Mechanical Phenomena Research Articles

Characterization and optimization of continuous ohmic thermal sterilization based on the development of a predictive computational toolbox

Continuous thermal processing (CTP) is a common method for sterilizing food. However, it can result in an uneven temperature distribution, which can lead to a varying degree of processing intensity. Ohmic heating (OH) can be advantageous in this regard, as it enables volumetric heating for more homogenous treatments. However, evaluating the processing intensity distribution inside the equipment for OH is challenging due to the complex interaction between electrical, mechanical and thermal phenomena. Furthermore, the comparison of OH and conventional heating treatments often lack a profound basis of comparable treatment intensity considerations. To gain a deeper mechanistic understanding of the technology, a numerical computational fluid dynamics model for the OH sterilization of a clear carrot juice from the heating region to the cooling process was developed. The model was validated with thermal and electrical measurements and showed an error rate below 2.5% in its prediction capacities. Moreover, the model was implanted for the validation of the products sterilization and compared to a conventional validation approach, reviling a 33.3% underestimation of the thermal load by conventional manners, which can lead to faulty sterilization of the food product. Additionally, the model was expanded to also be able to predict the microbial inactivation ratio of the system with an average error of 1.10±0.74%. In addition, results indicate that the numerical calculation of the F0 values and their validation with the microbial inactivation ratio have a notable potential for localization and evaluation of hotspots in OH simulations. Therefore, it can be seen as a promising step for establishing a foundation for computer-assisted optimization of CTP and targeted processing.

Construction of the New Wave Solutions of Modified Camassa-Holm and Degasperis-Procesi Equations with Atangana’s Conformable Derivative

In this study it is aimed to expose the new exact wave solutions of time-fractional modified Camassa-Holm (mCH) and time-fractional modified Degasperis-Procesi (mDP) equations due to being extensively used to delineate many physical phenomena in fluid mechanics, hydrodynamics and optical fibers. The aforementioned fractional equations are transformed into nonlinear ordinary differential equations (NLODE) considering the Atangana’s conformable derivative (ACD). Then the (m+1/G’)-expansion method is applied for these NLODEs to obtain the desired exact solutions of the fractional evolution equations. The evaluations are fulfilled through the software system Mathematica. Also the reported solutions in this manuscript are compared with the ones in the literature for the time-fractional CH and DP equations and the behaviors of the solutions are presented graphically.

Analysing All-Optical Random Bit Sequences Using Gap-Based Approaches.

Quantum mechanical phenomena are revolutionizing classical engineering fields such as signal processing or cryptography. When randomness plays an important role, like in cryptography where random bit sequences guarantee certain levels of security, quantum mechanical phenomena allow new ways of generating random bit sequences. Such sequences have a lot of applications in the communication sector, e.g., regarding data transmission, simulation, sensors or radars, and beyond. They can be generated deterministically (e.g., by using polynomials, resulting in pseudo-random sequences) or in a non-deterministic way (e.g., by using physical noise sources like external devices or sensors, resulting in random sequences). Important characteristics of such binary sequences can be modelled by gap processes in conjunction with the probability theory. Recently, all-optical approaches have attracted a lot of research interest. In this work, an adaptation of the quantum key distribution setup is utilized for generating randomised bit sequences. The simulation results show that all-optically generated sequences very well resemble the theoretically ideal probability density characteristic. Additionally, an experimental optical setup is developed that confirms the simulation results. Furthermore, m-sequences show very promising results as well as Gold sequences. Additionally, the level of burstiness, i.e., the distribution of ones and zeros throughout the sequence, is studied for the different sequences. The results enable the finding that generator polynomials with concentrated non-zero coefficients lead to more bursty bit sequences.

