scholarly journals Effect of Acoustic Shock on Submarine

2020 ◽  
Vol 10 (14) ◽  
pp. 4993
Author(s):  
Igor Korobiichuk ◽  
Viktorij Mel’nick ◽  
Volodimir Karachun
Keyword(s):  
Comparative Analysis ◽  
High Speed ◽  
Translational Motion ◽  
Underwater Vehicles ◽  
Compressed Air ◽  
Air Bubbles ◽  
Limiting Values ◽  
Real Medium ◽  
Limited Motion ◽  
The Ideal

The carried-out analysis of the dynamics of a submarine body’s translational motion affected by an acoustic shock in the ideal medium provides for the possibility to evaluate the physical properties of the medium and elastic properties of the external body of the submarine to the value of limited motion of a submersible vehicle. The results of analysis provide for the possibility to conduct a comparative analysis of the submersible vehicle’s translational motion affected by an acoustic shock, taking into account the peculiarities of the motion medium, or rather taking into account the viscosity of the real medium. In this work, evaluative measurements of the features of moving the layout of the submarine were carried out. The limiting values of the displacement of the layout of the submarine are established for the case of the presence of an external artificial diffuse disturbance. A fluid with air bubbles from a compressed air cylinder was used to create an artificial diffuse perturbation. Such conditions are possible with intensive local bombardment or the presence of other high-speed underwater vehicles involved in local underwater operations.

Parameter study and optimization design of a hat oblique tunnel portal

2021 ◽  
pp. 095440972110140
Author(s):  
Zijian Guo ◽  
Tanghong Liu ◽  
Wenhui Li ◽  
Yutao Xia
Keyword(s):  
High Speed ◽  
Optimization Design ◽  
Pareto Front ◽  
Optimization Problem ◽  
Optimization Method ◽  
Design Parameters ◽  
Parameter Study ◽  
Buffer Structure ◽  
Tunnel Entrance ◽  
The Ideal

The present work focuses on the aerodynamic problems resulting from a high-speed train (HST) passing through a tunnel. Numerical simulations were employed to obtain the numerical results, and they were verified by a moving-model test. Two responses, [Formula: see text] (coefficient of the peak-to-peak pressure of a single fluctuation) and[Formula: see text] (pressure value of micro-pressure wave), were studied with regard to the three building parameters of the portal-hat buffer structure of the tunnel entrance and exit. The MOPSO (multi-objective particle swarm optimization) method was employed to solve the optimization problem in order to find the minimum [Formula: see text] and[Formula: see text]. Results showed that the effects of the three design parameters on [Formula: see text] were not monotonous, and the influences of[Formula: see text] (the oblique angle of the portal) and [Formula: see text] (the height of the hat structure) were more significant than that of[Formula: see text] (the angle between the vertical line of the portal and the hat). Monotonically decreasing responses were found in [Formula: see text] for [Formula: see text] and[Formula: see text]. The Pareto front of [Formula: see text] and[Formula: see text]was obtained. The ideal single-objective optimums for each response located at the ends of the Pareto front had values of 1.0560 for [Formula: see text] and 101.8 Pa for[Formula: see text].

scholarly journals Study and Analysis of Anti Vibratory Passive and Active Methods Applied to Complex Mechanical System

2012 ◽  
Vol 7 (2) ◽  
Author(s):  
Cédric Lopez ◽  
François Malburet ◽  
André Barraco
Keyword(s):  
Experimental Study ◽  
Comparative Analysis ◽  
Mechanical System ◽  
High Speed ◽  
Test Bench ◽  
Minimization Method ◽  
Controlled System ◽  
Proper Frequency ◽  
Different Parts ◽  
Methods Of Control

This paper studies problematic of a mechanical system composed of different coupled parts submitted to a high speed shock and proposes analysis of anti vibratory passive and active methods based on an experimental and theoretical coupled approach. After a shock, different parts of the system oscillate. If one of them is excited at a particular frequency, such as its proper frequency, important oscillations appear and can lead to the deterioration of the system by introducing important stresses. In this paper, we propose an analysis in order to understand this kind of problem and what we can do to avoid it. Firstly, we discuss problematic and we expose the studied system. In a second time, we develop two approaches of modeling that allow us to understand the phenomenon by carrying out numerical simulations. Then cross checking of model is completed via experimental study on drop test bench. Passive minimization method of vibrations based on experimental and theoretical coupled approach is exposed. Finally, a comparative analysis of different methods of control and experimental results of controlled system are presented.

