Differential Setup Research Articles

Thermofluidic transport of Williamson flow in stratified medium with radiative energy and heat source aspects by machine learning paradigm

This study investigates Williamson fluid with stratification aspects through an inclined medium with radiative effects and with consideration of transversally applied magnetic field. Additionally, the study involves novel contribution of thermal generating source and chemically reactive species. Modelling is conceded by incorporating conservation laws in view of ordinary differential setup after employing similar variables. Afterwards, numerical simulations through shooting and Rk-4 procedures are executed to inspect the behavior of flow and thermosolutal distributions versus variation in key parameters. Subsequently, the collected data is evaluated by utilizing a multilayer perceptron-based ANN model. The input data for the heat flux, corresponding to different fluid model parameters, is trained by employing Levenberg-Marquardt paradigm and validated against numerical experiment results. The precision of the predicted data is assessed by calculating the mean squared error, determination coefficient and error rating scale. The magnitude of heat flux coefficient elevates up to 15 % in the existence of radiation effect, while depreciates up to 6 % in the presence of stratification effect. The implementation of ANN model depicts a mean square error value 1.36×10−3 when no heat source, which rises to 1.41×10−2 when a heat source is present. From small values of mean squared error for testing, training and validation estimated for Nusselt number ensures the performance of developed ANN network.

A case study on effect of variable viscosity on non-newtonian nanofluid over an extendable cylindrical surface by utilizing Reynold’s model

Current artifact aims to investigate attributes of nanofluidic transport mechanism developed for dynamics of Williamson liquid over an extendable cylinder with novel physical aspects of magnetic field. Additionally, Newtonian heating is accounted at cylinder surface and Reynold viscosity model is implemented to delineate the aspects of temperature dependent viscosity. Thermophoresis, Brownian motion, and variable viscosity effects have been studied for heat and mass transfer analysis. Formulation of problems characterized by governing physical laws is conceded in the form of dimensional partial differential setup by executing boundary layer approach. Conversion of attained differential system into ODE’s is engrossed by capitalizing similarity transformations. Numerical procedures (Runge-Kutta and shooting) are implemented to resolve the problem and to attain solution. Effectiveness of sundry variables on associated distributions is revealed through graphical and tabular manner. Quantities of interest are also manipulated against the involved variables. Comparison of results to certify the numerical code is checked by making assessment with existing studies and found remarkable agreement.

Investigation and development of programmable system on chip based differential scanning calorimeter for thermal analysis of materials.

A differential scanning calorimeter was designed to study the thermal analysis of the materials for the nuclear reactor/allied facilities. The hardware and software were developed for measuring the calorimetric signals and had various features for the thermal analysis of the material. The processing of calorimetric signals was carried out by a programmable system-on-chip. Using a programmed temperature profile, the differential scanning calorimeter setup was tested, calibrated, and validated with standard aluminum and indium metal samples. It was found that the obtained results agree with the literature values. The methodology for the experiment was optimized. Various experiments were carried out, and the thermal analysis of different materials for nuclear reactors was investigated and studied. The instrumentation is also compact, accurate, reliable, and cost-effective for the thermal analysis of materials.

Heat transfer augmentation and entropy generation minimization by employing synergistic aspects of hybrid (Fe3O4 + MWNTs) nanoliquid in star shaped enclosure with thermally conductive cylinder and inclined magnetic field aspects

This article aims to simulate optimum thermal convection and minimization in entropy generation in viscous hybrid nanofluid (Fe3O4-MWNTs/H2O) flow in thermally cold star shaped enclosure and containing heated cylinder. Shape effect of cylinder in managing associated hydrothermal attributes is also interrogated. Physical aspect of magnetic field making angle of inclination with domain is accounted. Formulation of transport equations is expressed in the form of dimensionless partial differential setup containing the thermophysical relations of induced hybrid nanoparticles. The constructed flow issue has been simulated by using Galerkin finite element method (G-FEM) with appliance of COMSOL Multiphysics®software computer package.Results and grid convergence assessment tests are also executed in the study. Significant impact of flow controlling parameters on velocity, temperature and entropy generation profiles has been presented in graphical and tabular manner. Variation is three different types of entropies namely, viscous, thermal and magnetic are estimated. Quantities of interest like, total entropy, average Nusselt and Bejan numbers are also calculated against the sundry parameters. Ecological coefficient of performance which measures the efficiency of physical systems is interrogated which is important physical quantity in practical problems. It is inferred from the outcomes that induction of hybrid nanoparticles (Fe3O4 − MWCNT) produces considerable augmentation of thermal attributes of base fluid. Moreover, it is depicted that average Nusselt number exceeds up to 26.5 % for star shaped inner cylinder in comparison to the square cylinder. Increment up to 6 % in average Nusselt number and 2.19 % decrease in entropy is depicted when hybrid nanoparticles are added in the base fluid (ϕ≠0) in comparison to the situation when nanoparticles are not induced (ϕ=0).

