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The objective of this study is to evaluate the ability of inverse techniques to estimate the resistance and the capacity of a highly insulated multilayer wall under real weather conditions. The wall is equipped with temperature sensors inside and on its inner and outer surfaces, and the boundary conditions have been measured over a 14-day period. Uncertainties on various parameters of the model are evaluated, including internal and external convective heat transfer coefficients (±20% and ±7 W.m-².K−1 respectively), external long-wave heat transfer coefficient (±0.15 W.m−2.K−1) and solar absorption coefficient (±0.06). A sensitivity analysis demonstrated the high correlation with some parameters defining the thermal performance of the walls (thermal resistance or capacity). A solution is proposed to limit the number of identified parameters, while allowing the identification of the thermal resistance and the thermal capacity of the walls. There are two cases: either the weather conditions are accurately measured (temperature, short- and long-wave radiation) and the thermal characteristics can be assessed, or intrusive sensors are installed, and the thermal characteristics can be evaluated more accurately. [ABSTRACT FROM AUTHOR]

Loads exerted to the seabed by short-crested wind-seas with a wide directional spread have extensive spatio-temporal variability. We quantify this variability in terms of near-bed water speed using an array of nine high-resolution hydromast devices for recording pressure and water velocity in the range of 0.12â1 m/s mounted at a distance of 10 m from each other on a rigid rectangular frame of 20 Ã 20 m in approximately 4 m deep water and 700 m from the eastern shore of the Gulf of Riga near Skulte (Latvia) in AugustâSeptember 2022. This array is complemented by an acoustic Doppler velocimeter (ADV). The average background current is very weak, approximately 0.003 m/s in the measurement location. The empirical distributions of velocity components are symmetric but greatly deviate from the expected Gaussian distribution. The empirical distributions of water speeds follow an exponential distribution rather than a Rayleigh or Forristall distribution. This shape of the distributions appears in the range of 0.2â0.7 m/s while the maximum speed reaches 1.22 m/s. The rate parameter (inverse scale parameter) varies almost by a factor of two in recordings by different devices. The recordings make it possible to identify wakes of vessels entering to or departing from the Port of Skulte.

Shock-induced vibrations transmitted from the racket to the tennis player’s upper limb have interested researchers, whether for investigating their effect on injury risk, or for designing new equipment. Measuring these vibrations is, however, very challenging in an ecological playing situation: sensors must be of very high quality in order to precisely measure high-energy and broad-frequency signals, as well as non-invasive in order to allow the players to perform their usual movements. The working hypothesis of this paper is that contactless sound recordings of the ball/racket impact carry the same information as direct vibratory measurements. The present study focuses on the tennis serve, as being tennis’ most energy-demanding stroke, therefore possibly being the most traumatic stroke for the upper limb. This article aims (a) to evaluate the propagation of vibration from the racket to the upper limb; and (b) to identify correlations with acoustic signals collected simultaneously. Eight expert tennis players performed serves with three rackets and two ball spin effects. Accelerometers measured the vibration on the racket and at five locations on the upper limb, and a microphone measured the impact sound. Resulting signals were analyzed in terms of energy and spectral descriptors. Results showed that flat serves produced louder sounds, higher vibration levels, lower acoustic spectral centroids, and higher vibratory spectral centroids than kick serves. The racket only had a marginal influence. Similarities between acoustic and vibratory measurements were found (levels were correlated), but so were differences (spectral centroids tended to be negatively correlated), encouraging further studies on the link between sound and vibration for the in situ measurement of shock-induced vibration.

There is ample evidence for magnetic reconnection in the solar system, but it is a nontrivial task to visualize, to determine the proper approaches and frames to study, and in turn to elucidate the physical processes at work in reconnection regions from in-situ measurements of plasma particles and electromagnetic fields. Here an overview is given of a variety of single- and multi-spacecraft data analysis techniques that are key to revealing the context of in-situ observations of magnetic reconnection in space and for detecting and analyzing the diffusion regions where ions and/or electrons are demagnetized. We focus on recent advances in the era of the Magnetospheric Multiscale mission, which has made electron-scale, multi-point measurements of magnetic reconnection in and around Earth's magnetosphere. [ABSTRACT FROM AUTHOR]

Soil sensing enables rapid and cost-effective soil analysis. However, a single sensor often does not generate enough information to reliably predict a wide range of soil properties. Within a case-study, our objective was to identify how many and which combinations of soil sensors prove to be suitable for high-resolution soil mapping. On a subplot of an agricultural field showing a high spatial soil variability, six in-situ proximal soil sensors (PSSs) next to remote sensing (RS) data from Sentinel-2 were evaluated based on their capabilities to predict a set of soil properties including: soil organic carbon, pH, moisture as well as plant-available phosphorus, magnesium and potassium. The set of PSSs consisted of ion-selective pH electrodes, a capacitive soil moisture sensor, an apparent soil electrical conductivity measuring system as well as passive gamma-ray-, X-ray fluorescence- and near-infrared spectroscopy. All possible combinations of sensors were exhaustively evaluated and ranked based on their prediction performances using model stacking. Over all soil properties, data fusion demonstrated a considerable increase in prediction accuracy. Five out of six soil properties were predicted with an R2 ≥ 0.80 with the best sensor fusion model. Nonetheless, the improvement derived from fusing an increasing number of PSSs was subject to diminishing returns. Sometimes adding more PSSs even decreased prediction performances. Gamma-ray spectroscopy and near-infrared spectroscopy demonstrated to be most effective, both as single sensors or in combination with other sensors. As a single sensor, RS outperformed three out of six PSSs. RS showed especially potential for fusion with single PSSs but was of limited benefit when multiple PSSs were fused. Model stacking proved to be more robust than using single base-models because sensor performances were less model-dependent.

