scholarly journals Experimental Investigations and development of mathematical model to estimate drop diameter and jet length

2021 ◽  
Author(s):  
Amitava Roy ◽  
G. Suneel ◽  
J.K. Gayen ◽  
K.V. Ravi ◽  
R.B. Grover
Keyword(s):  
Mathematical Model ◽  
Experimental Investigations ◽  
Drop Diameter ◽  
Jet Length

scholarly journals The Role of Cell Motility in Metastatic Cell Dominance Phenomenon: Analysis by a Mathematical Model

2000 ◽  
Vol 3 (1) ◽  
pp. 63-77 ◽  
Author(s):  
A. V. Kolobov ◽  
A. A. Polezhaev ◽  
G. I. Solyanik
Keyword(s):  
Mathematical Model ◽  
Cell Motility ◽  
Threshold Value ◽  
Experimental Investigations ◽  
Metastatic Cell ◽  
Metastatic Cells ◽  
Motile Cells ◽  
Cell Subpopulations ◽  
Cell Motion ◽  
Slow Growing

Metastasis is the outcome of several selective sequential steps where one of the first and necessary steps is the progressive overgrowth or dominance of a small number of metastatic cells in a tumour. In spite of numerous experimental investigations concerning the growth advantage of metastatic cells, the mechanisms resulting in their dominance are still unknown. Metastatic cell overgrowth occurs even if doubling time of the metastatic subpopulation is shorter than that of all others subpopulations in a heterogeneous tumour. In order to examine the hypothesis that under conditions of competition of cell subpopulations for common substrata cell motility of the slow-growing subpopulation can result in its dominance in a heterogeneous tumour, a mathematical model of heterogeneous tumour growth is suggested. The model describes two cell subpopulations which can grow with different rates and transform into the resting state depending on the concentration of the substrate consumed by both subpopulations. The slow-growing subpopulation is assumed to be motile. In numerical simulations it is shown that this subpopulation is able to overgrow the other one. The dominance phenomenon (resulting from random cell motion) depends on the motility coefficient in a threshold manner: in a heterogeneous tumour the slow-dividing motile subpopulation is able to overgrow its non-motile counterparts if its motility coefficient exceeds a certain threshold value. Computations demonstrate independence of the motile cells overgrowth from the initial tumour composition.

Performance Enhancement of Pneumatic Vibration Isolators Using Self-Tuning PID Feedback and Time-Delay-Control (TDC)-Based Feedforward Scheme

2018 ◽  
Author(s):  
Jin-Wei Liang ◽  
Hung-Yi Chen ◽  
Lyu-Cyuan Zeng
Keyword(s):  
Mathematical Model ◽  
Performance Enhancement ◽  
Control Method ◽  
Hybrid Control ◽  
Model Performance ◽  
Experimental Investigations ◽  
Isolation System ◽  
Control Scheme ◽  
Self Tuning ◽  
Hybrid Control Scheme

A hybrid control scheme that combines a self-tuning PID-feedback loop and TDC-based feedforward scheme is proposed in this study to cope with an active pneumatic vibration isolator. In order to establish an effective TDC feedforward control a reliable mathematical model of the pneumatic isolator is required and developed firstly. Numerical and experimental investigations on the validity of the mathematical model are performed. It is found that although slight discrepancy exists between predicted and observed behaviors of the system, the overall model performance is acceptable. The resultant model is then applied in the design of the TDC feedforward scheme. A neuro-based adaptive PID control is integrated with the TDC feedforward algorithm to form the hybrid control. Numerical and experimental isolation tests are carried out to examine the suppression performances of the proposed hybrid control scheme. The results show that the proposed hybrid control method outperforms solely TDC feedforward while the latter outperforms the passive isolation system. Moreover, the proposed hybrid control scheme can suppress the vibration near the system’s resonance.

