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1
Fiedler, Josef, und Tomáš Koudelka. „Nonlinear Behaviour of Concrete Foundation Slab“. Applied Mechanics and Materials 821 (Januar 2016): 495–502. http://dx.doi.org/10.4028/www.scientific.net/amm.821.495.
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A layered model is used for nonlinear analysis of a foundation concrete slab. Calculation is performed using interaction with elastic Winkler-Pasternak subsoil model and considering plastic yielding of slab layers. Two Drucker-Prager yield criterions define a nonlinear material model for concrete. Computation is done by the SIFEL solver using the Finite Element Method.
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Liao, Ming Cheng, Zhen Ya Xiao und Yao Qing Gong. „Soil-Structure Interactions of Tube-in-Tube System of Tall Buildings Based on ODE Solver“. Applied Mechanics and Materials 204-208 (Oktober 2012): 1118–24. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.1118.
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A new analytical method for the analysis of interactions between the superstructure and foundation and foundation soil of a tall building is formulated. The computational model of a structural system and its foundation are simplified equivalently and continuously into a three-dimensional model, a combination of thin-walled tubes on a semi-infinite elastic subgrade. The various stiffness coefficients for evaluating elastic strain energy stored in foundation soil are as well derived by using the principle of energy equivalency. Some satisfying conclusions are obtained by the interaction analysis for the tube-in-tube structural system adopted by Guangdong Guomao Building.
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Svinicki, M. D. „A theoretical foundation for discovery learning.“ Advances in Physiology Education 275, Nr. 6 (Dezember 1998): S4. http://dx.doi.org/10.1152/advances.1998.275.6.s4.
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The processes of discovery learning are well grounded in current theories of learning. This article describes how cognitive learning theory supports the components of the discovery learning model. Three main characteristics of discovery learning that relate it to cognitive theory are 1) an emphasis on active learning, 2) the development of meaningful learning, and 3) the capacity to change attitudes and values toward the subject and the self as problem solver.
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Arboleda Molina, Orlando, und Steven Sotelo. „Construcción de aplicativos de programación por restricciones en Microsoft Solver Foundation y Windows Azure“. Scientia et technica 21, Nr. 4 (30.12.2016): 336. http://dx.doi.org/10.22517/23447214.11571.
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A nivel empresarial y académico se requiere la construcción de aplicativos para resolver problemas de optimización de restricciones, y que estos puedan ser ofrecidos como servicios en la nube. En el presente artículo se modela y resuelve un problema de optimización de restricciones, correspondiente al problema de transporte, usando para su modelamiento y posterior publicación como servicio en la nube, solo tecnología .Net, aplicable a problemas computacionalmente complejos de restricciones, usando Microsoft Solver Foundation que permite la construcción de poderosos aplicativos genéricos de pocas líneas de código, los cuales pueden ser fácilmente publicados como servicios web en Windows Azure.
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Lohar, Hareram, Anirban Mitra und Sarmila Sahoo. „Mode switching phenomenon in geometrically nonlinear free vibration analysis of in-plane inhomogeneous plates on elastic foundation“. Curved and Layered Structures 5, Nr. 1 (01.07.2018): 156–79. http://dx.doi.org/10.1515/cls-2018-0012.
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Abstract Effect of geometric nonlinearity onfree vibration behaviour of a non-uniform in-plane inhomogeneousplate on elastic foundation is carried out with an emphasis on mode switching phenomenon. The formulation is semianalytic displacement based and it is carried out in two distinct steps. First, the static problem is solved to find out the unknown displacement field by using minimum total potential energy principle. Secondly, subsequent dynamic problem is set up as an eigenvalue problem on the basis of the known displacement field. The governing set of equations in dynamic problem is obtained by using Hamilton’s principle. In static analysis, unknown co-efficient of the governing equations are solved using an iterative method, which is direct substitution with relaxation method. The dynamic problem is solved with the help of intrinsic Matlab solver. The results of the present method are validated with existing data. Backbone curve corresponding to different combinations of systemparameters are presented in non-dimensional plane.Mode switching is observed to occur in certain specific situation. The linear and nonlinear mode shapes are also furnished to support the presence of switching phenomenon.
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Saleem, Ayhan H., und Jowhar R. Mohammad. „Simulation of Mosul Dam Break Using Finite Volume Method“. Polytechnic Journal 10, Nr. 2 (30.12.2020): 10–20. http://dx.doi.org/10.25156/ptj.v10n2y2020.pp10-20.
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Mosul dam is an earth-fill embankment located north of Iraq on the Tigris River forming a reservoir with 11.11 km3 water storage capacity which is the largest dam in the country. The dam is built on a rock bed foundation, in which the dissolution process is dynamic in the zone where gypsum and anhydrite layers present. During the construction development seepage locations were found in the dam foundation and the grouting process is in progress until now to control this problem. Therefore, the possibility of the Mosul dam break is highlighted by previous studies. In this research, a FORTRAN code based on the finite volume method is modified to solve the two-dimensional shallow water equations and simulating the Mosul dam break. The computational domain discretized using unstructured triangular mesh. The solver applied Harten lax van leer with contact (HLLC) wave approximate Riemann solver to calculate the cell interface fluxes, and the semi-implicit scheme employed to solve the friction source term. The numerical scheme applied to two benchmark test cases, and the results showed that the presented model was robust and accurate especially in handling wet/dry beds, mixed flow regimes, discontinuities, negative water depths, and complex topography. The results of this study demonstrate that flood waves may reach the center of Mosul city in < 6 h and water depth may rise to 34 m after 7 h of Mosul dam breaking. Finally, the simulation results of the Mosul dam break were used to prepare an emergency action plan.
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Mihami, Fatima-zahra, und Volker Roeber. „AN EFFICIENT AND ROBUST GPGPU-BASED SHALLOW WATER MODEL“. Coastal Engineering Proceedings, Nr. 36v (28.12.2020): 47. http://dx.doi.org/10.9753/icce.v36v.waves.47.
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We present an efficient and robust numerical model for the solution of the Shallow Water Equations with the objective to develop the numerical foundation for an advanced free surface flow solver. The numerical solution is based on an explicit Finite Volume scheme on a staggered grid to ensure the conservation of mass and momentum across flow discontinuities and wet-dry transitions. This leads to an accurate numerical solution at low computational cost without the need for Riemann solvers. The efficiency of the lean numerical structure is further optimized through a CUDA-GPU implementation.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/xMnK_r7Tj1Q
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Sadeghi, J., A. Khajehdezfuly, M. Esmaeili und D. Poorveis. „An Efficient Algorithm for Nonlinear Analysis of Vehicle/Track Interaction Problems“. International Journal of Structural Stability and Dynamics 16, Nr. 08 (25.08.2016): 1550040. http://dx.doi.org/10.1142/s0219455415500406.
