Non-uniform Channel Research Articles

Stamping of Nonuniform Channels. 7. Kinematic and Stress State of the Workpiece in Constrained Extrusion. 7.2. Plastic Region under the Punch and Close to the Thick Wall

Stamping of Nonuniform Channels. 7. Kinematic and Stress State of the Workpiece in Constrained Extrusion. 7.2. Plastic Region under the Punch and Close to the Thick Wall

Conditional Entropy-Based Construction of Multilevel Polar-Coded Modulation With Probabilistic Shaping

Code construction is a critical issue for polar-coded systems to ensure competitive performance. In this letter, we propose a conditional entropy-based method to construct multilevel polar-coded modulation (MLC-PCM) with probabilistic shaping. More specifically, we allocate the bit positions in accordance with their conditional entropies induced by channel and source polarization. We show that a surrogate channel can be used to determine the frozen set in each component polar code efficiently. The remaining positions are assigned to the information and shaping bits by the source Bhattacharyya parameter, where the shaping bits are used to achieve non-uniform channel inputs. Approximate bounds are also derived to evaluate the decoding error probability of the probabilistically shaped MLC-PCM.

Memory Enabled Bumblebee-Based Dynamic Spectrum Access for Platooning Environments

In this paper, we propose a novel memory-enabled non-uniform sampling-based bumblebee foraging algorithm (MEB) designed for optimal channel selection in a distributed Vehicular Dynamic Spectrum Access (VDSA) framework employed in a platoon operating environment. Given how bumblebee behavioral models are designed to support adaptation in complex and highly time-varying environments, these models can be employed by connected vehicles to enable their operation within a dynamically changing network topology and support their selection of optimal channels possessing low levels of congestion to achieve high throughput. As a result, the proposed VDSA-based optimal channel selection employs fundamental concepts from the bumblebee foraging model. In the proposed approach, the Channel Busy Ratio (CBR) of all channels is computed and stored in memory to be accessed by the MEB algorithm to make the necessary channel switching decisions. Two averaging techniques, Sliding Window Average (SWA) and Exponentially Weighted Moving Average (EWMA), are employed to leverage past samples and are evaluated against the no-memory case. Due to the high variability of the environment (e.g., high velocities, changing density of vehicles on the road), we propose to calculate the CBR by employing non-uniform channel sampling allocations as well as evaluate it using both simplified numerical and realistic Vehicle-to-Vehicle (V2V) computer simulations. The numerical simulation results show that gains in the probability of the best channel selection can be achieved relative to a uniform sampling allocation approach. By utilizing memory, we observe an additional increase in the channel selection performance. Similarly, we see an increase in the probability of successful reception when utilizing the bumblebee algorithm via a system-level simulator.

Magnetohydrodynamic (MHD) peristaltic flow of blood containing cylindrical shaped gold nanoparticles in a non-uniform tube in the presence of Joule dissipation

This research scrutinizes the peristaltic transport of blood-based nanofluid comprising cylindrical-shaped Gold (Au) nanoparticles in a non-uniform tube under the influence of magnetic field. Effects of Joule heating and viscous dissipation are also explored. Governing equations are firstly modelled and then simplified by utilizing long wavelength and small Reynold number assumptions. Exact solutions are computed in terms of modified Bessel’s functions. The effects of concerned physical parameters on the dimensionless velocity, trapping, temperature, magnitude of pressure gradient, heat transfer rate is discussed through graphs and tables. Velocity of the fluid decreases by increasing the magnitude of non-uniform parameter. Heat transfer rate is high in the uniform channel as compared to the tapered channel. Moreover, reduction in temperature and axial pressure gradient is also observed in non-uniform channel in comparison to uniform channel. The computation of exact solutions that can be used to test the accuracy of various numerical schemes applicable to these types of complex flow problems is also a novel aspect of this study. Hopefully, this analysis will be helpful in a variety of biomedical therapies, such as in drug delivery, magnetic resonance imaging and magnetic hyperthermia.

