Journal articles on the topic 'One-dimensional refined model'
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Carrera, E., and M. Filippi. "A refined one-dimensional rotordynamics model with three-dimensional capabilities." Journal of Sound and Vibration 366 (March 2016): 343–56. http://dx.doi.org/10.1016/j.jsv.2015.12.036.
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Pereira, Wildrimak S., Jhonatan M. S. Costa, Fábio L. C. Costa Júnior, Rômulo O. Barros, and Ricardo M. Ramos. "Glucosamine-6-Phosphate Synthase de Mycobacterium tuberculosis um estudo in silico para predição de um modelo tridimensional refinado." Somma: Revista Cientifica do Instituto Federal de Educação, Ciência e Tecnologia do Piauí 7, no. 1 (April 21, 2021): 1–9. http://dx.doi.org/10.51361/somma.v7i1.49.
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Tuberculosis is one of the main causes of death by an infectious agent in the world, according to the World Health Organization. Studies indicate that enzymes involved in the biosynthesis of uridine diphospho-N-acetylglucosamine are essential for the life cycle of the bacterium. One of these enzymes is glucosamine-6-phosphate synthase (GlmS), which does not have a three-dimensional structure available in the protein database on the internet. In this work, structural bioinformatics methods (comparative modeling and molecular refinement) were used to build a refined three-dimensional model for the GlmS enzyme of Mycobacterium tuberculosis. The model was generated using four templates structures (crystallographic). The results obtained for the stereochemical and general parameters of the refined model were better than the original model and similarto those templates structures, validating the refined model.
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MARTIN, PH A., and G. NENCIU. "SEMI-CLASSICAL INELASTIC S-MATRIX FOR ONE-DIMENSIONAL N-STATES SYSTEMS." Reviews in Mathematical Physics 07, no. 02 (February 1995): 193–242. http://dx.doi.org/10.1142/s0129055x95000116.
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A mathematically fully controlled study of the semi-classical S-matrix associated with one-dimensional N-states systems is presented for energies above the barriers. The transmission coefficients are described by an “effective evolution” model which at high energies approaches the usual “common trajectory” model. In the two-states case a refined Landau-Zener formula describing the cross-over regime between avoided and real crossings is obtained.
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Zappino, Enrico, and Erasmo Carrera. "Thermo-piezo-elastic analysis of amplified piezoceramic actuators using a refined one-dimensional model." Journal of Intelligent Material Systems and Structures 29, no. 17 (August 3, 2017): 3482–94. http://dx.doi.org/10.1177/1045389x17721026.
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The thermo-piezo-elastic analysis of amplified piezoceramic actuators is presented in this article. A refined one-dimensional multi-field finite element model, based on the Carrera Unified Formulation, has been developed. Thermal and piezoelectric effects have been included in the structural model and a fully coupled thermo-piezo-elastic analysis has been performed. The finite element model has been assessed by comparing it with results from open literature The model has also been used to perform the analysis of complex amplified piezoceramic actuators. These actuators are able to amplify the displacements produced by piezoceramic material, but they suffer from high deformations when they undergo high thermal loads. An accurate thermal analysis has been performed to evaluate the strain/stress field. The results show the accuracy of the present model and its capabilities in multi-field analyses.
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Liao, Sheng-hui, Xing-hao Zhu, Jing Xie, Vikesh Kumar Sohodeb, and Xi Ding. "Influence of Trabecular Bone on Peri-Implant Stress and Strain Based on Micro-CT Finite Element Modeling of Beagle Dog." BioMed Research International 2016 (2016): 1–11. http://dx.doi.org/10.1155/2016/3926941.
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The objective of this investigation is to analyze the influence of trabecular microstructure modeling on the biomechanical distribution of the implant-bone interface. Two three-dimensional finite element mandible models, one with trabecular microstructure (a refined model) and one with macrostructure (a simplified model), were built. The values of equivalent stress at the implant-bone interface in the refined model increased compared with those of the simplified model and strain on the contrary. The distributions of stress and strain were more uniform in the refined model of trabecular microstructure, in which stress and strain were mainly concentrated in trabecular bone. It was concluded that simulation of trabecular bone microstructure had a significant effect on the distribution of stress and strain at the implant-bone interface. These results suggest that trabecular structures could disperse stress and strain and serve as load buffers.
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Mackney, Michael D. A., and Carl T. F. Ross. "Preliminary Ship Design Using One and Two-Dimensional Models." Marine Technology and SNAME News 36, no. 02 (April 1, 1999): 102–12. http://dx.doi.org/10.5957/mt1.1999.36.2.102.
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Computational studies of hull-superstructure interaction were carried out using one-, two-and three-dimensional finite element analyses. Simplification of the original three-dimensional cases to one- and two-dimensional ones was undertaken to reduce the data preparation and computer solution times in an extensive parametric study. Both the one- and two-dimensional models were evaluated from numerical and experimental studies of the three-dimensional arrangements of hull and superstructure. One-dimensional analysis used a simple beam finite element with appropriately changed sections properties at stations where superstructures existed. Two-dimensional analysis used a four node, first order quadrilateral, isoparametric plane elasticity finite element, with a corresponding increase in the grid domain where the superstructure existed. Changes in the thickness property reflected deck stiffness. This model was essentially a multi-flanged beam with the shear webs representing the hull and superstructure sides, and the flanges representing the decks One-dimensional models consistently and uniformly underestimated the three-dimensional behaviour, but were fast to create and run. Two-dimensional models were also consistent in their assessment, and considerably closer in predicting the actual behaviours. These models took longer to create than the one-dimensional, but ran in very much less time than the refined three-dimensional finite element models Parametric insights were accomplished quickly and effectively with the simplest model and processor, but two-dimensional analyses achieved closer absolute measure of the displacement behaviours. Although only static analysis with simple loading and support conditions were presented, it is believed that similar benefits would be found for other loadings and support conditions. Other engineering components and structures may benefit from similarly judged simplification using one- and two-dimensional models to reduce the time and cost of preliminary design.
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Baraldi, Daniele, Claudia Brito De Carvalho Bello, Antonella Cecchi, and Filippo Ubertini. "Refined Rigid Block Model for In-Plane Loaded Masonry." Advances in Civil Engineering 2020 (September 29, 2020): 1–13. http://dx.doi.org/10.1155/2020/8844759.
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In this work, a refined rigid block model is proposed for studying the in-plane behavior of regular masonry. The rigid block model is based on an existing discrete/rigid model with rigid blocks and elastoplastic interfaces that already proven its effectiveness in representing masonry behavior in linear and nonlinear fields. In this case, the proposed model is improved by assuming rigid quadrilateral elements connected by one-dimensional nonlinear interfaces, which are adopted both to represent mortar (or dry) joints between the blocks and also to represent inner potential cracks into the blocks. Furthermore, the softening behavior of interfaces in tension and shear is taken into account. Several numerical tests are performed by considering masonry panels with regular texture subjected to compression and shear. Particular attention is given to the collapse mechanisms and the pushover curves obtained numerically and compared with existing numerical and laboratory results. Furthermore, the numerical tests aim to evaluate the applicability limits of the proposed model with respect to existing results.
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Bhalla, Suresh, and Sumedha Moharana. "A refined shear lag model for adhesively bonded piezo-impedance transducers." Journal of Intelligent Material Systems and Structures 24, no. 1 (September 5, 2012): 33–48. http://dx.doi.org/10.1177/1045389x12457837.
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The performance (sensing/actuating) of a piezotransducer highly depends upon the ability of the bond layer to transfer the stress and strain (through shear lag mechanism) between the transducer and the structure. Therefore, the coupled electromechanical response of the piezotransducer should consider the effect of dynamic behaviour, geometry and composition of the adhesive layer used to bond the transducer patch on the structure. This article presents a new refined analytical model for inclusion of the shear lag effect in modelling of adhesively bonded piezoelectric ceramic (lead zirconate titanate) patches for consideration in the electromechanical impedance technique. The previous models neglected the inertial term in shear lag formulations for simplicity. The present refined model, on the other hand, considers the inertial and the shear lag effects simultaneously, and is therefore more rigorous and complete. In this article, the formulations are first derived for one-dimensional case, and then extended to two-dimensional lead zirconate titanate–structure interaction. The overall results are found to be in better proximity to experimental observations. The refined formulations are employed for a detailed stress analysis of the bond layer. The article concludes with a parametric study on the influence of various sensor parameters on the electromechanical impedance signatures.
