Computational Elements Research Articles

Study on blade vibration of centrifugal compressor - Forced responses caused by casing treatment

A casing treatment of centrifugal compressor for turbochargers is a very important device in aerodynamic performance improvement because it enables to expand an operating range of compressor. However, a rib existing in the circulation flow path of casing treatment is one of the factors causing a resonance problem. In this study, the relationship between a casing treatment and blade vibration was investigated by frequency response analysis that combines computational fluid dynamics and finite element method. As a result, it was clarified that the difference in the amount of vibration response and the excitation mechanism by the existence of rib.

Improving Software Defined Network controllers in a multi-vendor environment

Software Defined Networking (SDN) is an emerging networking paradigm with the potential to foster innovation through programmable networks. SDNs are characterized by the separation of control and data planes where, in a logically centralized controller, it's possible to make routing decisions on behalf of forwarding elements. For this, there are different protocols proposed and used like Open Flow, Forward and Control Element Separation (FORCES), Path Computation Element Protocol (PCEP), Network Configuration Protocol (NETCONF), and Interface to Routing System (IRS), among others. Border Gateway Protocol (BGP) is one such protocol that enables the network programmability promised by SDNs. The controllers used in BGP as control plane protocols leverage RESTCONF (RFC 8040) as management plane protocol to interact with physical routers, switches, and network service firewalls. Therefore, the aim of this work is to improve the performance of SDN controllers using BGP enabling a multi-vendor environment without requiring infrastructure upgrade showcasing how interoperability can be achieved. The proposed system is implemented using OpenDaylight controllers. The performance of the prototype is evaluated using Latency, Throughput, CPU consumption, and TTL (Time to Live). Based on the simulation results it is observed that the SDN controllers that use BGP show average throughput of 49.6 Gbps, maximum latency of 7 μs, and average CPU consumption 89% and maximum TTL value of 600 msec. The overall performance of the proposed system shows better results when compared with previous works.

Security enhancement of cyber-physical system using modified encryption AESGNRSA technique

<span>A cyber-physical system (CPS) is a combination of physical components with computational elements to interact with the physical world. The integration of these two systems has led to an increase in security concerns. Traditional encryption algorithms designed for general-purpose computing environments may not adequately address the distinct challenges of CPS, such as limited processing power, delay, and resource-constrained hardware. Therefore, there is a pressing need to develop an encryption algorithm that is optimized for CPS security without compromising the critical real-time aspects of these systems. This research has designed a modified encryption technique named the advanced encryption standard in galois counter mode with nonce and rivest-shamir-adleman algorithm (AESGNRSA). A smart medical system is designed to monitor the health of remotely located patients. The AESGNRSA algorithm is applied to the three servers of this system. The data of 1.5 lakh patients is fed to this system to verify the effectiveness of the AESGNRSA algorithm. The performance parameters like encryption and decryption time, encryption and decryption throughput, and encrypted file size are calculated for the AESGNRSA algorithm. The comparative analysis proved that AESGNRSA has the highest performance as compared to other algorithms and it can protect CPS against many cyber-attacks.</span>

All dielectric metasurface based diffractive neural networks for 1-bit adder

Abstract Diffractive deep neural networks (D 2 NNs) have brought significant changes in many fields, motivating the development of diverse optical computing components. However, a crucial downside in the optical computing components is employing diffractive optical elements (DOEs) which were fabricated using commercial 3D printers. DOEs simultaneously suffer from the challenges posed by high-order diffraction and low spatial utilization since the size of individual neuron is comparable to the wavelength scale. Here, we present a design of D 2 NNs based on all-dielectric metasurfaces which substantially reduces the individual neuron size of net to scale significantly smaller than the wavelength. Metasurface-based optical computational elements can offer higher spatial neuron density while completely eliminate high-order diffraction. We numerically simulated an optical half-adder and experimentally verified it in the terahertz frequency. The optical half-adder employed a compact network with only two diffraction layers. Each layer has a size of 2 × 2 cm2 but integrated staggering 40,000 neurons. The metasurface-based D 2 NNs can further facilitate miniaturization and integration of all optical computing devices and will find applications in numerous fields such as terahertz 6G communication, photonics integrated circuits, and intelligent sensors.

