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Even though beam-type elements are widely adopted in the industry due to their low computational cost and potential time savings when modeling, they present a significant shortcoming given by their own formulation, which makes them incapable of accounting for local joint topology, which has a notable influence on the behavior of these structures. In this scenario, solutions that can mitigate this drawback while still providing improved results with simple models are of special interest. Many research works have focused on joint-specific approaches, as reflected in the literature. This paper introduces a novel generally improved beam model. This model uniquely features 4 nodes, 12 elastic elements, and 1 beam, contrasting starkly with the conventional beam elements that consist of merely 2 nodes and 1 element. This innovative model enhances the adaptability of modeled structures at the joint level. Crucially, it necessitates a methodology for the precise estimation of the elastic elements at the joint level. This article explores the capabilities of artificial neural networks for predicting the stiffness values derived from the calculated displacements at specific points within a complete structure. This research provides a complete analysis of the proposed methodology showing the significant limitations encountered for ANN when predicting finite element methodology (FEM)-derived values. The results and findings obtained in the article serve as a valuable reference paving the way for future studies involving finite element models and artificial neural networks. [ABSTRACT FROM AUTHOR]

Amodal completion involves the impression of existence and properties of visually occluded parts of objects. One aspect of this phenomenon that has been somewhat neglected is the amodal completion of color, which involves the impression that amodally completed surfaces have a particular color. In this paper, this aspect is investigated by constructing a large number of displays with identical target figures embedded in systematically varying contexts, to find out which contexts are conducive for amodal completion of color and which are not. In this setup, the main effects of changes of contexts are changes of geometric and photometric features of junctions along the borders of the target regions, which can cause dramatic differences in the appearance of those regions. Generally, a certain arrangement of T-junctions supports the impression of amodal completion of color, and it can be argued that certain types of X-junctions support a variant of this effect as well.

It is commonly acknowledged that the human factor and the interaction between the human factor and the road environment are among the most common causes of road accidents. Physiological signals can provide a real-time assessment of the driver's state because they can be collected continuously without interfering with the driver's task performance or the drivers' perception of the road. This study presents a method for measuring and quantifying drivers' physiological responses when approaching T-junctions and roundabouts using electrodermal activity and speed variations. Speed and electrodermal activity were collected continuously during a driving study which took place on a test environment based at Cranfield University and surrounding roads. Twenty participants were involved in the study. The analysis focused on four crossing manoeuvres on two T-junctions and a roundabout. The association Rule with the Apriori algorithm was used in order to evaluate associations between the variables related to electrodermal activity, i.e. the number and amplitude of the SCR peaks (assessed by the Electrodermal Impact Index in aggregate form), and the variables related to speed, i.e. the speed variation and its sign (positive or negative), for each type of intersection. The main results of this study can be summarized as follows: 1) the rules obtained for the manoeuvres on the T-Junctions show that the T-junctions induce low variations in the electrodermal activity and are often associated with a significant speed increase (between 20% and 30%); 2) the rules obtained for the manoeuvres on the roundabout highlights that the roundabout induces high variations in the electrodermal activity and is associated with a significant speed reduction (between 20% and 40%).

It is commonly acknowledged that the human factor and the interaction between the human factor and the road environment are among the most common causes of road accidents. Physiological signals can provide a real-time assessment of the driver's state because they can be collected continuously without interfering with the driver's task performance or the drivers' perception of the road. This study presents a method for measuring and quantifying drivers' physiological responses when approaching T-junctions and roundabouts using electrodermal activity and speed variations. Speed and electrodermal activity were collected continuously during a driving study which took place on a test environment based at Cranfield University and surrounding roads. Twenty participants were involved in the study. The analysis focused on four crossing manoeuvres on two T-junctions and a roundabout. The association Rule with the Apriori algorithm was used in order to evaluate associations between the variables related to electrodermal activity, i.e. the number and amplitude of the SCR peaks (assessed by the Electrodermal Impact Index in aggregate form), and the variables related to speed, i.e. the speed variation and its sign (positive or negative), for each type of intersection. The main results of this study can be summarized as follows: 1) the rules obtained for the manoeuvres on the T-Junctions show that the T-junctions induce low variations in the electrodermal activity and are often associated with a significant speed increase (between 20% and 30%); 2) the rules obtained for the manoeuvres on the roundabout highlights that the roundabout induces high variations in the electrodermal activity and is associated with a significant speed reduction (between 20% and 40%). • The interaction between human factor and road environment is among the most common causes of road accidents. • Physiological signals are a useful metric for providing feedback about a driver's state; • This study presents a method for quantifying drivers' physiological responses when approaching T-junctions and roundabouts. • The Apriori algorithm was used to evaluate associations between the variations of electrodermal activity and speed. [ABSTRACT FROM AUTHOR]