Transport-of-intensity model for single-mask x-ray differential phase contrast imaging

X-ray phase contrast imaging holds great promise for improving the visibility of light-element materials such as soft tissues and tumors. The single-mask differential phase contrast imaging method stands out as a simple and effective approach to yield differential phase contrast. In this work, we introduce a model for a single-mask phase imaging system based on the transport-of-intensity equation. Our model provides an accessible understanding of signal and contrast formation in single-mask x-ray phase imaging, offering a clear perspective on the image formation process, for example, the origin of alternate bright and dark fringes in phase contrast intensity images. Aided by our model, we present an efficient retrieval method that yields differential phase contrast imagery in a single acquisition step. Our model gives insight into the contrast generation and its dependence on the system geometry and imaging parameters in both the initial intensity image as well as retrieved images. The model validity as well as the proposed retrieval method are demonstrated via both experimental results on a system developed in house as well as Monte Carlo simulations. In conclusion, our work not only provides a model for an intuitive visualization of image formation but also offers a method to optimize differential phase imaging setups, holding tremendous promise for advancing medical diagnostics and other applications.

To be or not to be a hydrophobic matrix? the role of coating hydrophobicity on anti-icing behavior and ions mobility of ionic liquids

The demand for anti-icing coatings to endure extremely low temperatures is substantial. Despite the innovative pioneering research on the anti-icing potential of ionic liquids (ILs), the development of such coatings is still in its infancy. Our study investigates how matrix hydrophobicity influences mobility of ILs at subzero temperatures and, consequently, their anti-icing behavior. Wettability results highlight the key role of IL anion hydrophobicity. Dielectric spectroscopy distinguishes ion mobility in the coatings at low temperatures. We also investigate how varying crosslink density affects ion mobility by measuring the water absorbency. Higher mobility of released ILs from the coatings at subzero was confirmed by their presence in water solutions, validated with UV–vis spectroscopy, and resulted in increased ionic conductivity. Differential scanning calorimetry and experimental setups were employed to assess ice formation temperature, time, and ice adhesion strength. Notably, surfaces containing IL exhibited a remarkable reduction in ice formation temperature to –23.5 ℃ and achieved an exceptionally low ice adhesion strength (∼15 kPa), attributed to the formation of a quasi-liquid layer (QLL). Solid-state NMR spectroscopy provided confirmation of the existence of QLL at the interface. Ice adhesion strength of coatings was examined against accelerated weathering, icing/de-icing cycles, as well as endurance against frost formation under freeze–thaw. Our findings underscore the significance of selecting the right matrix with regards to hydrophobicity and ILs when designing coatings for subfreezing applications.

Monitoring of the Enzymatic Reactions Course by Differential Microwave Dielectrometry Method in Real Time

Enzymatic reactions are the basis of many biotechnological manufacturing and biomedical diagnostic procedures that require effective methods of monitoring over the reaction course. In the current paper, we present the results of the development of a new approach within the differential microwave dielectrometry method for the non-invasive monitoring of the course of enzymatic reactions based on the complex permittivity changes of these reactive mixture solutions in real time at a fixed frequency of 31.82 GHz. The dynamic studies of the dielectric parameters of selected enzymatic systems containing a protein substrate (immunoglobulin G, human serum albumin) and enzyme trypsin. The developed differential microwave dielectrometry setup has been performed to verify the proposed approach effectiveness for the enzymatic reaction monitoring in biomedical practice and the food industry. Our microwave dielectrometry results have been validated by the results of the UV-Vis spectrophotometry method for selected enzymatic systems. We propose a new approach to use the differential microwave dielectrometry method with high sensitivity (in average 0.5% and 3÷5% for the real and imaginary parts of the complex permittivity, respectively) to estimate the course of enzymatic reactions in real time.

