Time-domain simulations of stringed and percussion instruments

Integrals that are of interest in the analysis, design, and optimization of concentrating solar thermal systems (CST), such as the annual optical efficiency of the light collection and concentration (LCC) subsystem, can be accurately computed or estimated in two distinct ways: on the time domain and on the spatial domain. This article explores these two ways, using a case study that is highly representative of the commercial CST systems being deployed worldwide. In the time domain, the computation of these integrals are explored using 1-min, 10-min, and 1-h solar DNI input data and using The Cyprus Institute (CyI)’s High-Performance Computing (HPC) system and an open-source ray tracer, Tonatiuh++, being actively developed at CyI. In the spatial domain, the computation of these integrals is explored using SunPATH, another open-source software tool being actively developed at CyI, in tandem with Tonatiuh++. The comparison between the time and spatial domain approach clearly indicate that the spatial domain approach using SunPATH is dramatically more computationally efficient than the time domain approach. According to the results obtained, at least for the case study analyzed in this article, to compute the annual energy delivered by the LCC subsystem with a relative error less than 0.1%, it is enough to provide SunPATH with 1-h DNI data as input, request from SunPATH the sun position and weights of just 30 points in the celestial sphere, and run Tonatiuh++ to simulate these 30 points using 15 million rays per run. As the test case is highly representative, it is expected that this approach will yield similar results for most CST systems of interest.

In this current paper, we purpose a ferrielectric mixed (7/2;2) spins Ising model to describe the dendrimer superlattice using Monte Carlo study (MCs). The ground state phase diagrams of dendrimer superlattice with half and integer mixed spins in (DS, EZ ), (JσS, EZ ) and (JσS, DS ) planes (DS (or σ): crystal field and Ez : Electric field) were obtained. Typical temperature dependences of thermodynamics quantities such as polarisation of the ferroelectric, internal energy and ferroelectric hysteresis loop were presented under the influence of various physical parameters (crystal filed, exchanges interactions, etc.). The ferroelectric phase diagram of critical temperature was obtained for several exchange interactions. We found some interesting ferroelectric hysteresis loops behaviour for certain physical parameters such as temperature, exchange interactions between spins mixed and crystal field applied on two spins. Our results are consistent with those obtained by some theoretical and experimental researches.

Third order time and frequency analysis has exhibited great potential for correlation analysis of multi-sensor datasets, but is usually presented as separate time domain and frequency domain approaches. A combined framework of both frequency domain and time domain has rarely been used. This paper proposes a non-parametric third order time and frequency domain framework which used two dimensional Fourier transforms to bridge the gap between time domain and frequency domain. A unified framework offers flexibility and efficiency to apply to data. In this paper we study neural spike train data treated as stochastic point processes. In time domain direct analysis, third order cumulant densities of spike trains are applied, which need all first-, secondand third order product densities to be calculated before constructing the third order cumulant density, which brings additional challenges. The novelty in this study is that a new framework is proposed which can offer an alternative approach without calculating lower order quantities and can reveal nonlinear relationship between neural recordings. The results show that the present framework provides a novel non-parametric method to estimate both time and frequency domain measurements which is applicable to neural spike trains.

A percussive sound contains both harmonic and non-harmonic frequency spectral content. To reproduce a particular percussive sound, such as the sound of a drum or cymbal or hand clap, for example, the harmonic and non-harmonic content are determined empirically. Also, and tendency of the harmonic content to change over time, and the temporal aspects of attack, sustain, and decay are likewise determined empirically. These attributes are represented in the invention in a percussive sound file which includes a harmonic content profile ( 502 ), noise shape filter ( 504 ), Doppler shift profile ( 506 ), and a time wave shaping profile ( 508 ). The harmonic content profile is used by an FM generator ( 114 ) to generate a frequency modulated signal ( 116 ). The noise shape profile is used by a noise generator ( 134 ) to generate and shape the non-harmonic spectral content. While the sound is being generated, the Doppler shift profile is used to adjust the base frequency of the FM signal. The harmonic and non-harmonic signals are scaled ( 142, 144 ) and summed ( 146 ). The summed signal is then shaped ( 150 ) in time to substantially simulate the attack, sustain, and decay properties of the sound. The shaped, summed signal is then played by an audio circuit and converted to an acoustic signal.