Acoustic resonances in internal flows can cause noise, vibration, and even equipment damage. One geometry prone to acoustic resonance is a deadleg at the point where the main flow turns into a side branch. Here, we report experimental and computational fluid dynamics (CFD) studies of flow-generated pulsation in such a geometry over a wide range of mean flow velocities. Experimental results of the normalized pulsation pressure amplitudes (P*) versus Strouhal number characterized the flow–acoustic field for acoustically tuned and detuned systems and for branch to main pipe diameter ratio of 1.0. The unsteady CFD simulations revealed the characteristic volume integral of the cross-product of the vorticity field and the velocity field (ω×U) in the vicinity of the T-junction which helped in quantifying the acoustic source power for different conditions. In addition, the cross-product (ω×U) in the direction along the main line is almost exactly out of phase with the acoustic velocity at the T-junction. The pressure amplitude at the closed end of the deadleg reaches maximum when two conditions are met: (i) the system overall acoustic resonance frequency matches closely the frequency of the oscillating component of the cross-product (ω×U) characterized by a Strouhal number and (ii) the deadleg length is tuned to an odd number of ¼ wavelength of this frequency such that maximum acoustic velocity is reached at the T-junction. Synchronized images generated from the unsteady CFD simulations revealed valuable insight into the velocity and vorticity field in the region of the T-junction in support of Howe's acoustic source power equation. [ABSTRACT FROM AUTHOR]

Relevance of the research is determined by the need to analyze the features of the workflow in machines with junctions of arbitrary geometry, combining/separating the flows of viscous media, in order to accurately and carefully predict the contingencies of their functioning due to the expressed thermal and dynamic loads caused by the effects of separation, detachment, pressure, the evolution of the structure of complex, shear, non-isothermal internal flows when at contact with the wall; reasonable choice, taking into account the possibilities of modern computing technology, the most natural approach of studying the spatial and unsteady nature of flows in these technical systems. The aim of this paper is to understand the problems of the modern level of research of flows in T-shaped channels, which are one of the main elements of technical equipment in the oil and gas industry; to establish the value of the existing results of experimental and theoretical analysis of complex shear flows in order to improve methods that contribute to an increase in the operational and structural level of the devices under high dynamic and thermal loads; to define the data for verification of models capable of more reliably predicting features of currents and heat and mass transfer in pipes; to give recommendations to the practice of calculating reliability of devices with T-shaped sections. Methodology: complex theoretical and experimental methods of analysis of hydrodynamics and heat and mass transfer at viscous-inertial laminar and turbulent flows of hydrocarbon drop and gaseous viscous media in internal systems with T-connections of the main and branch pipe. Results. The authors have carried out a critical review of modern data, modeling methods and models of studies of hydrodynamics and heat exchange processes when mixing drip and gaseous flows in elements of pipeline networks in a wide range of changes in mode and geometric parameters (T-connections, symmetrical/asymmetric expansion, Re=102…107, M

DNA self‐assembly allows the construction of nanometre‐scale structures and devices. Structures with thousands of unique components are routinely assembled in good yield. Experimental progress has been rapid, based largely on empirical design rules. Herein, we demonstrate a DNA origami technique designed as a model system with which to explore the mechanism of assembly. The origami fold is controlled through single‐stranded loops embedded in a double‐stranded DNA template and is programmed by a set of double‐stranded linkers that specify pairwise interactions between loop sequences. Assembly is via T‐junctions formed by hybridization of single‐stranded overhangs on the linkers with the loops. The sequence of loops on the template and the set of interaction rules embodied in the linkers can be reconfigured with ease. We show that a set of just two interaction rules can be used to assemble simple T‐junction origami motifs and that assembly can be performed at room temperature. [ABSTRACT FROM AUTHOR]

