Frontal Surface Research Articles

Cognitive Network Changes After Exposure to Haptic Vibrotactile Trigger Technology: Results From The ENHANCE Study

The conceptual framework of cognitive networks, or cognits, represents a system of working memory, especially long-term memory arrays that are intrinsically designed to attain certain behavioral ends and that are activated by a neural structure. Despite the fact that cognitions can be used in a plethora of systems, current technologies allow manipulations of the central nervous system (CNS) to execute certain sensory and motor functions. Sensation and tactual perception by the skin are an innate mechanism for human survival and represent our adaptive somatosensorial ability to apprehend information via haptics—the active touch for object recognition and perception by higher centers of the brain. The somatosensation, which is identified by a set of channels and receptors sensitive to a variety of stimuli (thermal, tactile, and mechanical), is critical to survival, balance control, cognition, and pain modulation. Cognits are cutting-edge tools and modalities that provide a landscape of theoretical assets, evidencebased experimental protocols, computational intelligence schemes, and direct empirical modalities that facilitate the understanding of the complex functionalities of the human brain. By evaluating neuroimaging data after somatosensory stimulation and collected via electroencephalogram (EEG), cognition response and change can be obtained that allows researchers to gain a better understanding of emerging scientific approaches aimed at understanding human behavioral outcomes. An emerging technology, haptic vibrotactile trigger technology (VTT), incorporates somatosensory patterns in compression sleeves. eSmartr Smart Compression Sleeves (Srysty Holdings Inc., Mississauga, ON, Canada) with VTT and its Cognitive Boost Technology (CBT) pattern is designed to optimize neural communications for improved mindful wellness. This technology has also been incorporated into patches, braces, apparel (socks), wrist bands, and other routes of delivery. Mindful wellness is considered an outcome of somatosensory intervention that modulates the behavioral responses associated with cognitive networks. Currently, there is limited research exploring these modalities, exposing the need to study new technologies and their influence on somatosensory pathways and cognitive networks. The purpose of this IRB-approved study was to explore the effects of forearm VTT stimulation patterns on cognitive networks by comparing a baseline EEG to an EEG after placing a sleeve incorporating VTT on the right or left forearm of adult healthy individuals. Materials and methods: A baseline EEG was recorded over 5 minutes from 19 scalp locations on 20 subjects ranging in age from 17.6 years to 41.9 years (n=7 females, 13 males). The subject’s dominant arm was then fitted with the eSmartr Smart Compression Sleeve for 20 minutes and another 5-minute EEG was recorded. Both the LORETA (Low Resolution Electromagnetic Tomography Analysis) inverse solution and a power spectral analysis of the surface EEG were calculated. Additionally, for 10 distinct networks, the current sources from 88 Brodmann areas were computed. The variables were absolute power and absolute current density in 1 Hz increments in 10 frequency bands (delta, theta, alpha-1, alpha-2, beta-1, beta-2, beta-3, and hi-beta). Paired t-tests were computed for each individual for all EEG parameters, as well as group paired t-tests, between the baseline EEG and followup EEG. Results: The results showed statistically significant t-test differences (P < 0.01) in both the surface EEG and the LORETA current sources between the baseline measurement and the follow-up ‘sleeve-on’ measurement. The largest differences were detected with a prominent downregulation of alpha and beta frequency powers at both the surface EEG and the LORETA current sources with the “sleeve-on,” as compared to baseline. In addition, the maximal effects of the “sleeve-on” condition were in the left frontal and left temporal surface EEGs and on the medial bank of the somatosensory cortex in the range of the alpha frequency. Changes in the default network and attention network were also prominent. Conclusions: Study results indicate that these non-pharmacologic, non-invasive, haptic vibrotactile trigger technology (VTT) patterned compression sleeves elicited a response in multiple cognitive networks. These networks play a key role in executive function, memory, attention, mood, and information flow. There was a prominent effect of the haptic vibrotactile trigger technology with the CBT- patterned sleeves on the EEG that was primarily located in alpha and beta frequency bands. The substantial impacts on the homuncular projection of the arm to the medial somatosensory cortex as well as the default network demonstrated activity influenced by the patterned sleeve. The mechanisms of action of the VTT sleeve on the brain, neuropathways, and the EEG spectrum are still being investigated. If results are confirmed with further research, this novel VTT technology could be a promising addition as a non-invasive and non-drug treatment approach for a variety of conditions and therapeutic applications.