Conservation Voltage Reduction Impact Investigation for Personal Computing Devices Using Experimental Measurements and Computation Performance Metrics

Conservation Voltage Reduction (CVR) is a potential energy management approach for increasing computer system energy efficiency. This study uniquely contributes to the field by thoroughly investigating the impact of CVR on computing devices, filling a significant gap in the existing literature. The research employs a novel experimental approach, considering the temporal variations in energy use behavior, and presents a comprehensive benchmark analysis of desktop PCs and laptops. Notable gains in processing efficiency are observed, with specific instances such as Desktop 1’s 1.53% Single-Core performance improvement and Desktop 3’s 3.19% total performance boost. Despite variations, the thermal performance of CVR-equipped devices, particularly Desktop 3 and Laptop 3, consistently demonstrates lower temperatures, indicating thermal management enhanced by 3.19% and 1.35%, respectively. Additionally, the study introduces the CVR Performance Enhancement Ratio (%), providing a unique metric for evaluating the trade-offs between energy efficiency and system performance. This research highlights the dual impact of CVR on thermal and computational elements, emphasizing its broad advantages. Integrating CVR emerges as a viable strategy for developing more durable, efficient, and sustainable computing devices, setting the stage for advancements in voltage regulation.

Super-quadric CFD-DEM modelling of chip-like particle-liquid flow in a rotary drum

The rotary drum is a useful reactor in leaching processes, yet the internal multi-phase flow hydrodynamics still lacks detailed understanding, especially for chip-like particles. This work studies the transportation mechanism of chip-like particles in a particle-liquid rotary drum by the computational fluid dynamics-discrete element method (CFD-DEM) approach where particle morphology is described by a super-quadric model. After model validations, the particle-scale information (e.g., active-passive interface, mixing, dispersion, orientation, and contact force) under different rotating speeds is analyzed. The results show that two anti-directional recirculation liquid vortexes are captured in the rotary drum due to the shear of the bed surface. The active depth, mixing degree, and axial particle dispersion increase with the rotating speed. Chip-like particles tend to orient their long axes parallel to the drum wall and drum axis. The fundamental study sheds light on the design and optimization of rotary drums for mixing and leaching processes.

Fretting wear assessment in PHWR pressure tubes using transient dynamic FEA and Archard’s wear model

In Pressurized Heavy Water Reactors (PHWRs), the fuel bundles are placed in a pressure tube (PT). These bundles rest on inside of pressure tubes through the bearing pads. The pressure tubes are part of the primary pressure boundary of the reactor, and are crucial from functionality and safety point of view. Any phenomena/ factors that may cause structural degradation of PT and may affect its structural integrity, requires thorough investigation. The fretting of pressure tube at bearing pad locations is one such phenomenon, wherein the local material removal due to fretting may lead to stress concentration and associated structural degradations. Therefore, a detailed assessment of the PT fretting damage incurred during its intended life is required. Present paper covers the premise and methodology based on Archard’s wear model for evaluation of the volumetric wear rate of pressure tube. A case study has been done to evaluate the fretting wear in pressure tubes of a large Indian PHWR. 3D transient computational fluid dynamic analysis and finite element analysis with contact modelled between the fuel bundle bearing pads and pressure tube are carried out to evaluate the contact force and sliding distance time histories. Based on the analyses results, the work rate and average saturated fret depth are evaluated. The assessment revealed insignificant concern owing to the fretting of pressure tube for the considered cases.

Finite Element Analysis for NEG coated vacuum chamber based on ANSYS Workbench

The Hefei Advanced Light Facility (HALF) is a diffraction limited storage ring (DLSR) being constructed. As the main component of the storage ring vacuum system, the vacuum chamber transports the beam and withstands the thermal effect of synchrotron radiation simultaneously. The thermal and mechanical condition of the vacuum chamber of HALF were quantitatively analysed by means of ANSYS Workbench in this work. Combining the Computational Fluid Mechanics (CFD) and Finite Elements Analysis (FEA), the temperature and thermal stress maps of the vacuum chamber were calculated. The CFD calculation displays that the heat transfer coefficient between the water and the chamber is 7966-13093 W/(m2·°C). The thermal-mechanical simulation shows that the maximum temperature and thermal stress are 53.5 °C and 42.1 MPa, respectively. The static structural analysis was performed on vacuum chamber under the ultra-high vacuum condition, with the maximum stress of 1.7 MPa and the maximum deformation of 0.0003 mm. These results show that the vacuum chamber meets the design requirements and provide a critical theoretical basis for the design of the vacuum system of HALF.