• Drivers showed poor detection of motorcycles compared to cars at far distances. • Short-term cognitive conspicuity training did not increase driver detection of approaching motorcycles. • Training slowed driver responses to detecting approaching cars. A common cause of road accidents is driver failure to perceive an approaching motorcycle. In a lab-based study, we investigated whether a simple naturalistic training intervention designed to increase the cognitive conspicuity of motorcycles could improve drivers' recognition of approaching motorcycles. Experienced drivers completed a series of motorcycle search tasks (training condition) or passively viewed scenes from nature (control) prior to performing a vehicle recognition task from the perspective of a driver approaching a T-junction. Results confirm established findings that drivers perform poorly at recognising motorcycles compared to cars, especially at far distances. However, motorcycle search training had no effect on driver accuracy in recognising approaching vehicles. Training lead to increased response times for recognising approaching cars relative to motorcycles, which could suggest a more thorough consideration of the road scene following training. We conclude that using motorcycle search training to raise the cognitive conspicuity of motorcycles is not effective in increasing their detection from a single delivery of training. Focusing on increasing motorcyclist visibility may be a more effective way to improve driver responses to motorcycles at junctions. [ABSTRACT FROM AUTHOR]

The actual behavior of welded T-junctions in tubular structures depends strongly on the topology of the junction at the joint level. In finite element analysis, beam-type elements are usually employed due to their simplicity and low computational cost, even though they cannot reproduce the joints topologies and characteristics. To adjust their behavior to a more realistic situation, elastic elements can be introduced at the joint level, whose characteristics must be determined through costly validations. This paper studies the optimization and implementation of the validation data, through the creation of an optimal surrogate model based on neural networks, leading to a model that predicts the stiffness of elastic elements, introduced at the joint level based on available data. The paper focuses on how the neural network should be chosen, when training data is very limited and, more importantly, which of the available data should be used for training and which for verification. The methodology used is based on a Monte Carlo analysis that allows an exhaustive study of both the network parameters and the distribution and choice of the limited data in the training set to optimize its performance. The results obtained indicate that the use of neural networks without a careful methodology in this type of problems could lead to inaccurate results. It is also shown that a conscientious choice of training data, among the data available in the problem of choice of elastic parameters for T-junctions in finite elements, is fundamental to achieve functional surrogate models.

The merging of pedestrian streams is a common phenomenon in pedestrian traffic and evacuation. However it is prone to stampede and can cause immense human and economic damage because of the unreasonable merging strategy. This paper establishes a bidirectional pedestrian flow merging model based on social force model to study the effect of the ratio of the branch inflow to the total inflow on evacuation efficiency of pedestrian merging at a T-junction. The moving characteristics of pedestrian, pedestrian average speed and maximum value of density in different ratios were acquired. The most favorable ratio for evacuation was obtained by the thorough analysis. The results of this work can provide some references for controlling the merging of pedestrian streams at T-junctions during evacuation, and is contribute to propose some related controls and optimization measures to ease the congestion causing by merging, thereby increasing the evacuation efficiency. [ABSTRACT FROM AUTHOR]

T-junctions occur where surface strips start or terminate. This paper develops a new way to create smooth piecewise polynomial free-form spline surfaces from quad-meshes that include T-junctions. All mesh nodes are interpreted as control points of GT-splines, that is, geometrically smoothly joined piecewise polynomials. GT-splines are akin to and compatible with B-splines and cover simple T-junctions by two polynomial pieces of degree bi-4 and more complex ones by four such patches. They complement multi-sided surface constructions in generating free-form surfaces with adaptive layout. Since GT-splines do not require a global coordination of knot intervals, GT-constructions are easy to deploy and can provide smooth surfaces with T-junctions where T-splines cannot have a smooth parameterization. GT-constructions display a uniform highlight linedistribution on input meshes where alternatives, such as Catmull-Clark subdivision, exhibit oscillations. [ABSTRACT FROM AUTHOR]

Motorcyclists too often collide with other road users who pull out of side roads in front of them. These other road users typically report making all the necessary visual checks, despite failing to see the approaching motorcycle. These Look But Fail To See errors appear to be attenuated in road users who themselves have motorcycling experience, suggesting that motorcycle exposure may lower thresholds for spotting these vulnerable road users through natural perceptual learning. This raises the possibility that perceptual training could improve car drivers’ abilities to spot motorcycles. Two experiments are reported. The first experiment demonstrated that a T-junction task, requiring participants to detect an approaching vehicle in briefly displayed images, was sensitive to participants’ motorcycle experience, with dual drivers (who both ride motorcycles and drive cars) performing better than average car drivers. Following this, a second experiment split the car drivers into 2 groups. One group undertook a Pelmanism task requiring participants to match pairs of motorcycles, while the control group had to match pairs of fruit. When the two groups were re-tested on the T-junction task, the group who had undergone perceptual training for motorcycles via the Pelmanism task, were better able to identify approaching motorcycles, but not approaching cars. The results suggest that gamification of perceptual training for motorcycle detection provides a novel opportunity to improve driver safety. [ABSTRACT FROM AUTHOR]

