Статті в журналах з теми "Size reduction of materials – Computer simulation"
Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Size reduction of materials – Computer simulation.
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 статей у журналах для дослідження на тему "Size reduction of materials – Computer simulation".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте статті в журналах для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Tang, L. Q., K. Pochiraju, C. Chassapis, and S. Manoochehri. "A Computer-Aided Optimization Approach for the Design of Injection Mold Cooling Systems." Journal of Mechanical Design 120, no. 2 (June 1, 1998): 165–74. http://dx.doi.org/10.1115/1.2826955.
Анотація:
A methodology is presented for the design of optimal cooling systems for injection mold tooling which models the mold cooling as a nonlinear constrained optimization problem. The design constraints and objective function are evaluated using Finite Element Analysis (FEA). The objective function for the constrained optimization problem is stated as minimization of both a function related to part average temperature and temperature gradients throughout the polymeric part. The goal of this minimization problem is to achieve reduction of undesired defects as sink marks, differential shrinkage, thermal residual stress built-up, and part warpage primarily due to non-uniform temperature distribution in the part. The cooling channel size, locations, and coolant flow rate are chosen as the design variables. The constrained optimal design problem is solved using Powell’s conjugate direction method using penalty function. The cooling cycle time and temperature gradients are evaluated using transient heat conduction simulation. A matrix-free algorithm of the Galerkin Finite Element Method (FEM) with the Jacobi Conjugate Gradient (JCG) scheme is utilized to perform the cooling simulation. The optimal design methodology is illustrated using a case study.
2
Mauromicale, Giuseppe, Alessandro Sitta, Michele Calabretta, Salvatore Massimo Oliveri, and Gaetano Sequenzia. "Integrated Electromagnetic-Thermal Approach to Simulate a GaN-Based Monolithic Half-Bridge for Automotive DC-DC Converter." Applied Sciences 11, no. 18 (September 7, 2021): 8302. http://dx.doi.org/10.3390/app11188302.
Анотація:
New technological and packaging solutions are more and more being employed for power semiconductor switches in an automotive environment, especially the SiC- and GaN-based ones. In this framework, new front-end and back-end solutions have been developed, and many more are in the design stage. New and more integrated power devices are useful to guarantee the performances in electric vehicles, in terms of thermal management, size reduction, and low power losses. In this paper, a GaN-based system in package solution is simulated to assess the structure temperature submitted to a Joule heating power loss. The monolithic package solution involves a half-bridge topology, as well as a driver logic. A novel integrated electromagnetic and thermal method, based on finite element simulations, is proposed in this work. More specifically, dynamic electric power losses of the copper interconnections are computed in the first simulation stage, by an electromagnetic model. In the second stage, the obtained losses’ geometrical map is imported in the finite element thermal simulation, and it is considered as the input. Hence, the temperature distribution of the package’s copper traces is computed. The simulation model verifies the proper design of copper traces. The obtained temperature swing avoids any thermal-related reliability bottleneck.
3
Masoud, Ziyad N., Ali H. Nayfeh, and Nader A. Nayfeh. "Sway Reduction on Quay-side Container Cranes Using Delayed Feedback Controller: Simulations and Experiments." Journal of Vibration and Control 11, no. 8 (August 2005): 1103–22. http://dx.doi.org/10.1177/1077546305056300.
Анотація:
Traditionally, a container crane is modeled as a simple pendulum with either a flexible or a rigid hoisting cable, and a lumped mass at the end of the cable. However, in the case of quay-side container cranes, the actual configuration of the hoisting mechanism is significantly different; it consists typically of a set of four hoisting cables. The cables are hoisted from four different points on a trolley and are attached on the load side to four points on a spreader bar used to lift containers. A controller design based on the actual model will most likely result in a response superior to those based on simple pendulum models. In this paper, we develop a mathematical model of the actual quay-side container crane. A simplified model is then used to obtain the gain and time delay for a delayed feedback controller, which will be used for the control of payload sway oscillation. Performance of the controller is simulated on a 1/10th scale computer model of a 65 ton container crane using the full model. Simulation results are verified experimentally on a 1/10th scale model of the same container crane.
4
Andreotti, Mirco, Dario Bottino-Leone, Marta Calzolari, Pietromaria Davoli, Luisa Dias Pereira, Elena Lucchi, and Alexandra Troi. "Applied Research of the Hygrothermal Behaviour of an Internally Insulated Historic Wall without Vapour Barrier: In Situ Measurements and Dynamic Simulations." Energies 13, no. 13 (July 1, 2020): 3362. http://dx.doi.org/10.3390/en13133362.
Анотація:
The hygrothermal behaviour of an internally insulated historic wall is still hard to predict, mainly because the physical characteristics of the materials composing the historic wall are unknown. In this study, the hygrothermal assessment of an internally thermal insulated masonry wall of an historic palace located in Ferrara, in Italy, is shown. In situ non-destructive monitoring method is combined with a hygrothermal simulation tool, aiming to better analyse and discuss future refurbishment scenarios. In this context, the original U-value of the wall (not refurbished) is decreased from 1.44 W/m2K to 0.26 W/m2K (10 cm stone wool). Under the site specific conditions of this wall, not reached by the sun or rain, it was verified that even in the absence of vapour barrier, no frost damage is likely to occur and the condensation risk is very limited. Authors proposed further discussion based on simulation. The results showed that the introduction of a second gypsum board to the studied technology compensated such absence, while the reduction of the insulation material thickness provides a reduction of RH peaks in the interstitial area by 1%; this second solution proved to be more efficient, providing a 3% RH reduction and the avoidance of further thermal losses.
5
Popov, Oleg, Irina Talovina, Holger Lieberwirth, and Asiia Duriagina. "Quantitative Microstructural Analysis and X-ray Computed Tomography of Ores and Rocks—Comparison of Results." Minerals 10, no. 2 (January 31, 2020): 129. http://dx.doi.org/10.3390/min10020129.
Анотація:
Profound knowledge of the structure and texture of rocks and ores as well as the behavior of the materials under external loads is essential to further improvements in size reduction processes, particularly in terms of liberation size. New analytical methods such as computer tomography (CT) were adopted to improve the understanding of material characteristics in rocks and ores relevant to mineral processing, particular the crushing and grinding and the modelling/simulation thereof. Results obtained on the texture and structure of identical samples of rather different rocks and ores (copper ore, granodiorite, kimberlite) are compared by CT with quantitative results from traditional optical microscopy obtained by quantitative microstructural analysis (QMA). While the two approaches show a good agreement of the results in many areas, the measurements with the two different methods also exhibit remarkable differences in other areas, which are discussed further. In conclusion, both methods have their specific advantages starting from sample preparation to the accuracy of information obtained concerning certain parameters of mode and fabric. While sample preparation is faster with CT and information on special distribution of metal minerals is more reliable, the information on mode, grain size and clustering seem to be more precise with QMA. Based on the results, it can be concluded that both methods are comparable in many areas, but in in the field of spatial distribution, they are merely complementary.
6
Zhang, Shang, Seyedmehdi Karimi, Shahaboddin Shamshirband, and Amir Mosavi. "Optimization Algorithm for Reduction the Size of Dixon Resultant Matrix: A Case Study on Mechanical Application." Computers, Materials & Continua 58, no. 2 (2019): 567–83. http://dx.doi.org/10.32604/cmc.2019.02795.
7
Nguyen, L. T., S. A. Gee, and W. F. v. d. Bogert. "Effects of Configuration on Plastic Package Stresses." Journal of Electronic Packaging 113, no. 4 (December 1, 1991): 397–404. http://dx.doi.org/10.1115/1.2905426.
Анотація:
This paper examines the effects of device and leadframe configurations on the stresses encountered in typical Dual-in-Line plastic packages. The parameters studied include the die size, the die pad size, the location of the die with respect to the die pad center, and the die coating configuration. Special piezoresistive strain gages deposited on dies of varying sizes are used to map the stress profile across the die surfaces after molding. Finite element simulation of these effects is also conducted. Results indicate that the compressive stresses from the molding compounds are governed with diminishing influence by the size of the die. Furthermore, rather high compressive stresses are observed in the vicinity of the edges of large dies. More subtle effects are found for the influence of the die pad size, the aspect ratio of the die, and the extent of the die offsetting with respect to the die pad center. Finally, by surrounding the die with a thin trail of silicone gel to provide for lateral cushioning, stress reduction is slightly more effective than in the standard “glob-top” coating.