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Anile, A. M., O. Muscato, S. Rinaudo, and P. Vergari. "Testing Hydrodynamical Models on the Characteristics of a One-Dimensional Submicrometer Structure." VLSI Design 6, no. 1-4 (January 1, 1998): 155–60. http://dx.doi.org/10.1155/1998/63185.
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Recent advances in technology leads to increasing high speed performance of submicrometer electron devices by the scaling of both process and geometry. In order to aid the design of these devices it is necessary to utilize powerful numerical simulation tools. In an industrial environment the simulation codes based on the Drift-Diffusion models have been widely used. However the shrinking dimension of the devices causes the Drift-Diffusion based simulators to become less accurate. Then it is necessary to utilize more refined models (including higher order moments of the distribution function) in order to correctly predict the behaviour of these devices. Several hydrodynamical models have been considered as viable simulation tools. It is possible to discriminate among the several hydrodynamical models on the basis of their results on the output characteristics of the electron device which are measurable (I-V curves). We have analyzed two classes of hydrodynamical models: i) HFIELDS hydrodynamical models and HFIELDS drift-diffusion model; ii) self-consistent extended hydrodynamical models with relaxation times determined from Monte Carlo simulations.
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Usuba, Hiroki, Shota Yamanaka, and Homei Miyashita. "Modeling Movement Times and Success Rates for Acquisition of One-dimensional Targets with Uncertain Touchable Sizes." Proceedings of the ACM on Human-Computer Interaction 5, ISS (November 3, 2021): 1–15. http://dx.doi.org/10.1145/3486953.
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In touch interfaces, a target, such as an icon, has two widths: the visual width and the touchable width. The visual width is the target's appearance, and the touchable width is the area in which users can touch a target and execute an action. In this study, we conduct two experiments to investigate the effects of the visual and touchable widths on touch pointing performance (movement time and success rate). Based on the results, we build candidate models for predicting the movement time and compare them by the values of adjusted R^2 and AIC. In addition, we build a success rate model and test it through cross-validation. Existing models can be applied only to situations where the visual and touchable widths are equal, and we show that our refined model achieves better model fitness, even when such widths are different. We also discuss the design implications of the touch interfaces based on our models.
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Bighamian, Ramin, Jin-Oh Hahn, George Kramer, and Christopher Scully. "Accuracy assessment methods for physiological model selection toward evaluation of closed-loop controlled medical devices." PLOS ONE 16, no. 4 (April 30, 2021): e0251001. http://dx.doi.org/10.1371/journal.pone.0251001.
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Physiological closed-loop controlled (PCLC) medical devices are complex systems integrating one or more medical devices with a patient’s physiology through closed-loop control algorithms; introducing many failure modes and parameters that impact performance. These control algorithms should be tested through safety and efficacy trials to compare their performance to the standard of care and determine whether there is sufficient evidence of safety for their use in real care setting. With this aim, credible mathematical models have been constructed and used throughout the development and evaluation phases of a PCLC medical device to support the engineering design and improve safety aspects. Uncertainties about the fidelity of these models and ambiguities about the choice of measures for modeling performance need to be addressed before a reliable PCLC evaluation can be achieved. This research develops tools for evaluating the accuracy of physiological models and establishes fundamental measures for predictive capability assessment across different physiological models. As a case study, we built a refined physiological model of blood volume (BV) response by expanding an original model we developed in our prior work. Using experimental data collected from 16 sheep undergoing hemorrhage and fluid resuscitation, first, we compared the calibration performance of the two candidate physiological models, i.e., original and refined, using root-mean-squared error (RMSE), Akiake information criterion (AIC), and a new multi-dimensional approach utilizing normalized features extracted from the fitting error. Compared to the original model, the refined model demonstrated a significant improvement in calibration performance in terms of RMSE (9%, P = 0.03) and multi-dimensional measure (48%, P = 0.02), while a comparable AIC between the two models verified that the enhanced calibration performance in the refined model is not due to data over-fitting. Second, we compared the physiological predictive capability of the two models under three different scenarios: prediction of subject-specific steady-state BV response, subject-specific transient BV response to hemorrhage perturbation, and leave-one-out inter-subject BV response. Results indicated enhanced accuracy and predictive capability for the refined physiological model with significantly larger proportion of measurements that were within the prediction envelope in the transient and leave-one-out prediction scenarios (P < 0.02). All together, this study helps to identify and merge new methods for credibility assessment and physiological model selection, leading to a more efficient process for PCLC medical device evaluation.
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Zhavoronok, Sergey I. "ON THE USE OF EXTENDED PLATE THEORIES OF VEKUA – AMOSOV TYPE FOR WAVE DISPERSION PROBLEMS." International Journal for Computational Civil and Structural Engineering 14, no. 1 (March 30, 2018): 36–48. http://dx.doi.org/10.22337/2587-9618-2018-14-1-36-48.
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he extended plate theory of I.N. Vekua – A.A. Amosov type is constructed on the background of the dimensional reduction approach and the Lagrangian variational formalism of analytical dynamics. The proposed theory allows one to obtain the hierarchy of refined plate models of different orders and to satisfy the boundary conditions on plates’ faces exactly by introducing the corresponding constraint equations into the Lagrangian model of two-dimensional continuum. The normal wave dispersion in an elastic layer is considered, the convergence of the two-dimensional solutions to the exact one is studied for the locking phase frequencies, the dimensionless stress distributions across the thickness of a layer are shown.
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Vázquez-Prada, M., Á. González, J. B. Gómez, and A. F. Pacheco. "Forecasting characteristic earthquakes in a minimalist model." Nonlinear Processes in Geophysics 10, no. 6 (December 31, 2003): 565–71. http://dx.doi.org/10.5194/npg-10-565-2003.
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Abstract. Using error diagrams, we quantify the forecasting of characteristic-earthquake occurrence in a recently introduced minimalist model. Initially we connect the earthquake alarm at a fixed time after the ocurrence of a characteristic event. The evaluation of this strategy leads to a one-dimensional numerical exploration of the loss function. This first strategy is then refined by considering a classification of the seismic cycles of the model according to the presence, or not, of some factors related to the seismicity observed in the cycle. These factors, statistically speaking, enlarge or shorten the length of the cycles. The independent evaluation of the impact of these factors in the forecast process leads to two-dimensional numerical explorations. Finally, and as a third gradual step in the process of refinement, we combine these factors leading to a three-dimensional exploration. The final improvement in the loss function is about 8.5%.
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Ahn, Hyunjin, Junhyeok Byeon, Seung-Yeal Ha, and Jaeyoung Yoon. "On the relativistic flocks over the unit sphere and the hyperboloid in a bonding force field." Journal of Mathematical Physics 64, no. 1 (January 1, 2023): 012705. http://dx.doi.org/10.1063/5.0108837.
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We study emergent collective dynamics for the relativistic Cucker–Smale (RCS) model in a bonding force field on an abstract Riemannian manifold. The abstract RCS model in a bonding force field contains forcing terms involved with geometric quantities, such as parallel transport, Riemannian metric tensor, and logarithm mapping on manifolds. We consider two explicit realizations of the RCS model on the Euclidean unit sphere and the hyperboloid and present refined emergent dynamics of the explicit RCS models and asymptotic behaviors. We also show that the explicit RCS models reduce to the relativistic Kuramoto-type models with a memory effect for a one-dimensional setting.
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SU, YA, and XINBO GAO. "ITERATIVE SHAPE REFINEMENT IN AAM." International Journal of Image and Graphics 11, no. 01 (January 2011): 137–51. http://dx.doi.org/10.1142/s0219467811004032.
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Active appearance model (AAM) is a powerful model to describe deformable objects in terms of shape and texture. It models the shape and the texture variations linearly and independently and has been widely applied to pattern recognition. However, there are two problems in the model building procedure. On the one hand, much shape information is lost from the shape model because only the sparse landmarks manually labeled are taken into account. On the other hand, the high-dimensional texture has too much nonlinearity. It is resulted from the structure information left by the shape model. In this paper, we propose a shape refinement framework to account for the problems. Firstly, the texture complexity of the shape model is obtained statistically. Then, the shape model is refined based on the texture complexity. Finally, the texture model is rebuilt based on the texture complexity according to the refined shape model. This is an iterative procedure which gradually improves the shape model and reduces the nonlinear of the texture model. As a result, both the complexity and the computational cost of AAM are reduced. Experimental results show that the proposed method greatly improves the accuracy and efficiency of AAM.
