Conical Model Research Articles

An Analytical Modeling of Conical Gate-All-Around Tunnel Field Effect Transistor

In this paper a new analytical modeling of Conical Gate-All-Around Tunnel Field Effect Transistor has been proposed and verified by TCAD Simulation. The Electrostatic parameters of the conical structure are modeled from two dimensional Poisson’s Equation using Parabolic Approximation Method. The electrostatic performance of surface potential and drain current of conical structure is compared with the cylindrical structure. The present model with optimized tapering ratio of 0.9 parades enhanced electrostatic behavior compared to cylindrical structure. The results divulge the conical device model provides better ON drain current, high transconductance and reduced threshold voltage at drain side. Thus, the conical structure can be a possible replacement of cylindrical structure with optimized tapering ratio for low-power applications.

An analytical model for the transversely forced flame transfer functions of conical and V-flame dynamics

Heat release rate perturbations of two-dimensional asymmetric premixed slot flames subjected to transverse perturbations, so called flame transfer functions (FTFs), are theoretically studied in this paper. The proposed models of both the two-dimensional conical flame and V-flame are studied based upon the linear analysis. The flame front dynamic response under the transverse disturbance is captured and solved using the G-equation model. The analytical solution of the FTF is derived using different oncoming velocity perturbation models, in order to reveal the flame heat release rate response mechanism to the transverse disturbances. In the two-dimensional conical flame model, the flame front tip moves with the transverse perturbations, which in turn also affects the FTF. In the two-dimensional V-flame model, the flame front tips are intersected by the flame branches and the unburned gas boundaries; this also contributes to the different behaviours of the FTF. The linear flame tip dynamics and the explicit analytical models of the FTFs of both the conical flame model and the V-flame model are proposed and validated. Results show that the transverse disturbance propagation velocity model has a significant effect on the FTF. The movement of the flame tip is also affected by the transverse convection models.

Examining the validity of the two-dimensional conical model to describe the three-dimensional ZrTe5

Understanding the low-energy excitation state in three-dimensional layered compound ZrTe5 remains a challenging problem in the study of novel topological materials. Recently, a two-dimensional conical model was proposed to explain the experimental optical spectroscopy in the 3D ZrTe5, Martino et al. [Phys. Rev. Lett. 122, 217402 (2019)]. Motivated by this work, in this paper, we perform a systematic theoretical study on the optical conductivity of this model in both cases without and with an external magnetic field to further demonstrate the validity of this model and to recover new physics.We find that there exist completely different characteristics for optical conductivity along different directions, due to anisotropic low-energy excitations in this two-dimensional conical model. Specifically, for the interband optical conductivity, we find asymptotic dependence on the optical frequency as Re(\sigma_x)\sim\omega^{1/2} and Re(\sigma_z)\sim{\omega}^{3/2}, which are universal both in the gapped insulator phase and Weyl semimetal phase. For the magneto-optical conductivity, on the contrary, Re(\sigma^B_{x/z}) shows distinct signatures in the gapped insulator phase and Weyl semimetal phase, which can help distinguish the two phases. Our results, to be verified in future experiments, could provide more insights into the understanding of the topological nature of ZrTe5.

Root canal conicity estimation of primary maxillary central and lateral incisors-A study by Nano-CT.

The objective of the study was to estimate the conicity of the root canals of maxillary central and lateral incisors by computed nanotomography (Nano-CT). This in vitro study included nine extracted primary maxillary central incisors and 12 maxillary lateral incisors, which were subjected to Nano-CT analysis. The resulting images of each tooth were reconstructed using the OnDemand3D software, and root canal area, volume, and taper analysis were performed using the free FreeCAD 0.18 software for the 3D computer-aided design (CAD) model. Data were statistically analysed using the Stata v14.0 software, adopting a significance level of 5%. The results presented the mean value of the diameter and area of theroot canal of primary central and lateral incisors. In addition, the taper values for both dental groups between points D0-D5, D5-D7, and D7-D10 were determined. Considering the diameters obtained over the entire length of the root, with a length of 12mm, a conical model was constructed. Detailed knowledge of root morphology of maxillary central and lateral incisors of primary dentition by means of Nano-CT is important to achieve faster, more accurate, and efficient endodontic treatments.