Super-quadric CFD-DEM study of spout deflection behaviour of non-spherical particles in a spout fluidized bed

Non-spherical particles are commonly encountered in chemical engineering processes including fluidization processes, yet their instability phenomena still lack understanding. In this study, the spout deflection – a typical instability phenomenon of non-spherical particles in a pseudo-two-dimensional (pseudo-2D) spout fluidized bed is first studied by a super-quadric computational fluid dynamics-discrete element method (super-quadric CFD-DEM) model. The intensity of spout deflection is quantified by the spout deflection angle concept. The effect of particle shape (i.e., sphere, cubic, ellipsoid, and cylinder) on the flow in terms of flow pattern, spout deflection, pressure drop, particle orientation, and normal contact force is systematically studied and compared by the time- and frequency-domain analysis. It shows that the spout channel becomes narrower for cubic, ellipsoid and cylinder particles where the particle aspect ratio increases. With the increase of spouting gas velocity, the median value of the spout deflection angle decreases and increases for cubic and ellipsoid particles, respectively. Furthermore, the pressure drops in the vertical and horizontal directions of the cubic, ellipsoid, and cylinder particles are different from each other. At last, In the bed of cubic particles, the ordered arrangements appear close to the wall region and random arrangements occur in the other regions. This work reveals the influences of non-spherical particles on spout deflection and offers insights into practical applications through optimal operation.

Method of treatment and visualization of brain tumor according to MRI data

A computational technique is proposed in which 2D segmentation is carried out using MRI data to prepare the formation of a 3D model of a brain tumor. The proposed technique is based on: pre-processing of MRI images to reduce noise; increasing brightness and contrast; formation of contours of objects of interest and visualization of the studied areas. The core computational element of the contouring and color coding technique is the Shearlet transform for magnetic resonance imaging (MRI) images.

Galaxy catalogs from the Sage Semi-Analytic Model calibrated on The Three Hundred hydrodynamical simulations: A method to push the limits toward lower mass galaxies in dark matter only clusters simulations

The new generation of upcoming deep photometric and spectroscopic surveys will allow us to measure the astrophysical properties of faint galaxies in massive clusters. This would demand to produce simulations of galaxy clusters with better mass resolution than the ones available today if we want to make comparisons between the upcoming observations and predictions of cosmological models. But producing full-physics hydrodynamical simulations of the most massive clusters is not an easy task. This would involve billions of computational elements to reliably resolve low mass galaxies similar to those measured in observations. On the other hand, dark matter only simulations of cluster size halos can be done with much larger mass resolution but at the cost of having to apply a model that populate galaxies within each of the subhalos in these simulations. In this paper we present the results of a new set of dark matter only simulations with different mass resolutions within the The Three Hundred project. We have generated catalogs of galaxies with stellar and luminosity properties by applying the Sage Semi-Analytical Model of galaxy formation. To obtain the catalogs consistent with the results from hydrodynamical simulations, the internal physical parameters of Sage were calibrated with the Particle Swarm Optimization method using a subset of full-physics runs with the same mass resolution than the dark matter only ones.