This paper numerically studied heat and mass transfer flow of Casson nanofluid near to the stagnation point due to the stretching sheet with the effects of viscous dissipation, space-dependent, and temperature-dependent heat source/sink. By using similarity transformations, the governing equations of the flow problem are converted into non-linear ordinary differential equations. The resulting obtained ODE'S are solved numerically by the Keller Box method. Analyzed the influence of various physical parameters on the velocity, temperature and concentration distributions shown graphically. Present results are compared with previously published work and results are found to be a very good agreement. The velocity profile decreases with an increase in the Casson parameter and magnetic parameter. Temperature profile increases with an increase in the Casson parameter, thermophoresis parameter, Brownian motion parameter, Eckert number, space dependent internal heat source/sink, and temperature-dependent internal heat source/ sink parameters increase, while a decrease in Prandtl number. Concentration profile increases with increase Casson parameter and thermophoresis parameter.

PurposeThe present investigation aims to deal with the study of unsteady, heat-generating/-absorbing and chemically reacting Casson fluid flow over a vertical cone and flat plate saturated with non-Darcy porous medium in the presence of cross-diffusion effects.Design/methodology/approachA numerical computation for the governing equations has been performed using implicit finite difference method of Crank–Nicolson type.FindingsThe influence of various physical parameters on velocity, temperature and concentration distributions is illustrated graphically, and the physical aspects are discussed in detail. Numerical results for average skin-friction, Nusselt number and Sherwood number are tabulated for the pertaining physical parameters. Results indicate that Soret and Dufour effects have notable influence on heat and mass transfer characteristics of the fluid when the temperature and concentration gradients are high. It is also observed that the consideration of heat generation/absorption plays a vital role in predicting the heat transfer characteristics of moving fluids.Research limitations/implicationsConsider a two-dimensional, unsteady, free convective flow of an incompressible Casson fluid over a vertical cone and a flat plate saturated with non-Darcy porous medium. The fluid properties are assumed to be constant except for density variations in the buoyancy force term. The fluid flow is moderate and the permeability of the medium is assumed to be low, so that the Forchheimer flow model is applicable.Practical implicationsThe flow of Casson fluids (such as drilling muds, clay coatings and other suspensions, certain oils and greases, polymer melts and many emulsions), in the presence of heat transfer, is an important research area because of its relevance in the optimized processing of chocolate, toffee and other foodstuffs.Social implicationsIn the heat and mass transfer investigations, the Casson fluid model is found to be accurately applicable in many practical situations in the wings of polymer processing industries and biomechanics, etc.; some prominent examples are silicon suspensions, suspensions of bentonite in water and lithographic varnishes used for printing inks.Originality/valueThe motivation of the present study is to bring out the effects of heat source/sink, Soret and Dufour effects on chemically reacting Casson fluid flow over a vertical cone and flat plate saturated with non-Darcy porous medium. The flow of Casson fluids (such as certain oils and greases, polymer melts and many emulsions) in the presence of heat transfer is an important research area because of its relevance in the optimized processing of chocolate, toffee and other foodstuffs. A numerical computation for the governing equations has been performed using implicit finite difference method of the Crank–Nicolson type.

The boundary layer flow of an incompressible viscoelastic Jeffrey’s nanofluid from a vertical permeable flat plate is investigated. We consider the effects of heat generation, thermal radiation, and chemical reaction on the fluid flow. The nonlinear transformed coupled differential equations that describe the transport processes are solved numerically using a multidomain bivariate spectral quasilinearization method (MD-BSQLM). This innovative method involves blending the quasilinearization idea with the bivariate Lagrange interpolation. The solutions of the resulting system of equations are then obtained sequentially on multiple intervals using the Chebyshev spectral collocation method. The method is shown to give accurate solutions for boundary layer-type equations. The influence of various physical parameters on velocity, temperature, and nanoparticle concentration fields, as well as on the skin friction and heat and mass transfer coefficients, is shown and discussed in detail. The range of the values of the governing parameters considered in this study is between 0 , 4 . For qualitative validation of the results and the numerical method used, calculations were carried out to graphically obtain the velocity, temperature, and nanoparticle concentration fields for selected physical parameter values. The results obtained were found to correlate with the results from published literature. For quantitative verification of our findings, the MD-BSQLM numerical solutions were again confirmed against published results reported in the literature, and the results were observed to be in perfect agreement. This study’s findings indicate that the Deborah number and suction parameter have related effects on the velocity profile, which is to suppress both the flow velocity and the momentum boundary layer thickness. Increasing the heat generation and thermal radiation parameters enhances both the temperature and thermal boundary layer depths. In contrast, an increase in the chemical reaction parameter causes a decrease in the fluid concentration.