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In this paper, a new algorithm for solving the vehicle/track dynamic interaction problem is developed, aimed at reducing the computational cost. The algorithm called Advanced Solver Algorithm (ASA) uses the full Newton–Raphson incremental-iterative method in conjunction with the Newmark integration scheme to solve the equilibrium equations of the coupled vehicle/track system in time domain. Considering the track as a beam resting on a viscoelastic foundation and each vehicle as a wagon with ten degrees of freedom, the governing differential equations of motion of the vehicle/track system were derived. The wheel/rail contact was considered as a nonlinear Hertz spring and consequently the vehicle/track nonlinear dynamic interaction problem was solved. A comparison between the results of the ASA and those of the most advanced algorithm available was made to evaluate the efficiency of the ASA. It is confirmed that using the ASA can result in 40–70 % of reduction in computational cost.
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Yang, Guang Jun, Jian Jun Liu und Jing Sun. „Computational Aeroacoustic Simulation of Landing Gear“. Applied Mechanics and Materials 421 (September 2013): 110–15. http://dx.doi.org/10.4028/www.scientific.net/amm.421.110.
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RANS / NLAS numerical simulation method is adopted in this paper to carry out study on the aerodynamic noise analysis of basic landing gear configuration. Reynolds average N-S equation is solved with nonlinear turbulence model to establish the landing gear initial flow field, based on which, the NLAS (nonlinear acoustic solver) processed the turbulence fluctuation reconstruction to obtain the near-field acoustic characteristics of landing gear. Combined with the flow characteristics and the associated noise spectrum analysis, aerodynamic noise characteristics of landing gear are achieved. The work in this paper can provide useful research foundation on the following noise reduction design of landing gear.
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Xie, Xiang Dong, Xuan Wang und Li Qin. „The Influence of Static Response of Super Tall Building Mega-Frame Structure Caused by Changes of Frame Rigidities“. Applied Mechanics and Materials 166-169 (Mai 2012): 277–81. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.277.
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The superstructure and its foundation of a super tall building mega-frame structure are simplified equivalently and continuously to a stiffened-thin-wall tube on semi-infinite elastic subgrade. And the influences of static response on super tall building mega-frame structure caused by changes of frame rigidity are computed and analyzed with the three-dimensional model by semi-analytical approach based on ODE(Ordinary Differential Equation) Solver, considering the interactions of subgrade, foundation and superstructure. Then some valuable conclusions are obtained through analyzing the reasonable results of the numerical example.
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Tran, H. H. T., K. C. Toh und K. K. Phoon. „Preconditioned IDR(s) iterative solver for non-symmetric linear system associated with FEM analysis of shallow foundation“. International Journal for Numerical and Analytical Methods in Geomechanics 37, Nr. 17 (04.02.2013): 2972–86. http://dx.doi.org/10.1002/nag.2171.
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Azhim, Abdul, und Widjojo A. Prakoso. „Construction cost optimization of shallow foundation for sand soil in Indonesia“. MATEC Web of Conferences 270 (2019): 05005. http://dx.doi.org/10.1051/matecconf/201927005005.
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In designing foundation, there are three fundamental requirements namely: ultimate limit state (ULS), serviceability limit state (SLS), and economics. Generally, the ULS and SLS are the focus of the design process, while the cost factors are not explicitly considered. This paper deals with the three requirements with the minimum construction cost as the controlling objective. A wide range of sand density conditions are considered, while the typical ULS and SLS design checks available in the literature are employed. The optimization tool used is the Solver add-in function available in MS-Excel™. The effects of different construction cost structures in four Indonesia's provinces are examined in this paper. The purpose of this research is to be able in designing the shallow foundation with 3 aspects consideration at once, namely ULS, SLS and economic. On the other hand, this research is to analyse the sensitivity's factor which influence the design, namely work unit price, soil properties and design's requirements.
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Ray, Richard Paul. „An Optimized Elasto-Plastic Subgrade Reaction For Modeling The Response Of A Nonlinear Foundation For A Structural Analysis“. Slovak Journal of Civil Engineering 23, Nr. 3 (01.09.2015): 21–27. http://dx.doi.org/10.1515/sjce-2015-0014.
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Abstract Geotechnical and structural engineers are faced with a difficult task when their designs interact with each other. For complex projects, this is more the norm than the exception. In order to help bridge that gap, a method for modeling the behavior of a foundation using a simple elasto-plastic subgrade reaction was developed. The method uses an optimization technique to position 4-6 springs along a pile foundation to produce similar load deflection characteristics that were modeled by more sophisticated geotechnical finite element software. The methodology uses an Excel spreadsheet for accepting user input and delivering an optimized subgrade spring stiffness, yield, and position along the pile. In this way, the behavior developed from the geotechnical software can be transferred to the structural analysis software. The optimization is achieved through the solver add-in within Excel. Additionally, a beam on a nonlinear elastic foundation model is used to compute deflections of the optimized subgrade reaction configuration.
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Do, Nhon V., Hien D. Nguyen und Ali Selamat. „Knowledge-Based Model of Expert Systems Using Rela-Model“. International Journal of Software Engineering and Knowledge Engineering 28, Nr. 08 (August 2018): 1047–90. http://dx.doi.org/10.1142/s0218194018500304.
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Knowledge about relations plays a crucial role in human’s knowledge. Different methods for representing this type of knowledge have been proposed. However, due to the lack of theoretical foundations, these methods cannot guarantee criteria in knowledge representation such as formality, universality, usability and practicality. They are not adequate to represent the knowledge domains in practice which have many components. Based on formal ontology approach, a knowledge model about relations, called Rela-model, is presented in this paper. It has the components such as concepts, relations between concepts, and rules. The concepts in this model consist of attributes, facts and rules of itself. Each object in a concept has also equipped its behavior to solve problems on it. The methods for solving problems based on Rela-model are also studied. The general problems on this model are the following: Given some objects and facts on them, determine the closure of set of attributes and facts on the objects or determine an object or consider a relation between the objects. The algorithms to solve problems are designed and their properties, such as finiteness, effectiveness, have also been proved. Besides the solid mathematical foundation, Rela-model also has a simple specification language which can effectively represent the knowledge, thus it can be used in many real situations. Our approach is also applied to build two systems: the intelligent problem solver about solid geometry in high school mathematics, and the expert system to diagnose diseases in diabetic microvascular complication.
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Keser, Robert, Alberto Ceschin, Michele Battistoni, Hong G. Im und Hrvoje Jasak. „Development of a Eulerian Multi-Fluid Solver for Dense Spray Applications in OpenFOAM“. Energies 13, Nr. 18 (11.09.2020): 4740. http://dx.doi.org/10.3390/en13184740.
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The new generation of internal combustion engines is facing various research challenges which often include modern fuels and different operating modes. A robust modeling framework is essential for predicting the dynamic behavior of such complex phenomena. In this article, the implementation, verification, and validation of a Eulerian multi-fluid model for spray applications within the OpenFOAM toolbox are presented. Due to its open-source nature and broad-spectrum of available libraries and solvers, OpenFOAM is an ideal platform for academic research. The proposed work utilizes advanced interfacial momentum transfer models to capture the behavior of deforming droplets at a high phase fraction. Furthermore, the WAVE breakup model is employed for the transfer of mass from larger to smaller droplet classes. The work gives detailed instructions regarding the numerical implementation, with a dedicated section dealing with the implementation of the breakup model within the Eulerian multi-fluid formulation. During the verification analysis, the model proved to give stable and consistent results in terms of the selected number of droplet classes and the selected spatial and temporal resolution. In the validation section, the capability of the developed model to predict the dynamic behavior of non-evaporating sprays is presented. It was confirmed that the developed framework could be used as a stable foundation for future fuel spray modeling.