ФОРМИРОВАНИЕ ИНТЕЛЛЕКТУАЛЬНОЙ ГОТОВНОСТИ ДОШКОЛЬНИКОВ ПОСРЕДСТВОМ КОМПЬЮТЕРНЫХ ИГР

The purpose of the article is to consider the problem of the formation of intellectual readiness for school education of older preschool children using computer games. The article reveals the main provisions of the problem of the formation of intellectual readiness for school in preschool age, examines the importance of computer games in the formation of intellectual readiness in senior preschool age, analyzes the pedagogical conditions for the use of computer games in the formation of intellectual readiness of preschoolers from various sources. As a result, three stages of the study are identified and characterized. In the course of the conducted pedagogical experiment, the initial level of intellectual readiness of older preschool children is determined and described. Taking into account the results obtained, elements of educational and developmental elements of computer games and exercises are being developed, and the implementation of work on the formation of intellectual readiness for school in older preschool children using these games in kindergarten conditions is described. The control stage of the experiment allowed us to determine the dynamics in the formation of intellectual readiness of older preschoolers of the control and experimental groups after the implementation of the developed computer elements of the games. Based on the results of the study, the analysis and interpretation of the results were carried out. The scientific novelty of the research lies in the development of elements of computer games and their introduction into the educational process of kindergarten in order to more effectively form the intellectual readiness of children for school. The article substantiates the effectiveness of the use of educational and developmental elements of computer games in the pedagogical process for the formation of intellectual readiness to study at school at the stage of preschool education.

How much partiality is needed for a theory of computability?

Partiality is a natural phenomenon in computability that we cannot get around. So, the question is whether we can give the areas where partiality occurs, that is, where non-termination happens, more structure. In this paper we consider function classes which besides the total functions only contain finite functions whose domain of definition is an initial segment of the natural numbers. Such functions appear naturally in computation. We show that a rich computability theory can be developed for these functions classes which embraces the central results of classical computability theory, in which all partial (computable) functions are considered. To do so, the concept of a Gödel number is generalised, resulting in a broader class of numberings. The central algorithmic idea in this approach is to search in enumerated lists. In this way, function computability is reduced to set listability. Besides the development of a computability theory for the functions classes, the new numberings – called quasi-Gödel numberings – are studied from a numbering-theoretic perspective: they are complete, and each of the function classes numbered in this way is a retract of the Gödel numbered set of all partial computable functions. Moreover, the Rogers semi-lattice of all computable numberings of the considered function classes is studied and results as in the case of the computable numberings of the partial computable functions are obtained. The function classes are shown to be effectively given algebraic domains in the sense of Scott–Ershov. The quasi-Gödel numberings are exactly the admissible numberings of the computable elements of the domain. Moreover, the domain can be computably mapped onto every other effectively given one so that every admissible numbering of the computable domain elements is generated by a quasi-Gödel numbering via this mapping.

Study of the blocking mechanism in gravel packing based on CFD-DEM

Gravel packing sand control (GPSC), as the optimization of mechanical sand control technology, is widely used in the deep water completion and sand control of loose sandstone heavy oil reservoirs and highly argillaceous. To explore the blocking mechanism of GPSC, the influence of its structural parameters on the blocking of GPSC is investigated. This paper establishes a particle element model based on computational fluid dynamics-discrete element method coupling using the discrete element method and establishes a fluid flow model combined with computational fluid dynamics to realize their full coupling solution. And sand control experiments were carried out using a micro visual sand control simulation device to verify the blocking model. The blocking mechanism is analyzed from the microscopic point of view, and then, the influence of sand control structure parameters on the blocking in GPSC design is evaluated. The results show the following: (1) the blocking process of GPSC can be divided into three stages: an initial stage, sand accumulation stage, and equilibrium stage. (2) There are two main types of gravel packing blockage. The first type of blocking is blocking on the surface of the gravel layer. Sand particles on the surface of gravel layer mainly exist in the form of large particle size blocking gravel pores and sand particles bridging each other. The second type of blockage is the blockage inside the gravel layer. Sand particles mainly exist in the form of internal mud cakes and adsorption on gravels inside the gravel layer. (3) To ensure the sand control performance of the gravel layer, the gravel layer thickness is designed between 23 and 28 mm. The displacement or pressure of the on-site packing pump should be increased to ensure that the gravel layer packing solidity ranges between 59% and 62%. In the design of GPSC, it should be ensured that the median particle size of gravel is 5–6 times the median particle size of sand. This study provides an effective technical reference for the design of gravel structural parameters in on-site gravel packing completion sand control.