8
Grujicic, M., R. Yavari, J. S. Snipes, and S. Ramaswami. "Design optimization of a mine-blast-venting solution for protection of light-tactical-vehicle subjected to shallow-buried underbody mine detonation." Multidiscipline Modeling in Materials and Structures 12, no. 1 (June 13, 2016): 2–32. http://dx.doi.org/10.1108/mmms-11-2014-0058.
Анотація:
Purpose – The purpose of this paper is computer-aided engineering analysis of the recently proposed side-vent-channel concept for mitigation of the blast-loads resulting from a shallow-buried mine detonated underneath a light tactical vehicle. The concept involves the use of side-vent-channels attached to the V-shaped vehicle underbody, and was motivated by the concepts and principles of operation of the so-called “pulse detonation” rocket engines. By proper shaping of the V-hull and side-vent-channels, venting of supersonically expanding gaseous detonation products is promoted in order to generate a downward thrust on the targeted vehicle. Design/methodology/approach – The utility and the blast-mitigation capacity of this concept were examined in the prior work using computational methods and tools which suffered from some deficiencies related to the proper representation of the mine, soil, and vehicle materials, as well as air/gaseous detonation products. In the present work, an attempt is made to remove some of these deficiencies, and to carry out a bi-objective engineering-optimization analysis of the V-hull and side-vent-channel shape and size for maximum reduction of the momentum transferred to and the maximum acceleration acquired by the targeted vehicle. Findings – Due to the conflicting nature of the two objectives, a set of the Pareto designs was identified, which provide the optimal levels of the trade-off between the two objectives. Originality/value – To the authors’ knowledge, the present work is the first public-domain report of the side-vent-channel blast-mitigation concept.
9
Lluesma-Rodríguez, Federico, Temoatzin González, and Sergio Hoyas. "CFD Simulation of a Hyperloop Capsule Inside a Low-Pressure Environment Using an Aerodynamic Compressor as Propulsion and Drag Reduction Method." Applied Sciences 11, no. 9 (April 27, 2021): 3934. http://dx.doi.org/10.3390/app11093934.
Анотація:
One of the most restrictive conditions in ground transportation at high speeds is aerodynamic drag. This is even more problematic when running inside a tunnel, where compressible phenomena such as wave propagation, shock waves, or flow blocking can happen. Considering Evacuated-Tube Trains (ETTs) or hyperloops, these effects appear during the whole route, as they always operate in a closed environment. Then, one of the concerns is the size of the tunnel, as it directly affects the cost of the infrastructure. When the tube size decreases with a constant section of the vehicle, the power consumption increases exponentially, as the Kantrowitz limit is surpassed. This can be mitigated when adding a compressor to the vehicle as a means of propulsion. The turbomachinery increases the pressure of part of the air faced by the vehicle, thus delaying the critical conditions on surrounding flow. With tunnels using a blockage ratio of 0.5 or higher, the reported reduction in the power consumption is 70%. Additionally, the induced pressure in front of the capsule became a negligible effect. The analysis of the flow shows that the compressor can remove the shock waves downstream and thus allows operation above the Kantrowitz limit. Actually, for a vehicle speed of 700 km/h, the case without a compressor reaches critical conditions at a blockage ratio of 0.18, which is a tunnel even smaller than those used for High-Speed Rails (0.23). When aerodynamic propulsion is used, sonic Mach numbers are reached above a blockage ratio of 0.5. A direct effect is that cases with turbomachinery can operate in tunnels with blockage ratios even 2.8 times higher than the non-compressor cases, enabling a considerable reduction in the size of the tunnel without affecting the performance. This work, after conducting bibliographic research, presents the geometry, mesh, and setup. Later, results for the flow without compressor are shown. Finally, it is discussed how the addition of the compressor improves the flow behavior and power consumption of the case.
10
Bottarelli, Michele, and Francisco Javier González Gallero. "Energy Analysis of a Dual-Source Heat Pump Coupled with Phase Change Materials." Energies 13, no. 11 (June 8, 2020): 2933. http://dx.doi.org/10.3390/en13112933.
Анотація:
Installation costs of ground heat exchangers (GHEs) make the technology based on ground-coupled heat pumps (GCHPs) less competitive than air source heat pumps for space heating and cooling in mild climates. A smart solution is the dual source heat pump (DSHP) which switches between the air and ground to reduce frosting issues and save the system against extreme temperatures affecting air-mode. This work analyses the coupling of DSHP with a flat-panel (FP) horizontal GHE (HGHE) and a mixture of sand and phase change materials (PCMs). From numerical simulations and considering the energy demand of a real building in Northern Italy, different combinations of heat pumps (HPs) and trench backfill material were compared. The results show that PCMs always improve the performance of the systems, allowing a further reduction of the size of the geothermal facility. Annual average heat flux at FP is four times higher when coupled with the DSHP system, due to the lower exploitation. Furthermore, the enhanced dual systems are able to perform well during extreme weather conditions for which a sole air source heat pump (ASHP) system would be unable either to work or perform efficiently. Thus, the DSHP and HGHE with PCMs are robust and resilient alternatives for air conditioning.
11
Takahashi, Takayuki, Tomoyoshi Shimobaba, Takashi Kakue, and Tomoyoshi Ito. "Time-Division Color Holographic Projection in Large Size Using a Digital Micromirror Device." Applied Sciences 11, no. 14 (July 7, 2021): 6277. http://dx.doi.org/10.3390/app11146277.
Анотація:
Holographic projection is a simple projection as it enlarges or reduces reconstructed images without using a zoom lens. However, one major problem associated with this projection is the deterioration of image quality as the reconstructed image enlarges. In this paper, we propose a time-division holographic projection, in which the original image is divided into blocks and the holograms of each block are calculated. Using a digital micromirror device (DMD), the holograms were projected at high speed to obtain the entire reconstructed image. However, the holograms on the DMD need to be binarized, thereby causing uneven brightness between the divided blocks. We correct this by controlling the displaying time of each hologram. Additionally, combining both the proposed and noise reduction methods, the image quality of the reconstructed image was improved. Results from the simulation and optical reconstructions show we obtained a full-color reconstruction image with reduced noise and uneven brightness.
12
Jiang, Xiao, and Tat Leung Chan. "A new weighted fraction Monte Carlo method for particle coagulation." International Journal of Numerical Methods for Heat & Fluid Flow 31, no. 9 (February 4, 2021): 3009–29. http://dx.doi.org/10.1108/hff-07-2020-0449.
Анотація:
Purpose The purpose of this study is to investigate the aerosol dynamics of the particle coagulation process using a newly developed weighted fraction Monte Carlo (WFMC) method. Design/methodology/approach The weighted numerical particles are adopted in a similar manner to the multi-Monte Carlo (MMC) method, with the addition of a new fraction function (α). Probabilistic removal is also introduced to maintain a constant number scheme. Findings Three typical cases with constant kernel, free-molecular coagulation kernel and different initial distributions for particle coagulation are simulated and validated. The results show an excellent agreement between the Monte Carlo (MC) method and the corresponding analytical solutions or sectional method results. Further numerical results show that the critical stochastic error in the newly proposed WFMC method is significantly reduced when compared with the traditional MMC method for higher-order moments with only a slight increase in computational cost. The particle size distribution is also found to extend for the larger size regime with the WFMC method, which is traditionally insufficient in the classical direct simulation MC and MMC methods. The effects of different fraction functions on the weight function are also investigated. Originality Value Stochastic error is inevitable in MC simulations of aerosol dynamics. To minimize this critical stochastic error, many algorithms, such as MMC method, have been proposed. However, the weight of the numerical particles is not adjustable. This newly developed algorithm with an adjustable weight of the numerical particles can provide improved stochastic error reduction.
13
Koleda, E. V., S. O. Kireev, M. V. Korchagina, A. V. Efimov, and J. Sperling. "Strength analysis of the TWS 600 plunger pump body in Solid Works Simulation." Advanced Engineering Research 21, no. 1 (April 4, 2021): 71–81. http://dx.doi.org/10.23947/2687-1653-2021-21-1-71-81.
