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Liu, Renwei, Dongjie Wang, Xinyu Zhang, Wang Li und Bo Yu. „Comparison Study on the Performances of Finite Volume Method and Finite Difference Method“. Journal of Applied Mathematics 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/596218.
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Vorticity-stream function method and MAC algorithm are adopted to systemically compare the finite volume method (FVM) and finite difference method (FDM) in this paper. Two typical problems—lid-driven flow and natural convection flow in a square cavity—are taken as examples to compare and analyze the calculation performances of FVM and FDM with variant mesh densities, discrete forms, and treatments of boundary condition. It is indicated that FVM is superior to FDM from the perspective of accuracy, stability of convection term, robustness, and calculation efficiency. Particularly ,when the mesh is coarse and taken as20×20, the results of FDM suffer severe oscillation and even lose physical meaning.
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Czyz, Marcin, Hesham Radwan, Jian Y. Li, Christopher G. Filippi, Tomasz Tykocki und Michael Schulder. „Fractal Analysis May Improve the Preoperative Identification of Atypical Meningiomas“. Neurosurgery 80, Nr. 2 (07.12.2016): 300–308. http://dx.doi.org/10.1093/neuros/nyw030.
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Abstract BACKGROUND: There is no objective and readily accessible method for the preoperative determination of atypical characteristics of a meningioma grade. OBJECTIVE: To evaluate the feasibility of using fractal analysis as an adjunctive tool to conventional radiological techniques in visualizing histopathological features of meningiomas. METHODS: A group of 27 patients diagnosed with atypical (WHO grade II) meningioma and a second group of 27 patients with benign (WHO grade I) meningioma were enrolled in the study. Preoperative brain magnetic resonance (MR) studies (T1-wieghted, post-gadolinium) were processed and analyzed to determine the average fractal dimension (FDa) and maximum fractal dimension (FDm) of the contrast-enhancing region of the tumor using box-count method. FDa and FDm as well as particular radiological features were included in the logistic regression model as possible predictors of malignancy. RESULTS: The cohort consisted of 34 women and 20 men, mean age of 62 ± 15 yr. Fractal analysis showed good interobserver reproducibility (Kappa >0.70). Both FDa and FDm were significantly higher in the atypical compared to the benign meningioma group (P < .0001). Multivariate logistic regression model reached statistical significance with P = .0001 and AUC = 0.87. The FDm, which was greater than 1.31 (odds ratio [OR], 12.30; P = .039), and nonskull base localization (OR, .052; P = .015) were confirmed to be statistically significant predictors of the atypical phenotype. CONCLUSION: Fractal analysis of preoperative MR images appears to be a feasible adjunctive diagnostic tool in identifying meningiomas with potentially aggressive clinical behavior.
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Bommaraju, C., R. Marklein und P. K. Chinta. „Optimally Accurate Second-Order Time-Domain Finite-Difference Scheme for Acoustic, Electromagnetic, and Elastic Wave Modeling“. Advances in Radio Science 3 (12.05.2005): 175–81. http://dx.doi.org/10.5194/ars-3-175-2005.
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Abstract. Numerical methods are extremely useful in solving real-life problems with complex materials and geometries. However, numerical methods in the time domain suffer from artificial numerical dispersion. Standard numerical techniques which are second-order in space and time, like the conventional Finite Difference 3-point (FD3) method, Finite-Difference Time-Domain (FDTD) method, and Finite Integration Technique (FIT) provide estimates of the error of discretized numerical operators rather than the error of the numerical solutions computed using these operators. Here optimally accurate time-domain FD operators which are second-order in time as well as in space are derived. Optimal accuracy means the greatest attainable accuracy for a particular type of scheme, e.g., second-order FD, for some particular grid spacing. The modified operators lead to an implicit scheme. Using the first order Born approximation, this implicit scheme is transformed into a two step explicit scheme, namely predictor-corrector scheme. The stability condition (maximum time step for a given spatial grid interval) for the various modified schemes is roughly equal to that for the corresponding conventional scheme. The modified FD scheme (FDM) attains reduction of numerical dispersion almost by a factor of 40 in 1-D case, compared to the FD3, FDTD, and FIT. The CPU time for the FDM scheme is twice of that required by the FD3 method. The simulated synthetic data for a 2-D P-SV (elastodynamics) problem computed using the modified scheme are 30 times more accurate than synthetics computed using a conventional scheme, at a cost of only 3.5 times as much CPU time. The FDM is of particular interest in the modeling of large scale (spatial dimension is more or equal to one thousand wave lengths or observation time interval is very high compared to reference time step) wave propagation and scattering problems, for instance, in ultrasonic antenna and synthetic scattering data modeling for Non-Destructive Testing (NDT) applications, where other standard numerical methods fail due to numerical dispersion effects. The possibility of extending this method to staggered grid approach is also discussed. The numerical FD3, FDTD, FIT, and FDM results are compared against analytical solutions.
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Long, Jingjunjiao, Hamideh Gholizadeh, Jun Lu, Craig Bunt und Ali Seyfoddin. „Application of Fused Deposition Modelling (FDM) Method of 3D Printing in Drug Delivery“. Current Pharmaceutical Design 23, Nr. 3 (20.02.2017): 433–39. http://dx.doi.org/10.2174/1381612822666161026162707.
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Three-dimensional (3D) printing is an emerging manufacturing technology for biomedical and pharmaceutical applications. Fused deposition modelling (FDM) is a low cost extrusion-based 3D printing technique that can deposit materials layer-by-layer to create solid geometries. This review article aims to provide an overview of FDM based 3D printing application in developing new drug delivery systems. The principle methodology, suitable polymers and important parameters in FDM technology and its applications in fabrication of personalised tablets and drug delivery devices are discussed in this review. FDM based 3D printing is a novel and versatile manufacturing technique for creating customised drug delivery devices that contain accurate dose of medicine( s) and provide controlled drug released profiles.
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Gupta, Dr A. R. „Comparative analysis of Rectangular Plate by Finite element method and Finite Difference Method“. International Journal for Research in Applied Science and Engineering Technology 9, Nr. 9 (30.09.2021): 1397–98. http://dx.doi.org/10.22214/ijraset.2021.38152.
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Abstract: Plates are commonly used to support lateral or vertical loads. Before the design of such a plate, analysis is performed to check the stability of plate for the proposed load. There are several methods for this analysis. In this research, a comparative analysis of rectangular plate is done between Finite Element Method (FEM) and Finite Difference Method (FDM). The plate is considered to be subjected to an arbitrary transverse uniformly distributed loading and is considered to be clamped at the two opposite edges and free at the other two edges. The Finite Element Method (FEM) is a numerical technique for finding approximate solutions to boundary value problems for partial differential equations. It is also referred to as finite element analysis (FEA). FEM subdivides a large problem into smaller, simpler, parts, called finite elements. The work covers the determination of displacement components at different points of the plate and checking the result by software (STAAD.Pro) analysis. The ordinary Finite Difference Method (FDM) is used to solve the governing differential equation of the plate deflection. The proposed methods can be easily programmed to readily apply on a plate problem. Keywords: Arbitrary, FEM, FDM, boundary.
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Gębura, Andrzej, Jerzy Borowski, Bogdan Pietnoczko, Jan Darowski, Mieczysław Pigłas und Ewelina Siekierska. „Analysis of measuring apparatus errors using the FAM-C and FDM-A methods“. Journal of KONBiN 50, Nr. 4 (01.12.2020): 217–36. http://dx.doi.org/10.2478/jok-2020-0083.
