Dynamic Stability of Cylindrical Shells under Moving Loads by Applying Advanced Controlling Techniques—Part II: Using Piezo-Stack Control

The load acting on the actively controlled cylindrical shell under a transient pressure pulse propelling a moving mass (gun case) has been experimentally studied. The concept of using piezoelectric stack and stiffener combination is utilized for damping the tube wall radial and circumferential deforming vibrations, in the correct meeting location timing of the moving mass. The experiment was carried out by using the same stiffened shell tube of the experimental 14 mm gun tube facility which is used in part 1. Using single and double stacks is tried at two pressure levels of low-speed modes, which have response frequencies adapted with the used piezoelectric stacks characteristics. The maximum active damping ratio is occurred at high-pressure level. The radial circumferential strains are measured by using high-frequency strain gage system in phase with laser beam detection system similar to which used in part 1. Time resolved strain measurements of the wall response were obtained, and both precursor and transverse hoop strains have been resolved. A complete comparison had been made between the effect of active controlled and stepped structure cases, which indicate a significant attenuation ratio especially at higher operating pressures.

Download Full-text

Dynamic Stability of Cylindrical Shells under Moving Loads by Applying Advanced Controlling Techniques Part I—Using Periodic Stiffeners

Advances in Acoustics and Vibration ◽

10.1155/2009/317202 ◽

2009 ◽

Vol 2009 ◽

pp. 1-17

Author(s):

Khaled M. Saadeldin Eldalil ◽

Amr M. S. Baz

Keyword(s):

Critical Frequency ◽

Detection System ◽

Velocity Ratio ◽

Time Domain Analysis ◽

Transient Pressure ◽

Bending Vibrations ◽

Time Resolved ◽

Before And After ◽

Pointing Precision ◽

The Time Domain

The load acting on a cylindrical shell, with added periodic stiffeners, under a transient pressure pulse propelling a pullet (gun case) has been experimentally studied. This study is based on two modes of velocities, the first is subcritical mode and the second is supercritical mode. The stiffeners are added to the gun tube of an experimental gun facility, of 14 mm bore diameter. The radial strains are measured by using high-frequency strain gage system in phase with a laser beam detection system. Time-resolved strain measurement of the wall response is obtained and both precursor and transverse hoop strains have been resolved. The time domain analysis has been done using “wavelet transform package” in order to determine the frequency domain modes of vibrations and detect the critical frequency mode. A complete comparison of the dynamic behavior of the shell tube before and after adding periodic stiffeners has been done, which indicated that a significant damping effect reaches values between 61.5 and 38% for subcritical and critical modes. The critical frequency of the stiffened shell is increased, so the supercritical mode is changed to subcritical mode. The amplification and dispersion factors are determined and constructed; there is a reduction in the corresponding speed frequencies by about 10%. Also the radial-bending vibrations and tube muzzle motions are detected at muzzle velocity ratio of 0.99%, the results indicated that there is a significant improvement in increasing the number of rounds per second by about 36% and increasing the pointing precision by about 47%.

Download Full-text

Time resolved long-wave infrared laser-induced breakdown spectroscopy of inorganic energetic materials by a rapid mercury–cadmium–telluride linear array detection system

Applied Optics ◽

10.1364/ao.55.009166 ◽

2016 ◽

Vol 55 (32) ◽

pp. 9166 ◽

Cited By ~ 4

Author(s):

Clayton S.-C. Yang ◽

Feng Jin ◽

Sudhir Trivedi ◽

Eiei Brown ◽

Uwe Hommerich ◽

...