Анотація:
Introduction. The relevance of the presented paper is due to the widespread use of plunger pumps in industrial practice, in particular, in gas and oil production. The quality of working operations and the efficiency of further well operation depend largely on their reliability. The improvement of plunger pumps involves increasing their reliability, increasing their service life, efficiency, downsizing, reduction in weight, labor intensity of installation and repair work. The modernization of the mechanism includes its power study since the found forces are used for subsequent strengthcalculations. Before the appearance of programs for the numerical analysis of solid objects, the analytical solution to theproblem of strength calculation of the high-pressure pump drive frame was a very time-consuming and expensiveprocedure. The situation has changed with the development of computer technologies and the inclusion of the finite element method in the computer-aided design systems. The objective of this work is to perform a strength calculationon the TWS 600 plunger pump body made of 09G2S steel. Materials and Methods. A method for determining the reactions of the crank shaft supports of a high-pressure plungerpump and strength calculation of the drive part housing is developed. The direction and magnitude of the resultingforces and reactions of the supports are determined graphically according to the superposition principle of the forceaction on the supports. Strength calculations were performed using the finite element method in the computer-aided design system Solid Works Simulation. In this case, solid and finite-element models of the body with imposed boundary conditions were used, which were identified during the analysis of the design and the calculation of the forces arising under the pump operation.Results. The reactions in the crankshaft supports are described with account for the forces generated by the plungerdepending on its operating mode and the crank position. The forces acting on each of the plungers and the resultingreactions in each of the supports are determined. The diagrams of stresses and the safety factor are presented, whichprovide assessing the strength of the body and developing recommendations for creating a more rational design.Discussion and Conclusions. As a result of the calculations, we have identified areas of the structure with minimumsafety factors, and areas that are several times higher than the recommended values. This provides optimizing the designunder study through strengthening the first and reducing the thickness of the metal on the second. From the point ofview of weight and size characteristics and maintainability, the results of the strength calculation performed can be used to optimize the design of the pump body under typical operating conditions.
14
Yuxue, Pu, and Shu Pengfei. "Online secondary path modeling method with auxiliary noise power scheduling strategy for multi-channel adaptive active noise control system." Journal of Low Frequency Noise, Vibration and Active Control 38, no. 2 (February 19, 2019): 740–52. http://dx.doi.org/10.1177/1461348419831119.
Анотація:
Accurate model of secondary paths is very crucial for the multi-channel filtered-X least mean square algorithm applied in adaptive active noise control system. The auxiliary random noise technique is popular for online secondary path modeling during adaptive active noise control operation. This paper proposes a simplified variable step-size strategy and an effective auxiliary noise power scheduling strategy for the multi-channel filtered-X least mean square algorithm. Through a defined indirect error signal, the proposed method can guarantee every online secondary path modeling filter has its own exclusive variable step-size strategy to update their coefficients, and every injected noise has its own exclusive scheduling strategy considering all of the corresponding online secondary path modeling filters. The proposed method can improve the adaptive performance and simplifies the complexity of multi-channel adaptive active noise control system. Computer simulations show that the proposed method gives much better noise reduction and secondary path modeling accuracy at a somewhat faster convergence rate comparing with the competing methods.
15
Zhang, Y., P. Zhu, G. L. Chen, and Z. Q. Lin. "Study on Structural Lightweight Design of Automotive Front Side Rail Based on Response Surface Method." Journal of Mechanical Design 129, no. 5 (June 9, 2006): 553–57. http://dx.doi.org/10.1115/1.2712223.
Анотація:
Nowadays, vehicle lightweight design is a main topic in automotive industry. Crashworthiness, which is the most important performance of a full vehicle, must be always satisfied in the study on body lightweight design. This paper presents research, from the point of view of safety, of structural lightweight design of the front side rail of a passenger car. The response surface method is used to create mathematical models that represent the relationship between structural sheet thicknesses and absorbed energy of the entire structure in the frontal crash simulation, and the relationship between structural sheet thicknesses and the mass of the entire structure. Then an optimization process is performed, and the structural mass and original absorbed energy are defined as objective and constraint functions, respectively. Minimum mass and structural sheet thicknesses are obtained with the satisfaction of original absorbed energy of the front side rail structure. The weight reduction of the front side rail is 26.95%.
16
Abdel-Mawgoud, Hussein, Salah Kamel, Marcos Tostado-Véliz, Ehab E. Elattar, and Mahmoud M. Hussein. "Optimal Incorporation of Photovoltaic Energy and Battery Energy Storage Systems in Distribution Networks Considering Uncertainties of Demand and Generation." Applied Sciences 11, no. 17 (September 5, 2021): 8231. http://dx.doi.org/10.3390/app11178231.
Анотація:
In this paper, the Archimedes optimization algorithm (AOA) is applied as a recent metaheuristic optimization algorithm to reduce energy losses and capture the size of incorporating a battery energy storage system (BESS) and photovoltaics (PV) within a distribution system. AOA is designed with revelation from Archimedes’ principle, an impressive physics law. AOA mimics the attitude of buoyant force applied upward on an object, partially or entirely dipped in liquid, which is relative to the weight of the dislodged liquid. Furthermore, the developed algorithm is evolved for sizing several PVs and BESSs considering the changing demand over time and the probability generation. The studied IEEE 69-bus distribution network system has different types of the load, such as residential, industrial, and commercial loads. The simulation results indicate the robustness of the proposed algorithm for computing the best size of multiple PVs and BESSs with a significant reduction in the power system losses. Additionally, the AOA algorithm has an efficient balancing between the exploration and exploitation phases to avoid the local solutions and go to the best global solutions, compared with other studied algorithms.
17
Abdi, Frank, Parviz Yavari, Vasyl Harik, and Cody Godines. "Material Allowable Generation and AM Process Parameters Effect on Porosity." Coatings 10, no. 7 (June 30, 2020): 625. http://dx.doi.org/10.3390/coatings10070625.
Анотація:
Additive manufacturing (AM) process methods such as powder bed fusion (LPBF) of metal powder layers can produce layered material systems with designed microstructures, which may exhibit scatter in mechanical properties (e.g., lower yield and lower failure strain), corrosion due to porosity and print anomalies. This study shows the development of AM process simulation to predict As-built material characteristic and their scatter comparing with experimental test data. ICME (Integrated Computational Materials Engineering) was used to simulate yield, ultimate, strain, and reduction of the area of sample AM. The method was extended to predict oxidation and damage of as-built parts. The samples were fabricated horizontally and vertically in multiple and scatter directions to find the effect on the mechanical properties such as ultimate tensile strength (UTS) and yield strength (YS). The probabilistic sensitivities show that in order for the next-generation technology to improve the strength of 3D printed materials, they must control the void volume fraction (trapped gas) and orientation of voids. The studied 3D print modality processes: (a) LPBF of AlSi10Mg, and (b) Electron Beam (EBM) of Ti-6Al-4V materials are shown to be over 99.99% reliable. The statistics of 3D printed Ti-6Al-4V have been observed for room and high temperature (RT/HT). The ICME Material Characterization and Qualification (MCQ) software material model prediction capabilities were used to predict (a) Material Allowable, a variation in Stress Strain Curves Characteristic Points and Residual Stress due to air particle (void/defect) shape and size and orientation. The probabilistic simulation computes Cumulative Distribution Function (CDF) and probabilistic sensitivities for YS, UTS, and %Elongation as well as A and B basis allowable of the As-Built 3D printed material and; and (b) Fracture Control Plan fracture toughness determination, and fatigue crack growth vs. stress intensity.
18
Guan, Nanxiang, Ao Wang, Yongpeng Gu, Zhifeng Xie, and Ming Zhou. "A Novel Coaxial Balance Mechanism for Reciprocating Piston Engines." Applied Sciences 11, no. 12 (June 18, 2021): 5647. http://dx.doi.org/10.3390/app11125647.
