Depth Sections Research Articles

Estimations of Secchi depth from the turbid Eastern China Coastal Seas using MODIS data

ABSTRACT In this study, a neural network-based Secchi depth retrieval model (NNSD) was developed using observations obtained during 2003–2012 in the Bohai, Yellow, and China East Seas (Eastern China Coastal Seas, ECCS). Based on the results of the analyses, the NNSD model produced less than 25% uncertainty in quantifying the Secchi depth in the optically complex ECCS. The slope of the linear relationship between the field-measured and NNSD model-derived Secchi depth varied from 0.98 to 1.08 among the datasets. However, the corresponding determination coefficients were not any lower than 0.91. To determine the effectiveness of the NNSD model in deriving the Secchi depth in the ECCS, the performances of the three existing models were also evaluated, and the results are presented in this study. By comparison, using the NNSD model decreased the uncertainty by 26% when compared with the three existing models in deriving the Secchi depth in the ECCS. Finally, the NNSD model was further applied to the MODIS data over the ECCS to briefly illustrate its applicability to general oceanographic studies. The NNSD model could produce 24.62% MRE and 0.14 RMSE values in deriving the Secchi depth from the ECCS, which was > 26% MRE and > 0.07 RMSE values better than all the BGSD, KDSD and SASD models. In regards to the spatial distribution pattern of the Secchi depth, the eastern and northern sections of the ECCS were much higher than the western and southern areas. Additionally, the temporal distribution mode indicated that the winter season was higher than the summer season. These spatiotemporal characteristics were caused primarily by the regional climate, river discharges, and strong tidal currents and winds, among other factors.

The nonlinear analysis of tapered steel section with opening due to the effects of bending behavior

PurposeTapered steel sections are widely used in house building design due to their structural efficiency and aesthetic appearance. Due to the practical usage of web tapering specifications in the metal building industry, fabrication and material expenses are analyzed to achieve geometric and economic productivity. The purpose of this study is to investigate the effectiveness of utilizing web profiles with openings in reducing the weight of steel beams.Design/methodology/approachIn this paper, the nonlinear analysis of the bending behavior of a tapered steel section with an opening was studied by finite element analysis. The results were then compared with those of the tapered steel section without an opening in terms of displacement and yield moment.FindingsThe bending capacity of a tapered steel section was analyzed using finite element analysis. Results showed that the tapered steel section without openings had a higher bending capacity compared to the section with various sizes of web openings. The results also showed that decreasing the number of openings would increase the bending capacity, whereas increasing the size of the opening would decrease it. The difference in the yield moment between the tapered steel section with and without openings was only 15.818%. A total of 60 nonlinear analyses were conducted to investigate the effect of the number and size of web openings, flange thickness and web thickness on the bending behavior. However, this study showed that web opening with octagon shape and 0.6D size of web opening, where D is the depth of section, showed the best section in terms of yield moment and volume reduction compared to other opening size and shape.Originality/valueIt is also found that tapered steel section has better moment resistance in thicker flange and web. The study is valuable for engineers and designers who work with steel structures and need to optimize the performance of tapered steel sections with web openings.

Dowel behaviour of rebars under combined axial and shear actions

The resource of shear resistance provided by the dowel mechanism of rebar in reinforced concrete (RC) structures can significantly affected by the simultaneous presence of axial loading. This occurs for example of plastic hinges of seismic resistant structures. In fact, at load reversals in cycles of large deformation demand, rebars are subjected to combined axial and shear loading, particularly in those section where the shear transfer via aggregate interlocking is jeopardized by the opening of the crack throughout the entire section depth. Thus, a reliable assessment of the shear capacity of dowels under combined shear and axial load is required to check the element shear resistance. The paper describes the results of a specific experimental campaign on rebar dowels subjected to shear loading in presence of different levels of axial load. Both smooth and ribbed rebar dowels were investigated. A marked reduction of the dowel shear strength and stiffness in presence of increasing axial loading was experimentally observed, only partially compensated by the kinking effect. The latter was found to characterize the entire resource of dowel capacity when the axial load was close to the rebar yielding strength. The paper proposes an analytical model, adapted from others available in the literature, to predict the dowel shear-displacement response accounting for the applied axial load. The model helps the understanding of the dowel response, is suitable for hand calculation and can easily assist the dowel design. The experimental response was quite well captured for smooth dowels, while the prediction was less accurate for ribbed ones. Future refinements may address the local damage induce by the rebar pull-out, typical of ribbed rebars, which is neglected in present form of the model.