Cortical and subcortical structural differences in psychostimulant-free ADHD youth with and without a family history of bipolar I disorder: a cross-sectional morphometric comparison

Although attention-deficit/hyperactivity disorder (ADHD) and a family history of bipolar I disorder (BD) are associated with increased risk for developing BD, their neuroanatomical substrates remain poorly understood. This study compared cortical and subcortical gray matter morphology in psychostimulant-free ADHD youth with and without a first-degree relative with BD and typically developing healthy controls. ADHD youth (ages 10-18 years) with (‘high-risk’, HR) or without (‘low-risk’, LR) a first-degree relative with BD and healthy comparison youth (HC) were enrolled. High-resolution 3D T1-weighted images were acquired using a Philips 3.0 T MR scanner. The FreeSurfer image analysis suite was used to measure cortical thickness, surface area, and subcortical volumes. A general linear model evaluated group differences in MRI features with age and sex as covariates, and exploratory correlational analyses evaluated associations with symptom ratings. A total of n = 142 youth (mean age: 14.16 ± 2.54 years, 35.9% female) were included in the analysis (HC, n = 48; LR, n = 49; HR, n = 45). The HR group exhibited a more severe symptom profile, including higher mania and dysregulation scores, compared to the LR group. For subcortical volumes, the HR group exhibited smaller bilateral thalamic, hippocampal, and left caudate nucleus volumes compared to both LR and HC, and smaller right caudate nucleus compared with LR. No differences were found between LR and HC groups. For cortical surface area, the HR group exhibited lower parietal and temporal surface area compared with HC and LR, and lower orbitofrontal and superior frontal surface area compared to LR. The HR group exhibited lower left anterior cingulate surface area compared with HC. LR participants exhibited greater right pars opercularis surface area compared with the HC. Some cortical alterations correlated with symptom severity ratings. These findings suggest that ADHD in youth with a BD family history is associated with a more a severe symptom profile and a neuroanatomical phenotype that distinguishes it from ADHD without a BD family history.

Understanding the Importance of Drag Coefficient Assessment for a Deeper Insight into the Hydrodynamic Profile of Swimmers.

The main objective of this study was to confirm that the passive drag coefficient is less dependent on swimming speed than the passive drag, Froude, and Reynolds numbers, even as swimming speed increases. The sample consisted of 12 young proficient non-competitive swimmers (seven males and five females: 20.4 ± 1.9 years). Passive drag was measured with a low-voltage isokinetic engine at 1.2, 1.4, 1.6 and 1.8 m/s. The frontal surface area was measured using digital photogrammetry. Passive drag showed significant differences with a strong effect size over the four towing speeds measured (F = 116.84, p < 0.001, η2 = 0.91) with a quadratic relationship with speed. The Froude and Reynolds numbers had similar trends, but with linear relationships. Conversely, the passive drag coefficient showed non-significant differences across the four towing speeds (F = 3.50, p = 0.062, η2 = 0.33). This strongly suggests that the passive drag coefficient should be the variable of choice for monitoring the hydrodynamic profile of swimmers rather than the absolute value of passive drag.