Анотація:
Vibration is an important issue faced by reciprocating piston engines, and is caused by reciprocating inertia forces of the piston set. To reduce the vibration without changing the main structure and size of the original engine, we proposed a novel coaxial balance mechanism design based on a compact unit body. By introducing a second-order balance mass, this mechanism can significantly increase the efficiency of vibration reduction. The proposed mechanism can effectively balance the first-order and second-order inertia forces with the potential of balancing high-order inertia forces. To accurately determine the second-order balance mass, a closed-form method was developed. Simulation results with a single-cylinder piston DK32 engine demonstrate the effectiveness and advantage of the proposed mechanism. At a crankshaft speed of 2350 r/min, compared with the first-order balance device, the average root mean square velocity of the test points on the engine’s cylinder was reduced by 97.31%, and the support reaction force was reduced by 96.54%.
19
Taler, Dawid, and Anna Korzen. "Numerical modeling transient response of tubular cross flow heat exchanger." International Journal of Numerical Methods for Heat & Fluid Flow 28, no. 1 (January 2, 2018): 81–91. http://dx.doi.org/10.1108/hff-10-2016-0406.
Анотація:
Purpose The paper aims to present the mathematical modeling of plate fin and tube heat exchanger at small Reynolds numbers on the water side. The Reynolds number of the water flowing inside the tubes was varied in the range from 4,000 to 12,000. Design/methodology/approach A detailed analysis of transient response was modeled for the following changes in the operating parameters of the heat exchanger: a reduction in the water volume flow, an increase in the water volume flow and an increase in the water volume flow with a simultaneous reduction in the air flow velocity. Findings The results of the numerical simulation of a heat exchanger by using experimentally determined water-side heat transfer correlation and theoretical correlation derived for the transition tube flow agree very well. The relationship to calculate the air-side Nusselt number was determined experimentally. The correlation for the air-side Nusselt number was the same for the theoretical and experimental water side correlation. Research limitations/implications The correlation for the air-side Nusselt number as a function of the Reynolds and Prandtl numbers is based on the experimental data and was determined using the least squares method. Originality/value The form of the relationship that was used to approximate experimentally determined water-side Nusselt numbers is identical to the theoretically derived formula for the transition range. The experiments show that the relationship for the water-side Nusselt number in transition and turbulent flow regime that was obtained using theoretical analysis gives quite satisfactory results.
20
Williams, Z. A., and J. A. Roux. "Graphite Foam Thermal Management of a High Packing Density Array of Power Amplifiers." Journal of Electronic Packaging 128, no. 4 (December 23, 2005): 456–65. http://dx.doi.org/10.1115/1.2353282.
Анотація:
Much focus has been placed on the thermal management of electronics in recent years. An overall reduction in size of electronic components as well as advances in chip technology, leading to ever higher power dissipation, have increased the necessity for innovative cooling designs. While computational fluid dynamics (CFD) software packages have been instrumental in the design of cooling systems, it remains important to validate these CFD predictions through experimentation. The present work focuses on the experimental evaluation of several variations of an air cooled base plate channel design for an array of generic power amplifier modules. In the current study two materials, graphite foam and a microfibrous material, are investigated as mini-heat exchangers to be implemented in the cooling channel of the base plate. Computational simulations have been conducted on some of the proposed designs in order to evaluate certain parameters. Experiments were conducted measuring chip temperatures and the pressure drop across the cooling channel. Effective heat transfer coefficients were also reverse engineered.
21
Umair, Hassan, Tarik Bin Abdul Latef, Yoshihide Yamada, Tayyab Hassan, Wan Nor Liza Binti Wan Mahadi, Mohamadariff Othman, Kamilia Kamardin, and Mousa I. Hussein. "Quarter Wavelength Fabry–Perot Cavity Antenna with Wideband Low Monostatic Radar Cross Section and Off-Broadside Peak Radiation." Applied Sciences 11, no. 3 (January 25, 2021): 1053. http://dx.doi.org/10.3390/app11031053.
Анотація:
Since antennas are strong radar targets, their radar cross section (RCS) reduction and radiation enhancement is of utmost necessity, particularly for stealth platforms. This work proposes the design of a Fabry–Perot Cavity (FPC) antenna which has wideband low monostatic RCS. While in the transmission mode, not only is gain enhancement achieved, but radiation beam is also deflected in the elevation plane. Moreover, the design is low-profile, i.e., the cavity height is ~λ/4. A patch antenna designed at 6 GHz serves as the excitation source of the cavity constructed between the metallic ground plane and superstrate. The superstrate structure is formed with absorptive frequency selective surface (AFSS) in conjunction with dual-sided partially reflective surface (PRS). Resistor loaded metallic rings serve as the AFSS, while PRS is constructed from inductive gradated mesh structure on one side to realize phase gradient for beam deflection; the other side has fixed capacitive elements. Results show that wideband RCS reduction was achieved from 4–16 GHz, with average RCS reduction of about 8.5 dB over the reference patch antenna. Off-broadside peak radiation at −38° was achieved, with gain approaching ~9.4 dB. Simulation and measurement results are presented.
22
Cortellessa, Gino, Fausto Arpino, Simona Di Fraia, and Mauro Scungio. "Two-phase explicit CBS procedure for compressible viscous flow transport in porous materials." International Journal of Numerical Methods for Heat & Fluid Flow 28, no. 2 (February 5, 2018): 336–60. http://dx.doi.org/10.1108/hff-02-2017-0080.
Анотація:
Purpose In this work, a new two-phase version of the finite element-based Artificial Compressibility (AC) Characteristic-Based Split (CBS) algorithm is developed and applied for the first time to heat and mass transfer phenomena in porous media with associated phase change. The purpose of this study is to provide an alternative for the theoretical analysis and numerical simulation of multiphase transport phenomena in porous media. Traditionally, the more complex Separate Flow Model was used in which the vapour and liquid phases were considered as distinct fluids and mathematically described by the conservation laws for each phase separately, resulting in a large number of governing equations. Design/methodology/approach Even though the adopted mathematical model presents analogies with the conventional multicomponent mixture flow model, it is characterized by a considerable reduction in the number of the differential equations for the primary variables. The fixed-grid numerical formulation can be applied to the resolution of general problems that may simultaneously include a superheated vapour region, a two-phase zone and a sub-cooled liquid region in a single physical domain with irregular and moving phase interfaces in between. The local thermal non-equilibrium model is introduced to consider the heat exchange between fluid and solid within the porous matrix. Findings The numerical model is verified considering the transport phenomena in a homogenous and isotropic porous medium in which water is injected from one side and heated from the other side, where it leaves the computational domain in a superheated vapour state. Dominant forces are represented by capillary interactions and two-phase heat conduction. The obtained results have been compared with the numerical data available in the scientific literature. Social implications The present algorithm provides a powerful routine tool for the numerical modelling of complex two-phase transport processes in porous media. Originality/value For the first time, the stabilized AC-CBS scheme is applied to the resolution of compressible viscous flow transport in porous materials with associated phase change. A properly stabilized matrix inversion-free procedure employs an adaptive local time step that allows acceleration of the solution process even in the presence of large source terms and low diffusion coefficients values (near the phase change point).
23
Ruiz-Robles, Dante, Edgar L. Moreno-Goytia, Vicente Venegas-Rebollar, and Nadia M. Salgado-Herrera. "Power Density Maximization in Medium Frequency Transformers by Using Their Maximum Flux Density for DC–DC Converters." Electronics 9, no. 3 (March 11, 2020): 470. http://dx.doi.org/10.3390/electronics9030470.
Анотація:
The medium frequency transformer (MTF) is a key component of various new DC–DC converters that are designed for applications in modern electrical power grids at medium and high voltage. To attain the high performance that are necessary for targeting these applications, MFTs should have high power density and high efficiency as characteristics. For this endeavor, newly designed MFT procedures, which also take advantages of new core materials, are under investigation. Differently to other design proposals, most of which use conventional transformer design procedures based on equating core losses to copper conduction losses, in this paper, an MTF with a nanocrystalline (VITROPERM 500F) core is designed with a new procedure that is oriented in aiming the maximum flux density (Bmax). The characteristics of the MFTs that are obtained by using this procedure are compared with those of the MFTFs that are designed with a conventional procedure. The results show that by using the proposed technique, we get a 25% reduction in the winding size, a higher power density, and a lower MTF building cost while maintaining a high efficiency (>98%). The design methodology is developed through a rigorous mathematical analysis that is verified with computer simulations in Matlab-Simulink and validated with experimental results from two MTF laboratory prototypes designed at a flux density of 0.9 T (75% Bmax) and 1.2 T (Bmax).