We employ numerical simulations to investigate the breakup of droplets in micro- and nanoscale T junctions, which are used to produce small droplets from a large droplet. For this purpose a Volume f Fluid (VOF) based method is used and for verifying the reliability of the numerical outcomes, the results are compared with the available experimental and analytical results. Our results reveal that breakup time and breakup length of the droplets play important roles in handling these systems optimally. Our results also indicate that for nanoscale Tjunctions by increasing the capillary number the performance increases while for the micro-scale systems there is a specific capillary number for which the system is in its optimum condition.

In this paper, an experimental investigation on the influence of glue on the low frequency vibroacoustic performance (up to 200 Hz) of wooden T-junctions is presented along with a discussion of modelling issues related to the junctions. The mock-ups studied represent cut-outs of full size timber floor assemblies typically used in Sweden. Their dynamic performance was first studied experimentally by means of modal analysis. Moreover, finite element (FE) simulations of the T-junctions were carried out to establish reliable prediction tools, using the measurement data as calibration input. Modelling issues were addressed to investigate the influence of different features that must be taken into account when simulating the connections as part of larger structures. Guidelines for modelling these type of connections, when developing low frequency FE predictive tools, are presented here. [ABSTRACT FROM AUTHOR]

Asymmetric T-junctions have recently emerged as a promising tool in microfluidics. However, previous studies of the droplet formation mechanism are largely limited to symmetric T-junctions. In this work, the droplet formation in universal T-junctions, including both symmetric and asymmetric T-junctions, is investigated by a three-dimensional color-gradient lattice Boltzmann model. A three-dimensional color-conserving boundary condition is developed to model fluid–surface interactions, which suppresses the spurious velocities near the contact lines and improves numerical accuracy. Model verification is conducted by the partial wetting test and the droplet formation in a symmetric T-junction. Then, an in-depth study is performed for universal T-junctions. In both symmetric and asymmetric T-junctions, the droplet length is linearly dependent on flow rate ratio at low capillary number, and the droplet formation successively undergoes squeezing, dripping and jetting regimes as the capillary number increases. By investigating the local pressure and velocity field, we find that the upstream pressure and viscous force respectively dominates the droplet formation in squeezing and dripping regimes. In squeezing regime, the pressure fluctuates significantly, and the fluctuation amplitude and frequency decrease with the channel width ratio; while in dripping regime, the pressure fluctuation is negligibly small, and the viscous force is found to decrease with the channel width ratio. Consequently, the droplet size increases with the channel width ratio in both regimes. In addition, the viscosity ratio and surface wettability are found to be influential to the formation regime, droplet shape and size for various channel width ratios and capillary numbers, and play important roles in droplet formation. [ABSTRACT FROM AUTHOR]

An alternative device to the well-known septum polarizer is proposed, which also provides the double function of an orthomode and a polarizer. It is based on a waveguide T-junction between a common dual-polarization waveguide and a tilted rectangular single-mode waveguide, and offers an intrinsically shorter geometry in the axial dimension, an advisable property when searching for compact antena assemblies. The analysis of this new device is presented, along with the derivation and introduction of the S-parameters referred to the circularly polarized modes in the common waveguide. The working principle of the proposed T-junction is also explained in detail. A breadboard is designed, and its simulation and measurement results are presented. As a conclusion, the proposed device seems worthy of comparison in its electrical performances to the septum polarizer, showing some advantages in terms of geometrical dimensions and manufacturability. [ABSTRACT FROM PUBLISHER]

In three experiments, two independent samples of 12 observers each visually inspected modified versions of Titchener's ⊥ from which the T-junctions had been deleted. For Experiment 1, the ⊥'s two lines had been replaced by dashed lines not meeting in a common point; for Experiment 2, the ⊥ had been reduced to five dots, representing the original lines' end- and midpoints; and for Experiment 3 (in which the second sample of observers served), the ⊥ had been dissected into two separate lines, differently spaced from each other. Observers haptically indicated the lengths of the two orthogonal lines of the modified ⊥s and verbally judged their relative lengths or the distances between the corresponding dots. The common perceptual illusions persisted in Experiments 1 and 2, but were markedly weakened in Experiment 3. Implications for a neurophysiological account of the illusions in terms of bottom-up, long-range interactions between orientation-sensitive mechanisms versus top-down activation of a figural schema are spelled out. [ABSTRACT FROM AUTHOR]