Implementation of three-dimensional contact algorithm in numerical manifold method for the structural impact simulation

Structural impact often accompanies large amounts of contacts and leads to complex mechanical phenomena. In solid mechanics, the numerical manifold method (NMM) is proposed to address problems featuring continuous-discontinuous transitions by utilizing a dual coverage system encompassing both mathematical and physical covers. In the present work, a penalty contact algorithm for 3DNMM based on cover-based contact theory is programmed and applied to impact mechanics problems. The accuracy of the developed contact algorithm is firstly calibrated through free-falling blocks and collision blocks. The influence of contact parameters on contact convergence is systematically studied, and three preliminary criteria for how to set contact parameters are provided. The effectiveness of the contact algorithm is verified by conserving system momentum during block collisions. Subsequently, the contact algorithm is applied to Taylor rod and car-streetlight impact simulation, further confirming its effectiveness in modeling high-speed collisions, large displacements, and large deformations of structures. By comparing the 3DNMM results with those from Abaqus, the contact algorithm developed here performs exceptionally well in solving collision problems and produces results consistent with commercial software. The research results in the present work verify the applicability and accuracy of the proposed contact algorithm in solving structural dynamic impact problems. The present work also provides guidance for contact parameter setting in impact problems.

Influence of Nonstationary Processes in Drill Rigs on the Durability of Structural Elements

Assessing the effects that nonstationary dynamic processes have on the durability of structural elements belongs to an important trend in modern dynamics and technical diagnostics of machines. Normally, fatigue strength calculations are performed taking into account only periodically variable stresses, as steady operating modes of machines are much longer in comparison with transient modes. However, a significant role in fatigue failure in machines and engineering structures is also played by nonstationary loads. This is explained by emerging intensive oscillations in the mechanical system during accelerating, braking, or changing the operation mode of a machine unit, which often lead to the accumulation of fatigue damages in the materials of parts in heavy loaded assemblies. The combination of stationary and nonstationary dynamic loads manifests itself, particularly in drilling rigs, where technological cycles include steady motion modes, starts, and stops. This paper represents a generalized mathematical model describing nonstationary processes in the lift system of a drill rig, which considers the relationship between electromagnetic processes in asynchronous motors and mechanical oscillatory phenomena, with the purpose of determining dynamic loads and stresses in structural elements of the rigs. Nonlinear physical systems include mechanical members with both concentrated and clearly expressed distributed parameters. The durability of structural elements is evaluated by means of a computer algorithm for analysis of crack growth rates using the NASGRO equation obtained with the presence of plastic deformation zones. An example of the crown block axis illustrates the influence of nonstationary dynamic processes in drill rigs on the durability of structural elements.

On Klein tunneling of low-frequency elastic waves in hexagonal topological plates

Incident particles in the Klein tunnel phenomenon in quantum mechanics can pass a very high potential barrier. Introducing the concept of tunneling into the analysis of phononic crystals can broaden the application prospects. In this study, the structure of the unit cell is designed, and the low frequency (< 1 kHz) valley locked waveguide is realized through the creation of a phononic crystal plate with a topological phase transition interface. The defect immunity of the topological waveguide is verified, that is, the wave can propagate along the original path in the cases of impurities and disorder. Then, the tunneling phenomenon is introduced into the topological valley-locked waveguide to analyze the wave propagation, and its potential applications (such as signal separators and logic gates) are further explored by designing phononic crystal plates. This research has broad application prospects in information processing and vibration control, and potential applications in other directions are also worth exploring.

Topology optimization of chiral metamaterials with application to underwater sound insulation

Chiral metamaterials have been proven to possess many appealing mechanical phenomena, such as negative Poisson’s ratio, high-impact resistance, and energy absorption. This work extends the applications of chiral metamaterials to underwater sound insulation. Various chiral metamaterials with low acoustic impedance and proper stiffness are inversely designed using the topology optimization scheme. Low acoustic impedance enables the metamaterials to have a high and broadband sound transmission loss (STL), while proper stiffness guarantees its robust acoustic performance under a hydrostatic pressure. As proof-of-concept demonstrations, two specimens are fabricated and tested in a water-filled impedance tube. Experimental results show that, on average, over 95% incident sound energy can be isolated by the specimens in a broad frequency range from 1 kHz to 5 kHz, while the sound insulation performance keeps stable under a certain hydrostatic pressure. This work may provide new insights for chiral metamaterials into the underwater applications with sound insulation.