24
Zhu, P., Y. Zhang, and G.-L. Chen. "Metamodel-based lightweight design of an automotive front-body structure using robust optimization." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 223, no. 9 (September 1, 2009): 1133–47. http://dx.doi.org/10.1243/09544070jauto1045.
Анотація:
Both conventional automobiles and new energy cars require urgently lightweight design to realize energy economy and environmental protection in a long run. The weight reduction of the body structure plays a rather important role in decreasing the weight of the full vehicle. In real engineering problems, the variation in sheet gauge, geometrical size, and material parameters caused by environmental factors and other uncertainties may affect the structural performances of body components. Therefore, a lightweight design without considering this kind of tolerance may result in the loss of feasibility and reliability in engineering application. From the viewpoint of crashworthiness performance, this paper presents a study on the lightweight design of the automotive front-body structure based on robust optimization, considering the variation in design variables including sheet gauge and yield limit of materials. Coupled with the design and analysis of a computer experiment, four metamodelling techniques, namely support vector regression, kriging, radial basis functions, and artificial neural networks, are employed to build the metamodels of structural crashworthiness performance indicators for comparison of approximation accuracy. An adaptive deterministic optimization process is used to upgrade further the approximation accuracy of metamodels for the following robust optimization. A double-loop strategy is chosen when solving the robust optimization formulation and the basic Monte Carlo simulation method is applied to perform a reliability analysis. A genetic algorithm solver is used to obtain both the deterministic and the robust optimum results for comparison. The reduced weight obtained by using robust optimization is 7.8003kgf (19.45 per cent) and the result achieved from robust optimization is more conservative than that obtained through deterministic optimization as expected. However, the robust optimum design is ensured to be feasible and reliable when the variation in design variables works in a real engineering application.
25
He, Cenlin, Qinbin Li, Kuo-Nan Liou, Ling Qi, Shu Tao, and Joshua P. Schwarz. "Microphysics-based black carbon aging in a global CTM: constraints from HIPPO observations and implications for global black carbon budget." Atmospheric Chemistry and Physics 16, no. 5 (March 9, 2016): 3077–98. http://dx.doi.org/10.5194/acp-16-3077-2016.
Анотація:
Abstract. We develop and examine a microphysics-based black carbon (BC) aerosol aging scheme that accounts for condensation, coagulation, and heterogeneous chemical oxidation processes in a global 3-D chemical transport model (GEOS-Chem) by interpreting the BC measurements from the HIAPER Pole-to-Pole Observations (HIPPO, 2009–2011) using the model. We convert aerosol mass in the model to number concentration by assuming lognormal aerosol size distributions and compute the microphysical BC aging rate (excluding chemical oxidation aging) explicitly from the condensation of soluble materials onto hydrophobic BC and the coagulation between hydrophobic BC and preexisting soluble particles. The chemical oxidation aging is tested in the sensitivity simulation. The microphysical aging rate is ∼ 4 times higher in the lower troposphere over source regions than that from a fixed aging scheme with an e-folding time of 1.2 days. The higher aging rate reflects the large emissions of sulfate–nitrate and secondary organic aerosol precursors hence faster BC aging through condensation and coagulation. In contrast, the microphysical aging is more than 5-fold slower than the fixed aging in remote regions, where condensation and coagulation are weak. Globally, BC microphysical aging is dominated by condensation, while coagulation contribution is largest over eastern China, India, and central Africa. The fixed aging scheme results in an overestimate of HIPPO BC throughout the troposphere by a factor of 6 on average. The microphysical scheme reduces this discrepancy by a factor of ∼ 3, particularly in the middle and upper troposphere. It also leads to a 3-fold reduction in model bias in the latitudinal BC column burden averaged along the HIPPO flight tracks, with largest improvements in the tropics. The resulting global annual mean BC lifetime is 4.2 days and BC burden is 0.25 mg m−2, with 7.3 % of the burden at high altitudes (above 5 km). Wet scavenging accounts for 80.3 % of global BC deposition. We find that, in source regions, the microphysical aging rate is insensitive to aerosol size distribution, condensation threshold, and chemical oxidation aging, while it is the opposite in remote regions, where the aging rate is orders of magnitude smaller. As a result, global BC burden and lifetime show little sensitivity (< 5 % change) to these three factors.
26
Tan, Qingyang, and Liangzong He. "Improved Modulation Strategy Based on Minimum Energy Storage Principle for Electrolytic-Capacitor-Less Six-Switch Converter." Applied Sciences 11, no. 13 (June 25, 2021): 5901. http://dx.doi.org/10.3390/app11135901.
Анотація:
An improved modulation strategy based on minimum energy storage for DC-link capacitance reduction in a six-switch AC-AC converter is proposed. The proposed modulation strategy enables the energy on the capacitor to accumulate and release twice each in a complete switching cycle, achieving the effect of “fast charging and discharging”. Meanwhile, the inversion and rectification are modulated synchronously. Hence, there is minimum energy stored in the DC-link capacitor. Then, the time average modeling analysis is presented to take insight analysis. When there is the same voltage ripples constraint on the DC side for the conventional and improved modulation strategies, the six-switch converter under the improved modulation strategy has the much less capacitance value of the storage capacitor and even realizes non-electrolytic capacitance. Therefore, improving the system efficiency, power density, and output waveform quality and extending the system life can be achieved. The operation principle and modulation strategy are discussed in detail. Finally, the simulation model and experimental prototype are built to verify effectiveness of the topology and correctness of the proposed six-switch AC-AC converter modulation strategy.
27
Sun, Zhenxu, Shuanbao Yao, Lianyi Wei, Yongfang Yao, and Guowei Yang. "Numerical Investigation on the Influence of the Streamlined Structures of the High-Speed Train’s Nose on Aerodynamic Performances." Applied Sciences 11, no. 2 (January 15, 2021): 784. http://dx.doi.org/10.3390/app11020784.
Анотація:
The structural design of the streamlined shape is the basis for high-speed train aerodynamic design. With use of the delayed detached-eddy simulation (DDES) method, the influence of four different structural types of the streamlined shape on aerodynamic performance and flow mechanism was investigated. These four designs were chosen elaborately, including a double-arch ellipsoid shape, a single-arch ellipsoid shape, a spindle shape with a front cowcatcher and a double-arch wide-flat shape. Two different running scenes, trains running in the open air or in crosswind conditions, were considered. Results reveal that when dealing with drag reduction of the whole train running in the open air, it needs to take into account how air resistance is distributed on both noses and then deal with them both rather than adjust only the head or the tail. An asymmetrical design is feasible with the head being a single-arch ellipsoid and the tail being a spindle with a front cowcatcher to achieve the minimum drag reduction. The single-arch ellipsoid design on both noses could aid in moderating the transverse amplitude of the side force on the tail resulting from the asymmetrical vortex structures in the flow field behind the tail. When crosswind is considered, the pressure distribution on the train surface becomes more disturbed, resulting in the increase of the side force and lift. The current study reveals that the double-arch wide-flat streamlined design helps to alleviate the side force and lift on both noses. The magnitude of side force on the head is 10 times as large as that on the tail while the lift on the head is slightly above that on the tail. Change of positions where flow separation takes place on the streamlined part is the main cause that leads to the opposite behaviors of pressure distribution on the head and on the tail. Under the influence of the ambient wind, flow separation occurs about distinct positions on the train surface and intricate vortices are generated at the leeward side, which add to the aerodynamic loads on the train in crosswind conditions. These results could help gain insight on choosing a most suitable streamlined shape under specific running conditions and acquiring a universal optimum nose shape as well.
28
Lee, Pei Yuan, Jiing Yih Lai, Chung Yi Huang, and Yu Sheng Hu. "Computer Assisted Fracture Reduction and Fixation Simulation for Pelvic Fractures." Applied Mechanics and Materials 493 (January 2014): 354–60. http://dx.doi.org/10.4028/www.scientific.net/amm.493.354.