Magnetized flow of naturally convective viscous fluid in permeable rhombus-shaped annulus by executing FEM simulations

The present work is deliberated to investigate the flow and thermal behavior of viscous fluid flow in permeable rhombic-shaped enclosure. Annular region lying below inner and outer rhombuses is the area of concentration during this study. Magnetic field is employed in horizontal direction to envision aspects of Lorentz field. Governing equations are developed in dimensional form of partial differential setup. Numerical experiments via finite element approach are capitalized to find solution. Grid convergence test is executed to show domain distribution along with decision about mesh level at which computations are to conducted. Streamlines and isothermal maps are sketched to show comprehensive change in associated flow fields against governing parameters. Kinetic energy and average heat flux coefficient are evaluated in comparative manner for magnetic and hydrodynamic situations. Through attained outcomes, it is concluded that kinetic energy and heat flux coefficient enhances reduction against Hartmann number.

Study of the passive method of induced polarization at the copper deposit “Zhaman-Aibat”

The article presents data from field experimental observations using the passive method of induced polarization, at the Zhomart mine (Zhaman-Aibat deposit, Republic of Kazakhstan) on September 7-8, 2021. Profiling was carried out with a step of 50 meters, non-polarizing electrodes of the “VITR” brand were used as electrodes. The signals were recorded using a specialized precision 24-bit analog-to-digital converter. In the course of field observations, a profile characteristic was obtained in terms of the induced polarization parameter. An analysis of the profiling graph shows that the obtained profile characteristic marks the presence of an ore body with two peaks with values of 0.35 and 0.32, which, when using a three-electrode differential setup, indicates the presence of polarization anomaly boundaries. Thus, the passive method of induced polarization makes it possible to register ore anomalies down to a depth of 600 m and makes it possible to detect copper-bearing ores.

Evaluation of the Current Shunt Influence on the Determined Wideband Accuracy of Inductive Current Transformers

This manuscript presents performed laboratory studies and the analysis of the impact of current shunt values used in the differential connection on the wideband metrological performance of inductive current transformers. Moreover, a comparison of the accuracy of wideband and 50 Hz-type inductive current transformers in the specified frequency range from 50 Hz to 5 kHz is presented. The main factor which may influence the wideband accuracy of inductive current transformers is the phenomenon of self-generation. This causes rapid changes in the accuracy, and simultaneously causes the most positive and the most negative values of current error and phase displacement. To evaluate the metrological performance in the differential measurement setup for higher harmonics of the distorted current, a digital acquisition board was used. Obtained results show that if proper values of current shunt resistance are chosen, such devices may be used to evaluate the wideband accuracy of inductive current transformers. The results indicate that the typical units designed for the transformation of sinusoidal current with a frequency of 50 Hz can achieve a comparable metrological performance to that of the wideband inductive current transformer.

Detection of Marginally Discriminated Ions with Differential Solid Contact Ion-Selective Electrodes

A differential sensor is reported for decreasing the interference from multiple ionic and non-ionic species in droplet-sized samples, hence lowering the detection limit for ions that are particularly hard to measure by conventional ion-selective potentiometry. We believe that the proposed approach represents significant progress beyond state-of-the-art by making the application of ion-selective membranes possible for ions that do not have selective ionophores. Two solid contact ion-selective electrodes (SCISEs) are utilized, which are prepared similarly, except for adding ionophore to one of the membranes. We show experimentally and theoretically that a significant signal is observed only when the analyte ion is present in the sample solution. The dynamic response of the sensor is investigated theoretically by Nernst-Planck-Poisson finite element simulations. Symbolic regression is used to generate human-readable expressions. Differential SCISEs are tested under potentiometric and amperometric conditions. While a large potential response is seen in the conventional SCISE vs reference electrode setup at high concentrations of interfering ions, the signal of interfering species is eliminated in the differential SCISE setup. Consequently, it is possible to measure a few μM levels of ammonium in droplets without the interference of potassium using an ionophore that is not especially selective for ammonium over potassium.

