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Vibration Measurements (vibration + measurement)
Selected AbstractsPowered Liposuction: An Evaluation of Currently Available InstrumentationDERMATOLOGIC SURGERY, Issue 5 2002Timothy Corcoran Flynn MD background. Over the past several years, powered liposuction instruments have become available to the dermatologic surgeon. These instruments all move the cannula forward and backward 2,12 mm with rapidity. This motion simulates the standard human movement of the cannula and facilitates movement through the tissue. Powered liposuction may help to prevent surgeon fatigue and has recently been shown to aid in the efficacy of fat removal. objective. To compare and contrast currently available powered liposuction instruments, to obtain objective engineering data on the instruments, and to compare the instruments when used on actual liposuction cases. methods. Five currently available powered liposuction systems were evaluated by the author. Each instrument was used with a 3 mm dual side port cannula on patients undergoing tumescent liposuction. An independent engineering firm, who collected objective measurements such as weight, stroke force, temperature, and vibration measurements on the instruments, evaluated the units. Noise measurements were obtained. results. Each of the five systems showed advantages and disadvantages. Important issues were the size and weight of the units, as well as whether they were driven electrically or pneumatically. Stroke force is variable (range 9.5,30 pounds). The noise of the units ranged between 60 and 87 dB. Vibration measurements varied from instrument to instrument. Units produced a variable amount of heat ranging from 77°F to 102°F. Most instruments are autoclavable, and one system is disposable. Build quality and reliability varied with the instrument. conclusion. Instruments for powered liposuction have emerged in the last 2 years, with each instrument having distinct advantages and disadvantages. This article reviews five currently available powered liposuction instruments and presents objective measurements as well as the author's experience using the instruments. [source] Empirical estimate of fundamental frequencies and damping for Italian buildingsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 8 2009Maria Rosaria Gallipoli Abstract The aim of this work is to estimate the fundamental translational frequencies and relative damping of a large number of existing buildings, performing ambient vibration measurements. The first part of the work is devoted to the comparison of the results obtained with microtremor measurements with those obtained from earthquake recordings using four different techniques: horizontal-to-vertical spectral ratio, standard spectral ratio, non-parametric damping analysis (NonPaDAn) and half bandwidth method. We recorded local earthquakes on a five floors reinforced concrete building with a pair of accelerometers located on the ground and on top floor, and then collected microtremors at the same location of the accelerometers. The agreement between the results obtained with microtremors and earthquakes has encouraged extending ambient noise measurements to a large number of buildings. We analysed the data with the above-mentioned methods to obtain the two main translational frequencies in orthogonal directions and their relative damping for 80 buildings in the urban areas of Potenza and Senigallia (Italy). The frequencies determined with different techniques are in good agreement. We do not have the same satisfactory results for the estimates of damping: the NonPaDAn provides estimates that are less dispersed and grouped around values that appear to be more realistic. Finally, we have compared the measured frequencies with other experimental results and theoretical models. Our results confirm, as reported by previous authors, that the theoretical period,height relationships overestimate the experimental data. Copyright © 2008 John Wiley & Sons, Ltd. [source] Dynamic performance of the beam position monitor support at the SSRFJOURNAL OF SYNCHROTRON RADIATION, Issue 1 2009Xiao Wang Electron beam stability is very important for third-generation light sources, especially for the Shanghai Synchrotron Radiation Facility whose ground vibrations are much larger than those for other light sources. Beam position monitors (BPMs), used to monitor the position of the electron beam, require a greater stability than other mechanical structures. This paper concentrates on an investigation of the dynamic performance of the BPM support prototype. Modal and response analyses have been carried out by finite-element (FE) calculations and vibration measurements. Inconsistent results between calculation and measurement have motivated a change in the soft connections between the support and the ground from a ground bolt in the initial design to full grout. As a result the mechanical stability of the BPM support is greatly improved, showing an increase in the first eigenfrequency from 20.2,Hz to 50.2,Hz and a decrease in the ratio of the