Анотація:
Abstract. The objective of this study is to present an integrated surgical simulation program on a personal computer for the preoperative planning of pelvic fractures. It first provides a visualization module to display 2D images and 3D model simultaneously. A semi-automatic bone segmentation module is then provided to separate the bony structures, enabling the manipulation of individual fractured bone and bone fragment. A bone reduction module is provided for the localization of the fractured bones. The simulation of plate and screw fixation is also presented, which provides useful information for determining the shape and size of the implants. Also, an example with real CT images are presented to demonstrate the feasibility of the proposed method.
29
Kim, Wootaek, Jongchan Noh, and Jinwook Lee. "Effects of Vehicle Type and Inter-Vehicle Distance on Aerodynamic Characteristics during Vehicle Platooning." Applied Sciences 11, no. 9 (April 30, 2021): 4096. http://dx.doi.org/10.3390/app11094096.
Анотація:
Considering the future development in vehicle platooning technology and the multiple models pertaining to complex road environments involving freight cars and general vehicles, the speed and distance of a vehicle model were set as variables in this study. This study aimed at analyzing the effect of currents acting differently using SolidWorks Flow Simulation tool for the vehicle platooning between different models of trucks that are currently being studied actively and sports utility vehicle (SUV) whose market share has been increasing, in order to evaluate the changes in the drag coefficient and their causes. Additionally, purpose-based vehicle (PBV) presented by Hyundai Motor (Ulsan, Korea) during the CES 2020 was considered. In this study, we found that the shape of the rear side of the leading vehicle reduces the drag coefficient of the following vehicle by washing the wake, similar to a spoiler at the rear. The rear side area of the leading vehicle forms a wide range of low pressures, which increases the drag coefficient effect of the following vehicle. The overall height of the leading vehicle also generates a distribution of low pressures above the rear of the vehicle. This reduces the impact of low pressures on the overall height of the following vehicle. The shape of the front of the following vehicle enables the wake of the leading vehicle, which involves low pressures, to inhibit the Bernoulli effect of the following vehicle. Furthermore, the front of the following vehicle continues to be affected by the wake of the leading vehicle, resulting in an increase in the drag coefficient reduction.
30
Stupak, Eugeniuš, and Romualdas Baušys. "GENERATION OF THE UNSTRUCTURED FE-GRIDS FOR COMPLEX 2D OBJECTS/NESTRUKTŪRINIŲ BE TINKLŲ GENERAVIMAS SUDĖTINGIEMS DVIMAČIAMS OBJEKTAMS." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 6, no. 1 (February 28, 2000): 17–24. http://dx.doi.org/10.3846/13921525.2000.10531559.
Анотація:
For the numerical simulation of engineering problems, the finite element method (FEM) is among the most popular approaches. One of the main concerns in a finite element analysis is the adequacy of the finite element grid. The accuracy of the FEM depends on the size, shape and placement of the elements. On the other hand, the total computational cost is determined by the total number of elements in FE model. An increased accuracy can be obtained by the global reduction of the element size, but this can be characterised by drastically increased computational cost. Thus, in many engineering applications it is desirable to generate not regular FE mesh with finer grid in the regions where accuracy of numerical simulation is of most importance and with more coarse grid in the other regions. In this paper we present a new approach to the grid generation of the multimaterial or multidomain engineering systems by the advancing front technique. This technique has proved successful in generating unstructured meshes in two and three dimensions [1–9]. The algorithm of the technique is summarised in section 2. Common for all approaches of advancing front mesh generation is that the generation problem is divided into three parts. First, the specification of the mesh size attributes, second, the discretisation of the boundaries, and, third, the discretisation of the interior of the domain. In the advancing front technique the front is defined as the boundary between the gridded and ungridded region. The key algorithmic step that must be addressed to advancing front methods is the proper introduction of new elements into the ungridded region. For triangular and tetrahedral grids the elements are introduced sequentially one at a time. The most obvious advantage of the advancing front method is that it directly incorporates free form geometry. Direct implementation of the advancing front technique for multimaterial or multidomain engineering applications is still challenging. Grid generation in the place of few materials or domain contact must ensure the compatibility of nodes on common boundary segments (nodes on common boundary segments must be in the same positions). The advancing front technique does not include non-convex domain, so at the first step non-convex domain of discretisation is decomposed into few convex subdomains. The subdomain of interest must be defined by describing a course background mesh of triangle elements, covering the entire multidomain region, which forms the input for finite element analysis. In this work, a black box architecture expert system has been developed which incorporates the information about the object geometry as well as the boundary and loading conditions, distribution of materials characteristics to generate an a priori (before the finite element analysis is carried out) mesh which is more refined around the critical regions (singularities, re-entrant corners, regions with high-stress concentration, etc) of the problem domain. This system uses a new concept of subtracting to locate the critical regions in the domain and to assign priority and mesh size to them. This involves the decomposition of the original structure into substructures (or primitives) for which an initial and approximate analysis can be performed by using analytical solutions and heuristics. When incorporated into and compared with the traditional approach to the adaptive finite element analysis, it is expected that the proposed approach, which starts the process with near optimal meshes, will be more accurate and efficient. Several numerical examples are presented and discussed. Examples demonstrate that our approach enables to generate the compatible meshes for multimaterial or multidomain problems. The quality of meshes is good, there are no ill-shaped elements. By the proposed expert system we can generate the mesh for any complex structure. The generation of 2D meshes is only the first step using the proposed expert system; in future we shall extend it for 3D meshes. During the last decade a lot of research has been devoted to extension of the advancing front technique to the parallel computers [8, 10, 11]. But the application of the technique to parallel processors is still challenging. In fact, we have to solve how to minimise inter-processor communication during mesh generation of subdomains. The proposed expert system for complex structures grid generation enables to use it with parallel computers. At the first step the domain of discretisation is decomposed into subdomains and all the surfaces defining the boundaries of subdomains to be gridded are triangulated. Later all subdomains can be meshed concurrently and no more inter-processor communication is required. The master task sends to workers tasks information about dividing common boundaries and information of each subdomain. The workers tasks receive their subdomain data and mesh their subdomain. Later the master receives the information from the workers tasks and joins gridded subdomains to one structure, ensuring the compatibility of nodes on common boundaries. So this suggested expert system enables to minimise the communications and costs of computations. The implementation of the expert system to parallel processors is to be done in the future.
31
Lai, P. T., and Y. C. Cheng. "Reduction of problem size for the Poisson solver in device simulation." IEEE Electron Device Letters 6, no. 1 (January 1985): 6–7. http://dx.doi.org/10.1109/edl.1985.26023.
32
Boninsegni, Massimo. "Computer Simulation Study of Nanoscale Size Parahydrogen Clusters." Journal of Low Temperature Physics 195, no. 1-2 (December 7, 2018): 51–59. http://dx.doi.org/10.1007/s10909-018-2109-7.
33
Chen, Zhuo, Zhi Xiong Huang, Rong Yang Dou, Jing Dai, Min Xian Shi, and Jia You Ji. "Computer Simulation Model for Multi-Size Spherical Particles Reinforced Composite Materials." Key Engineering Materials 508 (March 2012): 361–64. http://dx.doi.org/10.4028/www.scientific.net/kem.508.361.
Анотація:
In this Research a Method for Computer Simulation Model of Composite Materials, which Are Reinforced by Multi-Size Particles, Is Introduced. All Particles Are Embedded in the Matrix Randomly. Composite of Different Particle Volume Fraction Were Simulated and Visualized. Statistic Results Shows that the Particles Disperse Distribution Are Uniform which Could Be Used in the Further Study of Composite.
34
Zhang, Qingzhu, Guobiao Zuo, Qinghui Lai, Jin Tong, and Zhihong Zhang. "EDEM Investigation and Experimental Evaluation of Abrasive Wear Resistance Performance of Bionic Micro-Thorn and Convex Hull Geometrically Coupled Structured Surface." Applied Sciences 11, no. 14 (July 20, 2021): 6655. http://dx.doi.org/10.3390/app11146655.
