scholarly journals A Comparative Study on Evaluation Methods of Fluid Forces on Cartesian Grids

2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
Taku Nonomura ◽  
Junya Onishi
Keyword(s):  
Reliable Method ◽  
Cartesian Grid ◽  
Object Motion ◽  
Shear Stresses ◽  
Ghost Cell ◽  
Object Surface ◽  
Ghost Fluid Method ◽  
Grid Systems ◽  
Fluid Forces ◽  
Different Types

We investigate the accuracy and the computational efficiency of the numerical schemes for evaluating fluid forces in Cartesian grid systems. A comparison is made between two different types of schemes, namely, polygon-based methods and mesh-based methods, which differ in the discretization of the surface of the object. The present assessment is intended to investigate the effects of the Reynolds number, the object motion, and the complexity of the object surface. The results show that the mesh-based methods work as well as the polygon-based methods, even if the object surface is discretized in a staircase manner. In addition, the results also show that the accuracy of the mesh-based methods is strongly dependent on the evaluation of shear stresses, and thus they must be evaluated by using a reliable method, such as the ghost-cell or ghost-fluid method.

scholarly journals Determination of Cohesion values of Rock Materials using Double Shear Jaws

2018 ◽  
Author(s):  
Eren Komurlu ◽  
Aysegul Durmus Demir
Keyword(s):  
Failure Mechanisms ◽  
Shear Stresses ◽  
Compressive Test ◽  
Contact Conditions ◽  
Testing Conditions ◽  
Rock Materials ◽  
Double Shear ◽  
Different Types ◽  
Shear Planes

In this study, experimental and numerical analyses were carried out for determination of cohesion values of different types of rock materials using double shear jaws (DSJ) which can be practically used with the conventional compressive test equipment, to make shear planes in the rock core specimens. Effects of various parameters like jaw dimensions, gaps between triple blocks of the DSJ and contact conditions of the jaw on the results and validity of the cohesion test were investigated considering failure mechanisms of rock core specimens. Instead of a failure induced due to the shear stresses, tensile failures are mostly seen from conventional shear testing conditions. For a valid failure under the control of shear stresses, a DSJ design was suggested to be used in cohesion determination tests according to the results obtained from this study.

scholarly journals Estimation Method of Fluorescent Donaldson Matrices Based on Multispectral Imaging Data

2020 ◽  
Vol 2020 (28) ◽  
pp. 227-231
Author(s):  
Shoji Tominaga
Keyword(s):  
Reliable Method ◽  
Multispectral Imaging ◽  
Estimation Method ◽  
Visible Range ◽  
Multiple Response ◽  
Imaging Data ◽  
Object Surface ◽  
Spectral Functions ◽  
Simulation Experiments ◽  
Image Acquisition System

This paper proposes a compact and reliable method to estimate the bispectral Donaldson matrices of fluorescent objects by using multispectral imaging data. We suppose that an image acquisition system allows multiple illuminant projections to the object surface and multiple response channels in the visible range. The Donaldson matrix is modeled as a twodimensional array with the excitation range (350, 700 nm) and the reflection and emission ranges (400, 700 nm). The observation model is described using the spectral sensitivities of a camera and the spectral functions of reflectance, emission, and excitation. The problem of estimating the spectral functions is formulated as a least squares problem to minimize the residual error of the observations and the roughness of the spectral functions. An iterative algorithm is developed to obtain the optimal estimates of the whole spectral functions. The performance of the proposed method is examined in simulation experiments using multispectral imaging data in detail.

A Detailed Procedure for Reliable Preparation of Tem Samples Using Fib Milling

1997 ◽  
Vol 480 ◽  
Author(s):  
D. H.-I Su ◽  
H. T. Shishido ◽  
F. Tsai ◽  
L. Liang ◽  
F. C. Mercado
Keyword(s):  
Integrated Circuit ◽  
Reliable Method ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Beam Spreading ◽  
The Past ◽  
Detailed Procedure ◽  
Defect Sites ◽  
Different Types

AbstractAlthough many publications have discussed focused ion beam (FIB) preparation of TEM samples, few have presented a detailed, step-by-step milling procedure. This is a summary of techniques that evolved over the past 3 years in our laboratory. In addition to describing more traditional mechanical pre-thinning techniques, we introduce a method to pre-thin samples down to thicknesses of the order of 20 μm within 1 hour using a wafer dicing saw. We then discuss different ways to handle mechanically difficult samples such as those prone to delaminate. Our approach to FIB milling is designed to minimize the effects of ion-beam spreading which is responsible for most of the failures to prepare good FIBTEM samples. The technique is presented in a step-by-step fashion including a simple yet reliable method to terminate FIB milling. Examples are shown to illustrate applications to different types of problems including - precision cross-sectioning of integrated circuit (IC) devices, cross-sectioning of samples prone to delamination, and cross-sectioning of specific defect sites. Finally, we discuss the effect of artifacts in the quality of TEM samples.

