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Tailoring the Pressure Profile of TEA-CO2 Laser-Induced Shock Waves for Mechanical Forming and Separation Processes
摘要： For laser shock processes, the acting pressure can be increased by confining the propagation of the laser-induced plasma. Water or glass is commonly used as confinement for laser shock waves induced by Nd:YAG-lasers. This is not possible for the longer wavelength of TEA-CO2 lasers due to higher absorption coefficients. Instead, the acting pressure can be manipulated with a pressure cell above the workpiece. Two different pressure cells were designed to test the versatility of this concept. A cylindrical pressure cell design was used to confine the propagation of the laser-induced plasma and a parabolic pressure cell design was used to reflect the shock wave back to the workpiece. The effect of the pressure cells was analysed by time-resolved force measurements and evaluated for maximum force and force duration. This study shows that the cylindrical pressure cell strongly increases the maximum force while the parabolic pressure cell maximises the duration of force application. Furthermore, the pressure cells have been applied to the laser shock-based processes laser shock punching and LiSE hardness measurement. The cylindrical pressure cell strongly enhances the results of both processes, while the parabolic pressure cell shows only a minor effect.
关键词： Micro punching,TEA CO2 laser,Indentation hardness,Laser supported detonation wave,Micro manufacturing
更新于2025-09-16 10:30:52
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Comparative studies of photo-acoustic gas analyzers based on tunable CO2 lasers with external and intracavity detector arrangement
摘要： The results of comparative studies of laser photo-acoustic (PA) gas analyzers with external and intracavity arrangement of resonant differential photo-acoustic detector (PAD) are presented. An automated tunable waveguide RF-excited CO2 laser was used in the PA gas analyzers. During the experiments, the optimal design of the resonant differential PAD was determined, in which the various models of microphones were tested. Studies of the effect of gas flow rate through the PAD, measurements of gas absorption spectrum (CO2) at different PAD resonant frequencies have been carried out. Two versions of transportable PA gas analyzers with different detector arrangements are developed and tested: outside and inside the cavity of tunable CO2 laser. For an integration time of 1 s, the minimum detectable absorption for the external PA gas analyzer is αmin = 7.5×10-10 cm-1, for the intracavity PA gas analyzer αmin ~ (3.5 ± 0.4)×10-10 cm-1. It is shown that the value of the minimum detectable absorption αmin is practically independent of the external or intracavity location of the differential PAD, i.e. from the power of CO2 laser radiation in the range of ~1.5-100 W.
关键词： resonant differential photo-acoustic detector,laser photo-acoustic gas analyzer,tunable waveguide RF-excited CO2 laser
更新于2025-09-16 10:30:52
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Gutartige Lidtumoren: CO2-Laser statt Skalpell
摘要： Gutartige Tumoren am Augenlid werden zumeist chirurgisch entfernt. Dies erfolgt so wenig invasisv und so kosmetisch wie m?glich; dennoch gibt es Patienten, denen man z. B. aufgrund ihrer allgemeinen Verfassung oder ihrer Vorbehalte eine Alternative anbieten m?chte. Dies kann z. B. eine Laserbehandlung sein: Eine retrospektive klinische Studie analysierte die Ergebnisse einer Tumorexzision mit dem ultragepulsten CO2-Laser.
关键词： surgical alternative,laser therapy,benign eyelid tumors,CO2-Laser
更新于2025-09-16 10:30:52
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Comparison and Identification of Suitable Multi-Response Optimization Technique for Laser Welding Process Parameters
摘要： In the present research work, comparison of four different multi-response optimization techniques viz., multi-response signal-to-noise ratio (MRSN), weighted signal-to-noise ratio (WSN), grey relational grade analysis (GRA) and the technique for order preference by similarity to ideal solution method (TOPSIS) have been applied in a case study of laser welding process for joining automotive gears of 16MnCr5 Alloy Steel. It has been observed that (MRSN) method gives the closest results and can be considered as the best suitable method for this case. The authors conclude that this approach could be applicable for any manufacturing application.
