Study on the Effect of Heat-Input on the Thickness of the Heat-Affected Zone of the SUS316L Steel Welded Joint by Numerical Simulation

The thickness of the heat-affected zone (HAZ) has a great influence on the strength of the welded joint, so one of the important tasks is to control the HAZ to a small enough level, through using the suitable heat-input (qd). In this study, the authors use SYSWELD software to compute and build a relationship between the heat-input and the thickness of the heat-affected zone in the plate thickness direction to find the right heat-input for researched welding joint. The simulation results show that when welding the root pass with qd > 552 J/mm and the cap pass with 754 J/mm < qd < 1066 J/mm, the thickness of HAZ were increased with a function almost linearly.

Solutions of Navier-Stokes Equations with Coriolis Force in the Rotational Framework

In this article, for 0 ≤m<∞ and the index vectors q=(q_1,q_2 ,q_3 ),r=(r_1,r_2,r_3) where 1≤q_i≤∞,1<r_i<∞ and 1≤i≤3, we study new results of Navier-Stokes equations with Coriolis force in the rotational framework in mixed-norm Sobolev-Lorentz spaces H ̇^(m,r,q) (R^3), which are more general than the classical Sobolev spaces. We prove the existence and uniqueness of solutions to the Navier-Stokes equations (NSE) under Coriolis force in the spaces L^∞([0, T]; H ̇^(m,r,q) ) by using topological arguments, the fixed point argument and interpolation inequalities. We have achieved new results compared to previous research in the Navier-Stokes problems.

Context-Based Movie Searching Using Semantic Web

When searching for a movie, users often remember only the incidents happened in the movie instead of the actors or directors of that movie. However, these searches are not supported in our current movie information systems as data query is usually based on keywords. This research proposes a solution to search and query movies based on the content of the movie or the incidents happened in the movie. In our research, we have analysed and designed some movie representation models suitable for context-based movie searching. We also propose a quadruple-based representation model to resolve the disadvantages in current semantic web’s triple-based model. Our system is capable of processing user requests precisely and has proven to have advantages over current movie information systems.

Research on the Fast and Accurate Estimation Method of Sag Voltage

Sag voltage affects the quality of the grid voltage and the working conditions of the electrical equipment. In order to prevent effectively this problem, the authors investigated the estimation method of fast and accurate voltage and phase angle in the presence of sag voltage. The method proposed Least Error Squares (LES) were constructed on the basis of the least squares algorithm and Taylor series expansion. Compared with conventional Clark and Park methods, the LES approach has the following major advantages: faster detection time, reduced deviation of estimated voltage values at the time of failure; faster detection time, reduced deviation of estimated voltage values at the time of failure; being not affected by other fundamental components 50Hz, the DC components in the grid. The effectiveness of the method is verified by simulation model of a distribution grid in Vinh Phuc province by Matlab / SIMULINK software.

Optimization of the Possibility of Dropping Materials on the Flip-over Bridge for Cassava Roots with Lifting Capacity of 60-80 tons

The paper presents the results of a survey on the ability to vent and dropping materials of the lift-over bridge for cassava roots with a lifting capacity of 60-80 tons based on the experimental planning model. The content of the survey on the influence of technological and technical parameters on the ability of venting/dropping materials on cassava trucks when the system of lifting-flip equipment uses transmission and hydraulic control. The research results build regression equations to show the influence relationship between the three basic structural parameters as lifting load, lift angle, distance A. Optimizing multi-objective function with Box Behnken algorithm model, the optimal conditions are as follows: A 5000 mm, lift angle 39.88 degree, lifting load 60.000 kg. Under these conditions, the highest guessing performance is 86,6%, then the objective function achieves the expected value of product clearance 99.9%, specific energy consumption 6.9 kW/h. There is no much difference in the results between the regression model and the experimental results which are similar almost similar.

