoscale volumes. In this contribution, a proof-of-principle demonstration on reverse micelles (RMs) yields the insight that as the length scale of the confinement decreases from several nanometers down to less than a nanometer, the position of the signal peak migrates through the two-dimensional (2D) spectrum, tracing out a distinctive path in the 2D space (of relaxation time vs chemical shift). The signals typically follow a relatively gentle linear path for water confined on the scale of several nanometers, before curving once the surfactants confine the water molecules to length scales smaller than 1-2 nm. The qualitative shape of this path, especially in the regime of strong confinement, can change with different choices of surfactants, i.e., a different choice of chemistry at the edges of the confining environment. An important facet of this research was to demonstrate the relatively wide applicability of these techniques by showing that both: (1) Standard modern NMR instrumentation is capable of deploying an automated measurement, even though the choice of a deuterium nucleus is nonstandard and frequently requires companion proton spectra in order to reference the chemical shifts; and (2) well-established (though underutilized) modern techniques can process the resulting signal even though it involves the somewhat unusual combination of chemical shifts along one dimension and a distribution of relaxation times along another dimension. In addition to demonstrating that this technique can be deployed across many samples of interest, detailed facts pertaining to the broadening or shifting of resulting signals upon inclusion of various guest molecules are also discussed.

Effects and phenotypic consequences of transient thyrotoxicosis and hypothyroidism at different stages of zebrafish Danio rerio (Teleostei; Cyprinidae) skeleton development.

The effects and consequences of changes in thyroid hormones (THs) level are among the actively studied topics in teleost developmental and evolutionary biology. In most of the experimental models used, the altered hormonal status (either hypo- or hyperthyroidism) is a stable characteristic of the developing organism, and the observed phenotypic outcomes are the cumulative consequences of multiple TH-induced developmental changes. Meanwhile, the influence of the transient fluctuations of TH content on skeleton development has been much less studied. Here, we present experimental data on the developmental effects and phenotypic consequences of transient, pharmacologically induced thyrotoxicosis and hypothyroidism at different stages of ossified skeleton patterning in zebrafish. According to the results, the skeleton structures differed in TH sensitivity. Some showed a notable shift in the developmental timing and rate, while other demonstrated little or no response to changes in TH content. The developmental stages also differed in TH sensitivity. We identified a relatively short developmental period, during which changes in TH level significantly increased the developmental instability and plasticity, leading to phenotypic consequences comparable to those in fish with a persistent hypo- or hyperthyroidism. These findings allow this period to be considered as a critical developmental window.

FWI-WF: Robust full-waveform inversion using hybrid Wasserstein-1 and Fourier metrics

The performance of full-waveform inversion (FWI) in constructing high-resolution subsurface models is closely related to the design of mismatch functions. The least-squares norm ([Formula: see text]) is commonly used; however, it is prone to local minima when high-quality initial guess and low-frequency data are unavailable. The Wasserstein-1 ([Formula: see text]) metric captures time shifts more effectively, but it may be plagued by imprecise deep structures. The Fourier metric leverages power spectra from simulated and observed data, offering higher-resolution updates near solutions. We develop a progressive waveform inversion method called FWI-WF using [Formula: see text] and Fourier metrics. Specifically, in the early stage of inversion, we apply greater weight to the [Formula: see text] metric for constructing a good background model and avoiding falling into local minima. Then, the Fourier metric gradually dominates to refine edges and deep structures, providing high-resolution inversion results. During the optimization process, we use automatic differentiation to improve inversion efficiency. Experimental results on three baseline geologic models indicate that FWI-WF outperforms three state-of-the-art methods.

Hatch timing of largemouth bass: implications for recruitment at the Northern edge of their native range

Climate-related shifts in hatch timing could mean that age-0 largemouth bass Micropterus salmoides in north temperate lakes reach larger sizes and experience higher survival, which may contribute to increased prevalence of this species in many lakes. However, information on age-0 largemouth bass life history is lacking for these lakes. We estimated hatch dates, daily growth rates (DGR), and length-based probability of piscivory of age-0 largemouth bass in Wisconsin lakes to: (1) provide baseline data on early life history; (2) compare hatch timing between years with different spring temperature regimes, and (3) project how shifts in hatch timing might influence total length (TL) distributions of age-0 bass if mean DGR remained constant. Most age-0 largemouth bass (>90%) collected from ten Wisconsin lakes (N = 746) hatched between 23 May and 24 June during 2012 and 2013 and did not switch to piscivory during their first summer. Prevalence of positive correlations (16 of 24 lake-year pairings) between TL in and age indicates hatch timing may influence TLs attained by age-0 largemouth bass in August in some lake-years. Mean daily water temperatures in May 2012 were 3.1 °C warmer than in May 2013 for the five of the six lakes where hatch dates were estimated in both years. On average, earliest and median hatch dates for age-0 largemouth bass in these six lakes were 10–11 d earlier in 2012 than in 2013 and hatch duration was approximately 8 d longer in 2012. Despite differences in hatch timing, mean DGR was relatively consistent (range = 0.61–0.74 mm/d) between lakes and years. Simple simulations suggest that earlier hatch dates could result in more age-0 largemouth bass reaching TLs associated with piscivory and overwinter survival by the end of their first summer if growth rates did not change, which could translate to higher recruitment.