Both perceptual errors (failing to perceive) and appraisal errors (failing to make a correct judgment about safety) could explain the relatively high number of pulling out at the junctions involving approaching motorcycles in relation to cars. Two experiments were conducted to investigate the effect of exposure to motorcycles on these types of errors by comparing drivers from Malaysia where motorcycles are very common with drivers from the UK where motorcycles are rare. Experiment 1 investigated drivers’ ability to perceive approaching vehicles (car or motorcycle) located at different distances (near, intermediate and far) on UK and Malaysian roads. There was no difference between Malaysian and UK drivers in overall ability to perceive the approaching vehicles but Malaysian drivers were relatively good at perceiving motorcycles at further distances. Experiment 2 investigated drivers’ judgments about whether or not it was safe to pull out on the same roads and found that Malaysian drivers were more likely to judge it was safe to pull out as compared to UK drivers. Findings suggest that high exposure to motorcycles may reduce vehicle effects on perception for Malaysian drivers. However they may make more risky appraisals about safety of pulling out, which might contribute to the high accident and fatality rates in Malaysia. [ABSTRACT FROM AUTHOR]

This article proposes a theoretical overview of the distribution of fluid flow through manifolds composed of parallel channels connected through T-junctions to a distributor and to a collector channel, thus composing a ladder-like network. Such networks are used in solar heaters, fuel cells, heat exchanger plates, and other engineering devices, one issue being to achieve a nearly uniform distribution. This first part focuses on the discrete mesoscopic momentum and energy balances governing the T-junctions, with particular attention to the empirical, flow-rate and geometry dependent, pressure change coefficients. By 'mesoscopic', it is meant that the control volume for the balance equations includes the junction zone and that the local flow-field in that zone is not described. The existing results and correlations for these coefficients are reviewed, compared, and synthesized. In keeping with the discrete character of the channel network, the overall network relations are compacted as a single non-linear finite-difference equation relating the flow-rates in the different segments of the distributor. This formulation is suitable for convenient numerical resolution even when all the coefficients are allowed to vary with local conditions. The conditions for simplifications, such as assuming constancy of certain coefficients, are carefully investigated. A number of approximate analytical, semi-explicit or explicit solutions are constructed. In particular, an original view of the structure of these solutions is proposed, relying on an invariance property which is demonstrated, and on the analogy with the classical McCabe-Thiele construction in chemical engineering. These approximations are compared to exact numerical solutions. [ABSTRACT FROM AUTHOR]

We employ numerical simulations to investigate the breakup of droplets in micro- and nanoscale T junctions, which are used to produce small droplets from a large droplet. For this purpose a Volume f Fluid (VOF) based method is used and for verifying the reliability of the numerical outcomes, the results are compared with the available experimental and analytical results. Our results reveal that breakup time and breakup length of the droplets play important roles in handling these systems optimally. Our results also indicate that for nanoscale Tjunctions by increasing the capillary number the performance increases while for the micro-scale systems there is a specific capillary number for which the system is in its optimum condition [ABSTRACT FROM AUTHOR]

Abstract: A new coefficient to characterize the global behaviour of adiabatic compressible flow at T-junctions is proposed. The new coefficient is defined according to the conclusions derived from the uncertainty propagation analysis of the total pressure loss coefficient defined by Miller for compressible flow. The numerical results obtained using the new linking between branches coefficient definition, , show a logarithmic relationship with mass flow rate ratio between branches, q, and the extrapolated Mach number in the common branch, , for all flow types studied in a 90° T-junction. Reliable and practical two parameters or global correlations, , have been obtained. These correlations can be easily implemented as boundary conditions into 1D global simulation codes. [Copyright &y& Elsevier]

A well-known reading pitfall in computed tomography (CT) colonography is posed by artifacts at T-junctions, i.e., locations where air-fluid levels interface with the colon wall. This paper presents a scale-invariant method to determine material fractions in voxels near such T-junctions. The proposed electronic cleansing method particularly improves the segmentation at those locations. The algorithm takes a vector of Gaussian derivatives as input features. The measured features are made invariant to the orientation-dependent apparent scale of the data and normalized in a way to obtain equal noise variance. A so-called parachute model is introduced that maps Gaussian derivatives onto material fractions near T-junctions. Projection of the noisy derivatives onto themodel yields improved estimates of the true, underlying feature values. The method is shown to render an accurate representation of the object boundary without artifacts near junctions. Therefore, it enhances the reading of CT colonography in a 3-D display mode. [ABSTRACT FROM AUTHOR]

