Cylindrical Region Research Articles

Improving Thermal Friction Drilling Performance of AISI 304 Stainless Steel Using the Harris Hawk Optimization Method

Presently, in friction drilling optimization schemes, quick convergence of solutions and simplicity of methods are still challenging. These issues are drawbacks in obtaining the maximum potential benefits from the optimization process. Therefore, this paper applies a new optimization method, Harris Hawk optimization to the thermal drilling process of AISI 304 stainless steel. The algorithm minimizes the axial force, determination error, radial force, and radial error and maximizes the bushing length as the major output of the process. The proposed approach was tested with experimental data obtained from the literature. The obtained results indicate that the optimal production is feasible. An example is given here of the results of the input parameters for the minimum axial force, which is as follows: After 500 iterations, the optimal axial force yields a tool cylindrical region diameter of 5.78593 mm, a friction angle of 60 degrees, a friction contact area ratio of 57.7082, workpiece thickness of 3 mm, feed rate of 140 mm/min and rotational speed of 3002.85 rpm, which can be applied. The results assist engineers in implementing optimal conditions for the drilling process. The outcome of this study strengthens decisions to establish thresholds of values that are less or more than expected thereby providing a basis for comparison, reward, and reprimand for workers. Thus the drilling process can be optimized.

Local boundedness and Harnack inequality for an inverse variational inequality problem with double nonlinear parabolic operator in finance

The objective of this paper is to investigate a class of initial boundary value problems for inverse variational inequalities that arise from financial matters. By utilizing the energy inequality on a localized cylindrical region and the Caffarelli–Kohn–Nirenberge inequality, we establish the local boundedness and the Harnack inequality of weak solutions to the variational inequality.

Molecular Dynamics Simulation of High-Energy Beam Irradiation of SiO2 Single Crystal with Three Different Morphologies: No Free Surface, with a Free Surface, and Thin Films

High-energy beam irradiation of SiO2 crystal with the α-quartz structure was simulated by the molecular dynamics method. Three types of specimen structures were examined: a single crystal without a free surface, a single crystal with a free surface, and a thin film. After structural relaxation at room temperature, a cylindrical region with diameter of 3.0 nm was set at the center of the specimen and high-thermal energy of S eff = 0.1–4.0 keV nm−1 was added to that region, where S eff is the effective stopping power. Atomic motions were calculated by the molecular dynamics method using the large-scale atomic/molecular massively parallel simulator. Vashishta potential was used for the atomic interaction. The single crystal structure of α-quartz without the free surface was stable up to 1.0 keV nm−1 and it gradually became amorphous with increasing thermal energy. In contrast, the single crystal structure with the free surface was stable up to 0.5 keV nm−1 and was amorphous at higher thermal energy. In particular, the atomic structures for the thermal impact S eff ≥ 2.0 keV nm−1 had a facet-like structure at the impacted surface, which corresponds to actual experimental results. Nano-hole formation was observed in the irradiation process of the film structure.

ANALYSIS OF THE THERMAL FRICTION DRILLING PROCESS FOR EFFECTIVE PARAMETRIC CHOICE ON THE DRILLING OF AISI 304 STAINLESS STEEL USING THE FUZZY AHP-MOORA METHOD

Attaining effective quality control of drilled samples in thermal friction drilling is a challenge considering the disproportionate allocation of drilling resources to parameters. Therefore, it is essential to select the appropriate parameters and allocate their scarce resources based on requirements. This paper chooses the effective and the best parameters of the drilling process during the processing of AISI 304 stainless steel using the fuzzy-AHP-MOORA method. The analytic hierarchy process is deployed by stating the criteria and alternatives. A pairwise comparison is made with the outcome introduced into a fuzzy framework which interpretes the obtained values from an input to an output vector via a rule (linguistic the terms) set. The result is expressed as responses to options compared to the objectives as ratios. The input parameters are the feed rate, friction angle, rotational speed, friction contact area proportion, tool cylindrical region diameter and workpiece thickness. In turn, the responses are the roundness error, radial force, dimensional error, axial force, bushing length and hole diameter. It was found that experimental trials 12, 14 and 8 with the respective differences between beneficial and non-beneficial values of 0.2133, 0.2076 and 0.1083 obtained the respective positions of 1st, 2nd and 3rd. The discretized fuzzy weights place the bushing length as the best while the second position is shared equally by all the other responses. The model was successful in reducing the imprecision in the parameters and the greatly improved response was the bushing length.

