Abstract

At present, the researches on the mechanical properties of sand aggregate mainly focus on the shaping process of particles, and lack the researches on the crushing mechanism. This paper first defines the shaping process of stone powder wall, and explores the crushing mechanism of sand aggregate by adopting multiple times of small energy crushing. The effect of energy is investigated by simulation and experiment. The machine-made sand crushing mechanism is analyzed by establishing corresponding contact mathematical models. The result shows that the stone powder wall involves two mathematical models under impact: the elastic-plastic model at low impact velocity and the elastic-brittle model at high impact velocity. '''Key words:''' machine-made sand; stone powder wall; crushing mechanism; mechanical contact model

Abstract

A design and load analysis of interleaved flyback converter with H6 inverter topology is proposed. Flyback converter is one among the DC-DC converter with high frequency which is used or low power applications. Because of high frequency operation switching losses and stresses are more. To reduce stresses and losses across the switch of interleaved flyback converter is proposed. In the grid tied inverter system leakage current is one of the disadvantages and to avoid this H6 type inverter is used. With this advantage of H6 inverter and flyback converter this paper is mainly focused on stresses across switches and eliminating leakage current, harmonic reduction. Further the fast switching is proposed within converter in order to deliver maximum power transfer delivered to load through grid. To validate the overall performance the proposed converter modeled in MATLAB-SIMULINK and prototype developed using DSP DSP TMS320F28377S and connected to grid connected load.

Abstract

This paper deals with mathematical modeling of Permanent magnet brushless DC (BLDC) motor in MATLAB-SIMULINK environment. Modeling of BLDC motor carried in transfer function, transfer equations and state space model to verify the performance as actuators. Mathematical switches to control electronic commutation of BLDC motor based on signals of Hall Effect position sensor using threephase inverter drive. Performance of the simplified mathematical inverter fed BLDC motor under steady state and dynamic conditions analyzed. Due to the switching losses during PWM generation generates low ripple content in torque of BLDC motor which described and eliminated through state space model. Comparison made of proposed modeling of BLDC motor with motor parameters like back-EMF, stator current and speed of BLDC motor, proposed work suggests the state space modeling holds a superior method for design of BLDC motor during high dynamic load performance and operating ranges

Abstract

The complexity of the dynamic response of offshore marine structures requires advanced simulations tools for the accurate assessment of the seakeeping behaviour of these devices. This presentation introduces a new time-domain model for solving the dynamics of moored floating marine devices, specifically offshore wind turbines, subjected to non-linear environmental loads. Different application examples are presented,including a GVA, and the OC3 and OC4 platforms. 

Abstract

This presentation shows the recent work of the CIMNE in the maritime transport field. It was given at the Conference on Computation and Big Data in Transport (CM3-2017) held in November 22 – 23, 2017.

Abstract

A Wave Adaptive Modular Vessel (WAM-V®) is a new class of ship that uses inflatable flexible hulls to conform to the surface of the water. It is similar in design to a catamaran, in that it has a twin hull design and no keel. However, the superstructure is not rigidly attached to the hulls; it uses shock absorbers and ball joints to articulate the vessel, which allows WAM-V to conform to the surface of the water while mitigating the stresses transmitted to the structure. Moreover, the inflatable hulls help to absorb the high frequency wave-loads. These features allow WAM-V to travel efficiently with low wave resistance in rough seas, by surfing on top of the waves rather than cut through them. The objective of the WAM-V is to be a lightweight watercraft capable of moving fast and efficiently on the surface of the sea. WAM-Vs are designed to allow for a variety of applications for either manned or unmanned operations and can be built in different lengths to match specific services. This presentation shows part of the work done in the project ‘Advanced Numerical Simulation and Performance Evaluation of WAM-V ® in Spray Generating Conditions’ developed by the International Center for Numerical Methods in Engineering (CIMNE) under Navy Grant N62909-12-1-7101 issued by the Office of Naval Research Global. The scope of that project included the performance analysis of the WAM-V in waves, taking into account the flexibility of the ship hulls, using fluid-structure interaction computational models. However, the focus of this paper is one of the primary concerns of that project; the development of a computational model for simulation of the WAM-V under spray generating conditions. In this regards, the final goal was to develop and demonstrate a computational engineering solver that could be used to design strategies to reduce the spray generation of the vessel.

Abstract

This presentation shows the recent work of the authors in the development of a time-domain FEM model for evaluation of the seal dynamics of a surface effect ship. The fluid solver developed for this purpose, uses a potential flow approach along with a stream-line integration of the free surface. The presentation focuses on the free surface-structure algorithm that has been developed to allow the simulation of the complex and highly dynamic behavior of the seals in the interface between the air cushion, and the water. The developed fluid-structure interaction solver is based, on one side, on an implicit iteration algorithm, communicating pressure forces and displacements of the seals at memory level and, on the other side, on an innovative wetting and drying scheme able to predict the water action on the seals. The stability of the iterative scheme is improved by means of relaxation, and the convergence is accelerated using Aitken’s method. Several validations against experimental results have been carried out to demonstrate the developed algorithm.

Abstract

Wave-structure interaction is a topic of great interest in naval and offshore engineering. This interest is growing in the last years due to the boost given by the development of the marine renewable energy field. In this context the development of an efficient time-domain coupled waves-structure solver is a main request from the industry. Up to date the numerical seakeeping simulation has been mostly carried out using the frequency domain. The reason might be that the computational cost of time domain simulations were too high and computational time was too large. Moreover assumptions like linear waves and the harmonic nature of water waves made the frequency domain to be the right choice. However nowadays computing capabilities make possible to carry out numerical simulations in the time domain in a reasonable time, with the advantage of making easier the introduction of non-linearities into the algorithm and therefore coupling with other phenomena. This presentation shows the work of the authors in developing a time-domain unstructured Finite Element Method (FEM) algorithm for analysis of coupled wave-structure interaction. For this purpose, a new diffraction-radiation solver using the FEM was developed. The solver has been implemented in GPU, using CUDA architecture. The speed-up obtained ranges from 5 to 10 times compare to the implementation in a standard CPU with a conjugate gradient and ILU preconditioner. The seakeeping analysis tool has been integrated within a coupled waves-structure analysis tool. The coupling algorithm is based on a partitioned iterative algorithm, using an interpolation library able to communicate pressure forces and displacements of the structure at memory level. Furthermore, an innovative wetting and drying scheme able to improve the evaluation of the water action on the structure. The accuracy of the new seakeeping formulation for analysis of waves and floating structures interaction has been verified in different validation cases and practical applications. 

Abstract

The digitization process applied to the construction sector seems to be articulated through the "Building Information Modeling" (BIM), which, as is well known, includes not only the three-dimensional (3D) representation of the works, but its many other dimensions, such as temporal information, budget, sustainability, services, etc. The BIM, as a technology, process and ecosystem, is effectively offering solutions for the entire life cycle of a project, in its design, execution and operation phases, and for all the agents linked to it, that is, for all the professionals of the construction sector without exception. The BIMtable concept is born from considering that it is precisely the construction, the most complex environment - changing and severe - the most interesting scenario to incorporate the novelties offered by the BIM, as well as all the technologies that complement it, to achieve the digitalization of the construction in its broadest sense. It is at the work site where real-time monitoring of its progress can be made, using sensors, IoT, cameras or the information provided by the workers themselves. It is in the construction where the different professionals need to access the information of the project, as it has been developed and modeled, to follow and execute the instructions of the architect.