Abstract: This work is focussed on the development of a numerical simulation model that predicts the thermal and fluid-dynamic behaviour of the two-phase flow distribution in systems with multiple branching tubes like manifolds. The geometry of a simulated branching system is represented as a set of tubes connected together by means of junctions. On one side, the in-tube evaporation/condensation phenomena are simulated by means of a one-dimensional two-phase flow model, and on the other side, the splitting/converging flow phenomena occurring at junctions are predicted with appropriate junction models obtained from the technical literature. The global flow distribution is calculated using a semi-implicit pressure based method (SIMPLE-like algorithm) where the continuity and momentum equations of the whole domain are solved and linked with both the in-tube two-phase flow model and the junction models. In the present paper, the flow distribution model is described and its most significant aspects are detailed. Furthermore, the model is validated against experimental and numerical data found in the open literature. The numerical predictions are compared against an adiabatic single-phase flow manifold system working with water and also against a two-phase flow upwardly oriented manifold system working with carbon dioxide. In addition to this, a numerical comparison of a manifold system with two different orientations is carried out. Concluding remarks about the possibilities that this kind of model offers are presented in the last section. [Copyright &y& Elsevier]

Abstract: Inhomogeneous surrounds can produce either asymmetrical or symmetrical increment/decrement induction by orienting T-junctions to selectively group a test patch with surrounding regions [Melfi, T., & Schirillo, J. (2000). T-junctions in inhomogeneous surrounds. Vision Research, 40, 3735–3741]. The current experiments aimed to determine where T-junctions are processed by presenting each eye with a different image so that T-junctions exist only in the fused percept. Only minor differences were found between retinal and cortical versus cortical-only conditions, indicating that T-junctions are processed cortically. [Copyright &y& Elsevier]

Abstract: New experimental correlations to characterize energy losses in adiabatic compressible flow at 90-degree T-junctions and their expanded uncertainties are presented. These new correlations are based on a new linking between branches coefficient definition, , and show a logarithmic relationship with mass flow rate ratio between branches, q, and the extrapolated Mach number in the common branch, , for all the different flow types studied. The extrapolated properties up to the junction are calculated, from measurement sections, subtracting the frictional losses using the Fanno fluid flow model. These two parameters or global correlations, , can be easily implemented as boundary conditions into 1-D global simulation codes. [Copyright &y& Elsevier]

The human urge to represent the three-dimensional world using two-dimensional pictorial representations dates back at least to Paleolithic times. Artists from ancient to modern times have struggled to understand how a few contours or color patches on a flat surface can induce mental representations of a three-dimensional scene. This article summarizes some of the recent breakthroughs in scientifically understanding how the brain sees that shed light on these struggles. These breakthroughs illustrate how various artists have intuitively understood paradoxical properties about how the brain sees, and have used that understanding to create great art. These paradoxical properties arise from how the brain forms the units of conscious visual perception; namely, representations of three-dimensional boundaries and surfaces. Boundaries and surfaces are computed in parallel cortical processing streams that obey computationally complementary properties. These streams interact at multiple levels to overcome their complementary weaknesses and to transform their complementary properties into consistent percepts. The article describes how properties of complementary consistency have guided the creation of many great works of art. [ABSTRACT FROM AUTHOR]

Abstract: Within industrial applications it is rare to operate wholly under steady-state conditions and there will always be at least one time-dependent parameter. Such transients, in flowrate or pressure, can occur over a short time period, in the order of seconds or minutes, or evolve over a more substantial time period of hours, or even days. The longer this time frame, the less severe impact the transient will have on the operation of equipment. If the flowrate is subjected to a sudden change, any equipment must be either capable of responding quickly to adapt to the variation or be able to absorb the change without adversely affecting the overall system performance. Examples of general transient situations, involve plant shutdown and start-up, changes in flowrates in response to planned operating conditions, like bringing another oil well on line, and emergency situations. Baker et al. [2007. Controlling the phase separation of gas–liquid flows at horizontal T-junctions. American Institute of Chemical Engineers Journal 53, 1908–1915] suggested a novel development of T-junctions for compact phase separation applications based correctly on steady-state observations. However, since it must be expected that transients are an unavoidable problem within industry, this shortfall in knowledge has to be a concern and a probable reason why T-junctions are not used in situations where they could be advantageous. A survey of available literature shows that very little work has been conducted under transient flow conditions. As such, this initial study provides insight into the complex mechanisms and dynamics that occur when transient two-phase flows enter a specific T-junction separator. [Copyright &y& Elsevier]