Irregularities in ionospheric plasma distribution can result in severe scintillation and disruption to the radio frequencies utilized for satellite communications and navigation. In the low and mid latitudes, these irregularities can include Equatorial Plasma Bubbles (EPBs) and Travelling Ionospheric Disturbances (TIDs). EPBs are irregularities manifesting in low latitude nighttime ionosphere plasma density that can extend along magnetic field lines with zonal scales on the order of 100 km or less, while TIDs are propagating wave disturbances. High frequency in-situ measurements of ionospheric plasma aboard spacecraft in Low Earth Orbit (LEO) are a direct measurement of irregularities in plasma density and are therefore valuable for resolving EPB and TID occurrences, variability, and relation to other ionospheric parameters that are believed to play a driving role in the formation of such irregularities. In this study, we utilize observations taken over a three-year period between 2017 and 2020 by the Advanced Ionospheric Probe (AIP) carried aboard the FORMOSAT-5 satellite to examine the spatial, seasonal, and interannual variability of equatorial to mid latitude ionospheric irregularities and vertical ion drift during this time. AIP provides in-situ measurements of ion density and vertical ion drift in the equatorial to mid latitude ionosphere at approximately 720 km altitude with local times between 22:00 – 23:00 local time. Our global scale results resolve distinct and inter-annually recurrent seasonal patterns in the distribution of nighttime ionospheric irregularities and vertical plasma drift during this time. Elevated occurrences of ion density irregularities are resolved along the Equatorial Ionization Anomaly (EIA) latitudes, while notable occurrences with variability consistent with EPBs also observed along the low and equatorial magnetic latitudes. Zonal variability of equatorial irregularities consistent with the signatures of nonmigrating atmospheric tides are observed. It is also notable that the occurrences and geographic distribution of ion density irregularities showed a considerable level of interannual variability, especially at mid latitudes over the South Atlantic and Southern African sectors, which showed much higher levels of irregularities in 2017–––2018, compared to 2019 and 2020. In comparison, the spatial and interannual variation of the co-located vertical ion drifts were much more consistent during the years examined, indicating that the driver for the observed interannual variability in ion density irregularities cannot be attributed to the vertical ion drift at the same time and location of the observations. This highlights the need for in-situ instruments distributed across multiple satellites in different local time zones. [ABSTRACT FROM AUTHOR]

This study, employing the AquaCrop model, demonstrated notable efficacy in assessing and predicting crop yields for winter wheat, maize, winter rapeseed, and sugar beets in the Joint Experiment for Crop Assessment and Monitoring (JECAM) test area of Poland from 2018 to 2023. In-situ measurements, conducted through field campaigns, included parameters such as electromagnetic radiation reflectance, Leaf Area Index (LAI), soil moisture, accumulated photosynthetically active radiation, chlorophyll content, and plant development phase. The model was calibrated with input data covering daily climatic parameters from the ERA5-land Daily Aggregated repository, crop details, and soil characteristics. Specifically, for winter wheat, the Root Mean Square Error (RMSE) values ranged from 1.92% to 14.26% of the mean yield per hectare. Maize cultivation showed RMSE values ranging from 0.21% to 1.41% of the mean yield per hectare. Winter rapeseed exhibited RMSE values ranging from 0.58% to 17.15% of the mean yield per hectare. In the case of sugar beets, the RMSE values ranged from 0.40% to 1.65% of the mean yield per hectare. Normalized Difference Vegetation Index (NDVI)-based predictions showed higher accuracy for winter wheat, similar accuracy for maize and sugar beets, but lower accuracy for winter rapeseed compared to Leaf Area Index (LAI). The study contributes valuable insights into agricultural management practices and facilitates decision-making processes for farmers in the region. [ABSTRACT FROM AUTHOR]

The ultra-short baseline (USBL) positioning system has been widely used for autonomous and remotely operated vehicle (ARV) positioning in marine resource surveying and ocean engineering fields due to its flexible installation and portable operation. Errors related to the sound speed are a critical factor limiting the positioning performance. The conventional strategy adopts a fixed sound velocity profile (SVP) to correct the spatial variation, especially in the vertical direction. However, SVP is actually time-varying, and ignoring this kind of variation will lead to a worse estimation of ARVs'coordinates. In this contribution, we propose a two-step sound speed correction method, where, firstly, the deviation due to the acoustic ray bending effect is corrected by the depth-based ray-tracing policy with the fixed SVP. Then, the temporal variation of SVP is considered, and the fixed SVP is adaptively adjusted according to the in situ sound velocity (SV) measurements provided by the conductivity–temperature–depth (CTD) sensor equipped at the ARV. The proposed method is verified by semi-physical simulation and sea-trail dataset in the South China Sea. When compared to the fixed-SVP method, average positioning accuracy with the resilient SVP be improved by 8%, 21%, and 26% in the east, north, and up directions, respectively. The results demonstrate that the proposed method can efficiently improve the adaptability of sound speed observations and deliver better performance in USBL real-time positioning. [ABSTRACT FROM AUTHOR]