A Short Note on Physics-Guided GAN to Learn Physical Models without Gradients

This study briefly describes the concept of guided training of deep neural networks (DNNs) to learn physically reasonable solutions. The proposed method does not need the gradients of the physical equations, although the conventional physics-informed models need the gradients. DNNs are widely used to predict phenomena in physics and mechanics. One of the issues with DNNs is that their output does not always satisfy physical equations. One approach to consider with physical equations is adding a residual of the equations into the loss function; this is called physics-informed neural network (PINN). One feature of PINNs is that the physical equations and corresponding residuals must be implemented as part of a neural network model. In addition, the residual does not always converge to a small value. The proposed model is a physics-guided generative adversarial network (PG-GAN) that uses a GAN architecture, in which physical equations are used to judge whether the neural network’s output is consistent with physics. The proposed method was applied to a simple problem to assess its potential usability.

A Method of Precise Auto-Calibration in a Micro-Electro-Mechanical System Accelerometer.

A novel design of a MEMS (Micro-Electromechanical System) capacitive accelerometer fabricated by surface micromachining, with a structure enabling precise auto-calibration during operation, is presented. Precise auto-calibration was introduced to ensure more accurate acceleration measurements compared to standard designs. The standard mechanical structure of the accelerometer (seismic mass integrated with elastic suspension and movable plates coupled with fixed plates forming a system of differential sensing capacitors) was equipped with three movable detection electrodes coupled with three fixed electrodes, thus creating three atypical tunneling displacement transducers detecting three specific positions of seismic mass with high precision, enabling the auto-calibration of the accelerometer while it was being operated. Auto-calibration is carried out by recording the accelerometer indication while the seismic mass occupies a specific position, which corresponds to a known value of acting acceleration determined in a pre-calibration process. The diagram and the design of the mechanical structure of the accelerometer, the block diagram of the electronic circuits, and the mathematical relationships used for auto-calibration are presented. The results of the simulation studies related to mechanical and electric phenomena are discussed.

Water Evaporation as an Electromagnetic Phenomenon

Water evaporation is currently perceived as a predominantly mechanical phenomenon. This perception is due to the predominance of views based on classical thermodynamics, using the concept of an ideal gas, and, consequently, on molecular kinetic theory. Therefore, the fact that water vapor is always positively charged is perceived as a curiosity. Since this approach is unsatisfactory, it is proposed here to perceive the evaporation of water as a phenomenon caused by the electromagnetic forces of the Earth. In this regard, it is proposed here to take into account the existence of an upward Lorentz force arising as a result of the daily movement of the earth’s surface relative to the geomagnetic field lines. The productivity of this perception of water evaporation is shown here.

The Application of Spectroscopic Parameters for Computing the Energy Spectrum of Selected Diatomic Molecules (VH, LiH, TiC and CuLi)

A basic theoretical model known as the Schrodinger equation is utilized to explain the physics of the waveform, a phenomenon in quantum mechanics. The whole characterization of a technique’s components is included within the wave function. There are several aspects of the Schrodinger equation’s numerical solution. In this work, we determined mathematically the eigenvalues and characteristic functions of the Eckart-Hellmann potential. This study adopted an estimating strategy for solving the problem recommended by the Nikiforov–Uvarov approach and employed the Greene–Aldrich approximation. The aim was determining bound energies and applying the findings to particular diatomic molecules and their spectroscopic parameters. By contrasting our eigenvalue data with extra numerical data collected by other scholars, the good outcomes of our technique were validated.

A Theory of Justice and Social Mechanics

In this article, I argue that Aristotle, a universal philosopher who analysed both natural and social worlds, suggested a groundwork for a theory of justice, which is a fertile soil for a broader social perspective. Such categories as the social order, free will, law, policy choices, and the state are naturally flowing from his brief passage on justice in his Nichomachean Ethics. I assert that all of them are phenomena of turbulent social mechanics. Therefore, in this paper I introduce Aristotle’s contribution to the mainstream theory of justice and then, loosely relying on the works of Aristotle and Newton, I develop a theory of justice in the context of social mechanics. I conclude that the concept of justice is essentially the same as Newton’s third law of mechanics. For this purpose, I employ interdisciplinary and functional approaches, textual and conceptual analysis,and the method of deduction.