关键词： Power cost,Fraction Defective,Weld Depth,CO2 Laser,Taguchi quality Loss,Welding Speed,Laser Power,Alloy Steel 16Mn Cr5
更新于2025-09-16 10:30:52
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Laryngeal Cancer (Clinical Case-Based Approaches) || 4 T1b Glottic Cancer Treated with Transoral Laser Surgery
摘要： T1b squamous cell carcinoma (SCC) of the glot- tis can be treated with radiotherapy or transoral laser surgery. Radiotherapy is usually advocated since voice results are considered better compared to transoral laser surgery; nevertheless, the tran- soral approach is also frequently performed for T1b at the request of the patients. In such cases, special care is needed to avoid unexpected scar. This chapter reports the typical case of a T1b SCC of the glottis with involvement of the anterior commissure observed in a 69-year-old male with a clinical history of daily cigarette smoking for 20 years, and progressive hoarseness lasting for 1 year, who underwent en bloc bilateral subligamen- tal type II cordectomy. The patient, after 3 years of follow-up, is free of cancer. The endoscopic treat- ment in the form of type II cordectomy was chosen for the following reasons: (1) the surgical strat- egy has the advantages of a histologically proven resection without residual cancer and, in case of recurrence a further surgical treatment (includ- ing transoral surgery) and also radiotherapy are still available; (2) early cancer of the glottis is associated with a low incidence of occult metas- tasis and there is no indication for the neck dis- section in cN0 patients; (3) the transoral approach allows for treatment of the cancer with minimal complications, low trauma to healthy tissue, and without the need for tracheostomy and/or nasoga- stic feeding tube; (4) the patient requested to be treated quickly in one stage. In our opinion, tran- soral CO2 laser microsurgery is an important treat- ment option in T1b cancer of glottis.
关键词： laryngeal microsurgery,T1b glottic carcinoma,CO2 laser
更新于2025-09-16 10:30:52
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Laser surface modification of structural glass for anti-slip applications
摘要： The use of soda-lime silicate glass as a structural element has become frequent in modern buildings. The load-bearing applications of glass in floors, footbridges, terraces, or stairs require an optimal combination of non-slippery properties of the surface, element weight, and strength, and structural glazing can be compromised by the incorporation of laser surface patterned ornamental motifs. Laser surface modification has significant advantages for selective surface area modification; nevertheless, the mechanical performance of the processed glass remains unknown, which precludes reliable structural calculations and employment in construction. In this study, we investigated the surface modification of annealed and heat-strengthened glass via CO2 laser scanning for the production of rough anti-slip surfaces. The surface roughness and the reduction of the bearing load strength were quantified. Slip resistance-enhanced surfaces with roughness values (Rz) above 20 μm and characteristic bending strength preservation up to 74% were obtained. The results pave the way for the use of laser surface-modified plates in laminated glass elements with optimized strength calculation and weight reduction.
关键词： CO2 laser,Heat strengthened glass,Surface treatment,Structural glass
更新于2025-09-16 10:30:52
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Neural networks based prediction modelling of hybrid laser beam welding process parameters with sensitivity analysis
摘要： Present paper attempted to model complex relationship between CO2 laser–MIG hybrid welding parameters and it has been completed using different algorithms of artificial neural networks (ANN). Input parameters for the study include laser power, welding speeds and wires feed rate and tensile strength of the joint is considered as output. A full factorial experimental dataset is used for the purpose. Variants of back propagation neural networks (BPNN) and Radial Basis Function Networks have been used as training algorithm. Altogether 65 different ANN architecture have been trained and tested using 6 different training algorithms to find out ANN with best prediction capability. 3-11-1 ANN architecture trained using BPNN with Bayesian regularization shows best prediction capability (mean square error 3.24E ? 04) and considered as Best ANN. That ANN will be useful for determining required value of welding process parameters to yield a specific welding strength and suitable for online process monitoring and control. Finally, a sensitivity analysis has been conducted and it is found that, maximum welding strength can be obtained with low wire feed rate (4 m/min), low welding speed (2 m/min) and high laser power (3 kW).
