scholarly journals All-Weather Thermal Simulation Methods for Concrete Maglev Bridge Based on Structural and Meteorological Monitoring Data

Sensors ◽  
2021 ◽  
Vol 21 (17) ◽  
pp. 5789 ◽  
Author(s):  
Ao Wang ◽  
Zongkai Zhang ◽  
Xiaoming Lei ◽  
Ye Xia ◽  
Limin Sun
Keyword(s):  
Temperature Distribution ◽  
Solar Radiation ◽  
Real Time ◽  
Thermal Energy ◽  
Energy Exchange ◽  
Simulation Method ◽  
Thermal Simulation ◽  
Concrete Bridge ◽  
Structural Temperature ◽  
Bridge Structures

Thermal energy exchange induces non-uniform temperature distribution on the concrete bridge structures, leading to variation of static and dynamic properties of structural systems. The finite element method can facilitate thermal simulation and predict the structural temperature distribution based on heat flow theories. Previous studies mainly focused on the daytime with sunny weather, and the effects of solar shadow distribution were not fully considered or even ignored. In this paper, a systematic all-weather thermal simulation method was proposed to investigate the temperature distributions of concrete maglev bridges. The solar shadow distribution on the bridge surface could be accurately simulated to determine the solar radiation-imposed range. A meteorological station and some thermocouples were installed on a real concrete maglev bridge to obtain the real-time structural temperatures and environmental conditions. Its temperature distribution is also simulated using the proposed method within the 27 monitoring days in Summer. Results show that the simulated structural temperature matches well with the measured results under various weather conditions, except that of the east structural surface. Moreover, the simulation method acquired a higher accuracy under overcast or rainy weather due to weaker solar radiation effects. Both the numerical results and experimental records illustrated that direct solar radiation dominates the thermal energy exchange under sunny or cloudy conditions. The proposed methodology for temperature field simulation is oriented by all-weather prediction of structural temperature, which is reliable for concrete bridge structures with the help of accurate measurement of real-time solar radiation.

Assessment on the Thermal Stresses of Concrete Bridge Piers under Solar Radiation

2012 ◽  
Vol 204-208 ◽  
pp. 2045-2050 ◽  
Author(s):  
Pei Song Gong ◽  
Bo Chen ◽  
Chun Fang Song ◽  
Xiu Li Li
Keyword(s):  
Temperature Distribution ◽  
Boundary Conditions ◽  
Thermal Stresses ◽  
Numerical Models ◽  
Bridge Pier ◽  
Concrete Bridge ◽  
Time Varying ◽  
Thermal Boundary Conditions ◽  
Infrared Imager ◽  
Structural Temperature

The time-varying thermal stresses of a concrete pier are actively studied in this study with the aiding of the commercial package ANSYS. Thermal boundary conditions are utilized to obtain the temperature distribution of the concrete bridge pier. The surface temperature of the pier is measured by using a thermal infrared imager at different time instants. The different boundary conditions are applied to determine the structural temperature distribution and compute the thermal deformation. The made observations demonstrate that the horizontal deformation is much larger than that in vertical deformation due to the influence of the constraints on the top and bottom sides of the pier. The thermal stresses of the example bridge pier are not very large except for the local areas on top of the piers. It is seen that the numerical models can successfully predict the structural time-varying temperature effects

A real-time control method-based simulation for high-speed trains on large-scale rail network

2017 ◽  
Vol 28 (10) ◽  
pp. 1750126 ◽  
Author(s):  
Yutong Liu ◽  
Chengxuan Cao ◽  
Yaling Zhou ◽  
Ziyan Feng
Keyword(s):  
Real Time ◽  
Traffic Flow ◽  
High Speed ◽  
Large Scale ◽  
Simulation Method ◽  
Real Time Control ◽  
Rail Network ◽  
Time Control ◽  
High Speed Trains ◽  
Rail Traffic

In this paper, an improved real-time control model based on the discrete-time method is constructed to control and simulate the movement of high-speed trains on large-scale rail network. The constraints of acceleration and deceleration are introduced in this model, and a more reasonable definition of the minimal headway is also presented. Considering the complicated rail traffic environment in practice, we propose a set of sound operational strategies to excellently control traffic flow on rail network under various conditions. Several simulation experiments with different parameter combinations are conducted to verify the effectiveness of the control simulation method. The experimental results are similar to realistic environment and some characteristics of rail traffic flow are also investigated, especially the impact of stochastic disturbances and the minimal headway on the rail traffic flow on large-scale rail network, which can better assist dispatchers in analysis and decision-making. Meanwhile, experimental results also demonstrate that the proposed control simulation method can be in real-time control of traffic flow for high-speed trains not only on the simple rail line, but also on the complicated large-scale network such as China’s high-speed rail network and serve as a tool of simulating the traffic flow on large-scale rail network to study the characteristics of rail traffic flow.