Analysis of Electron Double Barrier Tunneling Based on Python

Tunneling is a common phenomenon in microphysics, and resonant tunneling is a tunneling phenomenon under special conditions. Double barrier tunneling is an important quantum mechanical phenomenon, which has important application and research value in condensed matter physics, semiconductor devices, quantum mechanics, and nanotechnology. This study takes the double barrier as an example to observe electron tunneling and find out the influence of different parameters on the tunneling effect. In this study, the wave function is calculated by using the method of Schrodinger equation and transpose matrix, and the image is drawn by Python and numerical operation. In this study, it is found that the barrier width is inversely proportional to the transmittance, and the transmittance and reflectance will change periodically with the distance between the two barriers, and the electrons will reach full transmission at a certain incident energy value. Studying the characteristics and mechanisms of double barrier tunneling helps develop new quantum technologies and devices and promotes technological innovation in related fields.

Brake Wear and Airborne Particle Mass Emissions from Passenger Car Brakes in Dynamometer Experiments Based on the Worldwide Harmonized Light-Duty Vehicle Test Procedure Brake Cycle

Brake wear particles, as the major component of non-exhaust particulate matter, are known to have different emissions, depending on the type of brake assembly and the specifications of the vehicle. In this study, brake wear and wear particle mass emissions were measured under realistic vehicle driving and full friction braking conditions using current commercial genuine brake assemblies. Although there were no significant differences in either PM10 or PM2.5 emissions between the different cooling air flow rates, brake wear decreased and ultrafine particle (PM0.12) emissions increased with the increase in the cooling air flow rate. Particle mass measurements were collected on filter media, allowing chemical composition analysis to identify the source of brake wear particle mass emissions. The iron concentration in the brake wear particles indicated that the main contribution was derived from disc wear. Using a systematic approach that measured brake wear and wear particle emissions, this study was able to characterize correlations with elemental compositions in brake friction materials, adding to our understanding of the mechanical phenomena of brake wear and wear particle emissions.

A review on modeling of graphene and associated nanostructures reinforced concrete

Abstract Concrete is the most popular construction material in infrastructure projects due to its numerous natural advantages. Nevertheless, concrete constructions frequently suffer from low tensile strength and poor durability performance which are always urgent tasks to be solved. The concrete reinforced by various nanomaterials, especially graphene and its associated nanostructures (GANS), shows excellent chemical and physical properties for engineering applications. The influence of GANS on cement composites is a multiscale behavior from the nanoscale to the macroscale, which requires a number of efforts to reveal via numerical and experimental approaches. To meet this need, this study provides a comprehensive overview of the numerical modeling for GANS reinforced concrete in various scales. The background and importance of the topic are addressed in this study, along with the review of its methodologies, findings, and applications. Moreover, the study critically summarizes the performance of GANS reinforced concrete, including its mechanical behavior, transport phenomena, and failure mechanism. Additionally, the primary challenges and future prospects in the research field are also discussed. By presenting an extensive overview, this review offers valuable insights for researchers and practitioners interested in numerical simulation to advance concrete science and engineering.

Non-Hermitian Casimir effect of magnons

There has been a growing interest in non-Hermitian quantum mechanics. The key concepts of quantum mechanics are quantum fluctuations. Quantum fluctuations of quantum fields confined in a finite-size system induce the zero-point energy shift. This quantum phenomenon, the Casimir effect, is one of the most striking phenomena of quantum mechanics in the sense that there are no classical analogs and has been attracting much attention beyond the hierarchy of energy scales, ranging from elementary particle physics to condensed matter physics, together with photonics. However, the non-Hermitian extension of the Casimir effect and the application to spintronics have not yet been investigated enough, although exploring energy sources and developing energy-efficient nanodevices are its central issues. Here we fill this gap. By developing a magnonic analog of the Casimir effect into non-Hermitian systems, we show that this non-Hermitian Casimir effect of magnons is enhanced as the Gilbert damping constant (i.e., the energy dissipation rate) increases. When the damping constant exceeds a critical value, the non-Hermitian Casimir effect of magnons exhibits an oscillating behavior, including a beating one, as a function of the film thickness and is characterized by the exceptional point. Our result suggests that energy dissipation serves as a key ingredient of Casimir engineering.