Keyword(s):

Energetic Materials ◽

Linear Array ◽

Detection System ◽

Laser Induced Breakdown Spectroscopy ◽

Time Resolved ◽

Breakdown Spectroscopy ◽

Long Wave ◽

Laser Induced Breakdown ◽

Array Detection ◽

Long Wave Infrared

Download Full-text

Dynamic Vibration Absorber for a Ropeway Carrier

Volume 1B: 16th Biennial Conference on Mechanical Vibration and Noise ◽

10.1115/detc97/vib-3944 ◽

1997 ◽

Author(s):

Hiroshi Matsuhisa ◽

Osamu Nishihara

Keyword(s):

Natural Frequency ◽

Damping Ratio ◽

Vibration Absorber ◽

Moving Mass ◽

Dynamic Vibration Absorber ◽

Damping Effect ◽

The World ◽

Dynamic Absorber ◽

First Time ◽

Suspended Bridge

Abstract Ropeways such as gondola lifts have attracted increasing interest as a means of transportation in cities. However, swing of ropeway carriers is easily caused by wind, and usually a ropeway cannot operate if the wind velocity exceeds about 15m/s. The study of how to reduce the wind-induced swing of ropeway carriers has attracted many researchers. It had been said that it was impossible to reduce the vibration of pendulum type structures such as ropeway carriers by a dynamic absorber. But in 1993, Matsuhisa showed that the swing of carrier can be reduced by a dynamic absorber if it is located far above or below from the center of oscillation. Based on this finding, a dynamic absorber composed of a moving mass on an arc-shaped track was designed for practical use, and it was installed in chairlift-type carriers and gondola type carriers in snow skiing sites in Japan in 1995 for the first time in the world. It has been shown that a dynamic absorber with the weight of one tenth of the carrier can reduce the swing to half. The liquid dynamic absorber was also investigated. It has the same damping effect as the conventional solid absorber. It is easy to adjust the natural frequency and the damping ratio, and the structure is simple. Therefore, it will be applied for not only ropeway carriers but also ships and rope suspended bridge and others.

Download Full-text

Multispectral LIF-Based Standoff Detection System for the Classification of CBE Hazards by Spectral and Temporal Features

Sensors ◽

10.3390/s20092524 ◽

2020 ◽

Vol 20 (9) ◽

pp. 2524 ◽

Cited By ~ 1

Author(s):

Lea Fellner ◽

Marian Kraus ◽

Florian Gebert ◽

Arne Walter ◽

Frank Duschek

Keyword(s):

Spectral Data ◽

Classification Accuracy ◽

Detection System ◽

Laser Source ◽

Nanosecond Laser ◽

Time Resolved Fluorescence ◽

Data Set ◽

Time Resolved ◽

Standoff Detection

Laser-induced fluorescence (LIF) is a well-established technique for monitoring chemical processes and for the standoff detection of biological substances because of its simple technical implementation and high sensitivity. Frequently, standoff LIF spectra from large molecules and bio-agents are only slightly structured and a gain of deeper information, such as classification, let alone identification, might become challenging. Improving the LIF technology by recording spectral and additionally time-resolved fluorescence emission, a significant gain of information can be achieved. This work presents results from a LIF based detection system and an analysis of the influence of time-resolved data on the classification accuracy. A multi-wavelength sub-nanosecond laser source is used to acquire spectral and time-resolved data from a standoff distance of 3.5 m. The data set contains data from seven different bacterial species and six types of oil. Classification is performed with a decision tree algorithm separately for spectral data, time-resolved data and the combination of both. The first findings show a valuable contribution of time-resolved fluorescence data to the classification of the investigated chemical and biological agents to their species level. Temporal and spectral data have been proven as partly complementary. The classification accuracy is increased from 86% for spectral data only to more than 92%.

Download Full-text

Sensitive, rapid procedure for time-resolved immunofluorometry of lutropin.