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Wang, Zhi, Qing Chen und Jia Chun Lin. „Finite Element Modality Analysis of Face Gear“. Applied Mechanics and Materials 278-280 (Januar 2013): 299–302. http://dx.doi.org/10.4028/www.scientific.net/amm.278-280.299.
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For improving the dynamic characteristics and reliability of the face gear, the finite element of the face gear was established with NX Advanced Simulation based on the theory of vibration mechanics and finite element method. the former 12 ranks of natural frequencies and shapes were calculated by using NX. Nastran solver, The results provided a direct theoretic basis for improving the design of the face gear. And it laid a foundation of dynamic response calculation of face gear at the same time.
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Tc, Widiastuti, und Yubali Ani, Ashiong Parhehean Munthe. „Pengembangan Diri Sebagai Fasilitator Belajar Pada Program Education Di Sentul Bogor“. Prosiding Konferensi Nasional Pengabdian Kepada Masyarakat dan Corporate Social Responsibility (PKM-CSR) 2 (14.12.2019): 782–90. http://dx.doi.org/10.37695/pkmcsr.v2i0.307.
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This activity is a continuation of the collaboration that began from the 2018-2019 term I academic year between the Pelita Harapan PGSD-FIP and the Emmanuel Foundation. Activities carried out include; this training is dedicated for learning facilitators to be able to teach creatively and practice their teaching skills at the location of their learning community. The objectives of the training activities are: 1) developing high school students themselves as learning facilitators; 2) lead learners who learn; 3) able to solve problems (problem solver), both for themselves and the environment; 4) being a creative learner; 5) excel in learning achievement; 6) direct practice in the learning community they lead. Implementation of activities in the form of training, including: 1) the provision of material; 2) question and answer session; 3) designing learning plans, making teaching aids, and compiling an assessment of the learning done; 4) games in groups with mentors; and 5) the practice of teaching directly individually in accordance with the plan for implementing the learning they have arranged. The activity takes place from July to December 2018, every Saturday 2 times a month. The training activities are provided help students have knowledge in the field of teaching, such as planning a lesson, making teaching aids, making simple judgments, and carrying out learning. Keywords: development, facilitator, problem solver, learning community
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Tandyo, Henry Novirga. „DESAIN SISTEM INFORMASI KEUANGAN PENDAPATAN UANG SEKOLAH PADA PERHIMPUNAN PENDIDIKAN (PERHIMPUNAN ABC)“. JURNAL AKUNTANSI UNIVERSITAS JEMBER 16, Nr. 1 (03.08.2018): 30. http://dx.doi.org/10.19184/jauj.v16i1.6893.
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Nonprofit organizations in the field of service generally focus on the services they provide. This resulted in a lack of attention to the company's internal controls, one of which is the financial field. This study aims to design standard operating procedures of school tuition income on educational foundations using the model of financial information systems. This research uses qualitative method with exploratory case study approach. In addition, researchers also participated directly in this research as a consultant. The results of this study indicate that workmanship in the field of finance has a problem related to the reliability of information displayed both in the form of financial statements and management reports. The absence of Standard Operating Procedure is a major cause of this problem. Standard Operating Procedures can be a problem solver in tracking any problems that result in the lack of financial reports and management reports on the Education Foundation.
Keywords: Financial Information System, Non-profit Organization, Revenue, Internal Control, Standard Operating Procedure.
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Strozzi, Antonio. „The Elastohydrodynamic Problem Expressed in Terms of Extended Variational Formulation“. Journal of Tribology 108, Nr. 4 (01.10.1986): 557–64. http://dx.doi.org/10.1115/1.3261263.
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The elastohydrodynamic problem is revisited in terms of an extended variational formulation, where the corresponding functional exhibits minimum properties in the solution neighborhood. Such features are exploited in the development of a relaxation-type solver. The numerical results indicate that the convergence rate of the proposed relaxation scheme becomes increasingly poor as the solution of the elastohydrodynamic problem is approached. A polyalgorithm based on a combination between relaxation-type and Newton-type schemes is proposed. The numerical experiments referred to various sealing profiles of increasing foundation compliance show that the proposed procedure is particularly advantageous in the case of soft lubricated contacts.
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Lee, Woo-Dong, Hyo-Jae Jo, Han-Sol Kim, Min-Jun Kang, Kwang-Hyo Jung und Dong-Soo Hur. „Experimental and Numerical Investigation of Self-Burial Mechanism of Pipeline with Spoiler under Steady Flow Conditions“. Journal of Marine Science and Engineering 7, Nr. 12 (12.12.2019): 456. http://dx.doi.org/10.3390/jmse7120456.
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Herein, hydraulic model experiments and numerical simulations were performed to understand the self-burial mechanism of subsea pipelines with spoilers under steady flow conditions. First, scour characteristics and self-burial functions according to the spoiler length-to-pipe diameter ratio (S/D) were investigated through hydraulic experiments. Further, the Navier–Stokes solver was verified. The experimental values of the velocity at the bottom of the pipeline with a spoiler and the pressure on the sand foundation where the pipeline rested were represented with the degree of conformity. Scour characteristics of a sand foundation were investigated from the numerical analysis results of the velocity and vorticity surrounding the pipelines with spoilers. The compilation of results from the hydraulic experiment and numerical analysis showed that the projected area increased when a spoiler was attached to the subsea pipes. This consequently increased the velocity of fluid leaving the top and bottom of the pipe, and high vorticity was formed within and above the sand foundation. This aggravated scouring at the pipe base and increased the top and bottom asymmetry of the dynamic pressure field, which developed a downward force on the pipeline. These two primary effects acting simultaneously under steady flow conditions explained the self-burial of pipelines with a spoiler attachment.
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Chang, J., D. Yu, W. Bao und L. Qu. „Dimensionless analysis of the unstart boundary for 2D mixed hypersonic inlets“. Aeronautical Journal 112, Nr. 1135 (September 2008): 547–55. http://dx.doi.org/10.1017/s0001924000002505.
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Abstract Inlet unstart boundary is one of the most important issues of the hypersonic inlet and is also the foundation of the protection control of a scramjet. To solve this problem, the 2D internal steady flow of a 2D mixed internal/external compression hypersonic inlet was numerically simulated at different freestream conditions and backpressures with a RANS (Reynolds-Averaged Navier-Stokes) solver using a RNG (Renormalisation Group) k-ε turbulence model, and two different inlet unstart phenomena were analysed. The dimensional analysis method was introduced to find the essence variables describing the inlet unstart boundary based on “numerical experimental” data in this paper. The dimensionless pressure ratios of the forebody and isolator were analysed respectively. The results show that the unstart boundary of the 2D mixed hypersonic inlet is determined by M0, α and Re0. Pressure ratio π increases with M0 increasing, and it increases firstly and decreases then with α increasing. Pressure ratio π increases with Re0 increasing. Re0 (Re0 < 2 × 107) has a major effect on π and Re0 (Re0 > 2×107) has little effect on π.