THE STRUCTURE OF THE ANTERIOR CORNEA EPITHELIUM OF THE SUS SCROFA DOMESTICUS AT THE CRYOPHIXATION

The classic histological picture of the anterior corneal epithelium, known from the results of standard histological techniques and light microscopy of preparations of chemically fixed material, describes the presence of three cell layers: basal - germinative, middle and superficial. On preparations of cryofixed material, another homogeneous layer is identified above the cells of the third layer, which is usually identified as the precorneal tear film, that is, a layer of liquid. Analysis and comparison of known data allows us to identify a scientific problem, which is as follows. The structure of the homogeneous layer has not been previously studied, its structure is unknown, therefore, the identification of the homogeneous layer with the precorneal tear film is not justified. We assume that the histological picture of the anterior epithelium on preparations of chemically fixed material is incomplete, and the homogeneous layer is a structural component of the anterior epithelium. Purpose of the study: the structure of the anterior epithelium and homogeneous layer on preparations of cryofixed material. The material for the study was preparations of the eyes of the domestic pig Sus scrofa domesticus, the research method was light microscopy. As a result of the study, it was established for the first time that the homogeneous layer is a structural component of the anterior corneal epithelium. Between the homogeneous layer and the layer of flat cells of the anterior epithelium, another layer is determined in the form of a microscopically detectable thin strip. Taking into account the established fact, it should be concluded that the anterior epithelium of the cornea consists of five layers. The cells in the layers are in a compacted state, the degree of which increases from the basement membrane to the frontal surface of the epithelium, reaching a maximum at the level of the homogeneous layer. The cells of the surface layer are anucleate, filled with an oxyphilic mass, presumably keratin, which indicates the process of keratinization of epithelial cells. The results of the study confirmed the assumption that the histological picture on preparations of chemically fixed material is incomplete. The identification of a homogeneous layer with the precorneal tear film is unfounded.

A high sensitivity microbeam RBS setup for heavy elements implantation profiles analysis

This work presents a new setup that integrates heavy ion RBS with microbeam technology combined with high detection solid angle for the measurement of the depth profile and areal distribution of heavy elements in silicon using a Si microbeam. Focussed 2.4 MeV Si2+ ions were scanned over the frontal or lateral surface of silicon wafers to measure both the areal concentrations and depth profiles of all elements heavier than silicon. Tests were done on samples with Pt concentration range of 4 × 10 12–2 × 10 14 at/cm 3 that was diffused via the Pt-Silicide surface layer process from one lateral surface into the 400 µm thick Si wafers. It is important to note that employing a Si ion beam instead of the conventional He ion beam serves the purpose of not only increasing the backscattering cross section, as in well-established heavy element RBS, but also reducing pileup by eliminating scattering from the Si substrate, which is essential for sensitive analysis. This allows a significant increase in microbeam currents without increasing the count rate in large area detectors. A set of two large area PIN diodes (10x10 mm) were used in an optimized configuration resulting in 1,04 sr detection solid angle. Additionally, an appropriate microbeam collimator was used to shield the PIN diodes from events caused by forward scattering and scattering of the Si ion beam halo from different components in the reaction chamber. Lateral scans of the silicon wafer were performed by focussed Si ions, with ∼10 µm spot size and of the nA range beam currents. The RBS intensity maps containing the Pt depth profile were obtained with a sensitivity of 6.7 × 109 at/cm2.

Development and sexual dimorphism of branchiae in Streblospio benedicti

AbstractThe Spionidae is one of the largest and most studied annelid families, but to date, the development and differentiation of post‐metamorphic anatomy have not been documented. This study used scanning electron microscopy to examine the development of the branchiae, presumed respiratory organs, in Streblospio benedicti. Branchiae in this species are prominent, paired head structures and first appear around the time of metamorphosis, but do not complete their development until the worm reaches the older juvenile or adult stages. We observed that as the branchiae grew, their overall morphology changed through four different shapes: small bud, tubular, tapered, and, finally, bilimbate. In addition, the abfrontal and frontal surfaces each possessed a unique set of cilia patterns, which we named, and these arose in a particular sequence between the 8‐ and 35‐chaetiger stages. This detailed examination of every stage of branchial development led us to discover that branchia in Streblospio benedicti was a sexually dimorphic organ. Streblospio benedicti is one of approximately eight Spionidae in which there is any type of structural sexual dimorphism, and it is the only species in which sexually dimorphic branchiae are found. The male's frontal surface had four unique cilia patterns, and we hypothesize that those located around the medial protrusion capture and control the release of the spermatophores. This first documentation of a spionid's branchial developmental sequence revealed that not only is this respiratory organ involved in reproduction, but it significantly differentiates after metamorphosis through adulthood.

The Physical Properties of Arabica and Robusta Coffee Beans from Temanggung and Lampung

The development of processes and handling techniques, packing, and transportation of coffee beans all benefit from knowledge of the physical attributes of coffee beans. This research was done to describe the physical characteristics of green and roasted Temanggung and Lampung coffee beans. The findings revealed that Robusta roasted beans from Lampung with a moisture content of 1.70% had the highest values of bean dimensions, geometric mean diameter, arithmetic mean diameter, equivalent mean diameter, frontal surface area, surface area, and volume. Arabica green beans from Lampung and Temanggung had the highest shape index and density values, whereas Arabica roasted beans from Lampung had the highest aspect ratio and sphericity values. Arabica green beans from Temanggung and Arabica roasted beans from Lampung had moisture contents of 6.46% and 2.69%, respectively. Meanwhile, Robusta green beans from Lampung had the greatest scores for mass and porosity. To offer somewhat full information on the design factors involved in the roasting profile of a coffee roaster, other engineering properties should be investigated in future studies.