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.

scholarly journals The impact of rotational speed and water volume on textile translational motion in a front-loading washer

2018 ◽  
Vol 89 (16) ◽  
pp. 3401-3410 ◽  
Author(s):  
Hong Liu ◽  
R Hugh Gong ◽  
Pinghua Xu ◽  
Xuemei Ding ◽  
Xiongying Wu
Keyword(s):  
Residence Time ◽  
Rotational Speed ◽  
High Speed ◽  
Translational Motion ◽  
Processing System ◽  
Water Volume ◽  
Motion Path ◽  
Rotational Axis ◽  
Passive Region ◽  
The Impact

Textile motion in a front-loading washer has been characterized via video capturing, and a processing system developed based on image geometric moment. Textile motion significantly contributes to the mass transfer of the wash solution in porous materials, particularly in the radial direction (perpendicular to the rotational axis of the inner drum). In this paper, the velocity profiles and residence time distributions of tracer textiles have been investigated to characterize the textile dynamics in a front-loading washer. The results show that the textile motion varies significantly with the water volume and rotational speed, and that the motion path follows certain patterns. Two regions are observed in the velocity plots: a passive region where the textile moves up with low velocity and an active region where the textile falls down with relatively high speed. A stagnant area in the residence time profile is observed. This corresponds to the passive region in the velocity profile. The stagnant area affects the mechanical action, thus influencing washing efficiency and textile performance. The findings on textile dynamics will help in the development of better front-loading washers.

A Ballast System for Automated Deep-Sea Ascents

2016 ◽  
Author(s):  
Matthias Golz ◽  
Florin Boeck ◽  
Sebastian Ritz ◽  
Gerd Holbach
Keyword(s):  
Environmental Impact ◽  
Environmental Contamination ◽  
Pressure Vessel ◽  
Deep Sea ◽  
Underwater Vehicles ◽  
Compressed Air ◽  
Hydraulic Pump ◽  
Unmanned Underwater Vehicles ◽  
The Past ◽  
Set Up

The efforts to discover the world’s oceans — even in extremely deep-sea environments — have grown more and more in the past years. In this context, unmanned underwater vehicles play a central role. Underwater systems that are not tethered need to provide an apparatus to ensure a safe return to the surface. Therefore, positive buoyancy is required and can be achieved by either losing weight or expanding volume. A conservative method is the dropping of ballast weight. However, nowadays this method is not appropriate due to the environmental impact. This paper presents a ballast system for an automated ascent of a deep-sea seabed station in up to 6000 m depth. The ballast system uses a DC motor driven modified hydraulic pump and a compressed air auxiliary system inside a pressure vessel. With regard to the environmental contamination in case of a leakage, only water is used as ballast fluid. The modification of an ordinary oil-hydraulic radial piston pump and the set-up of the ballast system is introduced. Results from sea trials in the Atlantic Ocean are presented to verify the functionality of the ballast system.

scholarly journals COMPARATIVE ANALYSIS OF MODULATION SCHEMES USING ADAPTIVE EQUALIZATION AS FADING MITIGATION TECHNIQUE

2012 ◽  
pp. 25-31
Author(s):  
SABITA NAHATA ◽  
SUBRATA BHATTACHARYA
Keyword(s):  
Comparative Analysis ◽  
Data Transmission ◽  
High Speed ◽  
Signal To Noise Ratio ◽  
Multipath Fading ◽  
Symbol Error Rate ◽  
Adaptive Equalization ◽  
Modulation Scheme ◽  
Modulation Schemes ◽  
Mitigation Technique

Inter-symbol interference (ISI) due to multipath fading is a vital problem in high-speed wireless communication which restricts communication quality and capacity. Therefore, in addition to choosing a fading mitigation technique, it is also important to strategically select a modulation scheme for effective data transmission. Recent literature review on wireless standards, such as 3G and 4G indicates that QAM and QPSK are suitable choices for data transmission. In this paper, a comparative analysis on selected modulation schemes is performed in a fading environment. The mitigation of fading is done using adaptive equalization technique. Also, we show that the signal to noise ratio (SNR) is an important parameter to choose. It is observed that, even when an adaptive equalizer is used at the receiver, a very low SNR gives very high symbol error rate (SER). We derive some important conclusions from our simulation result: QPSK shows minimum SER, whereas 256-PSK and 256-PAM perform worse. Given its spectral efficiency and a low SER, the best choice is 256- QAM.

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