Technical computations for dependent shear rate effect on magnetized peristaltic transport of synovia with two fluid viscosity models: Arthritis treatments

AbstractSynovitis studies are the key to the treatment of most arthritis diseases in a human physique. So this study visualizes the effects of two dependent fluid viscosity models on magnet nano peristaltic transport of synovial fluid in nonuniform channel walls. Two fluid models are constructed, the first model considered that the Shear rate is dependent on fluid concentration (model‐I), and the exponentially dependent viscosity on the fluid concentration is proposed as a second model (model‐II). The fluid models are represented by a highly nonlinear system of partial differential equations. Joule heat, thermal radiation, and Arrhenius energy are studied as external effects. Those models are offered in a gradient mechanism, then simplified using droppings bars and using the fact of long wavelength, and low Reynolds. Pressure gradient and trapped bolus profiles and shear stress distribution as well as fluid temperature, velocity, and concentration performance are scrutinized. Analytical results are obtained in appropriate/chosen boundary conditions depending on the walls of the channel. Attracted/signified results are compared with the nearest trusted results by Khan et al. Solution intervals are sub‐divided and analytically treated at each of them by multi‐stage differential transform algorithms. Outcomes gratify that, joints are provided by more cushion and lubrication at high fluid temperatures. Magnetic effects are advised in rheumatoid arthritis treatments, increasing the synovial fluid temperature and allowing fluid particles to move freely inside joints.

Efficient distributed broadcasting algorithms for cognitive radio networks-enabled smart agriculture

Smart agriculture has a broad prospect with the fast development of information technologies, such as Internet of Things, big data, edge computing and artificial intelligence. As more intelligent devices are deployed for agricultural scenarios, such as quality monitoring and information aggregation, the communication channels among these devices will be crowded and the performance can be greatly affected. Cognitive Radio Networks (CRNs) are promising in promoting better spectrum utilization, where unlicensed users can opportunistically use the vacant spectrum assigned to licensed users. On the basis of CRNs, many agricultural scenarios can be empowered with efficient communication capabilities. However, the broadcasting problem, which handles the information dissemination, has not been thoroughly studied in CRNs. Existing works are either centralized solutions performing broadcast on single/multiple channels, or distributed algorithms without performance guarantee for general networks. In this paper, we propose efficient distributed algorithms with short broadcast delay and high success ratio. The difficulties lie in the non-uniform channel availability, which entails broadcasting on multiple channels even for single-hop neighbors, and the distributed behaviors, where the users are only aware of the local information. Our contributions are threefold. First, we propose an efficient distributed rendezvous algorithm which spurs the neighbors to find the common channels in a short time. Second, we handle the single-hop broadcast by presenting two distributed algorithms and they guarantee a successful broadcast in O(Δ2loglogN) and Δ time slots respectively, where N is the number of channels and Δ is the maximum number of neighbors. Finally, we extend these algorithms to multi-hop broadcast and the broadcast delay is only up to D times the delay of single-hop, where D is the network diameter. We also conduct extensive simulations and the results corroborate our theoretical analyses.

Impact of Variable Liquid Properties on Peristaltic Transport of Non-Newtonian Fluid Through a Complaint Non-Uniform Channel

The present investigation emphasises a new attempt at the peristaltic mechanism of Eyring Powell fluid through a non-uniform channel. The analysis is performed in the presence of wall properties under the influence of variable liquid properties, and the flow problem is mathematically developed. The channel walls are subjected to no-slip conditions with long-wavelength and low Reynolds-number approximations employed in the study. The nonlinear governing equations are normalised using relevant non-dimensional parameters, and the solutions are obtained with the help of a regular perturbation technique. The influence of pertinent physical parameters of interest, such as velocity, temperature, concentration and streamlines, are represented graphically. The investigation reveals that the material parameters and elastic parameters of the Eyring Powell fluid model strongly affect the velocity and temperature profiles and that the opposite behaviour has been observed in the material parameters.

Peristaltic Transport of Bingham Fluid through Nonuniform Channel with Convective Conditions and Lorentz Forces

In this study, the impacts of changing the liquid characteristics of the Bingham fluid are highlighted under MHD peristaltic transport. Conditions for convective and porous boundary conditions are taken into consideration. By using proper similarity transformations, the governing equations become dimensionless. For temperature, velocity, and streamlines, the series solution is found. The MATLAB 2019b programming offers a graphical depiction of relevant metrics on physiological flow parameters. The findings demonstrate that lowering the velocity and temperature profiles occurs when the magnetic parameter is increased. Furthermore, the effect of changing viscosity increases the trapped bolus size by a small amount. Once again, the results of the present investigation have significance for our knowledge of the complex rheological mechanisms governing blood flow via small arteries.