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Zhou, Xijun, Yongjin Ye, Xianyu Zhang, Xiuwei Yang, and Haijun Wang. "Refined 1D–3D Coupling for High-Frequency Forced Vibration Analysis in Hydraulic Systems." Energies 15, no. 16 (August 20, 2022): 6051. http://dx.doi.org/10.3390/en15166051.
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High-Frequency Pressure Fluctuation (HFPF) is an extensively observed hydraulic phenomenon in pumped-storage power stations and water conveyance projects. The investigation of the propagation characteristics of the pressure perturbation is of great significance for the safe operation of hydraulic facilities. In this study, a one-dimensional (1D)–three-dimensional (3D) coupling model is established based on the combination of the Method of Characteristics (MOC) and Computational Fluid Dynamics (CFD) and implanted in the open source software OpenFOAM. The established model in this study implants the dynamic mesh module into the original OpenFOAM solver sonicLiquidFoam and presents the complete solution procedure of the CFD model with the dynamic mesh considered. The vibration of the pipe walls modeled by the mesh motion is employed to numerically generate the HFPF in the hydraulic system, which could not be implemented in the traditional MOC model. The independence of the pressure perturbation in the pipeline system is validated by the time-domain pressure variation. The graphical method is applied to describe the multiple reflection and superposition characteristics of the traveling wave in a simplified hydraulic system. Based on this, the mechanism of the superimposed characteristic of the traveling and standing pressure waves in the hydraulic system are analyzed, and the theoretical superimposed time-domain processes and the variations of the pressure oscillation magnitude are analyzed and presented. The 1D–3D coupling method and the theoretical analysis method could be referenced by other complex hydraulic systems.
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Yu, Wenbin, and Dewey H. Hodges. "Elasticity Solutions Versus Asymptotic Sectional Analysis of Homogeneous, Isotropic, Prismatic Beams." Journal of Applied Mechanics 71, no. 1 (January 1, 2004): 15–23. http://dx.doi.org/10.1115/1.1640367.
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The original three-dimensional elasticity problem of isotropic prismatic beams has been solved analytically by the variational asymptotic method (VAM). The resulting classical model (Euler-Bernoulli-like) is the same as the superposition of elasticity solutions of extension, Saint-Venant torsion, and pure bending in two orthogonal directions. The resulting refined model (Timoshenko-like) is the same as the superposition of elasticity solutions of extension, Saint-Venant torsion, and both bending and transverse shear in two orthogonal directions. The fact that the VAM can reproduce results from the theory of elasticity proves that two-dimensional finite-element-based cross-sectional analyses using the VAM, such as the variational asymptotic beam sectional analysis (VABS), have a solid mathematical foundation. One is thus able to reproduce numerically with VABS the same results for this problem as one obtains from three-dimensional elasticity, but with orders of magnitude less computational cost relative to three-dimensional finite elements.
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Krupp, Anna, Eva Rebecca Barth, Rana Seymen, and Carsten Strohmann. "Crystal structures, Hirshfeld atom refinements and Hirshfeld surface analyses of tris(4,5-dihydrofuran-2-yl)methylsilane and tris(4,5-dihydrofuran-2-yl)phenylsilane." Acta Crystallographica Section E Crystallographic Communications 76, no. 9 (August 28, 2020): 1514–19. http://dx.doi.org/10.1107/s2056989020011470.
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The title compounds, C13H18O3Si (1) and C18H20O3Si (2), represent functionalizable dihydrofuranylsilanes, which permit substitution by a variety of nucleophiles. The crystal structures of 1 and 2 display weak intermolecular C—H...O hydrogen-bonding interactions (quantified by Hirshfeld surface analysis), leading to a two-dimensional supramolecular network for 1 and a one-dimensional supramolecular network for 2. The crystal structures of 1 and 2 were refined both on the basis of the independent atom model (IAM) and the Hirshfeld atom refinement (HAR) approach, and the results are comparatively discussed.
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Onoda, Mitsuko, Anne-Claire Dhaussy, and Yasushi Kanke. "Structural characterization of YV4O8: simultaneous analysis of coexisting polytypes and simulation of diffuse scattering for a stacking disorder model." Acta Crystallographica Section B Structural Science 59, no. 4 (July 25, 2003): 429–38. http://dx.doi.org/10.1107/s0108768103010450.
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The structure of a crystal of newly synthesized YV4O8 was refined on the assumption that two polytypes and their respective twin forms intergrow. The model was expressed as a commensurate composite crystal with two types of subsystem: one is a V4O8 framework with rather large tunnels and the other consists of Y ions. In the tunnels, Y ions and vacancies are located at every second site in an ordered manner that is characteristic of each polytype. Refinement was performed using a high-dimensional formalism and all reflections from all domains. Diffuse streaks observed in the X-ray and electron diffraction patterns were simulated using the matrix method that has been used for one-dimensional disorder such as stacking faults. The unusual diffraction phenomena that occur in a crystal of YV4O8 are explained as arising from a multiple-domain structure of coexisting polytypes.
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Britton, G., T. S. Beng, and Y. Wang. "Virtual concurrent product development of plastic injection moulds." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 214, no. 2 (February 1, 2000): 165–68. http://dx.doi.org/10.1243/0954405001517540.
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This paper describes three approaches for virtual product development of plastic injection moulds. The first is characterized by the use of three-dimensional computer aided design (CAD) for product design, two-dimensional drafting for mould design and three-dimensional computer aided design/manufacture (CAD/CAM) for mould manufacture. The second is characterized by the use of three-dimensional CAD models by all three participants, but between any two participants some form of file conversion is normally required because different CAD systems are used. The first two approaches share one common feature: the models are passed serially from the product designer to the mould designer and on to the toolmaker. They represent current practice in industry. The third approach is a proposed collaborative design process. Participants can work concurrently on the same model, sharing their knowledge and experience. The process is currently being refined and will be validated later this year with a prototype system based on Unigraphics iMAN software.
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Tseng, Wan-Ling, Huang-Hsiung Hsu, Yung-Yao Lan, Wei-Liang Lee, Chia-Ying Tu, Pei-Hsuan Kuo, Ben-Jei Tsuang, and Hsin-Chien Liang. "Improving Madden–Julian oscillation simulation in atmospheric general circulation models by coupling with a one-dimensional snow–ice–thermocline ocean model." Geoscientific Model Development 15, no. 14 (July 20, 2022): 5529–46. http://dx.doi.org/10.5194/gmd-15-5529-2022.
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Abstract. A one-column, turbulent, and kinetic-energy-type ocean mixed-layer model (snow–ice–thermocline, SIT), when coupled with three atmospheric general circulation models (AGCMs), yields superior Madden–Julian oscillation (MJO) simulations. SIT is designed to have fine layers similar to those observed near the ocean surface; therefore, it can realistically simulate the diurnal warm layer and cool skin. This refined discretization of the near-surface ocean in SIT provides accurate sea surface temperature (SST) simulation, and thus facilitates realistic air–sea interaction. Coupling SIT with the European Centre/Hamburg Model version 5, the Community Atmosphere Model version 5, and the High-Resolution Atmospheric Model significantly improved MJO simulation in three coupled AGCMs compared to the AGCM driven by a prescribed SST. This study suggests two major improvements to the coupling process. First, during the preconditioning phase of MJO over the Maritime Continent (MC), the often underestimated surface latent heat bias in AGCMs can be corrected. Second, during the phase of strongest convection over the MC, the change in intraseasonal circulation in the meridional circulation enhancing near-surface moisture convergence is the dominant factor in the coupled simulations relative to the uncoupled experiments. The study results show that a fine vertical resolution near the surface, which better captures temperature variations in the upper few meters of the ocean, considerably improves different models with different configurations and physical parameterization schemes; this could be an essential factor for accurate MJO simulation.