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Xu, Dianxiang, Ning Shen und Yunpeng Zhang. „Detecting Incorrect Uses of Combining Algorithms in XACML 3.0 Policies“. International Journal of Software Engineering and Knowledge Engineering 25, Nr. 09n10 (November 2015): 1551–71. http://dx.doi.org/10.1142/s021819401540032x.
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With the increasing complexity of software, new access control methods have emerged to deal with attribute-based authorization. As a standard language for specifying attribute-based access control policies, XACML offers a number of rule and policy combining algorithms to meet different needs of policy composition. Due to their variety and complexity, however, it is not uncommon to apply combining algorithms incorrectly, which can lead to unauthorized access or denial of service. To solve this problem, this paper presents a fault-based testing approach for revealing incorrect combining algorithms in XACML 3.0 policies. The theoretical foundation of this approach relies on the formalization of semantic differences between rule combining algorithms and between policy combining algorithms. It allows the use of a constraint solver for generating queries to which a given policy produces different responses than its combining algorithm-based mutants. Such queries can determine whether or not the given combining algorithm is used correctly. Our empirical studies using various XACML policies have demonstrated that our approach is effective.
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Xiao, Zhen Yan, Yun Gong und Yao Qing Gong. „Free Vibration Analysis for Step Tubular Structures of Tall Buildings Supported on Elastic Foundation Soil“. Applied Mechanics and Materials 166-169 (Mai 2012): 194–99. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.194.
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A method based on Ordinary Differential Equations (ODE) solver for free vibration analysis of tubular structures of tall buildings is developed, considering the deformation of the foundation soil as well as the interactions between the foundation and soil, by means of a three dimensional model with continuously distributed mass and stiffness. The nodal lines employed to discretize the computational model of the structures are one-variable functions defined on the nodal lines selected by the analyst to describe the dynamic behavior of the model. The unknown functions determined numerically herein are actual vibration modes that can be also recognized as the deformation functions of a set of conceptual structural components. By a Hamiltonian principle, the governing equations of the free vibration analysis can be obtained, which are a set of ordinary differential equations (ODE) of the vibration modes with their corresponding boundary conditions. The desired frequencies and corresponding vibration modes can be obtained by numerically solving the ODEs with boundary conditions. The method is applied to the tubular structures of tall buildings. The results from the illustration example show that the method is rational and powerful for the free vibration analysis of tall buildings.
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Bakhshandehrostami, Ali, Kai-Jia Han, Steven Parkinson, Laurens Alblas, William Collier und Flora C. W. Sun. „Verification of interface between an aeroelastic code and a time domain Rankine solver for completing structural analysis of floating wind turbine foundation design“. Journal of Physics: Conference Series 2018, Nr. 1 (01.09.2021): 012007. http://dx.doi.org/10.1088/1742-6596/2018/1/012007.
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Lin, Chuangxin, Vadim Monteiller, Kai Wang, Tianshi Liu, Ping Tong und Qinya Liu. „High-frequency seismic wave modelling of the deep Earth based on hybrid methods and spectral-element simulations: a conceptual study“. Geophysical Journal International 219, Nr. 3 (12.09.2019): 1948–69. http://dx.doi.org/10.1093/gji/ggz413.
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SUMMARY Over the past few decades, seismic studies have revealed complex structural anomalies in the Earth’s deep interior at various scales, such as large low-shear-velocity provinces (LLSVPs) and ultra-low velocity zones (ULVZs) in the lowermost mantle, and small-scale scatterers in the mid-mantle. These structures which are critical for better understanding of the geodynamics and evolution of the deep Earth, need to be further resolved by high-resolution imaging techniques. The spectral-element method (SEM) can be used to accurately simulate seismic wave propagation in heterogeneous Earth models, and its application in full-waveform inversion (FWI) provides a promising high-resolution and high-fidelity imaging technique. But it can be computationally prohibitive when used to model small scale structures in the deep Earth based upon high-frequency seismic waves. The heavy computational cost can be circumvented by using hybrid methods, which restrict the main computation by SEM solver to only a small target region (e.g. above the CMB) encompassing possible 2-D/3-D anomalies, and apply efficient analytical or numerical methods to calculate the wavefield for 1-D background models. These forward modelling tools based on hybrid methods can be then used in the so-called ‘box tomography’ approach to resolve fine-structures in the deep Earth. In this study, we outline the theory of a hybrid method used to model small scale structures in the deep Earth and present its implementation based on SEM solvers in a three-step workflow. First, the wavefield generated by the source is computed for the 1-D background model with traction and velocity saved for the virtual boundary of the target region, which are then used as boundary inputs to simulate the wavefield in the target region based on absorbing boundary condition in SEM. In the final step, the total wavefield at receivers is reconstructed based upon the total wavefield on the virtual boundary computed in the previous step. As a proof-of-concept study, we demonstrate the workflow of the hybrid method based on a 2-D SEM solver. Examples of the hybrid method applied to a coupled fluid–solid model show that our workflow can accurately recover the scattered waves back to the surface. Furthermore, we benchmark the hybrid method on a realistic heterogeneous Earth model built from AK135-F and show how teleseismic scattered waves can be used to model deep Earth structures. By documenting the theory and SEM implementation of the hybrid method, our study lays the foundation for future two-way coupling of 3-D SEM solver with other efficient analytic or numerical 1-D solvers.
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Benson, Rodney. „Can foundations solve the journalism crisis?“ Journalism 19, Nr. 8 (31.08.2017): 1059–77. http://dx.doi.org/10.1177/1464884917724612.
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In the context of the ongoing financial crisis in U.S. professional journalism, philanthropic foundation-supported nonprofits are increasingly proposed as a solution to the under-provision of civic-oriented news production. Drawing on an analysis of the social composition of boards of directors and interviews with foundation officials and nonprofit journalists, this article examines both the civic contributions and limitations of foundation-supported nonprofit news organizations. Foundations are shown to place many nonprofits in a Catch-22 because of competing demands to achieve both economic “sustainability” and civic “impact,” ultimately creating pressures to reproduce dominant commercial media news practices or orient news primarily for small, elite audiences. Further, media organizations dependent on foundation project-based funding risk being captured by foundation agendas and thus less able to investigate the issues they deem most important. Reforms encouraging more long-term, no-strings-attached funding by foundations, along with development of small donor and public funding, could help nonprofits overcome their current limitations.
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Scanlan, Kirk M., Michael T. Hendry, C. Derek Martin und Douglas R. Schmitt. „Evaluating the sensitivity of low-frequency ground-penetrating radar attributes to estimate ballast fines in the presence of variable track foundations through simulation“. Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 232, Nr. 4 (24.05.2017): 1168–81. http://dx.doi.org/10.1177/0954409717710408.