Investigation of Entropy Production with Thermal Analysis under Soret and Dufour Effects in MHD Flow between Convergent and Divergent Channels.

Hydromagnetic flow and heat transport have sustainable importance in conventional system design along with high-performance thermal equipment and geothermal energy structures. The current computational study investigates the energy transport and entropy production due to the pressure-driven flow of non-Newtonian fluid filled inside the wedge-shaped channel. The nonlinear radiation flux and uniform magnetic field are incorporated into the flow analysis. To be more precise, non-Newtonian fluid initiates from an inlet with the bound of the parabolic profile and leaves at outlet of a convergent/divergent channel. We assume that the channel flow is adiabatic and influenced by the wall friction. The leading flow equations are modeled via the Carreau fluid model using fundamental conservation laws. The thermodynamical aspect of the system is visualized using a two-phase model and analyses of the entropy equation due to fluid friction, ohmic heating, and diffusion of heat and mass fluxes. The modeled system of equations is normalized using a dimensionless variable mechanism. The system was elevated for the significant variation of controlling parameters. The outcomes obtained from the computational investigation are validated with the theoretical results that are available in the literature. An increasing semivertex angle and Reynolds number increase the converging channel flow. In the core flow zone, an increase in the divergent semiangle causes the flow to decelerate, while near and at the channel wall it causes a slight acceleration. Outcomes designate that the main contribution to the irreversibility is due to ohmic loss, frictional loss, and heat loss. The thermal performance and entropy production is dominant for a diverging flow. The outcomes of this research will assist in comprehending the process of entropy minimization in conjunction with the flow of nanomaterials in a nonuniform channel, which is essential in engineering processes such as the creation of micro machines, supersonic Jets, nozzles, and clean energy.

Stamping of Nonuniform Channels. 7. Kinematic and Stress State of the Workpiece in Constrained Extrusion. 7.1. Plastic Region under Thick Wall

Stamping of Nonuniform Channels. 7. Kinematic and Stress State of the Workpiece in Constrained Extrusion. 7.1. Plastic Region under Thick Wall

Peristaltic Transport of a Couple Stress Fluid through a Horizontal Tapered Asymmetric Channel

Abstract: The peristaltic transport of a Couple stress fluid in the horizontal tapered asymmetric channel is examined, concealed by long wavelength and low Reynolds number assumptions. The tapered asymmetric channel is produced due to the peristaltic motion on the walls of the non-uniform channel having alternative amplitudes and phases. Excellent velocity, pressure gradient, and stream function results have been determined. Numerical evaluation has also been found for investigating the pumping characteristics with various flow values of parameters. It has been shown that the peristaltic transport pumping decreases with an increase in non-uniform rheological parameters. Further, our conclusion is created to be very relevant to [19] when the absence of the tapered asymmetric nature of the channel and couple stress fluid parameter.

Mathematical modeling and simulation of peristaltic activity in Ree-Eyring fluid flow through non-uniform complaint channel: Different varying conditions

The current study incorporates variable viscosity and thermal conductivity on modeling Ree-Eyring fluid flow inside a peristaltic non-uniform complaint channel. The small Reynolds number and long-wavelength approximations are employed for resolve the governing nonlinear differential equations. Temperature expression is obtained with the help of series solution method. The graphs are drawn on relevant parameters to investigate its effect on velocity, temperature, concentration, and streamlines through MATLAB 2020b. The results confer more velocity in the Newtonian fluid in comparison with non-Newtonian fluid. Also, the model discloses that the size of the bolus can be varied by varying the viscosity parameter. This result helps in understanding the thrombus formation in blood vessels.

