Готові списки джерел за темами / Single Scan Track

Добірка наукової літератури з теми "Single Scan Track"

Автор: Grafiati

Опубліковано: 14 березня 2023

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Статті в журналах з теми "Single Scan Track"

Aversa, Alberta, Mandanà Moshiri, Erica Librera, Mehdi Hadi, Giulio Marchese, Diego Manfredi, Massimo Lorusso, et al. "Single scan track analyses on aluminium based powders." Journal of Materials Processing Technology 255 (May 2018): 17–25. http://dx.doi.org/10.1016/j.jmatprotec.2017.11.055.

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Musicki, Darko, Barbara La Scala, and Robin Evans. "Integrated track splitting filter-efficient multi-scan single target tracking in clutter." IEEE Transactions on Aerospace and Electronic Systems 43, no. 99 (2007): 1409–25. http://dx.doi.org/10.1109/taes.2007.4407467.

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Musicki, D., B. F. La Scala, and R. J. Evans. "Integrated track splitting filter - efficient multi-scan single target tracking in clutter." IEEE Transactions on Aerospace and Electronic Systems 43, no. 4 (October 2007): 1409–25. http://dx.doi.org/10.1109/taes.2007.4441748.

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Ning, Jinqiang, Daniel Sievers, Hamid Garmestani, and Steven Liang. "Analytical Modeling of In-Process Temperature in Powder Bed Additive Manufacturing Considering Laser Power Absorption, Latent Heat, Scanning Strategy, and Powder Packing." Materials 12, no. 5 (March 8, 2019): 808. http://dx.doi.org/10.3390/ma12050808.

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Temperature distribution gradient in metal powder bed additive manufacturing (MPBAM) directly controls the mechanical properties and dimensional accuracy of the build part. Experimental approach and numerical modeling approach for temperature in MPBAM are limited by the restricted accessibility and high computational cost, respectively. Analytical models were reported with high computational efficiency, but the developed models employed a moving coordinate and semi-infinite medium assumption, which neglected the part dimensions, and thus reduced their usefulness in real applications. This paper investigates the in-process temperature in MPBAM through analytical modeling using a stationary coordinate with an origin at the part boundary (absolute coordinate). Analytical solutions are developed for temperature prediction of single-track scan and multi-track scans considering scanning strategy. Inconel 625 is chosen to test the proposed model. Laser power absorption is inversely identified with the prediction of molten pool dimensions. Latent heat is considered using the heat integration method. The molten pool evolution is investigated with respect to scanning time. The stabilized temperatures in the single-track scan and bidirectional scans are predicted under various process conditions. Close agreements are observed upon validation to the experimental values in the literature. Furthermore, a positive relationship between molten pool dimensions and powder packing porosity was observed through sensitivity analysis. With benefits of the absolute coordinate, and high computational efficiency, the presented model can predict the temperature for a dimensional part during MPBAM, which can be used to further investigate residual stress and distortion in real applications.

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Wang, Li, Qing Song Wei, Yu Sheng Shi, Jin Hui Liu, and Wen Ting He. "Experimental Investigation into the Single-Track of Selective Laser Melting of IN625." Advanced Materials Research 233-235 (May 2011): 2844–48. http://dx.doi.org/10.4028/www.scientific.net/amr.233-235.2844.

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Selective laser melting(SLM) is driven by the need to fabricate functional metallic parts and tools with near shape and density. The method of process to fabricate a metal part will save materials, time and energy compared to the traditional manufacturing methods. Unlike the selective laser sintering (SLS), the metal powder particles are molten by the laser beam during the process of selective laser melting. In this paper, IN625 powders were adopted to investigate the characters of single molten track. The factors that affect the surface quality and relative density are the process parameters such as the laser energy, scan speed and so on. They were studied to find out the correlation between the parameters and formation of single-track. It has been found that Optimal ratio between laser power and scanning speed (P/v) is 1-1.5 for IN625 SLM. P/v is the linear energy density. It also has been found that the width and height of single-track can be calculated when the linear energy density is given. In this study the laser power, scan spacing and the hatch spacing which affect the surface quality and the relative density of the metallic parts were optimized.