关键词： Sensitivity analysis,Hybrid CO2 laser-MIG welding,Artificial neural networks
更新于2025-09-16 10:30:52
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Optimization of CO 2 Laser Cutting of Stainless Steel Sheet for Curved Profile
摘要： Laser cutting is one of the most widely used thermal energy based non-contact type advance machining process. In recent years, considerable experimental investigations have been carried out aiming at improving laser cutting process performance. In this work CO2 laser cutting parameters on stainless steel 304 width 2.5 mm thickness were studied. The cut quality achieved minimum kerf width to cut stainless steel sheet depends on appropriate selection process parameters was investigated. The parameters consider to include laser output power, cutting speed, gas pressure. The effect of cutting parameter on the cut quality was further investigated by monitoring top kerf width, and bottom kerf width using box –behnken designing the response surface methodology. And finally optimized best CO2 laser cutting parameters are selected by using genetic algorithm approach.
关键词： Kerf width,Stainless steel 304,CO2 Laser cutting,GA,RSM
更新于2025-09-16 10:30:52
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Energy dependence of Cl emission lines in CO <sub/>2</sub> laser induced breakdown spectroscopy
摘要： Chlorine (Cl) detection using laser induced breakdown spectroscopy (LIBS) techniques in geology and environment samples is still challenging since the experimental conditions greatly influence the analytical performance of LIBS. Cl emission in LIBS must be studied carefully to find the optimum condition to allow Cl detection. In the present study, Cl emission was studied from polyvinyl chloride (PVC) sample containing Cl as major element. A Transversely Excited Atmosphere (TEA) carbon dioxide (CO2) laser was used for inducing plasma from the sample. Cl emission was investigated by varying the experimental conditions, especially energy of the laser pulse. The emission spectrum from the consequent plasma was detected using an Optical Multichannel Analyzer (OMA) system. It was found that Cl emission lines only can be obtained when helium was used as the surrounding gas. The strongest emission line of Cl I 837.59 nm in the infrared region cannot be detected even under helium surrounding gas. Instead, many ionic emission lines of Cl in ultraviolet regions including the strong ionic lines (Cl II 479.45 nm, Cl II 481.00 nm, Cl II 481.94 nm and the weak lines (Cl II 476. 86 nm, Cl II 478.13 nm, Cl II 489.67 nm, Cl II 490.47 nm and Cl II 491.77 nm) can unequivocally be detected. It was also found that the intensity of Cl emission lines critically depends on the energy of the laser pulse, namely the emission intensity of Cl lines increases sharply with energy. In present work, the highest intensity of Cl emission lines was obtained when the energy of the laser pulse was about 2500 mJ, giving strong and clear Cl emission lines with low background and relatively high signal to background ratio of more than 3.
关键词： LIBS,PVC,helium surrounding gas,TEA CO2 laser,Chlorine detection
更新于2025-09-16 10:30:52
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Anatomy of the Brachycephalic Canine Hard Palate and Treatment of Acquired Palatitis Using CO <sub/>2</sub> Laser
摘要： The goal of this article is to review the anatomy of the brachycephalic canine hard palate and provide a step-by-step guide on diagnosis and treatment of acquired palatitis using the CO2 surgical laser. Brachycephalic breed-related defects are not only limited to the upper airways, some dogs may develop secondary systemic or localized problems. An abnormality that is over-represented in some breeds such as boxers and bulldogs is prominent palatal rugae. The greater depth of the palatal rugae allows for the entrapment of plaque, food debris and hair. Thus, acquired palatitis or granulomatous lesions may develop. This oral pathology and its consequences are commonly neglected by the owners and frequently missed by the veterinarians. Scientific evidence-based diagnosis and treatment for this breed-related oral pathology are absent in the veterinary literature. This article is the first in providing the elements needed for an adequate morphological characterization of the canine hard palate, allowing veterinarians to appropriately identify anomalous areas of the soft tissue component of the hard palate. This article illustrates the use of a noninvasive surgical technique to prevent and cure the sequelae associated with anomalous palatal rugae. The CO2 surgical laser provides a suitable method by offering the fast resolution of the lesions and permanent results.
关键词： palatine folds,brachycephalic dog,palatal rugae,acquired palatitis,CO2 laser,canine hard palate
更新于2025-09-16 10:30:52