Weight Optimized Structural and Acoustic Actuators for the Control of Sound Transmission Into Rocket Payload Compartments

2004 ◽  
Author(s):  
Marty Johnson ◽  
Ozer Sacarcelik ◽  
Tony Harris
Keyword(s):  
Rare Earth ◽  
Active Control ◽  
Sound Transmission ◽  
Degree Of Freedom ◽  
Main Concern ◽  
Maximum Output ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Acoustic Space ◽  
Two Degree Of Freedom

The reduction of sound transmission into rocket payload compartments is a challenging application for active control due to the broadband nature of the disturbance, the large structural and acoustic space and the very high acoustic levels required. The exterior acoustic field that drives the payload fairing at liftoff is typically in the order of 145dB and the active control system must be able to counteract this high drive level using lightweight actuators. This paper is concerned with the development of structural and acoustic actuators for this application with the emphasis on maximum output level in the 60–200Hz bandwidth for a given actuator weight. The electromagnetic structural actuators are based on powerful rare earth magnets in a two degree of freedom arrangement. It is shown that a two degree of freedom arrangement allows the output in the bandwidth of interest to be increased over a simple one degree of freedom arrangement. The design is termed a distributed active vibration absorber or DAVA as the second degree of freedom is provided by a light and distributed foam element that allows easy attachment and low stress concentration on the structure. The two degree of freedom arrangement also acts as a natural low pass filter to naturally remove unwanted spillover at higher frequencies. The acoustic component is also based on powerful rare earth magnets, however the two degree of freedom arrangement used for the structural actuator is no longer of interest. The main concern is in the reduction of the speaker and cabinet weight. It is shown that careful design of the speaker and cabinet can lead to large reductions in weight without loss of performance. Data taken from an active control experiment on a large composite cylinder, coupled with data from the characterization of the actuators will be used to determine the total actuator weight needed for control in a typical launch environment.

scholarly journals A One-Dimensional Magnetic Chip with a Hybrid Magnetosensor and a Readout Circuit

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Guo-Ming Sung ◽  
Hsin-Kwang Wang ◽  
Leenendra Chowdary Gunnam
Keyword(s):  
Field Effect Transistors ◽  
Oxide Semiconductor ◽  
Instrumentation Amplifier ◽  
Maximum Output ◽  
Hall Voltage ◽  
Readout Circuit ◽  
Pass Filter ◽  
Low Pass Filter ◽  
One Dimensional ◽  
Macro Model

This work presents a one-dimensional magnetic chip composed of a hybrid magnetosensor and a readout circuit, which were fabricated with 0.18 μm 1P6M CMOS technology. The proposed magnetosensor includes a polysilicon cross-shaped Hall plate and two separated metal-oxide semiconductor field-effect transistors (MOSFETs) to sense the magnetic induction perpendicular to the chip surface. The readout circuit, which comprises a current-to-voltage converter, a low-pass filter, and an instrumentation amplifier, is designed to amplify the output Hall voltage with a gain of 43 dB. Furthermore, a SPICE macro model is proposed to predict the sensor’s performance in advance and to ensure sufficient comprehension of the magnetic mechanism of the proposed magnetosensor. Both simulated and measured results verify the correctness and flexibility of the proposed SPICE macro model. Measurements reveal that the maximum output Hall voltage VH, the optimum current-related magnetosensitivity SRI, the optimum voltage-related magnetosensitivity SRV, the averaged nonlinearity error NLE, and the relative bias current Ibias are 4.381 mV, 520.5 V/A·T, 40.04 V/V·T, 7.19%, and 200 μA, respectively, for the proposed 1-D magnetic chip with a readout circuit of 43 dB. The averaged NLE is small at high magnetic inductions of ±30 mT, whereas it is large at low magnetic inductions of ±30 G.

Transmissibilities of Two-Degree-of-Freedom Systems for Semi-Active Vibration Control

Aerospace ◽  
2006 ◽  
Author(s):  
H. F. Lam ◽  
W. H. Liao
Keyword(s):  
Control Systems ◽  
Active Control ◽  
Transfer Functions ◽  
Active Vibration Control ◽  
Degree Of Freedom ◽  
Reference Systems ◽  
Active Systems ◽  
Active Vibration ◽  
Equivalent Systems ◽  
Two Degree Of Freedom

Transmissibilities for two-degree-of-freedom (2DoF) passive systems have been extensively investigated in the past. However, for semi-active control systems, the transmissibilities are rarely analyzed. The expressions of non-dimensional transmissibilities for the semi-active control systems are not found. There are no closed-form transfer functions for general semi-active control systems. The control algorithms for semi-active systems need to be specified first. Therefore, three reference systems (skyhook, groundhook, and their hybrid) are proposed. These equivalent systems are the references for the semi-active control systems to achieve. In this paper, the 2DoF skyhook, groundhook and hybrid systems for semi-active control are studied. The displacement and acceleration transmissibilities of those three reference systems are formulated and analyzed. Their transmissibilities are also compared with the passive system. Each of reference systems is classified as Ideal and Non-Ideal systems. The differences between the Ideal and Non-Ideal systems are also discussed. The optimal systems and their corresponding parameters are identified.