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Childs, T. H. C., C. Hauser, and M. Badrossamay. "Mapping and Modelling Single Scan Track Formation in Direct Metal Selective Laser Melting." CIRP Annals 53, no. 1 (2004): 191–94. http://dx.doi.org/10.1016/s0007-8506(07)60676-3.

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Park, Suyeul, Seok Kim, and Heechang Seo. "Study on Representative Parameters of Reverse Engineering for Maintenance of Ballasted Tracks." Applied Sciences 12, no. 12 (June 11, 2022): 5973. http://dx.doi.org/10.3390/app12125973.

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Reverse engineering (RE) is a technology used to create three-dimensional (3D) models by scanning structures and can be used to examine the current condition of structures. Applying RE to the maintenance of railroad facilities with a high proportion of safety accidents can be an alternative to increase the efficiency of railroad facilities. However, most tasks while constructing Building Information Modeling (BIM) after 3D scanning and extracting two-dimensional (2D) drawings are still performed manually. In particular, denoising, registration, and 3D modeling based on point clouds are labor-intensive and time-consuming tasks, and their efficiency needs to be enhanced by introducing automation technology. In this study, we selected point clouds-based representative parameters for ballasted tracks of a straight single-line section for automating railroad maintenance. Scan data and a BIM of a ballasted track were compared using the selected representative parameters. In addition, the types of damage to ballasted track requiring maintenance were examined. And a testbed was consisted of ballasted a track was selected, and 3D scanning was performed to obtain point cloud data of a testbed. Then, a BIM model was created by measuring the numerical values corresponding to the representative parameters on the scan data. The feasibility of constructing a railroad maintenance BIM based on representative 3D object detection parameters during RE work on the ballasted track was evaluated.

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Martucci, Alessandra, Fabrizio Marinucci, Antonio Sivo, Alberta Aversa, Diego Manfredi, Federica Bondioli, Paolo Fino, and Mariangela Lombardi. "An Automatic on Top Analysis of Single Scan Tracks to Evaluate the Laser Powder Bed Fusion Building Parameters." Materials 14, no. 18 (September 9, 2021): 5171. http://dx.doi.org/10.3390/ma14185171.

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The production of dense samples produced by laser powder bed fusion (LPBF) is mainly determined by the choice of the best combination of construction parameters. Parameter optimization is the first step in the definition of an LPBF process for new alloys or systems. With this goal, much research uses the single scan track (SST) approach for a preliminary parameter screening. This study investigates the definition of a computer-aided method by using an automatic on top analysis for the characterization of SSTs, with the aim of finding ranges of laser power and scan speed values for massive production. An innovative algorithm was implemented to discard non-continuous scans and to measure the SSTs quality using three regularity indexes. Only open source software were used to fine tune this approach. The obtained results on Al4Cu and AlSi10Mg realized with two different commercial systems suggest that it is possible to use this method to easily narrow the process parameter window that allows the production of dense samples.

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Degenhardt, Brian F., Zane Starks, and Shalini Bhatia. "Reliability of the DIERS Formetric 4D Spine Shape Parameters in Adults without Postural Deformities." BioMed Research International 2020 (February 13, 2020): 1–10. http://dx.doi.org/10.1155/2020/1796247.