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Song, Weibo. "A New Method for Refined Recognition for Heart Disease Diagnosis Based on Deep Learning." Information 11, no. 12 (November 28, 2020): 556. http://dx.doi.org/10.3390/info11120556.
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The proper evaluation of heart health requires professional medical experience. Therefore, in clinical diagnosis practice, the development direction is to reduce the high dependence of the diagnosis process on medical experience and to more effectively improve the diagnosis efficiency and accuracy. Deep learning has made remarkable achievements in intelligent image analysis technology involved in the medical process. From the aspect of cardiac diagnosis, image analysis can extract more profound and abundant information than sequential electrocardiogram (ECG) signals. Therefore, a new region recognition and diagnosis method model of a two-dimensional ECG (2D-ECG) signal based on an image format is proposed. This method can identify and diagnose each refined waveform in the cardiac conduction cycle reflected in the image format ECG signal, so as to realize the rapid and accurate positioning and visualization of the target recognition area and finally get the analysis results of specific diseases. The test results show that compared with the results obtained by a one-dimensional sequential ECG signal, the proposed model has higher average diagnostic accuracy (98.94%) and can assist doctors in disease diagnosis with better visualization effect.
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Guilbault, Raynald. "Tooth Influence on Flexural and Torsional Flexibility, and Model Tooth Number Prediction for Optimum Dynamic Simulation of Wide-Faced Spur Gears." Journal of Mechanical Design 128, no. 3 (August 4, 2005): 626–33. http://dx.doi.org/10.1115/1.2180808.
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Refined dynamic analyses of gear pairs, including precise tooth contact description, often lead to unreasonable simulation requirements. Therefore, numerous models employ simplifications, such as two-dimensional deflection of the engaged gear set, which is inappropriate for wide-faced wheels. Other models propose three-dimensional (3D) representation of one tooth on a complete hub. This approach introduces the torsional and flexural deflection of the gear body, but underestimates the corresponding stiffness. Since forthcoming improvements of gear analysis should offer efficient 3D dynamic simulation of wide-faced gear sets, this paper primarily quantifies the flexibility error levels implied with 3D one tooth full hub spur gear models. Subsequently, a procedure is developed to determine the number of teeth required for a 3D model so that it will include the torsional and flexural flexibility of the spur gear body, within acceptable error levels. This procedure offers an efficient approach to optimize the (precision)/(simulation time) ratio. The method deals with gears of any diametral pitch, and covers the common face width and tooth number ranges.
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VOINOV, OLEG V. "Motion stability of a periodic system of bubbles in a liquid." Journal of Fluid Mechanics 438 (July 5, 2001): 247–75. http://dx.doi.org/10.1017/s0022112001004347.
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Wave-like motion in a periodic structure of bubbles that steadily moves through ideal incompressible liquid is considered. The wavelength is microscopically short. Some general local properties containing general information about two-phase flow are found. The dynamics of small-amplitude disturbances is studied in linear systems (called trains) and in spatial structures (such as a cubic lattice). The behaviour of one-dimensional waves in various structures is shown to differ widely: one-dimensional waves in the train do not magnify, whereas in the three-dimensional structure there may be stability and instability of one-dimensional waves. In the continuum limit the one-dimensional instability is demonstrated not to be related to the mean parameters of two-phase flow. The long-wave dynamics is shown to depend significantly on the relative velocity vector orientation in the lattice, but orientation is not included in the usual equations for the two-phase continuum. One result of this study is the relation between the short-wave-type instability of the periodic structure, on the one hand, and the instability of one-dimensional flow of inviscid bubbly liquid discovered by van Wijngaarden on the other. Long microscopic waves are analysed to determine the coefficients of one-dimensional equations for a two-phase continuum model. The velocity orientation at which the coefficients of the traditional one-dimensional model are obtained is found. Short waves in a stationary structure are studied by using the system of equations based on the equation of motion of a small sphere in a general potential flow. A refined equation for the force applied on a sphere in a non-uniform potential flow is derived.
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BRISCHETTO, S., and E. CARRERA. "THERMOMECHANICAL EFFECT IN VIBRATION ANALYSIS OF ONE-LAYERED AND TWO-LAYERED PLATES." International Journal of Applied Mechanics 03, no. 01 (March 2011): 161–85. http://dx.doi.org/10.1142/s1758825111000920.
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The free vibration problem of one-layered and two-layered metallic plates is investigated in this work. The thermomechanical effect is evaluated using a fully coupled thermomechanical model. The free frequency values of fully coupled problems are compared to the values of the pure mechanical problems. In pure mechanical models, the displacement is the only primary variable of the problem, while in fully coupled thermomechanical models, the temperature is also considered as a primary variable and the effect of the thermomechanical stiffness is evaluated. The thermoelastic coupling usually provides higher frequencies with respect to the pure mechanical case because it acts like a thermal source, which is proportional to the strain rate, which leads to a bigger global stiffness of the structure. Both thermomechanical and mechanical models are developed in the framework of Carrera's Unified Formulation (CUF). CUF permits several refined two-dimensional theories to be obtained with orders of expansion in the thickness direction, from linear to fourth-order, for both displacements and temperature. Both equivalent single layer and layer-wise approaches are considered for the multilayered plates. The thermomechanical effect is investigated, in terms of frequencies, for thick and thin one-layered and two-layered plates, and for lower and higher modes. It has mainly been concluded that the thermomechanical coupling: (a) Is correctly determined if both the thermal and mechanical parts are correctly approximated; (b) Is small for each investigated case; (c) Influences the various vibration modes in different ways; and (d) Has a limited dependence on the considered case, but this dependence vanishes if a global coupling is considered. Only fully coupled thermomechanical models allow to analyze this type of problem. The effect of the thermomechanical coupling on higher-order modes can only be investigated using refined two-dimensional theories.
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Wang, Yingxu, Jason Huang, and Jingsheng Lei. "The Formal Design Models of a Universal Array (UA) and its Implementation." International Journal of Software Science and Computational Intelligence 3, no. 3 (July 2011): 69–89. http://dx.doi.org/10.4018/ijssci.2011070106.
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Arrays are one of the most fundamental and widely applied data structures, which are useful for modeling both logical designs and physical implementations of multi-dimensional data objects sharing the same type of homogeneous elements. However, there is a lack of a formal model of the universal array based on it any array instance can be derived. This paper studies the fundamental properties of Universal Array (UA) and presents a comprehensive design pattern. A denotational mathematics, Real-Time Process Algebra (RTPA), allows both architectural and behavioral models of UA to be rigorously designed and refined in a top-down approach. The conceptual model of UA is rigorously described by tuple- and matrix-based mathematical models. The architectural models of UA are created using RTPA architectural modeling methodologies known as the Unified Data Models (UDMs). The physical model of UA is implemented using linear list that is indexed by an offset pointer of elements. The behavioral models of UA are specified and refined by a set of Unified Process Models (UPMs). As a case study, the formal UA models are implemented in Java. This work has been applied in a number of real-time and nonreal-time systems such as compilers, a file management system, the real-time operating system (RTOS+), and the ADT library for an RTPA-based automatic code generation tool.
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Ferjani, Hela, and Habib Boughzala. "New Quasi-One-Dimensional Organic-Inorganic Hybrid Material: 1,3-Bis(4-piperidinium)propane Pentachlorobismuthate(III) Synthesis, Crystal Structure, and Spectroscopic Studies." Journal of Materials 2014 (June 2, 2014): 1–8. http://dx.doi.org/10.1155/2014/253602.
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The organic-inorganic hybrid compound (C13H28N2) BiCl5 was synthesized by solvothermal method. The crystal structure was solved by single-crystal X-ray diffraction. The compound crystallizes in the orthorhombic system space group Cmc21 with a=15.826(4) Å, b=18.746(6) Å, c=7.470(3) Å, and Z=4. The crystal structure was refined down to R=0.019. It consists of corrugated layers of [BiCl5]2− chains, separated by organic [H2TMDP]2+ cations (TMDP=1,3-Bis(4-piperidyl)propane = C13H26N2). The crystal cohesion is achieved by hydrogen bonds N–H⋯Cl joining the organic and inorganic layers. The influence of the organic cations' flexibility is discussed. Raman and infrared spectra of the title compound were recorded in the range of 50–400 and 400–4000 cm−1, respectively. Semiempirical parameter model three (PM3) method has been performed to derive the calculated IR spectrum. The crystal shape morphology was simulated using the Bravais-Friedel and Donnay-Harker model.