Development of a novel real-time AE source localisation technique using ANN for health monitoring of rail section: an experimental study

Almost all countries are using railways to transport passengers and freight. Due to heavy load and environmental exposure, these rail sections are prone to damage. Thus, structural health monitoring of the rail section is an essential topic of research to ensure safety and predict the remaining useful life of the track. Consequently, the detection and localisation of damages/cracks in rail section are crucial. It also helps in taking corrective action in time. In this context, the acoustic emission (AE) technique is found to be a powerful non-destructive testing technique which has great potential to localise cracks in rail sections. Actually, the initiation or growth of a damage/crack in a structure emits AE waves, which may be captured using AE sensors mounted on different locations of the structure. The damage itself acts as an AE source. Subsequently, in this study, a novel approach is developed to localise the AE source in a rail section using the artificial neural network (ANN). The ANN model is based on the experimental crack signals captured through a single AE sensor by placing it at different regions of the rail section. For each position of the sensor, cracks are simulated using pencil lead break at different locations along the length and depth of the rail section. It is observed that the developed ANN model predicts the location of the AE source with better accuracy in comparison to the existing localisation methods. The minimum error is found to be less than 1%. Therefore, it can be concluded that the developed ANN model is a suitable option for predicting potential crack locations during real-time monitoring of rail sections.

Опыт применения неинвазивных методов геофизики при решении задач археологии

На сегодняшний день в мировой практике применение неинвазивных геофизических методов при решении археологических задач является неотъемлемой частью работ на начальном этапе исследований. В статье рассматривается опыт применения малоглубинной геофизики на различных археологических объектах Наманганской, Джизакской и Сурхандарьинской областей Республики Узбекистан. Целью работ являлось изучение древних погребений курганного типа, выделение культурного слоя на местах стоянок древних людей, а также исследование построек и объектов жизнедеятельности городищ Кушанского периода территории Северной Бактрии. Исследования проводились лабораторией «Геофизики и наноминералогии» Центра передовых технологий комплексом геофизических методов, включающем в себя магниторазведку, георадиолокационную съемку и электротомографию (ЭТ). Магнитная съемка проводилась с помощью протонных магнитометров Geometrics 856АХ (США), при этом расстояние между датчиками составляло 50 см, таким образом шаг между точками измерений и профилями составлял 50 см. Георадарные измерения выполнялись георадаром PulseEKKO PRO компании Sensors & Software (Канада) по системе сеточных профилей с шагом между профилями 1 м и антенной с центральной частотой 100 МГц. При электроразведочных измерениях методом ЭТ использовался 72 электродный георезистивиметр M.A.E. X-612EM (Италия) различными расстановками с учетом глубины и размеров объекта исследований. Применение геофизических методов позволяет определять различные археологические объекты в соответствии с изучаемым физическим полем, тем самым комплексирование методов дает возможность получить объектно-направленную информацию, при этом не нарушая целостность изучаемых объектов. В результате обработки и интерпретации полевого материала были получены карты, схемы, разрезы и глубинные срезы по геофизическим данным в пределах исследованных площадок с выделением аномалий, которые могут быть связаны с археологическими объектами. Результаты проведенных раскопок, подтверждают достоверность исследований.To date, in world practice, the use of non-invasive geophysical methods in solving archaeological problems is an integral part of the work at the initial stage of research. In the article the experience of using near-surface geophysics on different archaeological sites of Namangan, Djizak and Surkhandarya regions of the Republic of Uzbekistan is considered. The aim of the work was to study ancient burials of kurgan type, to identify cultural layer at the sites of ancient people standing and to study constructions and objects of vital activity of the Kushan period sites in the territory of Northern Bactria. Researches were carried out by the laboratory “Geophysics and nanomineralogy”of the Center of Advanced Technologies by a complex of geophysical methods including magnetic surveying, georadiolocation surveying and electrotomography (ET). The magnetic survey was carried out using Geometrics 856AX proton magnetometers (USA), with a distance of 50 cm between the sensors, so the step between the measurement points and the profiles was 50 cm. GPR measurements were carried out with a PulseEKKO PRO georadar of Sensors&Software company (Canada) using a grid profile system with a step between profiles of 1 m and an antenna with a central frequency of 100 MHz. During the electrical prospecting measurements by ET method a 72-electrode M.A.E. georesistivity meter was used. X-612EM (Italy) was used with different formations taking into account depth and size of the investigation object. Application of geophysical methods allows to determine different archaeological objects in accordance with the physical field under study, thereby the combination of methods makes it possible to obtain object-directed information, while not violating the integrity of the objects under study. As a result of processing and interpretation of field material were obtained maps, diagrams, sections and depth sections on geophysical data within the investigated sites with the allocation of anomalies that may be associated with archaeological objects. The results of the excavations, confirm the reliability of the research.