Impact of annular nanosecond plasma actuators on drag reduction in transonic flow

During the last few decades, plasma actuators have emerged as promising devices for aerodynamic flow control. This study focuses on the use of nanosecond plasma actuators for such purposes. A thermal phenomenological model is employed to simulate the effects of these actuators. The propagation of shock waves and their interactions for two specific geometries of plasma actuators, linear and annular plasma synthetic jet actuators, are examined here. A comparative analysis of the performance of these two configurations is presented. Furthermore, the geometric characteristics and temperature model are analyzed to provide insights that can be applied to practical problems. The influence of the actuators on a projectile in the transonic flow is also investigated. The results of the present study show that actuators placed in the conical and cylindrical regions of the object do not contribute to drag reduction. Conversely, actuators positioned at the boat-tail and base of the object effectively reduce drag. This drag reduction is primarily attributed to thermal disturbances in the separation area. Additionally, it is observed that the effects of shock waves and their interaction with stationary waves around the projectile are negligible in terms of drag force reduction.

Simplified Polynomial-asymptotic-distribution Actuator Disc (SPAD) method for wind turbine wake simulation based on k-[formula omitted]-[formula omitted] turbulence model

In large wind farms, wake effect has a negative impact on the annual production of wind turbines. As a result, wind turbine wake simulation is important for wind farm micro-sitting to minimize power loss and maximize energy production. Coupled with Reynolds Averaged Navier–Stokes turbulence model, Simplified Uniform-distribution Actuator Disc method is the most widely-used rotor model for wake simulation in engineering practice. The conventional simplified uniform-distribution actuator disc models suffer discrepancies of wake velocity prediction compared with the measurements in the near wake region. The novelty of the current research is to propose a Simplified Polynomial-asymptotic-distribution Actuator Disc method based on k−ϵ−fP turbulence model for cylindrical actuator disc cell region with finite thickness, which is simple for implementation and improves the accuracy of wake simulation compared with conventional method. The proposed method conforms to momentum conservation and is as simple as conventional method because of its polynomial formulation and no requirement for aerodynamics data in Generalized Actuator Disc model. From the verification and validation cases, it can be found that the proposed model has better agreement with both high-fidelity actuator line model and the field test measurements from Lillgrund wind farm compared with conventional model. The proposed actuator disc model has the potential to be applied to the micrositting of large offshore wind farms in the future.

Experimental and numerical investigations of heat transfer characteristics of a piston cooling bore impinged by SAE 30 oil

The jet impingement technique is currently one of the most efficient cooling solutions for highly reinforced pistons of large two-stroke engines. To study the heat transfer characteristics of piston, experimental and numerical investigations with a piston cooling bore impinged by SAE 30 oil were carried out. To investigate the heat transfer coefficient distributions over the target bore, the wall temperatures of the cooling bore were measured by thermocouples, which will also be used in the numerical calculation. The jet Reynolds number (Re) ranges from 220 to 330, and the jet-to-plate spacing ratios (H/D) range from 10 to 30. Results show that jet-to-plate spacing ratios have a slight effect on the heat transfer coefficient for this low Reynolds numbers impingement which is quite different from high Reynolds numbers flow. There are both three peaks of the local heat transfer coefficient for Re = 330 and 280 along the x-axis direction. However, only two peaks occur when Re = 280. The heat transfer coefficient increases with the increase of Reynolds number when x/D < 0.22 or x/D > 1.77 while the variation is contrary when 0.22 < x/D < 1.77. The average heat transfer coefficient of the top surface region is far larger than other regions and decreases significantly in the upper chamfered region. While it is almost identical in the cylindrical region for different Reynolds numbers. This study provides the heat transfer characteristics of piston cooling with SAE30 oil and can be used for the piston optimization of large two-stroke engines with high cooling performance requirements.

Mathematical Modeling of the Heat Transfer Process in Spherical Objects with Flat, Cylindrical and Spherical Defects

This paper proposes a method for determining the optimal parameters for the thermal testing of plant tissues of fruits and vegetables containing surface and subsurface defects in the form of areas of plant tissues with different thermophysical characteristics. Based on well-known mathematical models for objects of predominantly flat, cylindrical and spherical shapes containing flat, spherical and cylindrical regions of defects, numerical solutions of three-dimensional, non-stationary temperature fields were found, making it possible to measure the power and time of the thermal exposure of the sample surface to the radiation from infrared lamps using the finite element method. This made it possible to ensure the reliable detection of a temperature contrast of up to 4 °C between the defect and defect-free regions of the test object using modern thermal imaging cameras. In this case, subsurface defects can be detected at a depth of up to 3 mm from the surface. To determine the parameters of mathematical models of temperature fields, such as thermal conductivity and a coefficient of the thermal diffusivity of plant tissues, a new method of a pulsed heat flux from a flat heater is proposed; this differs in the method of processing experimental data and makes it possible to determine the required characteristics with high accuracy during the active stage of the experiment in a period not exceeding 1–3 min.