Finite-element inverse analysis of residual stress for laser welding based on a contour method

The thermal effect of laser welding degrades the local material properties, and this inevitably leads to thermal deformation and thermal residual stress in welded joints. In this study, the residual stress distribution of laser-welded Al–Li alloy parts was measured by a combination of the contour method and finite-element simulation. First, the contour deformation of the cutting surfaces of welded parts resulting from the release of residual stress was measured by a coordinator. Then, the reverse contour deformation was applied to the finite-element model as the displacement boundary condition to invert the full-field residual stress of the cutting surface. Furthermore, a thermal/structural sequential coupling analysis method was used to establish a complete three-dimensional finite-element model of a laser-welded plate and calculate the residual stress field, taking the actual weld morphology as the characteristic parameter of the heat source, using the improved conical heat source model of laser welding. The result is consistent with the results of the contour method.

Buckling stability performance assessment of CFRP-strengthened conical shells under uniform external pressure

Abstract Thin-walled conical shells are extensively used in a variety of engineering applications. The major concern in the design of these thin-walled structures is the buckling failure. One potential strategy for improving the buckling stability performance of conical shells may be the employment of carbon fiber reinforced polymer (CFRP) composite materials for reinforcement purposes. On this basis, a detailed numerical study is conducted on the buckling performance of CFRP-strengthened conical shells under uniform external pressure and reported in this paper. To this end, numerous conical shell models with different slenderness ratios, strengthened circumferentially and meridionally at different locations and directions using CFRP stripes with 0 ° , 45 ° , and 90 ° fiber orientations are investigated through linear and nonlinear buckling analyses using ABAQUS finite element software. The results and findings of this research are indicative of effectiveness of the reinforcing CFRP laminates in increasing the stiffness and buckling strength of such structures. Specifically, the circumferential reinforcement of the bottom third region using [45 ° /90 ° ] reinforcing CFRP stripes is found to be the superior approach for improving the buckling stability performance of conical shells.

Instability of Conical Shells with Multiple Dimples under Axial Compression

Thin-walled conical shells are primary structures in offshore application. Presence of imperfection can considerably reduce the load carrying capacity of such structures when in use. This study examines the buckling behavior of axially compressed imperfect steel cones using the multiple perturbation load analysis (MPLA). This is both a numerical and experimental study. Eight conical shell test models were manufactured in pairs and collapsed under axial compression: two perfect, and the remaining six with MPLA imperfection amplitude, A, of 0.56, 1.12 and 1.68 having two equally-spaced dimples on each cones. Experimental test results for all the conical shell models and the accompanying numerical predictions are given in this paper. Repeatability of experimental data was good. The errors within each pair were 3%, 13%, 1% and 0%. In addition, there was a good comparison between experimental and numerical data. The ratio of experimental to numerical buckling loads varies from 0.91 to 1.13.

A Multi-Component Conical Spring Model of Soft Tissue in Virtual Surgery

With the rapid development of optical system and medical robotic technology, the virtual surgery approach has achieved good progress but also faces many challenges. Physical and mechanical models of soft tissue characteristics have been a hot research topic in this field. In the present investigation, a physical model with a new multi-component conical spring is proposed, which replaces the cylindrical spring of the traditional mass-spring model. In the new model, a multi-component spring structure has been incorporated that consists of a conical spring and a linear spring in series. Based on the analysis of the nonlinear characteristics of soft tissue, the mechanical model was established to correspond better with the physical behavior. To determine the parameters for the mechanical model, the Euler method was deployed. The determination of the model parameters was achieved using physical tests. Result simulation experiments confirmed that the behavior of the new multi-component conical spring model proposed in the present paper gives results that are closer to those obtained from real-world physical tests than were data given by either the mass-conical-spring model or the mass-spring-model. Average difference, maximum difference and mean square error values were used for the evaluation. The accuracy of simulations for soft tissue virtual surgery can be improved by application of the new model developed in the present study.

Statistical distributions of the tuning and coupling collective modes at a conical intersection using the hierarchical equations of motion.

We investigate the possibility of extracting the probability distribution of the effective environmental tuning and coupling modes during the nonadiabatic relaxation through a conical intersection. Dynamics are dealt with an open quantum system master equation by partitioning a multistate electronic subsystem out of all the nuclear vibrators. This is an alternative to the more usual partition retaining the tuning and coupling modes of a conical intersection in the active subsystem coupled to a residual bath. The minimal partition of the electronic system generally leads to highly structured spectral densities for both vibrational baths and requires a strongly nonperturbative non-Markovian master equation, treated here by the hierarchical equations of motion (HEOMs). We extend-for a two-bath situation-the procedure proposed by Shi et al. [J. Chem. Phys. 140, 134106 (2014)], whereby the information contained in the auxiliary HEOM matrices is exploited in order to derive the nuclear dissipative wave packet, i.e., the statistical distribution of the displacement of the two tuning and coupling collective coordinates in each electronic state and the coherence. This allows us to visualize the distribution, all along the nonadiabatic decay. We explore a large parameter space for a symmetrical conical intersection model and a symmetrical initial Franck-Condon preparation. Some parameters could be controlled by external fields, while others are molecule dependent and could be designed by molecular engineering. We illustrate the relation between the strongly coupled electronic and bath dynamics together with a geometric measure of non-Markovianity.