Reinforcement corrosion is a phenomenon that affects not only the durability and serviceability of the structure itself but the economy of the countries, as well. In many cases, structures and bridges must be repaired or reconstructed as a result of corrosion of the reinforcement. In extreme cases, when maintenance is neglected, it is necessary to completely replace the structures with new ones, even if their planned service lifetime has not been reached ‐ it is not enough to strengthen them or it is economically inefficient. Corrosion of the reinforcement primarily causes a reduction in the cross‐sectional resistance of the load‐bearing elements by reducing the cross‐sectional area of the reinforcement, which means a reduction in the force in the reinforcement that it transmits. For this reason, it is necessary to know the rate of corrosion over time depending on the environment in which the element is located. The paper is focused on the experimental measurements of corrosion losses due to atmospheric corrosion on reinforcement samples using the field test. As a part of experimental measurements, corrosion rates on reinforcements of four diameters (diameters 6, 10, 14, and 25 mm) of steel for reinforcement, grade B 500B, are monitored at measuring stations and bridges in various aggressive environments. [ABSTRACT FROM AUTHOR]

Direct energy deposition is an additive manufacturing technique, follows layer-wise deposition to avail design freedom and minimizes material wastage. Despite the unique advantages, repeated heating and cooling induces thermal strains in the components. The present investigation is to understand the thermal-induced distortions and residual stresses in Inconel 718 components fabricated through direct energy deposition. The distortions and temperature measurements are carried out in situ and residual stresses are measured using micro-indentation technique. The distortions are increasing with number of layers, and the distortion rate is varying along the height of deposition. The temperature data indicated rapid heating and cooling. The residual stresses measured are compressive in nature, and are approximately 40% of yield strength in magnitude. The ultimate strength, yield strengths are 800 ± 30 MPa, 580 ± 50 MPa respectively, and maximum hardness obtained is 349 HV. Microstructure Characterizations showed continuous growth of columnar dendrites through multiple layers, and Nb segregation at interdendrites. [ABSTRACT FROM AUTHOR]

Accurate analysis of building energy performance necessitates methodologies that can diagnose the thermal performance of a building's envelope. The building envelope contains various uncertainties and poses difficulties in verifying the measurement results, making it crucial to ensure the reliability of the measurement method. This study used dynamic simulations to verify the accuracy and reproducibility of commonly used field measurement methods. The simulation data were applied to the heat flux meter (HFM) and infrared thermography (IRT) methods to calculate the thermal transmittance of the building envelope and confirm their suitability as a field measurement method. According to the accuracy verification results, the HFM and indoor IRT (IRTi) methods, which are less affected by the external environment, evaluated the actual thermal performance of the wall close to the theoretical value with average relative errors of 3.3% and 4.2%, respectively. In the reproducibility evaluation, the HFM method exhibited similar levels of deviation over time. Additionally, to reduce the deviation in the reproducibility of the thermal transmittance derived from the IRT method, the average method was applied for data analysis, leading to a decrease in the reproducibility deviation from 36.5% to 13.3% for IRTi and from 107.3% to 71.8% for IRT outdoors (IRTo).

• To date, geotechnical instrumentation has been absent from Mars missions. • The Perseverance rover's abrading bit has a similar form factor to a Bevameter. • We study the use of the abrading bit tool to perform soil strength measurements. An instrument for measuring the geotechnical properties of the Martian soil provides high-value science opportunities and high-priority mission-support capabilities that serve reconnaissance, science, and engineering. Such instrument can be used to characterize the terrain for drilling, landing, trafficability, and other surface operations. However, to date, instruments for measuring geotechnical properties have been absent from Mars exploration missions. This paper examines the use of the Mars 2020 Perseverance rover's abrading bit tool to perform regolith strength measurements. The Perseverance rover's abrading bit has a similar form factor to a Bevameter, a tool commonly used to collect engineering geotechnical data to assess terrain traversability. To demonstrate a methodology by which the abrading bit can be employed to characterize soil strength, a portable testbed that mimics the flight system is designed and built using commercial off-the-shelf components. A data-processing pipeline is developed to convert raw measurements to soil strength. Tests were performed on three characterized simulants with different mechanical properties. The results show that the abrading bit is capable of making shear and bearing strength measurements with quantified uncertainties and demonstrate, for the first time, the ability to perform controlled geotechnical analysis using a standard science instrument. [ABSTRACT FROM AUTHOR]

Large knowledge gaps concerning the effect of ocean surface waves on near-surface vertical distributions of temperature and humidity exist due to practical limitations and sensor fidelity challenges of direct measurements. Measurements of temperature and humidity are classically made using rocket- or radiosondes and fixed weather stations and can utilize a tethered profiling system. However, these measurement systems have limitations when obtaining wave-coherent measurements near the sea surface. Consequently, boundary layer similarity models are commonly employed to fill in near-surface measurement gaps despite the documented shortcomings of the models in this region. Thus, this manuscript presents a near-surface wave-coherent measurement platform that measures high-temporal-resolution vertical distributions of temperature and humidity down to ~0.3 m above the instantaneous sea surface. The design of the platform is described along with preliminary observations obtained during a pilot experiment. Ocean surface-wave phase-resolved vertical profiles are also demonstrated from the observations. [ABSTRACT FROM AUTHOR]

