The aim of the study reported here is the development of a new method which allows rapid and accurate in-vitro measurements of three-dimensional (3D) shape of laser ablated craters in hard dental ...tissues and the determination of crater volume, ablation rate and speed. The method is based on the optical triangulation principle. A laser sheet projector illuminates the surface of a tooth, mounted on a linear translation stage. As the tooth is moved by the translation stage a fast digital video camera captures series of images of the illuminated surface. The images are analyzed to determine a 3D model of the surface. Custom software is employed to analyze the 3D model and to determine the volume of the ablated craters. Key characteristics of the method are discussed as well as some practical aspects pertinent to its use. The method has been employed in an in-vitro study to examine the ablation rates and speeds of the two main laser types currently employed in dentistry, Er:YAG and Er,Cr:YSGG. Ten samples of extracted human molar teeth were irradiated with laser pulse energies from 80 mJ to the maximum available energy (970
mJ with the Er:YAG, and 260
mJ with the Er,Cr:YSGG). About 2000 images of each ablated tooth surface have been acquired along a translation range of 10
mm, taking about 10
s and providing close to 1 million surface measurement points. Volumes of 170 ablated craters (half of them in dentine and the other half in enamel) were determined from this data and used to examine the ablated volume per pulse energy and ablation speed. The results show that, under the same conditions, the ablated volume per pulse energy achieved by the Er:YAG laser exceeds that of the Er,Cr:YSGG laser in almost all regimes for dentine and enamel. The maximum Er:YAG laser ablation speeds (1.2
mm
3/s in dentine and 0.7
mm
3/s in enamel) exceed those obtained by the Er,Cr:YSGG laser (0.39
mm
3/s in dentine and 0.12
mm
3/s in enamel). Since the presented method proves to be easy to use and allows quite rapid measurements it may become a valuable tool to study the influence of various laser parameters on the outcome of laser ablation of dental tissues.
A new method for rapid and accurate acquisition of the shape of an electrode indentation in a workpiece during resistance spot welding (RSW) is presented. The method is based on illumination of the ...indentation with structured laser light and detection of the image of the illuminated object using a charge coupled device camera. The image from the camera is digitised using a frame grabber and fed into a personal computer where it is processed and analysed. This paper presents the basic principles of the method and discusses the image processing algorithms developed to measure the indentation shape characteristics, such as diameter, depth, and volume. Results from an application of the method to study electrode wear during RSW of zinc coated steel are also presented.
A new method for non-stationary temperature field measurement in air is presented. Optoacoustic generation is used to emit short acoustic transients within the observed field. The transient deflects ...a probe laser beam which is folded by 2 parallel mirrors in such a way that it passes through the observed field several times before it reaches a position sensitive photodetector. The timing of the acoustic wavefront transits at several distances from the source is obtained from a single oscilloscope trace of the photodetector output. By measuring the acoustic wavefront transit times and the distances between the probe beam segments, the velocity of sound is determined and from this the local temperature can be calculated. (Original abstract)
The contribution presents a laser-based method for three-dimensional (3D) measurements of the shape of electrode indentation. The method is based on illumination of the indentation with structured ...light and detection of the image of the illuminated indentation by means of a digital camera. Image processing algorithms are employed to determine the 3D shape of the indentation. A batch of welds obtained form an automotive production process has been measured and analyzed for characteristic geometrical indentation parameters such as diameter, depth, presence of cracks and splash etc. The potential of indentation shape parameters to serve as indicators of spot quality is discussed.
Measurements of the weld surface based on laser profilometry are presented. New possibilities for collecting information about the welding process and the condition of the weld are described. ...Real-time measurement of the weld shape, data processing and optimal adjustment of welding parameters (voltage, current, pressure, electrode and welded surface conditions ...) can improve quality and reliability of welds and reduce the use of material and energy resulting from large eject.
