High-Speed Ground Transport—A Stochastic Model of Track Roughness and Misalignment

1978 ◽  
Vol 20 (3) ◽  
pp. 143-148 ◽  
Author(s):  
L. A. Balzer
Keyword(s):  
Mathematical Model ◽  
Stochastic Model ◽  
High Speed ◽  
Numerical Data ◽  
Test Track ◽  
Transport Vehicle ◽  
Computer Generation

One of the significant disturbances to a tracked hovercraft or any other high-speed ground transport vehicle is the roughness of the guideway surface together with misalignment of the guideway structure itself. Existing methods of describing this roughness and misalignment are reviewed and their shortcomings noted. A description is proposed which is valid in both statistical and wavelength-amplitude domains. Numerical data from the Tracked Hovercraft Ltd test track at Earith are analysed and a mathematical model proposed for a typical commercial H.S.G.T. guideway. A method of computer generation of typical roughness profiles is discussed.

scholarly journals Investigation of the Stochastic Modeling of COVID-19 with Environmental Noise from the Analytical and Numerical Point of View

Mathematics ◽  
2021 ◽  
Vol 9 (23) ◽  
pp. 3122
Author(s):  
Shah Hussain ◽  
Elissa Nadia Madi ◽  
Hasib Khan ◽  
Sina Etemad ◽  
Shahram Rezapour ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Stochastic Model ◽  
Numerical Scheme ◽  
Computational Analysis ◽  
Reproduction Number ◽  
Numerical Data ◽  
Point Of View ◽  
Deterministic Models ◽  
The Future ◽  
Future Prediction

In this article, we propose a novel mathematical model for the spread of COVID-19 involving environmental white noise. The new stochastic model was studied for the existence and persistence of the disease, as well as the extinction of the disease. We noticed that the existence and extinction of the disease are dependent on R0 (the reproduction number). Then, a numerical scheme was developed for the computational analysis of the model; with the existing values of the parameters in the literature, we obtained the related simulations, which gave us more realistic numerical data for the future prediction. The mentioned stochastic model was analyzed for different values of σ1,σ2 and β1,β2, and both the stochastic and the deterministic models were compared for the future prediction of the spread of COVID-19.

scholarly journals Aerodynamics of inclined cylindrical bodies free-flying in a hypersonic flowfield

2021 ◽  
Vol 62 (9) ◽  
Author(s):  
Patrick M. Seltner ◽  
Sebastian Willems ◽  
Ali Gülhan ◽  
Eric C. Stern ◽  
Joseph M. Brock ◽  
...  
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Numerical Data ◽  
Static Stability ◽  
Free Flight ◽  
Aerodynamic Coefficients ◽  
Flow Topology ◽  
Motion Data ◽  
Continuous Rotation ◽  
German Aerospace

Abstract The influence of the flight attitude on aerodynamic coefficients and static stability of cylindrical bodies in hypersonic flows is of interest in understanding the re/entry of space debris, meteoroid fragments, launch-vehicle stages and other rotating objects. Experiments were therefore carried out in the hypersonic wind tunnel H2K at the German Aerospace Center (DLR) in Cologne. A free-flight technique was employed in H2K, which enables a continuous rotation of the cylinder without any sting interferences in a broad angular range from 0$$^{\circ }$$ ∘ to 90$$^{\circ }$$ ∘ . A high-speed stereo-tracking technique measured the model motion during free-flight and high-speed schlieren provided documentation of the flow topology. Aerodynamic coefficients were determined in careful post-processing, based on the measured 6-degrees-of-freedom (6DoF) motion data. Numerical simulations by NASA’s flow solvers Cart3D and US3D were performed for comparison purposes. As a result, the experimental and numerical data show a good agreement. The inclination of the cylinder strongly effects both the flowfield and aerodynamic loads. Experiments and simulations with concave cylinders showed marked difference in aerodynamic behavior due to the presence of a shock–shock interaction (SSI) near the middle of the model. Graphic abstract

scholarly journals Stochastic and deterministic mathematical model of cholera disease dynamics with direct transmission