A study of the vibration and lay-up optimization of rotating cross-ply laminated nanocomposite blades

A comprehensive understanding of the vibration characteristics of rotating blades is critical to avoid resonance fracture. This paper presents the vibration analysis and lay-up optimization of rotating pre-twisted laminated functionally graded CNTs reinforced composite (FG-CNTRC) shallow conical shells. A numerical shallow conical shell model is proposed, and the displacement fields of the shell model are described via the first-order shear deformation theory. Considering the rotating speed, the governing equation of the rotating pre-twisted laminated conical shell is derived, and then solved using the meshless kp-Ritz method. We carry out the comparison studies to demonstrate the accuracy and efficiency of the present model in dealing with the vibrations of this kind of structures. Detailed parametric studies are then performed and demonstrate that the CNT configuration, pre-twisted angle, and stacking sequence play essential roles in vibration behaviors of rotating FG-CNTRC blade. With the nondimensional frequency parameter being the optimization objective function, a genetic algorithm is employed to search for the optimal layering sequence of the rotating shallow conical shells. The optimized results demonstrate that the GA serves as a useful tool for sequence optimization of rotating blade in terms of improving the vibration characteristics.

Numerical prediction of temperature distribution and residual stresses on plasma arc welded thin titanium sheets

ABSTRACT The residual stresses are responsible for most of the failure of weldments in nuclear industry and the temperature distribution is the key measure to predict these residual stresses. The residual stresses are produced due to the non-uniform heating and cooling of the material and thus generating inhomogeneous plastic deformation in the components during the welding process. The Plasma arc welded 2 mm thick Ti-6Al-4V plate is taken for the study to predict the weld bead geometry, temperature distribution and residual stresses. The temperature distribution is predicted through the transient thermal analysis in ANSYS Parametric Design Language (APDL) using Three-Dimensional Conical Heat Source Model & Dhinakaran’s model and the simulated results are validated against the experimental outcomes. The temperature-dependent material properties with the temperature range varying from the room temperature to the melt pool temperature are considered for transient thermal analysis. The radiation heat transfer becomes predominant at high-temperature regimes; hence the radiation effects are imposed into the convective heat transfer coefficient. The weld bead geometry, temperature distribution and the residual stresses are predicted at various regimes of the plate. It is observed that the theoretical values obtained from the FEM Simulation are good in agreement with the experimental values.

Turbulization of a wake behind the double roughness elements in a hypersonic boundary layer

The study of the effect of close placing of two individual elements of roughness with the cylindrical shape on the nature of laminar-turbulent transition were performed. Experiments were performed for a blunt conical model with the radius 9 mm at Mach number M = 5. These double elements of roughness with different heights and divergence angles between elements were allocated at the blunted nose of the tested model. Measurements with a hot-wire anemometer provided information about the averaged and unsteady parameters of the boundary layer in the wake behind the roughness elements. For all types of roughness, we confirmed existence of an effective height of roughness; for the heights above the effective one, we observe deformation of the boundary layer margin and the growth of non-equilibrium in the wake. Process of turbulization behind a double roughness element (similar to the case of single roughness) is accompanied by the generation of longitudinal vortices and by the deformation of the velocity profile. Depending on this deformation, pulsations in the wake either enhance or decline. In contrast to the single roughness configuration, the double element roughness decreases the mass flowrate for a narrow range of angles (and fullness of the boundary layer profile is more significant). Meanwhile, flow turbulization occurs right behind the single element of turbulization, for the case of double element turbulization, the main gain in the mass flowrate occurs with the wake (developing from the boundary between twin elements). Roughness has significant influence on unsteady characteristics of the boundary layer (when the height of roughness element is lower than the effective height). The wake downstream the double elements roughness exhibits the interaction between vortices, and this reduces the effective Reynolds number (compared to the case of single roughness).