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Abstract The article discusses the errors of the electronic measuring apparatus built at AFIT using the FAM-C and FDM-A methods, dedicated to monitoring the technical condition of aircraft power units. The basic components and variants of the use of the built electronic apparatus are presented: the optimization of the selection of construction parameters and the change of the error level in the selection of various types of construction of a given system. The influence of external factors on errors of the measuring system was also described, including changes in the amplitude of the electrical power generator output signal and the influence of the carrier frequency depending on the phase configuration of the measuring system. The method of comprehensive checking of electronic measuring equipment for FAM-C and FDM-A methods in laboratory conditions was presented.
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Singh, Pushpendra, Shiv Dutt Joshi, Rakesh Kumar Patney und Kaushik Saha. „The Fourier decomposition method for nonlinear and non-stationary time series analysis“. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 473, Nr. 2199 (März 2017): 20160871. http://dx.doi.org/10.1098/rspa.2016.0871.
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for many decades, there has been a general perception in the literature that Fourier methods are not suitable for the analysis of nonlinear and non-stationary data. In this paper, we propose a novel and adaptive Fourier decomposition method (FDM), based on the Fourier theory, and demonstrate its efficacy for the analysis of nonlinear and non-stationary time series. The proposed FDM decomposes any data into a small number of ‘Fourier intrinsic band functions’ (FIBFs). The FDM presents a generalized Fourier expansion with variable amplitudes and variable frequencies of a time series by the Fourier method itself. We propose an idea of zero-phase filter bank-based multivariate FDM (MFDM), for the analysis of multivariate nonlinear and non-stationary time series, using the FDM. We also present an algorithm to obtain cut-off frequencies for MFDM. The proposed MFDM generates a finite number of band-limited multivariate FIBFs (MFIBFs). The MFDM preserves some intrinsic physical properties of the multivariate data, such as scale alignment, trend and instantaneous frequency. The proposed methods provide a time–frequency–energy (TFE) distribution that reveals the intrinsic structure of a data. Numerical computations and simulations have been carried out and comparison is made with the empirical mode decomposition algorithms.
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Lee, Chaeyoung, Jisang Lyu, Eunchae Park, Wonjin Lee, Sangkwon Kim, Darae Jeong und Junseok Kim. „Super-Fast Computation for the Three-Asset Equity-Linked Securities Using the Finite Difference Method“. Mathematics 8, Nr. 3 (26.02.2020): 307. http://dx.doi.org/10.3390/math8030307.
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In this article, we propose a super-fast computational algorithm for three-asset equity-linked securities (ELS) using the finite difference method (FDM). ELS is a very popular investment product in South Korea. There are one-, two-, and three-asset ELS. The three-asset ELS is the most popular financial product among them. FDM has been used for pricing the one- and two-asset ELS because it is accurate. However, the three-asset ELS is still priced using the Monte Carlo simulation (MCS) due to the curse of dimensionality for FDM. To overcome the limitation of dimension for FDM, we propose a systematic non-uniform grid with an explicit Euler scheme and an optimal implementation of the algorithm. The computational time is less than 6 s. We perform standard ELS option pricing and compare the results from the fast FDM with the ones from MCS. The computational results confirm the superiority and practicality of the proposed algorithm.
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Novakova-Marcincinova, Ludmila, und Jozef Novak-Marcincin. „Testing of ABS Material Tensile Strength for Fused Deposition Modeling Rapid Prototyping Method“. Advanced Materials Research 912-914 (April 2014): 370–73. http://dx.doi.org/10.4028/www.scientific.net/amr.912-914.370.
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In paper are presented information about materials used for production of models by Fused Deposition Modeling (FDM) rapid prototyping technology. In today's rapid prototyping technologies the initial state of building material can be in solid, liquid or powder state. The current range materials include plastic, nylon, wax, resins, metals and ceramics. In FDM are mainly used as basic materials ABS - Acrylonitrile Butadiene Styrene, polyamide, polycarbonate, polyethylene and polypropylene. Main part of the paper is focused on experimental testing of Acrylonitrile Butadiene Styrene materials realized by different research teams and presents outputs of testing of ABS material in FDM technology realized by authors.
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Başhan, Ali. „A mixed methods approach to Schrödinger equation: Finite difference method and quartic B-spline based differential quadrature method“. An International Journal of Optimization and Control: Theories & Applications (IJOCTA) 9, Nr. 2 (31.07.2019): 223–35. http://dx.doi.org/10.11121/ijocta.01.2019.00709.
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The present manuscript include, finite difference method and quartic B-spline based differential quadrature method (FDM-DQM) to obtain the numerical solutions for the nonlinear Schr¨odinger (NLS) equation. For this purpose, firstly Schrödinger equation has been converted into coupled real value differential equations and then they have been discretized using special type of classical finite difference method namely, Crank-Nicolson scheme. After that, Rubin and Graves linearization techniques have been utilized and differential quadrature method has been applied. So, partial differential equation turn into algebraic equation system. Next, in order to be able to test the accuracy of the newly hybrid method, the error norms L2 and L? as well as the two lowest invariants I1 and I2 have been calculated. Besides those, the relative changes in those invariants have been given. Finally, the newly obtained numerical results have been compared with some of those available in the literature for similar parameters. This comparison has clearly indicated that the currently utilized method, namely FDM-DQM, is an effective and efficient numerical schemeand allowed us to propose to solve a wide range of nonlinear equations.
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Liu, Yijian, Ming Chen und Jihong Chen. „Practical Nozzle Temperature Control Method for Robot FDM Printing System“. Computer and Information Science 12, Nr. 3 (25.07.2019): 21. http://dx.doi.org/10.5539/cis.v12n3p21.
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Fused Deposition Modeling (FDM) technology in 3D printing has beendeveloped for many years. In this paper, a robot FDM 3D printingsystem is proposed and the nozzle temperature control issue isfocused primarily. The temperature measurement adopts a data driven modeling method andthe parameters of the measurement model are trained by the particle swarm optimization algorithm. A practical temperature control method is presented in which thetemperature control of nozzle is divided into two periods. Duringthe temperature flying period, the heating voltage is givenaccording to the current temperature value and its varying trend. In thefalling time of nozzle temperature, the corresponding controlvoltage value is provided correspondingly. Based on this practical control strategy, a partdesigned with Solidworks software is printed using the robot FDM printing system which validates theeffectiveness of the practical temperature control method.
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Choi, Bong Hak, Woo Jung Kim, Chong Du Cho, Si Young Kwak und Cheong Kil Choi. „FDM/FEM Hybrid Method with a Systematic Field Data Conversion Procedure for Thermal Stress Analysis in Casting Process“. Key Engineering Materials 326-328 (Dezember 2006): 1205–8. http://dx.doi.org/10.4028/www.scientific.net/kem.326-328.1205.
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Noticeably in casting and heat treatment process, computational methods are commonly engaged to predict process and mechanical characteristics such as solidification time, cooling speed, hardness and residual stress, in which analyzing thermo-mechanical coupled process necessitates such heat transfer, microstructure transformation, and stress. This paper proposes a FDM/FEM hybrid method for thermal stress analysis in casting process; taking advantage of each computational method, we use both FDM and FEM to analyze thermal stress. We use FDM to predict temperature distribution and microstructure and then transfer the result data to FEM to calculate thermal stress distribution. In this process, a systematic field data conversion procedure is developed for a successful data transfer. For the validation of this proposed method, numerical examples are presented and compared with antecedent experiment results. The interface data conversion program developed in this study can be used for any other program as well as FDM and FEM.