Development of specialized disk emitters for the formation of high-intensity ultrasonic fields in gaseous media

The article presents various types of emitter designs and schemes of emitting surfaces for the formation of ultrasonic fields with different characteristics and directivity. 4 types of emitters have been developed and their main characteristics have been determined. It has been established that a radiator with a flat frontal surface provides 167 dB and makes it possible to intensify a number of technological processes in the near zone (up to 1 meter), such as coagulation and drying. An emitter with a step-variable surface and predominant radiation of one phase of oscillations makes it possible to create a homogeneous ultrasonic field in the air at a sound pressure level of 155-157 dB at a distance of up to 2 meters to the emitter. Focusing radiators allow to provide sound pressure level up to 173 - 177 dB in the focus (at a distance of 0.3 m), while in the far zone the intensity drops significantly (up to 145-150 dB).

Diurnal Characteristics of Heavy Precipitation Events under Different Synoptic Circulation Patterns in the Middle and Lower Reaches of the Yangtze River in Summer

Aiming at the rainstorm days (≥50 mm/d) in the middle and lower reaches of the Yangtze River during 2010–2020, the obliquely rotated principal component in T-mode (PCT) method is used to classify the daily mean 850 hPa geopotential height, including Type 1 (vortex/shear line), Type 2 (frontal surface), Type 3 (warm shear line), Type 4 (warm inverse trough line), Type 5 (typhoon-westerly trough), and Type 6 (easterly wave). We studied the weather system configurations of different synoptic circulation patterns, their long-term trends, and their impacts on diurnal variations of heavy precipitation and drew the following conclusions: Type 1, Type 2, or Type 3 shows balanced double-peak frequencies of the start time of heavy precipitation during 06:00–08:00 BT and around 17:00 BT, respectively. For Type 1, dynamical lifting and thermal lifting play balanced roles, while for Type 2 and Type 3, dynamical lifting plays a key role. The number of rainstorm stations for Type 1 shows a slight increasing trend, while that for Type 2 or Type 3 shows a significant increasing trend. Type 4, Type 5, or Type 6 show a significant single peak frequency of the start time during 15:00–16:00. Type 5 and Type 6 are mainly affected by dynamical lifting along with favorable cape values, which can trigger rainstorms. The number of rainstorm stations for Type 4 or Type 6 shows a decreasing trend (that for Type 4 is more significant), while that for Type 5 shows a slightly increasing trend.

SIMULATION OF INTERACTION OF WAVES WITH THE PROTECTIVE DAM OF THE DANUBE – BLACK SEA MARINE CHANNEL

Ensuring uninterrupted navigation on the Danube River and the shortest exit to the Black Sea is a priority direction for the implementation of the seventh international transport corridor, which unites the countries of Europe and Asia. For this purpose, the protection dam of the Marine channel of the Danube-Black Sea deep-sea passage was built, which was partially destroyed by storm waves and ice load. This made it necessary to carry out scientific researches in order to strengthen the operational stability of the dam and ensure its effective use. The paper presents the results of numerical and physical simulation of the interaction of waves with the protective dam of the Marine channel of the Danube-Black Sea and loads on the dam structure. Mathematical simulation was performed using the SWAN refraction and spectral model, as well as the XBeach model. Experimental research was carried out in laboratory conditions in a wave channel. The estimated distribution of the wave field near the dam under storm surge conditions was obtained and the space-time characteristics of wave pressure fluctuations on the streamlined surface of the protective dam model were determined. Integral and spectral characteristics of the pressure fluctuation field were obtained and a multi-stage form of a dam with two berms was proposed, which significantly reduced the wave load and was resistant to storm waves. The berms performed the functions of underwater breakwaters and significantly reduced the energy of the wave impact on the upper part of the dam. The optimal shape of the dam and the geometric parameters of its frontal surface were determined. It is proposed to build the seaward part of the protective dam under natural conditions with the following parameters: a lower deep-water slope with a slope of 1 : 1,5, then at a depth of 4 m a lower berm with a width of 10 m. Then make a slope with a slope of 1 : 5, and then at a depth of 2 m to install an upper berm with a width of 10 m. It is recommended to finish the protective dam of the Marine channel of the Danube-Black Sea deep-sea passage with a ridge with a slope of 1 : (3 – 3,5). The facing of the frontal part of the dam should be made of stone overburden with stones of fraction 1,2 m.