The Optimization of Segmented Reaming Parameters and the Analysis of the Pressure Relief Effect in Impacted Coal Seams

This work focused on the insufficient or excessive pressure relief in large-diameter pressure relief by drilling. The influence of large-diameter pressure relief by drilling on the 6307 working face of the Tangkou coal mine on the roadway deformation was taken as the research background, with numerical simulations, indoor experiments, and on-site applications used. The influence of pressure relief drilling on roadway deformation was studied to propose segmented reaming pressure relief. The influences of parameters (e.g., reaming diameter, reaming depth, and borehole spacings) on the evolution characteristics of segmented reaming cracks and pressure relief were further investigated. The results showed that segmented reaming pressure relief reduced the roadway deformation and the peak elastic energy of coal in the impacted hazard area and improved the energy accumulation of the surrounding rocks of the roadway. The effect of segmented reaming pressure relief was positively correlated with the diameter and length of the reaming section; it was negatively correlated with borehole spacings. The optimized segmented reaming parameters of the 6307 working surface of Tangkou coal mine are as follows: the optimized reaming diameter of 240 mm, the reaming section depth of 15 m, and the borehole spacing of 1.6 m. Field tests proved that the optimized segmented reaming technology can improve the deformation of the surrounding rocks of the roadway and construction.

Importance of drilling-related processes on the origin of borehole breakouts — Insights from LWD observations

Logging while drilling (LWD) images are widely used for the analysis of borehole stability. In this context, borehole breakouts are a crucial indication of rock failure developing when the circumferential stress around the borehole exceeds the yield value of the rock. This study investigates the impact of drilling-related processes (DRPs) on the origin of borehole breakouts. DRPs, for instance, include connections or tripping operations. For this purpose, we analyze data from 12 boreholes in different geological settings throughout the Norwegian and Danish North Sea, containing a total of 208 borehole breakouts. The extensive data acquisition of LWD offers the unique possibility to link the imaging to real-time drilling operations and to monitor anomalies of e.g., bottom hole pressure. These records allow us to connect any thermal, hydraulic, or mechanical interaction next to the borehole wall to perturbations of the stress field. This analysis resulted in an apparent strong coincidence of borehole breakouts, representing major stress perturbations, with DRPs. The causal relationship is highlighted by one order of magnitude higher occurrence of DRPs in depth sections containing breakouts. Major pressure reductions in the annulus of the borehole seem to be the most significant cause of drilling-related wellbore failures. This applies in particular to shutting off the pumps during connections, where pressure reductions of up to 16 % of the annulus pressure led to higher circumferential stresses. This process will increase the likelihood of compressive and shear failure, therefore causing borehole breakouts. These observations further open the perspective of counteracting wellbore instabilities by pressure modification. In addition to the initiation of breakouts, their temporal evolution – as seen in relogs – can also be ascribed to DRPs. This study indicates that not only plasticity but also mechanical interaction from DRPs is a key driver of the temporal growth of borehole breakouts.