Modeling and Calculating of Residual Stress and Strain of Butt Welded Joint

The non-uniform thermal expansion and contraction resulting from welding processes cause residual stresses and strains. Experimental studies on measuring welding residual stresses and strains of structure are costly and sometimes they are not possible. Previously, analytical methods with idealized models were developed to determine the welding residual stresses and strain. Recently, numerical methods are constructed to analyze the stresses and the strains in welded structures. This paper presents the calculation results of residual stress and welding strain in butt welded joint of S355J2G3 carbon steel of 5 mm thickness made by MAG welding process with a single pass. The calculation is performed by two methods: the imaginary force method and the finite element method. In the finite element method, the SYSWELD software is used to simulate and to determine residual stresses and strain of this welded joint. The results of finite element method are compared with those of imaginary force method to show the rationality and the advantages of finite element method. The study results have shown that in this welded joint, only the longitudinal and transverse stress components are important and the other stress components are negligible.

A Dynamical Study of a Rotor Supported by a Radial Journal Bearing Incorporating a Spherical Squeeze Film Damper

The reduction of noises, vibration, and mechanical waves transmitting through water from the shells of submarines is essential to their safe operation and travelling. Vibrations from the rotors of the engines are widely deemed as one of the main sources to which engineers have tried to attenuate with various designs. Squeeze-film dampers can be easily integrated into rotor-bearing structures in order to lower the level of vibrations caused by rotors out of balance. For this advantage, squeeze-film dampers are widely used in air-turbine engines. This paper presents preliminary results of a numerical simulation of a shaft running on a journal bearing integrated with a squeeze-film damper and evaluates the capacity in reducing vibrations concerning the stability of static equilibrium of the shaft journal center. The proposed damper is designed in spherical shape with self-aligning capacity. The results were obtained using finite difference method and numerical integration of the full nonlinear equations of motion.

Testing Oscillation and Optimization of the Motorcycle Frame Body Using Co-Simulation Method

The article is devoted to researching the durability of motorcycle frames with calculated loads in some cases of actual vehicle operation based on Vietnamese standards. The paper uses the multi-body system method to build a dynamic model suitable for the actual test problem according to the standard and optimize the mass of the motorcycle frame by the finite element analysis. The study includes an overview and analysis when choosing a motorcycle frame commonly used in Vietnam. A motorcycle frame of Wave brand is used to calculate and test the chassis durability with different parameters. Various internal loading modes are applied to the multi-body system model to help optimize the vehicle chassis mass by using specialized software. The authors calculated the load, built a durability model with static loads in practical working situations, built a multi-object system model to investigate the vehicle dynamics problem with the standards. This paper leads to the problem of optimizing the chassis thickness to reduce the weight of the chassis. Computers and optimization tools help engineers to save much time in the product design process. Investigating product optimization helps solve problems quickly, finding the best design, assisting engineers in developing the best strategies, and reducing time and costs during prototyping and testing.

A Simulation of Four Stroke Marine Diesel Engines to Predict Internal Cylinder Characteristics

This paper introduces a simulation of four-stroke marine diesel engines. The submodel of a particular cylinder was carried out, based on the first law of thermodynamics, programmed by Matlab/Simulink program, which describes the relations among internal characteristics, including cylinder performance parameters, heat release, heat loss, and pressure. The heat release is based on the Wiebe function and the heat loss is based on the Woschni function to build submodels. From the result of the model, the indicated pressure of a single cylinder was taken, the brake power of the engine could be estimated through this pressure. The object of the simulation is a new engine, hence the technical documents and test records provided by the manufacturer are sufficient. The model got the input parameters from this and the key outputs of the model (for example the brake power, peak combustion pressure, specific fuel consumption) were compared with the test records to adjust and make it more accurate. These gaps were not over 5%, therefore, this model can be used to predict key complicated internal cylinder characteristics, for example, the pressure, temperature, and thermal efficiency of engines.

Temperature Field in MIG Welding of Thin Plate of Stainless Steel

This paper studies the butt welded joint of SUS316L stainless steel. The butt joint is not beveled, has a gap and is welded in one pass by MIG welding process. First, the welding parameters of this weld are determined through calculation and test welding for the butt joint of two plates of 3 mm in thickness. Then these welding parameters are used as input data to calculate and determine the temperature field by two methods: the calculation method based on the theory of heat transfer process and the numerical simulation method of welding processes that relies on SYSWELD software on the basis of the finite element method. The calculation results of the two methods were compared with each other and tested by experiment to show the reliability of calculation and simulation results.