Background: As a 3D printing technology, directed energy deposition (DED) has been offering key advantages in additive manufacturing and repair sectors. However, extreme manufacturing processes, such as complex multi-physics coupling process, have brought issues and challenges to the quality and repeatability of DED products. In-situ monitoring in DED process could provide a powerful tool to meet this challenge, and has attracted extensive attention from academic and engineering fields. Objective: In this study, a novel coherent gradient sensing spatial carrier method (CGS-SCM) based on designed prism is proposed for the in-situ monitoring of deformation evolution of DED repaired components. Methods: The measurement principle of the CGS-SCM is analyzed, the governing equations are deduced, and the phase of CGS fringe patterns with carriers are calculated using the sample moiré technique. Moreover, two groups of prisms for carrier generation are designed and integrated into the CGS system, and the new system is verified through the curvature measurement of spherical mirror and the standard four-point beam bending test. Results: Results show that the spatial carrier method could improve both the efficiency and accuracy of data analysis, and the relative error for curvature measurement is less than 2% compared with the strain gauge method. As an application, the evolution rules of the full-field residual deformation of DED repaired components are monitored in situ using the improved CGS system. With the increase of cooling time, the residual deformation shows significant anisotropy and changes in value. In deposition direction, the deformation value gradually increases and the distribution characteristic varies significantly; however, in scanning direction, only the deformation value changes, while the distribution characteristic remains unchanged. Moreover, the deformation in deposition direction is always smaller than that in scanning direction throughout the cooling process. Conclusions: This study indicates that the CGS-SCM based on prisms solves the problem of introducing spatial carriers into CGS optical path, which provides a new way to in-situ analyze the dynamic deformation more efficiently and accurately in DED repair process. [ABSTRACT FROM AUTHOR]

Synchrotron radiation small- and wide-angle scattering measurements have been performed for Mg98.6-Y1-Zn0.4 alloys. In the early stage of phase transformation from supersaturated solid solutions, isotropic scattering suggesting segregation at grain boundaries was observed. It grew with temperature during heating the sample at a constant rate of 0.133K/s. Above 600K where introduction of stacking faults is expected, needle-like scattering became visible, which represents platelet shape segregation of cluster layers called cluster arranged layer (CAL). The layer eventually developed to form multiple layers, cluster arranged nano plates (CANaP) at higher temperatures. Microstructure change by hot rolling after the heat treatments has been examined from a viewpoint of kink-deformed microstructures. [ABSTRACT FROM AUTHOR]

This study investigated the role of bank return flow to two medium size rivers in southeast Queensland using a combination of hydrograph separation techniques and geochemical baseflow separations. The main aims were to provide a case study to demonstrate spatial and temporal variability in groundwater contributions to two river systems in Southeast Victoria; the Avon River and the Mitchell River. The two rivers show large spatial and temporal variations in groundwater contributions with higher percentages during low flow periods and more surface runoff during wet years. At the end of the Australian millennium drought, groundwater discharge accounted for 60% of the total flow for the Avon River and 42% for the Michell River, whereas groundwater discharge only had a minor component to the total discharge in wetter years, ∼15% for the Avon River and only 3% for the Mitchell River. Radon and chloride were used for the geochemical baseflow separation and provide a means to separate regional groundwater discharge to the rivers from bank return flow. Bank return flow accounts for 2 to 5 times higher fluxes in certain areas. Geochemistry in combination with physical hydrogeology enhances the overall understanding of groundwater connected river systems over the river length. [ABSTRACT FROM AUTHOR]

Belarusian Potash salt deposits are bedded under aquifers and unstable soil layers. Therefore, to develop the deposits a vertical mine shaft sinking is performed using the artificial ground freezing technology. Nowadays, real-time observations of ground temperature and groundwater level is applied to control the ground freezing process. Numerical simulation can be used for a comprehensive analysis of measurements results. In this paper, a thermo-hydro-mechanical model of freezing for water-saturated soil is proposed. The governing equations of the model are based on balance laws for mass, energy and momentum for a fully saturated porous media. Clausius-Clayperon equation and poroelastic constitutive relations are adopted to describe coupled processes in water and ice pore pressure, porosity and a stress-strain state of freezing soil. The proposed model was used to predict equivalent water content measured in Mizoguchi�s test and frost heave in a one-sided freezing test. Numerical simulation of ground freezing in the Petrikov mining complex located in Belarus has shown that the model is able to describe field measurements of pore pressure inside a forming frozen wall. Furthermore, the mismatch between hydro- and thermo-monitoring data obtained during the artificial freezing is analyzed.

