Extensive Theory of Force-Approach Relations of Elastic Spheres in Compression and in Impact

1989 ◽  
Vol 111 (2) ◽  
pp. 163-168 ◽  
Author(s):  
Yoichi Tatara
Keyword(s):  
Elastic Medium ◽  
Relative Position ◽  
Large Deformations ◽  
Hard Spheres ◽  
Center Of Mass ◽  
Initial Position ◽  
Experimental Result ◽  
Hertz Theory ◽  
Wide Range ◽  
Small Deformations

The prevailing Hertz theory in contact and in impact is based on the total compressive displacement of a semi-infinite elastic body. This paper considers displacements of finite elastic medium in each of elastic spheres and presents analytically extensive force-approach relations of the Hertz theory for two elastic spheres in statical compression and in impact. In the statical conditions, expansive displacements of the mutual surf ace of contact due to compressive displacements by the reactions, which act on the opposite surfaces in a distance equal to each diameter, are considered analytically in two approximate cases. The force-approach relations obtained here are much closer than the Hertz’s one in a wide range of deformations to one experimental result carried out for one rubber sphere. In impact, it is considered that relative position of each center of mass of the impacting spheres accompanying asymmetrical deformations is shifted from the initial position. The force-approach relation has another extensive term different from the Hertz’s relation and from the above relations in the statical conditions. In the case of very small deformations for hard spheres, the extensive terms can be neglected and the Hertz theory is valid in compression and in impact. The present force-approach relations can be applicable to the cases of large deformations in compression and in impact.

scholarly journals A broadbanded pressure differential wave energy converter based on dielectric elastomer generators

2021 ◽  
Author(s):  
Michele Righi ◽  
Giacomo Moretti ◽  
David Forehand ◽  
Lorenzo Agostini ◽  
Rocco Vertechy ◽  
...  
Keyword(s):  
Wave Energy ◽  
Large Deformations ◽  
Dielectric Elastomer ◽  
Wave Energy Converter ◽  
Pressure Differential ◽  
Design Stage ◽  
Small Scale ◽  
Energy Converter ◽  
Wide Range ◽  
The Waves

AbstractDielectric elastomer generators (DEGs) are a promising option for the implementation of affordable and reliable sea wave energy converters (WECs), as they show considerable promise in replacing expensive and inefficient power take-off systems with cheap direct-drive generators. This paper introduces a concept of a pressure differential wave energy converter, equipped with a DEG power take-off operating in direct contact with sea water. The device consists of a closed submerged air chamber, with a fluid-directing duct and a deformable DEG power take-off mounted on its top surface. The DEG is cyclically deformed by wave-induced pressure, thus acting both as the power take-off and as a deformable interface with the waves. This layout allows the partial balancing of the stiffness due to the DEG’s elasticity with the negative hydrostatic stiffness contribution associated with the displacement of the water column on top of the DEG. This feature makes it possible to design devices in which the DEG exhibits large deformations over a wide range of excitation frequencies, potentially achieving large power capture in a wide range of sea states. We propose a modelling approach for the system that relies on potential-flow theory and electroelasticity theory. This model makes it possible to predict the system dynamic response in different operational conditions and it is computationally efficient to perform iterative and repeated simulations, which are required at the design stage of a new WEC. We performed tests on a small-scale prototype in a wave tank with the aim of investigating the fluid–structure interaction between the DEG membrane and the waves in dynamical conditions and validating the numerical model. The experimental results proved that the device exhibits large deformations of the DEG power take-off over a broad range of monochromatic and panchromatic sea states. The proposed model demonstrates good agreement with the experimental data, hence proving its suitability and effectiveness as a design and prediction tool.

Simplified coupling power model for fibers fusion

2009 ◽  
Vol 17 (3) ◽  
Author(s):  
J. Saktioto ◽  
J. Ali ◽  
M. Fadhali
Keyword(s):  
Refractive Index ◽  
Propagation Constant ◽  
Tunable Filter ◽  
Experimental Result ◽  
Total Power ◽  
Optical Parameters ◽  
Coupling Region ◽  
Ratio Distribution ◽  
Hydrogen Flow ◽  
Wide Range

AbstractFiber coupler fabrication used for an optical waveguide requires lossless power for an optimal application. The previous research coupled fibers were successfully fabricated by injecting hydrogen flow at 1 bar and fused slightly by unstable torch flame in the range of 800–1350°C. Optical parameters may vary significantly over wide range physical properties. Coupling coefficient and refractive index are estimated from the experimental result of the coupling ratio distribution from 1% to 75%. The change of geometrical fiber affects the normalized frequency V even for single mode fibers. V is derived and some parametric variations are performed on the left and right hand side of the coupling region. A partial power is modelled and derived using V, normalized lateral phase constant u, and normalized lateral attenuation constant, w through the second kind of modified Bessel function of the l order, which obeys the normal mode and normalized propagation constant b. Total power is maintained constant in order to comply with the energy conservation law. The power is integrated through V, u, and w over the pulling length of 7500 µm for 1-D. The core radius of a fiber significantly affects V and power partially at coupling region rather than wavelength and refractive index of core and cladding. This model has power phenomena in transmission and reflection for an optical switch and tunable filter.