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The sensitivity of three low-frequency (<1 GHz) ground-penetrating radar attributes commonly used to infer the amount of fines present within railway ballast was evaluated using synthetic datasets. Variations in ballast thickness, saturation, and subballast material type are not often considered during laboratory or small-scale (few kilometres of track) field studies. If ground-penetrating radar were to be applied as a ballast degradation detection tool on a subdivision (hundreds of kilometres) scale, it is critical to assess the impact variations these track foundation conditions will have on the inferred amount of fines present within the ballast. In this analysis, a two-layer (ballast and subballast) track foundation model was incorporated into a series of ground-penetrating radar simulations where the physical dimensions and electromagnetic properties of the model were systematically varied. It was through the electromagnetic properties that the volumetric amount of fines and moisture present within the ballast and the type of subballast material were altered. The ground-penetrating radar response of each model was simulated using a finite-difference time-domain solver for Maxwell’s equations (gprMax). The amount of fines present in the ballast was then inferred through attributes calculated from the synthetic ground-penetrating radar measurements and related to the known model input. This comparison revealed that ambiguities in the ground-penetrating radar attribute amplitudes were common. Specific ground-penetrating radar attribute amplitudes could not be uniquely associated with the known amounts of fines present within the ballast as the other conditions in the track foundation (ballast saturation, ballast thickness, and subballast material) were varied. As such, a quantitative and reliable estimation for the amount of fines present within ballast using ground-penetrating radar measurements over large scales would be difficult without first constraining the variability in the track foundation.
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Fan, Jing Ming, Chang Ming Fan und Jun Wang. „Flow Dynamic Simulation of Micro Abrasive Water Jet“. Solid State Phenomena 175 (Juni 2011): 171–76. http://dx.doi.org/10.4028/www.scientific.net/ssp.175.171.
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Simulation of the dynamic characteristics of micro abrasive water jet (MAWJ) is conducted using computation fluid dynamics (CFD) software Fluent 6.3 flow solver. The velocity distributions and particle behaviors of the free jet and impinging jet in and out of the nozzle are investigated under different input and boundary conditions. In the free jet simulation, a reduction in water pressure corresponds to more rapid decay of the jet velocity along the jet axis, whereas particle mass concentration has no influence on the jet velocity. In the impinging jet simulation, the effect of the impingement surface on the flow field increases with a decrease of the stand-off distance. The simulation results in this study provide the foundation for optimizing the nozzle structure and improving cutting efficiency and cutting performance of MAWJ.
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Monteiro, Nuno P., und Keven G. Ruby. „IR and the false promise of philosophical foundations“. International Theory 1, Nr. 1 (März 2009): 15–48. http://dx.doi.org/10.1017/s1752971909000050.
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International Relations (IR) is uneasy about its status as a ‘science’. Throughout a long history of attempts to legitimate the field as ‘scientific’, IR scholars have imported multifarious positions from the Philosophy of Science (PoS) in order to ground IR on an unshakable foundation. Alas, no such unshakable foundation exists. The PoS is itself a contested field of study, in which no consensus exists on the proper foundation for science. By importing foundational divisions into IR, the ‘science’ debate splits the discipline into contending factions and justifies the absence of dialogue between them. As all foundations require a leap of faith, imperial foundational projects are always vulnerable to challenge and therefore unable to resolve the science question in IR. In this article, we seek to dissolve rather than solve the ‘science’ debate in IR and the quest for philosophical foundations. We argue that IR scholars should adopt an ‘attitude towards’ rather than a ‘position in’ the irresolvable foundational debate. Specifically, we advocate an attitude of ‘foundational prudence’ that is open-minded about what the PoS can offer IR, while precluding imperial foundational projects, which attempt to impose a single meta-theoretical framework on the discipline. This requires knowing what PoS arguments can and cannot do. As such, foundational prudence is post-foundational rather than anti-foundational. A prudent attitude towards philosophical foundations encourages theoretical and methodological pluralism, making room for a question-driven IR while de-escalating intra-disciplinary politics.
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Jia, Lan, Lan Zhu Cao und Zi Ling Song. „Based on Three-Dimensional Limit Equilibrium Slope Stability Analysis of Open Pit“. Advanced Materials Research 261-263 (Mai 2011): 1465–69. http://dx.doi.org/10.4028/www.scientific.net/amr.261-263.1465.
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As the complexity and the tall of open pit slope, two-dimensional slope stability analysis methods have been unable to meet the needs of the accuracy of stability analysis. Therefore, for the complex situation of Pingzhuang open pit slope, use with three-dimensional rigid body limit equilibrium method to analysisstability of slope.slope3D system, which consists of pre-treatment, limit equilibrium analysis solver and post-processing, the first processing core is to construct three-dimensional geological model of the slope, post-processing mainly results analysis and visualization graphics. The system combined organically the slope engineering geological information three-dimensional visualization and the analysis of stability, which make us to determine the landslide model, reveal the mechanism of landslide more accurately. Make an important contribution for ensuring safety in open pit production, a good foundation for slope stability analysis of other open pit.
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Hastings, Stuart. „John Bryce McLeod. 23 December 1929 — 20 August 2014“. Biographical Memoirs of Fellows of the Royal Society 62 (Januar 2016): 381–407. http://dx.doi.org/10.1098/rsbm.2015.0031.
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J. B. McLeod was a brilliant solver of problems in mathematical analysis, primarily differential equations. He received his FRS in 1992, and the citation reads in part: ‘Distinguished for many significant contributions to applied analysis, particularly to the theory of partial differential equations with applications to practical problems. … By the exemplary precision and power of his publications and his lectures, he has become internationally recognized as the leading British authority on the useful applications of functional analysis.‘ In addition, in 2011 McLeod was awarded the Naylor Prize and Lectureship of the London Mathematical Society ‘in recognition of his important and versatile achievements in the analysis of nonlinear equations arising in applications to mechanics, physics, and biology.’ He collaborated widely, and was a resource for many applied mathematicians who wanted to have a more rigorous foundation for their work. He leaves a hole that will be hard to fill.
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Yu, Ziying, Zhenhong Hu, Xing Zheng, Qingwei Ma und Hongbin Hao. „Aeroelastic Performance Analysis of Wind Turbine in the Wake with a New Elastic Actuator Line Model“. Water 12, Nr. 5 (26.04.2020): 1233. http://dx.doi.org/10.3390/w12051233.
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The scale of a wind turbine is getting larger with the development of wind energy recently. Therefore, the effect of the wind turbine blades deformation on its performances and lifespan has become obvious. In order to solve this research rapidly, a new elastic actuator line model (EALM) is proposed in this study, which is based on turbinesFoam in OpenFOAM (Open Source Field Operation and Manipulation, a free, open source computational fluid dynamics (CFD) software package released by the OpenFOAM Foundation, which was incorporated as a company limited by guarantee in England and Wales). The model combines the actuator line model (ALM) and a beam solver, which is used in the wind turbine blade design. The aeroelastic performances of the NREL (National Renewable Energy Laboratory) 5 MW wind turbine like power, thrust, and blade tip displacement are investigated. These results are compared with some research to prove the new model. Additionally, the influence caused by blade deflections on the aerodynamic performance is discussed. It is demonstrated that the tower shadow effect becomes more obvious and causes the power and thrust to get a bit lower and unsteady. Finally, this variety is analyzed in the wake of upstream wind turbine and it is found that the influence on the performance and wake flow field of downstream wind turbine becomes more serious.