2020 ◽  
Vol 2020 (1) ◽  
Author(s):  
Getachew Teshome Tilahun ◽  
Woldegebriel Assefa Woldegerima ◽  
Aychew Wondifraw
Keyword(s):  
Mathematical Model ◽  
Stochastic Model ◽  
Deterministic Model ◽  
Equilibrium Points ◽  
Invariant Solution ◽  
Stochastic Approach ◽  
Disease Dynamics ◽  
Treatment Rate ◽  
Invariant Region ◽  
Contact Transmission

AbstractIn this paper we develop a stochastic mathematical model of cholera disease dynamics by considering direct contact transmission pathway. The model considers four compartments, namely susceptible humans, infectious humans, treated humans, and recovered humans. Firstly, we develop a deterministic mathematical model of cholera. Since the deterministic model does not consider the randomness process or environmental factors, we converted it to a stochastic model. Then, for both types of models, the qualitative behaviors, such as the invariant region, the existence of a positive invariant solution, the two equilibrium points (disease-free and endemic equilibrium), and their stabilities (local as well as global stability) of the model are studied. Moreover, the basic reproduction numbers are obtained for both models and compared. From the comparison, we obtained that the basic reproduction number of the stochastic model is much smaller than that of the deterministic one, which means that the stochastic approach is more realistic. Finally, we performed sensitivity analysis and numerical simulations. The numerical simulation results show that reducing contact rate, improving treatment rate, and environmental sanitation are the most crucial activities to eradicate cholera disease from the community.

Prediction of Surface Roughness in Compressed Air Jet Assisted High Speed End Milling of Silicon Using Diamond Coated Tools

2012 ◽  
Vol 576 ◽  
pp. 41-45
Author(s):  
A.K.M. Nurul Amin ◽  
M.A. Mahmud ◽  
M.D. Arif
Keyword(s):  
Mathematical Model ◽  
Surface Roughness ◽  
Surface Finish ◽  
High Speed ◽  
End Milling ◽  
Silicon Wafers ◽  
Compressed Air ◽  
Machining Parameters ◽  
High Quality ◽  
Ductile Mode

The majority of semiconductor devices are made up of silicon wafers. Manufacturing of high-quality silicon wafers includes numerous machining processes, including end milling. In order to end mill silicon to a nano-meteric surface finish, it is crucial to determine the effect of machining parameters, which influence the machining transition from brittle to ductile mode. Thus, this paper presents a novel experimental technique to study the effects of machining parameters in high speed end milling of silicon. The application of compressed air, in order to blow away the chips formed, is also investigated. The machining parameters’ ranges which facilitate the transition from brittle to ductile mode cutting as well as enable the attainment of high quality surface finish and integrity are identified. Mathematical model of the response parameter, the average surface roughness (Ra) is subsequently developed using RSM in terms of the machining parameters. The model was determined, by Analysis of Variance (ANOVA), to have a confidence level of 95%. The experimental results show that the developed mathematical model can effectively describe the performance indicators within the controlled limits of the factors that are being considered.

Research on the Performance Simulation of the Transmission System of Loader with Secondary Regulating Technique

2010 ◽  
Vol 426-427 ◽  
pp. 299-302
Author(s):  
Fa Ye Zang
Keyword(s):  
Mathematical Model ◽  
Fuzzy Control ◽  
Energy Saving ◽  
High Speed ◽  
Transmission System ◽  
Performance Simulation ◽  
Constant Torque ◽  
Braking Torque ◽  
The Mathematical Model ◽  
Inertial Energy

Based on deeply analyzing the working principles and energy-saving theory of loader secondary regulating transmission system, regenerating the transmission system’s inertial energy by controlling constant torque was put forward. Considering large changes of the parameters of the transmission system and its non-linearity, a fuzzy control was adopted to control the transmission system, and the mathematical model of the system was established, then the simulations of the performance of the transmission system has been conducted. The conclusion was made that the inertial energy can be reclaimed and reused in the system by the application of the secondary regulation technology, and braking by controlling constant torque is stable, it can ensure the security of braking at high speed and also permits changing the efficiency of recovery by changing the braking torque. The system’s power has been reduced and energy saving has been achieved.