Computational modelling of gas–liquid–solid multiphase free surface flow with and without evaporation

Gas–liquid–solid multiphase systems are ubiquitous in engineering applications, e.g. inkjet printing, spray drying and coating. Developing a numerical framework for modelling these multiphase systems is of great significance. An improved, resolved computational fluid dynamics-discrete element method (CFD-DEM) framework is developed to model the multiphase free surface flow with and without evaporation. An improved capillary force model is developed to compute the capillary interactions for partially floating particles at a free surface. Three well-known benchmark cases, namely drag coefficient calculation, the single sphere settling, and drafting-kissing-tumbling of two particles are conducted to validate the resolved CFD-DEM model. It turns out that the resolved CFD-DEM model developed in this paper can accurately calculate the fluid–solid interactions and predict the trajectory of solid particles interacting with the liquid phase. Numerical demonstrations, namely two particles moving along a free surface when the liquid phase evaporates, and particle transport and accumulations inside an evaporating sessile droplet show the performance of the resolved model.

Numerical investigation of non-uniform temperature fields for proppant and fluid phases in supercritical CO2 fracturing

The non-uniform temperature distribution in supercritical CO2 (Sc-CO2) fracturing influences the density, viscosity, and volume expansion or shrinkage rate of Sc-CO2, impacting proppant migration. This study presents a coupled computational fluid dynamics-discrete element method and heat transfer model to examine the effects of proppant bed shape and the heat transfers of proppant-wall, proppant-fluid, and fluid-wall on the fluid and proppant temperature fields. The Sc-CO2 volume expansion is assessed under various temperature conditions by evaluating the volume-averaged Sc-CO2 density. Several factors, including proppant size, shape, thermal conductivity, concentration, temperature difference, and injection velocity, are carefully analyzed to elucidate their impacts. The findings elucidate the existence of four distinct zones in the fluid temperature field. Each zone exhibits different magnitudes of temperature change under diverse conditions and undergoes dynamic transformations with the development of the proppant bed. The fluid-wall heat transfer and the fluid temperatures in Zones C and D are significantly subject to the fluid injection velocity (governing the heating duration), the temperature difference between fluid and formation (impacting the magnitude of heat flux), and the proppant bed shape (controlling the effective heating area). Additionally, the proppant-wall and proppant-fluid heat transfers determine the temperatures of both the proppant bed and the fluid within Zone B, showing a strong correlation with proppant thermal conductivity, proppant size, injection velocity, and temperature difference. The proposed coupled model provides valuable insights into the temperature distributions and flow behaviors of temperature-dependent fracturing fluids and proppants.

Modeling of permeability impairment dynamics in porous media: A machine learning approach

The prediction of clogging and permeability impairment dynamics in porous media is crucial for the optimization of various industrial and natural processes. This paper presents a novel machine learning-based approach for predicting the dynamics of throat clogging and permeability impairment due to fine migration within realistic porous media under varying hydro-physical conditions. A Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) numerical framework, employing a four-way coupling scheme, was used to generate the data for training and validation of the Machine Learning Model (MLM). One hundred and twenty distinct CFD-DEM simulations were performed to generate over 190,000 data points, at throat level, for the training of the MLM. Simulation cases encompassing ranges of porous media geometry, fine particle size, flow velocity, fine particle concentration, grains surface roughness, and fines and grains zeta potential. Geometries of porous media were extracted from high-resolution 3D images of natural sand obtained using micro-computed tomography imaging. The developed MLM predicts the temporal evolution of clogged throats and permeability impairment. The MLM was established by connecting three Machine Learning Sub-Models (MLSMs). The first is a throat-classification MLSM; which classifies the throats based on their location and size to identify clogged throats. Subsequently, a pore volume regression MLSM is implemented to identify the pore volume at which each clogged throat becomes clogged. Finally, the permeability impairment regression MLSM predicts the permeability reduction based on the clogged throat's information and pore volumes associated with clogging. The throats classification in the final MLM showed an accuracy of 95% in predicting clogged throats when compared to direct CFD-DEM simulations whereas the prediction of the permeability impairment had an R-squared value of 0.99. The MLM developed in this study stands as a robust framework for precisely quantifying key microscale parameters; where its predictions were used to quantify the significance of altering the hydro-physical parameters on the microscale parameters of the clogging dynamics. The proposed MLM provides an accurate and fast prediction of porous media clogging and permeability impairment dynamics, with potential applications in various industries, including oil and gas, environmental engineering, and material science.