Weld Defect Inspection of Cylindrical Secondary Batteries Based on Active Thermographic Measurement with Thermal Magnification

This paper presents an active thermographic measurement-based inspection tech-nique for detecting weld defects in the battery cap region of cylindrical secondary batteries. As the proliferation of electric vehicles continues, safety issues related to secondary batteries have become prominent. In this study, a defect detection algorithm was developed by aligning visual images and active thermographic im-ages of the cylindrical secondary battery cap region. Lock-in amplitude images during the heating-cooling process using a laser were extracted to measure the difference in temperature patterns arising from internal structural variations. Ad-ditionally, to minimize the influence of surface conditions and temperature varia-tions other than laser-induced, a 10Hz periodic heating was employed, and ther-mal magnification in the heating frequency was achieved through data processing. This approach allowed the measurement of temperature changes induced by laser heating and cooling while minimizing the impact of surface conditions and tem-perature variations unrelated to the laser. A dataset of 1000 specimens was con-structed by aligning thermographic data with vision images acquired through this method. defective samples. Using this thermographic-vision alignment dataset, a defect detection algorithm was trained to achieve a more accurate and faster in-spection performance compared to existing non-destructive testing technologies.

Vorticity suppression by multiphase effects in shock-driven variable density mixing

Shock-driven variable density mixing has been frequently explored through the single-phase Richtmyer–Meshkov instability. Here, such mixing is considered when driven by a multiphase component, the Shock-Driven Multiphase Instability (SDMI). The simple case of a solid particle seeded gas in a cylindrical region surrounded by clean gas is studied. It has been previously shown that the particle-phase can lag behind the gas, diminishing vorticity deposition. In this letter we present theoretical analysis of the vorticity deposition, and a new model predicting the circulation deposition for an SDMI as a function of particle relaxation distance and hydrodynamic mixing strength. The theory is founded on a simplified vorticity equation, advection and multiphase source terms, using simple drag models to predict the particle dynamics, and scaling the results using existing circulation models for the Richtmyer–Meshkov instability in the small particle limit. The model is compared to new high-fidelity experimental data, and previous experiments and simulations, finding good agreement. This model provides the first theoretical prediction of mixing suppression in the SDMI.

Electrokinetic energy conversion and desalination of an asymmetric nanopore with applied temperature gradients

The electrokinetic energy conversion (EKEC) and desalination performance of a cation-selective funnel-shaped nanopore are investigated theoretically through a continuum description. The effects of pore geometry, characterized by a symmetric factor between the conical and the cylindrical regions, are considered along with pressure and temperature gradients. A desalination index is proposed to evaluate the performance of desalination, examining the trade-off between the ion rejection rate and the volumetric flow rate. It is found that applying a positive (or negative) ∆T relative to ∆P lowers (or raises) the rejection rate, as influenced by the ion selectivity. In addition, the rejection rate at a positive pressure difference (∆P>0; flow coming from tip to base) is slightly larger than that at ∆P<0 because the former has a stronger inlet electric field. Based on the desalination index, a positive ∆T manifests a better desalination performance than a negative ∆T, in contrast to the EKEC case, which displays better energy efficiency under a negative ∆T than under a positive ∆T. The smaller diffusivity of Na+ compared with K+ makes the power density and efficiency of NaCl better than those of KCl. Meanwhile, the more significant thermal diffusion for NaCl impacts its rejection rate more appreciably.

Electron distribution near the fast ion track in silicon

A model is proposed to describe the distribution of electrons near the track of a fast ion. The dependence of the fast electron flux on time, layer depth, and radial variable is modeled taking into account the statistical weight of each trajectory. It has been found that the pulse duration in the electron flux distribution is fractions of picoseconds, and the radial size of the cylindrical region where fast electrons are transported reaches tens of angstroms.