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The DIERS formetric 4D provides a safe method to monitor and track the progression of postural deformities over time. However, further evaluation of reliability is necessary. Reference values are also needed to indicate postural change. The current study examined the reliability of spine shape parameters produced by the formetric 4D in adults without postural abnormalities and established reference values to determine when real change occurs. Thirty participants were scanned during 1 week. Intraclass correlation coefficients (ICCs) were calculated for 40 spine shape parameters for scans with participants stationary between scans, scans with repositioning between scans, and between days. Within-day and between-day standard error of measurement (SEM), absolute relative SEM, and smallest detectable change (SDC) were reported. ICC for stationary scans was excellent for 29 parameters, good for 10 parameters, and fair for 1 parameter. With repositioning, ICC was excellent for 27 parameters, good for 12 parameters, and fair for 1 parameter. Between days, ICC was excellent for 26 parameters, good for 10 parameters, and fair for 4 parameters. Within-day SEM% was greater than 10% for 6 parameters. Within-day SDC ranged from 1.80 to 25.03 units for a single scan and from 0.97 to 17.93 units for 6 scans. Between-day SEM% was greater than 10% for 9 parameters. Between-day SDC ranged from 1.44 to 28.24 units for a single scan and from 1.05 to 22.2 units for 6 scans. Thirty-six of the 40 spine shape parameters from the DIERS formetric 4D reliably distinguished between participants over time. Reference values were established that can be used to track patient postural change over time. Future research should investigate the clinical relevance of these 40 spine shape parameters and determine when a clinically important change in posture occurs.

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Jhavar, S., C. P. Paul, and N. K. Jain. "Experimental investigation on geometrical aspects of micro-plasma deposited tool steel for repair applications." International Journal of Modern Physics: Conference Series 32 (January 2014): 1460347. http://dx.doi.org/10.1142/s2010194514603470.

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Recent advancement in direct material deposition processes found wide applications in rapid prototyping, manufacturing and tooling industry. Micro-plasma deposition is one of the recent developments in this domain. This paper reports the deployment of newly integrated micro-plasma deposition system for the deposition of AISI P-20 tool steel on the AISI P20 tool steel substrate. A number of test tracks for single track deposition were deposited at the various combination of processing parameters. The sets of parameters yielding good deposits were selected to deposit overlap tracks. The geometry of single and overlapped tracks was evaluated to understand the parametric dependence. The study indicates that the aspect ratio of track geometry (ratio of width to height of track) is dependent on the processing parameters and the discharge current is identified as the most dominating parameters (contribution = 44%), followed by scan speed (contribution = 26.68%) and wire feed rate (contribution = 26.98%) with almost same effect. The microscopic study of the deposits indicates that the material deposited at the optimum processing parameters is free from surface and bulk defects. The estimated material properties are found to be at par with conventional processed material. This feasibility study proved that the micro-plasma deposition can be used for the generation of surfaces and multi-featured material deposition. It paved a way for the application of the process in die/mold repairs.

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Більше джерел

Частини книг з теми "Single Scan Track"

Weaver, Jordan S., Meir Kreitman, Jarred C. Heigel, and M. Alkan Donmez. "Mechanical Property Characterization of Single Scan Laser Tracks of Nickel Superalloy 625 by Nanoindentation." In TMS 2019 148th Annual Meeting & Exhibition Supplemental Proceedings, 269–78. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-05861-6_24.

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Ravi, Prasanna, Romain Poussier, Shivam Bhasin, and Anupam Chattopadhyay. "On Configurable SCA Countermeasures Against Single Trace Attacks for the NTT." In Security, Privacy, and Applied Cryptography Engineering, 123–46. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-66626-2_7.

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Avanzini, Marco, Isabella Salvador, Elisabetta Starnini, Daniele Arobba, Rosanna Caramiello, Marco Romano, Paolo Citton, et al. "Following the Father Steps in the Bowels of the Earth: The Ichnological Record from the Bàsura Cave (Upper Palaeolithic, Italy)." In Reading Prehistoric Human Tracks, 251–76. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-60406-6_14.