Анотація:
Procambarus clarkii was found to have excellent anti-wear performance against abrasive materials. To improve the wear resistance performance of the soil-engaging component of agricultural machinery, in this study, the micro-thorn and convex hull coupled geometrical structured surfaces inspired from the cephalothorax exoskeleton of the Procambarus clarkii was selected as the bionic prototype. By adopting bionic engineering techniques, three types of novel geometrical structured surfaces were proposed, which were bionic single, double and triple micro-thorn coupled convex hull surfaces (Bionic Type 2, 3 and 4, respectively). The anti-abrasive wear properties of these proposed geometrical surfaces were compared with a conventional bionic convex hull structured surface (Bionic Type 1) and a surface without any structures (smooth). Abrasive wear tests were conducted by using a rotational abrasive wear testing system. The accumulative test time was 80 h and the total wear distance was 6.09 × 105 m. By adopting the EDEM software (discrete element modeling), the Archard Wear model was selected to simulate the wear behavior of five different surfaces. In addition, the wear mechanisms of different surfaces were investigated. The results showed that the smooth surface suffered the most severe abrasive were, the abrasion loss reached 194.1 mg. The anti-abrasive properties of bionic geometric structured non-smooth surfaces were greatly improved; the reduction in terms of abrasion losses ranged between 20.4% and 94.1%, as compared with the smooth surface. The wear resistance property of micro-thorn and convex hull coupled structured surfaces were greatly improved as compared with convex hull and smooth surface. Bionic Type 3 was found to have the best anti-abrasive wear property: the abrasion loss was 11.5 mg. The wear morphology was observed by a scanning electron microscope. Smooth surface was characterized with wide, large size of grinding debris, while the bionic non-smooth surface featured narrow and small size abrasive dust. The results obtained from EDEM simulation agreed well with those of the aforementioned real scenario tests. It was revealed that the wear areas of the micro-thorn and convex hull coupled structured surface were mainly concentrated on the edge of convex hull and micro-thorn that faced the coming direction of particle flow. The geometric structure of the convex hull had beneficial effects on changing the movement behavior of particles, which means the stream of particle flow could be altered from a sliding to rolling state. Consequently, the ploughing and cutting phenomena of particles that act on the surfaces were greatly mitigated. Moreover, after being coupled with micro-thorns, the anti-abrasive wear preparty of the bionic convex hull geometrical structured surface was further improved. The rebound angle of particle flow that contacted the bionic micro-thorn coupled convex hull structured surface was greater than that of the conventional convex hull surface. Therefore, the dispersion effect of particle flow was further enhanced, since the movement behavior of the subsequent impact particle flow was altered. As a result, the wear of the bionic non-smooth surface was further reduced. This biconically inspired novel micro-thorn and convex hull coupled structured surface could provide theatrical and technical references to enhance the wear resistance performance of the soil-engaging component of agricultural machinery and mitigate the problem of abrasive wear failure.
35
Koziel, Slawomir, and Adrian Bekasiewicz. "Simulation-driven design of compact ultra-wideband antenna structures." Engineering Computations 33, no. 4 (June 13, 2016): 1051–69. http://dx.doi.org/10.1108/ec-06-2015-0163.
Анотація:
Purpose – The purpose of this paper is to investigate strategies and algorithms for expedited design optimization and explicit size reduction of compact ultra-wideband (UWB) antennas. Design/methodology/approach – Formulation of the compact antenna design problem aiming at explicit size reduction while maintaining acceptable electrical performance is presented. Algorithmic frameworks are described suitable for handling various design situations and involving simulation models without and with response gradients available. Numerical and experimental case studies are provided demonstrating feasibility of solving real-world miniaturized antenna design tasks. Findings – It is possible, through appropriate combination of the global and local optimization methods, surrogate modeling techniques and response correction methods, to find optimum dimensions of antenna structures that minimize antenna size while maintaining acceptable electrical performance. Design optimization can be performed at practically feasible computational costs. Research limitations/implications – The study summarizes recent advances in miniaturization-oriented design optimization of UWB antennas. The presented techniques reach far beyond the commonly used design approaches based on parameter sweeps and similar hands-on methods, particularly in terms of automation, reliability, and reduction of the computational costs of the design processes. Originality/value – The proposed design problem formulation and algorithmic frameworks proved useful for rapid design of compact UWB antenna structures, which is extremely challenging when using conventional methods. To the knowledge, this is the first attempt to efficient solving of this type of design problems, especially in the context of explicit antenna size reduction.
36
Beltz, G. E., M. Chang, J. S. Speck, W. Pompe, and A. E. Romanov. "Computer simulation of threading dislocation density reduction in heteroepitaxial layers." Philosophical Magazine A 76, no. 4 (October 1997): 807–35. http://dx.doi.org/10.1080/01418619708214212.
37
Kano, Junya, Hiroshi Mio, Fumio Saito, and Mitsuo Tanjo. "Estimation of Size Reduction Rate of Gibbsite in Tumbling Mills with Different Diameters by Computer Simulation." JOURNAL OF CHEMICAL ENGINEERING OF JAPAN 32, no. 6 (1999): 747–51. http://dx.doi.org/10.1252/jcej.32.747.
38
Nader, François, Patrick Pizette, Nicolin Govender, Daniel N. Wilke, and Jean-François Ferellec. "Modelling realistic ballast shape to study the lateral pull behaviour using GPU computing." EPJ Web of Conferences 249 (2021): 06003. http://dx.doi.org/10.1051/epjconf/202124906003.
Анотація:
The use of the Discrete Element Method to model engineering structures implementing granular materials has proven to be an efficient method to response under various behaviour conditions. However, the computational cost of the simulations increases rapidly, as the number of particles and particle shape complexity increases. An affordable solution to render problems computationally tractable is to use graphical processing units (GPU) for computing. Modern GPUs offer up 10496 compute cores, which allows for a greater parallelisation relative to 32-cores offered by high-end Central Processing Unit (CPU) compute. This study outlines the application of BlazeDEM-GPU, using an RTX 2080Ti GPU (4352 cores), to investigate the influence of the modelling of particle shape on the lateral pull behaviour of granular ballast systems used in railway applications. The idea is to validate the model and show the benefits of simulating non-spherical shapes in future large-scale tests. The algorithm, created to generate the shape of the ballast based on real grain scans, and using polyhedral shape approximations of varying degrees of complexity is shown. The particle size is modelled to scale. A preliminary investigation of the effect of the grain shape is conducted, where a sleeper lateral pull test is carried out in a spherical grains sample, and a cubic grains sample. Preliminary results show that elementary polyhedral shape representations (cubic) recreate some of the characteristic responses in the lateral pull test, such as stick/slip phenomena and force chain distributions, which looks promising for future works on railway simulations. These responses that cannot be recreated with simple spherical grains, unless heuristics are added, which requires additional calibration and approximations. The significant reduction in time when using non-spherical grains also implies that larger granular systems can be investigated.
39
Casulleras, J., and E. Guardia. "Computer Simulation of Liquid Methanol II. System Size Effects." Molecular Simulation 8, no. 3-5 (January 1992): 273–83. http://dx.doi.org/10.1080/08927029208022482.
40
Powroźnik, Piotr, Robert Szulim, Wiesław Miczulski, and Krzysztof Piotrowski. "Household Energy Management." Applied Sciences 11, no. 4 (February 11, 2021): 1626. http://dx.doi.org/10.3390/app11041626.
Анотація:
Ensuring flexibility and security in power systems requires the use of appropriate management measures on the demand side. The article presents the results of work related to energy management in households in which renewable energy sources (RES) can be installed. The main part of the article is about the developed elastic energy management algorithm (EEM), consisting of two algorithms, EEM1 and EEM2. The EEM1 algorithm is activated in time periods with a higher energy price. Its purpose is to reduce the power consumed by the appliances to the level defined by the consumer. In contrast, the EEM2 algorithm is run by the Distribution System Operator (DSO) when peak demand occurs. Its purpose is to reduce the power of appliances in a specified time period to the level defined by the DSO. The optimization tasks in both algorithms are based on the Greedy Randomized Adaptive Search Procedure (GRASP) metaheuristic algorithm. The EEM1 and EEM2 algorithms also provide energy consumer comfort. For this purpose, both algorithms take into account the smart appliance parameters proposed in the article: sections of the working devices, power reduction levels, priorities and enablingof time shifting devices. The EEM algorithm in its operation also takes into account the information about the production of power, e.g., generated by the photovoltaic systems. On this basis, it makes decisions on the control of smart appliances. The EEM algorithm also enables inverter control to limit the power transferred from the photovoltaic system to the energy system. Such action is taken on the basis of the DSO request containing the information on the power limits. Such a structure of EEM enables the balancing of energy demand and supply. The possibility of peak demand phenomenon will be reduced. The simulation and experiment results presented in the paper confirmed the rationality and effectiveness of the EEM algorithm.