• Analytical methods and numerical models can determine accurately inner forces in segmental lining. • A comparison is useful between calculation results and in situ monitoring. • Assembly imperfections influence the development of bending moments in segmental linings. • Some common modeling approaches might underestimate the stresses in tunnel linings. • The whole possible parameter bandwidth should be investigated in structural design. Different calculation methods and modeling strategies are commonly used in engineering practice to predict the internal forces in segmental tunnel linings. Accordingly, the calculation results can differ. The present paper compares internal forces resulting from five state-of-the-art calculation models, of which three continuum models and two bedded beam models, to new in-situ measurements of internal forces at the recently built TBM tunnel for the U5 metro line in Frankfurt, Germany, and discusses agreements and differences. Hereby, a generally good agreement is found for the normal forces. The predictions of the bending moments are satisfying, but there are some discrepancies. It is shown that it might be necessary to consider assembly imperfections in the calculation models to improve the agreement between the calculation results and the measurements. Also, the differences between the calculation methods themselves are addressed. It is analyzed that generally continuum models give more realistic internal forces, but that also bedded beam models can have advantages, e.g. when large parametric studies are required. Finally, recommendations are given regarding the application of calculation models for structural design. [ABSTRACT FROM AUTHOR]

Fusion models have been developed to improve the spatial and temporal resolution simultaneously because remote sensing data cannot guarantee the high resolution of vegetation and temperature products. In this study, Moderate Resolution Imaging Spectroradiometer (MODIS) and Land Remote Sensing Satellite (Landsat) data were fused using the STI-FM fusion model for retrieving soil moisture index (SMI) based on the NDVI-LST triangulation/trapezoidal shape. The study was conducted from November 2019 to May 2020 and covered a heterogeneous area in Northern Jordan. For validation, the soil moisture index results were then compared with the observed in-situ soil moisture measurements at 16 sites distributed throughout the study area. To determine the spatial and temporal variability/stability of SMI and observed soil moisture, statistical and geostatistical approaches were employed. The results revealed that the relationship between SMI and in-situ measurements was high in the wet winter months and low during the warm summer months. The determination coefficient r2 of 0.66 and RMSE of 0.10 were found in January while in May, the r2 and RMSE were 0.35 and 0.32, respectively. The results of the semivariogram analysis showed that the observed soil moisture was more varied during the wet periods when compared with the drier period, whereas the SMI was not influenced by seasonal variations. The results indicated that high values of SMI can be obtained with low temperature and rich vegetation, while the higher temperature and water-stressed vegetation revealed low SMI values. [ABSTRACT FROM AUTHOR]

The experimental results of the extremely low frequency emission characteristics excited in the outer ionosphere under the ionospheric plasma heating by high-latitude EISCAT facility are presented. The experiments have been conducted in the period of 2006–2010 yr. using two main schemes of extremely low frequency generation including the impact of the heating facility amplitude modulated emission and two unmodulated pump waves with the frequency detuning. In-situ measurements of the plasma wave disturbances were performed at the outer ionosphere heights using on-board equipment of DEMETER microsatellite. In work the spatial, amplitude and spectral characteristics of the generated extremely low frequency emissions are determined. It is shown that the characteristic size of the extremely low frequency emission is about 400–600 km along the trajectory of the DEMETER microsatellite. The registration area spatial position is determined by both the applied generation scheme and the background plasma density distribution. The extremely low frequency emission electric field strength at the Earth’s outer ionosphere heights is 50–330 μV/m.

According to standards, the lighting system is one of the key elements to provide safety on city roads, defined by quality parameters. LED technology and movement detection sensor interaction bring about new regulation techniques, creating an energy-efficient smart LED lighting system concept. This paper reveals extensive comparative data analysis of Dialux simulation results before the project implementation phase and in-situ quality parameter measurements for various street profiles and LED luminary power types. After the project implementation phase, more than 1000 measurement points are reached. Further, energy efficiency increase issues in smart lighting systems are described in terms of LED luminary dimming profile analysis and future dynamic control application modes. The first findings clearly show that in most cases light output in simulation results is lower than in real situations; therefore, LED luminary power can be decreased, allowing for higher energy savings in first luminary maintenance years, keeping the same defined ME class or safety level. Let us suppose that the traffic intensity data are obtained from smart system sensors. In that case, the ME class can be dynamically selected during different night times, thus increasing safety and providing extra energy savings using the same system elements, as well as leading to better ROI values.

Two measurement campaigns were conducted at Thessaloniki, an urban station, (40.5°N, 22.9°E; 60 m) in the frame of the PANhellenic infrastructure for Atmospheric Composition and climatEchAnge (PANACEA) project. The first one covers the period from July to August 2019 and the second one from January to February An overview of the aerosol optical properties (columnar and height resolved), acquired with the remote sensing infrastructure of the Laboratory of Atmospheric Physics (LAP) of the Aristotle University of Thessaloniki (AUTH), as well as the additional instrumentation that participated during the PANACEA campaigns is presented. The majority of the detected layers (16 out of 40, ranged between 0.8 and 4.5 km) are classified as biomass burning aerosols, attributed to either city sources or long range transport. Concerning the other aerosol types, the Clean Continental cluster has an occurrence ratio of 23%, while dust layers and mixtures with urban particles transported to Thessaloniki are also identified. Our findings are discussed along with the surface information, i.e., the particulate matter (PM2.5 and PM10) concentrations and the black carbon (BC) concentration, separated into fossil fuel (BCff) and biomass/wood burning (BCwb) fractions. This is the first time that collocated in situ and remote sensing instruments are deployed in Thessaloniki in order to assess the presence of aerosols and the predominant aerosol type both in situ and at elevated heights. Overall, our study showed that the BCwb contribution to the BC values in Thessaloniki is quite low (11%), whilst the majority of the biomass burning layers identified with the lidar system, are also linked with enhanced BC contribution and high Fine Mode Fraction values. [ABSTRACT FROM AUTHOR]