Элементы визуализации при обследовании опасных производственных объектов с использованием беспилотного летательного аппарата

The paper considers the possibility of using visualization when preparing a task for frontal surface examination of hazardous industrial facilities using unmanned aerial vehicles. The research is based on the results of an experimental survey of buildings and structures of a large metallurgical enterprise in Russia. As initial data, photographs of buildings and structures obtained using a camera of an unmanned aerial vehicle and their drawings were used. When building a 3D model, the capabilities of Autodesk AutoCAD and Autodesk Revit were used. When building a 2D information model, a combination of a 3D model and a photograph of the object was used. The resulting 3D and 2D models are included in the structure of the flight chart as part of an applied digital platform in an automated decision-making system for expert assessment of the technical condition compliance of a hazardous production facility with regulatory requirements. Violation of regulatory requirements entails the occurrence of emergencies and incidents at an industrial enterprise. Visualization elements allow increasing the reliability of information entering the database of expert information.

Finished and unfinished rhythm in architectural composition

The rhythm was at all times and in all forms of art. Already in the countries of the Ancient East the composition was ordered, distinguished by strictness, the presence of rhythm. In ancient Egyptian and Greek art rhythm was also the main form of composition.&#x0D; In the Renaissance rhythm was considered one of the three main tasks of composition. Knowledge about rhythm as an integral compositional means is constantly expanding, especially after the first theoretical works on architectural composition. Rhythm is an even alternation of ordered elements and is considered one of the most influential means of creating a coherent architectural composition.&#x0D; Rhythmic (metrical) order as a regularity can develop endlessly, but in an artistic composition, where integrity and unity of form are an integral attribute, repetition must have certain limits, a series must have a limited length and have a beginning and an end. In this connection a number of creative problems arise when using rhythm in specific architectural compositions of the frontal surface. It is necessary to notice the peculiarity of the combination of three elements in the composition – if there is a clearly expressed axis, then the ternary rhythm (the one consisting of only 3 elements) is considered complete, if there are elements built according to an increasing or decreasing vector, then this type of ternary rhythm must be completed by methods of stopping the rhythm. On the frontal architectural plane the rhythm can appear in an unstoppable form when the idea of the work consists in bringing the viewer's thought out of the compositional field – an opportunity to have own thoughts about the work, to get the answers outside the creation. In this case the rhythm really does not stop visually. In order for such frontal compositions to feel complete the elements of the rhythmic series and the composition in general must be carefully proportioned, or the stop of the rhythm must be manifested by the natural boundaries of the form which is not visible visually but sensuously encompasses the rhythmic series. The finished rhythm can be achieved by the main ways of stopping it in the composition: form, "extreme element", "rhythm – counter rhythm", stopping the vertical rhythm with a horizontal one. The use of methods of stopping the rhythm in compositional practice simplifies the creation of a complete composition.

Numerical study of discrete film cooling near the rudder shaft of a hypersonic air fin model

