The acoustic waves produced by the gas metal arc welding (GMAW) contain information about the behaviour of the arc column, the molten pool and droplet transfer. In this study measurements of acoustic ...waves generated during GMAW process were performed. Acoustic waves were measured in the surrounding air and in the parts being welded by employing a microphone and PZT sensor. To evaluate influences on sound generation extensive experiments were performed with two different unalloyed carbon steels: DIN RSt13 with 0.1% C and DIN Ck45 with 0.46% C, using two types of shielding gas: CO
2 and gas mixture by its brand name Crystal (90% Ar, 10% CO
2) and welding on a slope to vary the distance between welding nozzle and welding part. Acoustic signals were processed to obtain time domain and frequency domain descriptors. Some relationships between descriptors and the weld process characteristics were investigated. Results indicate that the arc sound exhibits distinct characteristics for each welding situation and that the main source of acoustic waves in short circuit metal transfer mode is arc reignition. From acoustic signals one can easily assess process stability and detect welding conditions resulting in weld defects.
The goal of this research is to use the information contained in the mechanisms occurring during the laser tattoo removal process. We simultaneously employed a laser-beam deflection probe (LBDP) to ...measure the shock wave and a camera to detect the plasma radiation, both originating from a high-intensity laser-pulse interaction with a tattoo. The experiments were performed
(skin phantoms),
(marking tattoos on pig skin), and
(professional and amateur decorative tattoos). The LBDP signal includes the information about the energy released during the interaction and indicates textural changes in the skin, which are specific for different skin and tattoo conditions. Using both sensors, we evaluated a measurement of threshold for skin damage and studied the effect of multiple pulses.
results show that a prepulse reduces the interaction strength and that a single strong pulse produces better removal results.
Q-switched laser tattoo removal Viljem H. topčič; Uroš G. Ahčan; Matjaž Lukač ...
Zdravniški vestnik (Ljubljana, Slovenia : 1992),
10/2013, Letnik:
82, Številka:
9
Journal Article
Recenzirano
Odprti dostop
Background: Decorative tattooing gained popularity in many western countries throughout the 1990s. Some estimates show that approximately 10 % of men in the United States already have tattoos. ...However, tattoos often become a personal regret. As recent surveys suggest, 17 % of people that have obtained a tattoo and more than 50 % of adults over the age of 40 in the United States of America consider having them removed. The same trend can be observed in our country as well. Laser therapy is the gold standard for tattoo removal. In Slovenia, laser tattoo removal therapy is available and widely accessible. There is a wide range of facilities offering laser tattoo removal, ranging from different private clinics to beauty salons. Different facilities use different lasers, but not all lasers, however, are optimal for successful and complete tattoo removal, as inappropriate use can cause many unwanted side effects.Methods: Eleven (11) patients (2 men and 9 women) requesting tattoo removal were treated in our department. When treating our patients, we used Fotona’s QX MAX quality-switched Nd:YAG laser which offers four different wavelengths in a single system; 1064 nm Nd:YAG was used to treat and remove dark pigments, 532 nm KTP for red, tan-colored, purple and orange tattoo inks, 650 nm dye for green tattoo inks and 585 nm dye for sky-blue colored inks.Results: Satisfactory tattoo removal was achieved in all patients treated. Patients were very satisfied with the success and the number of treatments needed for tattoo removal. There were mild unwanted side effects and the pain was moderate. The average number of treatments required for complete tattoo removal was less than 7, ranging from 3 to 21 treatments. Patients’ satisfaction with tattoo removal was estimated at 5.2 (on a scale from 1 to 6).Conclusions: Our study showed that Q-switched lasers successfully remove tattoo ink, however several treatments are required for satisfactory tattoo removal