Semi-empirical synergetic analysis of the shear capacity of steel fibre reinforced concrete slender beams of rectangular-sections without stirrups

Although steel fibre reinforced concrete (SFRC) has been widely used in various engineering structures, there is a lack of a reliable and unified method for predicting the shear capacity of reinforced SFRC slender beams. After conducting an extensive review of previous studies on the slender beams of rectangular-section without stirrups and the SFRC with the cold-drawn hook-end steel fibre, a database was developed based on 280 reinforced SFRC slender beams that failed in shear accompanied by 37 reinforced SFRC slender beams failed in flexure and 71 reinforced conventional concrete beams failed in shear. The comparison between the experimental results and the results predicted using existing formulae revealed that a more accurate empirical model is required to evaluate the effects of multi-factors on the shear strength of the reinforced SFRC slender beams without stirrups. Based on the model of the critical shear crack, a semi-empirical synergetic equation is developed to predict the shear capacity of reinforced SFRC slender beams without stirrups. The enhanced shear resistance of SFRC in the shear-compression zone, the dowel action of longitudinal tensile steel bars, the aggregate interlock between sides of critical shear crack, and the shear resistance of steel fibres across the shear cracks as well as the size effect of sectional depth are considered. Good prediction results with small dispersion can be obtained using the proposed semi-empirical model. Conservative and simplified equations are also provided as the lower bound of the experimental shear strength of the reinforced SFRC slender beams without stirrups for easier implementation of the proposed model in real engineering design practice.

Heat flow variations in 2 km deep borehole Litoměřice, Czechia

Temperature in 2 km deep borehole Litoměřice, drilled in 2007, was repeatedly logged down to 1700 m in the period 2007 – 2020. We were able to monitor a return of the temperature to the equilibrium temperature-depth profile undisturbed by drilling. The uppermost part of the profile contains signal of the recent warming manifested by a negative temperature gradient close to the surface and a temperature minimum at a depth of about 40 m. The minimum has been migrating downward at a rate of 1.5 – 2 m per year in the period 2015 – 2020.A detailed knowledge of temperature gradient together with thermal conductivity, diffusivity and heat production measurements on the drill-core samples of mica-schist that occurs below 900 m depth enabled us to analyze the heat flow vertical variations in the lithologically homogeneous depth section 900 – 1700 m. We came to the conclusion that temperature-depth profile in this section contains a robust climate signal of the last glacial cycle. The reconstructed ground surface temperature history indicates the magnitude of the last glacial – Holocene warming 13 -15 K and existence of a minimum 15 – 20 ka. The long-term mean ground surface temperature +1 - +2 °C suggests that the borehole site was permafrost free for most of the glacial cycle. Existence of about 100 m deep permafrost is possible in the coldest part of the last glacial.The steady-state surface heat flow has been estimated at 88 mW/m2. The reconstructed ground surface temperature history used as a surface forcing function in a numerical solution of the transient heat conduction equation provided an estimate of the present-day heat flow in the well. The estimate is practically independent from the poorly constrained conductivity of the 900 m thick sedimentary cover. According to it the present-day heat flow is lower than the steady-state one by 20 - 30 mW/m2 in the first hundreds of meters below the surface and still by about 10 mW/m2 at a depth of 1 km.