Exploration of underlap induced high-k spacer with gate stack on strain channel cylindrical nanowire FET for enriched performance

This research explores a comprehensive examination of gate underlap incorporated strained channel Cylindrical Gate All Around Nanowire FET having enriched performances above the requirement of the 2 nm technology node of IRDS 2025. The device installs a combination of strain engineering based quantum well barrier system in the channel region with high-k spacers sandwiching the device underlaps and stack high-k gate-oxide. The underlaps are prone to parasitic resistance and various short channel effects (SCEs) hence, are sandwiched by HfO2 based high-k. This SCE degradations and a strong electric field in the drain-channel region is rendered controlling the leakages. The strain based Nanosystem engineering is incorporated with Type-II heterostructure band alignment inducing quantum well barrier mechanism in the ultra-thin cylindrical channel region creating an electrostatic charge centroid leading to energy band bending and splitting among the two-fold and four-fold valleys of the strained Silicon layer. This provides stupendous electron mobility instigating high current density and electron velocity in the channel. Thereby, the device is susceptible to on-current enhancement via ballistic transport of carriers and carrier confinement via succumbing of quantum charge carriers. The device transconductance, Ion, Ioff, Ion/Ioff ratio are measured and the output performance (ID-VDS) characteristics is determined providing emphatic enrichments in contrast to the existing gate all-around FETs as well as the 2 nm technology node data of IRDS 2025. Hence, the strained channel Nanowire FET device developed here is presented here as the device of the future for various digital applications, RF applications and faster switching speed.

Cylindrical orthogonal norm-based stochastic collision risk measures in spacecraft formation flying

The cylindrical orthogonal collision region (COCR) is introduced for the approximate satisfaction of spherical, three-dimensional avoidance constraints (S3ACs) used in spacecraft formation flying (SFF). The COCR construct affords safety sufficiency and reduced constraint satisfaction conservatism over other commonly employed regions, while it may allow for improved efficiency of collision-safe trajectory computation. The COCR is deterministically well-defined; instantaneous and joint-time stochastic measures of collision risk based on the COCR are well-defined and computable; probabilistic collision risk conservatism introduced by the COCR is characterized as consistent with volumetric conservatism. These results, which are validated computationally in pertinent relative orbital cases, demonstrate the feasibility of SFF collision risk management applications which perform COCR-based S3AC satisfaction.

Spatial Behavior of Solutions in Linear Thermoelasticity with Voids and Three Delay Times

This brief contribution aims to complement a study of well-posedness started by the same authors in 2020, showing—for that same mathematical model—the existence of a domain of influence of external data. The object of investigation, we recall, is a linear thermoelastic model with a porous matrix modeled on the basis of the Cowin–Nunziato theory, and for which the heat exchange phenomena are intended to obey a time-differential heat transfer law with three delay times. We therefore consider, without reporting it explicitly, the (suitably adapted) initial-boundary value problem formulated at that time, as well as some analytical techniques employed to handle it in order to address the uniqueness and continuous dependence questions. Here, a domain of influence theorem is proven, showing the spatial behavior of the solution in a cylindrical domain, by activating the hypotheses that make the model thermodynamically consistent. The theorem, in detail, demonstrates that for a finite time t&gt;0, the assigned external (thermomechanical) actions generate no disturbance outside a bounded domain contained within the cylindrical region of interest. The length of the work is deliberately kept to a minimum, having opted where possible for bibliographic citations in favor of greater reading fluency.

A Legendre spectral‐Galerkin method for fourth‐order problems in cylindrical regions

AbstractA spectral‐Galerkin method based on Legendre‐Fourier approximation for fourth‐order problems in cylindrical regions is studied in this paper. By the cylindrical coordinate transformation, a three‐dimensional fourth‐order problem in a cylindrical region is transformed into a sequence of decoupled fourth‐order problems with two dimensions and the corresponding pole conditions are also derived. With appropriately constructed weighted Sobolev space, a weak form is established. Based on this weak form, a spectral‐Galerkin discretization scheme is proposed and its error is rigorously analyzed by defining a new class of projection operators. Then, a set of efficient basis functions are used to write the discrete scheme as the linear systems with a sparse matrix based on tensor product. Numerical examples are presented to show the efficiency and high‐accuracy of the developed method. Finally, an application of the proposed method to the fourth‐order Steklov problem and the corresponding numerical experiments once again confirm the efficiency and spectral accuracy of the method.