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Denisov, S. V., V. E. Lyalin und R. O. Sultanov. „Comparison of the Current Tubes Method with Normal Numerical Methods with the Two-Dimensional Filtration of the Marked Liquid“. Intellekt. Sist. Proizv. 16, Nr. 3 (11.10.2018): 129. http://dx.doi.org/10.22213/2410-9304-2018-3-129-135.
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В качестве широко используемого численного метода решения уравнений без учета дисперсионного члена был выбран метод конечных объемов (finite volume method или FVM). В работе представлено введение в суть метода применительно к области гидродинамики и его сравнение с другими численными методами. Метод конечных объемов первоначально развивался как особая формулировка метода конечных разностей (finite difference method или FDM). Показано, что для реализации метода конечных объемов может использоваться базис как метода конечных разностей (FDM), так и метода конечных элементов (finite element method или FEM). Метод конечных объемов использует понятие контрольного объема (control volume или ) и контрольной поверхности (control surface или ), поэтому иногда этот метод называют методом контрольного объема. При этом основное уравнение сохранения записывается в интегральном виде. Далее проводится дискретизация этого уравнения, которая в данном примере будет осуществляться методом конечных разностей (FDM). Показано, что при большом числе трубок тока решение на базе метода трубок тока является точным для случая отсутствия диффузии и может быть использовано для вычисления пространственной ошибки.
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Carrell, John, Garrett Gruss und Elizabeth Gomez. „Four-dimensional printing using fused-deposition modeling: a review“. Rapid Prototyping Journal 26, Nr. 5 (02.01.2020): 855–69. http://dx.doi.org/10.1108/rpj-12-2018-0305.
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Purpose This paper aims to provide a review of four-dimensional (4D) printing using fused-deposition modeling (FDM). 4D printing is an emerging innovation in (three-dimensional) 3D printing that encompasses active materials in the printing process to create not only a 3D object but also a 3D object that can perform an active function. FDM is the most accessible form of 3D printing. By providing a review of 4D printing with FDM, this paper has the potential in educating the many FDM 3D printers in an additional capability with 4D printing. Design/methodology/approach This is a review paper. The approach was to search for and review peer-reviewed papers and works concerning 4D printing using FDM. With this discussion of the shape memory effect, shape memory polymers and FDM were also made. Findings 4D printing has become a burgeoning area in addivitive manufacturing research with many papers being produced within the past 3-5 years. This is especially true for 4D printing using FDM. The key findings from this review show the materials and material composites used for 4D printing with FDM and the limitations with 4D printing with FDM. Research limitations/implications Limitations to this paper are with the availability of papers for review. 4D printing is an emerging area of additive manufacturing research. While FDM is a predominant method of 3D printing, it is not a predominant method for 4D printing. This is because of the limitations of FDM, which can only print with thermoplastics. With the popularity of FDM and the emergence of 4D printing, however, this review paper will provide key resources for reference for users that may be interested in 4D printing and have access to a FDM printer. Practical implications Practically, FDM is the most popular method for 3D printing. Review of 4D printing using FDM will provide a necessary resource for FDM 3D printing users and researchers with a potential avenue for design, printing, training and actuation of active parts and mechanisms. Social implications Continuing with the popularity of FDM among 3D printing methods, a review paper like this can provide an initial and simple step into 4D printing for researchers. From continued research, the potential to engage general audiences becomes more likely, especially a general audience that has FDM printers. An increase in 4D printing could potentially lead to more designs and applications of 4D printed devices in impactful fields, such as biomedical, aerospace and sustainable engineering. Overall, the change and inclusion of technology from 4D printing could have a potential social impact that encourages the design and manufacture of such devices and the treatment of said devices to the public. Originality/value There are other 4D printing review papers available, but this paper is the only one that focuses specifically on FDM. Other review papers provide brief commentary on the different processes of 4D printing including FDM. With the specialization of 4D printing using FDM, a more in-depth commentary results in this paper. This will provide many FDM 3D printing users with additional knowledge that can spur more creative research in 4D printing. Further, this paper can provide the impetus for the practical use of 4D printing in more general and educational settings.
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Zieja, Mariusz, Andrzej Gębura, Andrzej Szelmanowski und Bartłomiej Główczyk. „Non-Invasive Monitoring of the Technical Condition of Power Units Using the FAM-C and FDM-A Electrical Methods“. Sustainability 13, Nr. 23 (01.12.2021): 13329. http://dx.doi.org/10.3390/su132313329.
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This article presents the selected results of analytical and structural work conducted at the Air Force Institute of Technology (pl. ITWL) in the field of building a measuring apparatus for non-invasive monitoring of the technical condition of aircraft power units. Presented innovative FAM-C and FDM-A methods allow for observation of frequency modulation parameters as well as identification and diagnostic classification of particular mechanical subassemblies supplying the on-board generator and thus enable non-invasive monitoring of technical condition of the aircraft power unit and the aircraft propulsion system. The main purpose of this article is to present the measurement apparatus errors that occur in the signal conditioning system in the FAM-C and FDM-A methods. In spite of the fact that the measuring instrument was built on the basis of digital technology and that it uses typical solutions of electronic frequency measurement, due to the specificity of the applied diagnostic method there occur specific measuring errors which are presented in this article.
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Jyothirmayi, M. „Blind Image Seperation Using Forward Difference Method (FDM)“. Signal & Image Processing : An International Journal 2, Nr. 4 (31.12.2011): 121–27. http://dx.doi.org/10.5121/sipij.2011.2410.
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MANDELSHTAM, VLADIMIR A. „ON HARMONIC INVERSION OF CROSS-CORRELATION FUNCTIONS BY THE FILTER DIAGONALIZATION METHOD“. Journal of Theoretical and Computational Chemistry 02, Nr. 04 (Dezember 2003): 497–505. http://dx.doi.org/10.1142/s0219633603000641.
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Harmonic inversion of Chebyshev correlation and cross-correlation functions by the filter diagonalization method (FDM) is one of the most efficient ways to accurately compute the complex spectra of low dimensional quantum molecular systems. This explains the growing popularity of the FDM in the past several years. Some of its most attractive features are the predictable convergence properties and the lack of adjusting parameters. These issues however are often misunderstood and mystified. We discuss the questions relevant to the optimal choices for the FDM parameters, such as the window size and the number of basis functions. We also demonstrate that the cross-correlation approach (using multiple initial states) is significantly more effective than the conventional autocorrelation approach (single initial state) for the common case of a non-uniform eigenvalue distribution.
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Durgun, Ismail. „Sheet metal forming using FDM rapid prototype tool“. Rapid Prototyping Journal 21, Nr. 4 (15.06.2015): 412–22. http://dx.doi.org/10.1108/rpj-01-2014-0003.