An Enzyme-Based Interdigitated Electrode-Type Biosensor for Detecting Low Concentrations of H2O2 Vapor/Aerosol

This work introduces a novel method for the detection of H2O2 vapor/aerosol of low concentrations, which is mainly applied in the sterilization of equipment in medical industry. Interdigitated electrode (IDE) structures have been fabricated by means of microfabrication techniques. A differential setup of IDEs was prepared, containing an active sensor element (active IDE) and a passive sensor element (passive IDE), where the former was immobilized with an enzymatic membrane of horseradish peroxidase that is selective towards H2O2. Changes in the IDEs’ capacitance values (active sensor element versus passive sensor element) under H2O2 vapor/aerosol atmosphere proved the detection in the concentration range up to 630 ppm with a fast response time (<60 s). The influence of relative humidity was also tested with regard to the sensor signal, showing no cross-sensitivity. The repeatability assessment of the IDE biosensors confirmed their stable capacitive signal in eight subsequent cycles of exposure to H2O2 vapor/aerosol. Room-temperature detection of H2O2 vapor/aerosol with such miniaturized biosensors will allow a future three-dimensional, flexible mapping of aseptic chambers and help to evaluate sterilization assurance in medical industry.

Fluid-Structure Interaction of a Foiling Craft

Hydrofoils are a current hot topic in the marine industry both in high performance sailing and in new passenger transport systems in conjunction with electric propulsion. In the sailing community, the largest impact is seen from the America’s cup, where boats are sailed at more than 50 knots (over 100 km/h) with 100% “flying” time. Hydrofoils are also becoming popular in the Olympics, as in the 2024 Olympic games 5 gold medals will be decided on foiling boats/boards. The reason for the increasing popularity of hydrofoils and foiling boats is the recent advances in composite materials, especially in their strength to stiffness ratio. In general, hydrofoils have a very small wetted surface area compared to the wetted surface area of the hull. Therefore, after “take-off” speed, the wetted surface area of the hull, and consequently the resistance of the boat, is reduced considerably. The larger the weight of the boat and crew and the higher the speeds, the greater the loads on the hydrofoils will be. The current research investigates the interaction effects between the fluid and structure of the ZP00682 NACRA 17 Z-foil. The study is carried out both experimentally, in SSPA’s cavitation tunnel, and numerically using a fully coupled viscous solver with a structural analysis tool. The experimental methodology has been used to validate the numerical tools, which in turn are used to reverse engineer the material properties and the internal stiffness of the NACRA 17 foil. The experimental flow speed has been chosen to represent realistic foiling speeds found in the NACRA 17 class, namely 5, 7, and 9 m/s. The forces and the deflection of the Z-foil are investigated, showing a maximum deflection corresponding to 24% of the immersed span. Finally, the effects of leeway and rake angles on the bending properties of the Z-foil are investigated to assess the influence of different angles in sailing strategies, showing that a differential rake set-up might be preferred in search for minimum drag.

On integral and differential formulations in nonlocal elasticity

The paper is concerned with comparative analysis of differential and integral formulations for boundary value problems in nonlocal elasticity. For the sake of simplicity, the focus is on an antiplane problem for a half-space with prescribed shear stress along the surface. In addition, 1D exponential kernel depending on the vertical coordinate is considered.First, a surface loading in the form of a travelling harmonic wave is studied. This provides a counter-example, revealing that within the framework of Eringen’s theory the solution to the differential model does not satisfy the equation of motion in nonlocal stresses underlying the related integral formulation.A more general differential setup, starting from singularly perturbed equations expressing the local stresses through the nonlocal ones, is also investigated. It is emphasised that the transformation of the original integral formulation to the differential one in question is only possible provided that two additional conditions on nonlocal stresses hold on the surface. As a result, the formulated problem subject to three boundary conditions appears to be ill-posed, in line with earlier observations for equilibrium of a nonlocal cantilever beam.Next, the asymptotic solution of the singularly perturbed problem, subject to a prescribed stress on the boundary, together with only one of the aforementioned extra conditions, is obtained at a small internal size. Such simplification may be justified when only one of the stresses demonstrates nonlocal behaviour; a similar assumption has been recently made within the so-called dilatational gradient elasticity. Three-term expansion is obtained, leading to a boundary value problem in local stresses over interior domain. The associated differential equations are identical to those proposed by Eringen, however, the derived effective boundary condition incorporates the effect of a nonlocal boundary layer which has previously been ignored. Moreover, the calculated nonlocal correction to the classical antiplane problem for an elastic half-space, coming from the boundary conditions is by order of magnitude greater than that appearing in the equations of motion. Finally, it is shown that the proposed effective condition supports an antiplane surface wave.