41
Alexandrov, I. V., and N. A. Enikeev. "X-ray analysis and computer simulation for grain size determination in nanostructured materials." Materials Science and Engineering: A 286, no. 1 (June 2000): 110–14. http://dx.doi.org/10.1016/s0921-5093(00)00652-3.
42
Turichin, Gleb A., Ekaterina A. Valdaytseva, Stanislav L. Stankevich, and Ilya N. Udin. "Computer Simulation of Hydrodynamic and Thermal Processes in DLD Technology." Materials 14, no. 15 (July 25, 2021): 4141. http://dx.doi.org/10.3390/ma14154141.
Анотація:
This article deals with the theoretical issues of the formation of a melt pool during the process of direct laser deposition. The shape and size of the pool depends on many parameters, such as the speed and power of the process, the optical and physical properties of the material, and the powder consumption. On the other hand, the influence of the physical processes occurring in the material on one another is significant: for instance, the heating of the powder and the substrate by laser radiation, or the formation of the free surface of the melt, taking into account the Marangoni effect. This paper proposes a model for determining the size of the melt bath, developed in a one-dimensional approximation of the boundary layer flow. The dimensions and profile of the surface and bottom of the melt pool are obtained by solving the problem of convective heat transfer. The influence of the residual temperature from the previous track, as well as the heat from the heated powder of the gas–powder jet, taking into account its spatial distribution, is considered. The simulation of the size and shape of the melt pool, as well as its free surface profile for different alloys, is performed with 316 L steel, Inconel 718 nickel alloy, and VT6 titanium alloy
43
Adanuvor, P. K., R. E. White, and A. J. Appleby. "A Computer Simulation of the Oxygen Reduction Reaction in Carbonate Melts." Journal of The Electrochemical Society 137, no. 7 (July 1, 1990): 2095–103. http://dx.doi.org/10.1149/1.2086891.
44
Shill, Pintu Chandra, M. A. H. Akhand, MD Asaduzzaman, and Kazuyuki Murase. "Optimization of Fuzzy Logic Controllers with Rule Base Size Reduction using Genetic Algorithms." International Journal of Information Technology & Decision Making 14, no. 05 (September 2015): 1063–92. http://dx.doi.org/10.1142/s0219622015500273.
Анотація:
In this paper, we present the automatic design methods with rule base size reduction for fuzzy logic controllers (FLCs) through real and binary coded coupled genetic algorithms (GAs). The adaptive schema is divided into two phases: the first phase is concerned with optimizing the FLCs membership functions and second phase called rule learning and reducing phase which automatically generates the fuzzy rules as well as determines the minimum number of rules required for building the fuzzy models. In the second phase, the redundant rules are removed by setting their all consequent weight factor to zero and merging the conflicting rules during the learning process. The first and second phases are carried out by the real and binary coded coupled GAs, respectively. Optimizing the MFs with learning and reducing rule base concurrently represents a way to maximize the performance of a FLC. The control algorithm is successfully tested for intelligent control of two degrees of freedom inverted pendulum. Finally, the simulation studies exhibits the better or competitive performance of the proposed method when compared with the existing methods.
45
Aguero, Stephanie, and Raphaël Terreux. "Degradation of High Energy Materials Using Biological Reduction: A Rational Way to Reach Bioremediation." International Journal of Molecular Sciences 20, no. 22 (November 7, 2019): 5556. http://dx.doi.org/10.3390/ijms20225556.
Анотація:
Explosives molecules have been widely used since World War II, leading to considerable contamination of soil and groundwater. Recently, bioremediation has emerged as an environmentally friendly approach to solve such contamination issues. However, the 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) explosive, which has very low solubility in water, does not provide satisfying results with this approach. In this study, we used a rational design strategy for improving the specificity of the nitroreductase from E. Cloacae (PDB ID 5J8G) toward HMX. We used the Coupled Moves algorithm from Rosetta to redesign the active site around HMX. Molecular Dynamics (MD) simulations and affinity calculations allowed us to study the newly designed protein. Five mutations were performed. The designed nitroreductase has a better fit with HMX. We observed more H-bonds, which productively stabilized the HMX molecule for the mutant than for the wild type enzyme. Thus, HMX’s nitro groups are close enough to the reductive cofactor to enable a hydride transfer. Also, the HMX affinity for the designed enzyme is better than for the wild type. These results are encouraging. However, the total reduction reaction implies numerous HMX derivatives, and each of them has to be tested to check how far the reaction can’ go.
46
Chen, I.-Wei, Gregory N. Hassold, and David J. Srolovitz. "Computer Simulation of Final-Stage Sintering: II, Influence of Initial Pore Size." Journal of the American Ceramic Society 73, no. 10 (October 1990): 2865–72. http://dx.doi.org/10.1111/j.1151-2916.1990.tb06687.x.
47
Pietrenko-Dabrowska, Anna, and Slawomir Koziel. "Cost-Efficient EM-Driven Size Reduction of Antenna Structures by Multi-Fidelity Simulation Models." Electronics 10, no. 13 (June 24, 2021): 1536. http://dx.doi.org/10.3390/electronics10131536.
Анотація:
Design of antenna systems for emerging application areas such as the Internet of Things (IoT), fifth generation wireless communications (5G), or remote sensing, is a challenging endeavor. In addition to meeting stringent performance specifications concerning electrical and field properties, the structure has to maintain small physical dimensions. The latter normally requires searching for trade-off solutions because miniaturization has detrimental effects on antenna characteristics, including the impedance matching, gain, efficiency, or axial ratio bandwidth. Furthermore, explicit size reduction is more demanding than optimization with respect to other figures of merit. On the one hand, it is a constrained task with acceptance thresholds set on the bandwidth, gain, etc. On the other hand, optimum solutions are normally located at the boundary of the feasible region, traversing of which is a difficult problem by itself. The necessity of using full-wave electromagnetic (EM) analysis for antenna evaluation only aggravates the problem due to high computational costs associated with numerical optimization algorithms. This paper proposes a procedure for expedited optimization-based miniaturization of antenna structures involving trust-region gradient search and multi-fidelity EM simulations, as well as implicit handling of design constraints using a penalty function approach. The assumed model management scheme is associated with the convergence status of the optimization process with the lowest fidelity model employed at the early stages of the algorithm run and the discretization density of the structure gradually increased to reach the high-fidelity level towards the end of the run. This allows us to achieve a considerable computational speedup without compromising the reliability. Our methodology is demonstrated using two broadband microstrip antennas. The obtained CPU savings exceed seventy percent as compared to the reference procedure involving high-fidelity model only.
48
Yoxall, A., J. Luxmoore, J. Rowson, J. Langley, and R. Janson. "Size does matter: further studies in hand–pack interaction using computer simulation." Packaging Technology and Science 21, no. 2 (2008): 61–72. http://dx.doi.org/10.1002/pts.778.
49
Nikolic, Zoran. "Three-dimensional computer simulation of grain coarsening during sintering." Science of Sintering 44, no. 1 (2012): 3–15. http://dx.doi.org/10.2298/sos1201003n.
Анотація:
This paper presents a computational study of the three-dimensional computer simulation of grain coarsening using a sintering model based on sintering law (a rate law of inter-grain distance reduction) describing the evolution of neck geometry.
50
Lannoo, Michel. "Atomistic Nanodevice Simulation." Solid State Phenomena 108-109 (December 2005): 787–88. http://dx.doi.org/10.4028/www.scientific.net/ssp.108-109.787.
Анотація:
There now a large variety of methods exists for the elaboration of nanoobjects and nanodevices. At the same time the reduction in size together with the improvement of theoretical techniques and computational power should allow efficient quantitative simulation of these objects. Such predictive simulation is highly needed since it can serve as a useful guide to build new nanostructures with the desired properties. The aim of this talk is than to give an overview of what has already been achieved in this rapidly evolving field, what can be done at present and what is expected for the future. The focus will be mostly on semiconductor nanostructures and especially silicon.