Elastic strain-induced amorphization in high-entropy alloys

Elastic stability is the basis for understanding structural responses to external stimuli in crystalline solids, including melting, incipient plasticity and fracture. In this work, elastic stability is investigated in a series of high-entropy alloys (HEAs) using in situ mechanical tests and atomic-resolution characterization in transmission electron microscopy. Under tensile loading, the HEA lattices are observed to undergo a sudden loss of ordering as the elastic strain reached ∽ 10%. Such elastic strain-induced amorphization stands in intrinsic contrast to previously reported dislocation-mediated elastic instability and defect accumulation-mediated amorphization, introducing a form of elastic instability. Together with the first principle calculations and atomic-resolution chemical mapping, we identify that the elastic strain-induced amorphization is closely related to the depressed dislocation nucleation due to the local atomic environment inhomogeneity of HEAs. Our findings provide insights for the understanding of the fundamental nature of physical mechanical phenomena like elastic instability and incipient plasticity.

Investigations on Transient Temperature Distribution and Distortion in Shielded Metal Arc Welding of SA 516 Gr. 70 Steel

Efforts are made in this article to investigate the thermal and mechanical phenomena by presenting a coupled thermal and structural analysis of SA516 Grade-70 steel. This material has wide applicability in the fabrication of pressure vessels, boilers, etc., due to its excellent weldability and formability. An actual ongoing problem from a reputed industry, related to distortion during the shielded metal arc welding process, is considered and experiments are carried out on the chosen steel. Results are evaluated employing a two- step methodology, involving simulation. The first step encompasses thermal analysis, providing insights into transient temperature distribution, while the subsequent mechanical analysis offers data on residual stresses and distortion. In the case of heat input, a volumetric heat source with double ellipsoidal heat distribution is used whereas a plasticity material model with rate-independent bilinear kinematic hardening is adopted for the structural analysis. Additionally, temperature-dependent material properties are factored into both scenarios. The data derived from numerical analysis align closely with experimental findings, presenting valuable insights for fabricating industries.

Simulation of the Performance of Kevlar Impregnated Shear Thickening Fluid Ballistic Test Results (STF) Ballistic Test Results

This study explores the enhancement of Kevlar fabric’s ballistic performance through impregnation with Shear Thickening Fluid (STF) for potential application in soft body armor. The experimental approach often fails to elucidate mechanical phenomena critical for the development of lightweight and high-strength body armor designs. To address this limitation, the finite element method, specifically using ANSYS/LS-DYNA R.13, was employed for a comprehensive analysis. The simulation aimed to evaluate the impact of STF on Kevlar fabric by assessing projectile velocity, force exerted by the projectile onto the fabric, displacement, stress distribution, and fabric failure mechanisms. Kevlar yarn was modeled as a shell element formed into fabric with a sine wave profile, investigating two types of STF: SiO2-PEG200 (S0) and SiO2-PEG200-B4C (S1), differing in maximum viscosities. The addition of STF resulted in increased coefficients of friction on Kevlar, with the highest values observed for the SiO2-PEG200-B4C impregnated fabric ( =0.87 and =0.82). The incorporation of the second STF type (S1) significantly reduced the projectile’s velocity from an initial 200 m/s to 153.2 m/s upon impact. Additionally, the force on the S1 fabric surged to 121,556 N, a threefold increase compared to neat Kevlar. STF's influence was further evidenced by enhanced fabric displacement and more uniform stress distribution upon ballistic impact. The fabric's thickening upon failure indicated STF's ability to enlarge the deformation area, facilitating uniform distribution of ballistic kinetic energy across the impact zone. Notably, the fabric impregnated with the second type of STF, featuring boron carbide (S1), demonstrated superior ballistic performance. This study concludes that STF-impregnated Kevlar fabric, particularly the SiO2-PEG200-B4C variant, not only surpasses the ballistic performance of neat Kevlar but also meets the criteria for NIJ Level IIIA standards, highlighting its potential as a highly effective material for advanced soft body armor designs.

The Double-slit Experiment in The Six-dimensional Space-Time

Young's two-slit test can be interpreted over time. Classical events have a quantum behaviour over time. Based on the findings of this research, Quantum Phenomena have a classical interpretation. The role of time has been neglected in the understanding of quantum mechanics phenomena. By examining classical events over time, Quantum Phenomena were simulated. Entanglement, particle-wave phenomenon, etc. are intertwined in the space-time structure. The role of the arrow of time in solving physics problems can be considered.