Abstract: Corners and junctions are landmarks characterized by the lack of differentiability in the unit tangent to the image level curve. Detectors based on differential operators are not, by their own definition, the best posed as they require a higher degree of differentiability to yield a reliable response. We argue that a corner detector should be based on the degree of continuity of the tangent vector to the image level sets, work on the image domain and need no assumptions on neither the image local structure nor the particular geometry of the corner/junction. An operator measuring the degree of differentiability of the projection matrix on the image gradient fulfills the above requirements. Because using smoothing kernels leads to corner misplacement, we suggest an alternative fake response remover based on the receptive field inhibition of spurious details. The combination of both orientation discontinuity detection and noise inhibition produce our inhibition orientation energy (IOE) landmark locator. [Copyright &y& Elsevier]

This paper presents a novel wet etching method for LiNbO3 using electric-field-assisted proton exchange. By applying voltage with appropriate polarity on designed electrodes placed on both sides of substrate, the induced electric-field distribution can effectively suppress or enhance proton diffusion in the lateral and depth directions. Thus, the proton-exchanged range in LiNbO3 can be expertly manipulated. Because the proton-exchanged region can be removed by using a mixture of HF/HNO3 acids, the proposed wet-etching method can effectively control the shape of the etched region in the LiNbO3 substrate. Under appropriate electrode and proton-exchange parameters, a vertical sidewall with smooth surface is successfully produced, which makes fabricating reflection mirrors and T-junctions in LiNbO3 possible. By utilizing the proposed wet-etching method, optical integrated circuits with higher integration density can be fabricated in LiNbO3. [ABSTRACT FROM PUBLISHER]

We investigate the formation of single wall carbon nanotube T-junctions via the fusing of two nanotubes. We propose energetically efficient pathways for formation (9, 0)–(10, 0)–(9, 0) and (5, 5)–(10, 0)–(5, 5) T-junctions. In the proposed scheme all carbon atoms maintain their sp2 arrangements throughout and transformation is achieved through creation/annihilation of topological defects. We use tight-binding molecular dynamics simulation to investigate energetic of proposed mechanism. [ABSTRACT FROM AUTHOR]

The division of gas/liquid flow at a large diameter T-junction has been studied experimentally. The misdistribution of the phases has been quantified for horizontal semi-annular flow. Film thickness variations about the circumference of the inlet and outlet pipes have been obtained using conductivity techniques. In addition, liquid depth profiles within the junction have been measured. The data have been compared with available theoretical models. [Copyright &y& Elsevier]

The experiments reported herein probe the visual cortical mechanisms that control near-far percepts in response to two-dimensional stimuli. Figural contrast is found to be a principal factor for the emergence of percepts of near versus far in pictorial stimuli, especially when stimulus duration is brief. Pictorial factors such as interposition (Experiment 1) and partial occlusion (Experiments 2 and 3) may cooperate, as generally predicted by cue combination models, or compete with contrast factors in the manner predicted by the FACADE model. In particular, if the geometrical configuration of an image favors activation of cortical bipole grouping cells, as at the top of a T-junction, then this advantage can cooperate with the contrast of the configuration to facilitate a near-far percept at a lower contrast than at an X-junction. Varying the exposure duration of the stimuli shows that the more balanced bipole competition in the X-junction case takes longer exposures to resolve than the bipole competition in the T-junction case (Experiment 3). [ABSTRACT FROM AUTHOR]

This paper presents two dimensional (2-D) finite difference time domain (FDTD) simulations of low-loss right-angle waveguide bends, T-junctions and crossings, based on high index-contrast waveguides. Such structures are essential for the dense integration of optical components. Excellent performance characteristics are obtained by designing the waveguide intersection regions as low-Q resonant cavities with certain symmetries and small radiation loss. A simple analysis, based on coupled mode theory in time, is used to explain the operation principles and agrees qualitatively with the numerical results [ABSTRACT FROM PUBLISHER]