Shear Assessment of Concrete Bridge Deck Slabs

2017 ◽  
Vol 738 ◽  
pp. 110-119 ◽  
Author(s):  
Radoslav Vida ◽  
Jaroslav Halvonik
Keyword(s):  
Current Model ◽  
Shear Capacity ◽  
Concrete Bridge ◽  
Current Standard ◽  
Concrete Members ◽  
Deck Slabs ◽  
Bridge Structures ◽  
Bridge Deck Slabs ◽  
Concrete Bridge Deck ◽  
New Generation

The transitions from old STN standards to Eurocode standards brought several problems into bridge design and assessment. Shear reinforcement is now often required even in concrete members, which were previously allowed to be built without it. Moreover, assessment of existing reinforced concrete bridge structures often shows their insufficiency in shear capacity, which means that they should be strengthened or replaced. Work on new generation of Eurocodes is currently in progress and current model for shear assessment should be replaced by a new (and more precise) one. This paper deals with the problem of shear assessment of concrete bridge according to current standard and also according to the new shear models that are under consideration.

Non-uniform temperature distribution of the main reflector of a large radio telescope under solar radiation

2021 ◽  
Vol 21 (11) ◽  
pp. 293
Author(s):  
Shan-Xiang Wei ◽  
De-Qing Kong ◽  
Qi-Ming Wang
Keyword(s):  
Temperature Field ◽  
Temperature Distribution ◽  
Solar Radiation ◽  
Radio Telescope ◽  
Thermal Imaging ◽  
Uniform Temperature ◽  
Large Radio Telescope ◽  
Uniform Temperature Distribution ◽  
Uniform Temperature Field ◽  
Main Reflector

Abstract The non-uniform temperature distribution of the main reflector of a large radio telescope may cause serious deformation of the main reflector, which will dramatically reduce the aperture efficiency of a radio telescope. To study the non-uniform temperature field of the main reflector of a large radio telescope, numerical calculations including thermal environment factors, the coefficients on convection and radiation, and the shadow boundary of the main reflector are first discussed. In addition, the shadow coverage and the non-uniform temperature field of the main reflector of a 70-m radio telescope under solar radiation are simulated by finite element analysis. The simulation results show that the temperature distribution of the main reflector under solar radiation is very uneven, and the maximum of the root mean square temperature is 12.3°C. To verify the simulation results, an optical camera and a thermal imaging camera are used to measure the shadow coverage and the non-uniform temperature distribution of the main reflector on a clear day. At the same time, some temperature sensors are used to measure the temperature at some points close to the main reflector on the backup structure. It has been verified that the simulation and measurement results of the shadow coverage on the main reflector are in good agreement, and the cosine similarity between the simulation and the measurement is above 90%. Despite the inevitable thermal imaging errors caused by large viewing angles, the simulated temperature field is similar to the measured temperature distribution of the main reflector to a large extent. The temperature trend measured at the test points on the backup structure close to the main reflector without direct solar radiation is consistent with the simulated temperature trend of the corresponding points on the main reflector with the solar radiation. It is credible to calculate the temperature field of the main reflector through the finite element method. This work can provide valuable references for studying the thermal deformation and the surface accuracy of the main reflector of a large radio telescope.

scholarly journals SHIL and DHIL Simulations of Nonlinear Control Methods Applied for Power Converters Using Embedded Systems

Electronics ◽  
2018 ◽  
Vol 7 (10) ◽  
pp. 241 ◽  
Author(s):  
Arthur Rosa ◽  
Matheus Silva ◽  
Marcos Campos ◽  
Renato Santana ◽  
Welbert Rodrigues ◽  
...  
Keyword(s):  
Embedded Systems ◽  
Nonlinear Control ◽  
Real Time ◽  
Digital Signal Processor ◽  
High Performance ◽  
Power Converters ◽  
Digital Signal ◽  
Simulation Method ◽  
Hardware In The Loop ◽  
Control Techniques

In this work, a new real-time Simulation method is designed for nonlinear control techniques applied to power converters. We propose two different implementations: in the first one (Single Hardware in The Loop: SHIL), both model and control laws are inserted in the same Digital Signal Processor (DSP), and in the second approach (Double Hardware in The Loop: DHIL), the equations are loaded in different embedded systems. With this methodology, linear and nonlinear control techniques can be designed and compared in a quick and cheap real-time realization of the proposed systems, ideal for both students and engineers who are interested in learning and validating converters performance. The methodology can be applied to buck, boost, buck-boost, flyback, SEPIC and 3-phase AC-DC boost converters showing that the new and high performance embedded systems can evaluate distinct nonlinear controllers. The approach is done using matlab-simulink over commodity Texas Instruments Digital Signal Processors (TI-DSPs). The main purpose is to demonstrate the feasibility of proposed real-time implementations without using expensive HIL systems such as Opal-RT and Typhoon-HL.

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