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Purpose – The purpose of this paper is to investigate usage of fused deposition modeling (FDM)-based sheet metal tooling for small lot productions as a real case. FDM-based sheet metal tooling was used for stamping prototype parts for two different materials to evaluate dimensional conformance. Design/methodology/approach – The experimental process of data capture used the following steps: sheet metal parts were stamped and optically scanned at every 10th interval for both DC04 and S355MC material. FDM-based upper and lower dies were optically scanned at 1st, 51st and 101st intervals. Dimensional conformance analyses were carried out by using scanned data to evaluate the behavior of FDM dies against DC04 and S355MC materials in terms of geometric deviation. Findings – Satisfactory results were obtained for DC04 material by using FDM-based tooling, and overall deviation was at an acceptable level in terms of production tolerance. S355MC material is harder than DC04 and results were not convenient in terms of tolerance range. Geometric deviation of FDM dies was slightly increased and after the 50th part, increased drastically due to squeezing of FDM layers. Experiments showed that this method can be used for DC04 material and up to 100 parts can be stamped within the tolerance range. Using FDM-based sheet metal tooling, product development phase can be shortened in terms of leading time. Originality/value – This paper presents a study to create an alternative tooling method to shorten product cycle and product development phase by integrating rapid tooling methods to low-volume production.
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Zhang, Dawei, Zhiyong Li, Shengxue Qin und Shanling Han. „Optimization of Vibration Characteristics of Fused Deposition Modeling Color 3D Printer Based on Modal and Power Spectrum Method“. Applied Sciences 9, Nr. 19 (03.10.2019): 4154. http://dx.doi.org/10.3390/app9194154.
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To improve the accuracy of the Fused Deposition Modeling (FDM) color 3D printer in printing color pieces, the vibration characteristics were studied. Firstly, the models of the FDM color 3D printer were qualitatively simplified by mechanics theory to provide theoretical support for dynamic characteristics of the structure, and the finite element modal analysis was performed by the ANSYS (It is an engineering simulation and 3D design software) Workbench to obtain the natural frequency and mode shape displacement of the FDM color 3D printer. Then, the power spectrum of the vibration signal of the previous FDM color 3D printer was measured through frequency domain analysis, and the resonance positions of the 3D printer were obtained by comparing the finite element analysis with experimental analysis. Finally, the design of the color 3D printer was optimized based on the analysis. The results indicate that the optimized scheme can effectively improve the resonance characteristics of the device and reduce the overall modal displacement. The actual experiment of the 3D printer demonstrates that the accuracy of the optimized device has been improved, which has crucial reference significance for the development of the FDM color 3D printer.
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Hu, Huaqing, Ketai He, Tianlin Zhong und Yili Hong. „Fault diagnosis of FDM process based on support vector machine (SVM)“. Rapid Prototyping Journal 26, Nr. 2 (16.10.2019): 330–48. http://dx.doi.org/10.1108/rpj-05-2019-0121.
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Purpose This paper aims to propose a method to diagnose fused deposition modeling (FDM) printing faults caused by the variation of temperature field and establish a fault knowledge base, which helps to study the generation mechanism of FDM printing faults. Design/methodology/approach Based on the Spearman rank correlation analysis, four relative temperature parameters are selected as the input data to train the SVM-based multi-classes classification model, which further serves as a method to diagnose the FDM printing faults. Findings It is found that FDM parts may be in several printing states with the variation of temperature field on the surface of FDM parts. The theoretical dividing lines between different FDM printing states are put forward by traversing all the four-dimensional input parameter combinations. The relationship between the relative mean temperature and the theoretical dividing lines is found to be close and is analyzed qualitatively. Originality/value The multi-classes classification model, embedded in FDM printers as an adviser, can be used to prevent waste products and release much work of labors for monitoring.
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ISHIKAWA, Mikihito, Toshihito OHMI, A. Toshimitsu YOKOBORI Jr. und Masaaki NISHIMURA. „OS1010 The Hydrogen Diffusion Analysis by Finite Element Method and Finite Difference Method“. Proceedings of the Materials and Mechanics Conference 2014 (2014): _OS1010–1_—_OS1010–3_. http://dx.doi.org/10.1299/jsmemm.2014._os1010-1_.
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Bensafi, Mohammed, Belkacem Draoui, Younes Menni und Houari Ameur. „A Thermal Conduction Comparative Study Between the FDM and SPH Methods with A Proposed C++ Home Code“. Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 78, Nr. 1 (01.12.2020): 137–45. http://dx.doi.org/10.37934/arfmts.78.1.137145.
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The heat transfer phenomenon is modeled by the Finite Difference Method (FDM) and the Soothed Particle Hydrodynamic (SPH) approach. The numerical approach under investigation may be used to solve many complex problems of applied mechanics. The Finite Element Method (FEM) is generally used for the Lagrangian description, and the FDM is used for the Eulerian report. However, the SPH method, which is better than other approaches to solve some problems, may be used in many aspects. Numerical details on the SPH method are discussed in this paper, with a focus on its application on the heat equation. A simple two-dimensional heat conduction problem is simulated by using the SPH approximation procedure and the newly constructed quartic smoothing function. Besides, a comparison is made between both techniques. Finally, C++ code is proposed for SPH and FDM methods.
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Rozmus, Magdalena, Piotr Dobrzaniecki, Michał Siegmund und Juan Alfonso Gómez Herrero. „Design with Use of 3D Printing Technology“. Management Systems in Production Engineering 28, Nr. 4 (01.12.2020): 283–91. http://dx.doi.org/10.2478/mspe-2020-0040.
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AbstractDynamic development of 3D printing technology contributes to its wide applicability. FDM (Fused Deposition Method) is the most known and popular 3D printing method due to its availability and affordability. It is also usable in design of technical objects – to verify design concepts with use of 3D printed prototypes. The prototypes are produced at lower cost and shorter time comparing to other manufacturing methods and might be used for a number of purposes depending on designed object’s features they reflect. In the article, usability of 3D printing method FDM for designing of technical objects is verified based on sample functional prototypes. Methodology applied to develop these prototypes and their stand tests are covered. General conclusion is that 3D printed prototypes manufactured with FDM method proved to be useful for verifying new concepts within design processes carried out in KOMAG.
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Wang, Hailong, Haobo Bai, Yan Zhao, Dongsheng Wang, Xiaojing Wang und Shenghua Wang. „The Removal Method of the Blasting Vibration Signal Trend Item and Noise“. Shock and Vibration 2021 (23.10.2021): 1–10. http://dx.doi.org/10.1155/2021/1645380.
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Aiming at the problem that the blasting vibration signal contains trend items and noise interference, a signal processing method based on the Fourier decomposition method (FDM) is introduced. Firstly, based on the FDM theory, the original blasting vibration signal is decomposed to obtain several modal components; then, the dominant component of the signal is filtered according to the dominant frequency of the modal component and its correlation with the original signal; finally, the dominant component is reconstructed to remove the trend item and noise at the same time; spectrum analysis is carried out to verify the effectiveness of the method. The results show that FDM can effectively disperse low-frequency trend items, high-frequency noise, and useful signal information while decomposing signals containing trend terms and noise; compared with the existing common methods, it can more effectively retain the original information, which provides a reference for the trend item and noise removal of similar blasting vibration signals.
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Straszek, Sune P., und Ole F. Pedersen. „Nasal cavity dimensions in guinea pig and rat measured by acoustic rhinometry and fluid-displacement method“. Journal of Applied Physiology 96, Nr. 6 (Juni 2004): 2109–14. http://dx.doi.org/10.1152/japplphysiol.00540.2003.