Charring Depth and Deflection Behavior of Cross Laminated Timber Floor under Fire

本研究透過進行日本扁柏及北美花旗松此兩種日本及北美常見的材種所製成的CLT樓板，進行1小時火害實驗，並探討其炭化深度及撓曲變形行為。由實驗結果可知日本扁柏CLT樓板之有效炭化速率約為0.77mm/min～0.87mm/min；北美花旗松CLT樓板之有效炭化速率約為0.63mm/min～0.82mm/min。實驗結果與文獻之炭化深度有相近。另外，兩組樓板CLT之炭化深度經量測觀察，分別都可發現在CLT板拼接處有較大的炭化深度產生。由於拼接處無法如同板本身緊密接合，因此會有火源竄入並造成較深的炭化層。樓板的撓曲變形行為方面，本研究亦參考國外規範，進行火害時由於炭化層產生，導致樓板整體勁度下降，以致整體撓度會有持續加大的評估方法進行探討。由評估結果可顯示，當曝火面第1層完全炭化，底層主軸由曝火面第1層集成元的強軸變為曝火面第2層集成元的弱軸，因此造成撓度大幅度的增加。然而，CLT板同層各集成元間並沒有進行側拼膠合，故在燃燒時，集成元間會因為受載重的影響產生縫隙，使得火焰經由縫隙對第3層的強軸集成元進行燃燒，亦可從實驗數據中觀察到此強軸集成元（曝火面第3層）受到火害的影響的行為。Cross Laminated Timer (CLT) become one of the most popular Engineered wood recently, especially for the midrise and high-rise building. In Taiwan, the fundamental data for design, such as fire design or structural design are not sufficient, more research need to be conducted. In this study, the behavior of CLT under 1 hour burning was carried out, in order to obtain the experimental results for the establishment of Building code in Taiwan.In this study, totally 2 CLT specimens was prepared for the fire testing, including 1 Japanese Cypress CLT floor, and 1 Douglas Fir CLT floor. Charring depth, charring ratio, and residual section are measured after 1 hour fire burning. The testing results indicate that the charring ratios of these specimens are generally higher than the research results from reference, although the difference are limited. It is observed that the residual stiffness is greatly influenced by the strong axis layers of the CLT panel, the deflection is dramatically increased when the first layer disappeared. The testing results give government a fundamental data and reference for further code revision regarding the fire behavior of CLT panels.

Estimating Groundwater Recharge in Fully Integrated pde‐Based Hydrological Models

AbstractGroundwater recharge is the main forcing of regional groundwater flow. In traditional partial‐differential‐equation (pde)‐based models that treat aquifers as separate compartments, groundwater recharge needs to be defined as a boundary condition or it is a coupling condition to other compartments. Integrated models that treat the vadose and phreatic zones as a continuum allow for a more sophisticated calculation of subsurface fluxes, as feedbacks between both zones are captured. However, they do not contain an explicit groundwater‐recharge term so it needs to be estimated by post‐processing. Groundwater recharge consists of changes in groundwater storage and of the flux crossing the water table, which can be calculated based on hydraulic gradients. We introduce a method to evaluate the change of groundwater storage by a time‐cumulative water balance over the depth section of water table fluctuations, avoiding the use of a specific yield. We demonstrate the approach first by a simple 1‐D vertical model that does not allow for lateral outflow and illustrates the ambiguity of computing groundwater recharge by different methods. We then apply the approach to a 3‐D model with a complex topography and subsurface structure. The latter example shows that groundwater recharge is highly variable in space and time with notable differences between regional and local estimates. Local heterogeneity of topography or subsurface properties results in complex redistribution patterns of groundwater. In fully integrated models, river‐groundwater exchange flow may severely bias the estimate of groundwater recharge. We, therefore, advise masking out groundwater recharge at river locations.