Although variable well log resolution and its control on saturation estimation has been studied, it has not been directly applied to a specific location to explore the nature of gas hydrate within a sand reservoir. We applied in-situ measurements of resistivities, neutron porosity, and gamma ray at two sites in the Qiongdongnan Basin, South China Sea (QDN-W05–2021 and QDN-W08–2021) to investigate the reservoir parameters of a hydrate-bearing sand reservoir. Our results show that gas hydrate is distributed in 5 zones with a total thickness of 10.7 m and an average saturation of 69% at the QDN-W05–2021 site, while they are distributed in 2 zones with a total thickness of 4.3 m and an average saturation of 49% at the QDN-W08–2021 site. We found that variances in saturations estimated from lateral-extra deep button (RX), phase shift (P40H-P40L), and attenuation (A40H-A40L) resistivities within the laterally mapped continuous sand body were affected by the nature of gas hydrate occurrences. Results indicate gas hydrate forms and accumulates at the center of the sand layer and tends to be less or not present toward the top and base. Integrated with seismic data, the in-situ measurements provide insights in the evolution of a mushroom-shaped, hydrate-gas reservoir system. In the system, free gas is likely horizontally transported from the top-center of the gas chimney to the surrounding areas in the early stage dominated by a warm-gas environment, whereas hydrate forms in the opposite pathway starting from the surrounding areas in the following stage with temperature reducing. Our study suggests that high-resolution in-situ measurements not only are a tool to identify the physical properties, but also can be used to help explain the physical process of hydrate growth and accumulation. • We identify a hydrate-bearing sand reservoir with multiple thin, horizontal beds. • Mushroom-shape hydrate-gas system via lateral fluid movement from a gas chimney. • Thin, lateral-bedding hydrate layers results in electrical anisotropy. • Thin gas hydrate reservoir shows more pronounced saturation scale effects. • Vertical resolution of resistivity tools influences hydrate saturation estimates. [ABSTRACT FROM AUTHOR]

The lubricating effectiveness of an oil film in a journal bearing depends on the dynamic viscosity of the oil. The viscosity in turn depends on the local operating temperature, pressure, and shear rate. Reproducing these conditions in a laboratory viscometer to investigate the lubricant behaviour is a challenging task. As a result, methods that allow oil viscosity measurement in-situ in a film, would be preferred. Ultrasound technology utilising shear bulk acoustic waves (BAW) has been used to measure liquid viscosity in the bulk, as well as in-situ in a film; the reflection of a shear BAW from a solid-liquid interface depends on the liquid viscosity. Surface acoustic waves (SAW) have been also used for measuring bulk liquid viscosity. In this paper, shear-horizontal surface acoustic waves (SH-SAWs) were explored for measuring oil film viscosity, as they present good coupling with liquids and sensitivity to surface changes. The main objectives of this work were to generate SH-SAWs on metallic media, investigate the wave response at the metal-oil interface, relate the wave response to viscosity with the aim to apply this knowledge to a journal bearing application for measuring viscosity in-situ the lubricant film. Initially, the SH-SAW response was investigated at a solid-liquid interface. SH-SAWs attenuate at the solid-liquid interface, due to the liquid viscosity. This was modelled as a function of the liquid properties, material and geometry of the medium, and wave frequency. The SH-SAW attenuation-viscosity model was used to calculate the viscosity (in the range of ∼3 to 4600 cP) of different oils at a free surface, which agreed with the viscosity values from datasheets and bench-top viscosity measurements. This approach was then implemented in-situ in a journal bearing application. A bearing sleeve was instrumented with a pair of SH-SAW transducers and a shear BAW transducer installed inside the rotating journal. These two approaches were used to measure the film viscosity of 4 lubricants blended with different additives in two ways; the former by the leakage of the surface wave, and the latter by the reflection of the bulk wave. Both approaches were found to be in good agreement. They successfully distinguished the chemistry of the oil test samples according to their viscosities under various loading conditions and constant speed, and were able to monitor changes in the oil film viscosity in the loaded region. The SH-SAW sensors used were low cost and small sized and so can be fitted relatively conveniently into a bearing sleeve, requiring nothing but a function generator and digitiser to operate. This approach could then be used to evaluate lubricant formulations for their performance actually inside a bearing, rather than through the extrapolation of data from a conventional bench top viscometer. [ABSTRACT FROM AUTHOR]

Belarusian Potash salt deposits are bedded under aquifers and unstable soil layers. Therefore, to develop the deposits a vertical mine shaft sinking is performed using the artificial ground freezing technology. Nowadays, real-time observations of ground temperature and groundwater level is applied to control the ground freezing process. Numerical simulation can be used for a comprehensive analysis of measurements results. In this paper, a thermo-hydro-mechanical model of freezing for water-saturated soil is proposed. The governing equations of the model are based on balance laws for mass, energy and momentum for a fully saturated porous media. Clausius-Clayperon equation and poroelastic constitutive relations are adopted to describe coupled processes in water and ice pore pressure, porosity and a stress-strain state of freezing soil. The proposed model was used to predict equivalent water content measured in Mizoguchi's test and frost heave in a one-sided freezing test. Numerical simulation of ground freezing in the Petrikov mining complex located in Belarus has shown that the model is able to describe field measurements of pore pressure inside a forming frozen wall. Furthermore, the mismatch between hydro- and thermo-monitoring data obtained during the artificial freezing is analyzed. [ABSTRACT FROM AUTHOR]