An Efficient Smartphone Assisted Indoor Localization with Tracking Approach using Glowworm Swarm Optimization Algorithm

2021 ◽  
pp. 101-107
Author(s):  
Mohammad Alshehri ◽  
Keyword(s):  
Real Time ◽  
Indoor Localization ◽  
Initial Position ◽  
Swarm Optimization ◽  
The Real ◽  
Assisted Navigation ◽  
Glowworm Swarm Optimization ◽  
Tracking Process ◽  
Wide Range ◽  
Localization And Tracking

Presently, a precise localization and tracking process becomes significant to enable smartphone-assisted navigation to maximize accuracy in the real-time environment. Fingerprint-based localization is the commonly available model for accomplishing effective outcomes. With this motivation, this study focuses on designing efficient smartphone-assisted indoor localization and tracking models using the glowworm swarm optimization (ILT-GSO) algorithm. The ILT-GSO algorithm involves creating a GSO algorithm based on the light-emissive characteristics of glowworms to determine the location. In addition, the Kalman filter is applied to mitigate the estimation process and update the initial position of the glowworms. A wide range of experiments was carried out, and the results are investigated in terms of distinct evaluation metrics. The simulation outcome demonstrated considerable enhancement in the real-time environment and reduced the computational complexity. The ILT-GSO algorithm has resulted in an increased localization performance with minimal error over the recent techniques.

scholarly journals Finite Element Software for Rubber Products Design

2018 ◽  
Vol 3 (1) ◽  
pp. 13-20
Author(s):  
Dávid Huri
Keyword(s):  
Finite Element ◽  
Complex Analysis ◽  
Large Deformations ◽  
Material Behavior ◽  
Nonlinear Material ◽  
Material Models ◽  
Finite Element Software ◽  
Highly Nonlinear ◽  
Wide Range ◽  
Different Types

Automotive rubber products are subjected to large deformations during working conditions, they often contact with other parts and they show highly nonlinear material behavior. Using finite element software for complex analysis of rubber parts can be a good way, although it has to contain special modules. Different types of rubber materials require the curve fitting possibility and the wide range choice of the material models. It is also important to be able to describe the viscoelastic property and the hysteresis. The remeshing possibility can be a useful tool for large deformation and the working circumstances require the contact and self contact ability as well. This article compares some types of the finite element software available on the market based on the above mentioned features.

Improved Algorithm on Wide Range Positioning for Partial Discharge in Substation

2013 ◽  
Vol 860-863 ◽  
pp. 2177-2181
Author(s):  
Xi Ran Wang ◽  
Huai Dong Liu ◽  
Yi Fan He ◽  
Qi Ming Zhao ◽  
He Wu
Keyword(s):  
Electrical Discharge ◽  
Partial Discharge ◽  
Signal Strength ◽  
Received Signal Strength ◽  
Experimental Result ◽  
Wide Range ◽  
Positioning Algorithm ◽  
Received Signal Strength Indication ◽  
Improved Algorithm

This paper proposes a Improved positioning algorithm of electrical partial discharge applied for substations. This algorithm is based on received signal strength indication, and taken practical condition of sensors into consideration by replenishing beacon nodes. Compared with traditional trilateral weighting positioning algorithm, this paper introduces indefinite amount of localization perpendicular lines and combined them with trilateral districts to calculate the weighting result, which can reduce error. This model meets the requirement of reality that the height of electrical discharge spots differentiate from the height of the plane formed by beacon nodes (signal sensors). The experimental result indicates that the revised position model proposed by this paper can effectively fit the condition of monitoring hardware. Error of this algorithm is less than that of traditional trilateral localization.

Monte Carlo and Perturbation Calculations for a Triangular Well Fluid

1974 ◽  
Vol 52 (1) ◽  
pp. 80-88 ◽  
Author(s):  
Damon N. Card ◽  
John Walkley
Keyword(s):  
Monte Carlo ◽  
Hard Spheres ◽  
Low Density ◽  
Monte Carlo Data ◽  
Density Region ◽  
Wide Range ◽  
Model Fluid ◽  
High Density Region ◽  
Superposition Approximation ◽  
Triangular Well Potential

Monte Carlo data have been generated for a simple model fluid consisting of hard spheres with an attractive triangular well potential. The ranges spanned by the temperature and density are as follows. [Formula: see text] and [Formula: see text]. The machine data have been compared to the modern perturbation theories of (i) Barker, Henderson, and Smith and (ii) Weeks, Chandler, and Andersen. Comparison with the machine data shows that the latter theory is successful in the high density region only, but over a wide range of temperature. The Barker–Henderson approach is best in the low density region but the use of the superposition approximation limits the utility of this theory at high densities.