Sustainable Use of Tire-Derived Aggregate in the Protection of Buried Concrete Pipes under Combined Soil and Traffic Loads

Tire-derived aggregate (TDA) has been used successfully as a backfill soil to reduce the applied stresses on buried steel pipes. The preceding study, however, paid no attention to inspecting the TDA efficiency of buried concrete pipes subjected to soil and traffic loads. In addition, it is not clear how the TDA material, traffic loading, burial depth, and road section affect the pipe-bending moment. Therefore, this paper examines the efficiency of TDA in reducing the bending moment of a 0.6 m concrete pipe subjected to combined soil and traffic loads using a validated three-dimensional finite element model. Two trench configurations have been constructed, the first is composed completely of well graded sand, and the second is similar to the first except for the 150 mm layer on the top of the pipe crown, which is replaced with TDA. Furthermore, three road sections (highway, public road, and unpaved road) have been adopted to provide an intensive understanding of the TDA effect for different road conditions. A parametric study is carried out to detect the effect of the burial depth, road section, and traffic load on the efficiency of the TDA of the buried pipe. It is observed that the TDA has no effect on the bending moment distribution around the pipe. Additionally, the TDA reduces the bending moment developed in the pipe wall with a percentage decrease range between 18% and 42% depending on the burial depth and road section. Furthermore, it is also found that the efficiency of the TDA in reducing the maximum bending moment decreases as the burial depth increases. In addition, the best performance for the TDA is found at a burial depth of 1.0 m for all road sections. Importantly, the best performance for the TDA is found for the highway section compared with the other sections, with a maximum percentage decrease of 42% compared to 27% for the public road section and 26% for the unpaved road section.

Design and Test of Air-Assisted Seed-Guiding Device of Precision Hill-Seeding Centralized Seed-Metering Device for Sesame

Sesame seeds are flat and oval, with poor mobility, easily blocking a seed tube and reducing seeding quality. An air-assisted seed-guiding device was designed for a hill-seeding centralized seed-metering device for sesame. The core of the seed-guiding device is a distribution manifold that could restrict the trajectory of seeds and make seeds move in the same direction as airflow. Six-factor three-level orthogonal tests were carried out using CFD–DEM coupling simulation to study the influence of the structure and operation parameters of the seed-guiding device on airflow field, seed transport, and seeding performance. The simulation results derived optimal parameters: the depth of the circular section of the seed slide was 2.62 mm, the length of the expansion and contraction section was 188 mm and the length of the contraction section was 20 mm, the seed tube diameter was 19 mm, the airflow velocity was 6.3 m/s, and the rotation speed of the roller was 25 r/min. Under the optimal parameters, the positive pressure required for the seed-guiding device was 256.77 Pa, the time of seeds passing through the seed-guiding device was 0.77 ± 0.02 s, and the velocity of seeds when they came out of the seed tubes was 2.24 ± 0.30 m/s. The qualified rate was 88.33% (2 ± 1 seeds/hill), and the miss-seeding rate was 5.00% (0 seeds/hill). Bench test showed that the qualified rate was 86.80%, and the miss-seeding rate was 6.00%. The seeding performance of the bench test was consistent with the simulation results. Field tests showed that the average number of seedlings per hill was 1.32. The seed-guiding device could meet the requirements of precision hill-seeding for sesame. This study provides a reference for design of a seed-guiding device of a centralized seed-metering device for sesame.

Experimental drought increased the belowground sink strength towards higher topsoil organic carbon stocks in a temperate mature forest

Reduced carbon assimilation by trees is often considered to lower the overall carbon sink function of drought-stressed forests. However, soil organic carbon (SOC) stocks may respond differently to drought than ecosystem carbon flux dynamics, leading to imprecise predictions of soil carbon sequestration when one value is inferred from the other. As a major component of soil organic matter, SOC is the largest actively cycling terrestrial carbon reservoir, and thus fulfills various important ecosystem services. Yet, there is uncertainty about how SOC quantity and quality respond to drought in temperate forests. This study addressed the depth distribution of SOC stocks and soil organic matter stability in a forest exposed to artificial drought for five consecutive growing seasons below clusters of temperate mature deciduous beech (Fagus sylvatica L.) and coniferous spruce (Picea abies (L.) Karst.). In addition to SOC stock determination, we measured concentrations of water-extractable organic carbon (WEOC), performed density fractionation, and determined beta values of SOC (slopes of linear regressions between δ13C of soil and log-transformed SOC content throughout soil depth profiles). Following drought, SOC stocks down to 30 cm depth increased by a factor of 1.5 under P. abies while they did not change with drought under F. sylvatica. Under both species, SOC stocks in the mineral topsoil (0–5 cm soil depth) increased by >80 % with drought, increasing the relative contribution of this thin depth section to total SOC from 5 % to >30 %. At 5–15 cm soil depth, SOC stocks decreased with drought under F. sylvatica but not under P. abies. With drought, carbon in the free light fraction (fLF) increased under F. sylvatica but declined marginally under P. abies. Results from density fractionation and beta values suggest decreased soil organic matter stability under F. sylvatica and increased stability under P. abies. Greater SOC accumulation suggests that the belowground carbon sink strength of drought-stressed forests increases, which contrasts with reduced ecosystem carbon uptake under drought.