Micro-mechanical investigation of railway ballast behavior under cyclic loading in a box test using DEM: effects of elastic layers and ballast types

Ballasted tracks are the commonly used railway track systems with constant demands for reducing maintenance cost and improved performance.Elastic layers are increasingly used for improving ballasted tracks. In order to better understand the effects of elastic layers, physical understanding at the ballast particle level is crucial. Here, discrete element method (DEM) is used to investigate the effects of elastic layers – under sleeper pad (text {USP}) at the sleeper/ballast interface and under ballast mat (text {UBM}) at the ballast/bottom interface – on micro-mechanical behavior of railway ballast. In the DEM model, the Conical Damage Model (CDM) is used for contact modelling. This model was calibrated in Suhr et al. (Granul Matter 20(4):70, 2018) for the simulation of two different types of ballast. The CDM model accounts for particle edge breakage, which is an important phenomenon especially at the early stage of a tamping cycle, and thus essential, when investigating the impact of elastic layers in the ballast bed. DEM results confirm that during cyclic loading, text {USP} reduces the edge breakage at the sleeper/ballast interface. On the other hand, text {UBM} shows higher particle movement throughout the ballast bed. Both the edge breakage and particle movement in the ballast bed are found to influence the sleeper settlement. Micro-mechanical investigations show that the force chain in deeper regions of the ballast bed is less affected by text {USP} for the two types of ballast. Conversely, dense lateral forces near to the box bottom were seen with text {UBM}. The findings are in good (qualitative) agreement with the experimental observations. Thus, DEM simulations can aid to better understand the micro-macro phenomena for railway ballast. This can help to improve the track components and track design based on simulation models taking into account the physical behavior of ballast.Graphical

Magnetoelectric domains and their switching mechanism in a Y -type hexaferrite

By employing resonant X-ray microdiffraction, we image the magnetisation and magnetic polarity domains of the Y-type hexaferrite Ba$_{0.5}$Sr$_{1.5}$Mg$_2$Fe$_{12}$O$_{22}$. We show that the magnetic polarity domain structure can be controlled by both magnetic and electric fields, and that full inversion of these domains can be achieved simply by reversal of an applied magnetic field in the absence of an electric field bias. Furthermore, we demonstrate that the diffraction intensity measured in different X-ray polarisation channels cannot be reproduced by the accepted model for the polar magnetic structure, known as the 2-fan transverse conical (TC) model. We propose a modification to this model, which achieves good quantitative agreement with all of our data. We show that the deviations from the TC model are large, and may be the result of an internal magnetic chirality, most likely inherited from the parent helical (non-polar) phase.

Inferring the jet parameters of active galactic nuclei using Bayesian analysis of VLBI data with a non-uniform jet model

ABSTRACTThe physical parameters of the jets of active galactic nuclei observed with Very Long Baseline Interferometry (VLBI) are usually inferred from core-shift measurements or from the flux and size measured at the peak frequency of the synchrotron spectrum. Both methods are preceded by modelling the observed VLBI jet structure with simple Gaussian templates. Here we infer the jet parameters using an inhomogeneous jet model directly, bypassing the modelling of the source structure with a Gaussian template or image deconvolution. We apply Bayesian analysis to multifrequency VLBA observations of radio galaxy NGC 315 and find that its parsec-scale jet is well described by an inhomogeneous conical model. Our results favour an electron–positron jet. We also detect a component as a part of a counter jet. Its position implies the presence of an external absorber with a steep density gradient close (r = 0.1 pc) to the central engine.

Elastoplastic and nonlinear analysis of functionally graded axisymmetric shell structures under thermal environment, using a conical frustum finite element model

This work presents the formulation for static bending analysis of functionally graded axisymmetric plate/shell type structures under mechanical loading, and considering different structural behaviours: linear, geometric nonlinear and material nonlinear. The implemented model is based on a simple conical frustum finite element with 2 nodes, and 3 degrees of freedom per node, which includes shear deformation effects, and it shows to be extremely efficient in the analysis of axisymmetric shells subjected to axisymmetric loading. The used of reduced numerical integration procedure is essential for its success when applied to thin shells. The formulation accounts for the calculation of displacements and through-thickness stress distribution. The solutions for some illustrative examples involving variation of volume fractions are obtained, and the results are presented and compared with numerical alternative models when available, and discussed.