Detailed knowledge of the physical and chemical properties and sources of particles that form clouds is especially important in pristine areas like the Arctic, where particle concentrations are often low and observations are sparse. Here, we present in situ cloud and aerosol measurements from the central Arctic Ocean in August–September 2018 combined with air parcel source analysis. We provide direct experimental evidence that Aitken mode particles (particles with diameters ≲70 nm) significantly contribute to cloud condensation nuclei (CCN) or cloud droplet residuals, especially after the freeze‐up of the sea ice in the transition toward fall. These Aitken mode particles were associated with air that spent more time over the pack ice, while size distributions dominated by accumulation mode particles (particles with diameters ≳70 nm) showed a stronger contribution of oceanic air and slightly different source regions. This was accompanied by changes in the average chemical composition of the accumulation mode aerosol with an increased relative contribution of organic material toward fall. Addition of aerosol mass due to aqueous‐phase chemistry during in‐cloud processing was probably small over the pack ice given the fact that we observed very similar particle size distributions in both the whole‐air and cloud droplet residual data. These aerosol–cloud interaction observations provide valuable insight into the origin and physical and chemical properties of CCN over the pristine central Arctic Ocean. Key Points: Aitken‐mode particles contributed significantly to cloud droplet formation in the high Arctic, especially after the transition to fallResidence time over the pack ice and the relative contribution of organics both increased when average particle size decreasedAddition of aerosol mass due to aqueous‐phase chemistry was probably small over the pack ice [ABSTRACT FROM AUTHOR]

In addition to the duration and intensity of rainfall, infiltration processes are strongly affected by the hydraulic properties of the soil. In the case of heterogeneous and stratified soil profiles, the analysis of the infiltration process becomes more complex, since conflicting hydraulic properties of adjacent layers can induce locally diverted flow. Soils of volcanic origin present these characteristics, because during the various eruptive phases, layers with very different textures are deposited. In this article, data are analysed which have been recorded by a monitoring station installed on a slope made up of volcanic deposits. The station consists of a rain gauge to measure rainfall and seven tensiometers and eight TDR probes installed at different depths to measure suction and volumetric water content, respectively. The slope is made up of alternating volcanic ash (silt‐sandy‐clay paleosoils) interspersed with pumice (sandy‐gravel), due to the different eruptive phases of the volcanic complexes in the area. The analysis of the data established that the layers of coarser material (pumices), depending on the initial moisture conditions, may hinder or even favour the infiltration of water into the deeper layers. In particular, when water content is low, the pumices presented a low unsaturated conductivity which hindered infiltration. By contrast, in wetter conditions, they favoured the flow of water. Therefore, the initial moisture conditions of the soil layers must be taken into account for a correct prediction of the infiltration phenomena. Dry conditions of the pumice layers can hinder drainage into the lower layers, thus favouring the rapid accumulation of soil water during rainfall events, which could eventually lead to slope failure. [ABSTRACT FROM AUTHOR]

This article presents the application of data from the real-time full-scale long-term monitoring of mine-induced vibrations in one of the mining districts in Poland in the study of the soil-structure interaction (SSI) effect. Mining-related surface vibrations constitute a burdensome and essential problem in mining areas all over the world because underground exploitation results in so-called induced seismicity with a negative vibration impact on the environment and may damage structures. Mining tremors are similar to natural earthquakes due to, for example, their randomness, lack of human control, time and place of their occurrence and energy magnitude. As a consequence of the SSI phenomenon, mine-induced vibrations concurrently measured on the free-field near to the building and at the building foundation level may differ significantly. Long-term measurements using dynamic tensometers permit the establishment of strength states in structural elements and the evaluation of the health of materials and structures. Long-term observations also indicate the development of damage over time and its propagation in the structure. Dimensionless response spectra (β) were applied for describing the seismic-type loads from mine-induced tremors – such spectra are found in many design codes. An evaluation of the influence of mining parameters (epicentral distance, energy magnitude, peak ground acceleration) on the process of the transition of ground accelerations to the structure foundations was performed using curves of ratios of β from vibrations recorded concurrently on the free-field and in the building foundation. The strong influence of the rockburst parameters on β curves achieved with the application of free-field and foundation mining-related records is observed. A similar conclusion applies to the ratios of β concerning low-, medium-, and high-rise buildings with different load-bearing systems. Furthermore, based on the results obtained from measurement data, empirical models for the simple estimation of the SSI effect were proposed.

