LOW-FREQUENCY IMPEDANCE OF ANISOTROPIC ENGINEERING DESIGN

Akustika ◽  
2021 ◽  
pp. 262
Author(s):  
Sergey A. Rykov ◽  
Irina Kudryavtseva ◽  
Sergey V. Rykov
Keyword(s):  
Mathematical Model ◽  
Engineering Design ◽  
Experimental Research ◽  
Great Influence ◽  
Low Frequency ◽  
Inhomogeneous Distribution ◽  
Anisotropic Structure ◽  
Frequency Range ◽  
Anisotropic Structures ◽  
The Mathematical Model

The results of theoretical and experimental research of the impedance of an anisotropic structure in the low frequency range are presented. It is shown that taking into account the inhomogeneous distribution of mass along the length of the structure has a great influence on the value of the impedance of an anisotropic structure. Based on the results obtained in the mathematical model, expressions are proposed for calculating the impedances of anisotropic structures in the low frequency range.

A Study on Exhaust Muffler Using Counter-Phase Counteract

2014 ◽  
Vol 986-987 ◽  
pp. 810-813
Author(s):  
Ying Li Shao
Keyword(s):  
Mathematical Model ◽  
Experimental Validation ◽  
Noise Source ◽  
Low Frequency ◽  
Frequency Noise ◽  
Expansion Chamber ◽  
Band Noise ◽  
Exhaust Noise ◽  
Perforated Pipe ◽  
The Mathematical Model

The exhaust noise, which falls into low-frequency noise, is the dominant noise source of a diesel engines and tractors. The traditional exhaust silencers, which are normally constructed by combination of expansion chamber, and perforated pipe or perforated board, are with high exhaust resistance, but poor noise reduction especially for the low-frequency band noise. For this reason, a new theory of exhaust muffler of diesel engine based on counter-phase counteracts has been proposed. The mathematical model and the corresponding experimental validation for the new exhaust muffler based on this theory were performed.

Buffer Groove Design of Continuous Rotary Electro-Hydraulic Servo Motor Used in Simulator

2010 ◽  
Vol 37-38 ◽  
pp. 234-237
Author(s):  
Xiao Jing Wang ◽  
Jun Peng Shao ◽  
Guang Bin Yu
Keyword(s):  
Mathematical Model ◽  
Pressure Gradient ◽  
Experimental Research ◽  
Pressure Field ◽  
Structure Design ◽  
Cavity Pressure ◽  
Servo Motor ◽  
Pressure Impact ◽  
Hydraulic Servo ◽  
The Mathematical Model

In order to improve the low speed stationary of continuous rotary electro-hydraulic servo motor and avoid the pressure impact in the sealed cavity during the oil distributing, this paper designed the shape of buffer groove, established the mathematical model of pressure gradient, and analyzed change law of sealed cavity pressure gradient under different dimension of buffer groove. The pressure field distribution of sealed cavity was studied in certain radial and axial gap, and it is validated the dimension of buffer groove is rational, which lays foundation for structure design and experimental research of large displacement servo motor.

Experimental Research on Performance of Heat Transfer and Pressure Drop for Primary Surface Recuperator With Mini Channels

2011 ◽  
Author(s):  
Hugen Ma ◽  
Hui Gao ◽  
Wenjing Tu
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Pressure Drop ◽  
Experimental Research ◽  
Transfer Factor ◽  
Flow And Heat Transfer ◽  
Good Consistency ◽  
Mini Channels ◽  
Performance Of Heat Transfer ◽  
The Mathematical Model

Based on the single blow technique, experimental research was conducted for the performance of heat transfer and flow drop for six test cores with cross corrugated (CC) or corrugated undulated (CU) primary surfaces for different geometries. After the mathematical model was established for heat transfer under the condition of single blow, a matching numerical solution was obtained for different NTU. The correlations of hear transfer factor j and friction factor f were obtained for three types of cross corrugated primary surfaces (crossed angle 45∼75°) with a range of Re = 120∼800 and three types of corrugated undulated primary surfaces (crossed angle 52.5∼67.5°) with a range of Re = 200∼1200. Hydraulic diameters of all heat transfer surfaces are from 1.2∼1.48mm. Analysis on the flow and heat transfer for cross corrugated and corrugated undulated primary surfaces was made based on the comprehensive evaluating factor j/f. The experimental results were compared to references with good consistency. The regressive errors of correlations were less than 16%.

Theoretical Modelling of the Particle Damper

2013 ◽  
Vol 726-731 ◽  
pp. 3128-3131
Author(s):  
Zhao Wang Xia ◽  
Yuan Yuan Fang
Keyword(s):  
Mathematical Model ◽  
Low Frequency ◽  
High Amplitude ◽  
Theoretical Modelling ◽  
Impact Damper ◽  
Optimum Parameters ◽  
Theoretical Investigations ◽  
Particle Damping ◽  
The Mathematical Model ◽  
Base Structure

Particle damping is a method for improving damping of a dynamic system by means of energy dissipation due to repeated collisions of a free mass on the base structure. In this paper, the theoretical investigations carried out to study and characterize damping with respect to the level of base excitation. The mathematical model consists of a particle damping system. The response obtained from the mathematical model for the drum brake and paticle damper. Here the effect of particle damping is studied for low frequency and high amplitude excitation. Optimum parameters are determined for design of impact damper based on the mathematical model. A good match is obtained by theoretical results.

scholarly journals Improving the Dynamic Characteristics of Precision Lathes Used in the Repair of Agricultural Machinery

2021 ◽  
pp. 36-39
Author(s):  
D.E. Molochnikov ◽  
◽  
R.Sh. Halimov ◽  
N.P. Ayugin ◽  
I.R. Salakhutdinov ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Dynamic Characteristics ◽  
Low Frequency ◽  
Frequency Component ◽  
Honeycomb Structure ◽  
Friction Unit ◽  
Agricultural Machinery ◽  
Longitudinal Vibrations ◽  
Model Of Friction ◽  
The Mathematical Model

A model of a friction unit of a lathe in the form of a thin layer of material of a honeycomb structure is described to determine the dynamic characteristics of a movable carriage to guide joint. The analysis of the mathematical model of friction for different sliding pairs with varying load and sliding speed is performed. It is shown that the presence of an abrasive impurity in the lubrication of the guide enhances the effect of the low-frequency component of the carriage vibrations on the dynamics of the machine tool and the presence of pockets for retaining the lubricant in the joint of the guide makes it possible to reduce the amplitude of the longitudinal vibrations of the carriage to 30-50 %.