Rudder shaft, connecting the air fin to the fuselage of hypersonic vehicles through the mounting gap, is subject to intense aerodynamic heating, necessitating thermal protection techniques. Film cooling is a promising technology to mitigate this heating, but its thermal protection performance on the rudder shaft, as well as aerothermal mechanisms behind major design parameters, is still unexploited. This paper conducts numerical simulations to evaluate thermal protection performance of discrete film cooling applied to the rudder shaft of an air fin in hypersonic flow. Three discrete cooling holes are arranged on the flat plate upstream of the rudder shaft. Parametric studies are then executed to investigate the effect of cooling hole locations and coolant injection angles on thermal protection performance of the rudder shaft. k-ω SST model is used to solve the Reynolds-Averaged Navier-Stokes equations, and perfect gas without chemical reaction is adopted. Total pressure of the freestream is set as 0.6 MPa, while that of the coolant is fixed at 12000 Pa. The freestream has a Mach number of 6 and unit Reynolds number is 7.65 × 106/m. It is found that discrete film cooling can provide excellent thermal protection performance on the rudder shaft by consuming a coolant of 1.41 × 10−4 kg/s. For vertically-injected coolant, thermal protection performance deteriorates as the cooling holes are placed further upstream of the rudder shaft and the distribution of coolant alters qualitatively from a concentrated pattern to a segregated one due to the lower local blowing ratio. If the location of cooling holes is fixed, as the injection angle of coolant decreases, the impingement point of the cooling jet changes from the bottom of air fin to the frontal surface of rudder shaft, and more coolant is attached to the flat plate at the gap bottom.

Agreement between Different Methods to Measure the Active Drag Coefficient in Front-Crawl Swimming.

The aim of this study was to analyze the agreement of the active drag coefficient measured through drag and propulsion methods. The sample was composed of 18 swimmers (nine boys: 15.9 ± 0.9 years; nine girls: 15.3 ± 1.2 years) recruited from a national swimming team. The velocity perturbation method was used as the drag measurement system and the Aquanex system as the propulsion system. For both sexes combined, the frontal surface area was 0.1128 ± 0.016 m2, swim velocity 1.54 ± 0.13 m.s-1, active drag 62.81 ± 11.37 N, propulsion 68.81 ± 12.41 N. The level of the active drag coefficient agreement was calculated based on the mean values comparison, simple linear regression, and Bland Altman plots. The mean data comparison revealed non-significant differences (p > 0.05) between methods to measure the active drag coefficient. Both the linear regression (R2 = 0.82, p < 0.001) and Bland Altman plots revealed a very high agreement. The active drag coefficient should be the main outcome used in the interpretation of the swimmers' hydrodynamic profile, because it is less sensitive to swimming velocity. Coaches and researchers should be aware that the active drag coefficient can also be calculated based on propulsion methods and not just based on drag methods. Thus, the swimming community can now use different equipment to measure the hydrodynamics of their swimmers.

Computational analysis of passive strategies to reduce thermal stresses in vertical tubular solar receivers for safety direct steam generation

When exposed to high non-uniform heat fluxes on the receiving surface, significant temperature gradients develop in the tubes, producing thermal stress and deformations in the receivers. This paper reports a detailed investigation of the thermal and structural performance of a solar tower system that operates with direct steam generation tubes when the fins are added to the internal surface and thickness varies. Six tubes were evaluated, two without fins varying the wall thickness (5 mm and 3 mm) and four with fins under different configurations. The thermal system corresponds to a representative tube of an external tubular receiver of a central tower system. The thermal receiver operates with direct steam generation under a non-uniform concentrated solar flux with a maximum value of 0.93 MW/m2. The best configuration of the tube was with fins on the frontal surface of the tube, maintaining a receiving wall thickness of 3 mm and an adiabatic wall thickness of 5 mm. It could reduce maximum thermal gradients and temperature by 31% and 14%, respectively, maximum thermal stresses by 38%, and maintain vapor mass flow at the output (276 kg/h).

Effects of sheltering on the unsteady wake dynamics of tandem cylinders mounted in a turbulent boundary layer

The unsteady wake dynamics of two finite wall-mounted cylinders of unequal height and arranged in tandem are investigated using time-resolved particle image velocimetry (TR-PIV). The cylinders were fully submerged in a turbulent boundary layer with a Reynolds number based on the cylinder diameter (d) of 5540 and boundary layer thickness of$\delta /d = 8.7$. The centre-to-centre spacing between the cylinders was fixed at 4d. The degree of sheltering was studied by varying the height of the upstream cylinder (UC)$(h/d \in [0.7\unicode{x2013} 7.0])$while keeping the height of the downstream cylinder (DC) constant at$H/d\; = \; 7.0$. The resulting height ratios were$h/H = 0.10,0.25,0.50,0.75$and$1.00$denoted as HR10, HR25, HR50, HR75 and HR100, respectively. The wake dynamics of the DC were also compared to those of an isolated single cylinder (SC) with similar Reynolds number, aspect ratio and submergence ratio. TR-PIV measurements were performed in the symmetry plane for all test cases and five spanwise planes along the height of HR75. The results showed that as the height ratio increases, the downwash from the free end of the UC impinges directly on the frontal surface of the DC and induces a strong upwash on the opposite rear side of the DC. The induced upwash impedes the downwash from the free end of the DC much earlier than observed behind the SC, resulting in a reduced reverse flow area and high velocity deficit in the sheltered portion of the DC. Nonetheless, the reverse flow area behind the UC and DC undergoes a quasi-periodic pumping motion with frequencies that are synchronized for HR25 to HR100. Spectral analysis and proper orthogonal decomposition also reveal that the attachment of the shear layers of the UC on the DC also promotes a lock-in anti-symmetric vortex shedding behaviour.