On the Inflow Phenomenon in Near Field of Buoyant Jet at Low Froude Number

2012 ◽  
Author(s):  
Atsushi Maeda ◽  
Takayuki Yamagata ◽  
Nobuyuki Fujisawa
Keyword(s):  
Reynolds Number ◽  
Froude Number ◽  
Near Field ◽  
Quantitative Information ◽  
Experimental Result ◽  
Inflow Rate ◽  
Buoyant Jet ◽  
Square Duct ◽  
Wide Range ◽  
Low Froude Number

In the present paper, the inflow phenomenon in the near-field of a buoyant jet issuing from a square duct is studied by using scanning LIF and scanning PIV measurements. The scanning LIF visualization allows an insight into the critical condition of the inflow phenomenon in a wide range of Froude number and Reynolds number. While, the scanning PIV allows the quantitative information on the inflow rate through the duct exit. The experimental result shows that the critical Froude number increases with an increase in Reynolds number in the duct exit up to Reynolds number 2,000, though it is weakened at higher Reynolds number. The examination of the inflow rate indicates that the large magnitude of the inflow rate occurs in the lower Froude number and Reynolds number.

Analysis of Triangular Microchannel Under Forced Convection Heat Transfer Condition for Laminar Flow Condition

2013 ◽  
Author(s):  
D. A. Kamble ◽  
B. S. Gawali
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Water Flow ◽  
Flow Rate ◽  
Heat Input ◽  
Water Flow Rate ◽  
Temperature Drop ◽  
Experimental Result ◽  
Rate Condition ◽  
Wide Range

Micro-convection is a strategic area in transport phenomena, since it is the basis for a wide range of miniaturized high-performance heat transfer applications. Surface area is one of the important parameter for high flux heat transfer in microchannel performance. This experimental study deals with heat transfer using triangular microchannel having hydraulic diameters of 321μm and 289μm. Experimentation is carried out for triangular microchannel set for different heat input and flow rate condition. Triangular microchannel are manufactured with EDM technology. Testing of microchannel under laminar flow is considered with different tip angle, spacing, and length of microchannels. The different microchannels made up of copper material with 29 microchannel each having three different sets of length of 50 mm, 70 mm and 90 mm respectively. Tip angles for triangular microchannel is varied 50 ° and 60 ° with width of 30 mm each respectively are analyzed numerically. Spacing between triangular microchannels is also varied and 300μm and 400μm are considered for the analysis. Water flow rate is considered laminar flow. The flow rate of water is varied from 0.0167 kg/sec to 0.167 kg/sce to carry away heat. It is observed that as hydraulic diameters increase the heat transfer coefficient decreases. As the heat input to microchannel increases from 10 Watt to 100 Watt the temperature drop across varies from 2° C to 22°C as water flow rate increases. The numerical analysis is done using computer C programming. Experimental result differ from theoretical for temperature drop with variation of 2°C to 5°C. It is also observed that in all triangular microchannels its geometry i.e. tip angle and hydraulic diameter are dominant parameters which influences on rate of heat transfer. With increasing channel depth, increases flow passage area therefore enhances heat transfer sufficiently. From experimentation a Nu number correlation is proposed with considering tip angle, length, spacing of microchannel and other related parameters.

scholarly journals Non-Abelian Bloch oscillations in higher-order topological insulators

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
M. Di Liberto ◽  
N. Goldman ◽  
G. Palumbo
Keyword(s):  
Quantum Dynamics ◽  
Topological Insulators ◽  
Berry Phase ◽  
Center Of Mass ◽  
Higher Order ◽  
Topological Properties ◽  
Bloch Oscillations ◽  
Abelian Gauge ◽  
Synchronization Mechanism ◽  
Wide Range

AbstractBloch oscillations (BOs) are a fundamental phenomenon by which a wave packet undergoes a periodic motion in a lattice when subjected to a force. Observed in a wide range of synthetic systems, BOs are intrinsically related to geometric and topological properties of the underlying band structure. This has established BOs as a prominent tool for the detection of Berry-phase effects, including those described by non-Abelian gauge fields. In this work, we unveil a unique topological effect that manifests in the BOs of higher-order topological insulators through the interplay of non-Abelian Berry curvature and quantized Wilson loops. It is characterized by an oscillating Hall drift synchronized with a topologically-protected inter-band beating and a multiplied Bloch period. We elucidate that the origin of this synchronization mechanism relies on the periodic quantum dynamics of Wannier centers. Our work paves the way to the experimental detection of non-Abelian topological properties through the measurement of Berry phases and center-of-mass displacements.

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