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AbstractThe chapter summarizes the new results of the Bàsura Revisited Interdisciplinary Research Project. The integrated interpretation of recent archaeological data and palaeosurface laser scans, along with geoarchaeological, sedimentological, geochemical and archaeobotanical analyses, geometric morphometrics and digital photogrammetry, enabled us to reconstruct some activities that an Upper Palaeolithic human group led inside a deep cave in northern Italy within a single exploration event about 14 ka calBP. A complex and diverse track records of humans and other animals shed light on individual- and group-level behaviour, social relationship and mode of exploration of the uneven terrain. Five individuals, composed of two adults, an adolescent and two children, entered the cave barefoot lightening the way with a bunch of wooden sticks (Pinus t. sylvestris/mugo bundles). While proceeding, humans were forced to move on all fours, and the traces they left represent the first report of crawling locomotion in the global human ichnological record. Anatomical details recognizable in the crawling traces show that no clothing was present between limbs and the trampled sediments. Our study demonstrates that very young children (the youngest about 3 years old) were active members of the human groups, even in apparently dangerous and social activities, shedding light on behavioural habits of Upper Palaeolithic populations.

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M. Codêsso, José, Carlos A. Matos, and Clévio Nóbrega. "RNA Interference Applications for Machado-Joseph Disease." In RNA Therapeutics - History, Design, Manufacturing, and Applications [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.109261.

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Machado-Joseph disease (MJD), also named spinocerebellar ataxia type 3 (SCA3), is a dominantly inherited neurodegenerative disease caused by abnormal CAG expansions in MJD1 gene, which translate to an overexpanded tract of glutamines in the ataxin-3 (ATXN3) protein. Since the identification of the causative gene, a huge effort was made toward the development of animal models for MJD/SCA3, to increase the understanding of the molecular mechanisms underpinning disease pathogenesis, and to develop therapeutic strategies for the disease. Nevertheless, until now there are no therapies available capable of stopping or delaying the disease progression, which culminates with the death of the patients. Therefore, there is an urgent unmet need for therapeutic solutions, for which gene therapy stands out. The RNA interference (RNAi) mechanism discovery allowed the identification of small RNA molecules with the ability to regulate gene expression. For gene therapy, RNAi provided a way to silence mutant genes, which are particularly useful in dominantly inherited diseases. In the last years, several studies have focused on using RNAi molecules to target mutant ATXN3. The results showed that this could be an efficient and safe strategy for modifying MJD/SCA3 progression. Now, an additional effort must be done to translate these results into clinical trials.

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Chen, Xingyu, John Yu, Pamela Goh, Loo Seng Neo, Verity Er, and Majeed Khader. "Crime-Fake News Nexus." In Encyclopedia of Criminal Activities and the Deep Web, 52–65. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-5225-9715-5.ch004.

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Fake news has been a popular topic since the 2016 U.S. elections, where researchers have studied its impact on politics and social unrest. In recent times, there have been cases of fake news being perpetrated for criminal gain. For example, in Singapore, names of high-profile figures were used by scammers to trick people to invest in dubious cryptocurrency. Such cases highlight the emergence of a nexus between fake news and crime, for which there is scant literature. To enhance current understanding about this growing concern, this chapter examines 32 crime-fake news incidents in Singapore from 2013 to 2018. Based on a descriptive analysis of these cases, this chapter aims to answer the following questions: (1) What are the types of crime-fake news in Singapore? (2) What is the impact that it has in Singapore? (3) Who are these fake news creators and what motivates them? (4) What are the popular methods of transmitting crime-fake news? and (5) Who responds to the crime-fake news? In addition, implications in the areas of public education and crime prevention will be discussed.

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Yenidünya Konuk, Elçin. "Molecular Approaches to the Diagnosis of Chlamydia." In Infectious Diseases. IntechOpen, 2023. http://dx.doi.org/10.5772/intechopen.109746.