Optimal tuning of FOPID controller based on PSO algorithm with reference model for a single conical tank system

The fractional order proportional integral derivative controller (FOPID) replaces the conventional PID controller for its immense merits such as its simple structure, better set point tracking, high disturbance rejection, higher capability of handling model uncertainties in nonlinear and real time applications. This paper addresses the effectiveness of the FOPID controller on a level control of single conical system in real time. It is one of the classical nonlinear control problem and its shape not only contributes the proper mixing of liquids and also guarantee to drainage of solid wastes. This study, a dual loop controller is proposed and constructed with a master process and slave process for a level control of a single conical tank system. In the slave process, the output response obtained by the traditional PID controller combined with the conical tank reference model and compared with the output response of the master process. The obtained error signal is used to dynamically correct the parameters of the FOPID controller in the master process. The tuning of FOPID controller is a challenging task due to its presence of extra parameters and it efficiently carried out by particle swarm optimization (PSO) algorithm. The obtained result reveals that the Proposed PSO optimized FOPID controller with reference model demonstrated the better set point tracking, smooth controller response than other conventional integer order controllers.

The structure and pressure characteristics of graduated compression stockings: experimental and numerical study

The incorporation of pressure levels and pressure gradients in the design of compression stockings offers excellent potential to enhance function in the sport science, clinical research and rehabilitation fields. Yet, the connection of processing parameters and structure accompanying the pressure characteristic of current graduated compression stockings (GCS) is not well quantitatively studied. To bridge this knowledge gap, this study aims to analyze the effects of processing parameters, such as elastane yarn count, loop length and elastane feeding tension, on the structure and pressure behavior of GCS in our work. In addition, to investigate the mechanism of the pressure characteristic, two numerical models, the cylinder model and the conical model, are employed to predict the pressure value and the pressure gradient of stockings. The experimental results of the statistical analysis indicate that the loop length is a key factor to control the wale density, length of stockings and final pressure values. Moreover, the elastane feeding tension could affect the course density, girth of stockings and pressure gradient. On the other hand, the numerical results reveal that the conical model is suited for predicting the pressure values because of the change in radius of the limb in the model. The entire experimental and numerical work provide the mechanism for the study basis of processing, structure and pressure characteristics of GCS.

Investigation of charging and discharging characteristics of a horizontal conical shell and tube latent thermal energy storage device

In this study, a numerical model to analyse the charging and discharging characteristics of a horizontal shell and tube type Latent Heat Storage (LHS) prototype is presented. The system comprises of Sodium Nitrate as phase change material (PCM) in the shell side and flow of air as heat transfer fluid (HTF) in the tube side. The effective heat capacity approach is followed while solving the fluid flow and energy interactions in the PCM. The design is optimized by modifying a cylindrical shell into a conical shell heat exchanger system. The optimized values of diameters at inlet and outlet of the conical shell are found to be 98.6 mm and 54 mm, respectively having a cone angle of 3.4°. A performance comparison is made with a cylindrical shell system of equivalent storage capacity. 3-D numerical simulations performed on the proposed system revealed that an innovation in the design leads to enhanced heat transfer rate caused by uniform melting throughout the system. Further, the conical shell model is numerically simulated for various operating parameters such as inlet HTF velocity and temperature. Also, the effect of fins attached on the HTF tube on the performance of the system is analysed. With the advent of advanced heat exchanger design, there is a greater scope of obtaining higher heat transfer rates employing the proposed conical shell and tube LHS system.

Topological Map Construction Based on Region Dynamic Growing and Map Representation Method

In the human–machine interactive scene of the service robot, obstacle information and destination information are both required, and both kinds of information need to be saved and used at the same time. In order to solve this problem, this paper proposes a topological map construction pipeline based on regional dynamic growth and a map representation method based on the conical space model. Based on the metric map, the construction pipeline can initialize the region growth point on the trajectory of the mobile robot. Next, the topological region is divided by the region dynamic growth algorithm, the map structure is simplified by the minimum spanning tree, and the similar region is merged by the region merging algorithm. After that, the parameter TM (topological information in the map) and the parameter OM (occupied information in the map) are used to represent the topological information and the occupied information. Finally, a topological map represented by the colored picture is saved by converting to color information. It is highlighted that the topological map construction pipeline is not limited by the structure of the environment, and can be automatically adjusted according to the actual environment structure. What’s more, the topological map representation method can save two kinds of map information at the same time, which simplifies the map representation structure. The experimental results show that the map construction method is flexible, and that resources such as calculation and storage are less consumed. The map representation method is convenient to use and improves the efficiency of the map in preservation.