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Dai, Jian, Kok Keng Ang, Van Hai Luong, Minh Thi Tran und Dongqi Jiang. „Out-of-Plane Responses of Overspeeding High-Speed Train on Curved Track“. International Journal of Structural Stability and Dynamics 18, Nr. 11 (22.10.2018): 1850132. http://dx.doi.org/10.1142/s0219455418501328.
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This paper presents a numerical study on the out-of-plane responses of a high-speed train running on a curved railway track segment using the moving element method. The accuracy and efficiency of the proposed computation model presented herein are compared with available analytical results from the literature and a finite element solver based on a simplified moving load model. Thereafter, a half-railcar moving sprung-mass model and a double-rail track-foundation model are presented to investigate the behavior of a high-speed train traversing a curved track, particularly when the train speed is greater than the design speed of the curved track segment. The results show that the train speed and severity of track irregularity significantly affect the contact forces on the rails. This paper also presents a case of a railcar overturning when the train speed is greater than 2.5 times the design speed of a curved track segment.
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Gore, Hunter, Luis Caldera, Xiao Shen und Firouzeh Sabri. „Computational Analysis of Structural Defects in Silica Aerogels“. MRS Advances 4, Nr. 46-47 (2019): 2479–88. http://dx.doi.org/10.1557/adv.2019.362.
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AbstractTechnological advances in synthesis and preparation of aerogels have resulted in formulations that have the mechanical integrity (while retaining flexibility) to be utilized in a broad range of applications and have overcome the initial brittleness that this class of materials was once known for. Both structural and functional aerogels show a drop in performance when subjected to certain cyclic thermal or impact loading due to the wear and formation of cracks, which reduces their lifespan. Here we present the proof-of-concept of a computational toolset that connects the change in thermal profile to structural failure and degradation. In combination with an appropriate finite element (FEM) solver, we have developed a genetic algorithm that can reconstruct the size and shape of the defective region in silica aerogels given the temperatures from a sensor grid. Results show that a heatmap can be used as the foundation for reconstructing faults and defects in thermally insulating materials. Furthermore, the model developed in this study can be expanded to accommodate other material types. Experimental setup can used to benchmark and refine the computational toolset.
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Fu, Guangming, Yudan Peng, Baojiang Sun, Chen An und Jian Su. „An exact GITT solution for static bending of clamped parallelogram plate resting on an elastic foundation“. Engineering Computations 36, Nr. 6 (08.07.2019): 2034–47. http://dx.doi.org/10.1108/ec-12-2018-0582.
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Purpose The purpose of this study is to propose generalised integral transform technique (GITT) to obtain the exact solutions for bending of clamped parallelogram plate resting on elastic foundation. Design/methodology/approach The GITT is used to solve the bending problem of the full clamped parallelogram plate under an elastic foundation. The auxiliary problem was developed and the corresponding eigenfunction and eigenvalue were calculated simultaneously. The original partial differential governed equation has been represented by the transformed ordinary differential equation system and solved by the subroutine DBVPFD from International Mathematics and Statistics Library. Findings The GITT has been proven to be an efficient approach to solve the bending problem of the plate with different loads, boundary conditions and elastic foundations. The parametric study indicates that the elastic foundation modulus has significant contribution in reducing the vertical deflections and moments for both rectangular and parallelogram plates. With the increasing of aspect ratio (a/b) and the elastic foundation modulus, the trends of the deflection and moment reduction decreased significantly. Originality/value The present hybrid analytical-numerical methodology was first used to solve the mechanics problem of the clamped parallelogram plate resting on elastic foundation. Excellent convergence and high accuracy was observed by comparing with the published results. It exhibits potential application to investigate the mechanics problem of the composite plate with different boundary conditions in the shipbuilding and civil engineering.
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Yue, Feng. „A Refined Model for Analysis of Beams on Two-Parameter Foundations by Iterative Method“. Mathematical Problems in Engineering 2021 (22.04.2021): 1–11. http://dx.doi.org/10.1155/2021/5562212.
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It is of great significance to study the interactions between structures and supporting soils for both structural engineering and geotechnical engineering. In this paper, based on the refined two-parameter elastic foundation model, the bending problem for a finite-length beam on Gibson elastic soil is solved. The effects of axial force and soil heterogeneity on the bending behaviours and stress states of beams on elastic foundations are discussed, and the parameters of the physical model are determined reasonably. The beam and elastic foundation are treated as a single system, and the complete potential energy is obtained. Based on the principle of minimum potential energy, the governing differential equations for the beam bearing axial force on the Gibson foundation are derived, and the equations for attenuation parameters are also defined. The problem of the unknown parameters in foundation models being difficult to determine is solved by an iterative method. The results demonstrate that this calculation method is feasible and accurate, and that the applied theory is universal for the analysis of interactions between beams and elastic foundations. Both axial force and soil heterogeneity have a certain effect on the deformation and internal force of beams on elastic foundations, and the vertical elastic coefficient of foundations is mainly determined by the stiffness of the surface soil. Additionally, attenuation parameters can be obtained relatively accurately by an iterative method, and then the vertical elastic coefficient and shear coefficient can be further obtained. This research lays a foundation for the popularisation and application of the two-parameter elastic foundation model.
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Shi, Xiao Min, Qiang Gao, Jian Jun Liu, Jian Guo Zhang, Da Bing Cheng und Nai Long Zhang. „Study on the Mechanism of Detecting Flaws in the Transmission Tower Foundation by the Finite Element Method“. Applied Mechanics and Materials 596 (Juli 2014): 12–16. http://dx.doi.org/10.4028/www.scientific.net/amm.596.12.
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Power transmission towers are major equipment of State Grid,the safety of the tower foundation is very important to the power system,nondestructive testing to foundations is necessary when excavation is impossible.In this paper, the dynamic response analysis of the impact-echo method for power transmission tower foundation with flaws is solved based on finite element method; the result of numerical analysis is consistent with the depth of the setting flaw, which shows the feasibility of detecting flaws in transmission tower foundations with the impact-echo method.
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Zhong, Huiying, Weidong Zhang, Hongjun Yin und Haoyang Liu. „Study on Mechanism of Viscoelastic Polymer Transient Flow in Porous Media“. Geofluids 2017 (2017): 1–8. http://dx.doi.org/10.1155/2017/8763951.
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Oil recovery, including conventional and viscous oil, can be improved significantly by flooding with polymer solutions. This chemical flooding method can increase oil production, and it can improve the macrodisplacement efficiency and microsweep efficiencies. In this study, we establish physical models that include the dead-end and complex models based on the pore-network pattern etched into glass, using the snappyHexMesh solver in OpenFOAM. These models capture the complexity and topology of porous media geometry. We establish a mathematical model for transient flows of viscoelastic polymers using computational fluid dynamics simulations, and we study the distributions of pressure and velocity for different elasticity scenarios and different flooding process. The results demonstrate that the pressure difference increases as the relaxation time decreases, before the flow reaches its steady state. For a steady flow, elasticity can give rise to an additional pressure difference, which increases with increasing elasticity. Thus, the characteristics of pressure difference vary before and after the flow becomes steady; this phenomenon is very important. Velocity contours become more widely spaced with elasticity increase. This suggests that elasticity of the polymer solutions contributes to the microsweep efficiency. The results of the study provide the necessary theoretical foundation for laboratory experiments and development of methods for polymer flooding and can be helpful for the design and selection of polymers for polymer flooding.