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Chlamydia trachomatis is known as the most common bacterial infection agent to pass with sexual transition. This microorganism is an obligatory intracellular parasite. A variety of infections are caused by C. trachomatis, including trachoma, pneumonias in newborns, genital and urinary tract infections, and lymphogranuloma venereum (LGV), which is caused by LGV strains. The diagnosis of Chlamydia trachomatis can be made by cultures and isolations, antigens and antibodies (direct fluorescence, enzyme immunoassays), hybridization, or polymerase chain reaction (PCR). Each year, infection and diagnosis rates increase in the developed world. Since Chlamydia is mostly asymptomatic, screening, and treatment are a key to detecting cases. Polymerase chain reaction (PCR), ligase chain reaction (LCR), and nucleic acid sequence-based amplification (NASBAa) molecular methods can be used for the detection, low concentration, quantification, and identification of organisms. While the traditional PCR method confirms its existence, it can quantify real-time PCR (RT-PCR). This method (RT-PCR) may have low sensitivity among variants of the same species. Also, PCR scans, which receive urine service, offer great advantages. PCR from initial void urine (FVU) samples is highly sensitive in detecting the organism. Urine Chlamydia screenings are more acceptable in large populations and asymptomatic detections.

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Тези доповідей конференцій з теми "Single Scan Track"

Rauniyar, Santosh, and Kevin Chou. "Transient Melt Pool Formation in Laser-Powder Bed Fusion Process." In ASME 2020 15th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/msec2020-8345.

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Abstract Parts are built in a layer-by-layer fashion in the laser powder bed fusion process. Each layer of scan in the parts is defined by a scan strategy that consists of many small patches and scans. The scan length of those multiple scans is not always long enough to have reached a quasi-steady state of the melt pool. The length at which it achieves a steady state is different for different process parameters. The available literature related to the melt pool considers the melt pool has already achieved a steady state, which holds true to a large extent. However, there is always a transient state of melt pool with different characteristics compared to the quasi-steady state. The transient state of the melt pool is particularly significant for small features and thin walls. This paper explores the cross-section and width of the melt track in the transient state. Single-tracks are deposited on semi-cylindrical samples with Ti-6Al-4V powder particles for three levels of power and speed combinations. The single tracks are built at a certain height from the base plate instead of on the build plate to include the effect of the powder particles. The experiment includes single tracks of four scan lengths i.e. 0.25, 0.5, 1 and 2 mm. Once the parts are built and removed from the build plate, White light interferometer is used to capture the melt track information and data processing is done in Matlab™. The results show that the transient length is directly proportional to the laser power and inversely proportional to the scan speed. The highest transient length value is obtained for the highest power of 195 W and lowest scan speed of 50 mm/s.

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Heigel, J. C., and B. M. Lane. "Measurement of the Melt Pool Length During Single Scan Tracks in a Commercial Laser Powder Bed Fusion Process." In ASME 2017 12th International Manufacturing Science and Engineering Conference collocated with the JSME/ASME 2017 6th International Conference on Materials and Processing. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/msec2017-2942.

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This work presents high speed thermographic measurements of the melt pool length during single track laser scans on nickel alloy 625 substrates. Scans are made using a commercial laser powder bed fusion machine while measurements of the radiation from the surface are made using a high speed (1800 frames per second) infrared camera. The melt pool length measurement is based on the detection of the liquidus-solidus transition that is evident in the temperature profile. Seven different combinations of programmed laser power (49 W to 195 W) and scan speed (200 mm/s to 800 mm/s) are investigated and numerous replications using a variety of scan lengths (4 mm to 12 mm) are performed. Results show that the melt pool length reaches steady state within 2 mm of the start of each scan. Melt pool length increases with laser power, but its relationship with scan speed is less obvious because there is no significant difference between cases performed at the highest laser power of 195 W. Although keyholing appears to affect the anticipated trends in melt pool length, further research is required.

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Pappas, John M., and Xiangyang Dong. "Effects of Processing Conditions on Laser Direct Deposited Alumina Ceramics." In ASME 2020 15th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/msec2020-8260.