scholarly journals Tunable Lossy and Lossless Grounded Inductors Using Minimum Active and Passive Components

2021 ◽  
Vol 11 (3) ◽  
pp. 171-190
Author(s):  
Tapas Kumar Paul ◽  
Suvajit Roy ◽  
Radha Raman Pal
Keyword(s):  
Power Dissipation ◽  
Maximum Output ◽  
Passive Components ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Transconductance Amplifier ◽  
Low Pass ◽  
Component Matching ◽  
Band Pass ◽  
Electronically Tunable

In this contribution, nine new Grounded Inductance Simulators (GISs) using a single Multiple-Output Current Controlled Current Conveyor Transconductance Amplifier (MO-CCCCTA) and one grounded capacitor are proposed. Among them, two are lossless types and seven are lossy types. The use of a single grounded capacitor makes the circuits suitable for fabrication. All the proposed circuits are electronically tunable through the bias currents of MO-CCCCTA. Furthermore, no component matching conditions are needed for realizing them. The designed circuits are verified through PSPICE simulator with ± 0.9 V power supply. The simulation results show that for all the proposed circuits: maximum operating frequencies are about 12 MHz, power dissipation is less than 0.784 mW, Total Harmonic Distortions (THDs) are under 8.09%, and maximum output voltage noise at 1 MHz frequency is 14.094 nV/√Hz. To exhibit the workability of the proposed circuits, they are used to design band-pass, low-pass filter, parallel RLC resonator, and parasitic inductance cancelator.

Gas density does not affect pulmonary acoustic transmission in normal men

1995 ◽  
Vol 78 (3) ◽  
pp. 928-937 ◽  
Author(s):  
M. Mahagnah ◽  
N. Gavriely
Keyword(s):  
Chest Wall ◽  
Power Spectra ◽  
Sound Transmission ◽  
Wide Band ◽  
Modern Technology ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Gas Density ◽  
Pulmonary System ◽  
Exponential Decline

Fremitus, the transmission of sound and vibration from the mouth to the chest wall, has long been used clinically to examine the pulmonary system. Recently, modern technology has become available to measure the acoustic transfer function (TF) and transit times (TT) of the pulmonary system. Because sound speed is inversely proportional to the square root of gas density in free gas, but not in porous media, we measured the effect of air and Heliox (80% He-20% O2) breathing on pulmonary sound transmission in six healthy subjects to investigate the mechanism of sound transmission. Wide-band noise (75–2,000 Hz) was “injected” into the mouth and picked up over the trachea and chest wall. The averaged power spectra, TF, phase, and coherence were calculated using a fast Fourier transform-based algorithm. The phase data were used to calculate TT as a function of frequency. TF was found to consist of a low-pass filter property with essentially flat transmitted energy to 300 Hz and exponential decline to 600 Hz at the anterior right upper lobe (CR) and flat transmission to 100 Hz with exponential decline to 150 Hz at the right posterior base (BR). TF was not affected by breathing Heliox. The average TT values, calculated from the slopes of the averaged phase, were 1.5 +/- 0.5 ms for trachea to CR and 5.2 +/- 0.5 ms for trachea to BR transmission during air breathing. During Heliox breathing, the values of TT were 1.5 +/- 0.5 ms and 4.9 +/- 0.5 ms from the trachea to CR and from the trachea to BR locations, respectively. These results suggest that sound transmission in the respiratory system is dominated by wave propagation through the parenchymal porous structure.

scholarly journals Deceleration time of projectile penetration/perforation into a concrete target: Experiment and discussions

2018 ◽  
Vol 22 (1) ◽  
pp. 112-125 ◽  
Author(s):  
Yong Peng ◽  
Hao Wu ◽  
Qin Fang ◽  
Ziming Gong
Keyword(s):  
Rigid Body ◽  
Cutoff Frequency ◽  
Main Concern ◽  
Time Data ◽  
Complex Signals ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Reinforced Concrete Slabs ◽  
Time Histories ◽  
Deceleration Time

Deceleration time histories of the 25.3 mm diameter, 428 g projectile penetration/perforation into 41 MPa reinforced concrete slabs with thicknesses of 100, 200, and 300 mm, are discussed. An ultra-high g small-caliber deceleration data recorder with a diameter of 18 mm is employed to digitize and record the acceleration during launch in the barrel, as well as the deceleration during penetration or perforation into targets. The accelerometer mounted in the data recorder measures rigid-body projectile deceleration as well as structural vibrations. To validate these complex signals, a validation approach for the accuracy of the recorded deceleration time data is proposed based on frequency characteristic analyses and signal integrations, and three sets of whole-range deceleration time data are validated. As the deceleration of the rigid-body projectile is the main concern, a signal processing approach is further given to obtain the rigid-body deceleration data, that is, using a low-pass filter to remove the high-frequency responses associated with vibrations of the projectile case and the internal supporting structure. The first valley frequency from the spectrum analysis is determined to be the critical cutoff frequency. To verify the accuracies of the theoretical model and the numerical simulation in predicting projectile motion time histories, theoretical projectile penetration/perforation deceleration time models are given and numerical simulations are performed. The predicted projectile time histories consist well with the validated deceleration time test data, as do their corresponding velocity and displacement time curves.

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