Complex analytic dependence on the dielectric permittivity in ENZ materials: The photonic doping example

AbstractMotivated by the physics literature on “photonic doping” of scatterers made from “epsilon‐near‐zero” (ENZ) materials, we consider how the scattering of time‐harmonic TM electromagnetic waves by a cylindrical ENZ region is affected by the presence of a “dopant” in which the dielectric permittivity is not near zero. Mathematically, this reduces to analysis of a 2D Helmholtz equation with a piecewise‐constant, complex valued coefficient a that is nearly infinite (say with ) in . We show (under suitable hypotheses) that the solution u depends analytically on δ near 0, and we give a simple PDE characterization of the terms in its Taylor expansion. For the application to photonic doping, it is the leading‐order corrections in δ that are most interesting: they explain why photonic doping is only mildly affected by the presence of losses, and why it is seen even at frequencies where the dielectric permittivity is merely small. Equally important: our results include a PDE characterization of the leading‐order electric field in the ENZ region as , whereas the existing literature on photonic doping provides only the leading‐order magnetic field.

Interpreting Sunyaev–Zel’dovich observations with MillenniumTNG: mass and environment scaling relations

ABSTRACT Sunyaev–Zel’dovich (SZ) measurements can dramatically improve our understanding of the intergalactic medium and the role of feedback processes in galaxy formation, allowing us to calibrate important astrophysical systematics in cosmological constraints from weak lensing galaxy clustering surveys. However, the signal is only measured in a two-dimensional projection, and its correct interpretation relies on understanding the connection between observable quantities and the underlying intrinsic properties of the gas, in addition to the relation between the gas and the underlying matter distribution. One way to address these challenges is through the use of hydrodynamical simulations such as the high-resolution, large-volume MillenniumTNG suite. We find that measurements of the optical depth, τ, and the Compton-y parameter, Y, receive large line-of-sight contributions that can be removed effectively by applying a compensated aperture photometry filter. In contrast with other τ probes (e.g. X-rays and fast radio bursts), the kinematic SZ-inferred τ receives most of its signal from a confined cylindrical region around the halo due to the velocity decorrelation along the line of sight. Additionally, we perform fits to the Y–M and τ–M scaling relations and report best-fitting parameters adopting the smoothly broken power law formalism. We note that subgrid physics modelling can broaden the error bar on these by 30 per cent for intermediate-mass haloes (${\sim }10^{13} \, {\rm M}_{\odot }$). The scatter of the scaling relations can be captured by an intrinsic dependence on concentration and an extrinsic dependence on tidal shear. Finally, we comment on the effect of using galaxies rather than haloes in observations, which can bias the inferred profiles by ∼20 per cent for L* galaxies.

On Performance Analysis for Random 3D Mobile AUV Networks With Limited Data Buffers

In this paper, we consider a finite network of multiple mobile autonomous underwater vehicles (AUVs) collectingdata in a given region and transferring them to a surface sink. All AUVs patrol a cylindrical region and dynamically control their 3-Dimensional (3D) location according to the random way-point (RWP) mobility model. Our specific interest focuses on the system throughput under different locations of the serving AUV. The following three serving AUV selection policies are investigated: 1)The serving AUV is the closest AUV among all active AUVs; 2) The serving AUV is randomly selected among the active AUVs; 3)The serving AUV is the farthest AUV among all active AUVs. Under the time slotted network scenario, the system throughput is defined as the probability that the sink can successfully recover the data packet from the serving AUV in one time slot. Further, we consider a practical constraint that all AUVs are equipped with limited data buffers. Based on the probability distributions of the distances between the AUVs and the surface sink, this paper presents a mathematical framework to characterize the performance of the random 3D mobile network. With the help of this framework, we obtain the theoretical performance in terms of the system throughput of the surface sink and the average queue delay of any AUV. Finally, extensive simulations are presented to verify the accuracy of our analysis and study the effects of various parameters.

Classification of Rank-One Submanifolds

We study ruled submanifolds of Euclidean space. First, to each (parametrized) ruled submanifold sigma , we associate an integer-valued function, called degree, measuring the extent to which sigma fails to be cylindrical. In particular, we show that if the degree is constant and equal to d, then the singularities of sigma can only occur along an (m-d)-dimensional “striction” submanifold. This result allows us to extend the standard classification of developable surfaces in {mathbb {R}}^{3} to the whole family of flat and ruled submanifolds without planar points, also known as rank-one: an open and dense subset of every rank-one submanifold is the union of cylindrical, conical, and tangent regions.