Smart Materials for Sensing

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.

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.

The introduction of smart materials will become increasingly relevant as biomedical technologies progress. Smart materials sense and respond to external stimuli (e.g., chemical, electrical, mechanical, or magnetic signals) or environmental circumstances (e.g., temperature, illuminance, acidity, or humidity), and provide versatile platforms for studying various biological processes because of the numerous analogies between smart materials and biological systems. Several applications based on this class of materials are being developed using different sensing principles and fabrication technologies. In the biomedical field, force sensors are used to characterize tissues and cells, as feedback to develop smart surgical instruments in order to carry out minimally invasive surgery. In this regard, the present work provides an overview of the recent scientific literature regarding the developments in force measurement methods for biomedical applications involving smart materials. In particular, performance evaluation of the main methods proposed in the literature is reviewed on the basis of their results and applications, focusing on their metrological characteristics, such as measuring range, linearity, and measurement accuracy. Classification of smart materials-based force measurement methods is proposed according to their potential applications, highlighting advantages and disadvantages.

With the rapid development of market economy and information technology, some traditional anti-counterfeiting technologies are constantly cracked by lawbreakers. The improvement and transformation of anti-counterfeiting technologies become inevitable, and the emerging anti-counterfeiting technologies continue to move towards greenization, intelligence and popularization. Based on the research status domestic and overseas, the paper not only defined the basic concepts of smart materials, but divided them into four parts including novel nano-materials, stimulus response materials, shape memory materials and other new-type materials. The anti-counterfeiting mechanism and application cases of new nano-ink, nano-structure material and nano-composite were introduced emphatically. The research progress and potential application in anti-counterfeiting areas of stimulus-responsive materials were overviewed briefly from the perspective of inducement factors of light, electricity and magnetism etc. In addition, the basic principle of the anti-counterfeiting labels combined with the shape memory materials was analyzed. Finally, the paper also involved the anti-counterfeiting applications of other intelligent anti-counterfeit materials, such as new card-based material (PHA), functional anti-counterfeiting paper and molding resin, which expanded the application fields of intelligent materials. It concluded that intelligent materials have a broad application in the field of anti-counterfeiting. The paper can provide a powerful theoretical guide for the further application of intelligent materials in anti-counterfeiting.

Photocatalytic efficiency of GO-based Ti-doped Co3O4 nanosheets for mixed dyes and the effects of oxidizing and reducing reagents

In the past decade, 3D/4D printing has emerged as a novel and acceptable approach to manufacturing cost-effective industrial products, sensors, and actuators for various devices. The 4D printing of polymers is now being explored widely for advanced space exploration and biomedical and structural applications by utilizing smart materials that possess shape-memory or programming properties. Commercially available smart materials (ceramics and composite-based) are reportedly costly for the desired applications. Nevertheless, little has been reported on the in-house development of smart materials for such 4D printing applications. The present study highlights the material processing route to prepare smart polymer-based composite materials in lab-scale environments that possess good shape-recovery features (piezoelectric capabilities) and self-alignment capabilities for non-structural engineering-based 4D printing applications. The proposed material processing route may be adopted for self-expansion and self-contraction properties of thermoplastic composites for the replacement of hip joints. Finally, a framework for fabrication of smart/rapid tooling to be used in total hip arthroplasty (THA) (having 4D capabilities) has been detailed in this work.

The development of intelligent materials, i.e. materials that usually have a dramatic and reversible response to one or more external stimuli, is critically reviewed, with emphasis on intelligent fibrous materials. Initial developments and concepts were made with shape-memory metal alloys, followed by polymeric gels, and, more recently, intelligent fibrous materials. Examples of intelligent metals, polymer gels, and fibrous products are presented, and new applications and products based on fibrous intelligent materials are explored.

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.

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 tones of existing instruments are simulated in the time domain by means of standard finite difference methods. The string model previously applied to the guitar [A. Chaigne, J. Acoust. Soc. Am. Suppl. 1 88, S188 (1990)] and more recently to the piano [A. Chaigne, A. Askenfelt, and E. Jansson, J. Acoust. Soc. Am. 89, 1878(A) (1991)] has been extended to the violin, the xylophone bars, and tympani membranes. The general procedure, which is similar for each type of instrument, will be presented. It consists first in deriving a numerical scheme from the continuous differential equations governing the motion of the vibrating systems including the interaction with an exciter (hammer, bow, mallets,...). In a second step, the mathematical properties of these discrete approximations are evaluated with special emphasis laid on stability, accuracy, and dispersion problems. Simulated waveforms are computed with realistic values of the parameters derived from measurements on existing instruments. These waveforms as well as their spectral contents are then systematically compared with those of real tones. This time-domain approach is used in order to test the influence of various physical parameters on the transients of strings and percussive sounds in which the nonlinear effects are essential. The paper will be illustrated by sound synthesis examples of various instruments obtained with this technique.