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Anosov, A. A. "One-Dimensional Inverse Problem of Passive Acoustic Thermometry Using the Heat Conductivity Equation: Computer and Physical Simulation." Acoustical Physics 68, no. 5 (October 2022): 513–20. http://dx.doi.org/10.1134/s1063771022050049.
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AbstractAn algorithm for reconstructing the time-varying one-dimensional distribution of the deep temperature of the human body under local heating is proposed and experimentally tested on a model. The algorithm requires that the temperature obey the heat conduction equation, the integration of which with a weight that takes into account absorption in the object, makes it possible to obtain the time dependence of the acoustic brightness temperature (measured signal), which in turn is determined by the parameters of the equation. The desired temperature is obtained by solving the heat conduction equation with the found parameters. The algorithm reconstructs two parameters: blood flow and the amplitude of the heating source, which are not determined each time anew, but only refined. In this case, the integration time increases, but the temporal resolution does not suffer: new results can be obtained after any period of time. After 2 min of heating, it is possible to reconstruct the temperature and size of the heated region with an accuracy acceptable for medical applications: 0.5°C and 0.5 mm, respectively.
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Yankovskii, A. P. "The Refined Model of Viscoelastic-Plastic Deformation of Reinforced Cylindrical Shells." PNRPU Mechanics Bulletin, no. 1 (December 15, 2020): 138–49. http://dx.doi.org/10.15593/perm.mech/2020.1.11.
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The paper formulates the initial-boundary-value problem of the viscoelastic-plastic bending behavior of cylindrical circular shells cross-reinforced along equidistant surfaces. The instant elastoplastic deformation of the shell composition components is described by the governing equations of the theory of plastic flow with isotropic hardening. The viscoelastic deformation of these materials is described by the defining relations of the Maxwell - Boltzmann model of body. The geometric nonlinearity of the problem is taken into account in the Karman approximation. The used system of two-dimensional resolving equations and the corresponding initial and boundary conditions make it possible to determine displacements and stress-strain state (including residual one) in materials of the composition of flexible cylindrical shells with varying degrees of accuracy. In this case, the weak resistance of the considered composite structures to transverse shears is taken into account. In the first approximation, the equations are used, the initial and boundary conditions correspond to the relations of the widely used non-classical Reddy theory. A numerical solution of the initial-boundary-value problem posed is constructed using an explicit step-by-step "cross" scheme. The elastoplastic and viscoelastic-plastic dynamic deformation of a relatively thin long circular cylindrical shell is investigated. The structure is rationally reinforced in the circumferential direction and is loaded with an internal pressure of an explosive type. It has been demonstrated that under intense short-term loading even of a relatively thin cylindrical reinforced shell by internal pressure, the traditional Reddy theory does not guarantee that the maximum residual deflection and the intensity of residual deformations of the components of the composition are accurate to within 10% compared to calculations performed by the refined theory. The difference in the results of the corresponding calculations increases with an increase in the relative thickness of the composite shell. It was found that after plastic deformation of a long reinforced cylindrical shell in its residual state, not only appear zones of edge effects, but also a local zone of an intense deformation located in the vicinity of the central section of the shell. The length of the local central zone is comparable with the length of the zones of edge effects. It is shown that the amplitude of the transverse vibrations of the reinforced shell in the vicinity of the initial moment of time significantly (by an order of magnitude) exceeds the value of the maximum modulus of the residual deflection. Therefore, the calculations performed in the framework of the theory of elastoplastic deformation of composition materials do not allow a very approximate determination of the magnitude of the residual displacements and the magnitude of the residual deformed state of the components of the composition of the cylindrical shell.
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Meyer, J. W., and J. H. Bonin. "Performance and Flowrate Control of the Kinetic Extruder Coal Powder Pump." Journal of Engineering for Gas Turbines and Power 107, no. 3 (July 1, 1985): 652–60. http://dx.doi.org/10.1115/1.3239785.
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The kinetic extruder is a novel centrifugal machine for feeding powdered material, in particular coal, against gas back pressure. The nonmechanical method of flow-rate control in the machine is described. Performance data obtained in tests of the kinetic extruder are presented and compared with theoretical predictions. It is found that a one-dimensional model of the material flow through the device gives accurate predictions of most aspects of the machine’s performance. However, some details of the limiting behavior evidently require a more refined analysis.
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Sheng, Chunquan, Zhenyuan Miao, Haitao Ji, Jianzhong Yao, Wenya Wang, Xiaoying Che, Guoqiang Dong, Jiaguo Lü, Wei Guo, and Wannian Zhang. "Three-Dimensional Model of Lanosterol 14α-Demethylase from Cryptococcus neoformans: Active-Site Characterization and Insights into Azole Binding." Antimicrobial Agents and Chemotherapy 53, no. 8 (May 26, 2009): 3487–95. http://dx.doi.org/10.1128/aac.01630-08.
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ABSTRACT Cryptococcus neoformans is one of the most important causes of life-threatening fungal infections in immunocompromised patients. Lanosterol 14α-demethylase (CYP51) is the target of azole antifungal agents. This study describes, for the first time, the 3-dimensional model of CYP51 from Cryptococcus neoformans (CnCYP51). The model was further refined by energy minimization and molecular-dynamics simulations. The active site of CnCYP51 was well characterized by multiple-copy simultaneous-search calculations, and four functional regions important for rational drug design were identified. The mode of binding of the natural substrate and azole antifungal agents with CnCYP51 was identified by flexible molecular docking. A G484S substitution mechanism for azole resistance in CnCYP51, which might be important for the conformation of the heme environment, is suggested.
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Li, Qiang, and Liyang Xie. "Analysis and Optimization of Tooth Surface Contact Stress of Gears with Tooth Profile Deviations, Meshing Errors and Lead Crowning Modifications Based on Finite Element Method and Taguchi Method." Metals 10, no. 10 (October 14, 2020): 1370. http://dx.doi.org/10.3390/met10101370.
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Based on the three-dimensional (3D) finite element method (FEM) and Taguchi method (TM), this paper analyzes the tooth surface contact stress (TSCS) of spur gears with three different influence factors: tooth profile deviations (TPD), meshing errors (ME) and lead crowning modifications (LCM), especially researching and analyzing the interactions between TPD, ME and LCM and their degree of influence on the TSCS. In this paper, firstly, a 3D FEM model of one pair of engaged teeth is modeled and the mesh of the contact area is refined by FEM software. In the model, the refined area mesh and the non-refined area mesh are connected by multi-point constraint (MPC); at the same time, in order to save the time of the FEM solution on the premise of ensuring the solution’s accuracy, the reasonable size of the refined area is studied and confirmed. Secondly, the TSCS analyses of gears with one single influence factor (other factors are all ideal) are carried out. By inputting the values of different levels of one single factor into the FEM model, especially using the real measurement data of TPD, and conducting the TSCS analysis under different torques, the influence degree of one single factor on TSCS is discussed by comparing the ideal model, and it is found that when the influence factors exist alone, each factor has a great influence on the TSCS. Finally, through TM, an orthogonal test is designed for the three influence factors. According to the test results, the interactions between the influence factors and the influence degree of the factors on the TSCS are analyzed when the three factors exist on the gear at the same time, and it is found that the TPD has the greatest influence on the TSCS, followed by the lead crowning modified quantity. The ME is relatively much small, and there is obvious interaction between ME and LCM. In addition, the optimal combination of factor levels is determined, and compared with the original combination of a gear factory, we see that the contact fatigue performance of the gear with the optimal combination is much better. The research of this paper has a certain reference significance for the control of TPD, ME and LCM when machining and assembling the gears.
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Zhao, Ya-Yun, Xiu-Hua Zhao, Jie Zhang, Jian-Guo Pan, and Xing Li. "Electrochemical properties of a cobalt(II) complex with sulfadiazine and 1,3-bis(pyridin-4-yl)propane." Acta Crystallographica Section C Crystal Structure Communications 69, no. 10 (September 6, 2013): 1096–99. http://dx.doi.org/10.1107/s010827011302297x.