Pricing barrier options with deep backward stochastic differential equation methods

This paper presents a novel and direct approach to solving boundary- and final-value problems, corresponding to barrier options, using forward pathwise deep learning and forward–backward stochastic differential equations (FBSDEs). Barrier instruments are instruments that expire or transform into another instrument if a barrier condition is satisfied before maturity; otherwise they perform like the instrument without the barrier condition. In a partial differential equation, this corresponds to adding boundary conditions to the final-value problem. The deep backward stochastic differential equation (deep BSDE) methods developed so far have not addressed barrier/boundary conditions directly. We extend the pathwise deep BSDE methods to the barrier condition case by adding nodes to the computational graph, in order to explicitly monitor the barrier conditions for each realization of the dynamics, as well as adding nodes that preserve the time, state variables and trading strategy value at the barrier breach, or at maturity otherwise. Given these additional nodes in the computational graph, the forward loss function quantifies the replication of the barrier or final payoff according to a chosen risk measure such as the squared sum of differences. The proposed method can handle any barrier condition in the FBSDE setup and any Dirichlet boundary conditions in the partial differential equation setup, in both low and high dimensions.

AdS graviton stars and differential configurational entropy

AdS graviton stars are studied in the differential configurational entropy setup, as solutions of the effective Einstein field equations that backreact to compactification. With the critical central density of AdS graviton stars, the differential configurational entropy is derived and computed, presenting global minima for a wide range of stellar mass magnitude orders. It indicates insular domains of configurational stability for AdS graviton stars near astrophysical neutron star densities. Other relevant features are also reported.

Full Factorial In Situ Characterization of Ionomer Properties in Differential PEM Fuel Cells

The performance optimization of membrane electrode assemblies of PEM fuel cells requires accurate characterization and modelling of the relevant mechanisms. In this paper, the ionomer conductivities and permeation properties are characterized in situ in a differential cell setup by varying the operating conditions in a full factorial fashion in H2/N2 mode. Voltammetry methods are validated against online gas analysis and then used to record H2 crossover. The membrane and cathode catalyst layer (CCL) resistances are deconvoluted by fitting transmission line models (TLM) to electrochemical impedance spectroscopy (EIS) data. Based on this, we estimate activation energies of 20 kJ mol−1 for the H2 permeation, 7 kJ mol−1 for the membrane resistance and 9 kJ mol−1 for the ionomer resistance in the CCL. Through EIS measurements under load (H2/O2), we also evaluate the change in the ionomer resistances in course of water production. This effect is most pronounced under cold and dry conditions and implies that a subtraction of the protonic loss contributions from polarization curves only based on EIS measurements obtained in H2/N2 mode is not possible.

Absolute calibration of the latent heat of transition using differential thermal analysis.

We describe a simple and accurate differential thermal analysis setup to measure the latent heat of solid state materials undergoing abrupt phase transitions in the temperature range from 77K to above room temperature. We report a numerical technique for the absolute calibration of the latent heat of transition without the need for a reference sample. The technique is applied to three different samples-vanadium sesquioxide undergoing the Mott transition, bismuth barium ruthenate undergoing a magnetoelastic transition, and an intermetallic Heusler compound. In each case, the inferred latent heat value agrees with the literature value within its error margins. To further demonstrate the importance of absolute calibration, we show that the changes in the latent heat of the Mott transition in vanadium sesquioxide (V2O3) remain constant to within 2% even as the depth of supersaturation changes by about 10K in non-equilibrium dynamic hysteresis measurements. We also apply this technique for the measurement of the temperature-dependent specific heat.