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Chen, Yang, Wen Zhao, Pengjiao Jia, Jianyong Han und Yongping Guan. „Dynamic Behavior of an Embedded Foundation under Horizontal Vibration in a Poroelastic Half-Space“. Applied Sciences 9, Nr. 4 (20.02.2019): 740. http://dx.doi.org/10.3390/app9040740.
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More and more huge embedded foundations are used in large-span bridges, such as caisson foundations and anchorage open caisson foundations. Most of the embedded foundations are undergoing horizontal vibration forces, that is, wind and wave forces or other types of dynamic forces. The embedded foundations are regarded as rigid due to its high stiffness and small deformation during the forcing process. The performance of a rigid, massive, cylindrical foundation embedded in a poroelastic half-space is investigated by an analytical method developed in this paper. The mixed boundary problem is solved by reducing the dual integral equations to a pair of Fredholm integral equations of the second kind. The numerical results are compared with existing solutions in order to assess the accuracy of the presented method. To further demonstrate the applicability of this method, parametric studies are performed to evaluate the dynamic response of the embedded foundation under horizontal vibration. The horizontal dynamic impedance and response factor of the embedded foundation are examined based on different embedment ratio, foundation mass ratio, relative stiffness, and poroelastic material properties versus nondimensional frequency. The results of this study can be adapted to investigate the horizontal vibration responses of a foundation embedded in poroelastic half-space.
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Song, Ji Qiang. „Pile Foundation Antifreezing Measures Research in Seasonal Frozen Soil Region“. Applied Mechanics and Materials 578-579 (Juli 2014): 767–71. http://dx.doi.org/10.4028/www.scientific.net/amm.578-579.767.
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Canal bridge and aqueduct main foundation types include well column, pier, bored piles, bent pile etc. Most of these foundations are in low-lying conduit. The water content of foundation soil is very rich. Especially pile foundation in the drain, due to the high underground water level, pile foundation around soil is in a state full of water. So such type of foundation freeze injury phenomenons are very serious. In order to solve such freeze injury problems, some antifreezing measures are adopted.
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Niedermayer, Uwe, A. Adelmann, S. Bettoni, M. Calvi, M. Dehler, E. Ferrari, F. Frei et al. „Challenges in simulating beam dynamics of dielectric laser acceleration“. International Journal of Modern Physics A 34, Nr. 36 (26.11.2019): 1942031. http://dx.doi.org/10.1142/s0217751x19420314.
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Dielectric Laser Acceleration (DLA) achieves the highest gradients among structure-based electron accelerators. The use of dielectrics increases the breakdown field limit, and thus the achievable gradient, by a factor of at least 10 in comparison to metals. Experimental demonstrations of DLA in 2013 led to the Accelerator on a Chip International Program (ACHIP), funded by the Gordon and Betty Moore Foundation. In ACHIP, our main goal is to build an accelerator on a silicon chip, which can accelerate electrons from below 100 keV to above 1 MeV with a gradient of at least 100 MeV/m. For stable acceleration on the chip, magnet-only focusing techniques are insufficient to compensate the strong acceleration defocusing. Thus, spatial harmonic and Alternating Phase Focusing (APF) laser-based focusing techniques have been developed. We have also developed the simplified symplectic tracking code DLAtrack6D, which makes use of the periodicity and applies only one kick per DLA cell, which is calculated by the Fourier coefficient of the synchronous spatial harmonic. Due to coupling, the Fourier coefficients of neighboring cells are not entirely independent and a field flatness optimization (similarly as in multi-cell cavities) needs to be performed. The simulation of the entire accelerator on a chip by a Particle In Cell (PIC) code is possible, but impractical for optimization purposes. Finally, we have also outlined the treatment of wake field effects in attosecond bunches in the grating within DLAtrack6D, where the wake function is computed by an external solver.
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Zhang, Heng, Chao Su, Jiawei Bai, Rongyao Yuan, Yujun Ma und Wenjun Wang. „The Rheological Analytical Solution and Parameter Inversion of Soft Soil Foundation“. Symmetry 13, Nr. 7 (08.07.2021): 1228. http://dx.doi.org/10.3390/sym13071228.
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In soft soil engineering projects, the building loads are always required to be symmetrically distributed on the surface of the foundation to prevent uneven settlement. Even if the buildings and soft clay are controlled by engineers, it can still lead to the rheology of the foundation. The analytical solution based on the Laplace integral transformation method has positive significance for providing a simple and highly efficient way to solve engineering problems, especially in the long-term uneven settlement deformation prediction of buildings on soft soil foundations. This paper proposes an analytical solution to analyze the deformation of soft soil foundations. The methodology is based on calculus theory, Laplace integral transformation, and viscoelastic theory. It combines an analytical solution with finite theory to solve the construction sequences and loading processes. In addition, an improved quantum genetic algorithm is put forward to inverse the parameters of soft soil foundations. The analytical solution based on Laplace integral transformation is validated through an engineering case. The results clearly illustrate the accuracy of the method.
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Huang, Tai Hua, Xian Yan Zhou und Ping Tan. „A Direct Solving Method for the Minimun Height of Rectangle Extended Foundation under Column that Meets the Punching Requirement“. Advanced Materials Research 639-640 (Januar 2013): 577–80. http://dx.doi.org/10.4028/www.scientific.net/amr.639-640.577.
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To meet the punching requirement of rectangle extended foundation under column, it is common practice to assume foundation’s height first, and then use the formula to check according to the current code. If the foundation’s height is not suitable, set it again to check until a suitable value. It is found that the minimum height of rectangle extended foundation under column can be solved directly, and all larger than the minimum height can meet the punching requirement through analysis program taking MATLAB as a platform for everyone to use.
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Asim Hamza, Ruba, und Amged Osman Abdelatif. „Foundations, Design, and Dynamic Performance of Wind Turbines: Overview and Challenges in Sudan“. FES Journal of Engineering Sciences 9, Nr. 1 (22.02.2021): 96–103. http://dx.doi.org/10.52981/fjes.v9i1.665.
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Sudan is one of the developing countries that suffers from a lack of electricity, where the national electrification rate is estimated at 38.5%. In order to solve this problem, it is possible to use renewable energy sources such as wind energy. Beside many aspects to be considered at the design of wind turbine foundations, more attention should be given to the geotechnical part. There are many types of foundations for wind turbines. The foundation must satisfy two design criteria: 1) It should be safe against bearing failure in soils under design loads and settlements during the life of the structure must not cause structural damage; 2) In addition to static loads, wind turbine foundations loads are extremely eccentrically and the loading is usually highly dynamic. Therefore, the selection of foundation type should consider these two criteria taking into account the nature and magnitude of these loads. This paper presents a review of different types of wind turbine foundations of focusing on on-shore wind turbine foundation types and the dynamic response of wind turbine. The paper also demonstrate experimentally the dynamic response of the wind turbines using wind tunnel facility test on a scaled model.