Influence of a delamination on Lamb wave excitation by a nearby piezoelectric transducer

2020 ◽  
pp. 1045389X2091997 ◽  
Author(s):  
Alisa N Shpak ◽  
Mikhail V Golub ◽  
Inka Mueller ◽  
Artem Eremin ◽  
Jens Kathol ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Piezoelectric Transducer ◽  
Lamb Wave ◽  
Lamb Waves ◽  
Boundary Integral ◽  
Experimental Investigations ◽  
Wave Excitation ◽  
Damage Scenarios ◽  
Active Sensor ◽  
Piezoelectric Wafer

This article presents the results of theoretical and experimental investigations of characteristic changes of Lamb wave excitation and scattering by a strip-like horizontal delamination in a layered elastic waveguide for Lamb waves induced by a piezoelectric wafer active sensor. The boundary integral equation method is used to describe wave propagation in an infinite layered waveguide with a delamination, while the frequency domain spectral element method is employed to model the dynamic behaviour of the piezoelectric wafer active sensor, which allows to simulate debonding between the piezoelectric wafer active sensor and the waveguide. Experimental investigations of the dynamic interaction of the piezoelectric wafer active sensor with a layered plate containing a horizontal delamination is conducted for several damage scenarios, showing a good agreement with the results obtained using the developed mathematical model. The obtained mathematical model is employed to analyse alteration of the piezo-induced Lamb waves including modes’ decomposition due to delamination. The conversion and/or conservation of the Lamb waves on account of a delamination is investigated. The electro-mechanical impedance of the piezoelectric transducer and the stress intensity factors of a delamination are analysed in dependence on the delamination location.

scholarly journals Modeling of Pressure Drop During Refrigerant Condensation in Pipe Minichannels

2017 ◽  
Vol 38 (4) ◽  
pp. 15-28 ◽  
Author(s):  
Małgorzata Sikora ◽  
Tadeusz Bohdal
Keyword(s):  
Mathematical Model ◽  
Pressure Drop ◽  
Computer Modeling ◽  
Experimental Verification ◽  
Flow Resistance ◽  
Experimental Results ◽  
Experimental Investigations ◽  
Flow Conditions ◽  
Conservation Equations ◽  
Mathematical And Computer Modeling

Abstract Investigations of refrigerant condensation in pipe minichannels are very challenging and complicated issue. Due to the multitude of influences very important is mathematical and computer modeling. Its allows for performing calculations for many different refrigerants under different flow conditions. A large number of experimental results published in the literature allows for experimental verification of correctness of the models. In this work is presented a mathematical model for calculation of flow resistance during condensation of refrigerants in the pipe minichannel. The model was developed in environment based on conservation equations. The results of calculations were verified by authors own experimental investigations results.

INVESTIGATION OF BULK MATERIAL MOTION IN SPIRAL SIEVES

2021 ◽  
Vol 2021 (2) ◽  
pp. 4-12
Author(s):  
Evgeniya Belokur ◽  
Aleksandr Sekisov ◽  
Georgiy Serga
Keyword(s):  
Mathematical Model ◽  
Process Development ◽  
Bulk Material ◽  
Experimental Investigations ◽  
Complex Method ◽  
Longitudinal Motion ◽  
Experimental Plant ◽  
Model Choice ◽  
Material Particle ◽  
Material Separation

The work purpose is to increase the productivity of bulk material separation by means of engineering process development based on fundamentally new engineering equipment in the form of spiral sieves, the novelty of which is confirmed by six patents for invention of the Russian Federation. In the work there was used a complex method of investigations. Analytical methods allowed offering dependences for the definition of bulk material longitudinal motion speed in spiral sieves. Experimental investigations were carried out in order to confirm analytical dependences. The analytical investigation of bulk material separation into fractions for the purpose of conditional model choice for its description is presented. A mathematical model choice is fulfilled. There is analyzed a model of continuous medium and that of a material particle. A mathematical model is developed to determine a speed of longitudinal motion of bulk material from charging to unloading. There is presented not only a circuit and an experimental plant created in metal version, but the results of experimental investigations of bulk medium motion parameters subject to spiral sieve design peculiarities are shown which presented a coincidence level high enough.

scholarly journals Numerical analysis of heat transfer in air-water heat exchanger with microchannel coil

