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) C1 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 C1-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 C1-continuous extraordinary points.•Optimal convergence rates with respect to ndof.•Geometries of increasing complexity, including an automotive B-pillar.•Comparisons with the literature and the commercial software LS-DYNA.
•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.
Reconfigurable T‐junction DNA Origami Young, Katherine G.; Najafi, Behnam; Sant, William M. ...
Angewandte Chemie,
September 7, 2020, Volume:
132, Issue:
37
Journal Article
Peer reviewed
Open access
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.
Bringing DNA into the fold: A foldable polymer DNA origami assembled using T‐junction motifs is presented. It is shown 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.
A novel methodology to perform mode conversion from rectangular fundamental TE 10 mode to circular TE<inline-formula> <tex-math notation="LaTeX">_{n1} </tex-math></inline-formula> (<inline-formula> ...<tex-math notation="LaTeX">n </tex-math></inline-formula> = 2, 3, <inline-formula> <tex-math notation="LaTeX">4, \ldots </tex-math></inline-formula>)/TE<inline-formula> <tex-math notation="LaTeX">_{0p} </tex-math></inline-formula> (<inline-formula> <tex-math notation="LaTeX">p </tex-math></inline-formula> = 1, 2, <inline-formula> <tex-math notation="LaTeX">3, \ldots </tex-math></inline-formula>)/TE<inline-formula> <tex-math notation="LaTeX">_{1q} (q </tex-math></inline-formula> = 2, 3, <inline-formula> <tex-math notation="LaTeX">4, \ldots </tex-math></inline-formula>) modes with similar topologies is presented in this article. The mode converter consists of two sections: a novel H-plane T-junction-based rectangular TE<inline-formula> <tex-math notation="LaTeX">_{m0} </tex-math></inline-formula> (<inline-formula> <tex-math notation="LaTeX">m </tex-math></inline-formula> = 2, 3, <inline-formula> <tex-math notation="LaTeX">4, \ldots </tex-math></inline-formula>) mode launcher and a rectangular TE<inline-formula> <tex-math notation="LaTeX">_{m0} </tex-math></inline-formula>-circular TE<inline-formula> <tex-math notation="LaTeX">_{n1} </tex-math></inline-formula>/TE<inline-formula> <tex-math notation="LaTeX">_{0p} </tex-math></inline-formula>/TE<inline-formula> <tex-math notation="LaTeX">_{1q} </tex-math></inline-formula> mode converter. This kind of mode converter possesses good comprehensive performance and is highlighted by three primary advantages: 1) it is flexible to produce various circular TE modes and rectangular TE<inline-formula> <tex-math notation="LaTeX">_{m\mathrm {0}} </tex-math></inline-formula> modes; 2) the mode converter has a relatively simple and easy-to-fabricate geometry, making it especially suitable for the terahertz-band operation; and 3) it possesses a high mode conversion efficiency over a wide bandwidth, which is adequate to satisfy most of the application requirements. The analysis of mode conversion principle, numerical simulations, microfabrication, and experimental measurement of two H-band (220-325 GHz) prototypes are described. Back-to-back measurement results exhibited good agreement with simulation predictions having considered the conductor loss. A 3-dB transmission bandwidth of 56.7 GHz (231.4-288.1 GHz)/42.1 GHz (244.0-286.1 GHz) was experimentally obtained for the <inline-formula> <tex-math notation="LaTeX">{\mathrm {TE}}^{\square}_{10}-{\mathrm {TE}}_{01}^{\circ}/{\mathrm {TE}}_{31}^{\circ} </tex-math></inline-formula> mode converter.
Amodal Completion of Color Todorović Dejan
Gestalt Theory,
08/2022, Volume:
44, Issue:
1-2
Journal Article
Peer reviewed
Open access
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%).
•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.
Vehicles wishing to pass on the toll road must diverge from the traffic flow on public roads. The toll road movement consists of low vehicles (LV) and heavy vehicles (HV). The public road movement is ...a mixed traffic flow consisting of LV, HV, motorcycles, and unmotorized vehicles. Traffic lights are used at the T-junction of the toll road gate for travel safety management. The traffic lights that implement a fixed-time strategy should be optimized for efficiency. This study aims to review the safety of travel management at T-junctions for the toll road gate when adaptive traffic lights are used. The structural complexity of mathematical modeling with Petri net is used to analyze and measure the feasibility study. Results illustrate that the structural complexity of the traffic lights that implement a fixed time strategy equals 0.387. It is equal to 0.489 for the adaptive traffic lights. The structural complexity of adaptive traffic lights is 25% higher than conventional systems that implement a fixed-time strategy. The adaptive traffic lights time strategy is feasible for travel safety for road users. The travel time is efficient and comfortable because the delay is low. Furthermore, traffic lights can adjust to the demand of vehicles queuing.
•The pressure distribution and phase separation parameters of branches are analyzed.•The phase split performance between two branches is compared.•An optimal value of branches’ distance is found.•The ...phase separation of branches reaches best when the distance is 2.0 m.•An empirical correlation is proposed to predict the split efficiency of branch.
T-junction is widely used as a phase separation component to separate two-phase flow because of its simple structure and low cost. Previous studies suggest that an increase in the number of T-junction branches is conducive to raise phase separation efficiency. In this paper, the pressure distribution and phase separation performance of two-phase flow of R134a in horizontal double T-junctions are studied. The phase separation performance between two branches is compared. The parameters including inlet quality (0.3-0.6), inlet mass flow rate (10.0 g s−1-25.0 g s−1), diameter ratio (1, 0.75) and the distance between two branches (0.3 m-2.6 m) are studied. The inlet mass flow rate has significant influence on the phase separation, and the separation performance reaches best when it is 10.0 g s−1. Results show that the change of parameters has greater influence on the phase separation performance of the second branch compared with the first branch. When the distance between branches is 2.0 m, the total phase separation capacity of the branches reaches the best. By comparing the phase separation of branches, it can be found that when the distance increases gradually, the phase separation performance of the second branch first increases and then decreases, indicating that there is a specific distance that maximizes the gas phase separation efficiency of branches. The optimal distance is also related to the mass flow ratio of the second branch. Therefore, an empirical correlation equation which can accurately predict the gas phase separation efficiency of the second branch is proposed.
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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.
•3D color-gradient LBM with color-conserving boundary condition is developed.•Droplet formation in universal T-junctions are extensively studied.•Local pressure is monitored and analyzed to ...understand the formation mechanism.•Channel width ratio, viscosity ratio and surface wettability significantly affect the droplet formation.
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.
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