Phenological response of plants of different biomorphs to climate change in Western Siberia

The results of a phenology study of 78 species of perennial plants from biomorphological groups of chamaephytes, hemicryptophytes and geophytes over a 20-year period (1996—2015) are discussed. Against the background of air temperature and precipitation changes of the warm season in Novosibirsk, the timing shift in phenological events have been analyzed using calculated linear trends. It is found that the trends for species groups are multidirectional and vary significantly in magnitude. At the same time, most of the shifts in phenology are due not to trends, but to the interannual variability of climatic indicators.

Combining capillary electrophoresis and chemometric tools for the straightforward determination of imidazolinone herbicides in plant-based milks.

Highly polar herbicides, such as imidazolinones, are used for weed control to increase agricultural productivity and crop quality. However, their misapplication can lead to residues in ready-to-eat food with a potential health risk for consumers. Hence, the fast determination of these herbicides is necessary for timely action. In this work, an eco-friendly method based on capillary zone electrophoresis combined with chemometrics was used for the determination of imazapyr and imazamox in vegetable-based beverages such as soy and quinoa milk. The analytical strategy consisted of only three steps: (i) protein precipitation prior to sample injection (ii) data pre-processing to reduce the background and make corrections on electrophoretic times shift, and (iii) resolution of fully overlapped capillary electrophoresis (CE) peaks by the well-known partial least square (PLS) algorithm, which extracts quantitative information attributed to the analytes. The method was successfully applied in the concentration range between 1.00 and 100 μg L-1 with coefficient of determination of the calibration (R2 cal) and prediction (R2 pred) > 0.90, residual prediction deviation of calibration (RPDcal) and of prediction (RPDpred) > 3, and relative error of prediction (REP) > 11 in the analyzed sample matrices, in the three built methods (quinoa samples, soy samples, and joint quinoa and soy samples). The proposed methodology offers a simple and quick alternative for determining imidazolinones at trace concentrations in vegetable beverages, such as quinoa and soy milk, without complex sample preparation. The results were consistent with those obtained using more complex techniques, confirming the applicability of this method. © 2024 Society of Chemical Industry.

Coupling adaptive filters with acoustic travel time tomography for indoor climate measurements in occupied room conditions

Acoustic travel time TOMography (ATOM) as a remote sensing technique allows for the measurement of indoor climate parameters, such as air temperature and airflow velocity distributions. The performance of ATOM in monitoring indoor air temperature in empty room conditions was evaluated recently, utilizing a combined analysis approach of room acoustics and tomography. This study shifts focus to the assessment of ATOM in an occupied room condition where fixed objects are introduced to the test area. The presence of objects in a room can result in notable shifts in the travel times of individual reflections. In some cases, these shifts can cause reflections to disappear completely or be replaced by new ones. These partial disruptions in the reflection pattern present challenges in obtaining accurate information about the room's temperature. To ensure the accurate identification of undisturbed reflection paths, an algorithm was developed that can convert distorted signals into a pure reference signal using a suitable adaptive filter. The measurement results confirm the validity of the approach for a temperature interval of 4°C where the system was trained for two temperatures of 20°C and 24°C in a climate chamber.

Characterization of the scattered pressure from a cylindrical shell close to a free surface and understanding of the depth-dependent phenomenon

The characterization of the scattered pressure field of a submerged cylindrical target is of interest for underwater acoustics applications. The aim of this work is to study the vibroacoustic behavior of an immersed cylindrical shell excited by a plane wave, particularly in close proximity to a free surface. To achieve this goad, finite element simulation and experimental investigation are carried out on a mock-up. The effect of the free surface is highlighted by comparing results to those obtained in a free field situation, in both time and frequency domains. Additional echoes are observed on the time signals due to the presence of the free surface. In fact, after being scattered by the target, these echoes reflect on the surface, implying a time shift between echoes directly from the target and those that have travelled a longer path. The spectrum is also impacted as the form function shows additional oscillations. These observations are depth-dependent. To determine wave trajectories, a study based on flight time and ray theory is conducted.