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Abstract Additive manufacturing (AM) of high-quality inherently brittle ceramics via laser direct deposition, also known as laser engineered net shaping, is challenging due to high thermal gradients, thermally induced cracks, and porosity, typically accompanied by low powder usage efficiency. It is necessary to have an improved understanding of the effects of processing conditions on the fabricated ceramic parts. In this study, alumina ceramics were fabricated with commercial alumina powders. In particular, this paper studied the effect of laser power and scan speed on single track geometries, thin-wall morphology, grain size, density, and powder efficiency during laser direct deposition of alumina ceramics. A single-track parametric study was first conducted to determine the range of processing parameters that produce quality single-tracks and to aid in matching the z-increment with layer thicknesses. The results showed that increased scan speeds promoted significant grain refinement. Average grain size was reduced by nearly 50% when scan speed was increased from 1000 mm/min to 5000 mm/min. On the other hand, densification reached a maximum of 98% at a scan speed of 1000 mm/min with a slight decrease in density was observed at higher speeds. This indicated a trade-off between porosity and grain size when altering the laser scan speed. Significant advantages of using CO2 lasers for AM of ceramics was also demonstrated with powder usage efficiencies reaching nearly 90% under optimized processing conditions.

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Kyogoku, Hideki, Takeshi Uemori, Akihiko Ikuta, Kenichi Yoshikawa, and Hitoshi Ohmori. "Direct Selective Laser Sintering of WC-Co Cemented Carbide by Premixing of Additives." In ASME/ISCIE 2012 International Symposium on Flexible Automation. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/isfa2012-7182.

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In this study, the fabrication conditions of WC cemented carbides by direct selective laser melting were investigated. The effects of additives, such as Co, Cu-20%Sn and Cu powders, and laser scanning conditions on laser sintering process were examined to fabricate a sound laser-scanned body of WC cemented carbides. The optimum laser power, scan speed and scan pitch were found out by experiments. It was found that the continuously smooth single-scan track can be obtained at a lower laser power and a higher scan speed by the addition of 30% Cu powder. The smooth surface of the laser-scanned body could be fabricated at a laser power of 9 W, a scan speed of 20 mm/s and a scan pitch of 0.05 mm.

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Zhang, Shanshan, Sabina Chertmanova, and Kevin Chou. "Surrogate Pore Generations in L-PBF Ti64 and Effects on Mechanical Behavior." In ASME 2020 15th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/msec2020-8470.

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Abstract In this study, surrogate pores were designed and generated at specific locations inside tensile specimens fabricated by laser powder bed fusion (L-PBF) processing and further evaluated in porosity characteristics and mechanical properties. The objectives are to demonstrate the feasibility of pore generation and to characterize the pores and examine the effect from various process conditions. The pore-generated specimens were fabricated in an L-PBF system using Ti-6Al-4V (Ti64) powder. Overall, specimens were made using default settings. But, during processing the middle section of the tensile specimens, single track exposures were applied to induce keyhole pores with different energy density levels as well as different scan track numbers and layers. An X-ray computed tomography system was utilized to measure and analyze surrogate pores in the fabricated specimens in pore counts, volumes and sphericity related to process conditions. The results showed that, as expected, pore formation increases with the laser energy density applied and the number of tracks and layers exposed, although individual tracks exhibit a high variability. Specimens evaluated by tensile testing and fractography show that surrogate pores produced in this study so far influence only the ductility of the specimens noticeably, but not Young’s modulus, nor the yield and tensile strengths.

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Sammons, Patrick M., Douglas A. Bristow, and Robert G. Landers. "Height Dependent Laser Metal Deposition Process Modeling." In ASME/ISCIE 2012 International Symposium on Flexible Automation. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/isfa2012-7238.