root-mean-square displacement (4,50,Hz) between the ground and the top of the support from 4.36 to 1.23 in the lateral direction. An example is given to show how FE analysis can guide the mechanical design and dynamic measurements (i.e. it is not just used as a verification method). Similar ideas can be applied to improve the stability of other mechanical structures. [source] Damage Detection by Wave Propagation Observation with Laser SpeckleInterferometryPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2005Alexander Schmidt For quality insurance and fault detection, one and three dimensional ESPI (Electronic Speckle Pattern Interferometry) technique is applied to various structures. These experiments are an extension of previous experiments with Holographic Interferometry [4], a related measurement technique. ESPI is a non contact, high resolution Laser measurement technique. It facilitates transient full field vibration measurements that deliver absolute deflections, either one dimensional out-of-plane or three dimensional in and out-of-plane. Experiments have been performed with a full scale concrete embedded track segment. Different known artificial defects represent various flaws and voids due to the fabrication process and operation. Wave propagation due to impact is observed and allows for damage detection. ESPI measurements are in good accordance with expectations. An in-situ measurement setup for quality management of concrete embedded railway tracks has been built. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Flankenübertragung bei Massivholzkonstruktionen , Teil 2: Einfluss von Befestigungsmitteln auf die Verbesserung durch den Einbau elastischer ZwischenschichtenBAUPHYSIK, Issue 5 2008Franz Dolezal DI Dieses Thema wird in zwei Aufsätzen zur Flankenübertragung abgehandelt. In Teil 1 wurde die Verbesserung der Flankendämmung durch den Einbau elastischer Zwischenschichten untersucht und die Anwendbarkeit der EN 12354 verifiziert. Während elastische Zwischenschichten, wie in Teil 1 erläutert, zu einer wesentlichen Erhöhung der Flankendämmung führen, wird diese jedoch durch die Anordnung von statisch erforderlichen Befestigungsmitteln massiv beeinträchtigt. Mittels Schall- und Schwingungsmessungen wird deren Einfluss quantifiziert und der jeweiligen Befestigungsmaßnahme zugeordnet. Schalltechnisch optimierte Befestigungsmittel werden präsentiert und deren akusti-sches Verbesserungspotential ausgelotet. Flanking-Transmission at Solid Wood Constructions. Part 2: Influence of Fasteners on the Improvement by Application of Flexible Interlayers. As shown in part 1, the application of elastic interlayers leads to significant improvement of flanking insulation. Their impact is, however, highly affected by installation of required metal fasteners. By means of sound and vibration measurements their influence is quantified and assigned to the particular connection. Optimized fasteners are presented and their acoustical potential is verified. [source] Rückbau einer 400 m langen Autobahnbrücke unter besonderen Rahmenbedingungen , BAB A 6, Neckarbrücke MannheimBAUTECHNIK, Issue 5 2005Martin Osieja Dipl.-Ing. Es wird über den Rückbau der alten Neckarbrücke Mannheim im Zuge der BAB A 6 berichtet. Bei diesem Bauwerk bestand jeder der beiden Überbauten aus sechs Bögen mit einer Gesamtlänge von rund 400 m. Je fünf der sechs Bögen wurden durch Sprengen zum Einsturz gebracht. Die beiden Bögen über der Schiffahrtsstraße Neckar durften nicht gesprengt werden und mußten aus diesem Grunde in einzelnen Schritten abgetragen werden. Beim Rückbau waren bestimmte Bedingungen gebührend zu berücksichtigen. Vor allem durften zwei das Bauwerk querende Gashochdruckleitungen in keiner Weise beschädigt werden. Zu ihrem Schutz wurden sie mit beachtlichen Fallbetten überbaut. Der Weg, der zu diesen Fallbetten führte, wird aufgezeigt. Zudem werden die bei den Sprengungen durchgeführten Erschütterungsmessungen sowie deren Ergebnisse vorgestellt. Die mit diesem Rückbau gewonnenen Erfahrungen werden wiedergegeben. Demolition of a 400-metre long expressway bridge under particular circumstances , BAB A 6, Neckar bridge Mannheim. This text is about the demolition of the former Neckar bridge Mannheim, situated along the German federal expressway A 6. This construction was composed of two superstructures, which respectively consisted of six arches. Five of the six arches of each superstructure were blasted. The two remaining arches above the Neckar channel could not be blown up due to vessel traffic, and for this reason had to be gradually dismantled. There were a number of aspects that had to be carefully considered during the demolition, especially the presence of two high-pressure gas pipes that run across the construction site. To prevent damage to the pipes, abundant mounds of sand were placed on top of them. The way that led to these mounds is illustrated in this article. Furthermore, the vibration measurements as well as their results are also presented. The experiences gained from this demolition are illustrated in this article. [source] | ||||||||||