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catena-Poly[[bis{4-[(pyrimidin-2-ylazanidyl)sulfonyl]aniline}cobalt(II)]-bis[μ-1,3-bis(pyridin-4-yl)propane]], [Co(C10H8N4O4S2)2(C13H14N2)]nor [Co(L)2(bpp)]n, crystallizes as a one-dimensional polymeric structure which is further stabilized by intermolecular hydrogen bonding. The refined Flack parameter, −0.001 (10), indicates that the model represents the correct absolute structure. Investigation of the thermal stability shows that the complex is stable up to 543 K. The structure is of interest with respect to its electrochemical properties in the reduction reaction of H2O2to H2O.
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Setifi, Zouaoui, Fatima Setifi, Necmi Dege, Rafika El Ati, and Christopher Glidewell. "Redetermination of the crystal structure of bis(tri-2-pyridylamine)iron(II) bis(perchlorate), and a new refinement of the isotypic nickel(II) analogue: treatment of the perchlorate anion disorder." Acta Crystallographica Section E Crystallographic Communications 74, no. 5 (April 17, 2018): 668–72. http://dx.doi.org/10.1107/s2056989018005601.
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The redetermination of the structure of the title compound, [Fe(C15H12N4)2](ClO4)2, (I), confirms the structure previously reported [Kucharski et al. (1978a). Aust. J. Chem. 31, 53–56], but models the perchlorate over four sets of atomic sites, rather than using just one set of sites as in the original report. The supramolecular assembly, not reported previously, takes the form of a complex three-dimensional framework built from C—H...O hydrogen bonds. The isotypic nickel(II) analogue, [Ni(C15H12N4)2](ClO4)2, (III), has been refined using the original data set [Wang et al. (2011). Acta Cryst. E67, m78], again using a four-component disorder model for the anion, rather than a two-component model as in the original report, leading to more satisfactory Cl—O distances and O—Cl—O angles.
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Sobhy, Mohammed, and Ashraf M. Zenkour. "Refined Lord–Shulman Theory for 1D Response of Skin Tissue under Ramp-Type Heat." Materials 15, no. 18 (September 10, 2022): 6292. http://dx.doi.org/10.3390/ma15186292.
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In this article, we present a mathematical model of thermoelastic skin tissue based on a refined Lord–Shulman heat conduction theory. A small thickness of skin tissue is considered to be one-dimensional with mechanical clamped surfaces. In addition, the skin tissue’s outer surface is subjected to ramp-type heating while its inner surface is adiabatic. A simple Lord–Shulman theory, as well as the classical coupled thermoelasticity, are also applied in this article. Laplace transform techniques and their inversions are calculated to return to the time domain. Numerical outcomes are represented graphically to discuss the significant impacts on the temperature, dilatation, displacement, and stress distributions. Such results provide a more comprehensive and better insight for understanding the behavior of skin tissue during the temperature distribution of a specific boundary condition.
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Jin, Dan Dan, Guo Xing Chen, and Fei Fan Dong. "Large-Scale Two-Dimensional Nonlinear Analysis on Seismic Effect of Fuzhou Basin." Applied Mechanics and Materials 90-93 (September 2011): 1426–33. http://dx.doi.org/10.4028/www.scientific.net/amm.90-93.1426.
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So far, nonlinear analyses on seismic effect of large-scale basin model have rarely been reported. Based on the explicit finite element method and 32 CPU parallel computing cluster platform of ABAQUS, a two-dimensional（2D） large-scale refined model for Fuzhou Basin is established using a nonlinear analytical method in the time domain. Both the peak ground acceleration (PGA) and acceleration response spectra of ground surface are emphatically analyzed. Meanwhile, the results by one-dimensional equivalent linearization method in frequency domain are added for the sake of contrast. The study results show that the PGA of ground surface will be obviously amplified when compared with the peak acceleration of bedrock ground motion; and the ground acceleration response spectra of Fuzhou Basin may appear a double-peak or multi-peak phenomenon. Moreover, the 2D large-scale model can reflect amplification effect of Fuzhou Basin soil to bedrock ground motion in particular periods; In addition, the acceleration responses of ground surface right above the bedrock valleys and crests appear larger than the other positions adjacent to them, these phenomenon are generally manifested as focusing effect and amplification effect, which are thought to be produced by the recently deposited soils in the basins as well as the special soil layer such as lens. In general, the PGA of ground surface obtained by 2D model present to be greater than that obtained by the one-dimensional model.
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Pagani, A., R. Azzara, R. Augello, E. Carrera, and B. Wu. "Accurate through-the-thickness stress distributions in thin-walled metallic structures subjected to large displacements and large rotations." Vietnam Journal of Mechanics 42, no. 3 (September 27, 2020): 239–54. http://dx.doi.org/10.15625/0866-7136/15042.
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The present paper presents the evaluation of three-dimensional (3D) stress distributions of shell structures in the large displacement and rotation fields. The proposed geometrical nonlinear model is based on a combination of the Carrera Unified Formulation (CUF) and the Finite Element Method (FEM). Besides, a Newton-Raphson linearization scheme is adopted to compute the geometrical nonlinear equations, which are constrained using the arc-length path-following method. Static analyses are performed using refined models and the full Green-Lagrange strain-displacement relations. The Second Piola-Kirchhoff (PK2) stress distributions are evaluated, and lower- to higher-order expansions are employed. Popular benchmarks problems are analyzed, including cylindrical isotropic shell structure with various boundary and loading conditions. Various numerical assessments for different equilibrium conditions in the moderate and large displacement fields are proposed. Results show the distribution of axial and shear stresses, varying the refinement of the proposed two-dimensional (2D) shell model. It is shown that for axial components, a lower-order expansion is sufficient, whereas a higher-order one is needed to accurately predict shear stresses.
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Lourenço, Diana, Raquel Lopes, Carolina Pestana, Ana C. Queirós, Cristina João, and Emilie Arnault Carneiro. "Patient-Derived Multiple Myeloma 3D Models for Personalized Medicine—Are We There Yet?" International Journal of Molecular Sciences 23, no. 21 (October 25, 2022): 12888. http://dx.doi.org/10.3390/ijms232112888.
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Despite the wide variety of existing therapies, multiple myeloma (MM) remains a disease with dismal prognosis. Choosing the right treatment for each patient remains one of the major challenges. A new approach being explored is the use of ex vivo models for personalized medicine. Two-dimensional culture or animal models often fail to predict clinical outcomes. Three-dimensional ex vivo models using patients’ bone marrow (BM) cells may better reproduce the complexity and heterogeneity of the BM microenvironment. Here, we review the strengths and limitations of currently existing patient-derived ex vivo three-dimensional MM models. We analyze their biochemical and biophysical properties, molecular and cellular characteristics, as well as their potential for drug testing and identification of disease biomarkers. Furthermore, we discuss the remaining challenges and give some insight on how to achieve a more biomimetic and accurate MM BM model. Overall, there is still a need for standardized culture methods and refined readout techniques. Including both myeloma and other cells of the BM microenvironment in a simple and reproducible three-dimensional scaffold is the key to faithfully mapping and examining the relationship between these players in MM. This will allow a patient-personalized profile, providing a powerful tool for clinical and research applications.
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Voglhuber-Brunnmaier, Thomas, and Bernhard Jakoby. "Higher-Order Models for Resonant Viscosity and Mass-Density Sensors." Sensors 20, no. 15 (July 31, 2020): 4279. http://dx.doi.org/10.3390/s20154279.
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Advanced fluid models relating viscosity and density to resonance frequency and quality factor of vibrating structures immersed in fluids are presented. The numerous established models which are ultimately all based on the same approximation are refined, such that the measurement range for viscosity can be extended. Based on the simple case of a vibrating cylinder and dimensional analysis, general models for arbitrary order of approximation are derived. Furthermore, methods for model parameter calibration and the inversion of the models to determine viscosity and/or density from measured resonance parameters are shown. One of the two presented fluid models is a viscosity-only model, where the parameters of it can be calibrated without knowledge of the fluid density. The models are demonstrated for a tuning fork-based commercial instrument, where maximum deviations between measured and reference viscosities of approximately ±0.5% in the viscosity range from 1.3 to 243 mPas could be achieved. It is demonstrated that these results show a clear improvement over the existing models.