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Engel, Peter A., und Shou-Chien Chou. „Plastic Deformation of Solder Joints in Pin Grid Arrays Subjected to Thermal Stress“. Journal of Electronic Packaging 117, Nr. 2 (01.06.1995): 136–40. http://dx.doi.org/10.1115/1.2792080.
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In an earlier work [1], thermal stresses in soldered pins were calculated under the assumption of an elastically deforming solder barrel. In the present analysis, the nonlinear,temperature dependent stress-strain curve of solder, without creep, is taken into account, yielding an elasto-plastic foundation modulus function. For the thermal mismatch loading, the total temperature range ΔT (e.g., 0–100°C) is divided into a finite number n of temperature stages, and the final responses are superposed from the n contributions each of which done using an isothermal stress calculation. Three solders (Sn-Pb solders 63/37, 70/30, and 10/90), were investigated; the solder barrel thickness and mismatch temperature range were also variable parameters. Comparisons with elastic solder foundation calculation results show that thermal and inelastic solder stress/strain dependence should be included especially in the higher (over 75°C) temperature range.
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Zhang, Guang, Jun Rong Ma, Jing Xi Chen, Hua Lin Zhou und Dong Hua Wang. „Study on In Situ Shearing Strength Test for the Retaining Wall Bottom in a Bank Revetment Project“. Applied Mechanics and Materials 214 (November 2012): 333–37. http://dx.doi.org/10.4028/www.scientific.net/amm.214.333.
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To obtain the necessary shear strength parameters of the retaining wall bottom in a bank revetment project, in-situ shearing strength test must be conducted. There are 3 kinds of foundations. One is undisturbed soil foundation, and the other two are composite foundations. Due to the limited of the engineering conditions, each kind of foundation has prepared one specimen only. So the single shearing strength test can't separate cohesion c and friction angle φ. To solve this problem, a method which is a combination of shear strength test and sliding strength test is used. Sliding strength test is carried on specimens that have already failed after shearing strength test. This test is carried in wet conditions and cohesion values and friction angle values are obtained. In addition, the influence of the processing of composite foundation to equivalent friction coefficient is analyzed. Test result can be referenced by bank revetment projects which have similar geological conditions.
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Parsa Mahmoudi, Parisa, Hasan Mirzabozorg, Mehdi Varmazyari und Seyyed Meisam Aghajanzadeh. „Effect of Foundation Nonlinearity on Seismic Response of an Existing Arch Dam“. Civil Engineering Journal 2, Nr. 5 (30.05.2016): 197–207. http://dx.doi.org/10.28991/cej-2016-00000026.
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In the present paper, the effect of foundation nonlinearity on the seismic response of an existing arch dam is investigated. Luzzone arch dam in Switzerland is selected as a case study. The foundation nonlinearity is originated from opening/slipping of joints between a potential wedge at the left abutment and remaining foundation. Reservoir's water is assumed compressible and the coupled system is solved simultaneously. Also, the foundationis assumed massed medium via viscous boundary on the far-end truncated boundary. Two cases are considered in the analyses; the system applying reservoir pressure on the foundation; the system with no reservoir pressure applied on the foundation. The results reveal that the ignoringreservoir pressure on the foundation overestimates the response of the dam body. Finally, based on the conducted analyses, considering foundation nonlinearity has no significant effect on the results in the considered case due to special design of the body shape.
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Esteban, M., José-Santos López-Gutiérrez und Vicente Negro. „Gravity-Based Foundations in the Offshore Wind Sector“. Journal of Marine Science and Engineering 7, Nr. 3 (12.03.2019): 64. http://dx.doi.org/10.3390/jmse7030064.
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In recent years, the offshore wind industry has seen an important boost that is expected to continue in the coming years. In order for the offshore wind industry to achieve adequate development, it is essential to solve some existing uncertainties, some of which relate to foundations. These foundations are important for this type of project. As foundations represent approximately 35% of the total cost of an offshore wind project, it is essential that they receive special attention. There are different types of foundations that are used in the offshore wind industry. The most common types are steel monopiles, gravity-based structures (GBS), tripods, and jackets. However, there are some other types, such as suction caissons, tripiles, etc. For high water depths, the alternative to the previously mentioned foundations is the use of floating supports. Some offshore wind installations currently in operation have GBS-type foundations (also known as GBF: Gravity-based foundation). Although this typology has not been widely used until now, there is research that has highlighted its advantages over other types of foundation for both small and large water depth sites. There are no doubts over the importance of GBS. In fact, the offshore wind industry is trying to introduce improvements so as to turn GBF into a competitive foundation alternative, suitable for the widest ranges of water depth. The present article deals with GBS foundations. The article begins with the current state of the field, including not only the concepts of GBS constructed so far, but also other concepts that are in a less mature state of development. Furthermore, we also present a classification of this type of structure based on the GBS of offshore wind facilities that are currently in operation, as well as some reflections on future GBS alternatives.
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Zhou, Qiang, und Tong Wang. „Free Vibrations of an Elastically Restrained Euler Beam Resting on a Movable Winkler Foundation“. Shock and Vibration 2019 (13.06.2019): 1–15. http://dx.doi.org/10.1155/2019/2724768.
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The traditional theory of beam on elastic foundation implies a hypothesis that the elastic foundation is static with respect to the inertia reference frame, so it may not be applicable when the foundation is movable. A general model is presented for the free vibration of a Euler beam supported on a movable Winkler foundation and with ends elastically restrained by two vertical and two rotational springs. Frequency equations and corresponding mode shapes are analytically derived and numerically solved to study the effects of the movable Winkler foundation as well as elastic restraints on beam’s natural characteristics. Results indicate that if one of the beam ends is not vertically fixed, the effect of the foundation’s movability cannot be neglected and is mainly on the first two modes. As the foundation stiffness increases, the first wave number, sometimes together with the second one, firstly decreases to zero at the critical foundation stiffness and then increases after this point.
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Sulardi, Sulardi, Pria Agung Widodo, Abdi Suprayitno, Hamriani Ryka, Rohima Sera Afifah und Kukuh Jalu Waskita. „PONDASI BALIK KOTAK DITANAH LUNAK“. INFO-TEKNIK 21, Nr. 2 (25.01.2021): 163. http://dx.doi.org/10.20527/infotek.v21i2.10051.
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The problem is the difficulty in determining the type and method of manufacture and installation of foundation on soft soils. The research objective is to provide an overview of the type of foundation, the method of manufacture and the method of installation of the foundation which is suitable and suitable in the soft soil environment. This research method uses used research methods with trial and error, and with a case study approach method, namely the case of difficulties in overcoming the problem of the availability of permanent structural support foundations and refinery operation equipment on soft soil. The results showed that the type and shape of the foundation that is suitable and to solve the problem is the foundation behind the box. This foundation specification is an inverted box with reinforced concrete material and certain dimensions with cover plates. The results of this used research also show that the inverted box type of foundation is suitable for supporting equipment supporting refinery operations such as pipe supports and other refinery operation equipment.