2019 ◽  
Vol 95 ◽  
pp. 02004
Author(s):  
Vladimir Glazar ◽  
Anica Trp ◽  
Kristian Lenic ◽  
Fran Torbarina
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Fluid Flow ◽  
Heat Exchanger ◽  
Numerical Analysis ◽  
Flow Direction ◽  
Heat Fluxes ◽  
Experimental Investigations ◽  
Flow And Heat Transfer ◽  
Working Parameters

This paper presents numerical analysis of fluid flow and heat transfer in the heat exchanger with microchannel coil (MCHX). In accordance with previously published experimental results, 3D mathematical model has been defined and appropriate numerical simulation of heat transfer has been performed. Geometry and working parameters of cross-flow air-water heat exchanger with microchannel coil, installed in an open circuit wind tunnel and used in experimental investigations, have been applied in numerical analysis in order to validate the mathematical model. 3D model with air and water fluid flow and heat transfer domains has been used, as it gives more precise results compared to models that assume constant temperatures or constant heat fluxes on the pipe walls. Developed model comprised full length of air and water flows in the heat exchanger. Due to limitations of computational capacity, domain has been divided in multiple computational blocks in the water flow direction and then solved successively using CFD solver Fluent. Good agreement between experimentally measured and numerically calculated results has been obtained. The influence of various working parameters on heat transfer in air-water heat exchanger has been studied numerically, followed with discussion and final conclusions.

Investigation of Dynamic Processes in Ball Bearings with Defects

2013 ◽  
Vol 198 ◽  
pp. 651-656 ◽  
Author(s):  
Marijonas Bogdevičius ◽  
Viktor Skrickij
Keyword(s):  
Mathematical Model ◽  
Ball Bearing ◽  
Dynamic Processes ◽  
Experimental Investigations ◽  
Ball Bearings ◽  
Outer Race ◽  
Rolling Element ◽  
Inner Race

The paper considers the dynamics of ball bearings with defects. A mathematical model of a ball bearing with defects is offered. The performed theoretical and experimental investigations of ball bearings with defects are described. Five cases of various defects are investigated, including the defective outer race, the defective inner race, the defective rolling element, the defective inner and outer races, the rolling element and a separator, the worn-out ball bearing.

Infrasound and Low Frequency Noise in the Passenger Compartment of Vehicles

1997 ◽  
Vol 16 (4) ◽  
pp. 219-227 ◽  
Author(s):  
Helmut Spannheimer ◽  
Raymond Freymann
Keyword(s):  
Mathematical Model ◽  
Low Frequency ◽  
Experimental Investigations ◽  
Frequency Noise ◽  
Simple Mathematical Model ◽  
Low Frequency Noise ◽  
Acoustic Response ◽  
Frequency Range ◽  
Passenger Compartment

The acoustic response determined in the passenger compartment of a vehicle is characterized by resonances in the infrasound and low frequency range. A simple mathematical model is derived allowing the numerical identification of the related low frequency acoustic eigenmodes. The numerically obtained results are verified on the basis of experimental investigations.

The Modulation of Chatter Vibrations

1969 ◽  
Vol 91 (3) ◽  
pp. 673-677 ◽  
Author(s):  
R. A. Thompson
Keyword(s):  
Mathematical Model ◽  
Vibrational Frequency ◽  
Machining Process ◽  
Experimental Investigations ◽  
Characteristic Frequencies ◽  
Chatter Vibrations ◽  
Machining Chatter

The results of several experimental investigations concerning the nature of machining chatter are discussed. They indicate that chatter vibrations are generally amplitude modulated and that the chatter frequency may or may not vary from the free vibrational frequency of the chattering component. Of the several results considered each is explained in terms of an extension of the empirically derived lag equation for the machining process of Doi and Kato whereby the characteristic frequencies of the lag equation are determined. The fact that the frequency related phenomena of several independent tests are confirmed by the lag equation, which was not derived from frequency considerations, seems to justify it as a valid mathematical model for the machining process.

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