scholarly journals Comparative analysis on heat transfer of various fin profile using solid works: A systematic review

2021 ◽  
Vol 850 (1) ◽  
pp. 012029
Author(s):  
Vaishnav Madhavadas ◽  
Dibyarup Das ◽  
Kaustubh Anand Mohta ◽  
S. Senthur Prabu
Keyword(s):  
Heat Transfer ◽  
Systematic Review ◽  
Convection Heat Transfer ◽  
Object Surface ◽  
Pin Fin ◽  
Number Of Factors ◽  
Different Types ◽  
Extended Surfaces ◽  
Solid Works ◽  
Shape And Size

Abstract Fins are widely used to enhance the amount of heat transfer by improving the rate of convection heat transfer. Fins are also known as extended surfaces, i.e., extrusions from the object surface. There are numerous kinds of fins, and based on the shape and size, the amount of heat transfer through the fins will differ. Heat transfer depends upon the geometry of the fin and depends upon a number of factors such as the nature of the fin surface, the ambient temperature; the velocity of the air, etc. In this present study, the systematic review is carried out by critically analyzing the different types of fin profile such as plain rectangular fin, wavy fin, circular pin fin, and rectangular pin fin to increase the fins efficiency. The outcome from this study reveals that the heat transferred by the fins is mainly dependent on the fins profile (type and shape), length, angle, and surface area. Alongside the orientation of the fins, porosity, thermo-geometry also affects the fins’ efficiency.

Algorithmic Fingertip Repositioning for Enhanced In-Hand Manipulation of the Objects

2021 ◽  
pp. 1-17
Author(s):  
Rajesh Kumar ◽  
Sudipto Mukherjee
Keyword(s):  
Contact Point ◽  
Object Motion ◽  
The Other ◽  
Object Surface ◽  
Force Closure ◽  
Finger Gaiting

Abstract This paper focuses on a method to relocate the robotic fingertips on the surface of the object when the fingertips instantaneously hold the object under precision grasp. Precision grasp involves holding the object using fingertips. Finger gaiting involves repositioning the fingertips on the surface of the object and then manipulation of the object. During repositioning, one contact point leaves the object surface and recontacts at the other point. A metric is defined on the set of feasible grasp configurations to limit deviation from force closure during repositioning of the fingertips. Then, a manipulability based metric is described to search for the optimal goal grasp states on the object's surface. The manipulability based metric is used to search the grasp state to relocate the contacts, such that the range of object motion is increased.

scholarly journals Theoretical Analysis of Fractional Viscoelastic Flow in Circular Pipes: General Solutions

2020 ◽  
Vol 10 (24) ◽  
pp. 9093
Author(s):  
Dmitry Gritsenko ◽  
Roberto Paoli
Keyword(s):  
Fractional Calculus ◽  
Biomedical Applications ◽  
Viscoelastic Flow ◽  
Shear Stresses ◽  
Viscoelastic Flows ◽  
Extensive Literature ◽  
Circular Pipes ◽  
Different Types ◽  
Pipe Radius ◽  
Fractional Orders

Fractional calculus is a relatively old yet emerging field of mathematics with the widest range of engineering and biomedical applications. Despite being an incredibly powerful tool, it, however, requires promotion in the engineering community. Rheology is undoubtedly one of the fields where fractional calculus has become an integral part of cutting-edge research. There exists extensive literature on the theoretical, experimental, and numerical treatment of various fractional viscoelastic flows in constraint geometries. However, the general theoretical approach that unites several most commonly used models is missing. Here we present exact analytical solutions for fractional viscoelastic flow in a circular pipe. We find velocity profiles and shear stresses for fractional Maxwell, Kelvin–Voigt, Zener, Poynting–Thomson, and Burgers models. The dynamics of these quantities are studied with respect to normalized pipe radius, fractional orders, and elastic moduli ratio. Three different types of behavior are identified: monotonic increase, resonant, and aperiodic oscillations. The models developed are applicable in the widest material range and allow for the alteration of the balance between viscous and elastic properties of the materials.

scholarly journals Microstructural Changes during Degradation of Biobased Poly(4-hydroxybutyrate) Sutures

