31 Full-scale forced vibration studies and mathematical model formulation of arch concrete dams

1981 ◽  
pp. 275-285 ◽  
Author(s):  
T. A. Paskalov ◽  
J. T. Petrovski ◽  
D. V. Jurukovski
Keyword(s):  
Mathematical Model ◽  
Forced Vibration ◽  
Full Scale ◽  
Concrete Dams ◽  
Model Formulation

Infeasibility and Non-Optimality Tests for Solution Space Reduction in Discrete Optimal Design

1992 ◽  
Author(s):  
Leonard P. Pomrehn ◽  
Panos Y. Papalambros
Keyword(s):  
Mathematical Model ◽  
Solution Space ◽  
Global Optimum ◽  
Gear Train ◽  
Discrete Variables ◽  
Multistage Process ◽  
Model Formulation ◽  
Space Reduction ◽  
Nonlinear Design ◽  
The Mathematical Model

Abstract Techniques to be employed for nonlinear design optimization with discrete variables are studied in the context of a particular problem arising from the design of a gear train. The mathematical model formulation was presented in an earlier article. In this sequel, a solution derivation is described, patterned as a multistage process. After certain reformulation and relaxation, a variety of infeasibility and non-optimality tests are performed, greatly reducing the size of the space containing the global optimum. Methods used to investigate the remaining space do not guarantee a global optimum, but could be replaced by more costly methods that do provide such guarantees. A global infimum is generated, bounding any improvements on the best known solution.

scholarly journals Model of the dynamics of a wheeled vehicle for a complex of full-scale-mathematical modeling

2020 ◽  
Vol 1 (4) ◽  
pp. 46-60
Author(s):  
B.B. Kositsyn ◽  
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Real Time ◽  
Block Diagram ◽  
Plane Motion ◽  
Full Scale ◽  
Practical Significance ◽  
Modes Of Operation ◽  
Wheeled Vehicle ◽  
Full Scale Tests

Introduction. The use of the method of full-scale-mathematical modeling in “real time” opens up wide opportunities associated with the analysis of the modes of operation of the “man – vehicle – environment” system, as well as the study of the loading of units and assemblies of vehicles. The existing research complexes of full-scale mathematical modeling are suitable for obtaining most of the indicators usually determined by full-scale tests. The difference lies in the ability to fully control the course of virtual testing, recording any parameters of the vehicle movement, taking into account the “human factor”, as well as complete safety of the experiment. Purpose of research. The purpose of this work is to create a mathematical model of the dynam-ics of a wheeled vehicle, suitable for use in such a complex of full-scale mathematical modeling and assessment of the load of transmission units in conditions close to real operation. Methodology and methods. The proposed model is based on the existing model of the dynamics of a wheeled vehicle developed at Bauman Moscow State Technical University. Within the framework of the model, the dynamics of a vehicle is described as a plane motion of a rigid body in a horizontal plane. The principle of possible displacements is applied to determine the normal reac-tions of the bearing surface. The interaction of the wheel with the ground in the plane of the support base is described using an approach based on the “friction ellipse” concept. To enable the driver and operator of the full-scale mathematical modeling complex to drive a virtual vehicle in “real time” mode, the mathematical model is supplemented with a control system that communicates between the control parameter set by the driver by pressing the accelerator and brake pedals and the control actions of the vehicle's transmission units, such as: an electric machine, an internal combustion en-gine, a hydrodynamic retarder and a brake system. The article presents a block diagram of the de-veloped control algorithm, as well as approbation of the system's operation in a complex of full-scale mathematical modeling. Results and scientific novelty. A mathematical model of the dynamics of a wheeled vehicle was developed. It opens up wide possibilities for studying the modes of operation of the “driver-vehicle-environment” system in “real time”, using a complex of full-scale mathematical modeling. Practical significance. A mathematical model of the dynamics of a wheeled vehicle was devel-oped. It is supplemented with an algorithm for the distribution of traction / braking torques between the transmission units, which provide a connection between the driver's pressing on the accelerator / brake pedal and the control parameters of each of the units.

Use of Fiber-Optic Information To Detect and Investigate the Gas-in-Riser Phenomenon

2021 ◽  
pp. 1-18
Author(s):  
Otto L. A. Santos ◽  
Wesley C. Williams ◽  
Jyotsna Sharma ◽  
Mauricio A. Almeida ◽  
Mahendra K. Kunju ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Fiber Optic ◽  
Research Effort ◽  
Pressure Sensors ◽  
Full Scale ◽  
Petroleum Engineering ◽  
Gas Migration ◽  
Two Phase ◽  
Engineering Research ◽  
Experimental Runs

Summary A potential application of optical fiber technologies in the well control domain is to detect the presence of gas and to unfold the gas dynamics inside marine risers (gas-in-riser). Detecting and monitoring gas-in-riser has become more relevant now when considering the application of managed pressure drilling operations in deep and ultradeep waters that may allow for a controlled amount of gas inside the riser. This application of distributed fiber-optic sensing (DFOS) is currently being evaluated at Louisiana State University (LSU) as part of a gas-in-riser research project granted by the National Academies of Sciences, the Gulf Research Program (GRP). Thus, the main objective of this paper is to present and discuss the use of DFOS and downhole pressure sensors to detect and track the gas position inside a full-scale test well during experimental runs conducted at LSU. The other objectives of this work are to show experimental findings of gas migration in the closed test well and to present the adequacy of a mathematical model experimentally validated to match the data obtained in the experimental trials. As a part of this research effort, an existing test well at the LSU Petroleum Engineering Research and Technology Transfer Laboratory (PERTT Lab) was recompleted and instrumented with fiber-optic sensors to continuously collect data along the wellbore and with four pressure and temperature downhole gauges to record those parameters at four discrete depths. A 2⅞-in. tubing string, with its lower end at a depth of 5,026 ft, and a chemical line to inject nitrogen at the bottom of the hole were also installed in the well. Seven experimental runs were performed in this full-scale apparatus using fresh water and nitrogen to calibrate the installed pieces of equipment, to train the crew of researchers to run the tests, to check experimental repeatability, and to obtain experimental results under very controlled conditions because water and nitrogen have well-defined and constant properties. In five runs, the injected gas was circulated out of the well, whereas in two others, the gas was left inside the closed test well to migrate without circulation. This paper presents and discusses the results of four selected runs. The experimental runs showed that fiber-optic information can be used to detect and track the gas position and consequently its velocity inside the marine riser. The fiber-optic data presented a very good agreement with those measured by the four downhole pressure gauges, particularly the gas velocity. The gas migration experiments produced very interesting results. With respect to the mathematical model based on the unsteady-state flow of a two-phase mixture, the simulated results produced a remarkable agreement with the fiber-optic, surface acquisition system and the downhole pressure sensors data gathered from the experimental runs.

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