Microwave devices comprising magnetized ferrite in contact with superconductor circuits designed to eliminate magnetic field penetration of the superconductor have demonstrated phase shift without significant conduction losses. The device structures are adaptable to low- or high-T/sub c/ superconductors. A nonoptimized design of a ferrite phase shifter that employs niobium or YBCO meanderlines has produced over 1000 degrees of differential phase shift with a figure of merit exceeding 1000 degrees/dB at X band. By combining superconductor meanderline sections with alternating T junctions on a ferrite substrate in a configuration with three-fold symmetry, a low-loss three-port switching circulator has been demonstrated. [ABSTRACT FROM AUTHOR]

• Successful numerical prediction of two-phase flow separation in mini-manifold. • Interface split at a series of millimeter size T-junctions. • The separation is studied as a function of flow pattern rather than a single bubble. • Results are validated against experimental data. • Results offer a good platform for studying underlying phenomena. This work assesses the possibility/feasibility of utilizing the CFD to predict water-air separation in a mini-manifold at ambient conditions. The manifold consists of a header with three reduced T-junctions. A combination of the manifold size and the operating parameters yields a computationally demanding surface tension dominant flow. A computational model of separation is based on the interface tracking technique and the FVM framework. The results are validated against the experiment. Findings show that the separation can be successfully predicted, even under such conditions. Analysis of computational cost revealed that the long computational time is the only limiting factor for regular CFD use in such applications. The paper's novelty is in the successful prediction of phase separation. Such an approach requires flow pattern prediction capabilities in the straight parts of the manifold and physically sound interface split prediction at the T-junctions that have not been explored previously in such a way. [ABSTRACT FROM AUTHOR]

The actual behavior of welded T-junctions in tubular structures depends strongly on the topology of the junction at the joint level. In finite element analysis, beam-type elements are usually employed due to their simplicity and low computational cost, even though they cannot reproduce the joints topologies and characteristics. To adjust their behavior to a more realistic situation, elastic elements can be introduced at the joint level, whose characteristics must be determined through costly validations. This paper studies the optimization and implementation of the validation data, through the creation of an optimal surrogate model based on neural networks, leading to a model that predicts the stiffness of elastic elements, introduced at the joint level based on available data. The paper focuses on how the neural network should be chosen, when training data is very limited and, more importantly, which of the available data should be used for training and which for verification. The methodology used is based on a Monte Carlo analysis that allows an exhaustive study of both the network parameters and the distribution and choice of the limited data in the training set to optimize its performance. The results obtained indicate that the use of neural networks without a careful methodology in this type of problems could lead to inaccurate results. It is also shown that a conscientious choice of training data, among the data available in the problem of choice of elastic parameters for T-junctions in finite elements, is fundamental to achieve functional surrogate models. [ABSTRACT FROM AUTHOR]

Analysis-suitable T-splines (ASTS) including both extraordinary points and T-junctions are used to solve Kirchhoff–Love shell problems. Extraordinary points are required to represent surfaces with arbitrary topological genus. T-junctions enable local refinement of regions where increased resolution is needed. The benefits of using ASTS to define shell geometries are at least two-fold: (1) The manual and time-consuming task of building a new mesh from scratch using the CAD geometry as an input is avoided and (2) C 1 or higher inter-element continuity enables the discretization of shell formulations in primal form defined by fourth-order partial differential equations. A complete and state-of-the-art description of the development of ASTS, including extraordinary points and T-junctions, is presented. In particular, we improve the construction of C 1 -continuous non-negative spline basis functions near extraordinary points to obtain optimal convergence rates with respect to the square root of the number of degrees of freedom when solving linear elliptic problems. The applicability of the proposed technology to shell analysis is exemplified by performing geometrically nonlinear Kirchhoff–Love shell simulations of a pinched hemisphere, an oil sump of a car, a pipe junction, and a B-pillar of a car with 15 holes. Building ASTS for these examples involves using T-junctions and extraordinary points with valences 3, 5, and 6, which often suffice for the design of free-form surfaces. Our analysis results are compared with data from the literature using either a seven-parameter shell formulation or Kirchhoff–Love shells. We have also imported both finite element meshes and ASTS meshes into the commercial software LS-DYNA, used Reissner–Mindlin shells, and compared the result with our Kirchhoff–Love shell results. Excellent agreement is found in all cases. The complexity of the shell geometries considered in this paper shows that ASTS are applicable to real-world industrial problems. • Detailed description of bi-cubic non-negative smooth analysis-suitable T-splines. • Improved treatment of C 1 -continuous extraordinary points. • Optimal convergence rates with respect to n d o f . • Geometries of increasing complexity, including an automotive B-pillar. • Comparisons with the literature and the commercial software LS-DYNA. [ABSTRACT FROM AUTHOR]