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The purpose of the study was to measure nasal passageway dimensions in guinea pigs and rats by use of acoustic rhinometry (AR) and by a previously described fluid-displacement method (FDM) (Straszek SP, Taagehoej F, Graff S, and Pedersen OF. J Appl Physiol 95: 635–642, 2003) to investigate the potential of AR in pharmacological research with these animals. We measured the area-distance relationships by AR of nasal cavities postmortem in five guinea pigs (Duncan Hartley, 400 g) and five rats (Wistar, 250 g) by using custom-made equipment scaled for the purpose. Nosepieces were made from plastic pipette tips and either inserted into or glued onto the nostrils. We used liquid perfluorocarbon in the fluid-displacement study, and it was carried out subsequent to the acoustic measurements. We found for guinea pigs that AR measured a mean volume of 98 mm3 (95–100 mm3) (mean and 95% confidence interval) of the first 2 cm of the cavity. FDM measured a mean volume of 146 mm3 (117–175 mm3), meaning that AR only measured 70% (50–90) of the volume by FDM. For rats, the volume from 0 to 2 cm was 58 mm3 (55–61 mm3) by AR and 73 mm3 (60–87 mm3) by FDM, resulting in AR only measuring 83% (66–100%) of volume by FDM (see Table 2 ). We conclude that absolute nasal cavity dimensions are underestimated by AR in guinea pigs and rats. This does not preclude that relative changes may be correctly measured. In vivo trials with AR using rats have not yet been published. The FDM is possibly the most accurate alternative to AR for measurements of the nasal cavity geometry in small laboratory animals, but it can only be used postmortem.
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Deng, Xiaoqiao, Changqing Gu, Bingzheng Xu, Zhuo Li und Xinlei Chen. „Scattering Analysis of Electromagnetic Materials Using Fast Dipole Method Based on Volume Integral Equation“. International Journal of Antennas and Propagation 2013 (2013): 1–6. http://dx.doi.org/10.1155/2013/501413.
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The fast dipole method (FDM) is extended to analyze the scattering of dielectric and magnetic materials by solving the volume integral equation (VIE). The FDM is based on the equivalent dipole method (EDM) and can achieve the separation of the field dipole and source dipole, which reduces the complexity of interactions between two far groups (such as groupiand groupj) fromO(NiNj)toO(Ni+Nj), whereNiandNjare the numbers of dipoles in groupiand groupj, respectively. Targets including left-handed materials (LHMs), which are a kind of dielectric and magnetic materials, are calculated to demonstrate the merits of the FDM. Furthermore, in this study we find that the convergence may become much slower when the targets include LHMs compared with conventional electromagnetic materials. Numerical results about convergence characteristics are presented to show this property.
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Yokus, Asıf, und Hasan Bulut. „On the numerical investigations to the Cahn-Allen equation by using finite difference method“. An International Journal of Optimization and Control: Theories & Applications (IJOCTA) 9, Nr. 1 (15.10.2018): 18–23. http://dx.doi.org/10.11121/ijocta.01.2019.00561.
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In this study, by using the finite difference method (FDM for short) and operators, the discretized Cahn-Allen equation is obtained. New initial condition for the Cahn-Allen equation is introduced, considering the analytical solution given in Application of the modified exponential function method to the Cahn-Allen equation, AIP Conference Proceedings 1798, 020033 [1]. It is shown that the FDM is stable for the usage of the Fourier-Von Neumann technique. Accuracy of the method is analyzed in terms of the errors in and Furthermore, the FDM is treated in order to obtain the numerical results and to construct a table including numerical and exact solutions as well as absolute measuring error. A comparison between the numerical and the exact solutions is supported with two and three dimensional graphics via Wolfram Mathematica 11.
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Kim, Hyo-Jin, Seung-Weon Lim, Mi-Kyung Lee, Sung Won Ju, Suk-Hee Park, Jin-Soo Ahn und Kyung-Gyun Hwang. „Which Three-Dimensional Printing Technology Can Replace Conventional Manual Method of Manufacturing Oral Appliance? A Preliminary Comparative Study of Physical and Mechanical Properties“. Applied Sciences 12, Nr. 1 (23.12.2021): 130. http://dx.doi.org/10.3390/app12010130.
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Three-dimensional printing technology is widely being adopted in the manufacturing of oral appliances. The purpose of this study was to determine the most suitable method of manufacturing oral appliances by comparing the physical and mechanical properties of various 3D printing methods with the conventional method. Experimental groups consisted of six 3D-printed specimens via FDM, two polyjets, SLS, SLA, and DLP, and the milling methods. The control group consisted of an acrylic resin specimen made by the conventional manual method. The water absorption and solubility, color stability, flexural strength, and surface hardness were tested and statistically analyzed. The FDM, SLS, and DLP methods exhibited comparable water absorption and solubility with the control group, and only the SLA method exhibited significantly higher water solubility than the control group. In terms of the color stability, only the milling method met the requirements of the allowable clinical range. The FDM, SLA, and DLP methods exhibited comparable flexural strength with the control group. The surface hardness of the PJ-2, DLP, and milling methods was acceptable for replacing conventional manual method. Therefore, the most suitable method of manufacturing oral appliances among the experimental groups was the DLP method in terms of its water absorption and solubility, flexural strength, and surface hardness.
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Shao, Dongguo, Haidong Yang, Yi Xiao und Biyu Liu. „Water quality model parameter identification of an open channel in a long distance water transfer project based on finite difference, difference evolution and Monte Carlo“. Water Science and Technology 69, Nr. 3 (20.11.2013): 587–94. http://dx.doi.org/10.2166/wst.2013.753.
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A new method is proposed based on the finite difference method (FDM), differential evolution algorithm and Markov Chain Monte Carlo (MCMC) simulation to identify water quality model parameters of an open channel in a long distance water transfer project. Firstly, this parameter identification problem is considered as a Bayesian estimation problem and the forward numerical model is solved by FDM, and the posterior probability density function of the parameters is deduced. Then these parameters are estimated using a sampling method with differential evolution algorithm and MCMC simulation. Finally this proposed method is compared with FDM–MCMC by a twin experiment. The results show that the proposed method can be used to identify water quality model parameters of an open channel in a long distance water transfer project under different scenarios better with fewer iterations, higher reliability and anti-noise capability compared with FDM–MCMC. Therefore, it provides a new idea and method to solve the traceability problem in sudden water pollution accidents.
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Tang, Yingying, Yingshuai Li, Yanwei Niu, Hong Chen und Huang Pingming. „Finite Difference Method in Stress Analysis of Anchorage Zone of Highway Extradosed Cable Stayed Bridge“. MATEC Web of Conferences 206 (2018): 01007. http://dx.doi.org/10.1051/matecconf/201820601007.
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With the development and wide application of extradosed cable stayed bridge, an effective method is needed for simulation of the stress distribution in anchorage zone, which plays a vital role in transferring force from the cable to the pylon and diverting the cable direction. Based on the Finite Difference Method (FDM), an efficient and practical method of stress filed simulation was presented in the paper. First, a plane finite element model was established using ABAQUS, to determine the boundary condition for FDM. Based on this, FDM was used to simulate the stress distribution of the concrete in the anchorage zone. Finally, on the simulation result was calculated and in comparison with finite element model result. It has been found that: The vertical compressive stress of concrete in the anchorage zone gradually reduces from the middle to the two sides, and the stress assumes double peak type in transverse. Compared with the finite element solutions, the approximate solution simulated by FDM improve the computational efficiency with certain accuracy keeping, except the loading area. In vertical orientation, the concrete in the place of H (the width of the pylon) from cable force acting position is in a state of uniform stress.
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Jennings, Keith, und Patrick J. Naughton. „Similitude Conditions Modeling Geosynthetic-Reinforced Piled Embankments Using FEM and FDM Techniques“. ISRN Civil Engineering 2012 (08.05.2012): 1–16. http://dx.doi.org/10.5402/2012/251726.