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Aljadani, Maryam H., and Ashraf M. Zenkour. "A Modified Two-Relaxation Thermoelastic Model for a Thermal Shock of Rotating Infinite Medium." Materials 15, no. 24 (December 18, 2022): 9056. http://dx.doi.org/10.3390/ma15249056.
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A unified form of thermoelasticity theory that contains three familiar generalized thermoelasticity. The Lord–Shulman theory, Green–Lindsay theory, and the classical one can be outlined in this form. The field quantities of a rotating/non-rotating half-space with and without the effect of the decay parameter can be obtained due to the unified thermoelasticity theory. The present medium is subjected to a time-dependent thermal shock taking into account that the magnitude of the thermal shock wave is not totally fixed but decaying over time. A special case of a thermal shock waveform with constant magnitude may be considered. The field quantities such as temperature, displacements, and stresses of the present problem are analytically obtained. Some plots of these field variables are presented in two- and three-dimensional illustrations in the context of refined theories.
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Iwata, Tomoyuki, Tatsuya Horie, and Koichiro Fukuda. "Reinvestigation of crystal structure and structural disorder of Ba3MgSi2O8." Powder Diffraction 24, no. 3 (September 2009): 180–84. http://dx.doi.org/10.1154/1.3193522.
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Crystal structure and structural disorder of Ba3MgSi2O8 were reinvestigated by laboratory X-ray powder diffraction. The title compound was found to be trigonal with space group P3m1, Z=1, and unit-cell dimensions a=0.561 453(4) nm, c=0.727 629(4) nm, and V=0.198 641(2) nm3. The initial structural model used for structure refinement was taken from that of glaserite (K3NaS2O8) and modified by a split-atom model. In the split-atom model, one of the two types of Ba sites and that of SiO4 tetrahedra were, respectively, positionally and orientationally disordered. The new crystal structure and structural disorder were refined by the Rietveld method. The maximum-entropy-method-based pattern fitting (MPF) method was used to confirm the validity of the split-atom model, in which conventional structure bias caused by assuming intensity partitioning was minimized. The final reliability indices calculated from MPF were Rwp=6.52%, S=1.36, Rp=4.84%, RB=0.97%, and RF=0.52%. Details of the disorder structure of Ba3MgSi2O8 are shown in the three-dimensional and two-dimensional electron-density distribution maps determined by MPF.
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Lucchesi, Massimiliano, Barbara Pintucchi, and Nicola Zani. "An Enhanced Beam Model for the Analysis of Masonry Walls." Open Construction and Building Technology Journal 13, no. 1 (March 28, 2019): 52–66. http://dx.doi.org/10.2174/1874836801913010052.
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Background: Some typologies of masonry constructions (e.g. towers or walls with openings) can be reasonably studied through simple beam or frame-like models. For these structures, shear mechanisms often play an important role inducing failure and collapse. Objective: The paper presents an enriched beam model for studying the in-plane response of masonry walls. Initially formulated for masonry columns, towers and masonry slender structures in general, the model is now modified in order to also capture the shear failure mechanisms, in addition to the flexural ones. Methods: Starting with a one-dimensional no-tension model, a strength domain in the plane of the axial and tangential stress of the beam has been added, which has been defined by limiting both the stress shear component with respect to any possible direction and the main compressive stress. Results: The model, implemented in the FEM computational code MADY, allows for short computational times in studying the response of single panels as well as walls with openings. Conclusion: Comparisons with some experimental results from literature and some numerical results from more refined 2D models show the effectiveness and accuracy of the model’s predictions in terms of global and local response.
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Wang, Fang. "Analysis of an Online English Teaching Model Application Based on Improved Multiorganizational Particle Population Optimization Algorithm." Computational Intelligence and Neuroscience 2021 (December 16, 2021): 1–11. http://dx.doi.org/10.1155/2021/6232987.
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This paper uses an improved multiorganizational particle population optimization algorithm to conduct an in-depth analysis and study of an online English teaching model and uses the altered model for practical applications. The model building elements are extracted from it for the initial construction of a blended learning model of English-speaking teaching in junior high school. The main purpose of the first round of action research is to test the rationality of each element of the model, the main purpose of the second round of action research is to refine the model links and improve the operability of the model, and the main purpose in the third round of action research is to test the perfected model and explore the model. The main purpose of the third round of action research is to test the refined model and explore the application suggestions of the model. After the three rounds of action research, we finally obtained a more mature blended learning model for teaching English as a foreign language in junior high school. Mainly through the comparison of the pre- and posttest scores of English speaking of the experimental subjects and the comparison of the pre- and posttest data of the relevant questionnaires, the following experimental conclusions were drawn: adopting the blended learning-based speaking teaching model can effectively improve students’ interest in learning English, their attitudes and their English speaking skills including pronunciation, phonetic intonation, conversational communication, and oral expression and can enhance students’ group cooperation and communication ability, independent learning ability, evaluation awareness, and ability. This single-guided learning mechanism can effectively avoid the shocks that are easily caused by the dual-guided role of traditional PSO. The dimensional learning strategy constructs a learning paradigm for each particle by learning from each dimension of the individual optimal position of the particle to the corresponding dimension of the group optimal position, respectively. Dimensional learning is formally integrated into the learning paradigm only if it can improve the fitness of the paradigm so that the dimensional learning strategy can avoid the phenomenon of degradation of the learning paradigm and the phenomenon of “two steps forward, one step back.” In the dimensional learning strategy, since each particle learns from best, although it has a strong exploitation capability, it may cause all particles to converge to best quickly, making the algorithm converge prematurely.
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Gurtovyi, O., and S. Tynchuk. "INVESTIGATION DEFORMATION OF A MULTILAYERED TRANSVERSAL-ISOTROPIC PLATE ON A RIGID FOUNDATION BY UNFLEXURAL REFINED CONTINUAL MODEL." Mechanics And Mathematical Methods 4, no. 1 (June 2022): 64–74. http://dx.doi.org/10.31650/2618-0650-2022-4-1-64-74.
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The high-precision estimation of the stress-strain state (SSS) of multilayered plates on a rigid foundation under the action of stationary transverse loading is an urgent task. As its includes the calculations of strength and deformability of various homogeneous and multilayer coatings. This is the calculation of road surface on relatively rigid bridge structures, or on a non-deformable underlying layer or calculation protective multilayer coatings of flat structural elements of greater rigidity than coatings, etc. The combining of materials with isotropic and transversal-isotropic physical characteristics into a multilayer package allows creating of the multifunctional designs. The SSS of such structures due to their structural heterogeneity and the relatively low transverse stiffness of the individual layers is significantly associated with the effect of transverse shear deformations and transverse compression deformations. Therefore, the problem of refined modelling of SSS of plates, which takes into account these types of deformations, is an urgent one. Based on the decomposition the SSS of plate into the flexural and unflexural components, it is proposed to optimize the design diagram of deformation a rectangular multilayer plate on a rigid foundation. The essence of optimization is to consider such a design diagram of the plate, in which the SSS of plate would be fully described by only one component, namely the unflexural component of SSS. To do this, instead of the actual design of the multilayer plate, which is deformed without separation from the foundation, it is suggested to consider the design diagram of the plate, which is formed by supplementing it with a symmetric one about the contact surface of the foundation. In this case, the plate will be symmetrically loaded with respect to the middle surface of the plate, and the thickness of the plate will double. The SSS of plate will be unflexural, which greatly simplifies its modeling. For unflexural SSS, a twodimensional and high-degree iterative approximation but three-dimensional by the nature reflection of SSS, model of deformation of multilayer rectangular plates on a rigid foundation with isotropic and transverse-isotropic layers is constructed in an elastic formulation. This model takes full account deformations of transverse shear and of transverse compression at transverse loading of a plate. Calculations of homogeneous and two-layer transverse-isotropic plates on a rigid foundation under the action evenly distributed and localized transverse loads on the surface of a plate are performed by the finite difference method.
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Bindi, L., P. Voudouris, and P. G. Spry. "Structural role of tellurium in the minerals of the pearceite-polybasite group." Mineralogical Magazine 77, no. 4 (June 2013): 419–28. http://dx.doi.org/10.1180/minmag.2013.077.4.02.