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Laser Metal Deposition (LMD) is used to construct parts in a layer-by-layer fashion. The heat transfer from the melt region to the solid region plays a critical role in the resulting material properties and part geometry. The heat transfer dynamics can change significantly as the layers increase, depending on the geometry of the sub layers. However, this effect is unaccounted for in previous analytical models, which model only a single layer. This paper develops a layer dependent model of the LMD process for the purpose of designing advanced layer-to-layer controllers. A lumped-parameter model of the melt pool is introduced and then extended to include elements that capture height dependent effects on the melt pool shape. The model dynamically relates the process inputs (e.g., laser power, material mass flow rate, and scan speed) to the melt pool morphology and temperature. A finite element analysis is then conducted to determine the effect of scan speed and track height on the solid region temperature gradient at the melt pool solidification boundary. The results of a simulation study are compared to experimental results in the literature and demonstrate that the model is able to successfully predict changes in melt pool width as track height increases, which single layer models cannot.

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Schmidt, M., S. Gorny, N. Rüssmeier, and K. Partes. "Investigation on Laser Cladding Processes Using High-Resolution In-Line Atomic Emission Spectroscopy." In ITSC2022. DVS Media GmbH, 2022. http://dx.doi.org/10.31399/asm.cp.itsc2022p0876.

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Abstract Process monitoring and control methods during direct metal deposition (DMD) are used to ensure a consistent manufacturing quality of the process. In the optical regime, naturally occurring process emission provides therefore selective and specific element lines, which can be obtained by optical spectrometers. However, DMD processes are in the heat conduction regime and superimposed broad spectral emissions dominate the wavelength specific signals. The aim of this work is to investigate the occurrence of different elemental lines in DMD processes as well as deposition track cross-sectional dimensions. Therefore, experiments were simultaneously conducted by using a high-resolution spectrometer (resolution = approx. 47 pm FWHM at 522 nm and 55 pm FWHM at 407.5 nm) and a medium resolution spectrometer (resolution = 0.73 nm FWHM), which were coupled by a bifurcated optical fibre. A parameter study of 27 single track DMD experiments using Co-Cr-based (MetcoClad21) powder on low-alloyed tool steel C45W (1.1730) substrate material, varying laser power, scan velocity and powder feed rate was conducted. Series of spectra were obtained for all sets of parameters with a scan rate of 100 Hz. The individual wavelength spectrum was analysed and classified by an algorithm into two types. Type-A spectra, with specific element emission lines and Type-B spectra, without significant emission lines with mostly predominant thermal emission radiation. Each deposition track was coupled to cross-sectional dimensions, including height, welding depth and melted areas. In addition, certain elemental lines contained in Type-A spectra were verified by using data from the NIST atomic spectra database. The investigation indicates that the relative number of Type-A spectra with respect to the total quantity of spectra, correlates significant to the process parameters. All detected and identified element lines occurred to be non-ionised elements, especially Cr I, Fe I and Mn I lines were frequently observed.

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Fan, Rong, Michael S. Sacks, Ahmed Bayoumi, John E. Mayer, Christopher M. Hobson, and William R. Wagner. "Optimization of Engineered Ovine Pulmonary Heart Valve Leaflet Tissue Shape for Single Leaflet Replacement." In ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80824.

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Pulmonary valve (PV) replacement surgery is a treatment option for patients with a congenitally defective pulmonary outflow track. While a tissue engineered approach offers many potential advantages, develop of such a valve involves a complex process of optimization. As an intermediate step, we have used a single leaflet replacement surgical model to further our understanding of the in-vivo remodeling process. A critical step is to determine the deformed shape of the replacement PV leaflet under transvalvular pressure. Key factors in this process are: the scaffold anisotropic mechanical properties, optimal thickness, and the exact initial leaflet shape. We have used electrospun poly (ester urethane) ureas (ES-PEUU) scaffolds since they exhibit mechanical properties very similar to the native PV. In this work we present a design framework of the optimal leaflet shape determination utilizing a single sheet of ES-PEUU for single leaflet replacement surgery via finite element (FE) simulation. The mechanical properties of ES-PEUU scaffold for leaflet replacement were obtained from biaxial in-plane tension experiments. Generalized Fung-type hyperelastic constitutive model [1] was implemented into a commercial FE software package to simulate the deformation of ES-PEUU scaffolds under pressure. By perturbing the initial shape of leaflet and simulating its quasi-static deformation under PV diastolic loading, the optimal shape of unloaded leaflet was determined by comparing the deformed shape of leaflet obtained from FE simulation of TEPV with the one from microCT scan of a native ovine PV. In-vitro test of PV after single leaflet replacement was also conducted to validate the developed method.