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The numerical modelling of geosynthetic-reinforced piled embankments using both the finite element method (FEM) and finite difference method (FDM) are compared. Plaxis 2D (FEM) was utilized to replicate FLAC (FDM) analysis originally presented by Han and Gabr on a unit cell axisymmetric model within a geosynthetic reinforced piled embankment (GRPE). The FEM and FED techniques were found to be in reasonable agreement, in both characteristic trend and absolute value. FEM consistently replicated the FDM outputs for deformational, loading, and load transfer mechanism (soil arching) response within the reinforced piled embankment structure with a reasonable degree of accuracy. However the FDM approach was found to give a slightly higher reinforcement tension and stress concentration but lower reinforcement strain at the pile cap than FEM, which was attributed to the greater discretize of the model geometry in the FDM than in FEM.
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Çevik, Ümit, und Menderes Kam. „A Review Study on Mechanical Properties of Obtained Products by FDM Method and Metal/Polymer Composite Filament Production“. Journal of Nanomaterials 2020 (20.11.2020): 1–9. http://dx.doi.org/10.1155/2020/6187149.
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In addition to traditional manufacturing methods, Additive Manufacturing (AM) has become a widespread production technique used in the industry. The Fused Deposition Modeling (FDM) method is one of the most known and widely used additive manufacturing techniques. Due to the fact that polymer-based materials used as depositing materials by the FDM method in printing of parts have insufficient mechanical properties, the technique generally has limited application areas such as model making and prototyping. With the development of polymer-based materials with improved mechanical properties, this technique can be preferred in wider application areas. In this context, analysis of the mechanical properties of the products has an important role in the production method with FDM. This study investigated the mechanical properties of the products obtained by metal/polymer composite filament production and FDM method in detail. It was reviewed current literature on the production of metal/polymer composite filaments with better mechanical properties than filaments compatible with three-dimensional (3D) printers. As a result, it was found that by adding reinforcements of composites in various proportions, products with high mechanical properties can be obtained. Thus, it was predicted that the composite products obtained in this way can be used in wider application areas.
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Yuan, Shi Hua, Ding Hua Liu und Chao Wei. „Numerical Method for Pressure Distribution Calculation on Spherical Distribution Pair of IHT“. Applied Mechanics and Materials 52-54 (März 2011): 1427–32. http://dx.doi.org/10.4028/www.scientific.net/amm.52-54.1427.
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To calculate the pressure distribution of oil film on spherical port plate of Innas hydraulic transformer (IHT), finite difference method (FDM) based on boundary fitted coordinate (BFC) technique is presented. Spherical curvilinear grid system was obtained with a coincident boundary of irregular physical area. The flux conservation form of Reynolds’ equation was applied as control equation. By FDM, the thickness distribution and pressure distribution of distribution pair were calculated. It shows that BFC transformation method is advantaged to closely simulate the physical domain with complex geometrical boundaries.
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Li, Hong Bin, Ying Tian, Peng Lin Li, Lei Zhang und Yu Long Wang. „The Optimization of Modeling Orientation in FDM“. Key Engineering Materials 693 (Mai 2016): 1163–68. http://dx.doi.org/10.4028/www.scientific.net/kem.693.1163.
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This paper introduces an optimization algorithm for rapid prototyping. In the optimization algorithm, several important influencing factors are considered, such as the molding direction, the extrusion speed, and layer thickness, etc. And the velocity and effectiveness of the method are validated experimentally. The algorithm can get the best molding direction and maximum hierarchical layer thickness. The method is comprehensive, overcoming the problems of current optimization methods for one-side shortcomings, and can make guidance for the adaptive slicing and path planning.
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Gholaminejad, Ahmadreza, Ahmad Mahboubi und Ali Noorzad. „Combined DEM-FDM modelling of encased stone column“. E3S Web of Conferences 92 (2019): 16012. http://dx.doi.org/10.1051/e3sconf/20199216012.
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Combination of the continuum-based numerical methods and the discrete element method (DEM) could be a powerful way of simulating complex problems. This approach benefits from the capabilities of both methods. The main feature of the discrete element method is that the soil grains are considered as individual particles without need to impose any behaviour law in modelling the medium. The limitation of this method is, however, its high computational demand. In continuum based methods, on the other hand, it is impossible to trace micro scale phenomena. According to these facts, combining continuum and discrete methods is an optimal way in approaching geotechnical problems which deal with granular soils. In this approach, the coarse grain zone (medium) is modelled using DEM and the surrounding media are modelled using the continuum methods. Stone columns that are widely used for improving and/or increasing the strength of weak soils could be modelled using this type of coupled simulation. The Coarse aggregates present in the stone column make it appropriate for the coupled modelling. In this paper, the ordinary and encased stone columns have been simulated by combining 2D DEM and finite difference method (FDM). Clump technique was employed to achieve the interlocking of aggregate particles in DEM, and the surrounding cohesive soil was modelled using FDM. The obtained results were validated by the reported experimental results in the literature, indicating that the coupled DEM-FDM method is a robust way to simulate stone columns.
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Nguyen, Thanh Nam, Tuyen Vo, Minh Tam Nguyen und Tu Nguyen Thanh. „A Research of Design the Control System of 3D Printer by Fused Deposition Modeling (FDM) Technology“. Applied Mechanics and Materials 902 (September 2020): 65–70. http://dx.doi.org/10.4028/www.scientific.net/amm.902.65.
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Nowadays, 3D printing technology or Additive Manufacture (AM) is becoming more and more popular in industries and life. Additive Material technology is a technology of linking or crystallizing materials under the control of a computer to create three-dimensional details. Additive Manufacture Technology currently consists of many different methods, in which the method of extruding molten materials through the nozzle called Fused Deposition Modeling (FDM) is the most popular. Almost all 3D printer machines that use this method are now very popular in the market, with the ability to work suitable for many types of objects, from individual scale to company one. However, the design and manufacture of these machines are carried out according to traditional methods, with many limitations. The paper presents an application of selective design method for FDM technology analysis results according to the module in [5] to implement the control system design of FDM to reduce costs and improve the reliability of the product.
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Christou, Petros, Antonis Michael und Miltiades Elliotis. „Implementing slack cables in the force density method“. Engineering Computations 31, Nr. 5 (01.07.2014): 1011–30. http://dx.doi.org/10.1108/ec-03-2012-0054.
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Purpose – The purpose of this paper is to present a solution strategy for the analysis of cable networks which includes an extension to the force density method (FDM) in an attempt to support cable elements when they become slack. The ability to handle slack cable elements in the analysis is particularly important especially in cases where the original cable lengths are predefined, i.e. the cable structure has already been constructed, and there is a need for further analysis to account for additional loading such as wind. The solution strategy is implemented in a software application. Design/methodology/approach – The development of the software required the implementation of the FDM for the analysis of cable networks and its extension to handle constraints. The implemented constraints included the ability to preserve the length in the stressed or the unstressed state of predefined cable elements. In addition, cable statics are incorporated with the development of the cable equation and its modification to be able to be handled by the FDM . Findings – The implementation of the solution strategy is presented through examples using the software which has been developed for these purposes. Originality/value – The results suggest that for cable networks spanning large distances or cable elements with considerable self-weight the neglect of the cable slackening effects is not always conservative.
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Wei, Shuaishuai, Kun Wang, Huan Zhang, Junming Zhang, Jincheng Wei, Wenyang Han und Lei Niu. „A Permeability Estimation Method Based on Elliptical Pore Approximation“. Water 13, Nr. 22 (20.11.2021): 3290. http://dx.doi.org/10.3390/w13223290.