Tissue characterization by endoscopic fluorescence imaging of endogenous or exogenous fluorochromes is a promising method for early cancer detection. However, the steady-state fluorescence contrast between healthy tissue and lesions such as early-stage carcinomas is generally poor. The authors propose to improve this contrast by using the additional information contained in the fluorescence lifetime (FLT). The FLT of several fluorochromes is sensitive to their physico-chemical environment.The FLT can be measured by frequency-domain methods. The excitation light from a continuous wave (CW) laser is modulated in amplitude at radio-frequencies by an electro-optic modulator, and delivered to the tissue via an optical fibre. The endoscopie site is imaged by an endoscope on to an optical device. The gain of the fluorescence image detector is also modulated at the same frequency for homodyning. The tissue fluorescence image is recorded at several phases between the excitation and the detection modulations during an acquisition cycle. With these images, an image processor calculates the apparent FLT for each pixel and constructs a lifetime image of the endoscopie site. This process is performed at quasi-video frequencies.The influence of various physical parameters (modulation frequency, number of images by cycle, shot noise, tissue optical properties etc.) has been investigated by analytical analysis, simulation methods and experimentation.Preliminary results obtained on human tissues are also presented to illustrate the potentiality of the method.

This manuscript documents the alteration of the heart model of the three-dimensional (3D) mathematical cardiac torso (MCAT) phantom to represent cardiac motion. The objective of the inclusion of motion was to develop a digital simulation of the heart such that the impact of cardiac motion on single-photon emission computed tomography (SPECT) imaging could be assessed and methods of quantitating cardiac function could be investigated. The motion of the gated 3D MCAT's (gMCAT) heart is modeled using 128 separate and evenly spaced time samples from a blood volume curve approximating an average heart cycle. Sets of adjacent time samples can be grouped together to represent a single time interval within the heart cycle. Maximum and minimum chamber volumes were selected to be similar to those of a normal healthy person while the total heart volume stayed constant during the cardiac cycle. Myocardial mass was conserved during the cardiac cycle and the bases of the ventricles were modeled as moving towards the static apex. The orientation of the 3D MCAT heart was changed during contraction to rotate back and forth around the long axis through the center of the left ventricle (LV) using the end systolic time interval as the time point at which to reverse direction. Simple respiratory motion was also introduced by changing the orientation of the long axis of the heart to represent its variation with respiration. Heart models for 24 such orientations spanning the range of motion during the respiratory cycle were averaged together for each time sample to represent the blurring of the heart during the acquisition of multiple cardiac cycles. Finally, an option to model apical thinning of the myocardium was included. As an illustration of the application of the gMCAT phantom, the gated heart model was evaluated by measuring myocardial wall thickening. A linear relationship was obtained between maximum myocardial counts and myocardial thickness, similar to published results. Similar results were obtained for full width at half maximum (FWHM) measurements. With the presence of apical thinning, an apparent increase in counts in the apical region compared to the other heart walls in the absence of attenuation compensation turns into an apparent decrease in counts with attenuation compensation. The apical decrease was more prominent in end systole (ES) than end diastole (ED) due to the change in the partial volume effect. These observations agree with clinical trends. It is concluded that the gMCAT phantom can be used to study the influence of various physical parameters on radionuclide perfusion imaging.

Smart Materials for Sensing

The present study is devoted to the flow and heat transfer analysis of the hyperbolic tangent fluid through a stretching sheet by considering the effect of thermal radiation in addition to an applied transverse magnetic field, as well as thermal and velocity slip conditions. The Lie group analysis technique has been utilized for establishing similarity transformations, which effectively transform the governing equations to a system of nonlinear ordinary differential equations (ODEs). These ODEs are numerically solved by utilizing the shooting method. The heat transfer properties and flow features under the influence of various physical parameters are also studied. We noted that by increasing the thermal radiation parameter, the temperature profile increases and also the thermal boundary layer thickens. Furthermore, it is deduced that rising the thermal radiation parameter reduces the local Nusselt number. Moreover, the numerical results obtained are in agreement with the existing results in the literature.