Steady three-dimensional unbounded flow past an obstacle continuously deviating from a sphere to a cube

We perform three-dimensional particle resolved direct numerical simulations of the flow past a non-spherical obstacle by a Finite Volume cut-cell method, a sub-class of non-body-conforming methods that provides a sharp description of the boundary, which is strictly mass and momentum conservative and can be easily extended to adaptive grids. The present research work discusses the effect of corner rounding and the incidence angle for a range of Reynolds numbers for which the flow exhibits a steady-state behavior. The obstacle is placed in a large cubic domain that properly models an unbounded domain. Hierarchically refined Cartesian meshes are used where the obstacle resides at the finest level of the mesh hierarchy, thus ensuring that the resolution of the boundary layer and the wake of the obstacle is highly accurate, along with significantly reducing the number of grid cells and the computing time. Specifically, we characterize the drag force and the main features of the flow past a bluff obstacle transitioning in shape from spherical to cuboidal through a superquadric geometrical representation. A superquadric representation is suitable for our study since it preserves geometric isometry, and our analysis, thus, focusses on non-sphericity caused by the level of curvature. We investigate a range of Re from 10 to 150, which spans the flow from attached to symmetric and separated past five different obstacle shapes, with the corner radius of the curvature of r/a=2/ζi=1,2/2.5,2/4,2/8 and 0 placed at incidence angles of α=0°, 15°, 30°, and 45° with respect to the streamwise direction. In general, our results show that the obstacle bluffness increases with α and ζi and this increase is more prominent at higher Re. Higher drag forces are a consequence of either higher viscous forces for more streamlined bodies and in less inertial regimes or higher pressure forces for more bluff bodies and in highly inertial regimes, depending on how the corners are contributing to the frontal and lateral surface areas.

Numerical Study of Percolation and Seepage Behaviors in Ion‐Adsorption‐Type Rare Earth Ore Leaching Process

Ionic rare earth ore is a type of featured rare earth ore in China. Its mining process suffers from a long leaching cycle and considerable consumption of leaching agents. Improving mining efficiency requires a sound physical understanding of the leaching process. In this study, the CFD‐based numerical model is used to analyze the physical process of leaching through porous media formed by particles. The simulation results indicate that a lower packing porosity and smaller particles packed granular porous medium result in much larger energy dissipation during seepage, and the energy dissipation increases with seepage velocity. It is found that when the seepage velocity increases to a certain high value, the energy dissipation exceeds the value predicted by Darcy’s law, which is mainly caused by liquid turbulence. Additionally, the effect of particle shape is examined. The results show that the granular medium composed of prolate particles causes larger energy dissipation than oblate particles, and spherical particles play the least role. This phenomenon may result from the particle shape affecting the area of the frontal contact surface between particles and liquid. The results provide new insights into the fundamental understanding of percolation and seepage behaviors in the ion‐adsorption‐type rare earth ore leaching process.