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Digital rock images may capture more detailed pore structure than the traditional laboratory methods. No explicit function can correlate permeability accurately for flow within the pore space. This has motivated researchers to predict permeability through the application of numerical techniques, e.g., using the finite difference method (FDM). However, in order to get better permeability calculation results, the grid refinement was needed for the traditional FDM and the accuracy of the traditional method decreased in pores with elongated cross sections. The goal of this study is to develop an improved FDM (IFDM) to calculate the permeabilities of digital rock images with complex pore space. An elliptical pore approximation method is invoked to describe the complex pore space. The permeabilities of four types of idealized porous media are calculated by IFDM. The calculated results are in sound agreement with the analytical solutions or semi-empirical solutions. What’s more, the permeabilities of the digital rock images after grid coarsening are calculated by IFDM in three orthogonal directions. These results are compared with the previously validated lattice-Boltzmann method (LBM), which indicates that the predicted permeabilities calculated by IFDM usually agree with permeabilities calculated by LBM. We conclude that the presented IFDM is suitable for complex pore space.
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Li, Feng, Zhonghua Yu und Zhensheng Yang. „Failure characterization of PLA parts fabricated by fused deposition modeling using acoustic emission“. Rapid Prototyping Journal 26, Nr. 7 (13.06.2020): 1177–82. http://dx.doi.org/10.1108/rpj-09-2019-0247.
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Purpose This paper aims to focus on investigating the failure mode of fused deposition modeling (FDM) fabricated parts by using acoustic emission (AE) technique. Design/methodology/approach Considering the special prototyping way of FDM, the failure modes of FDM-fabricated parts were investigated experimentally. One test was carried out and the other two describe what has been observed on this basis. Acoustic emissions are obtained during the tensile process. AE features of peak frequency, energy and amplitude are extracted and preliminarily analyzed. Then, the unsupervised clustering method of k-means is applied to explore the relationship between the failure modes and the AE signals. Findings Failure modes of filament debonding and breakage can be successfully recognized by the pattern recognition technique of k-means. Practical implications The results obtained can help us understand the failure process of FDM printed parts. This will provide an available monitoring method in the application of FDM-fabricated parts. Originality/value This paper has investigated and characterized the failure modes of FDM fabricated parts for the first time.
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Gębura, Andrzej, und Włodzimierz Markiewicz. „Presentations in FAM-C And FDM-A Methods and Some Problems of a Signals Theory“. Solid State Phenomena 147-149 (Januar 2009): 504–11. http://dx.doi.org/10.4028/www.scientific.net/ssp.147-149.504.
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The FDM-A diagnostic method [2, 4] based on a frequency modulation measurement of a pulsation component as well as the FAM-C method of an alternating current frequency have been elaborated in Air Force Institute of Technology. These methods to define a level of an assembly abrasive wear as well as its localization during a normal work of a power unit. A diagnostic signal is derived from onboard generators or alternators. Each damaged part of the generator’s or alternator’s power unit is a vibration generator or modulator. The vibration is turned into oscillation in onboard generators or alternators. After many years of the FAM-C and FDM-A methods’ using it is possible to localize and define value of many faults of power units: a coupling eccentricity, a shaft skew, extender longitudinal clearances of turbine engine’s rotor assembly, a frictional resistance of bearings, a smoothness of bearing’s rolling and a bearing cage, a break of rolling bearing’s separator, a misalignment of a rotor assembly’s support, etc. In FAM-C and FDM-A methods two kinds of presentations are used: first a presentation as characteristic patterns (analogous to Fourier spectrum lines but providing to observe periodical and stochastical phenomena) as well as the presentation of the frequency versus time. From the point of view of authors in many cases they are similar to presentations known from a theory of a radio signals transmission. It is possible to find carrier wale and side spectrum lines, beats caused by summation of two signals with approximate frequencies as well as many others. If analogy is so univocal, it is possible to use many systems and dependences used in telecommunication. For example: coherence demodulation (synchronous), which authors intend to use for separation characteristic patterns of two different mechanical assemblies with approximate vibration frequencies. At the end there are presented authors’ considerations, related to superposition of signals and beats as well as reflection of these phenomena in observed power units.
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Yan, Wu Jian, Yan Bin Wang und Yu Cheng Shi. „Simulation of the Seismic Response of 2D Sedimentary Basin with Hybrid PSM/FDM Method“. Advanced Materials Research 594-597 (November 2012): 1840–48. http://dx.doi.org/10.4028/www.scientific.net/amr.594-597.1840.
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Abstract: In this paper, we simulated two-dimension numerical on the strong ground motion in Lanzhou basin through the hybrid scheme based on the pseudospectral method (PSM) and finite difference method (FDM). We base on a focal of 20 km deep and a profile of 5 layers is used as model to analyze the site response and the peak displacement of strong ground motion. The results show that the hybrid PSM/FDM method for seismic wavefield simulation combines with advantages of PSM and FDM and makes up for the disadvantage of them, so this method can process well the calculation of the discontinuous medium surface, then the calculation accuracy is similar to PSM. Through the wavefield simulation it is known that the peak ground displacement (PGD) of the vertical is larger and the influence of surface wave at the basin edge is more obvious than the horizontal.
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Kaczmarzyk, Marcin, Marcin Gawronski und Grzegorz Piatkowski. „Application of Finite Difference Method for determining lunar regolith diurnal temperature distribution“. E3S Web of Conferences 49 (2018): 00052. http://dx.doi.org/10.1051/e3sconf/20184900052.
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This study was performed in order to verify viability of using finite difference method and proposed simple astrometrical model for modelling heat transfer in lunar regolith. The concept was examined by developing FD model of heat flow for upper 0,9 m of lunar regolith, and comparing obtained results with in situ measurements provided by Apollo 15 and 17 heat flow experiments. The model was based on FDM approximation of Fourier’s law for one dimensional transient heat flow. Both constant and temperature-dependent thermophysical properties of lunar regolith were obtained from in situ measurements. Thermal boundary conditions were assumed on in situ measurements and on remote sensing based analytical model. In order to approximate Sun's position at lunar sky, simple analytical astrometric model of lunar rotation was developed. Matlab 2012a was used to conduct the calculations. Stable solutions were obtained for latitudes between 0 and 80°. Satisfactory agreement between Apollo 15 and 17 in situ measurements and FDM modelling was observed. A conclusion was reached, that both FDM and proposed astrometrical model are to be successfully applied for modelling heat transfer in lunar regolith.
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Yunus, Mohammed, und Mohammad S. Alsoufi. „Effect of raster inclinations and part positions on mechanical properties, surface roughness and manufacturing price of printed parts produced by fused deposition method“. Journal of Mechanical Engineering and Sciences 14, Nr. 4 (17.12.2020): 7416–23. http://dx.doi.org/10.15282/jmes.14.4.2020.10.0584.
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Additive manufacturing (AM) technology has the ability to produce parts or products using data from 3D CAD models based on adding material. Fused deposition modeling (FDM) is among the most popular AM technologies wherein the plastic materials like acrylonitrile-butadiene-styrene filaments get added in the form of semi-molten plastic layers from bottom to top to produce the final product. Besides, the merits of using the FDM process, it faces challenges related to strength, dimensional accuracy, surface finish, and so on. The mechanical, tribological, and surface finish of functional parts is an essential consideration in FDM. In this work, the role of process parameters such as the part positions and raster inclinations involved in the manufacturing of parts by FDM has been evaluated experimentally to obtain the desired properties for reducing production time, the quantity of supporting material, and overall cost including maintenance costs. The study revealed that part position is a more significant parameter than the raster inclinations on the surface roughness and mechanical properties of the FDM parts. It also concludes with the proper values of part positions and raster inclinations for achieving optimal mechanical properties, roughness, and manufacturing costs to withstand operating loading conditions.