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2024
Author(s):  
Ina Keridou ◽  
Lourdes Franco ◽  
Luis J. del Valle ◽  
Juan C. Martínez ◽  
Lutz Funk ◽  
...  
Keyword(s):  
Enzymatic Degradation ◽  
Fiber Axis ◽  
Surface Erosion ◽  
Shear Stresses ◽  
Thermal Treatments ◽  
Gradual Change ◽  
X Ray Diffraction ◽  
Microstructural Changes ◽  
X Ray ◽  
Different Types

Fibers of poly(4-hydroxybutyrate) (P4HB) have been submitted to both hydrolytic and enzymatic degradation media in order to generate samples with different types and degrees of chain breakage. Random chain hydrolysis is clearly enhanced by varying temperatures from 37 to 55 °C and is slightly dependent on the pH of the medium. Enzymatic attack is a surface erosion process with significant solubilization as a consequence of a preferent stepwise degradation. Small angle X-ray diffraction studies revealed a peculiar supramolecular structure with two different types of lamellar stacks. These were caused by the distinct shear stresses that the core and the shell of the fiber suffered during the severe annealing process. External lamellae were characterized by surfaces tilted 45° with respect to the stretching direction and a higher thickness, while the inner lamellae were more imperfect and had their surfaces perpendicularly oriented to the fiber axis. In all cases, WAXD data indicated that the chain molecular axis was aligned with the fiber axis and molecules were arranged according to a single orthorhombic structure. A gradual change of the microstructure was observed as a function of the progress of hydrolysis while changes were not evident under an enzymatic attack. Hydrolysis mainly affected the inner lamellar stacks as revealed by the direct SAXS patterns and the analysis of correlation functions. Both lamellar crystalline and amorphous thicknesses slightly increased as well as the electronic contrast between amorphous and crystalline regions. Thermal treatments of samples exposed to the hydrolytic media revealed microstructural changes caused by degradation, with the inner lamellae being those that melted faster.

scholarly journals THE ROLE OF FOX-H FUNCTION IN ANALYTIC AND FRACTIONAL MODELING OF HELICITY OF CYLINDER: FRACTIONAL GENERALIZED BURGER FLUID

Fractals ◽  
2020 ◽  
Vol 28 (08) ◽  
pp. 2040050
Author(s):  
KASHIF ALI ABRO ◽  
ILYAS KHAN ◽  
KOTTAKKARAN SOOPPY NISAR
Keyword(s):  
Helical Flow ◽  
Velocity Fields ◽  
Rheological Parameters ◽  
Series Expansions ◽  
Shear Stresses ◽  
Gamma Functions ◽  
Fractional Modeling ◽  
Different Types ◽  
Fractional Models

In this paper, the analytic and fractional solutions of governing differential equations for helical flow of cylindrical nature have been presented. The series expansions and Laplace and Hankel transforms are applied to the governing equation of generalized Burger fluid flow for generating gamma functions. The analytical solutions of velocity fields and shear stresses are obtained through Caputo fractional approach. In order to justify the initial and boundary conditions, infinite series are invoked for expressing the analytical results of velocity fields and shear stresses in terms of [Formula: see text] Fox-H function. At the end, few rheological parameters have been analyzed on four different types of models as shown in graphs. Finally, a comparative analysis of ordinary and fractional models has been focussed for angular and oscillating velocities of helical flow generated by circular cylinder.

Mirroring in Group Counseling: Analyzing Narrative Innovations

2017 ◽  
Vol 48 (4) ◽  
pp. 391-419 ◽  
Author(s):  
Giovanna Esposito ◽  
António P. Ribeiro ◽  
Miguel M. Gonçalves ◽  
Maria Francesca Freda
Keyword(s):  
University Students ◽  
Group Counseling ◽  
Reliable Method ◽  
Coding System ◽  
System A ◽  
Counseling Group ◽  
Different Types ◽  
Group Member ◽  
Innovative Moments

The aim of this case study is to demonstrate how an innovative group counseling method, the narrative mediation path, promotes reflective mirroring in a group of underachieving university students. We used an adaptation of the innovative moments coding system, a reliable method for studying change by tracking narrative innovations throughout the intervention. The transcripts of the seven sessions of a single narrative mediation path counseling group were analyzed, and three types of innovative moments were identified: self-directed innovative moments (those directed at the participants themselves), other-directed innovative moments (those directed at another group member), and group-directed innovative moments (those directed at the group as a whole). To study the narrative sequences containing both other-directed or group-directed innovative moments and self-directed innovative moments, a microgenetic approach was adopted. Results suggested that across the narrative mediation path counseling sessions, different types of reflecting mirroring emerged, based on supporting, interpreting, and connecting members’ experiences.

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