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AbstractThe crystal structure of a Te-rich polybasite has been refined by means of X-ray diffraction data collected at room temperature (space group Pm1; R = 0.0505 for 964 observed reflections and 94 parameters; refined formula Ag14.46Cu1.54Sb1.58As0.42S9.67Te1.33). The structure comprises stacking of [(Ag, Cu)6(Sb, As)2(S, Te)7]2–A and [Ag9Cu(S, Te)2(S, Te)2]2+B layer modules in which Sb forms isolated SbS3 pyramids, as occurs typically in sulfosalts, Cu links two S atoms in a linear coordination and Ag occupies sites with coordination ranging from quasi linear to almost tetrahedral. The silver d10 ions are found in the B layer module along two-dimensional diffusion paths and their electron densities evidenced by means of a combination of a Gram-Charlier development of the atomic displacement factors and a split model. The Te-for-S substitution occurs at the same structural sites that Se substitutes for S in selenopolybasite and the Te occupancy at one of these sites is 0.49, thus suggesting the possibility that 'telluropolybasite' could be found in nature.
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Olek, Bartłomiej Szczepan. "A Consolidation Curve Reproduction Based on Sigmoid Model: Evaluation and Statistical Assessment." Materials 15, no. 18 (September 6, 2022): 6188. http://dx.doi.org/10.3390/ma15186188.
Full textAbstract:
In the present study, various shapes of laboratory consolidation curves were numerically reproduced using a four-parametric sigmoid function. Sixteen consolidation curves were selected based on one-dimensional oedometer tests to statistically evaluate the sigmoid model and to determine the appropriate deviation statistics. Comparisons between observed and predicted data were performed using the following statistical metrics: mean error (E), root mean square error (RMSE), mean absolute error (MAE), weighted error (WE), revised Nash–Sutcliffe efficiency index (CE1) and refined index of model performance (dr). The weighted error (WE) was chosen as the optimization target in a first-order iterative optimization algorithm to determine a local minimum of a differentiable function. Comparing the simulated and observed settlements showed close correspondence in the values of CE1 and dr in terms of model performance. Based on statistical assessment, the maximum values of RMSE and MAE for the average degree of consolidation were 0.029 (-) and 0.021 (-), respectively. In turn the settlement data RMSE and MAE were 0.039 mm and 0.025 mm, respectively. These results indicated that the sigmoid expression effectively reproduced the shape of the consolidation curve.
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Jena, Subrat Kumar, S. Chakraverty, Mohammad Malikan, and Hamid Mohammad-Sedighi. "Hygro-Magnetic Vibration of the Single-Walled Carbon Nanotube with Nonlinear Temperature Distribution Based on a Modified Beam Theory and Nonlocal Strain Gradient Model." International Journal of Applied Mechanics 12, no. 05 (June 2020): 2050054. http://dx.doi.org/10.1142/s1758825120500544.
Full textAbstract:
In this study, vibration analysis of single-walled carbon nanotube (SWCNT) has been carried out by using a refined beam theory, namely one variable shear deformation beam theory. This approach has one variable lesser than a contractual shear deformation theory such as first-order shear deformation theory (FSDT) and acts like classical beam approach but with considering shear deformations. The SWCNT has been placed in an axial or longitudinal magnetic field which is also exposed to both the hygroscopic as well as thermal environments. The thermal environment is considered as nonlinear thermal stress field based on the Murnaghan’s model whereas the hygroscopic environment is assumed as a linear stress field. The size effect of the SWCNT has been captured by both the nonlocal and gradient parameters by employing the Nonlocal Strain Gradient Theory (NSGT). Governing equation of motion of the proposed model has been developed by utilizing the extended Hamilton’s principle and the non-dimensional frequency parameters have been computed by incorporating the Navier’s approach for Hinged–Hinged (HH) boundary condition. The proposed model is validated with the existing model in special cases, by comparing the non-dimensional frequency parameters, displaying an excellent agreement. Further, a parametric study has been conducted to analyze the impact of nonlocal parameter, gradient parameter, thermal environment, hygroscopic environment, and magnetic field intensity on the non-dimensional frequency parameters. Also, results for some other theories like Classical Elasticity Theory (CET), Nonlocal Elasticity Theory (NET), and Strain Gradient Theory (SGT) have been presented along with the NSGT.
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Wang, Yingxu. "Classic Probability Revisited (I): Mathematical Models of an Extended Probability Theory." PROOF 2 (March 17, 2022): 77–85. http://dx.doi.org/10.37394/232020.2022.2.10.
Full textAbstract:
Part I of this paper presents a set of extended mathematical models of probability theory in order to explain the nature, properties, and rules of general probability. It is found that probability is a hyperstructure beyond those of the traditional monotonic and one-dimensional discrete structures. The sample space of probability is not invariant in general cases. Types of vents in the sample space may be refined as joint or disjoint and dependent, independent, or mutuallyexclusive. These newly identified properties lead to a three-dimensional dynamic model of probability structures constrained by the type of sample spaces, the relation of events, and the dependency of events. A set of algebraic operators on the mathematical structures of the general probability theory is derived based on the extended mathematical models of probability. It is revealed that the Bayes’ law needs to be extended in order to fit more general contexts on variant sample spaces and complex event properties in fundamental probability theories. The revisited probability theory enables a rigorous treatment of uncertainty events and causations in formal inference, qualification, quantification, and semantic analysis in contemporary fields such as cognitive informatics, computational intelligence, cognitive robots, complex systems, soft computing, and brain informatics.
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Chavarrías, Víctor, Ralph Schielen, Willem Ottevanger, and Astrid Blom. "Ill posedness in modelling two-dimensional morphodynamic problems: effects of bed slope and secondary flow." Journal of Fluid Mechanics 868 (April 11, 2019): 461–500. http://dx.doi.org/10.1017/jfm.2019.166.
Full textAbstract:
A two-dimensional model describing river morphodynamic processes under mixed-size sediment conditions is analysed with respect to its well posedness. Well posedness guarantees the existence of a unique solution continuously depending on the problem data. When a model becomes ill posed, infinitesimal perturbations to a solution grow infinitely fast. Apart from the fact that this behaviour cannot represent a physical process, numerical simulations of an ill-posed model continue to change as the grid is refined. For this reason, ill-posed models cannot be used as predictive tools. One source of ill posedness is due to the simplified description of the processes related to vertical mixing of sediment. The current analysis reveals the existence of two additional mechanisms that lead to model ill posedness: secondary flow due to the flow curvature and the effect of gravity on the sediment transport direction. When parametrising secondary flow, accounting for diffusion in the transport of secondary flow intensity is a requirement for obtaining a well-posed model. When considering the theoretical amount of diffusion, the model predicts instability of perturbations that are incompatible with the shallow water assumption. The effect of gravity on the sediment transport direction is a necessary mechanism to yield a well-posed model, but not all closure relations to account for this mechanism are valid under mixed-size sediment conditions. Numerical simulations of idealised situations confirm the results of the stability analysis and highlight the consequences of ill posedness.
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Bouznik, V. M., S. D. Kirik, L. A. Solovyov, and A. K. Tsvetnikov. "A crystal structure of ultra-dispersed form of polytetrafluoroethylene based on X-ray powder diffraction data." Powder Diffraction 19, no. 3 (September 2004): 219–24. http://dx.doi.org/10.1154/1.1707037.
Full textAbstract:
An X-Ray powder diffraction study of ultra-dispersed polytetrafluoroethylene was carried out. As well as a regular polytetrafluoroethylene the ultra-dispersed form contents a high proportion of the crystalline phase. The X-ray diffraction pattern could be described with two-dimensional hexagonal unit cell [a=5.685(1) Å, symmetry group p6mm]. Structural modeling with a continuous electron density approach as well as with a discrete disordered atoms distribution was accomplished. The model was refined using the Rietveld method. The structure is characterized by a spiral arrangement of polymers (CF2-)n along the z-axis with complete mutual disordering by rotational displacement around z, as well as a partial molecular translation along the z-axis. Molecular disordering results in a systematic absence of reflections with 1≠0 and as a sequence in two-dimensional unit cell effect. The presence of complete rotational disordering distinguishes the ultra-dispersed form of polytetrafluoroethylene from the standard one (fluoroplast-4), where only partial disordering is observed.