Heat exchange between environment and workpiece during a manufacturing process can lead to temperature gradients and strains within the workpiece and can result in residual stresses. The correlations between the generated thermal loads and the resulting modifications are called Process Signature. The presented investigations were performed to validate residual stress calculations for laser hardening. Furthermore, the potential of speckle photography for in-situ measurement of displacements as an additional result for simulation validation were evaluated. [ABSTRACT FROM AUTHOR]

Virgin olive oil quality is assessed by chemical as well as sensory analysis. Two of the most important parameters that define the quality of virgin olive oils are the free acidity and the peroxide index. These chemical parameters are usually determined by manual titration procedures that must be carried out in a laboratory by trained personnel. In this paper, a portable sensor system to support the quality grade assessment of virgin olive oil is presented. The system is battery operated and characterized by small dimensions, light weight and quick measurement response (about 30 s). The working principle is based on the measurement of the electrical conductance of an emulsion between a chemical reagent and the olive oil sample. Two different chemical reagents have been investigated: (1) a hydro-alcoholic solution (HAS), made of 60% ethanol and 40% distilled water; (2) 100% distilled water (DW). Tests have been carried out on a set of 40 olive oil samples. The results have shown how, for most of the fresh virgin olive oil samples (31 samples out of 40), the free acidity can be estimated with good accuracy from the electrical conductance of the emulsion using HAS as the reagent. In the case of the full set of samples, the emulsion electrical conductance, using HAS as the reagent, is a function of both the sample free acidity as well as the compounds produced by oil oxidation, and a compensation method based on the measured electrical conductance, using DW as the reagent, has been introduced to improve the accuracy in the estimated free acidity. Tests have also been carried out on the full set of samples, using a k-nearest neighbors algorithm, to demonstrate the feasibility of olive oil classification according to the quality grade. The results have shown how measurements carried out using only the HAS reagent provide better classification accuracy than measurements carried out using both the HAS and DW reagents. The proposed system can be a low-cost alternative to standard laboratory analyses to evaluate the quality grade of virgin olive oil. [ABSTRACT FROM AUTHOR]

This study provides evidence that a helium-neon (He-Ne) laser operating in the Mid-infrared (MIR) at a wavelength of 3.39 μm can detect variations in 1-hexene concentration in the presence of a solid catalyst. The in-situ and online characterization of the concentration of 1-hexene, as an example of a hydrocarbon, is relevant to enhance the current understanding of the interaction between hydrodynamics and chemistry in different heterogeneous catalytic processes. We designed and built a laboratory-scale downer unit that enabled us to analyze heterogeneous catalytic reactions and provided optical access. The lab-scale reactor was 180-cm long, had an internal diameter of 1.3 cm, and was made of fused quartz to allow the passage of the laser beam. 1-hexene was carefully measured, vaporized, and fed into the reactor through two inlets located at an angle of 45 degrees from the vertical descendent flow and 70 cm below the input of a solid catalyst and a purge flow entraining N2. A system of five heaters, which can be moved in the vertical direction to allow the passage of the laser beam, guaranteed temperatures up to 823 K. Computational Fluid Dynamics (CFD) simulations of the hydrodynamics of the system indicated that a uniform temperature profile in the reaction section was reached after the catalyst and the feed mixed. The estimated catalyst to oil ratio and time on stream in the experiments were, respectively, 0.4 to 1.3 and 2 s. After a correction for laser power drift, the experimental results showed a linear response of the fractional transmission to the 1-hexene concentration that was independent of temperature in the 373 K–673 K range. Even in the presence of a catalyst, the absorption of 1-hexene at the MIR frequency of the laser was high enough to enable the detection of 1-hexene since the fractional absorption of the absorbing path length in these experiments was close to zero (0.013 m) and the 1-hexene concentrations were higher than 1.254 × 10-5 mol/cm3. This result demonstrated the ability of the laser system to measure the concentration of 1-hexene in the presence of a catalyst and indicates that it can be used to better decouple hydrodynamics from kinetics in heterogeneous catalytic processes.

The large-scale structure and evolution of the solar wind are typically reproduced with reasonable fidelity using three-dimensional magnetohydrodynamic (MHD) models. However, such models are difficult to implement by the scientific community in general, because they require technical expertise and significant computational resources. Previously, we demonstrated how a simplified two-dimensional surrogate solar wind model, the Heliospheric Upwind eXtrapolation (HUX) technique, could reconstruct MHD solutions in the ecliptic plane, given either an inner (or outer) radial boundary condition. Here, we further develop the HUX technique and apply it to a range of solar wind in-situ datasets. Specifically, we: (1) provide a thorough mathematical analysis of the underlying reduced momentum equation describing the solar wind. (2) Propose flux-limiter numerical schemes that more accurately capture stream interaction regions and rarefaction regions; and (3) Apply the HUX technique to a variety of in-situ spacecraft measurements, focusing on Helios (1 and 2) and near-Earth spacecraft (Wind/ACE), for which near-latitudinal alignments occurred. We suggest that this refined HUX tool can be used for both retrospective studies as well as real-time predictions to better understand and forecast the large-scale structure and origin of the solar wind.

2D materials and their heterostructures (HSs) hold great promises for a number of future applications, owing to their unique layered structure and excellent properties, both of which can be tuned by a number of techniques. Among various tuning methods, pressure engineering using diamond anvil cell (DAC) is a highly effective in-situ and reversible technique, which can efficiently modulate the structure and physical properties of 2D materials. In this review, we survey recent researches based on pressure engineering in 2D materials and HSs, focusing on the advantages and challenges in experimental study using DAC, as well as the combination of high-pressure capability with other experimental techniques for in-situ characterization of structural, optical, and electrical properties, all under high pressure.