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Fan, Rong, Christopher M. Hobson, Ahmed Bayoumi, John E. Mayer, William R. Wagner, and Michael S. Sacks. "Design of Tissue-Engineered Leaflet Shape for the Ovine Pulmonary Valve Single Leaflet Replacement Surgery." In ASME 2011 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2011. http://dx.doi.org/10.1115/sbc2011-53949.

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Pulmonary valve (PV) replacement surgery is a treatment option for patients with a congenitally defective pulmonary outflow track. A tissue engineered pulmonary valve (TEPV) is a potential approach to serve as a replacement pediatric heart valve that has the potential for somatic growth. The single leaflet replacement surgical model can assist in assessing candidate biomaterials responses to in-vivo function. However, an empirically determined unloaded leaflet shape may result in abnormal valve function due to incomplete coaptation of leaflets and asymmetric stress distributions. Thus, to determine the final deformed shape of an engineered scaffold replacement PV leaflet under transvalvular pressure the following key factors must be determined: the scaffold anisotropic mechanical properties, optimal thickness, and the exact initial leaflet shape. We have used electrospun poly (ester urethane) ureas (ES-PEUU) scaffolds since they exhibit mechanical properties very similar to the native PV [1]. In this work we present a design framework of the optimal leaflet shape determination utilizing a single sheet of ES-PEUU for single leaflet replacement surgery via finite element (FE) simulation. The mechanical properties of ES-PEUU scaffold for leaflet replacement were obtained from biaxial in-plane tension and three-point bending flexural deformation experiments. Generalized Fung-type hyperelastic constitutive model [2] was implemented into a commercial FE software package to simulate the mechanical behavior of ES-PEUU scaffolds. By perturbing the initial shape of leaflet and simulating its quasi-static deformation under PV diastolic loading, the optimal shape of unloaded leaflet can be determined by comparing the deformed shape of leaflet obtained from FE simulation of TEPV with the one from microCT scan of a native ovine PV.

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Chang, Yuhe, and Sean B. Andersson. "Observer-Based Control of a Dual-Stage Piezoelectric Scanner." In ASME 2019 Dynamic Systems and Control Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/dscc2019-9163.

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Abstract Despite its proven success in a wide variety of applications, the atomic force microscope (AFM) remains limited by its slow imaging rate. One approach to overcome this challenge is to rely on algorithmic approaches that reduce the imaging time not by scanning faster but by scanning less. Such schemes are particularly useful on older instruments as they can provide significant gains despite the existing (slow) hardware. At the same time, algorithms for sub-sampling can yield even greater improvements in imaging rate when combined with advanced scanners that can be retrofitted into the system. In this work, we focus on the use of a dual-stage piezoelectric scanner coupled with a particular scanning algorithm known as Local Circular Scan (LCS). LCS drives the tip of the AFM along a circular trajectory while using feedback to center that circle on a sample edge and to move the circle along the feature, thus reducing imaging time by concentrating the samples to the region of interest. Dual-stage systems are well-suited to LCS as the algorithm is naturally described in terms of a high-frequency, short range path (the scanning circle) and a slower, long range path (the track along the sample). However, control of the scanner is not straightforward as the system is multi-input, single-output. Here we establish controllability and observability of the scanning stage, allowing us to develop individual controllers for the long-range and short-range actuators through the principle of separation. We then use an internal model controller for the short range actuator to track a sinusoidal input (to generate the circular motion) and a state-space set-point tracking controller for the long range actuator. The results are demonstrated through simulation.

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