Background: Decorative tattooing gained popularity in many western countries throughout the 1990s. Some estimates show that approximately 10 % of men in the United States already have tattoos. ...However, tattoos oen become a personal regret. As recent surveys suggest, 17 % of people that have obtained a tattoo and more than 50 % of adults over the age of 40 in the United States of America consider having them removed. The same trend can be observed in our country as well. Laser therapy is the gold standard for tattoo removal. In Slovenia, laser tattoo removal therapy is available and widely accessible. There is a wide range of facilities oering laser tattoo removal, ranging from dierent private clinics to beauty salons. Dierent facilities use dierent lasers, but not all lasers, however, are optimal for successful and complete tattoo removal, as inappropriate use can cause many unwanted side effects. Methods: Eleven (11) patients (2 men and 9 women) requesting tattoo removal were treated in our department. When treating our patients, we used Fotonas QX MAX quality-switched Nd:YAG laser which oers four dierent wavelengths in a single system; 1064 nm Nd:YAG was used to treat and remove dark pigments, 532 nm KTP for red, tan-colored, purple and orange tattoo inks, 650 nm dye for green tattoo inks and 585 nm dye for sky-blue colored inks. Results: Satisfactory tattoo removal was achieved in all patients treated. Patients were very satised with the success and the number of treatments needed for tattoo removal. There were mild unwanted side eects and the pain was moderate. The average number of treatments required for complete tattoo removal was less than 7, rang ing from 3 to 21 treatments. Patients satisfaction with tattoo removal was estimated at 5.2 (on a scale from 1 to 6). Conclusions: Our study showed that Q-switched lasers successfully remove tattoo ink, however several treatments are required for satisfactory tattoo removal.
In this paper, the influence of laser pulse shape on laser drilling process and on optoacoustic effect is studied. Results for two laser applications: laser drilling in aluminium and laser drilling ...in hard dental tissue are presented. Observed changes in the interaction processes are compared to the optoacoustic (OA) signals. Results confirm that laser pulse shape might have a significant influence on the interaction processes and can be used to increase machining efficiencies. With laser pulse shape, one can effectively induce desired dynamics of the melted material. However, if the process is cumulative in its nature like in the case of drilling in dentin, then the laser pulse shape is less important. Optoacoustic signals are found to depend on the laser pulse shape. However, usually used signal parameters for on line monitoring are not linearly correlated with the drilling efficiency. At least more complex signal analysis is needed. Presented method of signal analysis enables determination of the onset time of changes in the interaction mechanism and determination of energy threshold in the case of hard dental tissue drilling.
Measurements of laser drilling rate of different woods were performed. Using an Er:YAG laser, very long and narrow holes with depth-to-diameter ratio above 100 were achieved. This indicates the ...occurrence of laser beam trapping. The process has been investigated as a typical optodynamic process. Optoacoustic waves were detected by microphone and analysed to monitor the hole depth produced by consecutive laser pulse exposure of the same spot. The results may have relevance to Er:YAG laser applications in the wood industry.
Er:YAG laser drilling of dental tissue has been investigated as the typical optodynamic process. Optoacoustic signals were detected by microphone and analyzed within the frame of linear systems ...theory to monitor laser induced microexplosions. Statistical distribution of the optodynamic efficiency was performed in terms of partial weights of optoacoustic response function. The results indicate that the laser spikes shorter than 2 μs are more efficient in ablative mechanism.
Ko je naša 3. četa III. bataljona II. grupe narasla skoraj na število dveh čet, jo je Zdravko (Zvonko Trpin) preimenoval v polbataljon. Komandir prve skupine je ostal Zdravko, drugo, v kateri sem bil ...tudi jaz, pa je izročil Šiški. Nato smo se za dva dni ločili, na večer 18. maja se zopet sešli in odšli na Polico, kjer nas je čakala vsa grupa. Na mesto smo prišli šele zjutraj, toda dolgo nismo mogli počivati, ker se je še isto dopoldne grupa reorganizirala in je nastalo 5 bataljonov. Iz našega polbataljona sta nastala z izpolnitvijo dva samostojna bataljona, tako da je bil komandant enega Zdravko, drugega pa Šiška. Jaz sem ostal pri Šiški, komandir čete je postal Brane, vodnik pa partizan »Tank«. Po tej reorganizaciji smo šli počivat, ker nas je čakal zvečer naporen marš. Bil je napovedan odhod na Štajersko. Razdelili so nam še suho hrano, konserve, municijo, nato je bil pregled obleke in orožja in tako je med pripravami nastopil večer. ...
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