Simultaneous Online Monitoring and Sterility Assurance in Aseptic Food Processing Based on a Combined Calorimetric Gas- and Spore-Based Biosensor Array

Introduction Gaseous hydrogen peroxide is one of the most used sterilants for packaging in aseptic filling machines [1]. To validate a sterilization method under investigation, spores (resistant microorganisms against the sterilant) are exposed to the sterilant, the logarithmic kill rate is determined and at the end, the sterilization can be concluded. The main drawback of these methods is their tedious physical work and their slow response; the results can be obtained at the earliest after 24-48 hours. As a result, a novel sensing method has been previously introduced [2] to overcome these issues. In this work, such spore-based biosensor is combined with a calorimetric H2O2 sensor onto single chips to evaluate both the viability of spores and to determine gaseous hydrogen peroxide concentrations. Materials and Methods The calorimetric gas sensor was developed to measure gaseous hydrogen peroxide concentrations. Here, two meander structures were utilized as temperature sensors (see Fig. 1 a), at the bottom part of the sensor chip). One sensor was used as a reference (i.e., inert to H2O2 exposure), whereas the other one was employed as an active element (i.e., functionalized with MnO2 which catalyzes H2O2). As both structures were exposed to H2O2, a temperature increase occurred only at the active sensor. As a result, a temperature difference between both sensors could be correlated to the H2O2concentration. In addition, a spore-based biosensor was fabricated to evaluate the viability of spores. For this, interdigitated electrodes were operated as impedimetric sensors (see Fig. 1 a) at the top part of the sensor chip). A differential setup measurement was used similar like in the calorimetric gas sensor. In this case, spores were immobilized on the active part of the sensor chip. Upon H2O2 exposure, changes in the morphology of the spores aroused, which (by means of impedimetric changes) could be correlated to the viability of spores and hydrogen peroxide concentration. Results and Conclusions The calorimetric gas sensor responds to different concentrations of gaseous hydrogen peroxide (see Fig. 1 b)). The upper curves correspond to the temperature of the catallytically active sensor and the passive one. The temperature difference and accordingly, the actual H2O2 concentration is shown in the lower part curve. In the second experiment, biosensors were investigated with three different strains of bacteria measured at different stages. In the first stage, three biosensors’ impedances were measured after being cleaned. In the second step, B. atrophaeus DSM 675, B. subtilisDSM 402 and G. stearothermophilus DSM 5934 spores were immobilized on them. Finally, the spore-based biosensors were submitted to several concentrations of gaseous hydrogen peroxide. Signal responses (impedance) of the spore-based biosensors at different applied H2O2 concentrations are overviewed in Fig. 1 c).In conclusion, the synergy of these two sensor types as one combined sensor array allows a considerably more specific multi-parameter experience in aseptic filling machines in comparison to isolated microbiological state-of-the-art- or hydrogen peroxide methods.

Low Field Optimization of a Non-Contacting High-Sensitivity GMR-Based DC/AC Current Sensor.

Many applications require galvanic isolation between the circuit where the current is flowing and the measurement device. While for AC, the current transformer is the method of choice, in DC and, especially for low currents, other sensing methods must be used. This paper aims to provide a practical method of improving the sensitivity and linearity of a giant magnetoresistance (GMR)-based current sensor by adapting a set of design rules and methods easy to be implemented. Our approach utilizes a multi-trace current trace and a double differential GMR based detection system. This essentially constitutes a planar coil which would effectively increase the usable magnetic field detected by the GMR sensor. An analytical model is developed for calculating the magnetic field generated by the current in the GMR sensing area which showed a significant increase in sensitivity up to 13 times compared with a single biased sensor. The experimental setup can measure both DC and AC currents between 2–300 mA, with a sensitivity between 15.62 to 23.19 mV/mA, for biasing fields between 4 to 8 Oe with a detection limit of 100 μA in DC and 100 to 300 μA in AC from 10 Hz to 50 kHz. Because of the double differential setup, the detection system has a high immunity to external magnetic fields and a temperature drift of the offset of about −2.59 × 10−4 A/°C. Finally, this setup was adapted for detection of magnetic nanoparticles (MNPs) which can be used to label biomolecules in lab-on-a-chip applications and preliminary results are reported.