Abstract Background Within cardio-oncology, emerging epidemiologic studies have demonstrated a bi-directional relationship between heart failure (HF) and cancer. In the current study, we aimed to ...further explore this relationship and investigate the underlying pathophysiological pathways that connect these two disease entities. Methods We conducted a post-hoc analysis in which we identified 24 Gene Ontology (GO) processes associated with the hallmarks of cancer based on 92 biomarkers in 1960 patients with HF. We performed Spearman’s correlations and Cox-regression analyses to evaluate associations with HF biomarkers, severity and all-cause mortality. Results Out of a total of 24 GO processes, 9 biological processes were significantly associated with adverse clinical outcome. Positive regulation of mononuclear cell proliferation demonstrated the highest hazard for reaching the clinical endpoint, even after adjusting for confounders: all-cause mortality HR 2.00 (95% CI 1.17–3.42), p = 0.012. In contrast, negative regulation of apoptotic process was consistently associated with a lower hazard of reaching the clinical outcome, even after adjusting for confounders: all-cause mortality HR 0.74 (95% CI 0.59–0.95), p = 0.016. All processes significantly correlated with HF biomarkers, renal function and HF severity. Conclusions In patients with HF, GO processes associated with hallmarks of cancer are associated with HF biomarkers, severity and all-cause mortality.
Biogas plants that process raw materials from agriculture, such as poultry manure, are one of the most significant applications of anaerobic fermentation. In Asian countries, particularly in China, ...India, Nepal and Vietnam, there are several million very simple, small biogas plants that produce gas for household cooking and lighting. In Europe and North America a number of agricultural biogas plants now, are increasing daily, a few thousand biogas plants exist, most of which use modern technologies, anaerobic fermentation. The aim of this paper is to determine the possibility of biogas production from poultry manure with 10% of total solids and through the segments of the quality and quantity, determine the content of total solids (DM), volatile solids (OM), and the amount and composition of biogas. The aim was also to justify the use of poultry manure in biogas production and its application for specific purposes Laboratory research showed that 1 kg of poultry 10% of poultry manure produced 47.01 l of biogas during the 40 days of anaerobic fermentation under mezofilic conditions. Production of biogas has a good potential for development in Croatia, especially in the continental part. Usages of this technology are multiple because of the fact that the Republic of Croatia imports most of the energy. Usage of biogas would reduce the import of certain energy and thus reduce energy dependence; it would increase the number of employers and ease the obligation of Croatia toward EU in replacing some fossil fuels with renewable ones.
INTRODUCTION: Ophthalmic examination in the horse is generally limited to crude assessment of vision and screening for ocular lesions. The refractive state of equine eyes and the potential impact on ...vision and performance requires further investigation. OBJECTIVE: To assess the refractive state of a large, mixed‐breed sample of horses and ponies in the United Kingdom (UK). PROCEDURE: The refractive state of both eyes of 333 horses and ponies was determined by streak retinoscopy, and the effect of age, height, gender, breed and management regime on the refractive state assessed. RESULTS: Emmetropia was found in 557 of 666 (83.63%) of eyes; 228/333 (68.5%) of the horses/ponies were emmetropic in both eyes. Refractive errors of greater than 1.50 D (in either direction) were found in 2.7% of the eyes tested. Ametropic eyes included hyperopia (54%) and myopia (46%). Anisometropia was found in 30.3% of horses and ponies. Breed of horse/pony was the only factor that affected refractive state (in the left eye only, P < 0.05) with Thoroughbred crosses having a tendency toward myopia and Warmbloods/Shires toward hyperopia. DISCUSSION AND CONCLUSION: The retinoscopic survey found emmetropia to be the predominant refractive state of the equine eye with no evidence of an overall trend toward myopia or hyperopia. However, individual and breed‐related differences were found. Such factors should be considered in the selection of horses for sport and leisure, and when evaluating their performance potential. More comprehensive visual testing would be valuable in identifying underlying causes of behavioral problems.
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