Entropy Generation for MHD Peristaltic Transport of Non-Newtonian Fluid in a Horizontal Symmetric Divergent Channel

The analysis in view is proposed to investigate the impacts of entropy in the peristaltically flown Ree–Eyring fluid under the stress of a normally imposed uniform magnetic field in a non-uniform symmetric channel of varying thickness. The administering equations of the present flow problem are switched into the non-dimensional form and then reduced by the availing of long wavelengths and creeping flow regime restrictions. The analytical treatment for the developed problem is performed to attain closed-form solutions which are further displayed as graphs of velocity, pressure, temperature, and entropy distribution. The trapping phenomenon has also been an area of our current examination. The role of relevant pronounced parameters such as the Brinkmann number, Hartmann number, and Ree–Eyring parameter for throwing vivid impacts are also concerned. It has been inferred that both the Brinkmann number and Ree–Eyring parameter with rising values inflate temperature and entropy profiles. The velocity profile shows the symmetric nature due to the horizontally assumed symmetric channel of varying thickness. The circulation of streamlines and bolus formations is visibly reduced in response to the increasing Hartmann number.

Mathematical simulation of double diffusion convection on peristaltic pumping of Ellis nanofluid due to induced magnetic field in a non-uniform channel: Applications of magnetic nanoparticles in biomedical engineering

The present research explores the wave of peristalsis on magneto Ellis nanofluids within non-uniform channel by using Dufour and Soret parameters. The mathematical representation of the magneto Ellis nanofluids having double diffusion convection under magnetic flux is presented in detail. The nonlinear partial differential equations are simplified by applying long wavelength and lesser Reynolds number. The resultant differential equations are further simplified numerically, and exact solutions of concentration, temperature, and nanoparticle fraction are computed. Further, the significance of numerous material constraints of flow quantities is depicted through graphs. It is revealed that the huge value of Brownian motion and Soret number decreases the concentration of nanosolid particle. Solid nanoparticles in a nanofluid during micro-mixing procedure collide randomly hence transferring the molecular energy into thermal energy that triggers the rise in temperature.

Granular flows in drums of non-uniform widths

We study how channel width variations influence the dynamics of free-surface granular flows. For this purpose, we extend a continuum model framework to granular flows passing through channels that narrow or widen. Our theory uses a linearized approximation to an established dense granular flow rheology and a Coulomb friction law to model interaction between flow and sidewalls. We test the theoretical predictions using two novel 40 cm-diameter drums (convex and concave) filled halfway with 2 mm diameter particles rotated at rates in which the shear layer remains shallow and dense. We apply particle tracking velocimetry to enable quantitative comparisons between experimental data and theoretical predictions. We find that our experimental kinematics and energy profiles largely agree with the theoretical predictions. In general, flows through narrowing channels are faster and deeper than flows through widening channels. The influence of width variations grows with increasing flow speed, and the form of the rate dependence changes fundamentally as the regime changes from one in which kinetic energy is dissipated locally to one in which it is advected downstream. For both regimes, theoretical scaling analysis leads us to experimentally validated power laws, in which the exponent depends on the flow regime, and the multiplicative coefficient depends on channel geometry alone. Finally, we discuss how the differences between theoretical predictions and experimental data may be useful for improving our understanding of flows through non-uniform channels.

UNDERWATER CHANNEL RECOVERY SCHEME IN DELAY-DOPPLER DOMAIN USING MODIFIED BASIC PURSUIT DENOISING WITH PRIOR KNOWLEDGE

The signal denoising problem is a major challenge in underwater communication (UWC). The denoising problem in UWC has been addressed, where channel estimation approaches are provided in terms of sparsity, time, and frequency. Convex optimization is currently widely used for recovering sparse signals from compressed data. A nonuniform sparse 2D frequency-domain channel recovery scheme in the delay-Doppler domain representation is provided as a mathematical framework to solve channel estimation problems. Compressive sensing (CS) at higher Doppler frequencies (high channel mobility) and near full-rate sampling at lower Doppler frequencies (stagnant channel) are used to recover both rapid-fluctuating as well as slow-varying channel components with high precision. The prior knowledge of modified basic-pursuit denoising channel estimation based on nonuniform CS and sparsity-constrained least-squares has been discovered, where <i>l</i><sub>1</sub>-minimization of element wise multiplication of the equal-size vectors is performed. The proposed channel estimation scheme is compared with conventional CS over a sampling ratio, ambient noise level, and observation window length. The acoustic channel simulations and experimental channel data from SPACE08 are used to verify prior knowledge provided by the proposed scheme. Simulation results confirm the superiority of the proposed algorithm for channel estimation over the existing ones.