Моделирование эрозионного износа титанового сплава высокоскоростным потоком частиц

Introduction. Predicting solid particle erosion (SPE) in gaseous flow and managing its intensity is still a relevant problem in mechanical engineering. It requires the development of a general modeling methodology, which also depends upon many special cases studying various physical processes. Such studies should also include verification analysis, process parameters and model sensitivity studies. Mainly computational fluid dynamics and finite element analysis (and mesh-free methods such as smooth particle hydrodynamics or similar) are used to simulate the erosion process. Papers focused on CFD simulation of solid particle erosion of metal alloys are widely presented, but most of it is associated with relatively low or medium particle velocities (< 100–150 m/s) and is close to uniform diameter distribution. This paper presents a CFD study of Ti6Al4V titanium alloy SPE at relatively high particle velocities and sufficiently non-uniform unimodal particle diameter distribution. The paper also studies the turbulence model influence and particle shape effect which appears as a “shape factor” coefficient in the particle drag model. Methods. The heterogenous flow simulation was based on the Reynolds-averaged Navier-Stokes formulation, where the particles, according to Euler-Lagrange formulation, were simulated as mathematical points with corresponding properties. The influence of turbulence models, such as k-epsilon standard, RNG k-epsilon, and a relatively new Generalized equation k-omega (GEKO) model and its coefficients were also studied. Oka and DNV erosion models were also compared based on the general sample mass loss and more specific erosion intensity profile criterions. The simulation results were compared to the lab-scale experimental results. Results and discussion. It is shown that neither erosion intensity profile or sample mass loss do not depend upon the turbulence model choice or GEKO parameters variation. As expected, erosion is dependent on the erosion model and its coefficients. A notable influence of the shape factor is shown. As the drag coefficient increased due to the particle shape, the erosion intensity decreased and the erosive profile on the surface also changed due to the changing velocity and diameter distribution of the heterogenous flow. It is expected that such results would be useful not only for erosion prediction in all areas of mechanical engineering, but also for wear management in mechanical assemblies and shot peening / shot peen forming management and simulation.

Depend Ability Analysis on CPS Using Machine Learning Techniques

A Cyber-Physical System (CPS) is an entity that effortlessly monitors and controls physical operations by integrating computational and physical elements. Dependability on the CPS application program and also proposes a real-time analysis approach to CPS application dependability based upon Artificial Intelligence and Machine Learning (ML). For starters, pick complicated networks to determine tips within the system topology on the CPS application process. Unsupervised mastering category by a quick density clustering algorithm to classify the value of nodes could be successfully put on the crucial analysis of nodes in CPS application program as well as help support the setting up of CPS software phone Secondly, a real-time CPS dependability automated internet analysis technique is suggested. Unreliable methods are able to imply big losses, each monetarily in addition to within man's life. On a good mention, CPS has information like the main component of the operation of theirs. The prevalence and availability of information demonstrate a brand-new chance to change the methods within what dependability evaluation continues to be usually performed. This process utilizes printer mastering tips to create an analysis framework, design, and style an internet queuing algorithm, as well as put into action real-time internet evaluation and analysis of CPS dependability. Preventive steps make sure that the device works ordinarily as well as with no interruption, which significantly betters method dependability. Last but not least, simulation final results verify the usefulness of the analysis technique and the broad application prospects of its.

Modeling and simulation credibility assessments of whole-body finite element computational models for use in NASA extravehicular activity applications

Computational finite element (FE) models are used in suited astronaut injury risk assessments; however, these models’ verification, validation, and credibility (VV&C) procedures for simulating injuries in altered gravity environments are limited. Our study conducts VV&C assessments of THUMS and Elemance whole-body FE models for predicting suited astronaut injury biomechanics using eight credibility factors, as per NASA-STD-7009A. Credibility factor ordinal scores are assigned by reviewing existing documentation describing VV&C practices, and credibility sufficiency thresholds are assigned based on input from subject matter experts. Our results show the FE models are credible for suited astronaut injury investigation in specific ranges of kinematic and kinetic conditions correlating to highway and contact sports events. Nevertheless, these models are deficient when applied outside these ranges. Several credibility elevation strategies are prescribed to improve models’ credibility for the NASA-centric application domain.