An experimental study of dynamic icing process on an Aluminum-Conductor-Steel-Reinforced power cable with twisted outer strands

An experimental campaign was conducted to investigate the dynamic icing process on an Aluminum-Conductor-Steel-Reinforced (ACSR) power cable with twisted outer strands and characterize the resultant wind loads experienced by the power cable under both dry rime and wet glaze icing conditions. In addition to recording the dynamic icing process over the cable surface with a high-resolution imaging system, the three-dimensional (3D) shapes of the ice layers accreted on the cable model were also quantified by using a novel 3D profile scanning system. While the evolution of the wake flow behind the iced ACSR cable was quantified with a Particle Image Velocimetry (PIV) system, the variation of the wind loads experienced by the cable model was also examined based on the measurements of force/moment transducers. Under the dry rime icing condition, opaque, grainy ice was found to accrete only within the impinging zone of airborne water droplets over the cable frontal surface without any noticeable water runback flow over the cable surface. In comparison, substantial unfrozen water was observed to run back over the cable surface under the wet glaze icing condition, causing the formation of transparent, glazy ice layer over a much wider area over the cable surface. Correlating with the formation of more complicated glazy ice humps/horns over the ACSR cable surface, the accumulated ice mass was found to grow much faster during glaze icing process, in comparison to that of rime icing case. While the resultant wind loads acting on the iced ACSR cable was found to decrease gradually with the increasing icing time under the rime icing condition, the corresponding values were found to increase continuously under the glaze icing condition.

Blade optimal design parameters determination

Introduction. In Kazakhstan in present time there is a large number of earthmoving works, which leads to an increase in the demand for earthmoving-transport machines (ETM), in particular bulldozers of different types. In various industries and construction projects, the fleet of foreign-made ETM is operated and constantly updated, including the CIS countries (Russia, Belarus, Ukraine, etc.) in various type-sizes. So at construction sites, including the construction of roads and railways, bulldozers are widely used: Caterpillar Corporation such as Cat (USA), Liebheer (Germany), Xuanhua Construction machinery Co, Ltd (HBXG) and ZoomLion and Shehwa (China); bulldozers ChTZ-UralTRAK (Russia), etc.The construction of roads and railways with a length of several thousand kilometers is impossible to imagine without the participation of a universal bulldozer. One of the most important components of the bulldozer is the working organ (WO) of the bulldozer.The performance of the bulldozer largely depends on what type of blade is installed on it. Capacity (maximum prism of drawing the soil) is one of the main characteristics determined by the height and width of the blade, and most manufacturers offer add-ons (visor) that makes it possible to increase the height of the blade. Increasing the blade height allows more material to be moved and reduces spillage through the top of the blade. On the other hand, increasing the volume of the drawing prism along the width of the blade is offered by the side cheeks, giving the blade the shape of a bucket. They do not allow the moving soil to fall out on the sides of the blade (side rollers), thereby increasing the volume of material being moved. However, an excessive increase in blade capacity will require additional power costs of the bulldozer during operation, which will cause an increase in loads on the machine components and accelerate the intensity of their wear, especially when the bulldozer moves up the slope.The volume of material moved by the blade in one pass depends, in addition, on the possibility of changing the angle of the blade relative to the vertical and horizontal plane. In modern blade designs, the positions of the angle of inclination are regulated by 4 or 6 positions, depending on the category of soil being developed. The purpose of this study is to optimize the geometric parameters and establish the trapezoidal shape of the blade, taking into account the interaction of its frontal surface with the formed maximum prism of drawing the soil.Materials and methods. As materials, the developed soil and the bulldozer blade were used, the process of their interaction was investigated with the maximum formation of the prism of drawing the soil before the dump, using the graphic-analytical method of research.Results. The process of interaction of the blade with the soil has been optimized by graphic-analytical means, the maximum (maximum permissible) parameters of the blade have been determined, taking into account the traction factor of the bulldozer and the category of the soil being developed.Discussion and conclusion. Until now, the geometric shapes of promising designs of the bulldozer blade were installed mainly by experimental means, without taking into account the contact of the blade area with the ground. Methods for determining the rational shape of the blade have not been developed, especially the theoretically grounded optimal parameters of the WO, taking into account the touch of the longitudinal section of the soil from the frontal surface of the blade. Methods for determining the optimal (adapted) shapes and geometric parameters of the WO were not developed, taking into account the contact of the frontal surface of the blade with the maximum drawing prism. Methods for calculating the optimal parameters of the perspective blade design adapted to the developed soil are proposed:– rational geometric shapes of both the frontal and cross-section of the blade are determined;– mathematical formulas for determining the optimal parameters of the new blade design are presented, namely:the height of the blade and the visor; width of the blade, visor and additional knife-extender;– defined: the perimeter of the blade, the width and height of the side roller, when forming the maximum prism of drawing the soil in front of the blade.