Heat transfer in a non-uniform channel on MHD peristaltic flow of a fractional Jeffrey model via porous medium

Heat transfer in a non-uniform channel on MHD peristaltic flow of a fractional Jeffrey model via porous medium

Topology design of cold plates for pouch battery thermal management considering heat distribution characteristics

The topology optimization technique was applied to the structural design of the cold plate for pouch Lithium-ion batteries in this study, aiming to boost its overall performance. With maximum heat transfer and minimum flow resistance as the optimization objectives of the cold plate channel, we proposed a topology approach for non-uniform heat generation, motivated by the inhomogeneous cell heat distribution. The optimization iteration yielded a non-uniform channel structure (N-type) with a denser channel distribution in the hot zone. According to the topology results, a simplified cooling system model for the 50 V battery module was constructed and investigated numerically. Under constant and dynamic current conditions, the N-type cold plate was compared to cold plates with other two channel structures: the uniform channel type and the straight channel type. As a result, the N-type cold plate showed the best comprehensive performance. Furthermore, the optimal design of the cooling system with different inlet and outlet layouts, channel depths and inlet mass flow rates was explored. The N-type cold plate with bottom inlet-top outlet layout, channel depth of 2.5 mm, inlet width of 15 mm and mass flow rate of 8 g s-1 is the ideal choice for the cooling system at 2C discharge. The j/f factor reached the maximum value of 3.42, with the pump power consumption and the Nusselt number being 2.53×10-3W and 39.26, respectively. The topology cold plate and optimization method proposed in this study can be used to increase the performance of BTMS.

Multiple aspects of heat generation/absorption on the hydromagnetic flow of Carreau nanofluids via nonuniform channels

The use of nanofluid technology as a working fluid in specific channels has significantly improved heat exchange rate in thermal engineering applications. In fact, nonuniform channels with converging or diverging nature offer special characteristics that encourage the most favorable usage, such as flow via nozzles, diffusers, and reducers in polymer processing and flow through canals and rivers. Therefore, we present a theoretical and mathematical insight into nanofluid heat transfer and flow dynamics in nonuniform channels utilizing non-Newtonian nanofluids. The impacts of heat absorption/generation and Joule heating in a magnetohydrodynamics (MHD) flow of Carreau nanofluids with viscous dissipation are addressed in this research. Brownian and thermophoresis diffusion are deliberated to investigate heat and mass transport mechanisms. The modeled flow equations are numerically handled using a built-in MATLAB code based on the finite difference approach (bvp4c) for velocity, temperature, and concentration fields. The consequences of the variable magnetic field, heat absorption/generation, and numerous physical parameters on the temperature and concentration field are surveyed. The results indicate that the increasing values of heat generation/absorption parameter and Eckert number significantly enhances the temperature profiles in convergent channel. In addition, a similar behavior is observed for higher Prandtl number. An assessment of solutions achieved in this article is made with existing data in the literature.

Experimental and theoretical study on the onset of nucleate boiling in non-uniform heating tube bundle channel

The transverse non-uniform heating tube bundle exists in steam generator and will affect the heat transfer and flow conditions in the shell side. It is important for the operational performance of the steam generator. In this study, a non-uniform heating tube bundle channel experimental device was set up. The channel consisted of two groups of heating tube bundles which were non-uniform heating in the transverse direction and uniform heating in the axial direction. Experiments and theoretical analysis were conducted to evaluate the influence of transverse non-uniform heating on the Onset of Nucleate Boiling (ONB). The locations of ONB during the experiments were determined from the heat transfer coefficient variations and the tube wall temperature variations. Experimental results at ONB were compared with existing well-known correlations under uniform heating conditions. And then under non-uniform heating conditions, the experimental wall superheat at ONB were furthermore compared with results predicted by the verified existing correlation. It was found that the correlation can’t predict the experimental wall superheats well under transverse non-uniform heating conditions. Therefore, the influence of transverse non-uniform heating on ONB was theoretically analyzed. Correction factors were theoretically introduced and a new correlation was proposed. This new correlation was examined with experimental data and the result showed the correction factors need to be further studied.