This study investigates the impact of magnetohydrodynamics (MHD) on steady natural convection Couette flow of a heat generating/absorbing fluid in a vertical channel in the presence of viscous dissipation. The dimensionless governing equations for momentum and energy were analytically solved using the Homotopy perturbation method. The influence of various physical parameters on the flow behavior is illustrated through graphical results. Moreover, the effects of these parameters on skin friction, rate of heat transfer, mass flux and mean temperature are analyzed and presented numerically in tabular form. Findings from the study show that, the magnetic field intensity on the velocity and temperature distributions of the fluid. It is worth highlighting that increasing the permeability enhances the fluid velocity and also the temperature near the heated plate rises, while a steeper temperature gradient is observed across the channel. Increasing the Eckert number significantly enhances both fluid velocity and temperature. The findings of this study are important due to its application in magnetohydrodynamics Power Generation, Metallurgy and Materials Processing, Cooling Systems in Nuclear Reactors, Electromagnetic Pumps, Plasma Propulsion and Aerospace and Food and Chemical Industries.

The dynamics of light bullets propagating in nonlinear media with linear/nonlinear, gain/loss and coupling described by the (2+1)-dimensional vectorial cubic–quintic complex Ginzburg–Landau (CGL) equations is considered. The evolution and the stability of the vector dissipative optical light bullets, generated from an asymmetric input with respect to two transverse coordinates x and y, are studied. We use the variational method to find a set of differential equations characterizing the variation of the light bullet parameters in the laser cavity. This approach allows us to analyze the influence of various physical parameters on the dynamics of the propagating beam and its relevant parameters. Then, we solve the original coupled (2+1)D cubic–quintic CGL equation using the split-step Fourier method. Numerical results and analytical predictions are confronted, and a good agreement between the two approaches is obtained.

Purpose The purpose of this study is to investigate the influence of various physical parameters on the flow and heat transfer characteristics of a porous moving cylinder embedded in a porous medium filled with a biomagnetic nanofluid. The selected nanofluid comprises CoFe2O4 nanoparticles dispersed in human blood, which is relevant to biomedical applications such as targeted drug delivery, hyperthermia therapy and blood flow simulation. Design/methodology/approach Mathematical modeling is employed to describe the magnetohydrodynamic (MHD) nanofluid flow under prescribed surface temperature (PST), prescribed surface concentration (PSC) and prescribed surface microorganism (PSM) boundary conditions. Similarity transformations are applied to convert the governing partial differential equations into ordinary differential equations, which are solved analytically using hypergeometric Kummer functions. Response Surface Methodology (RSM) is also utilized to develop a quadratic regression model for the Nusselt number in terms of the Hartmann, Darcy and Eckert numbers. Findings The results show that chemical reaction and gyrotactic microorganism parameters reduce concentration and microorganism distributions. Hartmann and Darcy numbers decrease the Nusselt number, while the Eckert number enhances it. Furthermore, the local skin friction coefficient increases with the Darcy number. Originality/value This study provides new analytical insights into biomagnetic nanofluid flow over a moving porous cylinder subject to multiple boundary conditions. The outcomes advance understanding relevant to the design and optimization of biomedical devices and diagnostic systems based on magneto-fluidic principles.

Pulse propagating in inhomogeneous nonlinear media with linear/nonlinear gain and loss described by the asymmetrical (2 + 1)-dimensional cubic-quintic Ginzburg-Landau equation is considered. The evolution and the stability of the dissipative optical solitons generated from an asymmetric input with respect to two transverse coordinates x and y are studied. Our approach is based on the variational method. This approach allows us to analyze the influence of various physical parameters on the dynamics of the propagating signal and its relevant parameters. According to the parameters of the system and a suitable choice of the test function, a domain of dissipative parameters for stable solitonic solutions is determined. Bifurcation diagrams related to the existence of the stationary solutions presented show a good agreement between analytical and numerical results.