Clinical Chemistry ◽

10.1093/clinchem/34.8.1640 ◽

1988 ◽

Vol 34 (8) ◽

pp. 1640-1644 ◽

Cited By ~ 5

Author(s):

M J Khosravi ◽

R C Morton ◽

E P Diamandis

Keyword(s):

Monoclonal Antibody ◽

Solid Phase ◽

Detection System ◽

Time Resolved Fluorescence ◽

Time Resolved ◽

Practical Procedure ◽

Daily Monitoring ◽

Fluorescence Measurements ◽

Capture Antibody ◽

Europium Chelate

Abstract In this new immunofluorometric method for quantification of lutropin in serum, the "sandwich" principle is combined with time-resolved fluorescence measurements, with the europium chelate 4,7-bis(chlorosulfophenyl)-1,10-phenanthroline-2,9-dicarboxylic acid (BCPDA) used as label. A monoclonal antibody to the alpha-subunit of lutropin is adsorbed onto the walls of white-opaque microtiter wells to form the solid-phase capture antibody, and a biotin-labeled soluble monoclonal antibody is used for antigen quantification. The detection system is completed with streptavidin, which has been linked to a protein bulking agent labeled with multiple BCPDA residues. In the presence of excess europium, the fluorescence of the final complex attached to captured lutropin molecules is measured on the dried solid phasse with an automated time-resolved fluorometer. The assay can be performed as a rapid (less than 60 min incubation) or regular (150 min incubation) procedure. The rapid assay is well-suited for routine daily monitoring of increasing or ovulatory lutropin concentrations; the regular assay, with its greater sensitivity (0.5 int. unit/L), is a practical procedure for lutropin measurements in hyposecretory states. The assay measures up to 240 int. units/L, and results compare well with those by a commercially available radioimmunoassay, an immunoradiometric assay, and another time-resolved immunofluorometric procedure.

Download Full-text

Time-resolved orientation detection system with quantum cascade lasers

Review of Scientific Instruments ◽

10.1063/1.5028431 ◽

2018 ◽

Vol 89 (7) ◽

pp. 073101

Author(s):

Ke Ye ◽

Xiaowei Chen ◽

Wenwen Zhang ◽

Yankun Lv ◽

Lingpu Meng ◽

...

Keyword(s):

Quantum Cascade Lasers ◽

Detection System ◽

Time Resolved ◽

Quantum Cascade ◽

Orientation Detection ◽

Cascade Lasers

Download Full-text

A new instrument for time-resolved measurement of HO<sub>2</sub> radicals

Atmospheric Measurement Techniques ◽

10.5194/amt-13-839-2020 ◽

2020 ◽

Vol 13 (2) ◽

pp. 839-852 ◽

Cited By ~ 2

Author(s):

Thomas H. Speak ◽

Mark A. Blitz ◽

Daniel Stone ◽

Paul W. Seakins

Keyword(s):

Recent Literature ◽

Flash Photolysis ◽

Detection System ◽

Rate Coefficients ◽

Side Reactions ◽

Specific Rate ◽

Secondary Chemistry ◽

Time Resolved ◽

New Instrument ◽

Good Agreement

Abstract. OH and HO2 radicals are closely coupled in the atmospheric oxidation and combustion of volatile organic compounds (VOCs). Simultaneous measurement of HO2 yields and OH kinetics can provide the ability to assign site-specific rate coefficients that are important for understanding the oxidation mechanisms of VOCs. By coupling a fluorescence assay by gaseous expansion (FAGE) laser-induced fluorescence (LIF) detection system for OH and HO2 with a high-pressure laser flash photolysis system, it is possible to accurately measure OH pseudo-1st-order loss processes up to ∼100 000 s−1 and to determine HO2 yields via time-resolved measurements. This time resolution allows discrimination between primary HO2 from the target reaction and secondary production from side reactions. The apparatus was characterized by measuring yields from the reactions of OH with H2O2 (1:1 link between OH and HO2), with C2H4∕O2 (where secondary chemistry can generate HO2), with C2H6∕O2 (where there should be zero HO2 yield), and with CH3OH∕O2 (where there is a well-defined HO2 yield). As an application of the new instrument, the reaction of OH with n-butanol has been studied at 293 and 616 K. The bimolecular rate coefficient at 293 K, (9.24±0.21)×10-12 cm3 molec.−1 s−1, is in good agreement with recent literature, verifying that this instrument can measure accurate OH kinetics. At 616 K the regeneration of OH in the absence of O2, from the decomposition of the β-hydroxy radical, was observed, which allowed the determination of the fraction of OH reacting at the β site (0.23±0.04). Direct observation of the HO2 product in the presence of oxygen has allowed the assignment of the α-branching fractions (0.57±0.06) at 293 K and (0.54±0.04) at 616 K, again in good agreement with recent literature; branching ratios are key to modelling the ignition delay times of this potential “drop-in” biofuel.