Experimental investigation of three-dimensional effects in cavitating flows with time-resolved stereo particle image velocimetry

The present paper is devoted to characterizing the three-dimensional effects in a cavitating flow generated in a venturi-type profile. Experimental measurements based on 2D3C (two-dimensional-three-component) stereoscopic particle image velocimetry are conducted to obtain the three components of the velocity field in multiple vertical planes aligned with the main flow direction, from the center of the channel to the side walls. Time-resolved acquisitions are conducted, so not only time-averaged quantities but also velocity fluctuations can be discussed. The attention was focused on configurations of cloud cavitation, where the attached cavity experiences large-scale periodical oscillations and shedding of clouds of vapor. Although the water channel is purely two-dimensional, some significant flow velocities in the third direction (depth of the test section) were measured. Some of those velocities were found to be related to small differences between the boundary conditions on the two sides, such as minor gaps between the sides and the bottom wall, while others reflect intrinsic three-dimensional mechanisms inside the cavitation area, such as side jets that contribute to the periodical instability process. These mechanisms are discussed, and a possible 3D (three-dimensional) structure of the cavitating flow is proposed.

A study of the dependence of the 3-phase cage motor maximum torque on the centroid of the rotor bar section

The paper investigates the relative influence of the centroid of the three-phase squirrel cage induction motor rotor bar cross section, on the breakdown (maximum) torque of the machine. The influence of the angle of taper, the top width and the radial depth of the bar section, as established design variables, were also investigated so as to properly situate the degree of influence of the centroid, in comparison; as far as the maximum torque is concerned. The machines were investigated in their steady state operating mode using the equivalent circuit method. The machine learning capabilities of the Least Square Support Vector Machine (LSSVM) was deployed to extract by prediction, information about the likely dependencies between the randomized block of the geometric variables and the maximum torque, and the captured information was stored using the Root Mean Square Error (RMSE) of predictions. The validated results show that the rotor leakage reactance – a part determinant of the maximum torque; tends to show some significant sensitivity to a design change in the centroid of the transverse section of the rotor bar.

The precision of the migration image of the depth section on the seismometry observations on northwestern Black Sea shelf

For many years, the Institute of geophysics has been developing original versions of the finite-difference migration and wavefield modeling techniques for a valid reproduction of the geological cross-section. The modeling provides a practical test of the accuracy of the reproduction of various geological structure features on a migration result and a way to define, in the observed field, the waves which can be used to produce a migration image of the geologic environment efficiently.
 In 2013, the Institute conducted a marine seismic investigation with reflection CDP (Common Deep Point) profiles on the continental slope of the NW part of the Black Sea. The registered wavefields were processed using full-wave finite-difference post-stack migration. The efficiency and validity of the processing methods for various geological structures were evaluated with the help of finite-difference modeling of the wavefield based on solving the wave equation on a grid with a seven-point pattern.
 The study validates the precision of marine seismic data processing using full-wave finite-difference post-stack migration with the help of wavefield modeling.

Artificial confocal microscopy for deep label-free imaging.