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Quan Jiang und M. Kavehrad. „A frequency calibration method for multilocation optical FDM networks“. IEEE Photonics Technology Letters 5, Nr. 10 (Oktober 1993): 1253–56. http://dx.doi.org/10.1109/68.248445.
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Jaworska, Irena, und Janusz Orkisz. „Higher order multipoint method – from Collatz to meshless FDM“. Engineering Analysis with Boundary Elements 50 (Januar 2015): 341–51. http://dx.doi.org/10.1016/j.enganabound.2014.09.007.
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Taniguchi, Hideo, und Jiro Oi. „Novel Method to Drive New High Temp FDM Hotend“. NIP & Digital Fabrication Conference 36, Nr. 1 (01.10.2020): 22–25. http://dx.doi.org/10.2352/issn.2169-4451.2020.36.22.
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Choi, S. J., F. X. Giraldo, J. Kim und S. Shin. „Verification of a non-hydrostatic dynamical core using the horizontal spectral element method and vertical finite difference method: 2-D aspects“. Geoscientific Model Development 7, Nr. 6 (19.11.2014): 2717–31. http://dx.doi.org/10.5194/gmd-7-2717-2014.
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Abstract. The non-hydrostatic (NH) compressible Euler equations for dry atmosphere were solved in a simplified two-dimensional (2-D) slice framework employing a spectral element method (SEM) for the horizontal discretization and a finite difference method (FDM) for the vertical discretization. By using horizontal SEM, which decomposes the physical domain into smaller pieces with a small communication stencil, a high level of scalability can be achieved. By using vertical FDM, an easy method for coupling the dynamics and existing physics packages can be provided. The SEM uses high-order nodal basis functions associated with Lagrange polynomials based on Gauss–Lobatto–Legendre (GLL) quadrature points. The FDM employs a third-order upwind-biased scheme for the vertical flux terms and a centered finite difference scheme for the vertical derivative and integral terms. For temporal integration, a time-split, third-order Runge–Kutta (RK3) integration technique was applied. The Euler equations that were used here are in flux form based on the hydrostatic pressure vertical coordinate. The equations are the same as those used in the Weather Research and Forecasting (WRF) model, but a hybrid sigma–pressure vertical coordinate was implemented in this model. We validated the model by conducting the widely used standard tests: linear hydrostatic mountain wave, tracer advection, and gravity wave over the Schär-type mountain, as well as density current, inertia–gravity wave, and rising thermal bubble. The results from these tests demonstrated that the model using the horizontal SEM and the vertical FDM is accurate and robust provided sufficient diffusion is applied. The results with various horizontal resolutions also showed convergence of second-order accuracy due to the accuracy of the time integration scheme and that of the vertical direction, although high-order basis functions were used in the horizontal. By using the 2-D slice model, we effectively showed that the combined spatial discretization method of the spectral element and finite difference methods in the horizontal and vertical directions, respectively, offers a viable method for development of an NH dynamical core.
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Straszek, Sune P., Finn Taagehøj, Søren Graff und Ole F. Pedersen. „Acoustic rhinometry in dog and cat compared with a fluid-displacement method and magnetic resonance imaging“. Journal of Applied Physiology 95, Nr. 2 (August 2003): 635–42. http://dx.doi.org/10.1152/japplphysiol.01105.2002.
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An increasing number of studies have used acoustic rhinometry (AR) for study of pharmacological interventions on nasal cavity dimensions in dogs and cats, but there have been no attempts to validate AR in these species. This is done in the present study. We compared area-distance relationships of nasal cavities from five decapitated dogs (3.5–41 kg) and cats (3.8–6 kg). AR was compared with magnetic resonance (MR) imaging and a fluid-displacement method (FDM) using perfluorocarbon. AR measured 88% (98–79%) (mean and 95% confidence interval) of nasal cavity volume in dogs determined by FDM and 71% (83–59%) in cats. AR markedly underestimated nasal cavity dimensions when minimum areas were below 0.1 cm2 in dogs and 0.05 cm2 in cats. AR underestimation increased with the severity of the constriction and with distance. Cross-sectional areas in the deeper parts of the cavity measured 76% (99–54%) of FDM in dogs and 52% (66–39%) in cats. AR agreed well with MR, especially in the deeper part of the cavity. MR images showed that the nasal cavities had a very complex structure not expected to be reproduced by AR. MR could not be considered a “gold standard” because definition of the cross-sectional area of the lumen depended critically on subjective choices. FDM produced repeatable measurements and possibly offers the most adequate reference in future evaluation of AR. AR underestimated what we believed were the most correct cross-sectional areas determined by FDM, especially in the deeper part of the dog and cat nasal cavities. Despite these difficulties, AR has been shown to be useful to describe qualitative changes in cross-sectional area.
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Cheng, Dawei, Wenke Wang, Xi Chen und Zaiyong Zhang. „Finite Analytic Method for One-Dimensional Nonlinear Consolidation under Time-Dependent Loading“. Shock and Vibration 2017 (2017): 1–12. http://dx.doi.org/10.1155/2017/4071268.
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For one-dimensional (1D) nonlinear consolidation, the governing partial differential equation is nonlinear. This paper develops the finite analytic method (FAM) to simulate 1D nonlinear consolidation under different time-dependent loading and initial conditions. To achieve this, the assumption of constant initial effective stress is not considered and the governing partial differential equation is transformed into the diffusion equation. Then, the finite analytic implicit scheme is established. The convergence and stability of finite analytic numerical scheme are proven by a rigorous mathematical analysis. In addition, the paper obtains three corrected semianalytical solutions undergoing suddenly imposed constant loading, single ramp loading, and trapezoidal cyclic loading, respectively. Comparisons of the results of FAM with the three semianalytical solutions and the result of FDM, respectively, show that the FAM can obtain stable and accurate numerical solutions and ensure the convergence of spatial discretization for 1D nonlinear consolidation.
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Płaczek, Dominika. „Adhesion between the bed and component manufactured in FDM technology using selected types of intermediary materials“. MATEC Web of Conferences 290 (2019): 01012. http://dx.doi.org/10.1051/matecconf/201929001012.
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FDM technology (Fused Deposition Modeling) is a popular form of additive manufacturing of elements. The development of this technology is related to the need of achieving high accuracy of products and shortening the time of manufacturing. Despite the through of advantages, FDM technology involves several technological problems. One of them is the phenomenon of detaching created element from the bed of the device as a result of processing shrinkage. One of the methods of increasing the adhesion of elements to the bed is the use of glued intermediate materials. Among the available options, there are tapes dedicated to FDM technology, such as adhesive pads. In addition, they are used Kapton and cheaper, cellulose tapes. The article presents the method of testing the adhesion force between element and bed of the device producing in FDM technology and obtained values for the use of various types of intermediary materials. The specimens were made of one of the most commonly used material - PLA. A glass bed was used for the test. The results were compared with values of adhesion force for elements produced on a smooth, uncoated bed. The method and research results allow to compare and select the appropriate method based on empirically determined values.