TECHNIQUE OF APPLICATION FOR PROCESSING OF LOW PASS FILTER LF SIGNALS

10.12737/7905 ◽  
2015 ◽  
Vol 7 (4) ◽  
pp. 35-38
Author(s):  
Табаков ◽  
Yu. Tabakov ◽  
Лавлинский ◽  
V. Lavlinskiy
Keyword(s):  
Mathematical Model ◽  
Block Diagram ◽  
Low Frequency ◽  
Frequency Signal ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass ◽  
The Mathematical Model ◽  
40 Hz

The article includes a block diagram and the mathematical model for low pass filter designed for processing low frequency signal with a frequency of 10-40 Hz in order of eliminate various noises and interference.

Developing of an Active Hydraulic Bushing for Multi-Displacement Engines

2006 ◽  
Author(s):  
S. Arzanpour ◽  
M. F. Golnaraghi
Keyword(s):  
Mathematical Model ◽  
Research Effort ◽  
Dynamic Stiffness ◽  
Excitation Frequency ◽  
Feedback Signal ◽  
Frequency Range ◽  
Engine Mount ◽  
Isolation Requirements ◽  
Stiffness And Damping ◽  
The Mathematical Model

This paper outlines the development of an active hydraulic bushing system for the Multi Displacement System (MDS) Engine isolation problems. The prior art research effort on engine mounts and bushings has so far focused on the improvement of the mount dynamic stiffness properties. The optimum dynamic stiffness and damping of the engine bushings is both frequency and amplitude dependent. While these systems are available commercially, they have many limitations, particularly for new vehicle models and new engine generations such as MDS engines. A suitable isolator for an MDS engine should be half as stiff in the operating frequency range of the engine (5-70 Hz) in MDS mode, while showing the same performance as conventional hydraulic bushings in normal engine operations. Passive hydraulic bushings are not capable of meeting the isolation requirements discussed for the MDS engines because they are not adjustable. There are different parameters which contribute to the dynamic stiffness response of a hydraulic bushing. Some of those parameters are defined by passive components such as rubber stiffness and damping. However, other parameters such as the pressure inside the bushing can be altered actively. The mathematical model of a conventional hydraulic bushing is given in this paper. The model suggests that the pressure inside the bushing has a significant role in the dynamic stiffness response of the bushing. As a result, an additional pumping chamber is introduced as a solution. The pump is utilized to adjust the pressure inside the bushing based on the engine excitation frequency. This pump can be driven by proper actuators which can produce pressure differences in the frequency range of interest. The mechanical and mathematical model of such a system is derived using a simplified linear model. This technique enables the engine mount to adjust to the dynamic stiffness characteristics by applying a feedback signal to the actuator. The feedback signal to the actuator is also obtained using the mathematical model for many required cases yet adjustable for others. The response of the system is discussed in frequency domains. The simulation results prove that the additional pumping chamber can effectively be used to control the stiffness of the conventional hydraulic bushings.

scholarly journals A non-linear mathematical model for the X-ray variability of the microquasar GRS 1915+105 – III. Low-frequency quasi-periodic oscillations

2020 ◽  
Vol 497 (1) ◽  
pp. 405-415
Author(s):  
E Massaro ◽  
F Capitanio ◽  
M Feroci ◽  
T Mineo
Keyword(s):  
Mathematical Model ◽  
Equilibrium Points ◽  
Low Frequency ◽  
Input Function ◽  
Power Density Spectrum ◽  
Periodic Oscillations ◽  
Density Spectrum ◽  
X Ray ◽  
Almost All ◽  
The Mathematical Model

ABSTRACT The X-ray emission from the microquasar GRS 1915+105 shows, together with a very complex variability on different time-scales, the presence of low-frequency quasi-periodic oscillations (LFQPOs) at frequencies lower than ∼30 Hz. In this paper, we demonstrate that these oscillations can be consistently and naturally obtained as solutions of a system of two ordinary differential equations, which is able to reproduce almost all variability classes of GRS 1915+105. We modified the Hindmarsh–Rose model and obtained a system with two dynamical variables x(t), y(t), where the first one represents the X-ray flux from the source, and an input function J(t), whose mean level J0 and its time evolution is responsible of the variability class. We found that for values of J0 around the boundary between the unstable and the stable interval, where the equilibrium points are of spiral type, one obtains an oscillating behaviour in the model light curve similar to the observed ones with a broad Lorentzian feature in the power density spectrum and, occasionally, with one or two harmonics. Rapid fluctuations of J(t), as those originating from turbulence, stabilize the LFQPOs, resulting in a slowly amplitude modulated pattern. To validate the model, we compared the results with real RXTE data, which resulted remarkably similar to those obtained from the mathematical model. Our results allow us to favour an intrinsic hypothesis on the origin of LFQPOs in accretion discs ultimately related to the same mechanism responsible for the spiking limit cycle.

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