Download Full-text

Time-resolved studies of low-temperature, EUV-induced plasmas: EUV emission in selected spectral ranges

Laser and Particle Beams ◽

10.1017/s0263034619000715 ◽

2019 ◽

Vol 37 (4) ◽

pp. 400-407 ◽

Cited By ~ 2

Author(s):

A. Bartnik ◽

H. Fiedorowicz ◽

P. Wachulak ◽

T. Fok

Keyword(s):

Low Temperature ◽

Excited States ◽

Extreme Ultraviolet ◽

Detection System ◽

Time Duration ◽

Time Resolved ◽

Euv Emission ◽

Decay Times ◽

Driving Pulse ◽

Spectral Ranges

AbstractInteraction of extreme ultraviolet (EUV) pulses of high intensity with gases results in the creation of non-thermalized plasmas. Energies of the driving photons and photoelectrons are sufficient for creation of excited states, followed by emission of the EUV photons. In most cases, decay times of these states are short comparing to the driving EUV pulse. It means that just after stopping of the driving pulse, the EUV emission corresponding to the excited states should also stop. From our earlier measurements in the optical range, however, it can be concluded that lifetimes of such plasmas exceed a time duration of the driving pulse even two orders of magnitude. Hence, it can be expected that the time duration of the EUV emission can be also significantly longer than the irradiation time. In this work, EUV-induced, low-temperature helium (He), krypton, and xenon plasmas were investigated. EUV emission from these plasmas was studied, using a specially prepared detection system, allowing for time-resolved measurements, in selected spectral ranges. The detection system was based on a paraboloidal collector and a semiconductor photodiode, sensitive for the EUV photons. For spectral selection, the corresponding filters or multilayer mirrors were employed. In most cases, the time duration of the EUV emission was significantly longer than the driving EUV pulse. In case of He plasmas, the emission corresponding to excited atoms was detected even hundreds of nanoseconds after the irradiation. It was also shown that the corresponding time profiles depended on densities of gases to be ionized.

Download Full-text

Passive Control of Vibration of Elastically Supported Beams Subjected to Moving Loads

Volume 1: 20th Biennial Conference on Mechanical Vibration and Noise, Parts A, B, and C ◽

10.1115/detc2005-84940 ◽

2005 ◽

Author(s):

D. Younesian ◽

E. Esmailzadeh ◽

M. H. Kargarnovin

Keyword(s):

High Speed ◽

Passive Control ◽

Vibration Suppression ◽

Damping Ratio ◽

Equations Of Motion ◽

Compressive Force ◽

Moving Loads ◽

Axial Compressive Force ◽

Before And After ◽

Elastically Supported

Vibration suppression of elastically supported beams subjected to moving loads is investigated in this work. For a Timoshenko beam with an arbitrary number of elastic supports, subjected to a constant axial compressive force, and having a tuned mass damper (TMD) installed at the mid-span, the equations of motion are derived and using the Galerkin approach the solution is sought. The optimum values of the frequency and damping ratio are determined both analytically and numerically and presented as some design curves directly applicable in the TMD design for bridge structures. To show the efficiency of the designed TMD, computer simulation for two real bridges, subjected to a S.K.S Japanese high-speed train, is carried out and the results obtained are compared for before and after the installation of the TMD system.

Download Full-text