SUBSTANTIATION OF OPTIMAL PARAMETERS AND DEVELOPMENT OF HIGH-TEMPERATURE STERILIZATION MODES FOR COMPOTE FROM PEARS IN HEATED AIR FLOW

2020 ◽  
Author(s):  
М.Э. Ахмедов ◽  
А.Ф. Демирова ◽  
Г.И. Касьянов ◽  
Ю.Ф. Росляков ◽  
М.М. Рахманова
Keyword(s):  
Mathematical Model ◽  
High Temperature ◽  
High Speed ◽  
Heat Transfer Fluid ◽  
Initial Product ◽  
Hot Air ◽  
Heated Air ◽  
Sterilization Process ◽  
Thermal Sterilization ◽  
Heat Carriers

Разработаны новые режимы стерилизации компота из груш в стеклотаре СКО 1-82-1000 с использованием высокотемпературных скоростных теплоносителей. Получена математическая модель расчета продолжительности процесса стерилизации в зависимости от параметров теплоносителя. Для получения математической модели использован метод математического планирования эксперимента. Предложен технологический прием ускоренной стерилизации компота из груш в стеклобанке объемом 1 дм3. Разработаны новые режимы тепловой обработки (стерилизации) компота из груш в стеклобанке 1-82-1000 при различных параметрах горячего воздуха и разных начальных температурах продукта, °С: 70, 80, 85 и 90. Наименьшая продолжительность процесса тепловой стерилизации достигнута при скорости теплоносителя 7,5 м/с при начальной температуре продукта 90°С. New modes of sterilization of compote from pears in glass containers of SKO 1-82-1000 using high-temperature high-speed heat carriers have been developed. A mathematical model for calculating the duration of the sterilization process depending on the parameters of the heat carrier is obtained. To obtain a mathematical model, we used the method of mathematical planning of the experiment. A technological method for accelerated sterilization of pear compote in a glass jar with a volume of 1 dm3 is proposed. The research made it possible to develop new modes of heat treatment (sterilization) of compote from pears in a glass jar 1-82-1000 at different parameters of hot air and different initial temperatures of the product, °C: 70, 80, 85 and 90. The shortest duration of the thermal sterilization process is achieved at the heat transfer fluid speed of 7,5 m/s at the initial product temperature of 90°C.

Increasing the mobility of a high-speed tracked vehicle based on a controlled skid algorithm

2020 ◽  
pp. 29-33
Author(s):  
S. V. Kondakov ◽  
O.O. Pavlovskaya ◽  
I.D. Ivanov ◽  
A.R. Ishbulatov
Keyword(s):  
Mathematical Model ◽  
Dynamic Stability ◽  
Simulation Modeling ◽  
Automatic System ◽  
High Speed ◽  
Control Algorithm ◽  
Loss Of Stability ◽  
Tracked Vehicle ◽  
Hydrostatic Transmission ◽  
The Mathematical Model

A method for controlling the curvilinear movement of a high-speed tracked vehicle in a skid without loss of stability is proposed. The mathematical model of the vehicle is refined. With the help of simulation modeling, a control algorithm is worked out when driving in a skid. The effectiveness of vehicle steering at high speed outside the skid is shown. Keywords: controlled skid, dynamic stability, steering pole displacement, hydrostatic transmission, automatic system, fuel supply. [email protected]

Study on Mathematical Model of High Speed Milling Force for Plastic Mold Steel 3Cr2Mo

2011 ◽  
Vol 291-294 ◽  
pp. 710-714
Author(s):  
Jun Min Xiao ◽  
Ying Xu
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
High Speed ◽  
High Hardness ◽  
Milling Force ◽  
High Speed Milling ◽  
Engineering Requirement ◽  
Practical Engineering ◽  
Cad Cam ◽  
Plastic Mold

Mold steel 3Cr2Mo has been used widely in manufacturing of plastic mold formed parts, owing to fine mechanical properties. However, it is also very difficult to cut mold formed parts of steel 3Cr2Mo due to high hardness. Ordinary NC cutting method of steel 3Cr2Mo is unable to relate to modern mold manufacturing due to bad cutting property, so it is extremely significant for improving cutting property of steel 3Cr2Mo to study the high speed milling technology. On the basis of improving the traditional cutting force formula, the mathematical model of high speed milling force for steel 3Cr2Mo was derived and solved by using the experimental data and constructing matrix equation based on MATLAB software. Comparing with experimental data, the error of mathematical model of high speed milling force could be controlled within 6 percent. Due to high precision the model of high speed milling force can meet practical engineering requirement and has great value in the fields of CAD/CAM/CAE.

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