Widefield microscopy of optically thick specimens typically features reduced contrast due to "spatial crosstalk", in which the signal at each point in the field of view is the result of a superposition from neighbouring points that are simultaneously illuminated. In 1955, Marvin Minsky proposed confocal microscopy as a solution to this problem. Today, laser scanning confocal fluorescence microscopy is broadly used due to its high depth resolution and sensitivity, but comes at the price of photobleaching, chemical, and photo-toxicity. Here, we present artificial confocal microscopy (ACM) to achieve confocal-level depth sectioning, sensitivity, and chemical specificity, on unlabeled specimens, nondestructively. We equipped a commercial laser scanning confocal instrument with a quantitative phase imaging module, which provides optical path-length maps of the specimen in the same field of view as the fluorescence channel. Using pairs of phase and fluorescence images, we trained a convolution neural network to translate the former into the latter. The training to infer a new tag is very practical as the input and ground truth data are intrinsically registered, and the data acquisition is automated. The ACM images present significantly stronger depth sectioning than the input (phase) images, enabling us to recover confocal-like tomographic volumes of microspheres, hippocampal neurons in culture, and 3D liver cancer spheroids. By training on nucleus-specific tags, ACM allows for segmenting individual nuclei within dense spheroids for both cell counting and volume measurements. In summary, ACM can provide quantitative, dynamic data, nondestructively from thick samples, while chemical specificity is recovered computationally.

Geochemical Responses to Natural and Anthropogenic Settings in Salt Lakes Sediments from North-Eastern Romanian Plain

Chemical analysis was performed on sediment core samples collected from three salt lakes, Amara Lake, Caineni Lake, and Movila Miresii Lake, located in the northeast of the Romanian Plain. The concentration of 10 main elements, 6 heavy metals (HMs), 8 rare earth elements (REEs), and 10 trace elements (TEs)-determined using neutron activation analysis (NAA)-showed variability dependent on the depth sections, lake genesis and geochemical characteristics (oxbow, fluvial harbor/liman and loess saucer type). The assessment of pollution indices (contamination factor, pollution load index, geoaccumulation index, and enrichment factor) highlighted low and moderate degrees of contamination for most of the investigated elements. Principal component analysis (PCA) extracted three principal components, explaining 70.33% (Amara Lake), 79.92% (Caineni Lake), and 71.42% (Movila Miresii Lake) of the observed variability. The principal components extracted were assigned to pedological contribution (37.42%-Amara Lake, 55.88%-Caineni Lake, and 15.31%-Movila Miresii Lake), salts depositions (due to the lack of a constant supply of freshwater and through evaporation during dry periods), atmospheric deposition (19.19%-Amara Lake, 13.80%-Caineni Lake, and 10.80%-Movila Miresii Lake), leaching from soil surface/denudation, rock weathering, and mixed anthropogenic input (e.g., agricultural runoff, wastewater discharges) (13.72%-Amara Lake, 10.24%-Caineni Lake, and 45.31%-Movila Miresii Lake).

Laser welding of different pure copper materials under consideration of shielding gas influence and impact on quality relevant surface topographical features

The high demand for electronic products increases the need for high-quality welds of copper. Laser welding can be applied but may result in undesired weld characteristics such as humping or spatter. Process control is needed to identify defective welds in the production line. Surface topographical features can be used to identify different weld characteristics by optical coherence tomography (OCT). The resulting surface topography of a weld can be influenced by process parameters like its material properties or the application of process gas. In this work, we investigate the influence of different pure copper materials and process gas on weld seam surface features for the classification of quality-relevant weld characteristics. First, the resulting changes in weld depth and metallographic cross sections are qualitatively and quantitively characterized for different pure copper materials under the consideration of weld categories such as melt ejection, deep penetration welding, humping, and heat conduction welding with and without the application of shielding gas. Afterward, a qualitative and quantitative analysis of weld surface features is performed for the beforementioned categories under consideration of the copper material and shielding gas. As a result, an influence on the achievable weld depth could be identified for pure copper with residual phosphor content. No significant changes in surface topographical features could be identified for different material properties of copper. The influence of shielding gas and pure copper material is found to be negligible on surface topographical characteristics for process control.